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WIRELESS SENSOR NETWORKS
1
CHAPTER 1: INTRODUCTION
1>MEMS stands for__________
2>A sensor network is subject to a unique set of resource constraints such as
a: finite on-board battery power
b: limited network communication bandwidth
Ans: ________ (a/b/both)
3>In a typical sensor network, each sensor node operates unethered and has a microprocessor and
a small amount of memory for signal processing and task scheduling (true/false)__________
4>Each node is equipped with one or more sensing devices such as acoustic microphone arrays,
video or still cameras, infrared, seismic or magnetic sensors (true/false)__________
5>Information collected by and transmitted on a sensor network describes conditions of physical
environments and requires advanced query interfaces and search engines to effectively support
user-level functions (true/false)__________
6>___________routes user queries or commands to appropriate nodes in a sensor network
(bridge/gateway)
7>Communicating 1 bit over the wireless medium at short ranges consumes ___________energy
than processing that bit (less/more)
8>For the Sensoria sensors and Berkeley motes, the ratio of energy consumption for communication
and computation is in the range of _____to______ (100/1000/10000)
9>A sensor network is designed to collect information from a___________ environment
(logical/physical)
10>Table1.1___________
11>It is more appropriate to address nodes in a sensor network by_____ than by______ (IP
address/physical properties)
12>Mobility and instability in wireless links prevent the use of many existing edge network gateway
protocols for internetworking IP and sensor networks (true/false)__________
13>The challenges we face in designing sensor network systems and applications include
a: limited hardware
b: limited support for networking
c: limited support for software development
Ans: ___________ (a/b/c/all)
14>Match the following
Limited hardware: the tasks are typically real-time and massively distributed,
involve dynamic collaboration among nodes, and must handle
multiple competing events
Limited support for
networking:
each node has limited processing, storage and communication
capabilities, and limited energy supply and bandwidth
Limited support for
software
development:
the network is peer-to-peer , with a mesh topology and
dynamic, mobile and unreliable connectivity
15>Following are advantages of sensor network
a: energy advantage
b: detection advantage
Ans: ___________ (a/b/both)
16>Dense networks of distributed communicating sensors can improve SNR by reducing average
distances from sensor to source of signal or target (true/false)__________
17>The greatest advantage of networked sensing are in improved___________
(robustness/scalability/both)
18>A___________ sensing system is inherently more robust against individual sensor node or link
failures, because of redundancy in the network (centralized/decentralized)
19>Because of the unique attenuation characteristics of RF signals, _____network provides a
significant energy saving over ______network for the same distance (single hop/multi hop)
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20>The RF attenuation model near the ground is given by
a: Preceive ¤ Psend/r
b: Psend ¤ Preceive/p
Ans: ___________ (a/b/either)
21>In above expression, alpha is typically in the range of__to___ (2/3/4/5)
22>The power advantage of an N-hop transmission versus a single hop transmission over the same
distance Nr is
a: nrf=N(alpha-1)
b: nrf=N(alpha+1)
Ans: ___________ (a/b/both)
23>In above expression, ___________N gives a larger power saving due to the consideration of RF
energy alone (smaller/larger)
24>Using more nodes increases
a: the cost
b: the power consumption of components
Ans: ___________ (a/b/both)
25>Each sensor has a finite sensing range, determined by the___________ floor of the sensor
(ground/noise)
26>Densor sensor field improves the odds of detecting a signal source within the range
(true/false)___________
27>Once a signal source is inside the sensing range of a sensor, further increasing the sensor
density ___________the average distance from a sensor to the signal source, hence improving the
SNR (decreases/increases)
28>wrt the acoustic sensing case in a two-dimensional plane, the acoustic power received at a
distance r is given by
a: Psend ¤ Precieve/r*r
b: Preceive ¤ Psource/r*r
Ans: ___________ (a/b/either)
29>Wrt acoustic sensing case in a two-dimensional plane, the SNR is given by
a: SNR=10logPsource+10logPnoise+20logr
b: SNR=10logPsource-10logPnoise-20logr
Ans: ___________ (a/b/either)
30>The SNR advantage of the denser sensor network is given by
a: nsnr=20logk
b: nsnr=10logk
Ans: ___________ (a/b/either)
31>An increase in sensor density by a factor of k improves the SNR at a sensor by ___________db
(10logk/20logk)
32>A sensor network is designed to perform a set of high level information processing tasks such as
a: detection
b: tracking
c: classification
Ans: ___________ (a/b/c/all)
33>Following are sample commercial and military applications include
a: environmental monitoring
b: industrial sensing and diagnostics
c: infrastructure protection
d: battlefield awareness
e: context aware computing
Ans: ___________ (a/b/c/d/e/all)
34>Match the following
environmental monitoring : intelligent home, responsive environment
Industrial sensing and diagnostics : multi-target tracking
Infrastructure protection : power grids, water distribution
Battlefield awareness : traffic, habitat, security
Context aware computing : appliances, factory, supply chains
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35>If every sensor has some data that it needs to send to another node in a network, then per node
throughput scales as___________{sqrt(N) or 1/sqrt (N)}
36>As the number of nodes___________, every node spends almost all of its time forwarding
packets of other nodes (decreases/increases)
37>CSIP stands for___________
38>___________refers to signal and information processing problems dominated by the issue of
selecting embedded sensors to participate in an information processing task (CSIP/CCIP)
39>___________is an interdisciplinary research area that draws on contributions from signal
processing, networking and protocols, databases and information management, distributed
algorithms, and embedded systems and architecture (wireless networks/sensor networks)
40>Match the following
sensor: routing of data based on geographical attributes such as locations
or regions
sensor node: the process of determining a network path from a packet source
node to its destination
network
topology:
approaches that name, route or access a piece of data via
properties that are external to a communication network
routing: a transducer that converts a physical phenomenon that may be
further manipulated by other apparatus
data centric: a basic unit with on-board sensors, processor, memory, wireless
modem and power supply
geographic
routing:
a connectivity graph where nodes are sensor nodes and edges are
communication links
41>Match the following
In-network: the process of discovering the existence of a physical
phenomenon
Collaborative
processing:
either high-level system tasks which may include sensing,
communication, processing and resource allocation or application
tasks which may include detection, classification , localization or
tracking
State: a condition of the information caused by noise in sensor
measurements or lack of knowledge in models
Uncertainty: a snapshot about a physical environment or a snapshot of the
system itself
Task: sensors cooperatively processing data from multiple sources in
order to serve a high level task
Detection: a style of processing in which the data is processed and combined
near where the data is generated
42>Match the following
Classification: the assignment of sensors to a particular task and the control of
sensor state for accomplishing the task
Localization &
tracking:
services such as time synchronization and node localization that
enable applications to discover properties of a node and the nodes
to organize themselves into a useful network
Value of
information:
resources include sensors, communication links, processors , on-
board memory and node energy reserves
Sensor tasking: the estimation of the state of a physical entity such asa physical
phenomenon or a sensor node from a set of measurements
Resource: a mapping of data to a scalar number, in the context of the
overall system task and knowledge
Node services: the assignment of class labels to a set of physical phenomena
being observed
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43>Match the following
Data storage: the abstract characterization of system properties
Embedded OS: a measurable quantity that describes how well the system is
performing on some absolute scale
System
performance
goal:
sensor information is stored, indexed and accessed by
applications
Evaluation
metric:
the run-time system support for sensor network applications
ANSWERS
1>Micro Electro Mechanical System
2>both
3>T
4>T
5>T
6>gateway
7>more
8>1000 to 100000
9>physical
10>
11>physical properties, IP address
12>T
13>all
14>1-b 2-c 3-a
15>both.
16>T
17>Both
18>decentralised
19>multihop, single hop
20>a
21>2-5
22>a
23>larger
24>both
25>noise
26>T
27>decreases
28>b
29>b
30>b
31>10logk
32>all
33>all
34>1-d 2-e 3-c 4-b 5-a
35>1/sqrt(N)
36>increases
37>Collaborative Signal & Information Processing
38>CSIP
39>sensor networks
40>1-d 2-e 3-f 4-b 5-a 6-c
41>1-f 2-e 3-d 4-c 5-b 6-a
42>1-f 2-d 3-e 4-a 5-c 6-b
43>1-c 2-d 3-a 4-b
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CHAPTER 2: CANONICAL PROBLEM –
LOCALIZATION AND TRACKING
1>Localizing and tracking moving objects is an essential capability for a sensor network in many
practical applications (true/false)__________
2>A central problem for CSIP is to dynamically define and form sensor groups based on__________
(task requirements/resource availability/both)
3>A sensor network can be defined as an abstract tuple G=<V, E, Pv, Pe> where
__specifies nodes, ___specifies link connectivity, __is a set of functions that characterizes the
properties of each node and ___specifies properties of each link
4>DOA stands for__________
5>__________is a distributed physical quantity such as temperature, pressure or optical flow across
a region of space (area/field)
6>A tracking task can be formulated as a constrained optimization problem <G, T, W, Q, J, C>
where__is the sensor network , __is a set of targets, __is a signal model for how target signals
propagate and attenuate in the physical medium, __denotes a set of user queries, __specifies an
objective function defined by task requirements and__ specifies a set of constraints
7>In wireless sensor networks, some of the information defining the objective function and
constraints is available only at___________ (compile time/run time)
8>The position estimation may be accomplished by
a: triangulation computation
b: least square computation
Ans: ___________ (a/b/either)
9>Bayesian estimation can be used for position estimation (true/false)___________
10>When the two targets move close to a target track, ___________problem has to be addressed
(data relationship/data association)
11>Tracking scenario raises following fundamental information processing issues
a: in collaborative processing, the issue of target detection, localization, tracking and sensor tasking
and control
b: in networking, the issues of data naming , aggregation and routing
c: in databases, the issues of data abstraction and query optimization
d: in human-computer interface, the issues of data browsing , search and visualization
e: in infrastructure services, the issues of network initialization and discovery, time ad location
services, fault management and security
Ans: ___________ (a/b/c/d/e/all)
12>Give an expression relating zi, ai, x, wi , and Ans: __________
13>To uniquely determine the location on a two-dimensional plane, one needs alleast
___________independent distance measurements (two/three)
14>TDOA stands for___________
15>___________determines the significance of the contribution of each sensor
a: geometry of the sensor placement
b: distance to the signal source
Ans: __ (a/b)
16>The goal of localization or tracking is to obtain a good estimate of the target state from the
measurement history (true/false)__________
17>We refer to the___________ distribution as the current belief (priori/posterior)
18>The relationship between the posterior distribution p (x|z), the priori distribution p (x) , and the
likelihood function p (z|x) is given by Bayes Theorem
a: p (x|z)=p (z|x)p (x)/p (x)
b: p (x|z)=p (z|x)p (x)/p (z)
Ans: ___________ (a/b/either)
19>In above expression, ____is the marginal distribution, which is also called the normalizig
constant{p (x) or p (z)}_______
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20>MMSE stands for___________
21>A commonly used estimator in the standard estimation theory is the___________
(MEMS/MMSE)
22>The___________ algorithm is inefficient in utilizing the communication resources
(centralized/distributed)
23>From the processing point of view, the complexity of the___________ algorithm scales linearly
with K, and hence is prohibitive for large networks (centralized/distributed)
24>In___________ filter, the belief distributions and error models are Gaussians and the system
dynamics model is linear (kalman/particle)
25>In following ways we can approximate an arbitrary belief state regarding the targets
a: we can approximate the belief by a family of distributions
b: we can approximate the belief by weighted point samples
Ans: ___________ (a/b/both)
26>PMF stands for___________
27>We can approximate the belief by weighted point samples .Following are examples of this
approximation
a: discretizing the subset of S by a grid
b: the particle filter approximation of distribution
c: the kalman filter approximation of distribution
Ans: __________ (a/b/c/all)
28>A variant of belief approximation by weighted point samples is to partition S and assign a
probability value to each region which is called ___________type approach (histogram/heuristic)
29>The belief approximation by weighted point samples is called__________
(parametric/nonparametric)
30>The belief approximation by a family of distribution is called___________
(parametric/nonparametric)
31>If we must pass the belief to a remote sensor, we are faced with the following trade off.
Representing the true belief by a______ approximation with relatively few parameters will result in a
poor approximation of the belief state but with the benefit that fewer bits need to be transmitted. On
the other hand, representing the true belief by_____ approximation will result in a more accurate
approximation of the belief at the cost of more transmitted bits (parametric/nonparametric)
32>Gaussian approximation is example of___________ approximation (parametric/nonparametric)
33>In the___________ design, the robustness of the tracker may suffer from occasional leader
node attrition (moving leader/single moving)
34>The___________ design can be used for tracking multiple targets in a sensor field, with one
leader-node tracking each target (moving leader/single moving)
35>The belief state can be stored in a distributed fashion across a section of sensor nodes. This is
attractive from the___________ point of view (robustness/security)
36>___________is key problem in designing distributed CSIP applications (information
representation/storage/ access/all)
37>While defining a unifying architecture for sensor networks is still an open problem, a key
element of such an architecture is the principled interaction between the______ &_____layers
(application/transport/network)
38>Tracking multiple interacting targets distributed over a geographical region is significantly more
challenging for following reasons
a: curse of dimensionality
b: mapping to distributed platforms
Ans: ___________ (a/b/both)
39>The presence and interaction of multiple phenomena cause the dimension of the underlying
state spaces to ___________ (decrease/increase)
40>To ensure the ___________of the system, the communication and computation should be
localized to relevant sensors only (responsiveness/scalability/both)
41>The key idea in the state-space factorization is to decouple information in a state space
into___________ information (location/identity/both)
42>The tracking problem can be solved separately by______ which requires frequent local
communication, and by_____ which requires less frequent, longer range communication (location
estimation/identity management)
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43>Following approaches can be used for tracking multiple objects
a: state space decomposition
b: data association
Ans: ___________ (a/b/both)
44>In___________ approach, the target location and identity information are coupled and
processed in the same space (state space decomposition/ data association)
45>To address the data association problem, following methods can be used________
(MHT/JPDA/both)
46>MHT stands for___________
47>JPDA stands for___________
48>_____forms and maintains multiple association hypotheses. On the other hand,
______evaluates the association probabilities and combines them to compute the state estimate
(MHT/JPDA)
49>The distributed ___________filter is a global method, requiring each sensor node to
communicate its measurement to a central node, where estimation and tracking are carried out
(kalman/particle)
50>In___________ filter method, sensing is distributed while tracking is centralized
(kalman/particle)
51>Replicated information is one of the serious problem in distributed tracking, whether the tracking
is about a single target or multiple targets (true/false)___________
52>Following are sources of information double counting
a: due to loopy propagation of evidence in a network
b: due to multiple sensor nodes observing a single target and reporting multiple detections
Ans: ___________ (a/b/both)
53>Following are common types of sensors for tracking
a: acoustic amplitude sensors
b: DOA sensors
Ans: ___________ (a/b/both)
54>DOA stands for___________
55>___________sensor node measures sound amplitude at the microphone and estimates the
distance to the target based on the physics of sound attenuation (acoustic DOA/acoustic amplitude)
56>___________sensor is a small microphone array. Using beam forming techniques, it can
determine the direction from which the sound comes, that is, the bearing of the target (acoustic
DOA/acoustic amplitude)
57>______sensors estimate distance based on received signal strength or TOA, while_____ sensors
estimate signal bearing based on TDOA (range/DOA)
58>for sensor network applications, a sensor may be characterized by properties such as cost, size,
sensitivity, resolution, response time, energy usage and ease of calibration & installation
(true/false)___________
59>RMS stands for___________
60>Assuming that the sound source is a point source and sound propagation is lossless and
isotropic, RMS amplitude measurement z is related to the sound position x by
Ans: ___________
61>___________sensing provides a range estimate (frequency/amplitude)
62>___________algorithms are commonly used in radar, speech processing and wireless
communication to enhance signals received at an array of sensors (beam forming/bayesian state)
63>The relative time delay between two sensors with a spacing d can be expressed as a function of
the bearing angle given by
a: tm= (d/c)sin
b: tm= (c/d)sin
Ans: ___________
64>Following methods are examples of DOA estimation algorithms___________ (least
squares/maximum likelihood/both)
65>___________method solves for target bearing and location by estimating first the time
difference of arrival at a set of sensors and then the source location (least squares/maximum
likelihood)
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66>___________method typically converts a set of signals from time domain to frequency domain
and then performs a possibly multidimensional search to find the peak in the correlation spectra
(least squares/maximum likelihood)
67>_____method can be applied to both near and far field problems whereas______ method is
particularly useful for near field problems in which the target is relatively close to the sensors
compared with the sensor spacing (least squares/maximum likelihood)
68>In DOA sensor, The likelihood function is given by
Ans: ___________
69>The DOA estimate is_____ reliable in the medium distance range and is______ reliable when
the sound source is too close or far away from the microphone array (less/more)
70>wrt DOA sensor, in the_____ field, the planar wave assumption is violated. In the______ field,
the SNR is low, and he DOA estimation may be strongly influenced by noise and fail to converge to
the correct angle (near/far)
71>Following are some of the commonly used measures of performance
a: delectability
b: accuracy
c: scalability
d: survivability
e: resource usage
Ans: ___________ (a/b/c/d/e/all)
72>Match the following
Delectability: what is the amount of resources that each task consumes
Accuracy: how does the system perform in the presence of node or link
failures as well as malicious attacks
Scalability: this may be measured by sensor coverage, detection resolution,
dynamic range or response latency
Survivability: this is typically characterized in terms of tracking errors or detection
and classification errors
Resource
usage:
how does a specific property of the system vary as the size of the
network, the number of physical stimuli or the number of active
queries increases
73>For___________ problems, performance is typically measured by false alarms and misses
(detection/classification/tracking/all)
74>For___________ problem, performance goals and measures can be stated in terms of target
and system parameters (detection/classification/tracking/all)
75>_____occurs when the outcome is incorrectly predicted as a positive when it is in fact a
negative.______ is when the outcome is incorrectly labeled as a negative when in fact it is a positive
(false negative/false positive)
76>Match the following
Source SNR : percentage of runs of a full scenario where continuity
of vehicle identity is
not correctly maintained
Obstacle density : the number of hours of target tracking versus the total
number of node hours
in fully awake mode for the entire network
Network sleep efficiency : this may be measured by the probability of LOS
obstruction for a randomly
placed target-sensor pair
Percentage of track loss : this is measured as the SNR at a reference distance
from the signal source
___________
77>For an acoustic source, ___________is defined as the log ratio of SPL of source at the reference
distance over SPL of background noise (source SNR/receiver SNR)
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78>Match the following
Detection of robustness : active lifetime, sleep lifetime, sleep efficiency
Detection spatial resolution : link capacity
Detection latency : %node loss
Classification robustness : sensor coverage area, target maneuvers, obstacle
density
Track continuity : source SNR
System survivability : link delay
Cross-node DOA estimation : inter-target spacing
Power efficiency :
ANSWERS
1>T
2>both
3>V,E,Pv,Pe
4>Direction-Of-Arrival
5>field
6>G, T, W, Q, J, C
7>run time
8>both
9>T
10>data association
11>all
12>z = h(x , )
13>3
14>Time Difference Of Arrival
15>both
16>T
17>posterior
18>b
19>p(z)
20>Minimum Mean Squared Error
21>MMSE
22>centralized
23>centralized
24>Kalman
25>both
26>Probability Mass Function
27>a, b
28>histogram
29>non parametric
30>parametric
31>parametric, non-parametric
32>parametric
33>single moving
34>moving leader
35>robustness
36>all
37>application, networking
38>both
39>increase
40>both
41>both
42>location estimation, identity management
43>both
44>data association
45>both
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46>Multiple Hypothesis Tracking
47>Joint Probabistic Data Association
48>MHT,JPDA
49>Kalman
50>kalman
51>T
52>both
53>both
54>Direction of arrival
55>acoustic amplitude
56>acoustic DOA
57>range, DOA
58>T
59>Root Mean Square
60>z=a/x- + w
61>amplitude
62>beam forming
63>a
64>both
65>least square
66>ML(maximum likelihood)
67>ML
68>
69>more, less
70>near, far
71>all
72>1-c 2-d 3-c 4-b 5-a
73>dtection, classification
74>tracking
75>false positive, false negative
76>1-d 2-c 3-b 4-a
77>source SNR
78>1-e 2-g 3-b 4-e 5-d 6-c 7-b 8-a
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CHAPTER 3: NETWORKING SENSORS
1>Networking allows geographical distribution of the sensor nodes and their placement close to
signal sources (true/false)__________
2>Radio communication is the most expensive operation a node performs in terms of energy usage,
and thus it must be used sparingly and only as dictated by the task requirements
(true/false)__________
3>Sensor networks are typically deployed in an adhoc manner (true/false)__________
4>Wireless communication between nodes utilizes radio links (true/false)__________
5>Within the coverage range, communication is by__________ (multicast/broadcast)
6>UDG stands for___________
7>Nodes operate unethered and have limited power resources (true/false)___________
8>For communication, the main consideration is that communication paths consists of many short
hops can be___________ energy efficient than paths using a few long hops (less/more)
9>Networking involves multiple layers in the protocol stack (true/false)___________
10>___________sub-layer manages access to the physical network medium, and its fundamental
goal is to reduce or avoid packet collisions in the medium (MAC/LLC)
11>Following characteristics of wireless sensor networks point to the need for a specialized MAC
protocol
a: the issues of fairness of the node level are much less important than overall application
performance
b: most sensor nodes are idle much of the time
c: In-network processing can greatly improve bandwidth utilization
d: the assumed lack of mobility and therefore the relatively fixed neighborhood of each node can be
exploited in medium access protocol design
e: issues of energy efficiency, scalability and robustness remain paramount
Ans: ___________ (a/b/c/d/e/all)
12>Following MAC protocols have been developed for wireless voice and data communication
networks
a: TDMA
b: FDMA
c: CDMA
d: CSMA
e: WLAN
Ans: __________ (a/b/c/d/e/all)
13>The main goal of the ___________is to reduce energy waste caused by idle listening, collisions,
overhearing and control overhead (S-MAC protocol/IEEE802.15.4 standard)
14>The S-MAC protocol includes following major components
a: periodic listen and sleep
b: collision avoidance
c: overheating avoidance
d: message passing
Ans: ___________ (a/b/c/d/all)
15>In the S-MAC protocol, ___________is designed to reduce energy consumption during the long
idle time when no sensing events happen, by turning off the radio periodically (message
passing/periodic listen and sleep)
16>DCF stands for__________
17>___________in S-MAC is similar to the DCF for IEEE802.11 adhoc mode using an RTS/CTS
exchange (overhearing avoidance/collision avoidance)
18>___________defines both the physical and MAC layer protocols for most remote monitoring and
control as well as sensor network applications (S-MAC protocol/IEEE802.15.4 standard)
19>___________is an industry consortium with the goal of promoting the IEEE802.15.4 standard
(bluetooth/zigbee)
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20>Following are features of Zigbee
a: it is an industry consortium with the goal of promoting the IEEE802.15.4 standard
b: it ensures interoperability by defining higher network layers and application interfaces
c: it is optimized for low data throughput up to 115.2 kbps, with simple or no Qos
support___________
21>Unlike_____, ______achieves its power efficiency from both the physical and MAC layers (S-
MAC protocol/IEEE802.15.4 standard)
22>Following are essential characteristics of current sensor network
a: the nodes have only modest processing power and memory
b: network links and nodes can come and go
Ans: ___________ (a/b/both)
23>___________type protocols only broadcast topology changes to neighbors, but because of that
they converge slowly (link state/distance vector)
24>Proactive protocols of the ___________type need to broadcast to the entire network topology
changes when these are locally detected (LS/DV)
25>Following strategies have been suggested to mitigate the demands of the dynamic changes on
the network
a: the frequency of topology updates to distant parts of the network can be reduced , as in fisheye
state routing
b: reactive protocols can be used instead, constructing paths on demand only. Eg: DSR, AODV
Ans: ___________ (a/b/both)
26>DSR stands for___________
27>AODV stands for___________
28>Following are examples of reactive protocol___________ (DSR/AODV)
29>information providers and information seekers need to be matched usig data attributes and not
hard network addresses (true/false)___________
30>Examples of data attributes may include
a: node's location
b: node's type of sensors
c: certain range of values in a certain type of sensed data
Ans: ___________ (a/b/c/all)
31>The network must be both a database that can be queried about the world state, which is
called_____ operation and an entity that can actively initiate an action when something of interest is
sensed which is called______ (push/pull)
32>Aim of the routing protocols is to deliver packets to nodes or areas of the network specified by
their geographic location (true/false)___________
33>It may be more economical to use a ___________transmission radius for nodes in areas of high
node density (larger/smaller)
34>It may be more economical to use a smaller transmission radius for nodes in areas of high node
density, w/o sacrificing adequate network connectivity. This is the issue of___________ (topology
control/traffic control)
35>In___________ routing, among the neighbors y of x closer to d than x, pick the one closest to d
(greedy distance/compass)
36>In ___________ routing, among the neighbors y of x that make an angle dxy< , we pick one
that minimizes the angle dxy (greedy distance/compass)
37>If G contains the Delaunay triangulation of V, then the ___________protocol always works
(greedy distance/compass/both )
38>___________routing has guaranteed delivery when G Is the Delaunay triangulation of V (greedy
distance/compass/both)
39>___________routing states that "start in the face of G just beyond s along sd and walk around
that face. Stop if d is reached or if the segment sd is about to be crossed. In the latter case, cross
over into the next face of G along sd and repeat the process" (greedy distance/compass /convex
perimeter)
40>OFR stands for ___________
41>In___________ protocol, after we go around a face F, we continue into a new face F' not from
the farthest with F, but instead from the vertex of F closest to d (OFR/perimeter)
42>OAFR stands for___________
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43>We can start with a small guess and double it every time we fail to reach d with our current
guess, until d is reached. This defines adaptive versions of the perimeter protocol
called___________ (OAFR/adaptive perimeter)
44>We say that a sub-graph H of G is a ___________for G if H is a graph on the same vertex set as
G, is missing some of the edges of G, yet there is a constant 'a', a>=1, such that for any pair of
vertices u and v the length of the shortest path between u and v in H is at most 'a' times that of the
length of the shortest path between u and v in G. The constant 'a' is called the__________ (stretch
factor/spanner)
45>A number of the standard geometric graph constructions for a set of points V can be used to
define planarizations of the graph G. The most common such constructions are
___________ (Gabriel/RNG/both)
46>RNG stands for___________
47>In___________, the edges xy is introduced if the lune is free of other nodes (Gabriel/RNG)
48>In___________, the edges xy is introduced if the circle of diameter xy is free of other nodes_
(Gabriel/RNG)
49>_____is a super-graph of the_______ (Gabriel/RNG/both
50>The Delaunay triangulation is known to be___________ of the complete Euclidean graph on V
(planar/spanner/both)
51>RDG stands for___________
52>LDel Stands for___________
53>While ___________protocols are extremely simple, they can get stuck in local minima. In
contrast, ______protocols can provide guaranteed delivery, but require both preprocessing and a
significantly more complex routing algorithm (greedy distance/perimeter)
54>GPSR stands for___________
55>GPSR protocol is a mixture of___________ (greedy distance/perimeter/both)
56>Normally GPSR defaults to ______routing. When it gets stuck, then the_____ protocol is
invoked but only until a node is encountered that is closer to the destination (greedy
distance/perimeter)
57>TBF stands for___________
58>Another form of geographical routing, applicable in a number of dense node coverage settings,
is to specify an ideal curve that a packet should follow, as opposed to the packet's final destination.
This is called___________ (OFR/TBF)
59>___________routing is a method for bringing together information seekers and information
providers in a sensor network (greedy distance/rumour)
60>Following aspects of the energy cost in a sensor network make it challenging to reason about
optimizing energy
a: multi-hop communication can be more efficient than direct transmission
b: when a node transmits, all other nodes within range can hear
Ans: ___________ (a/b/both)
61>Multi-hop communication can be_____ efficient than direct transmission (less/more)
62>The nodes communicate using radio links, where the signal amplitude drops with distance
according to a power law of the form_____ where typically 2<=a<=5{ O (ra
) or O (1/ ra
)}
______
63>In ___________problem, our goal is to find a schedule of broadcasts and retransmissions that
allows the message to reach all nodes while minimizing the total energy expended (minimum energy
broadcast/maximum energy multicast)
64>MST stands for___________
65>The broadcast nature of radio transmissions changes the minimum energy broadcast problem,
as node u transmitting to reach another node v is also reaches all nodes closer than v at no extra
cost. This is called__________ (wireless broadcast advantage/wireless multicast advantage)
66>The minimum energy broadcast problem for both general and geometric graphs is_______
complete (PN/NP)
67>In the worst case , the MST based algorithm gives a broadcast tree whose total energy usage is
between ___&___times the minimum needed (6/12/18)
68>The key idea that establishes the constant factor approximation is a proof that the minimum
energy required for the broadcast problem can be bounded from below by a constant times the
energy cost of the MST based broadcast tree (true/false)___________
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69>BIP stands for___________
70>The BIP works like MST algorithm of___________, adding nodes to the broadcast tree one at a
time, starting with the source (kruskal/prim)
71>GEAR stands for ___________
72>The goal of___________ is to efficiently route a message to a geographic region while at the
same time performing load balancing on the nodes used and thus avoiding energy depletion
(GEAR/GPSR)
73>The GEAR protocol operates in following phases
a: deliver the packet to a node in the desired region
b: distribute the packet within the region
Ans: ___________ (a/b/both)
74>During the ___________ phase, GEAR behaves like a unicast protocol routing the message to
the centroid d of the region R except that it considers the energy resources of each node as well
(delivery/distribution)
75>LRTA stands for___________
76>GEAR provides a__to__% increase in the number of packets transmitted before network
partition, __% increase in the number of connected pairs of nodes after network partition, and the
average increase in the path length taken by a packet due to load balancing was between__&__
(25/45/50/100)
77>The second phase of GEAR deals with packet distribution within the destination region R, once
the packet has reached a node x in the region. One of the following strategies can be used here
a: recursive geographic forwarding
b: restricted flooding
Ans: ___________ (a/b/both)
78>___________refers to a process of recursively partitioning the region R into quadrants and then
forwarding the packet from x to the centroid of each quadrant (restricted flooding/recursive
geographic forwarding)
79>___________refers to the initiating a broadcast flooding process from x that is clipped at the
boundary of R (restricted flooding/recursive geographic forwarding)
80>While____________ has the "wireless multicast advantage", it may till prove wasteful when the
region R is densely populated by nodes and the same packet reaches a node multiple times
(restricted flooding/recursive geographic forwarding)
81>In directed diffusion, nodes requesting information are called___ while those generating
information are called___. Records indicating a desire for certain type of information are called_____
(interests/sinks/sources)
82>wrt directed diffusion, ___________attribute field indicates the frequency with which the sink
wishes to receive information about objects matching the other record attributes
(duration/interval/timestamp)
83>wrt directed diffusion, the period of validity of an interest is encoded in its___________
attribute (duration/interval/timestamp)
84>In directed diffusion, ___________generate information request tasks or interests , that diffuse
through the sensor network (sources/sinks)
85>An essential component of directed diffusion is the use of___________ associated with each
interest cache entry, used to direct and control information flowback to the sink (gradient/gateway)
86>In directed diffusion, a gradient is typically derived from the frequency with which a
___________requests repeated data about an interest (source/sink)
87>In data____ type, all communications happened because of the sink's request while in data
_______type, directed diffusion lets sensor nodes trigger event propagation when they detect
something that they believe might be of interest to potential sinks (push/pull)
88>Directed diffusion provides a general-purpose communication mechanism for sensor networks
(true/false)___________
89>Directed diffusion is___________ centric in its network view and performs all routing decisions
through local, neighbor-to-neighbor interactions (state/node)
90>Directed diffusion provide a___________ routing technique, discovering routes between
information sources and sinks as needed (proactive/reactive)
91>Directed diffusion can effectively suppress duplicate events and perform in-network information
aggregation (true/false)___________
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92>There are may situations in which, because the amount of data to be exchanged is small, the
quality of the paths does not matter so much. In such situations, ___________routing can be used
(rumour/reactive)
93>In___________ routing, in order to get sources and sinks to meet each other, we must spread
information from each regions of the sensor field, so that the two growing regions eventually
intersect (rumour/reactive)
94>Related to rumour routing is the___________ query answering mechanism (ACQUIRE/ACCESS)
95>In rumor routing, ___________approach is most appropriate for situations when we need to
process one-shot complex queries, whose answers depend on information obtained in several nodes
of the network (ACQUIRE/ACCESS)
96>wrt rumour routing, the idea of the ___________system is to elect a leader node whose goal is
to compute the answer to the query (ACQUIRE/ACCESS)
97>IDSQ stands for___________
98>GHT stands for___________
99>GHT is a robust protocol (true/false)___________
100>One of the most elegant aspects of GHT is the way that it exploits features of the___________
routing protocol accomplish its goal (GEAR/GPSR)
101>A nice feature of the perimeter refresh protocol is that it helps to recover from node failures
(true/false)__________
102>In wireless sensor network, the issues of fail utilization of networking resources at the node
level are__________ important than just accomplishing the overall goal(less/more)
103>What is important to the sensor network is the information the nodes contain, not the nodes
themselves (true/false)__________
104>In wireless sensor networks, nodes are ephemeral i.e. they can be destroyed, be asleep or die
from malfunction or battery depletion (true/false)__________
105>Preservation of energy is of paramount concern in wireless sensor network
(true/false)__________
106>Network for sensor networks is ____centric but not ______centric (node/data)
107>GHT uses a perimeter refresh protocol
a: to accomplish replication of attribute-value pairs
b: to ensure their consistent placement in the appropriate home node
c: to recover from node or link failures
Ans: ___________ (a/b/c/all)
ANSWERS
1>T
2>T
3>T
4>T
5>broadcast
6>Unit Distance Graph
7>T
8>more
9>T
10>MAC
11>all
12>all
13>S-MAC
14>all
15>periodic listen & sleep
16>Distributed Coordinate Function
17>collision avoidance
18>IEEE 802.15.4
19>ZigBee
20>all
21>S-MAC, 802.15.4
22>both
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23>LS
24>DV
25>both
26>Dynamic Source Routing
27>Adhoc On-demand Distance Vector Routing
28>both
29>T
30>all
31>pull, push
32>T
33>smaller
34>topology control
35>greedy distance
36>compass
37>greedy distance
38>both
39>convex
40>Other Face Routing
41>OFR
42>Other Adoptive Face Routing
43>both
44>spanner, stretch factor
45>both
46>Relative Neighborhood Graph
47>RNG
48>Gabriel
49>Gabriel, RNG
50>both
51>Restricted Delaunay Graph
52>Localized Delaunay Triangulation
53>greedy distance, perimeter
54>Greedy Perimeter Stateless Routing
55>both
56>greedy distance, perimeter
57>Trajectory Based Forwarding
58>TBF
59>rumor
60>both
61>more
62>O(1/ ra
)
63>minimum energy broadcast
64>Minimum Spanning Tree
65>wireless multicast advantage
66>NP
67>6,12
68>T
69>Broadcast Incremental Power
70>Prim
71>Geographical & Energy Aware Routing
72>GEAR
73>both
74>delivery
75>Learning Real Time A
76>50,100,50,25,45
77>both
78>recursive geographic forwarding
79>restricted flooding
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80>restricted flooding
81>sink, source, interest
82>interval
83>duration
84>sink
85>gradient
86>sink
87>pull, push
88>T
89>data
90>reactive
91>T
92>rumor
93>rumor
94>ACQUIRE
95>ACQUIRE
96>ACQUIRE
97>Information Driven Sensor Querying
98>Geographic Hash Table
99>T
100>GPSR
101>T
102>less
103>T
104>T
105>T
106>data, node
107>all
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CHAPTER 4: INFRASTRUCTURE ESTABLISHMENT
1>The problem of__________ for a sensor network is how to set the radio range for each node so
as to minimize energy usage, while still ensuring that the communication graph of the nodes
remains connected and satisfies other desirable communication properties (topology control/traffic
monitoring)
2>CTR stands for__________
3>__________problem states "compute the minimum common transmitting range r such that the
network is connected" (topology control/critical transmitting range)
4>The probabilistic theory best suited to the analysis of CTR is the theory of __________
(GRG/GLS)
5>GRG stands for__________
6>In__________ setting, n points are distributed into a region according to some distribution, and
then some aspect of the node placement is investigated (GRG/GLS)
7>If n points are randomly and uniformly distributed in the unit square, then the critical
transmission range is, with high probability
a: r=c.sqrt (n/logn)
b: r=c.sqrt (logn/n)
Ans: ___________ (a/b/either)
8>One should choose_____ ranges in areas of high node density and ______ranges in regions of
low density (short/long)
9>The range assignment problem has been shown to be NP complete for dimensions __& above
(1/2)_________
10>___________MST based algorithms can be expensive to implement on typical sensor nodes
(homogeneous/non-homogeneous/either)
11>Give example of protocol that can be used to directly solve the CTR problem in a distributed
way: ___________ (COMPOW/COMPASS)
12>__________protocol computer routing tables of each node at different power levels and a node
selects the minimum transmit power so that its routing table contains all other nodes
(COMPOW/COMPASS)
13>___________allows hierarchical structures to be built on the nodes and enables more efficient
use of scarce resources such as frequency spectrum, bandwidth and power (clustering/classification)
14>___________allows the same time or frequency division multiplexing to be reused across non-
overlapping clusters (clustering/classification)
15>The more capable nodes can naturally play the role of __________ (cluster leader/cluster head)
16>__________are nodes that aid in passing traffic from one cluster to another (gradient/gateway)
17>___________can be used to thin out parts of the network where an excessive number of nodes
may be present (classification/clustering)
18>Since the nodes in a sensor network operate independently , their clocks may not be or stay,
synchronized with one another (true/false) ___________
19>For time synchronization, the wired protocols assume the existence of highly accurate master
clocks on some network nodes such as ___________ (skew clock/atomic clock)
20>In wireless sensor network
a: no special master clocks are available
b: connections are ephemeral
c: communication delays are inconsistent and unpredictable
Ans: ___________ (a/b/c/all)
21>Computer clocks are based on ___________oscillators which provide a local time for each
sensor network node (software/hardware)
22>For a perfect hardware clock, the derivative dC (t)/dt should be___ to 1 (=/</>)
23>wrt clocks and communication delays, a typical value of p for today's hardware clock is 10-__
(3/6/9)
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24>___________can actually change over time due to environmental conditions such as
temperature and humidity (clock atomic/clock skew)
25>Time difference caused by the lack of a common time origin are referred to as___________
(clock phase difference/clock bias)
26>The latency in channel can be decomposed into following components
a: send time
b: access time
c: propagation time
d: receive time
Ans: ___________ (a/b/c/d/all)
27>Match the following
Send time: this is the delay incurred while waiting for access to the transmission channel due to
contention, collisions etc
Access time: this is the time for message to travel across the channel to the destination node
Propagation time: this is the time for the network interface on the receiver side to get the message
and notify the host of its arrival
Receive time: this is the time taken by the sender to construct the message ___________
28>___________delay can be kept small by time stamping the incoming packet initiate the network
driver's interrupt handler (receive time/send time/propagation time/access time)
29>Time synchronization can be propagated across the network by using a ___________tree
favoring direct connections with reliable delays (binary/spanning)
30>In many situations involving temporal reasoning, the temporal ordering of events matters
______than the exact times when events occurred (less/more)_____
31>___________methods provide a lightweight protocol that can be used to move clock readings
around the network and perform temporal comparisons (interval/reference)
32>Time comparisons are not sufficient for all applications and mappings from event times to time
intervals may quickly become useless if ___________increase the interval sizes beyond reasonable
limits (long delay/multi-hop route/either)
33>RBS stands for___________
34>The key idea of the ___________is to use the broadcast nature of the wireless communication
medium to reduce delays and delay uncertainty in the synchronization protocol (interval
method/RBS)
35>___________refers to the maximum offset between any pair of receiver nodes (group
interval/group dispersion)
36>One way to estimate ___________among pairs of receivers is to do a least-squares linear
regression among all the pair-wise measurements obtained for the two receivers in a sequence of
reference broadcasts (clock skew/phase difference)
37>___________is a method that allow the nodes in a network to determine their geographic
positions on their own as much as possible, during the network initialization process (self
tracking/self localization)
38>___________is a method that allows other nodes to obtain the location of a desired node, after
the initial phase in which each node discovers its own location (tracking service/location service)
39>The nodes that know their positions are called___________ (locatable/landmark)
40>Drawbacks of GPS
a: GPS receivers can be expensive and difficult to incorporate into every sensor node for a number
of practical reasons including cost, power consumption, large form factors
b: GPS systems do not work indoor or under ford foliage or in other expectable conditions
Ans: ___________ (a/b/both)
41>___________methods aim at estimating the distance of a receiver to a transmitter , by
exploiting known signal propagation characteristics (interval/ranging)
42>RSS stands for___________
43>___________technique can be used to estimate the RF signal strength at the receiver
(RSS/RBS)
44>in general, localization to within a few meters is the best that can currently be attained
with___________ methods (RSS/RBS)
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45>A way to estimate distance is to measure the time it takes for a signal to travel from sender to
receiver, this can be multiplied by the signal propagation speed to yield distance. Such methods are
called___________ technique (TDOA/TOA)
46>Since the exact time of transmission may be hard to know, a way to estimate distance is to
measure the ___________at two receivers, which then lets us estimate the difference in distances
between the two receivers and the sender (TDOA/TOA)
47>Local pairs of beacons can be used to estimate local propagation speed (true/false)___________
48>___________is similar to the collaborative source localization (atomic multi-lateration/attribute
based routing)
49>Collaborative multi-lateration proceeds by computing substructures of the network
called___________ (spanning tree/collaborative sub-tree)
50>___________are sub-graphs of the full network graph in which there are enough constraints to
make the localization problem sufficiently overdetermined that error accumulation is avoided
(spanning tree/collaborative subtree)
51>Collaborative subtrees are built using the notion of ___________nodes (tentatively
unique/temporally unique)
52>A node is called___________ during a multilateration sequence if its position can be uniquely
determined , assuming the positions of the other nodes used as references are unique (tentatively
unique/temporally unique)
53>___________algorithm is used to traverse the network from a given node and accumulate
nodes that can form a collaborative subtree (regression/recursive)
54>APIT stands for___________
55>___________test can be used for range-free localization (APIT/ADIT)
56>For any triplet of landmarks that a node can hear, if the node passes the___________ test with
respect to these landmarks , then the node is declared to be in the triangle defined by the landmarks
(APIT/ADIT)
57>APIT failures happen less than___% of the time (14/15/16)________
58>___________is a mechanism for mapping from node IDs of some sort to node locations
(tracking service/location service)
59>The Grid system uses a distributed location service termed___________ (GLS/GRG)
60>The key idea of___________ is to distribute the load so that each network node acts as a
location server for a relatively small number of other nodes, most in its neighborhood (GLS/GRG)
61>___________provides a mapping from node IDs to node locations (GLS/GRG)
62>In GLS, if we have n nodes that are reasonably uniformly distributed in a field , then the depth
of the quad-tree will be___________{O (logn) or O (logn+1)}
63>Nodes can be aggregated into clusters
a: to better share resources, control redundancy
b: to enable hierarchical tasking and control
Ans: ___________ (a/b/both)
64>___________remain especially challenging problems in the adhoc deployment setting
(synchronization/localization/both)
65>In location dependent systems such as the___________ indoor system, beacons in each room
broadcast location information to listener nodes (cricket/hockey)
ANSWERS
1>topology control
2>Critical Transmitting Range
3>CTR
4>GRG
5>Geometric Random Graph
6>GRG
7>b
8>short, long
9>2
10>ether
11>COMPOW
12>COMPOW
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13>clustering
14>clustering
15>cluster head
16>gateway
17>clustering
18>T
19>atomic clock
20>all
21>hardware
22>equal
23>6
24>clock skew
25>either
26>all
27>1-d 2-a 3-b 4-c
28>receive time
29>spanning
30>more
31>interval
32>either
33>Reference Broadcast System
34>RBS
35>group dispersion
36>both
37>self-localization
38>location service
39>landmark
40>both
41>ranging
42>Received Signal Strength
43>RSS
44>RSS
45>TOA
46>TDOA
47>T
48>atomic multi=lateration
49>collaborative subtree
50>collaborative subtree
51>tentatively unique
52>tentatively unique
53>recursive
54>Approximate Point In Triangle
55>APIT
56>APIT
57>14
58>location service
59>GLS
60>GLS
61>GLS
62>O(log n)
63>both
64>both
65>cricket
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CHAPTER 5: SENSOR TASKING AND CONTROL
1>_____sensor can be tasked to look for animals of a particular size and color. _____sensor can be
tasked to detect the presence of a particular type of vehicle (acoustic/camera)
2>IDSQ stands for__________
3>The purpose of a sensor system is to obtain information that is as extensive and detailed as
possible about the unknown parts of the world state (true/false)__________
4>When we know the relevant manifest variables defining the world state, then computing the
answers to queries about the world state is a__________ problem (standard algorithm design/range
assignment)
5>The standard algorithm design problem needs to be modified in the sensor network context
because
a: the values of the relevant manifest variables are not known but have to be sensed
b: the cost of sensing different variables or relations of the same type can be vastly different
c: frequently the value of a variable or a relationship between variables, may be impossible to
determine using the resources available in the sensor network
ns: __________ (a/b/c/all)
6>The online nature of sensing requires the use of methods such as___________ to account for the
fact that the value of sensor readings cannot be known before they are made (competitive
analysis/value of information/either)
7>The main idea of information based sensor tasking is to base sensor selection decisions on
information content as well as constraints on resource consumption, latency and other costs
(true/false)___________
8>___________formulates the sensor tasking problem as a general distributed constrained
optimization that maximizes information gain of sensors while minimizing communication and
resource usage (IDSQ/IBST)
9>___________refers to the knowledge about the target state such as position and velocity (belief
state/true state)
10>Following approaches can be used for localizing a stationary source and tracking a moving
source
a: a leader node might act as a relay station to the user, in which case the belief resides at this node
for an extended time interval, and all information has to travel to this leader
b: the belief itself travels through the network, and nodes are dynamically assigned as leaders
Ans: ___________ (a/b/both)
11>Using___________ criterion, the leader node at the center always selects the nearest node
among those whose measurements have not been incorporated (NP/NN)
12>__________based selection favors sensors along the longer axis of the covariance fit of residual
uncertainty in localization (mutual information/Mahalanobis)
13>In __________sensor network systems, we must balance the information contribution of
individual sensors against the cost of communicating with them (centralized/distributed)_
14>For multimodal, non-Gaussian distributions, ___________measure provides a better
characterization of the usefulness of sensor data (mutual information/Mahalanobis)
15>___________can be interpreted as the Kullback Leibler divergence between the belief after and
before applying the new measurement (mutual information/Mahalanobis)
16>The appropriateness of a particular utility measure for a sensor selection problem depends on
following factors
a: the characteristics of the problem such as the data and noise models
b: the computational complexity of computing the measure
Ans: __________ (a/b/both)
17>_____measure is easy to compute, although limited to certain data models.______applies to
multimodal distributions, but its computation requires expensive convolution of discrete points if one
uses a grid approximation of probability density functions (mutual information/Mahalanobis)
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18>___________method is based on the cluster leader type of distributed processing protocol
(IDSQ/IBST)
19>In IDSQ algorithm, arrange following steps in correct order
a: follower nodes
b: initial sensor reading
c: initialization
d: sensor selection
e: belief quality
Ans: ___________ (cbaed/cabde/cabed)
20>In the___________ based protocol , it is necessary to design efficient and robust algorithms for
electing a leader, since typically more than one sensor may have detections about a target
simultaneously (planar/leader)
21>In leader election protocol, arrange the following steps in correct order
a: if there are one or more messages with an earlier time stamp, the node knows that it is not the
leader
b: if none of the messages contains earlier time stamps, but some message contains a time stamp
identical to the node's detection time, the node compares the likelihood ratio.If the node's likelihood
ratio is higher, the node becomes the leader
c: if none of the messages is time stamped earlier than the node's own detection, the node declares
itself leader
Ans: ________ (bca/cba/cab)
22>In the leader based protocol, following different criteria can be used for choosing the next sensor
a: nearest neighbor
b: mahalanobis distance
c: maximum likelihood
d: best feasible region
Ans: ___________ (a/b/c/d/all)
23>PIR stands for___________
24>NN stands for___________
25>A primary purpose of sensing in a sensor network is to collect and aggregate information about
a phenomenon of interest (true/false)___________
26>___________provides us with a method of selecting the optimal order of sensors to obtain
maximum incremental information gain (IDSQ/IBST)
27>A user issues a query from an arbitrary node, which is called as___________ node, requesting
the sensor network to collect information about a phenomenon of interest (query proxy/query
processing)
28>Using the___________ measure, the querying node can determine which node can provide the
most useful information while balancing the communication cost, w/o the need to obtain the remote
sensor data first (mahalanobis distance/mutual information)
29>In a ___________belief carrier protocol, the belief is successively handed off to sensor nodes
closest to locations where useful sensor data are being generated (static/dynamic)
30>In___________ belief carrier protocol, the current sensor node updates the belief with its
measurement and sends the estimation to the next neighbor that it determines can best improve the
estimation (static/dynamic)
31>The___________ algorithm fails due to its lack of knowledge beyond the immediate
neighborhood (greedy/recursive)
32>Example of local routing algorithm is___________ (GPSR/GPRS)
33>In general, the information contribution of each sensor is state-dependent
(true/false)___________
34>Following are examples of standard shortest path algorithms on graphs___________
(dijkstra/bellman ford/both)
35>MSE stands for___________
36>The error in localization, measured as mean squared error , generally ___________as more
sensor measurements are incorporated (increases/decreases)
37>State dependency is an important property of sensor data aggregation, regardless of specific
choices of information metrics (true/false)___________
38>Search cost function is defined as the path cost___________ the information gain (plus/minus)
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39>To mitigate the combinational explosion problem, following strategies can be used
a: we can restrict the search for optimal paths to a small region of the sensor network
b: we can apply heuristics to approximate the costs so that they can be treated as additive
Ans: ___________ (a/b/either)
40>In sensor network, the goal is to route a query from the query proxy to the exit point and
accumulate as much information as possible along the way, so that one can extract a good estimate
about the target state at the exit node and yet keep the total communication cost close to some
prespecified amount (true/false)___________
41>When it is possible to estimate the cost to go, the A* ___________method can be used (best
first search/heuristic search)
42>The basic A* is a ___________search, where the merit of a node is assessed as the sum of the
actual cost g paid to reach it from the query proxy , and the estimated cost h to pay to get to the
exit node (depth first/best first)
43>For real-time path-finding, we use a variation of the A* method called ___________search
(RTA/BFS)
44>RTA stands for___________
45>In many applications, the physical phenomenon may be mobile, requiring the network to
migrate the information according to the motion of the physical phenomenon for
communication___________ reasons (efficiency/scalability/both)
46>In practical applications, the effect of a physical phenomena usually attenuates with distance,
thus limiting the propagation of physical signals to geographical regions around the physical
phenomenon (true/false)___________
47>The physical phenomenon being sensed change over time (true/false)___________
48>Geographically based group initiation and management have to be achieved by a___________
protocol distributed on all sensor nodes (greedy/lightweight)
49>Considering that the group membership is dynamic as the targets move and that the network is
formed in an adhoc way such that no nodes have the knowledge of the global network topology.
These difficulties may be tackled via following techniques
a: leader based tracking algorithm where at any time each group has a unique leader who knows the
geographical region of the collaboration
b: recent advances in geographical routing that do not require the leader to know the exact
members of its group
Ans: ___________ (a/b/both)
50>The information based approach to sensor querying and data routing selective invokes sensors
to___________ the number sensing actions needed for a given accuracy and hence latency &
energy usage (minimize/maximize)
51>___________is a set of sensor nodes responsible for the creation and maintenance of a target's
belief state over time, which we call track (co-operative group/collaborative group)
52>is a set of sensor nodes responsible for the creation and maintenance of a target's belief state
over time, which we call ___________ (trunk/track)
53>How the leader node maintains and migrates the collaborative processing group. Arrange the
following steps in correct order
a: sensors are selected to acquire new measurements using the sensor selection algorithm
b: after the leader is elected, it initializes a belief state as uniform disk centered at its own location_
c: as the target moves, the sensors that did not previously detect may begin detecting
Ans: __________ (cba/acb/bca)
54>Following are examples of data association algorithms
a: optimal assignment
b: multiple hypothesis processing
Ans: ___________ (a/b/both)
55>Using ___________algorithm , the ambiguities in the target identities after crossing tracks can
be resolved using additional local evidence of the track identity and then propagate the information
to other relevant tracks (identity management/data association)
56>We can convert global estimation and tracking problem into a local analysis using the so
called___________ (primal dual transformation/parametric approximation)
57>A wireless sensor network is severely constrained by the on-board battery power
(true/false)___________
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58>If a sensor only wakes up, senses and communicates when it expects an event of interest, the
power consumption of the network could be dramatically reduced (true/false)___________
59>The idea of information driven sensor tasking, and its realization in IDSQ, is to base the sensor
selection the potential contribution of a sensor to the current estimation task while using a moderate
amount of resources (true/false)___________
60>Following protocol can be used for sensing stationary or moving physical phenomena
a: leader based
b: moving center of aggregation
Ans: ___________ (a/b/both)
61>In the resource limited sensor networks, the appropriate balance between the information and
the costs is of paramount concern, since unnecessary data collection or communication consumes
precious bandwidth and energy and overload human attention (true/false)___________
62>Primary function of a senor network is to collect information from a physical environment
(true/false)___________
63>Routing an a sensor network must be co-optimized with the information aggregation or
dissemination (true/false)___________
64>___________group is an important abstraction of physical sensors, since individual sensors are
ephemeral and hence less important, and sensors collectively support a set of tasks (co-operative
processing/collaborative processing)
65>A major benefit of establishing the collaborative group abstraction is in enabling the
programming of sensor networks to move from addressing individuals nodes to addressing
collectives (true/false) ___________
ANSWERS
1>camera
2>Information Driven Sensor Querying
3>T
4>standard algorithm design
5>all
6>either
7>T
8>IDSQ
9>belief
10>both
11>NN
12>Mahalanobis
13>distributed
14>mutual information
15>mutual information
16>both
17>Mahalanobis , mutual information
18>IDSQ
19>cabed
20>leader
21>cab
22>all
23>Passive Infrared
24>nearest-neighborhood
25>T
26>IDSQ
27>query proxy node
28>Mahalanobis
29>dynamic
30>dynamic
31>greedy
32>GPSR
33>T
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34>both
35>Mean Squared Error
36>decreases
37>T
38>minus
39>either
40>T
41>heuristic search
42>best first
43>RTA
44>Real Time A*
45>both
46>T
47>T
48>lightweight
49>both
50>minimize
51>collaborative group
52>track
53>bca
54>both
55>identity management
56>spinal-dual transformation
57>T
58>T
59>T
60>both
61>T
62>T
63>T
64>collaborative processing
65>T
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CHAPTER 6: SENSOR NETWORK DATABASES
1>From a data storage point of view ,one may think of a sensor network as a distributed database
that
a; collects physical measurements about the environment
b; indexes them
c; serves queries from users and other applications external to or from within the network
Ans; __________ (a/b/c/all)
2>The advantage of the database approach is that it provides a separation between the logical view
of the data held by the sensor network and the actual implementation of these operations on the
physical network (true/false)__________
3>In a classical DBMS ,data is stored in a__________ location (centralized/distributed)
4>The structure and constraints of the data format are called database__________ (table/schema)
5>The database scheme are typically defined or modified by a database administrator using
__________ (DML/DDL)
6>DDL stands for___________
7>Today most databases employ relational schemas and their variants, organizing data into tables
whose_____ are record tuples and whose______ are labeled by data attributes rows/columns)
8>___________compiler translates the definitions into metadata which is stored in permanent
storage along with the actual data (DML/DDL)
9>___________is a data structure describing the structure of the database data and the constraints
they must satisfy (metadata/temporal data)
10>In a typical database system ,the___________ directly controls storage devices such as disks
and the flow of data between them and main memory (storage & buffer manager/transaction
manager )
11>The database is updated through units of work named___________ (transition/transaction)
12>It is the job of the__________ to guarantee that transactions are executed atomically and in
apparent isolation from other transactions (storage & buffer manager/transaction manager)
13>A user queries the database in a high level logical query language such as___________
(Oracle/SQL)
14>A query is parsed by the_____ and translated into an optimized execution plan ,which is then
processed by the______ to answer the user query (execution engine/query processor)
15>In any database system, there are trade offs between the speed of answering queries and the
speed of performing database updates (true/false)___________
16>In__________ database systems ,data storage may be allocated among several geographical
separated locations ,connected by a communications network (centralized/distributed)
17>___________database makes the job of the query processor significantly harder
(centralized/distributed)
18>Most query execution plans can be represented as trees where the_____ represent database
operators and the______ correspond to producer-consumer relationships among operators
(centralized/distributed)
19>P2P Stands for___________
20>In___________ networks ,active processors can number in the tens to hundreds of thousands
and may come on the network and go off the network at arbitrary times (P2P/PPP)
21>Another recent trend in database systems is to consider systems for data streams. Such systems
are aimed at handling long running___________ queries such as may arise in network or traffic
monitoring ,telecom call ,stock market transaction or web log record summarization
(continuous/discontinuous)
22>Each sensor in a sensor network takes___________ measurements of physical phenomena such
as heat, sound, light ,pressure or motion (time sequenced/time stamped)
23>The issue of where to store the data becomes of paramount importance since_____
dominates______ (energy landscape/communication cost)
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24>Following approaches can be used for implementing databases to support sensor network
a; transfer all the data to one or a small number of external warehouses ,where traditional DBMS
system could be deployed
b; store the data within the network itself and allow queries to be injected anywhere in the network
Ans; ___________ (a/b/both)
25>At the physical level, there are following major distinguishing characteristics of sensor networks
when it comes to database implementation
a; the network replaces the storage and buffer manager--data transfers are from data held in node
memory as opposed to data blocks on disk
b; node memory is limited by cost and energy considerations
Ans; ___________ (a/b/both)
26>Following are challenges in sensor network databases
a; the system as a whole is highly volatile
b; relational tables are not static since new data is continuously being sensed
c; the high energy cost of communication encourages in-networking processing during query
execution
d; access to data may be hampered by arbitrarily long delays and the rates at which input data
arrives to a database operator can be highly variable
Ans; ___________ (a/b/c/d/all)
27>Following are challenges in sensor network databases
a; limited storage on nodes and high communication costs imply that older data has to be discarded
b; sensor tasking interacts in numerous ways with the sensor database system
c; classical metrics of database system performance ,such as throughput or delay may have to be
adjusted in the sensor network context because of high variance in these quantities
Ans; ___________ (a/b/c/all)
28>Following are differences between sensor network data and those of other databases at the
logical level
a; sensor network data consists of measurements from the physical world
b; additional operators have to be added to the query language to specify durations and sampling
rates for the data to be acquired
c; while single shot queries are possible and useful in sensor networks ,we expect that a good
fraction of the queries will be of the continuous ,long running type such as monitoring the average
temperature in a room
d; it is important to have operators for correlating sensor readings and comparing them with past
statistics
Ans; ___________ (a/b/c/d/all)
29>Sensor network differs from__________ networks in that nodes operate with limited energy
,processing and memory resources (data streams/P2P)
30>Sensor network differs from ___________networks in that geographic location can be of great
importance in deciding what information to store and what information to query for (data
streams/P2P)
31>It is advantageous to express queries to a sensor network database at a logical, declarative level
,using relational languages such as SQL (rue/false)___________
32>In querying the physical environment ,___________level interfaces allow nonexpert users to
easily interact with the database (low/high)
33>_____clause specifies the period during which data is to be collected, and the______ clause
specifies the frequency at which the query results are returned (sampling period/duration)
34>There may be____ queries such as the report results over an extended time window ,___queries
concerning the data in the network at a given point in time and____ queries that ask for aggregate
information over historical data (snapshot/historical/continuous)
35>The queries on sensor networks may
a; aggregate data over a group of sensors or a time window
b; contain conditions restricting the set of sensors from contributing data
c; correlate data from different sensors
d; trigger data collection or signal processing on sensor nodes
e; spawn subqueries as necessary
Ans; ___________ (a/b/c/d/e/all)
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36>Not all users of a database system will be human operators (T/F)___. Programs running on the
nodes themselves may generate queries in order to decide what sensing actions a node should take
(T/F)___
37>___________sensor network database system maintains an SQL-type query interface for users
at a front end server connected to a sensor network (courage/cougar)
38>Distributed query execution is optimized for___________ (resource usage/reaction time/both)
39>Cougar represents each type of sensor in a network as an___________ ,as in most modern
object-relational databases (ASN/ADT)
40>In Cougar database ,___________provides controlled access to encapsulated data through a
well defined set of access functions (ASN/ADT)
41>An ADT object in the Cougar database corresponds to a___________ sensor in the real world
(logical/physical)
42>STFT stands for___________
43>The public interface of a seismic sensor ADT can comprise signal processing functions such as
a; STFT
b; vibration signature analysis
Ans; ___________ (a/b/both)
44>___________relations are relations that are not actually materialized as ordinary table
(base/virtual)
45>Cougar introduces_____ relations in contrast to the______ relations defined in the database
schema (base/virtual )
46>Cougar considers___________ query processing in the network (centralized/distributed)
47>Sensor data invariably contains measurement uncertainty due to ___________ (device
noise/environmental perturbation/either)
48>GADT stands for___________
49>___________models the uncertainty as a continuous probability distribution function over
possible measurement values (ADT/GADT)
50>An operation named___________ primitive allow for probabilistic equality tests ,so one can
meaningfully compare different Gaussian variables (Prob/Conf/Diff)
51>Range queries are another important class of sensor network queries (true/false)___________
52>In the___________ warehousing approach ,each sensor forwards its data to a central server or
warehouse connected to the network via an access point (centralized/decentralized)
53>Following are disadvantages of centralized warehousing
a; the nodes near the distinct point become traffic hot spots and central points of failure plus they
may be depleted of energy prematurely
b; this approach does not take advantage of in-network aggregation of data to reduce the
communication load when only aggregate data needs to be reported
c; sampling rates have to be set to be the highest that might be needed for any potential query
,possibly further burdening the network with unnecessary traffic
d; customers of the data may be other applications running on nodes themselves in the network
Ans; ___________ (a/b/c/d/all)
54>In___________ approach, the data is stored within the network (centralized warehouse/in-
network storage)
55>At the center of the___________ design is the appropriate choice of storage points for the data
,which act as rendezvous points between data and queries ,so that the overhead to store and access
the data is minimized and the overall load is balanced across the network (centralized warehouse/in-
network storage)
56>Features of the in-network storage
a; allows data to be aggregated before it is sent to an external query
b; takes advantage of locality of information for in-network queries
c; load-balances the database costs across the nodes
Ans; ___________ (a/b/c/all)
57>Following metrics can be used for general database systems
a; network usage b; preprocessing time
c; storage space requirement d; query time
e; throughput f; update & maintenance cost
Ans; ___________ (a/b/c/d/e/f/all)
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58>Match the following
network usage; the time taken to construct an index
preprocessing time; the storage for the data and index
storage space requirement; the time taken to process a query ,assemble an answer ,and return this
answer
query time; the average number of queries processed per unit of time
throughput; costs such as processing sensor data ,insertions ,dejections or repairs when nodes fail
update & maintenance cost; it is characterized by total usage and hot spot usage
59>Network usage is characterized by______ which refers to the total number of packets sent in
the network and_____ which refers to the maximal number of packets processed by any particular
node (hot spot usage/total usage)
60>A sensor network database differs from a traditional centralized system in that
a ; resources are severely constrained
b; query processing is tightly coupled with networking and application semantics
Ans; ___________ (a/b/both)
61>When designing a sensor database, we desire he following properties
a; persistence
b; consistency
c; controlled access to data
d; scalability in network size
e; load balancing
f; topological generality
Ans; ___________ (a/b/c/d/e/f/all)
62>Match the following
Persistence; the database architecture should work well on a broad range of network topologies
Consistency; as the number of nodes increases ,the system's total storage capacity should increase
Controlled access to data; a query must be routed correctly to a node where the data are currently
stored
Scalability in network size; data stored in the system must remain available to queries, despite
sensor node failures and changes in the network topology
Load balancing; different update operations must not undo one another's work ,and queries must
always see a valid state of the database
Topological generality; storage should not unduly burden any one node nor should any node become
a concentration point of communication
63>In-network query processing can be used to provide substantial energy savings when serving
aggregate queries. This saving is possible because
a; separating data at intermediate nodes reduces the overall number of messages the network has
to transmit ,thus reducing communication and prolonging the lifetime of the network
b; combining data at intermediate nodes reduces the overall number of messages the network has
to transmit ,thus reducing communication and prolonging the lifetime of the network
Ans; ___________ (a/b/both)
64>In the___________ based approach ,the aggregation occurs at an external server ,each sensor
sends its data directly to the server (client/server)
65>In-network aggregation and query processing typically involve___________ (query
propagation/data aggregation/both)
66>A key challenge for in-network aggregation is the design of an optimal data aggregation
schedule that is___________ efficient (energy/time/both)
67>___________provides an SQL-style declarative query interface, and implement aggregation
mechanisms that are sensitive to resource constraints and loopy communication (TinyOS/TinyOS)
68>TinyDB supports following SQL operators
a; count
b; min
c; max
d; sum
e; average
Ans; ___________ (a/b/c/d/e/all)
69>TinyDB supports following extensions___________ (median/histogram/both)
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70>For______ operator, it can be shown that the size of the partial state record is proportional to
the size of the data set it summarizes ,while in_____ operator ,the size correlates with statistical
properties (median/histogram)
71>___________are distributive ,meaning the size of an intermediate state is the same as that of
the final aggregate__________ is algebraic in that the partial state records are not themselves
aggregates for the data set ,but are of constant size (max/min/count/average/sum)
72>_____is holistic and______ is content sensitive (median/histogram)
73>The performance of TinyDB is___________ related to the amount of intermediate state
information required per aggregate (directly/inversely)
74>TinyDB uses ___________ based mechanism for data aggregation (emoge/epoch)
75>TinyDB builds a___________ tree for aggregation (static/dynamic)
76>In the query tree ,_____are the operators and______ are data dependencies among the
operators (nodes/edges)
77>The task assignment problem is___________ complete (NP/PN)
78>A tree based query propagation mechanism is appropriate for a ___________based application
(client/server)
79>DCS stands for___________
80>____________is a method proposed to support queries from any node in the network by
providing a rendezvous mechanism for data and queries that avoids flooding the entire network
(DCE/DCS)
81>Directed diffusion is an example of data centric routing (true/false)___________
82>At the center of a DCS system are___________ points ,where data and queries meet
(rendezvous/meeting)
83>GHT stands for___________
84>An instance of DCS is the ___________ (GLS/GHT)
85>in___________ ,the translation from node attributes to storage location is accomplished by a
hash function ,which attempts to distribute data evenly across the network (GLS/GHT)
86>___________may be regarded as a variant of publish and subscribe except the event broker
serves as the data storage and rendezvous point (DCS/DCE)
87>A type of query that is especially appropriate for sensor network databases is a
__________query (range/boundary)
88>In___________ query ,a certain range is specified for a number of attributes of interest on the
data sought (range/boundary)
89>In general ,sensor network data is multi-attribute (true/false)___________
90>__________is aimed at point queries or exact matches, so it is not well suited for queries
involving data ranges (GLS/GHT)_
91>in general ,the complexity of answering a query in a sensor network will be a function of
a; the size of the data in the network
b; the number of records returned
Ans; ___________ (a/b/both)
92>Following are classical measures of the quality of an index___________ (speed/size/both)
93>The ___________data the index stores ,the faster the query processing can be (less/more)
94>wrt one dimensional indices ,the particular subsets of data forming the prestored answers are
referred to as the___________ subsets (orthogonal range/canonical)
95>In canonical subsets of sensors along a road ,an___________ node in the tree aggregates
information from all its descendant sensors in th tree (internal/external)
96>Partial data aggregation is a key feature of any indexing scheme for range searching
(true/false)___________
97>When we have a set of attributes each parameterized by a scalar value and query with a interval
along a subset of the parameters ,then we call this as___________ searching (orthogonal
range/canonical)
98>Examples of hashing/partitioning schemes are___________ (grid files/partitioned hashing/both)
99>Examples of tree based index structure include
a; multilevel indices b; k-d trees
c; quad tree d; R trees
Ans; ___________ (a/b/c/d/all)
100>The storage cost for storing m events into ___________is O (m) {k-d tree/multi level}
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101>Range searching indices provide a hierarchical summarization of records or events in the
database according to simple attributes of interest (true/false)__________
102>Wavelet transforms provide one way to compress and summarize information for both temporal
and spatial signals ,and are widely used in__________ processing (signal/image/both)
103>__________is a system that provides multi-resolution storage and search for sensor data
(DIAMETERS/DIMENSIONS)
104>DIFS stands for__________
105>If we can partition aggregated data in a meaningful way, then we can distribute that data over
several nodes in the network and thus lessen the load on nodes near the hierarchy root. A system
that has developed this approach is__________ (DIPS/DIFS)
106>__________uses a modified GHT to find an index node (DIPS/DIFS)
107>The idea of storing information locally is at the heart of the__________ approach to storing
data in a sensor network (fractional cascading/locality preserving hashing)
108>The key idea of the_________ approach is to store at each sensor information about data
available elsewhere in the network ,but in such a way that a sensor knows only a fraction of the
information from distant parts of the network (fractional cascading/locality preserving hashing)
109>Fractional cascading accomplishes following goals simultaneously
a; the total amount of information duplication across all sensors is kept small because of the
geometric decrease with distance
b; the communication costs required to build this index and its update cost remain reasonable ,as on
a the average information travels only short distances
c; neighboring sensors have highly correlated world views ,this allows for smooth information
gradients and enables local search algorithms to work well
Ans; __________ (a/b/c/all)
110>DIM stands for__________
111>__________approach is developed in the DIM system (fractional cascading/locality preserving
hashing)
112>In__________ approach ,we map the attribute space to the plane so that nearby locations in
attribute space correspond to nearby locations in the plane (fractional cascading/locality preserving
hashing)
113>The key idea of __________is a clever construction of a locality preserving mapping between
the multidimensional attribute space and the spatial domain of sensors (DIM/DIFS)
114>_____databases has to store static information while_____ databases must deal with
continuous data acquisition and allow the temporal aspects of the data to be used in queries
(traditional/sensor network)
115>The sensor data acquired by a single node over time can be processed and summarized directly
on that node ,with no additional communication costs (true/false)___________
116>One of disadvantage of sensor network is that overall node storage is very limited
(true/false)__________
117>The__________ system computes multi-resolution summaries of data
(DIAMETERS/DIMENMSIONS)
118>__________is a monotonically decreasing function specifying acceptable query response
accuracy as a function of data age (mining function/aging function)
119>KDS stands fo___________120>wrt indexing motion data, in __________setting ,the
correctness of the index is certified by certain atomic predicates called certificates ,on the
parameters defining the index (KDC/KDS)
121>__________approach incrementally tracks the index structure as objects move and can be
used to answer queries about the current state of the world (KDC/KDS)
122>Following are general approaches to indexing motion data
a; using time oblivious approach
b; using KDS approach
Ans; __________ (a/b/both)
ANSWERS
1>all
2>T
3>centralized
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4>schema
5>DDL
6>Data Definition Language
7>row, column
8>DDL
9>metadata
10>storage & buffer manager
11>transaction
12>transaction manager
13>SQL
14>query processor, execution engine
15>T
16>distributed
17>distributed
18>node, edge
19>peer to peer
20>P2P
21>continuous
22>time-stamped
23>communication costs, energy landscape
24>both
25>both
26>all
27>all
28>all
29>data streams
30>P2P
31>T
32>high
33>duration, sampling period
34>continuous, snapshot, historical
35>all
36>T,T
37>cougar
38>both
39>ADT
40>ADT
41>physical
42>Short Time Fourier Transform
43>both
44>virtual
45>virtual, base
46>distributed
47>either
48>Gaussian ADT
49>GADT
50>diff
51>T
52>centralized
53>all
54>in-network storage
55>in-network storage
56>all
57>all
58>1-f 2-a 3-b 4-c 5-d 6-e
59>total usage, hot spot usage
60>both
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61>all
62>1-d 2-c 3-e 4-b 5-f 6-a
63>both
64>server
65>both
66>both
67>TinyDB
68>all
69>both
70>median, histogram
71>max, min, count & sum; average
72>median, histogram
73>inversely
74>epoch
75>static
76>node, edge
77>NP
78>server
79>Data Centric Storage
80>DCS
81>T
82>rendezvous
83>Geographic Hast Table
84>GHT
85>GHT
86>DCS
87>range
88>range
89>T
90>GHT
91>both
92>both
93>more
94>canonical subsets
95>internal
96>T
97>orthogonal range
98>both
99>all
100>k-d tree
101>T
102>both
103>DIMENSIONS
104>Distributed Index for Features in Sensor network
105>DIFS
106>DIFS
107>fractional cascading
108>fractional cascading
109>all
110>Distributed Index for Multi-dimensional data
111>locally preserving hash functions
112>locally preserving hash functions
113>DIM
114>traditional, sensor network
115>T
116>T
117>DIMENSIONS
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118>aging function
119>Kinetic Data Structure
120>KDS
121>KDS
122>both
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WIRELESS SENSOR NETWORKS
36
CHAPTER 7: SENSOR NETWORK PLATFORMS AND
TOOLS
1>Following are different types of programming for sensor networks
a: those carried out by end users
b: those performed by application developers
Ans: __________ (a/b/both)
2>_____may view a sensor network as a pool of data and interact with the network via queries.On
the other hand, _____must provide users of a sensor network with the capabilities of data
acquisition, processing and storage (end user/application developer)
3>CSIP stands for__________
4>Following are different types of node centric programming interfaces
a: imperative language, nesC
b: dataflow style language, TinyGals
Ans: __________ (a/b/both)
5>Following are examples of node level simulator
a: ns-2
b: TOSSIM
Ans: __________ (a/b/both)
6>___________centric programming gives programmers platform support for thinking in high level
abstraction (node/state)
7>Sensor node hardware can be grouped into following categories
a: augmented general purpose computers
b: dedicated embedded sensor nodes
c: system-on-chip (SoC) nodes
Ans: ___________ (a/b/c/all)
8>Match the following
augmented
general
purpose
computers:
smart dust, BWRC picoradio node and PASTA node
dedicated
embedded
sensor nodes:
Berkeley mote family, UCLA Medusa family, Ember nodes and MIT
microAMP
SoC nodes: low power PCs, embedded PCs, custom designed PC and various
PDA___________
9>COTS stands for
10>Compared with dedicated sensor nodes, PC like platforms are___________power hungry
(less/more)
11>Which sensor node hardware has high processing capability
a: augmented general purpose computers
b: dedicated embedded sensor nodes
c: SoC nodes
Ans: ___________ (a/b/c)
12>Which platform typically use COTS chip sets with emphasis on small from factor, low power
processing and communication, and simple sensor interfaces
a: augmented general purpose computers
b: dedicated embedded sensor nodes
c: SoC nodes
Ans: ___________ (a/b/c)
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13>Berkeley motes has gained wide popularity in the sensor network research community because
of
a: small form factor
b: open source software development
c: commercial availability
Ans: __________ (a/b/c/all)
14>Figure7.1___________
15>In MICA mote , the main micro-controller named___________ takes care of regular processing
(intel/Atmel ATmega103L)
16>In MICA mote, the ATmega103L MCU has integrated____ kB flash memory and ___kB of data
memory (4/64/512)___
17>The RF communication on MICA motes uses the TR=____chip set operating at ____MHz band
(916/1000/1024)
18>MICA motes implement a____ kbps transmission rate (40/60/80)_______
19>MICA mote has maximum transmission range of about ___________feet in open space
(100/200/300)
20>MICA motes support a ____pin I/O extension connector (50/51/52)_______
21>figure7.3___________
22>Radio transmission bear the maximum power consumption (true/false)___________
23>Stand alone embedded systems do not scale up for the programming of sensor networks for
following reasons
a: sensor networks are large scale distributed systems, where global properties are derivable from
program execution in a massive number of distributed nodes
b: sensor network should be able to respond o multiple concurrent stimuli at the speed of changes
of the physical phenomena of interest
Ans: ___________ (a/b/both)
24>___________implies a conceptual model for programmers, with associated techniques for
problem decomposition for the software designers (design platform/design methodologies)
25>_____supports a______ by providing design time language constructs and restrictions, and run
time execution services (design platform/design methodologies)
26>Most design methodologies for sensor network software are___________ centric, where
programmers think in terms of how a node should behave in the environment (state/node)
27>Following are representative examples of node-level programming tools___________
(TinyOS/TinyGALS)
28>___________aims at supporting sensor network applications on resource constrained hardware
platforms such as the Berkeley motes (TinyOS/TinyGALS)
29>___________is a virtual machine for the Berkeley motes (MICA/mate)
30>Features of TinyOS
a: have no file system
b: supports only static memory allocation: implements a simple task model
d: provides minimal device & networking abstractions
e: takes a language based application development approaches
Ans: ___________ (a/b/c/d/e/all)
31>TinyOS organizes components into layers, the_____ a layer is , the closer it is to the hardware;
the______ a layer is, the closer it is to the application (lower/higher)
32>In TinyOS, tasks are non-preemptive (true/false)___________
33>The execution of an interrupt handler is called___________ (event context/event scheduler)
34>___________is an extension of C to support and reflect the design of TinyOS v1.0 and above
(TinyGALS/nesC)
35>___________provides a set of language constructs and restrictions to implement TinyOS
components and applications (nesC/ns2)
36>Interfaces of a nesC component are classified as___________ interfaces (provides/uses)
37>_____interface is a set of method calls exposed to the upper layers while a______ interface is a
set of method calls hiding the lower layer components (provides/uses)
38>In nesC component, _____call is a method call from a lower layer component to a higher layer
component while a______ call is a method call from a higher layer component to a lower layer
component (command/event)
VTU
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MULTIPLE CHOICE QUESTIONS WITH ANSWERS ON WIRELESS SENSOR NETWORKS
MULTIPLE CHOICE QUESTIONS WITH ANSWERS ON WIRELESS SENSOR NETWORKS
MULTIPLE CHOICE QUESTIONS WITH ANSWERS ON WIRELESS SENSOR NETWORKS
MULTIPLE CHOICE QUESTIONS WITH ANSWERS ON WIRELESS SENSOR NETWORKS
MULTIPLE CHOICE QUESTIONS WITH ANSWERS ON WIRELESS SENSOR NETWORKS
MULTIPLE CHOICE QUESTIONS WITH ANSWERS ON WIRELESS SENSOR NETWORKS
MULTIPLE CHOICE QUESTIONS WITH ANSWERS ON WIRELESS SENSOR NETWORKS

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MULTIPLE CHOICE QUESTIONS WITH ANSWERS ON WIRELESS SENSOR NETWORKS

  • 1.
  • 2. WIRELESS SENSOR NETWORKS 1 CHAPTER 1: INTRODUCTION 1>MEMS stands for__________ 2>A sensor network is subject to a unique set of resource constraints such as a: finite on-board battery power b: limited network communication bandwidth Ans: ________ (a/b/both) 3>In a typical sensor network, each sensor node operates unethered and has a microprocessor and a small amount of memory for signal processing and task scheduling (true/false)__________ 4>Each node is equipped with one or more sensing devices such as acoustic microphone arrays, video or still cameras, infrared, seismic or magnetic sensors (true/false)__________ 5>Information collected by and transmitted on a sensor network describes conditions of physical environments and requires advanced query interfaces and search engines to effectively support user-level functions (true/false)__________ 6>___________routes user queries or commands to appropriate nodes in a sensor network (bridge/gateway) 7>Communicating 1 bit over the wireless medium at short ranges consumes ___________energy than processing that bit (less/more) 8>For the Sensoria sensors and Berkeley motes, the ratio of energy consumption for communication and computation is in the range of _____to______ (100/1000/10000) 9>A sensor network is designed to collect information from a___________ environment (logical/physical) 10>Table1.1___________ 11>It is more appropriate to address nodes in a sensor network by_____ than by______ (IP address/physical properties) 12>Mobility and instability in wireless links prevent the use of many existing edge network gateway protocols for internetworking IP and sensor networks (true/false)__________ 13>The challenges we face in designing sensor network systems and applications include a: limited hardware b: limited support for networking c: limited support for software development Ans: ___________ (a/b/c/all) 14>Match the following Limited hardware: the tasks are typically real-time and massively distributed, involve dynamic collaboration among nodes, and must handle multiple competing events Limited support for networking: each node has limited processing, storage and communication capabilities, and limited energy supply and bandwidth Limited support for software development: the network is peer-to-peer , with a mesh topology and dynamic, mobile and unreliable connectivity 15>Following are advantages of sensor network a: energy advantage b: detection advantage Ans: ___________ (a/b/both) 16>Dense networks of distributed communicating sensors can improve SNR by reducing average distances from sensor to source of signal or target (true/false)__________ 17>The greatest advantage of networked sensing are in improved___________ (robustness/scalability/both) 18>A___________ sensing system is inherently more robust against individual sensor node or link failures, because of redundancy in the network (centralized/decentralized) 19>Because of the unique attenuation characteristics of RF signals, _____network provides a significant energy saving over ______network for the same distance (single hop/multi hop) VTU N O TESBYSR I
  • 3. WIRELESS SENSOR NETWORKS 2 20>The RF attenuation model near the ground is given by a: Preceive ¤ Psend/r b: Psend ¤ Preceive/p Ans: ___________ (a/b/either) 21>In above expression, alpha is typically in the range of__to___ (2/3/4/5) 22>The power advantage of an N-hop transmission versus a single hop transmission over the same distance Nr is a: nrf=N(alpha-1) b: nrf=N(alpha+1) Ans: ___________ (a/b/both) 23>In above expression, ___________N gives a larger power saving due to the consideration of RF energy alone (smaller/larger) 24>Using more nodes increases a: the cost b: the power consumption of components Ans: ___________ (a/b/both) 25>Each sensor has a finite sensing range, determined by the___________ floor of the sensor (ground/noise) 26>Densor sensor field improves the odds of detecting a signal source within the range (true/false)___________ 27>Once a signal source is inside the sensing range of a sensor, further increasing the sensor density ___________the average distance from a sensor to the signal source, hence improving the SNR (decreases/increases) 28>wrt the acoustic sensing case in a two-dimensional plane, the acoustic power received at a distance r is given by a: Psend ¤ Precieve/r*r b: Preceive ¤ Psource/r*r Ans: ___________ (a/b/either) 29>Wrt acoustic sensing case in a two-dimensional plane, the SNR is given by a: SNR=10logPsource+10logPnoise+20logr b: SNR=10logPsource-10logPnoise-20logr Ans: ___________ (a/b/either) 30>The SNR advantage of the denser sensor network is given by a: nsnr=20logk b: nsnr=10logk Ans: ___________ (a/b/either) 31>An increase in sensor density by a factor of k improves the SNR at a sensor by ___________db (10logk/20logk) 32>A sensor network is designed to perform a set of high level information processing tasks such as a: detection b: tracking c: classification Ans: ___________ (a/b/c/all) 33>Following are sample commercial and military applications include a: environmental monitoring b: industrial sensing and diagnostics c: infrastructure protection d: battlefield awareness e: context aware computing Ans: ___________ (a/b/c/d/e/all) 34>Match the following environmental monitoring : intelligent home, responsive environment Industrial sensing and diagnostics : multi-target tracking Infrastructure protection : power grids, water distribution Battlefield awareness : traffic, habitat, security Context aware computing : appliances, factory, supply chains VTU N O TESBYSR I
  • 4. WIRELESS SENSOR NETWORKS 3 35>If every sensor has some data that it needs to send to another node in a network, then per node throughput scales as___________{sqrt(N) or 1/sqrt (N)} 36>As the number of nodes___________, every node spends almost all of its time forwarding packets of other nodes (decreases/increases) 37>CSIP stands for___________ 38>___________refers to signal and information processing problems dominated by the issue of selecting embedded sensors to participate in an information processing task (CSIP/CCIP) 39>___________is an interdisciplinary research area that draws on contributions from signal processing, networking and protocols, databases and information management, distributed algorithms, and embedded systems and architecture (wireless networks/sensor networks) 40>Match the following sensor: routing of data based on geographical attributes such as locations or regions sensor node: the process of determining a network path from a packet source node to its destination network topology: approaches that name, route or access a piece of data via properties that are external to a communication network routing: a transducer that converts a physical phenomenon that may be further manipulated by other apparatus data centric: a basic unit with on-board sensors, processor, memory, wireless modem and power supply geographic routing: a connectivity graph where nodes are sensor nodes and edges are communication links 41>Match the following In-network: the process of discovering the existence of a physical phenomenon Collaborative processing: either high-level system tasks which may include sensing, communication, processing and resource allocation or application tasks which may include detection, classification , localization or tracking State: a condition of the information caused by noise in sensor measurements or lack of knowledge in models Uncertainty: a snapshot about a physical environment or a snapshot of the system itself Task: sensors cooperatively processing data from multiple sources in order to serve a high level task Detection: a style of processing in which the data is processed and combined near where the data is generated 42>Match the following Classification: the assignment of sensors to a particular task and the control of sensor state for accomplishing the task Localization & tracking: services such as time synchronization and node localization that enable applications to discover properties of a node and the nodes to organize themselves into a useful network Value of information: resources include sensors, communication links, processors , on- board memory and node energy reserves Sensor tasking: the estimation of the state of a physical entity such asa physical phenomenon or a sensor node from a set of measurements Resource: a mapping of data to a scalar number, in the context of the overall system task and knowledge Node services: the assignment of class labels to a set of physical phenomena being observed VTU N O TESBYSR I
  • 5. WIRELESS SENSOR NETWORKS 4 43>Match the following Data storage: the abstract characterization of system properties Embedded OS: a measurable quantity that describes how well the system is performing on some absolute scale System performance goal: sensor information is stored, indexed and accessed by applications Evaluation metric: the run-time system support for sensor network applications ANSWERS 1>Micro Electro Mechanical System 2>both 3>T 4>T 5>T 6>gateway 7>more 8>1000 to 100000 9>physical 10> 11>physical properties, IP address 12>T 13>all 14>1-b 2-c 3-a 15>both. 16>T 17>Both 18>decentralised 19>multihop, single hop 20>a 21>2-5 22>a 23>larger 24>both 25>noise 26>T 27>decreases 28>b 29>b 30>b 31>10logk 32>all 33>all 34>1-d 2-e 3-c 4-b 5-a 35>1/sqrt(N) 36>increases 37>Collaborative Signal & Information Processing 38>CSIP 39>sensor networks 40>1-d 2-e 3-f 4-b 5-a 6-c 41>1-f 2-e 3-d 4-c 5-b 6-a 42>1-f 2-d 3-e 4-a 5-c 6-b 43>1-c 2-d 3-a 4-b VTU N O TESBYSR I
  • 6. WIRELESS SENSOR NETWORKS 5 CHAPTER 2: CANONICAL PROBLEM – LOCALIZATION AND TRACKING 1>Localizing and tracking moving objects is an essential capability for a sensor network in many practical applications (true/false)__________ 2>A central problem for CSIP is to dynamically define and form sensor groups based on__________ (task requirements/resource availability/both) 3>A sensor network can be defined as an abstract tuple G=<V, E, Pv, Pe> where __specifies nodes, ___specifies link connectivity, __is a set of functions that characterizes the properties of each node and ___specifies properties of each link 4>DOA stands for__________ 5>__________is a distributed physical quantity such as temperature, pressure or optical flow across a region of space (area/field) 6>A tracking task can be formulated as a constrained optimization problem <G, T, W, Q, J, C> where__is the sensor network , __is a set of targets, __is a signal model for how target signals propagate and attenuate in the physical medium, __denotes a set of user queries, __specifies an objective function defined by task requirements and__ specifies a set of constraints 7>In wireless sensor networks, some of the information defining the objective function and constraints is available only at___________ (compile time/run time) 8>The position estimation may be accomplished by a: triangulation computation b: least square computation Ans: ___________ (a/b/either) 9>Bayesian estimation can be used for position estimation (true/false)___________ 10>When the two targets move close to a target track, ___________problem has to be addressed (data relationship/data association) 11>Tracking scenario raises following fundamental information processing issues a: in collaborative processing, the issue of target detection, localization, tracking and sensor tasking and control b: in networking, the issues of data naming , aggregation and routing c: in databases, the issues of data abstraction and query optimization d: in human-computer interface, the issues of data browsing , search and visualization e: in infrastructure services, the issues of network initialization and discovery, time ad location services, fault management and security Ans: ___________ (a/b/c/d/e/all) 12>Give an expression relating zi, ai, x, wi , and Ans: __________ 13>To uniquely determine the location on a two-dimensional plane, one needs alleast ___________independent distance measurements (two/three) 14>TDOA stands for___________ 15>___________determines the significance of the contribution of each sensor a: geometry of the sensor placement b: distance to the signal source Ans: __ (a/b) 16>The goal of localization or tracking is to obtain a good estimate of the target state from the measurement history (true/false)__________ 17>We refer to the___________ distribution as the current belief (priori/posterior) 18>The relationship between the posterior distribution p (x|z), the priori distribution p (x) , and the likelihood function p (z|x) is given by Bayes Theorem a: p (x|z)=p (z|x)p (x)/p (x) b: p (x|z)=p (z|x)p (x)/p (z) Ans: ___________ (a/b/either) 19>In above expression, ____is the marginal distribution, which is also called the normalizig constant{p (x) or p (z)}_______ VTU N O TESBYSR I
  • 7. WIRELESS SENSOR NETWORKS 6 20>MMSE stands for___________ 21>A commonly used estimator in the standard estimation theory is the___________ (MEMS/MMSE) 22>The___________ algorithm is inefficient in utilizing the communication resources (centralized/distributed) 23>From the processing point of view, the complexity of the___________ algorithm scales linearly with K, and hence is prohibitive for large networks (centralized/distributed) 24>In___________ filter, the belief distributions and error models are Gaussians and the system dynamics model is linear (kalman/particle) 25>In following ways we can approximate an arbitrary belief state regarding the targets a: we can approximate the belief by a family of distributions b: we can approximate the belief by weighted point samples Ans: ___________ (a/b/both) 26>PMF stands for___________ 27>We can approximate the belief by weighted point samples .Following are examples of this approximation a: discretizing the subset of S by a grid b: the particle filter approximation of distribution c: the kalman filter approximation of distribution Ans: __________ (a/b/c/all) 28>A variant of belief approximation by weighted point samples is to partition S and assign a probability value to each region which is called ___________type approach (histogram/heuristic) 29>The belief approximation by weighted point samples is called__________ (parametric/nonparametric) 30>The belief approximation by a family of distribution is called___________ (parametric/nonparametric) 31>If we must pass the belief to a remote sensor, we are faced with the following trade off. Representing the true belief by a______ approximation with relatively few parameters will result in a poor approximation of the belief state but with the benefit that fewer bits need to be transmitted. On the other hand, representing the true belief by_____ approximation will result in a more accurate approximation of the belief at the cost of more transmitted bits (parametric/nonparametric) 32>Gaussian approximation is example of___________ approximation (parametric/nonparametric) 33>In the___________ design, the robustness of the tracker may suffer from occasional leader node attrition (moving leader/single moving) 34>The___________ design can be used for tracking multiple targets in a sensor field, with one leader-node tracking each target (moving leader/single moving) 35>The belief state can be stored in a distributed fashion across a section of sensor nodes. This is attractive from the___________ point of view (robustness/security) 36>___________is key problem in designing distributed CSIP applications (information representation/storage/ access/all) 37>While defining a unifying architecture for sensor networks is still an open problem, a key element of such an architecture is the principled interaction between the______ &_____layers (application/transport/network) 38>Tracking multiple interacting targets distributed over a geographical region is significantly more challenging for following reasons a: curse of dimensionality b: mapping to distributed platforms Ans: ___________ (a/b/both) 39>The presence and interaction of multiple phenomena cause the dimension of the underlying state spaces to ___________ (decrease/increase) 40>To ensure the ___________of the system, the communication and computation should be localized to relevant sensors only (responsiveness/scalability/both) 41>The key idea in the state-space factorization is to decouple information in a state space into___________ information (location/identity/both) 42>The tracking problem can be solved separately by______ which requires frequent local communication, and by_____ which requires less frequent, longer range communication (location estimation/identity management) VTU N O TESBYSR I
  • 8. WIRELESS SENSOR NETWORKS 7 43>Following approaches can be used for tracking multiple objects a: state space decomposition b: data association Ans: ___________ (a/b/both) 44>In___________ approach, the target location and identity information are coupled and processed in the same space (state space decomposition/ data association) 45>To address the data association problem, following methods can be used________ (MHT/JPDA/both) 46>MHT stands for___________ 47>JPDA stands for___________ 48>_____forms and maintains multiple association hypotheses. On the other hand, ______evaluates the association probabilities and combines them to compute the state estimate (MHT/JPDA) 49>The distributed ___________filter is a global method, requiring each sensor node to communicate its measurement to a central node, where estimation and tracking are carried out (kalman/particle) 50>In___________ filter method, sensing is distributed while tracking is centralized (kalman/particle) 51>Replicated information is one of the serious problem in distributed tracking, whether the tracking is about a single target or multiple targets (true/false)___________ 52>Following are sources of information double counting a: due to loopy propagation of evidence in a network b: due to multiple sensor nodes observing a single target and reporting multiple detections Ans: ___________ (a/b/both) 53>Following are common types of sensors for tracking a: acoustic amplitude sensors b: DOA sensors Ans: ___________ (a/b/both) 54>DOA stands for___________ 55>___________sensor node measures sound amplitude at the microphone and estimates the distance to the target based on the physics of sound attenuation (acoustic DOA/acoustic amplitude) 56>___________sensor is a small microphone array. Using beam forming techniques, it can determine the direction from which the sound comes, that is, the bearing of the target (acoustic DOA/acoustic amplitude) 57>______sensors estimate distance based on received signal strength or TOA, while_____ sensors estimate signal bearing based on TDOA (range/DOA) 58>for sensor network applications, a sensor may be characterized by properties such as cost, size, sensitivity, resolution, response time, energy usage and ease of calibration & installation (true/false)___________ 59>RMS stands for___________ 60>Assuming that the sound source is a point source and sound propagation is lossless and isotropic, RMS amplitude measurement z is related to the sound position x by Ans: ___________ 61>___________sensing provides a range estimate (frequency/amplitude) 62>___________algorithms are commonly used in radar, speech processing and wireless communication to enhance signals received at an array of sensors (beam forming/bayesian state) 63>The relative time delay between two sensors with a spacing d can be expressed as a function of the bearing angle given by a: tm= (d/c)sin b: tm= (c/d)sin Ans: ___________ 64>Following methods are examples of DOA estimation algorithms___________ (least squares/maximum likelihood/both) 65>___________method solves for target bearing and location by estimating first the time difference of arrival at a set of sensors and then the source location (least squares/maximum likelihood) VTU N O TESBYSR I
  • 9. WIRELESS SENSOR NETWORKS 8 66>___________method typically converts a set of signals from time domain to frequency domain and then performs a possibly multidimensional search to find the peak in the correlation spectra (least squares/maximum likelihood) 67>_____method can be applied to both near and far field problems whereas______ method is particularly useful for near field problems in which the target is relatively close to the sensors compared with the sensor spacing (least squares/maximum likelihood) 68>In DOA sensor, The likelihood function is given by Ans: ___________ 69>The DOA estimate is_____ reliable in the medium distance range and is______ reliable when the sound source is too close or far away from the microphone array (less/more) 70>wrt DOA sensor, in the_____ field, the planar wave assumption is violated. In the______ field, the SNR is low, and he DOA estimation may be strongly influenced by noise and fail to converge to the correct angle (near/far) 71>Following are some of the commonly used measures of performance a: delectability b: accuracy c: scalability d: survivability e: resource usage Ans: ___________ (a/b/c/d/e/all) 72>Match the following Delectability: what is the amount of resources that each task consumes Accuracy: how does the system perform in the presence of node or link failures as well as malicious attacks Scalability: this may be measured by sensor coverage, detection resolution, dynamic range or response latency Survivability: this is typically characterized in terms of tracking errors or detection and classification errors Resource usage: how does a specific property of the system vary as the size of the network, the number of physical stimuli or the number of active queries increases 73>For___________ problems, performance is typically measured by false alarms and misses (detection/classification/tracking/all) 74>For___________ problem, performance goals and measures can be stated in terms of target and system parameters (detection/classification/tracking/all) 75>_____occurs when the outcome is incorrectly predicted as a positive when it is in fact a negative.______ is when the outcome is incorrectly labeled as a negative when in fact it is a positive (false negative/false positive) 76>Match the following Source SNR : percentage of runs of a full scenario where continuity of vehicle identity is not correctly maintained Obstacle density : the number of hours of target tracking versus the total number of node hours in fully awake mode for the entire network Network sleep efficiency : this may be measured by the probability of LOS obstruction for a randomly placed target-sensor pair Percentage of track loss : this is measured as the SNR at a reference distance from the signal source ___________ 77>For an acoustic source, ___________is defined as the log ratio of SPL of source at the reference distance over SPL of background noise (source SNR/receiver SNR) VTU N O TESBYSR I
  • 10. WIRELESS SENSOR NETWORKS 9 78>Match the following Detection of robustness : active lifetime, sleep lifetime, sleep efficiency Detection spatial resolution : link capacity Detection latency : %node loss Classification robustness : sensor coverage area, target maneuvers, obstacle density Track continuity : source SNR System survivability : link delay Cross-node DOA estimation : inter-target spacing Power efficiency : ANSWERS 1>T 2>both 3>V,E,Pv,Pe 4>Direction-Of-Arrival 5>field 6>G, T, W, Q, J, C 7>run time 8>both 9>T 10>data association 11>all 12>z = h(x , ) 13>3 14>Time Difference Of Arrival 15>both 16>T 17>posterior 18>b 19>p(z) 20>Minimum Mean Squared Error 21>MMSE 22>centralized 23>centralized 24>Kalman 25>both 26>Probability Mass Function 27>a, b 28>histogram 29>non parametric 30>parametric 31>parametric, non-parametric 32>parametric 33>single moving 34>moving leader 35>robustness 36>all 37>application, networking 38>both 39>increase 40>both 41>both 42>location estimation, identity management 43>both 44>data association 45>both VTU N O TESBYSR I
  • 11. WIRELESS SENSOR NETWORKS 10 46>Multiple Hypothesis Tracking 47>Joint Probabistic Data Association 48>MHT,JPDA 49>Kalman 50>kalman 51>T 52>both 53>both 54>Direction of arrival 55>acoustic amplitude 56>acoustic DOA 57>range, DOA 58>T 59>Root Mean Square 60>z=a/x- + w 61>amplitude 62>beam forming 63>a 64>both 65>least square 66>ML(maximum likelihood) 67>ML 68> 69>more, less 70>near, far 71>all 72>1-c 2-d 3-c 4-b 5-a 73>dtection, classification 74>tracking 75>false positive, false negative 76>1-d 2-c 3-b 4-a 77>source SNR 78>1-e 2-g 3-b 4-e 5-d 6-c 7-b 8-a VTU N O TESBYSR I
  • 12. WIRELESS SENSOR NETWORKS 11 CHAPTER 3: NETWORKING SENSORS 1>Networking allows geographical distribution of the sensor nodes and their placement close to signal sources (true/false)__________ 2>Radio communication is the most expensive operation a node performs in terms of energy usage, and thus it must be used sparingly and only as dictated by the task requirements (true/false)__________ 3>Sensor networks are typically deployed in an adhoc manner (true/false)__________ 4>Wireless communication between nodes utilizes radio links (true/false)__________ 5>Within the coverage range, communication is by__________ (multicast/broadcast) 6>UDG stands for___________ 7>Nodes operate unethered and have limited power resources (true/false)___________ 8>For communication, the main consideration is that communication paths consists of many short hops can be___________ energy efficient than paths using a few long hops (less/more) 9>Networking involves multiple layers in the protocol stack (true/false)___________ 10>___________sub-layer manages access to the physical network medium, and its fundamental goal is to reduce or avoid packet collisions in the medium (MAC/LLC) 11>Following characteristics of wireless sensor networks point to the need for a specialized MAC protocol a: the issues of fairness of the node level are much less important than overall application performance b: most sensor nodes are idle much of the time c: In-network processing can greatly improve bandwidth utilization d: the assumed lack of mobility and therefore the relatively fixed neighborhood of each node can be exploited in medium access protocol design e: issues of energy efficiency, scalability and robustness remain paramount Ans: ___________ (a/b/c/d/e/all) 12>Following MAC protocols have been developed for wireless voice and data communication networks a: TDMA b: FDMA c: CDMA d: CSMA e: WLAN Ans: __________ (a/b/c/d/e/all) 13>The main goal of the ___________is to reduce energy waste caused by idle listening, collisions, overhearing and control overhead (S-MAC protocol/IEEE802.15.4 standard) 14>The S-MAC protocol includes following major components a: periodic listen and sleep b: collision avoidance c: overheating avoidance d: message passing Ans: ___________ (a/b/c/d/all) 15>In the S-MAC protocol, ___________is designed to reduce energy consumption during the long idle time when no sensing events happen, by turning off the radio periodically (message passing/periodic listen and sleep) 16>DCF stands for__________ 17>___________in S-MAC is similar to the DCF for IEEE802.11 adhoc mode using an RTS/CTS exchange (overhearing avoidance/collision avoidance) 18>___________defines both the physical and MAC layer protocols for most remote monitoring and control as well as sensor network applications (S-MAC protocol/IEEE802.15.4 standard) 19>___________is an industry consortium with the goal of promoting the IEEE802.15.4 standard (bluetooth/zigbee) VTU N O TESBYSR I
  • 13. WIRELESS SENSOR NETWORKS 12 20>Following are features of Zigbee a: it is an industry consortium with the goal of promoting the IEEE802.15.4 standard b: it ensures interoperability by defining higher network layers and application interfaces c: it is optimized for low data throughput up to 115.2 kbps, with simple or no Qos support___________ 21>Unlike_____, ______achieves its power efficiency from both the physical and MAC layers (S- MAC protocol/IEEE802.15.4 standard) 22>Following are essential characteristics of current sensor network a: the nodes have only modest processing power and memory b: network links and nodes can come and go Ans: ___________ (a/b/both) 23>___________type protocols only broadcast topology changes to neighbors, but because of that they converge slowly (link state/distance vector) 24>Proactive protocols of the ___________type need to broadcast to the entire network topology changes when these are locally detected (LS/DV) 25>Following strategies have been suggested to mitigate the demands of the dynamic changes on the network a: the frequency of topology updates to distant parts of the network can be reduced , as in fisheye state routing b: reactive protocols can be used instead, constructing paths on demand only. Eg: DSR, AODV Ans: ___________ (a/b/both) 26>DSR stands for___________ 27>AODV stands for___________ 28>Following are examples of reactive protocol___________ (DSR/AODV) 29>information providers and information seekers need to be matched usig data attributes and not hard network addresses (true/false)___________ 30>Examples of data attributes may include a: node's location b: node's type of sensors c: certain range of values in a certain type of sensed data Ans: ___________ (a/b/c/all) 31>The network must be both a database that can be queried about the world state, which is called_____ operation and an entity that can actively initiate an action when something of interest is sensed which is called______ (push/pull) 32>Aim of the routing protocols is to deliver packets to nodes or areas of the network specified by their geographic location (true/false)___________ 33>It may be more economical to use a ___________transmission radius for nodes in areas of high node density (larger/smaller) 34>It may be more economical to use a smaller transmission radius for nodes in areas of high node density, w/o sacrificing adequate network connectivity. This is the issue of___________ (topology control/traffic control) 35>In___________ routing, among the neighbors y of x closer to d than x, pick the one closest to d (greedy distance/compass) 36>In ___________ routing, among the neighbors y of x that make an angle dxy< , we pick one that minimizes the angle dxy (greedy distance/compass) 37>If G contains the Delaunay triangulation of V, then the ___________protocol always works (greedy distance/compass/both ) 38>___________routing has guaranteed delivery when G Is the Delaunay triangulation of V (greedy distance/compass/both) 39>___________routing states that "start in the face of G just beyond s along sd and walk around that face. Stop if d is reached or if the segment sd is about to be crossed. In the latter case, cross over into the next face of G along sd and repeat the process" (greedy distance/compass /convex perimeter) 40>OFR stands for ___________ 41>In___________ protocol, after we go around a face F, we continue into a new face F' not from the farthest with F, but instead from the vertex of F closest to d (OFR/perimeter) 42>OAFR stands for___________ VTU N O TESBYSR I
  • 14. WIRELESS SENSOR NETWORKS 13 43>We can start with a small guess and double it every time we fail to reach d with our current guess, until d is reached. This defines adaptive versions of the perimeter protocol called___________ (OAFR/adaptive perimeter) 44>We say that a sub-graph H of G is a ___________for G if H is a graph on the same vertex set as G, is missing some of the edges of G, yet there is a constant 'a', a>=1, such that for any pair of vertices u and v the length of the shortest path between u and v in H is at most 'a' times that of the length of the shortest path between u and v in G. The constant 'a' is called the__________ (stretch factor/spanner) 45>A number of the standard geometric graph constructions for a set of points V can be used to define planarizations of the graph G. The most common such constructions are ___________ (Gabriel/RNG/both) 46>RNG stands for___________ 47>In___________, the edges xy is introduced if the lune is free of other nodes (Gabriel/RNG) 48>In___________, the edges xy is introduced if the circle of diameter xy is free of other nodes_ (Gabriel/RNG) 49>_____is a super-graph of the_______ (Gabriel/RNG/both 50>The Delaunay triangulation is known to be___________ of the complete Euclidean graph on V (planar/spanner/both) 51>RDG stands for___________ 52>LDel Stands for___________ 53>While ___________protocols are extremely simple, they can get stuck in local minima. In contrast, ______protocols can provide guaranteed delivery, but require both preprocessing and a significantly more complex routing algorithm (greedy distance/perimeter) 54>GPSR stands for___________ 55>GPSR protocol is a mixture of___________ (greedy distance/perimeter/both) 56>Normally GPSR defaults to ______routing. When it gets stuck, then the_____ protocol is invoked but only until a node is encountered that is closer to the destination (greedy distance/perimeter) 57>TBF stands for___________ 58>Another form of geographical routing, applicable in a number of dense node coverage settings, is to specify an ideal curve that a packet should follow, as opposed to the packet's final destination. This is called___________ (OFR/TBF) 59>___________routing is a method for bringing together information seekers and information providers in a sensor network (greedy distance/rumour) 60>Following aspects of the energy cost in a sensor network make it challenging to reason about optimizing energy a: multi-hop communication can be more efficient than direct transmission b: when a node transmits, all other nodes within range can hear Ans: ___________ (a/b/both) 61>Multi-hop communication can be_____ efficient than direct transmission (less/more) 62>The nodes communicate using radio links, where the signal amplitude drops with distance according to a power law of the form_____ where typically 2<=a<=5{ O (ra ) or O (1/ ra )} ______ 63>In ___________problem, our goal is to find a schedule of broadcasts and retransmissions that allows the message to reach all nodes while minimizing the total energy expended (minimum energy broadcast/maximum energy multicast) 64>MST stands for___________ 65>The broadcast nature of radio transmissions changes the minimum energy broadcast problem, as node u transmitting to reach another node v is also reaches all nodes closer than v at no extra cost. This is called__________ (wireless broadcast advantage/wireless multicast advantage) 66>The minimum energy broadcast problem for both general and geometric graphs is_______ complete (PN/NP) 67>In the worst case , the MST based algorithm gives a broadcast tree whose total energy usage is between ___&___times the minimum needed (6/12/18) 68>The key idea that establishes the constant factor approximation is a proof that the minimum energy required for the broadcast problem can be bounded from below by a constant times the energy cost of the MST based broadcast tree (true/false)___________ VTU N O TESBYSR I
  • 15. WIRELESS SENSOR NETWORKS 14 69>BIP stands for___________ 70>The BIP works like MST algorithm of___________, adding nodes to the broadcast tree one at a time, starting with the source (kruskal/prim) 71>GEAR stands for ___________ 72>The goal of___________ is to efficiently route a message to a geographic region while at the same time performing load balancing on the nodes used and thus avoiding energy depletion (GEAR/GPSR) 73>The GEAR protocol operates in following phases a: deliver the packet to a node in the desired region b: distribute the packet within the region Ans: ___________ (a/b/both) 74>During the ___________ phase, GEAR behaves like a unicast protocol routing the message to the centroid d of the region R except that it considers the energy resources of each node as well (delivery/distribution) 75>LRTA stands for___________ 76>GEAR provides a__to__% increase in the number of packets transmitted before network partition, __% increase in the number of connected pairs of nodes after network partition, and the average increase in the path length taken by a packet due to load balancing was between__&__ (25/45/50/100) 77>The second phase of GEAR deals with packet distribution within the destination region R, once the packet has reached a node x in the region. One of the following strategies can be used here a: recursive geographic forwarding b: restricted flooding Ans: ___________ (a/b/both) 78>___________refers to a process of recursively partitioning the region R into quadrants and then forwarding the packet from x to the centroid of each quadrant (restricted flooding/recursive geographic forwarding) 79>___________refers to the initiating a broadcast flooding process from x that is clipped at the boundary of R (restricted flooding/recursive geographic forwarding) 80>While____________ has the "wireless multicast advantage", it may till prove wasteful when the region R is densely populated by nodes and the same packet reaches a node multiple times (restricted flooding/recursive geographic forwarding) 81>In directed diffusion, nodes requesting information are called___ while those generating information are called___. Records indicating a desire for certain type of information are called_____ (interests/sinks/sources) 82>wrt directed diffusion, ___________attribute field indicates the frequency with which the sink wishes to receive information about objects matching the other record attributes (duration/interval/timestamp) 83>wrt directed diffusion, the period of validity of an interest is encoded in its___________ attribute (duration/interval/timestamp) 84>In directed diffusion, ___________generate information request tasks or interests , that diffuse through the sensor network (sources/sinks) 85>An essential component of directed diffusion is the use of___________ associated with each interest cache entry, used to direct and control information flowback to the sink (gradient/gateway) 86>In directed diffusion, a gradient is typically derived from the frequency with which a ___________requests repeated data about an interest (source/sink) 87>In data____ type, all communications happened because of the sink's request while in data _______type, directed diffusion lets sensor nodes trigger event propagation when they detect something that they believe might be of interest to potential sinks (push/pull) 88>Directed diffusion provides a general-purpose communication mechanism for sensor networks (true/false)___________ 89>Directed diffusion is___________ centric in its network view and performs all routing decisions through local, neighbor-to-neighbor interactions (state/node) 90>Directed diffusion provide a___________ routing technique, discovering routes between information sources and sinks as needed (proactive/reactive) 91>Directed diffusion can effectively suppress duplicate events and perform in-network information aggregation (true/false)___________ VTU N O TESBYSR I
  • 16. WIRELESS SENSOR NETWORKS 15 92>There are may situations in which, because the amount of data to be exchanged is small, the quality of the paths does not matter so much. In such situations, ___________routing can be used (rumour/reactive) 93>In___________ routing, in order to get sources and sinks to meet each other, we must spread information from each regions of the sensor field, so that the two growing regions eventually intersect (rumour/reactive) 94>Related to rumour routing is the___________ query answering mechanism (ACQUIRE/ACCESS) 95>In rumor routing, ___________approach is most appropriate for situations when we need to process one-shot complex queries, whose answers depend on information obtained in several nodes of the network (ACQUIRE/ACCESS) 96>wrt rumour routing, the idea of the ___________system is to elect a leader node whose goal is to compute the answer to the query (ACQUIRE/ACCESS) 97>IDSQ stands for___________ 98>GHT stands for___________ 99>GHT is a robust protocol (true/false)___________ 100>One of the most elegant aspects of GHT is the way that it exploits features of the___________ routing protocol accomplish its goal (GEAR/GPSR) 101>A nice feature of the perimeter refresh protocol is that it helps to recover from node failures (true/false)__________ 102>In wireless sensor network, the issues of fail utilization of networking resources at the node level are__________ important than just accomplishing the overall goal(less/more) 103>What is important to the sensor network is the information the nodes contain, not the nodes themselves (true/false)__________ 104>In wireless sensor networks, nodes are ephemeral i.e. they can be destroyed, be asleep or die from malfunction or battery depletion (true/false)__________ 105>Preservation of energy is of paramount concern in wireless sensor network (true/false)__________ 106>Network for sensor networks is ____centric but not ______centric (node/data) 107>GHT uses a perimeter refresh protocol a: to accomplish replication of attribute-value pairs b: to ensure their consistent placement in the appropriate home node c: to recover from node or link failures Ans: ___________ (a/b/c/all) ANSWERS 1>T 2>T 3>T 4>T 5>broadcast 6>Unit Distance Graph 7>T 8>more 9>T 10>MAC 11>all 12>all 13>S-MAC 14>all 15>periodic listen & sleep 16>Distributed Coordinate Function 17>collision avoidance 18>IEEE 802.15.4 19>ZigBee 20>all 21>S-MAC, 802.15.4 22>both VTU N O TESBYSR I
  • 17. WIRELESS SENSOR NETWORKS 16 23>LS 24>DV 25>both 26>Dynamic Source Routing 27>Adhoc On-demand Distance Vector Routing 28>both 29>T 30>all 31>pull, push 32>T 33>smaller 34>topology control 35>greedy distance 36>compass 37>greedy distance 38>both 39>convex 40>Other Face Routing 41>OFR 42>Other Adoptive Face Routing 43>both 44>spanner, stretch factor 45>both 46>Relative Neighborhood Graph 47>RNG 48>Gabriel 49>Gabriel, RNG 50>both 51>Restricted Delaunay Graph 52>Localized Delaunay Triangulation 53>greedy distance, perimeter 54>Greedy Perimeter Stateless Routing 55>both 56>greedy distance, perimeter 57>Trajectory Based Forwarding 58>TBF 59>rumor 60>both 61>more 62>O(1/ ra ) 63>minimum energy broadcast 64>Minimum Spanning Tree 65>wireless multicast advantage 66>NP 67>6,12 68>T 69>Broadcast Incremental Power 70>Prim 71>Geographical & Energy Aware Routing 72>GEAR 73>both 74>delivery 75>Learning Real Time A 76>50,100,50,25,45 77>both 78>recursive geographic forwarding 79>restricted flooding VTU N O TESBYSR I
  • 18. WIRELESS SENSOR NETWORKS 17 80>restricted flooding 81>sink, source, interest 82>interval 83>duration 84>sink 85>gradient 86>sink 87>pull, push 88>T 89>data 90>reactive 91>T 92>rumor 93>rumor 94>ACQUIRE 95>ACQUIRE 96>ACQUIRE 97>Information Driven Sensor Querying 98>Geographic Hash Table 99>T 100>GPSR 101>T 102>less 103>T 104>T 105>T 106>data, node 107>all VTU N O TESBYSR I
  • 19. WIRELESS SENSOR NETWORKS 18 CHAPTER 4: INFRASTRUCTURE ESTABLISHMENT 1>The problem of__________ for a sensor network is how to set the radio range for each node so as to minimize energy usage, while still ensuring that the communication graph of the nodes remains connected and satisfies other desirable communication properties (topology control/traffic monitoring) 2>CTR stands for__________ 3>__________problem states "compute the minimum common transmitting range r such that the network is connected" (topology control/critical transmitting range) 4>The probabilistic theory best suited to the analysis of CTR is the theory of __________ (GRG/GLS) 5>GRG stands for__________ 6>In__________ setting, n points are distributed into a region according to some distribution, and then some aspect of the node placement is investigated (GRG/GLS) 7>If n points are randomly and uniformly distributed in the unit square, then the critical transmission range is, with high probability a: r=c.sqrt (n/logn) b: r=c.sqrt (logn/n) Ans: ___________ (a/b/either) 8>One should choose_____ ranges in areas of high node density and ______ranges in regions of low density (short/long) 9>The range assignment problem has been shown to be NP complete for dimensions __& above (1/2)_________ 10>___________MST based algorithms can be expensive to implement on typical sensor nodes (homogeneous/non-homogeneous/either) 11>Give example of protocol that can be used to directly solve the CTR problem in a distributed way: ___________ (COMPOW/COMPASS) 12>__________protocol computer routing tables of each node at different power levels and a node selects the minimum transmit power so that its routing table contains all other nodes (COMPOW/COMPASS) 13>___________allows hierarchical structures to be built on the nodes and enables more efficient use of scarce resources such as frequency spectrum, bandwidth and power (clustering/classification) 14>___________allows the same time or frequency division multiplexing to be reused across non- overlapping clusters (clustering/classification) 15>The more capable nodes can naturally play the role of __________ (cluster leader/cluster head) 16>__________are nodes that aid in passing traffic from one cluster to another (gradient/gateway) 17>___________can be used to thin out parts of the network where an excessive number of nodes may be present (classification/clustering) 18>Since the nodes in a sensor network operate independently , their clocks may not be or stay, synchronized with one another (true/false) ___________ 19>For time synchronization, the wired protocols assume the existence of highly accurate master clocks on some network nodes such as ___________ (skew clock/atomic clock) 20>In wireless sensor network a: no special master clocks are available b: connections are ephemeral c: communication delays are inconsistent and unpredictable Ans: ___________ (a/b/c/all) 21>Computer clocks are based on ___________oscillators which provide a local time for each sensor network node (software/hardware) 22>For a perfect hardware clock, the derivative dC (t)/dt should be___ to 1 (=/</>) 23>wrt clocks and communication delays, a typical value of p for today's hardware clock is 10-__ (3/6/9) VTU N O TESBYSR I
  • 20. WIRELESS SENSOR NETWORKS 19 24>___________can actually change over time due to environmental conditions such as temperature and humidity (clock atomic/clock skew) 25>Time difference caused by the lack of a common time origin are referred to as___________ (clock phase difference/clock bias) 26>The latency in channel can be decomposed into following components a: send time b: access time c: propagation time d: receive time Ans: ___________ (a/b/c/d/all) 27>Match the following Send time: this is the delay incurred while waiting for access to the transmission channel due to contention, collisions etc Access time: this is the time for message to travel across the channel to the destination node Propagation time: this is the time for the network interface on the receiver side to get the message and notify the host of its arrival Receive time: this is the time taken by the sender to construct the message ___________ 28>___________delay can be kept small by time stamping the incoming packet initiate the network driver's interrupt handler (receive time/send time/propagation time/access time) 29>Time synchronization can be propagated across the network by using a ___________tree favoring direct connections with reliable delays (binary/spanning) 30>In many situations involving temporal reasoning, the temporal ordering of events matters ______than the exact times when events occurred (less/more)_____ 31>___________methods provide a lightweight protocol that can be used to move clock readings around the network and perform temporal comparisons (interval/reference) 32>Time comparisons are not sufficient for all applications and mappings from event times to time intervals may quickly become useless if ___________increase the interval sizes beyond reasonable limits (long delay/multi-hop route/either) 33>RBS stands for___________ 34>The key idea of the ___________is to use the broadcast nature of the wireless communication medium to reduce delays and delay uncertainty in the synchronization protocol (interval method/RBS) 35>___________refers to the maximum offset between any pair of receiver nodes (group interval/group dispersion) 36>One way to estimate ___________among pairs of receivers is to do a least-squares linear regression among all the pair-wise measurements obtained for the two receivers in a sequence of reference broadcasts (clock skew/phase difference) 37>___________is a method that allow the nodes in a network to determine their geographic positions on their own as much as possible, during the network initialization process (self tracking/self localization) 38>___________is a method that allows other nodes to obtain the location of a desired node, after the initial phase in which each node discovers its own location (tracking service/location service) 39>The nodes that know their positions are called___________ (locatable/landmark) 40>Drawbacks of GPS a: GPS receivers can be expensive and difficult to incorporate into every sensor node for a number of practical reasons including cost, power consumption, large form factors b: GPS systems do not work indoor or under ford foliage or in other expectable conditions Ans: ___________ (a/b/both) 41>___________methods aim at estimating the distance of a receiver to a transmitter , by exploiting known signal propagation characteristics (interval/ranging) 42>RSS stands for___________ 43>___________technique can be used to estimate the RF signal strength at the receiver (RSS/RBS) 44>in general, localization to within a few meters is the best that can currently be attained with___________ methods (RSS/RBS) VTU N O TESBYSR I
  • 21. WIRELESS SENSOR NETWORKS 20 45>A way to estimate distance is to measure the time it takes for a signal to travel from sender to receiver, this can be multiplied by the signal propagation speed to yield distance. Such methods are called___________ technique (TDOA/TOA) 46>Since the exact time of transmission may be hard to know, a way to estimate distance is to measure the ___________at two receivers, which then lets us estimate the difference in distances between the two receivers and the sender (TDOA/TOA) 47>Local pairs of beacons can be used to estimate local propagation speed (true/false)___________ 48>___________is similar to the collaborative source localization (atomic multi-lateration/attribute based routing) 49>Collaborative multi-lateration proceeds by computing substructures of the network called___________ (spanning tree/collaborative sub-tree) 50>___________are sub-graphs of the full network graph in which there are enough constraints to make the localization problem sufficiently overdetermined that error accumulation is avoided (spanning tree/collaborative subtree) 51>Collaborative subtrees are built using the notion of ___________nodes (tentatively unique/temporally unique) 52>A node is called___________ during a multilateration sequence if its position can be uniquely determined , assuming the positions of the other nodes used as references are unique (tentatively unique/temporally unique) 53>___________algorithm is used to traverse the network from a given node and accumulate nodes that can form a collaborative subtree (regression/recursive) 54>APIT stands for___________ 55>___________test can be used for range-free localization (APIT/ADIT) 56>For any triplet of landmarks that a node can hear, if the node passes the___________ test with respect to these landmarks , then the node is declared to be in the triangle defined by the landmarks (APIT/ADIT) 57>APIT failures happen less than___% of the time (14/15/16)________ 58>___________is a mechanism for mapping from node IDs of some sort to node locations (tracking service/location service) 59>The Grid system uses a distributed location service termed___________ (GLS/GRG) 60>The key idea of___________ is to distribute the load so that each network node acts as a location server for a relatively small number of other nodes, most in its neighborhood (GLS/GRG) 61>___________provides a mapping from node IDs to node locations (GLS/GRG) 62>In GLS, if we have n nodes that are reasonably uniformly distributed in a field , then the depth of the quad-tree will be___________{O (logn) or O (logn+1)} 63>Nodes can be aggregated into clusters a: to better share resources, control redundancy b: to enable hierarchical tasking and control Ans: ___________ (a/b/both) 64>___________remain especially challenging problems in the adhoc deployment setting (synchronization/localization/both) 65>In location dependent systems such as the___________ indoor system, beacons in each room broadcast location information to listener nodes (cricket/hockey) ANSWERS 1>topology control 2>Critical Transmitting Range 3>CTR 4>GRG 5>Geometric Random Graph 6>GRG 7>b 8>short, long 9>2 10>ether 11>COMPOW 12>COMPOW VTU N O TESBYSR I
  • 22. WIRELESS SENSOR NETWORKS 21 13>clustering 14>clustering 15>cluster head 16>gateway 17>clustering 18>T 19>atomic clock 20>all 21>hardware 22>equal 23>6 24>clock skew 25>either 26>all 27>1-d 2-a 3-b 4-c 28>receive time 29>spanning 30>more 31>interval 32>either 33>Reference Broadcast System 34>RBS 35>group dispersion 36>both 37>self-localization 38>location service 39>landmark 40>both 41>ranging 42>Received Signal Strength 43>RSS 44>RSS 45>TOA 46>TDOA 47>T 48>atomic multi=lateration 49>collaborative subtree 50>collaborative subtree 51>tentatively unique 52>tentatively unique 53>recursive 54>Approximate Point In Triangle 55>APIT 56>APIT 57>14 58>location service 59>GLS 60>GLS 61>GLS 62>O(log n) 63>both 64>both 65>cricket VTU N O TESBYSR I
  • 23. WIRELESS SENSOR NETWORKS 22 CHAPTER 5: SENSOR TASKING AND CONTROL 1>_____sensor can be tasked to look for animals of a particular size and color. _____sensor can be tasked to detect the presence of a particular type of vehicle (acoustic/camera) 2>IDSQ stands for__________ 3>The purpose of a sensor system is to obtain information that is as extensive and detailed as possible about the unknown parts of the world state (true/false)__________ 4>When we know the relevant manifest variables defining the world state, then computing the answers to queries about the world state is a__________ problem (standard algorithm design/range assignment) 5>The standard algorithm design problem needs to be modified in the sensor network context because a: the values of the relevant manifest variables are not known but have to be sensed b: the cost of sensing different variables or relations of the same type can be vastly different c: frequently the value of a variable or a relationship between variables, may be impossible to determine using the resources available in the sensor network ns: __________ (a/b/c/all) 6>The online nature of sensing requires the use of methods such as___________ to account for the fact that the value of sensor readings cannot be known before they are made (competitive analysis/value of information/either) 7>The main idea of information based sensor tasking is to base sensor selection decisions on information content as well as constraints on resource consumption, latency and other costs (true/false)___________ 8>___________formulates the sensor tasking problem as a general distributed constrained optimization that maximizes information gain of sensors while minimizing communication and resource usage (IDSQ/IBST) 9>___________refers to the knowledge about the target state such as position and velocity (belief state/true state) 10>Following approaches can be used for localizing a stationary source and tracking a moving source a: a leader node might act as a relay station to the user, in which case the belief resides at this node for an extended time interval, and all information has to travel to this leader b: the belief itself travels through the network, and nodes are dynamically assigned as leaders Ans: ___________ (a/b/both) 11>Using___________ criterion, the leader node at the center always selects the nearest node among those whose measurements have not been incorporated (NP/NN) 12>__________based selection favors sensors along the longer axis of the covariance fit of residual uncertainty in localization (mutual information/Mahalanobis) 13>In __________sensor network systems, we must balance the information contribution of individual sensors against the cost of communicating with them (centralized/distributed)_ 14>For multimodal, non-Gaussian distributions, ___________measure provides a better characterization of the usefulness of sensor data (mutual information/Mahalanobis) 15>___________can be interpreted as the Kullback Leibler divergence between the belief after and before applying the new measurement (mutual information/Mahalanobis) 16>The appropriateness of a particular utility measure for a sensor selection problem depends on following factors a: the characteristics of the problem such as the data and noise models b: the computational complexity of computing the measure Ans: __________ (a/b/both) 17>_____measure is easy to compute, although limited to certain data models.______applies to multimodal distributions, but its computation requires expensive convolution of discrete points if one uses a grid approximation of probability density functions (mutual information/Mahalanobis) VTU N O TESBYSR I
  • 24. WIRELESS SENSOR NETWORKS 23 18>___________method is based on the cluster leader type of distributed processing protocol (IDSQ/IBST) 19>In IDSQ algorithm, arrange following steps in correct order a: follower nodes b: initial sensor reading c: initialization d: sensor selection e: belief quality Ans: ___________ (cbaed/cabde/cabed) 20>In the___________ based protocol , it is necessary to design efficient and robust algorithms for electing a leader, since typically more than one sensor may have detections about a target simultaneously (planar/leader) 21>In leader election protocol, arrange the following steps in correct order a: if there are one or more messages with an earlier time stamp, the node knows that it is not the leader b: if none of the messages contains earlier time stamps, but some message contains a time stamp identical to the node's detection time, the node compares the likelihood ratio.If the node's likelihood ratio is higher, the node becomes the leader c: if none of the messages is time stamped earlier than the node's own detection, the node declares itself leader Ans: ________ (bca/cba/cab) 22>In the leader based protocol, following different criteria can be used for choosing the next sensor a: nearest neighbor b: mahalanobis distance c: maximum likelihood d: best feasible region Ans: ___________ (a/b/c/d/all) 23>PIR stands for___________ 24>NN stands for___________ 25>A primary purpose of sensing in a sensor network is to collect and aggregate information about a phenomenon of interest (true/false)___________ 26>___________provides us with a method of selecting the optimal order of sensors to obtain maximum incremental information gain (IDSQ/IBST) 27>A user issues a query from an arbitrary node, which is called as___________ node, requesting the sensor network to collect information about a phenomenon of interest (query proxy/query processing) 28>Using the___________ measure, the querying node can determine which node can provide the most useful information while balancing the communication cost, w/o the need to obtain the remote sensor data first (mahalanobis distance/mutual information) 29>In a ___________belief carrier protocol, the belief is successively handed off to sensor nodes closest to locations where useful sensor data are being generated (static/dynamic) 30>In___________ belief carrier protocol, the current sensor node updates the belief with its measurement and sends the estimation to the next neighbor that it determines can best improve the estimation (static/dynamic) 31>The___________ algorithm fails due to its lack of knowledge beyond the immediate neighborhood (greedy/recursive) 32>Example of local routing algorithm is___________ (GPSR/GPRS) 33>In general, the information contribution of each sensor is state-dependent (true/false)___________ 34>Following are examples of standard shortest path algorithms on graphs___________ (dijkstra/bellman ford/both) 35>MSE stands for___________ 36>The error in localization, measured as mean squared error , generally ___________as more sensor measurements are incorporated (increases/decreases) 37>State dependency is an important property of sensor data aggregation, regardless of specific choices of information metrics (true/false)___________ 38>Search cost function is defined as the path cost___________ the information gain (plus/minus) VTU N O TESBYSR I
  • 25. WIRELESS SENSOR NETWORKS 24 39>To mitigate the combinational explosion problem, following strategies can be used a: we can restrict the search for optimal paths to a small region of the sensor network b: we can apply heuristics to approximate the costs so that they can be treated as additive Ans: ___________ (a/b/either) 40>In sensor network, the goal is to route a query from the query proxy to the exit point and accumulate as much information as possible along the way, so that one can extract a good estimate about the target state at the exit node and yet keep the total communication cost close to some prespecified amount (true/false)___________ 41>When it is possible to estimate the cost to go, the A* ___________method can be used (best first search/heuristic search) 42>The basic A* is a ___________search, where the merit of a node is assessed as the sum of the actual cost g paid to reach it from the query proxy , and the estimated cost h to pay to get to the exit node (depth first/best first) 43>For real-time path-finding, we use a variation of the A* method called ___________search (RTA/BFS) 44>RTA stands for___________ 45>In many applications, the physical phenomenon may be mobile, requiring the network to migrate the information according to the motion of the physical phenomenon for communication___________ reasons (efficiency/scalability/both) 46>In practical applications, the effect of a physical phenomena usually attenuates with distance, thus limiting the propagation of physical signals to geographical regions around the physical phenomenon (true/false)___________ 47>The physical phenomenon being sensed change over time (true/false)___________ 48>Geographically based group initiation and management have to be achieved by a___________ protocol distributed on all sensor nodes (greedy/lightweight) 49>Considering that the group membership is dynamic as the targets move and that the network is formed in an adhoc way such that no nodes have the knowledge of the global network topology. These difficulties may be tackled via following techniques a: leader based tracking algorithm where at any time each group has a unique leader who knows the geographical region of the collaboration b: recent advances in geographical routing that do not require the leader to know the exact members of its group Ans: ___________ (a/b/both) 50>The information based approach to sensor querying and data routing selective invokes sensors to___________ the number sensing actions needed for a given accuracy and hence latency & energy usage (minimize/maximize) 51>___________is a set of sensor nodes responsible for the creation and maintenance of a target's belief state over time, which we call track (co-operative group/collaborative group) 52>is a set of sensor nodes responsible for the creation and maintenance of a target's belief state over time, which we call ___________ (trunk/track) 53>How the leader node maintains and migrates the collaborative processing group. Arrange the following steps in correct order a: sensors are selected to acquire new measurements using the sensor selection algorithm b: after the leader is elected, it initializes a belief state as uniform disk centered at its own location_ c: as the target moves, the sensors that did not previously detect may begin detecting Ans: __________ (cba/acb/bca) 54>Following are examples of data association algorithms a: optimal assignment b: multiple hypothesis processing Ans: ___________ (a/b/both) 55>Using ___________algorithm , the ambiguities in the target identities after crossing tracks can be resolved using additional local evidence of the track identity and then propagate the information to other relevant tracks (identity management/data association) 56>We can convert global estimation and tracking problem into a local analysis using the so called___________ (primal dual transformation/parametric approximation) 57>A wireless sensor network is severely constrained by the on-board battery power (true/false)___________ VTU N O TESBYSR I
  • 26. WIRELESS SENSOR NETWORKS 25 58>If a sensor only wakes up, senses and communicates when it expects an event of interest, the power consumption of the network could be dramatically reduced (true/false)___________ 59>The idea of information driven sensor tasking, and its realization in IDSQ, is to base the sensor selection the potential contribution of a sensor to the current estimation task while using a moderate amount of resources (true/false)___________ 60>Following protocol can be used for sensing stationary or moving physical phenomena a: leader based b: moving center of aggregation Ans: ___________ (a/b/both) 61>In the resource limited sensor networks, the appropriate balance between the information and the costs is of paramount concern, since unnecessary data collection or communication consumes precious bandwidth and energy and overload human attention (true/false)___________ 62>Primary function of a senor network is to collect information from a physical environment (true/false)___________ 63>Routing an a sensor network must be co-optimized with the information aggregation or dissemination (true/false)___________ 64>___________group is an important abstraction of physical sensors, since individual sensors are ephemeral and hence less important, and sensors collectively support a set of tasks (co-operative processing/collaborative processing) 65>A major benefit of establishing the collaborative group abstraction is in enabling the programming of sensor networks to move from addressing individuals nodes to addressing collectives (true/false) ___________ ANSWERS 1>camera 2>Information Driven Sensor Querying 3>T 4>standard algorithm design 5>all 6>either 7>T 8>IDSQ 9>belief 10>both 11>NN 12>Mahalanobis 13>distributed 14>mutual information 15>mutual information 16>both 17>Mahalanobis , mutual information 18>IDSQ 19>cabed 20>leader 21>cab 22>all 23>Passive Infrared 24>nearest-neighborhood 25>T 26>IDSQ 27>query proxy node 28>Mahalanobis 29>dynamic 30>dynamic 31>greedy 32>GPSR 33>T VTU N O TESBYSR I
  • 27. WIRELESS SENSOR NETWORKS 26 34>both 35>Mean Squared Error 36>decreases 37>T 38>minus 39>either 40>T 41>heuristic search 42>best first 43>RTA 44>Real Time A* 45>both 46>T 47>T 48>lightweight 49>both 50>minimize 51>collaborative group 52>track 53>bca 54>both 55>identity management 56>spinal-dual transformation 57>T 58>T 59>T 60>both 61>T 62>T 63>T 64>collaborative processing 65>T VTU N O TESBYSR I
  • 28. WIRELESS SENSOR NETWORKS 27 CHAPTER 6: SENSOR NETWORK DATABASES 1>From a data storage point of view ,one may think of a sensor network as a distributed database that a; collects physical measurements about the environment b; indexes them c; serves queries from users and other applications external to or from within the network Ans; __________ (a/b/c/all) 2>The advantage of the database approach is that it provides a separation between the logical view of the data held by the sensor network and the actual implementation of these operations on the physical network (true/false)__________ 3>In a classical DBMS ,data is stored in a__________ location (centralized/distributed) 4>The structure and constraints of the data format are called database__________ (table/schema) 5>The database scheme are typically defined or modified by a database administrator using __________ (DML/DDL) 6>DDL stands for___________ 7>Today most databases employ relational schemas and their variants, organizing data into tables whose_____ are record tuples and whose______ are labeled by data attributes rows/columns) 8>___________compiler translates the definitions into metadata which is stored in permanent storage along with the actual data (DML/DDL) 9>___________is a data structure describing the structure of the database data and the constraints they must satisfy (metadata/temporal data) 10>In a typical database system ,the___________ directly controls storage devices such as disks and the flow of data between them and main memory (storage & buffer manager/transaction manager ) 11>The database is updated through units of work named___________ (transition/transaction) 12>It is the job of the__________ to guarantee that transactions are executed atomically and in apparent isolation from other transactions (storage & buffer manager/transaction manager) 13>A user queries the database in a high level logical query language such as___________ (Oracle/SQL) 14>A query is parsed by the_____ and translated into an optimized execution plan ,which is then processed by the______ to answer the user query (execution engine/query processor) 15>In any database system, there are trade offs between the speed of answering queries and the speed of performing database updates (true/false)___________ 16>In__________ database systems ,data storage may be allocated among several geographical separated locations ,connected by a communications network (centralized/distributed) 17>___________database makes the job of the query processor significantly harder (centralized/distributed) 18>Most query execution plans can be represented as trees where the_____ represent database operators and the______ correspond to producer-consumer relationships among operators (centralized/distributed) 19>P2P Stands for___________ 20>In___________ networks ,active processors can number in the tens to hundreds of thousands and may come on the network and go off the network at arbitrary times (P2P/PPP) 21>Another recent trend in database systems is to consider systems for data streams. Such systems are aimed at handling long running___________ queries such as may arise in network or traffic monitoring ,telecom call ,stock market transaction or web log record summarization (continuous/discontinuous) 22>Each sensor in a sensor network takes___________ measurements of physical phenomena such as heat, sound, light ,pressure or motion (time sequenced/time stamped) 23>The issue of where to store the data becomes of paramount importance since_____ dominates______ (energy landscape/communication cost) VTU N O TESBYSR I
  • 29. WIRELESS SENSOR NETWORKS 28 24>Following approaches can be used for implementing databases to support sensor network a; transfer all the data to one or a small number of external warehouses ,where traditional DBMS system could be deployed b; store the data within the network itself and allow queries to be injected anywhere in the network Ans; ___________ (a/b/both) 25>At the physical level, there are following major distinguishing characteristics of sensor networks when it comes to database implementation a; the network replaces the storage and buffer manager--data transfers are from data held in node memory as opposed to data blocks on disk b; node memory is limited by cost and energy considerations Ans; ___________ (a/b/both) 26>Following are challenges in sensor network databases a; the system as a whole is highly volatile b; relational tables are not static since new data is continuously being sensed c; the high energy cost of communication encourages in-networking processing during query execution d; access to data may be hampered by arbitrarily long delays and the rates at which input data arrives to a database operator can be highly variable Ans; ___________ (a/b/c/d/all) 27>Following are challenges in sensor network databases a; limited storage on nodes and high communication costs imply that older data has to be discarded b; sensor tasking interacts in numerous ways with the sensor database system c; classical metrics of database system performance ,such as throughput or delay may have to be adjusted in the sensor network context because of high variance in these quantities Ans; ___________ (a/b/c/all) 28>Following are differences between sensor network data and those of other databases at the logical level a; sensor network data consists of measurements from the physical world b; additional operators have to be added to the query language to specify durations and sampling rates for the data to be acquired c; while single shot queries are possible and useful in sensor networks ,we expect that a good fraction of the queries will be of the continuous ,long running type such as monitoring the average temperature in a room d; it is important to have operators for correlating sensor readings and comparing them with past statistics Ans; ___________ (a/b/c/d/all) 29>Sensor network differs from__________ networks in that nodes operate with limited energy ,processing and memory resources (data streams/P2P) 30>Sensor network differs from ___________networks in that geographic location can be of great importance in deciding what information to store and what information to query for (data streams/P2P) 31>It is advantageous to express queries to a sensor network database at a logical, declarative level ,using relational languages such as SQL (rue/false)___________ 32>In querying the physical environment ,___________level interfaces allow nonexpert users to easily interact with the database (low/high) 33>_____clause specifies the period during which data is to be collected, and the______ clause specifies the frequency at which the query results are returned (sampling period/duration) 34>There may be____ queries such as the report results over an extended time window ,___queries concerning the data in the network at a given point in time and____ queries that ask for aggregate information over historical data (snapshot/historical/continuous) 35>The queries on sensor networks may a; aggregate data over a group of sensors or a time window b; contain conditions restricting the set of sensors from contributing data c; correlate data from different sensors d; trigger data collection or signal processing on sensor nodes e; spawn subqueries as necessary Ans; ___________ (a/b/c/d/e/all) VTU N O TESBYSR I
  • 30. WIRELESS SENSOR NETWORKS 29 36>Not all users of a database system will be human operators (T/F)___. Programs running on the nodes themselves may generate queries in order to decide what sensing actions a node should take (T/F)___ 37>___________sensor network database system maintains an SQL-type query interface for users at a front end server connected to a sensor network (courage/cougar) 38>Distributed query execution is optimized for___________ (resource usage/reaction time/both) 39>Cougar represents each type of sensor in a network as an___________ ,as in most modern object-relational databases (ASN/ADT) 40>In Cougar database ,___________provides controlled access to encapsulated data through a well defined set of access functions (ASN/ADT) 41>An ADT object in the Cougar database corresponds to a___________ sensor in the real world (logical/physical) 42>STFT stands for___________ 43>The public interface of a seismic sensor ADT can comprise signal processing functions such as a; STFT b; vibration signature analysis Ans; ___________ (a/b/both) 44>___________relations are relations that are not actually materialized as ordinary table (base/virtual) 45>Cougar introduces_____ relations in contrast to the______ relations defined in the database schema (base/virtual ) 46>Cougar considers___________ query processing in the network (centralized/distributed) 47>Sensor data invariably contains measurement uncertainty due to ___________ (device noise/environmental perturbation/either) 48>GADT stands for___________ 49>___________models the uncertainty as a continuous probability distribution function over possible measurement values (ADT/GADT) 50>An operation named___________ primitive allow for probabilistic equality tests ,so one can meaningfully compare different Gaussian variables (Prob/Conf/Diff) 51>Range queries are another important class of sensor network queries (true/false)___________ 52>In the___________ warehousing approach ,each sensor forwards its data to a central server or warehouse connected to the network via an access point (centralized/decentralized) 53>Following are disadvantages of centralized warehousing a; the nodes near the distinct point become traffic hot spots and central points of failure plus they may be depleted of energy prematurely b; this approach does not take advantage of in-network aggregation of data to reduce the communication load when only aggregate data needs to be reported c; sampling rates have to be set to be the highest that might be needed for any potential query ,possibly further burdening the network with unnecessary traffic d; customers of the data may be other applications running on nodes themselves in the network Ans; ___________ (a/b/c/d/all) 54>In___________ approach, the data is stored within the network (centralized warehouse/in- network storage) 55>At the center of the___________ design is the appropriate choice of storage points for the data ,which act as rendezvous points between data and queries ,so that the overhead to store and access the data is minimized and the overall load is balanced across the network (centralized warehouse/in- network storage) 56>Features of the in-network storage a; allows data to be aggregated before it is sent to an external query b; takes advantage of locality of information for in-network queries c; load-balances the database costs across the nodes Ans; ___________ (a/b/c/all) 57>Following metrics can be used for general database systems a; network usage b; preprocessing time c; storage space requirement d; query time e; throughput f; update & maintenance cost Ans; ___________ (a/b/c/d/e/f/all) VTU N O TESBYSR I
  • 31. WIRELESS SENSOR NETWORKS 30 58>Match the following network usage; the time taken to construct an index preprocessing time; the storage for the data and index storage space requirement; the time taken to process a query ,assemble an answer ,and return this answer query time; the average number of queries processed per unit of time throughput; costs such as processing sensor data ,insertions ,dejections or repairs when nodes fail update & maintenance cost; it is characterized by total usage and hot spot usage 59>Network usage is characterized by______ which refers to the total number of packets sent in the network and_____ which refers to the maximal number of packets processed by any particular node (hot spot usage/total usage) 60>A sensor network database differs from a traditional centralized system in that a ; resources are severely constrained b; query processing is tightly coupled with networking and application semantics Ans; ___________ (a/b/both) 61>When designing a sensor database, we desire he following properties a; persistence b; consistency c; controlled access to data d; scalability in network size e; load balancing f; topological generality Ans; ___________ (a/b/c/d/e/f/all) 62>Match the following Persistence; the database architecture should work well on a broad range of network topologies Consistency; as the number of nodes increases ,the system's total storage capacity should increase Controlled access to data; a query must be routed correctly to a node where the data are currently stored Scalability in network size; data stored in the system must remain available to queries, despite sensor node failures and changes in the network topology Load balancing; different update operations must not undo one another's work ,and queries must always see a valid state of the database Topological generality; storage should not unduly burden any one node nor should any node become a concentration point of communication 63>In-network query processing can be used to provide substantial energy savings when serving aggregate queries. This saving is possible because a; separating data at intermediate nodes reduces the overall number of messages the network has to transmit ,thus reducing communication and prolonging the lifetime of the network b; combining data at intermediate nodes reduces the overall number of messages the network has to transmit ,thus reducing communication and prolonging the lifetime of the network Ans; ___________ (a/b/both) 64>In the___________ based approach ,the aggregation occurs at an external server ,each sensor sends its data directly to the server (client/server) 65>In-network aggregation and query processing typically involve___________ (query propagation/data aggregation/both) 66>A key challenge for in-network aggregation is the design of an optimal data aggregation schedule that is___________ efficient (energy/time/both) 67>___________provides an SQL-style declarative query interface, and implement aggregation mechanisms that are sensitive to resource constraints and loopy communication (TinyOS/TinyOS) 68>TinyDB supports following SQL operators a; count b; min c; max d; sum e; average Ans; ___________ (a/b/c/d/e/all) 69>TinyDB supports following extensions___________ (median/histogram/both) VTU N O TESBYSR I
  • 32. WIRELESS SENSOR NETWORKS 31 70>For______ operator, it can be shown that the size of the partial state record is proportional to the size of the data set it summarizes ,while in_____ operator ,the size correlates with statistical properties (median/histogram) 71>___________are distributive ,meaning the size of an intermediate state is the same as that of the final aggregate__________ is algebraic in that the partial state records are not themselves aggregates for the data set ,but are of constant size (max/min/count/average/sum) 72>_____is holistic and______ is content sensitive (median/histogram) 73>The performance of TinyDB is___________ related to the amount of intermediate state information required per aggregate (directly/inversely) 74>TinyDB uses ___________ based mechanism for data aggregation (emoge/epoch) 75>TinyDB builds a___________ tree for aggregation (static/dynamic) 76>In the query tree ,_____are the operators and______ are data dependencies among the operators (nodes/edges) 77>The task assignment problem is___________ complete (NP/PN) 78>A tree based query propagation mechanism is appropriate for a ___________based application (client/server) 79>DCS stands for___________ 80>____________is a method proposed to support queries from any node in the network by providing a rendezvous mechanism for data and queries that avoids flooding the entire network (DCE/DCS) 81>Directed diffusion is an example of data centric routing (true/false)___________ 82>At the center of a DCS system are___________ points ,where data and queries meet (rendezvous/meeting) 83>GHT stands for___________ 84>An instance of DCS is the ___________ (GLS/GHT) 85>in___________ ,the translation from node attributes to storage location is accomplished by a hash function ,which attempts to distribute data evenly across the network (GLS/GHT) 86>___________may be regarded as a variant of publish and subscribe except the event broker serves as the data storage and rendezvous point (DCS/DCE) 87>A type of query that is especially appropriate for sensor network databases is a __________query (range/boundary) 88>In___________ query ,a certain range is specified for a number of attributes of interest on the data sought (range/boundary) 89>In general ,sensor network data is multi-attribute (true/false)___________ 90>__________is aimed at point queries or exact matches, so it is not well suited for queries involving data ranges (GLS/GHT)_ 91>in general ,the complexity of answering a query in a sensor network will be a function of a; the size of the data in the network b; the number of records returned Ans; ___________ (a/b/both) 92>Following are classical measures of the quality of an index___________ (speed/size/both) 93>The ___________data the index stores ,the faster the query processing can be (less/more) 94>wrt one dimensional indices ,the particular subsets of data forming the prestored answers are referred to as the___________ subsets (orthogonal range/canonical) 95>In canonical subsets of sensors along a road ,an___________ node in the tree aggregates information from all its descendant sensors in th tree (internal/external) 96>Partial data aggregation is a key feature of any indexing scheme for range searching (true/false)___________ 97>When we have a set of attributes each parameterized by a scalar value and query with a interval along a subset of the parameters ,then we call this as___________ searching (orthogonal range/canonical) 98>Examples of hashing/partitioning schemes are___________ (grid files/partitioned hashing/both) 99>Examples of tree based index structure include a; multilevel indices b; k-d trees c; quad tree d; R trees Ans; ___________ (a/b/c/d/all) 100>The storage cost for storing m events into ___________is O (m) {k-d tree/multi level} VTU N O TESBYSR I
  • 33. WIRELESS SENSOR NETWORKS 32 101>Range searching indices provide a hierarchical summarization of records or events in the database according to simple attributes of interest (true/false)__________ 102>Wavelet transforms provide one way to compress and summarize information for both temporal and spatial signals ,and are widely used in__________ processing (signal/image/both) 103>__________is a system that provides multi-resolution storage and search for sensor data (DIAMETERS/DIMENSIONS) 104>DIFS stands for__________ 105>If we can partition aggregated data in a meaningful way, then we can distribute that data over several nodes in the network and thus lessen the load on nodes near the hierarchy root. A system that has developed this approach is__________ (DIPS/DIFS) 106>__________uses a modified GHT to find an index node (DIPS/DIFS) 107>The idea of storing information locally is at the heart of the__________ approach to storing data in a sensor network (fractional cascading/locality preserving hashing) 108>The key idea of the_________ approach is to store at each sensor information about data available elsewhere in the network ,but in such a way that a sensor knows only a fraction of the information from distant parts of the network (fractional cascading/locality preserving hashing) 109>Fractional cascading accomplishes following goals simultaneously a; the total amount of information duplication across all sensors is kept small because of the geometric decrease with distance b; the communication costs required to build this index and its update cost remain reasonable ,as on a the average information travels only short distances c; neighboring sensors have highly correlated world views ,this allows for smooth information gradients and enables local search algorithms to work well Ans; __________ (a/b/c/all) 110>DIM stands for__________ 111>__________approach is developed in the DIM system (fractional cascading/locality preserving hashing) 112>In__________ approach ,we map the attribute space to the plane so that nearby locations in attribute space correspond to nearby locations in the plane (fractional cascading/locality preserving hashing) 113>The key idea of __________is a clever construction of a locality preserving mapping between the multidimensional attribute space and the spatial domain of sensors (DIM/DIFS) 114>_____databases has to store static information while_____ databases must deal with continuous data acquisition and allow the temporal aspects of the data to be used in queries (traditional/sensor network) 115>The sensor data acquired by a single node over time can be processed and summarized directly on that node ,with no additional communication costs (true/false)___________ 116>One of disadvantage of sensor network is that overall node storage is very limited (true/false)__________ 117>The__________ system computes multi-resolution summaries of data (DIAMETERS/DIMENMSIONS) 118>__________is a monotonically decreasing function specifying acceptable query response accuracy as a function of data age (mining function/aging function) 119>KDS stands fo___________120>wrt indexing motion data, in __________setting ,the correctness of the index is certified by certain atomic predicates called certificates ,on the parameters defining the index (KDC/KDS) 121>__________approach incrementally tracks the index structure as objects move and can be used to answer queries about the current state of the world (KDC/KDS) 122>Following are general approaches to indexing motion data a; using time oblivious approach b; using KDS approach Ans; __________ (a/b/both) ANSWERS 1>all 2>T 3>centralized VTU N O TESBYSR I
  • 34. WIRELESS SENSOR NETWORKS 33 4>schema 5>DDL 6>Data Definition Language 7>row, column 8>DDL 9>metadata 10>storage & buffer manager 11>transaction 12>transaction manager 13>SQL 14>query processor, execution engine 15>T 16>distributed 17>distributed 18>node, edge 19>peer to peer 20>P2P 21>continuous 22>time-stamped 23>communication costs, energy landscape 24>both 25>both 26>all 27>all 28>all 29>data streams 30>P2P 31>T 32>high 33>duration, sampling period 34>continuous, snapshot, historical 35>all 36>T,T 37>cougar 38>both 39>ADT 40>ADT 41>physical 42>Short Time Fourier Transform 43>both 44>virtual 45>virtual, base 46>distributed 47>either 48>Gaussian ADT 49>GADT 50>diff 51>T 52>centralized 53>all 54>in-network storage 55>in-network storage 56>all 57>all 58>1-f 2-a 3-b 4-c 5-d 6-e 59>total usage, hot spot usage 60>both VTU N O TESBYSR I
  • 35. WIRELESS SENSOR NETWORKS 34 61>all 62>1-d 2-c 3-e 4-b 5-f 6-a 63>both 64>server 65>both 66>both 67>TinyDB 68>all 69>both 70>median, histogram 71>max, min, count & sum; average 72>median, histogram 73>inversely 74>epoch 75>static 76>node, edge 77>NP 78>server 79>Data Centric Storage 80>DCS 81>T 82>rendezvous 83>Geographic Hast Table 84>GHT 85>GHT 86>DCS 87>range 88>range 89>T 90>GHT 91>both 92>both 93>more 94>canonical subsets 95>internal 96>T 97>orthogonal range 98>both 99>all 100>k-d tree 101>T 102>both 103>DIMENSIONS 104>Distributed Index for Features in Sensor network 105>DIFS 106>DIFS 107>fractional cascading 108>fractional cascading 109>all 110>Distributed Index for Multi-dimensional data 111>locally preserving hash functions 112>locally preserving hash functions 113>DIM 114>traditional, sensor network 115>T 116>T 117>DIMENSIONS VTU N O TESBYSR I
  • 36. WIRELESS SENSOR NETWORKS 35 118>aging function 119>Kinetic Data Structure 120>KDS 121>KDS 122>both VTU N O TESBYSR I
  • 37. WIRELESS SENSOR NETWORKS 36 CHAPTER 7: SENSOR NETWORK PLATFORMS AND TOOLS 1>Following are different types of programming for sensor networks a: those carried out by end users b: those performed by application developers Ans: __________ (a/b/both) 2>_____may view a sensor network as a pool of data and interact with the network via queries.On the other hand, _____must provide users of a sensor network with the capabilities of data acquisition, processing and storage (end user/application developer) 3>CSIP stands for__________ 4>Following are different types of node centric programming interfaces a: imperative language, nesC b: dataflow style language, TinyGals Ans: __________ (a/b/both) 5>Following are examples of node level simulator a: ns-2 b: TOSSIM Ans: __________ (a/b/both) 6>___________centric programming gives programmers platform support for thinking in high level abstraction (node/state) 7>Sensor node hardware can be grouped into following categories a: augmented general purpose computers b: dedicated embedded sensor nodes c: system-on-chip (SoC) nodes Ans: ___________ (a/b/c/all) 8>Match the following augmented general purpose computers: smart dust, BWRC picoradio node and PASTA node dedicated embedded sensor nodes: Berkeley mote family, UCLA Medusa family, Ember nodes and MIT microAMP SoC nodes: low power PCs, embedded PCs, custom designed PC and various PDA___________ 9>COTS stands for 10>Compared with dedicated sensor nodes, PC like platforms are___________power hungry (less/more) 11>Which sensor node hardware has high processing capability a: augmented general purpose computers b: dedicated embedded sensor nodes c: SoC nodes Ans: ___________ (a/b/c) 12>Which platform typically use COTS chip sets with emphasis on small from factor, low power processing and communication, and simple sensor interfaces a: augmented general purpose computers b: dedicated embedded sensor nodes c: SoC nodes Ans: ___________ (a/b/c) VTU N O TESBYSR I
  • 38. WIRELESS SENSOR NETWORKS 37 13>Berkeley motes has gained wide popularity in the sensor network research community because of a: small form factor b: open source software development c: commercial availability Ans: __________ (a/b/c/all) 14>Figure7.1___________ 15>In MICA mote , the main micro-controller named___________ takes care of regular processing (intel/Atmel ATmega103L) 16>In MICA mote, the ATmega103L MCU has integrated____ kB flash memory and ___kB of data memory (4/64/512)___ 17>The RF communication on MICA motes uses the TR=____chip set operating at ____MHz band (916/1000/1024) 18>MICA motes implement a____ kbps transmission rate (40/60/80)_______ 19>MICA mote has maximum transmission range of about ___________feet in open space (100/200/300) 20>MICA motes support a ____pin I/O extension connector (50/51/52)_______ 21>figure7.3___________ 22>Radio transmission bear the maximum power consumption (true/false)___________ 23>Stand alone embedded systems do not scale up for the programming of sensor networks for following reasons a: sensor networks are large scale distributed systems, where global properties are derivable from program execution in a massive number of distributed nodes b: sensor network should be able to respond o multiple concurrent stimuli at the speed of changes of the physical phenomena of interest Ans: ___________ (a/b/both) 24>___________implies a conceptual model for programmers, with associated techniques for problem decomposition for the software designers (design platform/design methodologies) 25>_____supports a______ by providing design time language constructs and restrictions, and run time execution services (design platform/design methodologies) 26>Most design methodologies for sensor network software are___________ centric, where programmers think in terms of how a node should behave in the environment (state/node) 27>Following are representative examples of node-level programming tools___________ (TinyOS/TinyGALS) 28>___________aims at supporting sensor network applications on resource constrained hardware platforms such as the Berkeley motes (TinyOS/TinyGALS) 29>___________is a virtual machine for the Berkeley motes (MICA/mate) 30>Features of TinyOS a: have no file system b: supports only static memory allocation: implements a simple task model d: provides minimal device & networking abstractions e: takes a language based application development approaches Ans: ___________ (a/b/c/d/e/all) 31>TinyOS organizes components into layers, the_____ a layer is , the closer it is to the hardware; the______ a layer is, the closer it is to the application (lower/higher) 32>In TinyOS, tasks are non-preemptive (true/false)___________ 33>The execution of an interrupt handler is called___________ (event context/event scheduler) 34>___________is an extension of C to support and reflect the design of TinyOS v1.0 and above (TinyGALS/nesC) 35>___________provides a set of language constructs and restrictions to implement TinyOS components and applications (nesC/ns2) 36>Interfaces of a nesC component are classified as___________ interfaces (provides/uses) 37>_____interface is a set of method calls exposed to the upper layers while a______ interface is a set of method calls hiding the lower layer components (provides/uses) 38>In nesC component, _____call is a method call from a lower layer component to a higher layer component while a______ call is a method call from a higher layer component to a lower layer component (command/event) VTU N O TESBYSR I