- Reservation schemes provide benefits like avoiding congestion and ensuring known waiting times by allocating transmission slots. - MAC protocols should maximize channel utilization, support different traffic types, and adapt to equipment failures and changing conditions. - CSMA/CD fails in wireless networks because collisions are detected at the receiver, not the sender, so the sender may not know a collision occurred. - A "hidden terminal" refers to nodes that are in range of a receiver but not each other, so they cannot detect when the other is transmitting and collisions may occur.

1. VELAMMAL INSTITUTE OF TECHNOLOGY
DEPARTMENT OF INFORMATION TECHNOLOGY
IT6601 – MOBILE COMPUTING
UNIT-I
INTRODUCTION
1. What are the benefits of reservation schemes? [April/May 2005]
a) No other station is allowed to transmit during this slot b) Avoidance of congestion.
c) Waiting time is clearly known.
2. Enumerate the properties of MAC protocols? [Nov/Dec 2010]
1) It should help maximize the utilization of the channel.
2) It should be capable of supporting several types of traffic having different maximum and
average bits rates.
3) It should be in the face of equipment failure and changing network conditions.
3. Why CSMA/CD scheme fails in wireless networks?
In Carrier Sense Multiple Access/Collision Detection, (CSMA/CD) collisions occur at the receiver
and not at the sender. The sender applies carrier sense and detects an idle medium. The sender starts
sending but a collision happens at the receiver due to a second sender. The sender detects no
collision and assumes that the data has been transmitted without errors, but a collision might actually
have destroyed the data at the receiver. The power in the area of the transmitting antenna is several
magnitudes higher than the receiving power.
4. Define hidden terminal. [Nov/Dec 2015]
The transmission range of A reaches B but not C. The transmission range of C reaches B but not A.
B reaches A and C. A cannot detect C and vice versa.
A starts sending to B, but C does not receive this transmission. C also wants to send something to B
and senses the medium. The medium appears to be free, the carrier sense fails. C also starts sending,
causing a collision at B. But A can’t detect this collision at B and continues with its transmission. A
is hidden for C and vice versa.
5. What is orthogonal and autocorrelation thickness? [Nov/Dec 2008]
Orthogonal: Two vectors are called orthogonal if their inner product is 0.
E.g.) the two vectors are(2,5,0) & (0,0,17): (2,5,0)* (0,0,17)=0+0+0.
Autocorrelation: The barker code (+1, -1, +1, +1, -1, +1, +1, +1, -1, -1, -1) for example has a good
autocorrelation (i.e.) the inner product with itself is large the result is 11.
6. Draw the taxonomy of MAC protocol?

2. 7. What is mobile computing? List out the characteristics of mobile computing. [A/M 11]
Mobile computing is the computational technique used for the people to access information from
anywhere and at anytime. It is also called as ubiquitous computing and also nomadic computing.
The characteristics of mobile computing are:
1]location awareness
2]Ubiquity
3]Adaptation
4]Broadcast
5]Personalization
8. Define CDMA. [Nov/Dec 2012]
Code Division Multiple Access systems use codes with certain characteristics to separate
different users. To enable access to the shared medium without interference. The users use the same
frequency and time to transmit data. The main problem is to find good codes and to separate this
signal from noise. The good code can be found the following 2 characteristic 1. Orthogonal. 2. Auto
Correlation.
9. What the features are of Code Division multiple Accesses?
It does not require external synchronization networks. • CDMA offers gradual degradation in
performance when the no. of users is increased But it is easy to add new user to the system. If offers
an external interference rejection capability.
10. How are guard spaces realized between users in CDMA?
The guard space between a pair of users in CDMA systems is the orthogonality between their
spreading codes. The lower the correlation between any pair of spreading codes is, the better is the
user separation.

3. 11. What are the several versions in CSMA? [Nov/Dec 2014]
There are several versions in CSMA, they are as follows
a) Non-persistent CSMA
b) p-persistent CSMA
c) 1-persistent CSMA
12. What is meant by non-persistent CSMA?
In, non-persistent CSMA, stations sense the carrier and start sending immediately if the medium
is idle, if the medium is busy, the station pauses a random amount of time before sensing the
medium again and repeating this pattern.
13. What is meant by p-persistent CSMA? [Nov/Dec 2014]
In p-persistent CSMA system nodes also sense the medium, but only transmit with a
probability of p. With the station deferring to the next slot with the probability1-p, i.e. access is
slotted in addition.
14. What is the difference between wireless networking(communication) and Mobile
computing? Or Distinguish between mobile computing and wireless networking.
15. What are applications of Mobile Computing? [Nov/Dec 2014]
• Vehicles
• Emergencies
• Business
• Replacement of wired networks
• Infotainment
• Location dependent services
• Follow-on services
• Location aware services

4. 16. What is the function of Medium Access Control Layer? [Nov/Dec 2013] or State the need
for Medium access control in network communication.
The functions of Medium Access Control Layer are responsible for establishes, maintains, and
releases channels for higher layers by activating and deactivating physical channels
17. Distinguish FDMA and TDMA [Nov/Dec 12]
Time division multiple access (TDMA) is a channel access method for shared medium (usually
radio) networks. It allows several users to share the same frequency channel by dividing the signal
into different time slots. This allows multiple stations to share the same transmission medium (e.g.
radio frequency channel) while using only a part of its channel capacity.
Frequency Division Multiple Access or FDMA is a channel access method used in multiple-access
protocols as a channelization protocol. FDMA gives users an individual allocation of one or several
frequency bands, allowing them to utilize the allocated radio spectrum without interfering with each
other.
18. Give the use of SDMA. What is SDMA? [May/Jun 2013]
Space Division Multiple Access (SDMA) is used for allocating separated spaces to users in
wireless networks. The basis for the SDMA algorithm is formed by cells and sectored antennas
which constitute the infrastructure implementing space division multiplexing (SDM).
19. What is the difference between CSMA CA and CSMA CD?
CSMA/CD: Carrier Sense Multiple Access / Collision Detection. When a collision is detected, all
the stations will stop transmitting and wait a random length of time before retransmitting. It is used
in Ethernet networks
CSMA/CA: Carrier Sense Multiple Access / Collision Avoidance. Instead of detecting and reacting
to collisions, CSMA/CA tries to avoid the collision by having each computer signal its intention to
transmit before the actual transmission. i.e Pre fixed timing for each station. It is used in Apple
networks and WiFi.
20. How MACA solves the exposed terminal problem? [Nov/Dec 2015]
By using MACA, B has to transmit an RTS(Ready to Send) first containing the name of the receiver
(A) and the sender (B). C does not react to this message as it is not the receiver, but A acknowledge
using a CTS (Clear to Send) which identifies B as the sender and A as the receiver of the data
transmission. C does not receive these CTS and concludes that A is outside the range. Therefore, C

5. can start its transmission assuming it will not cause a collision at A. Thus the problem with exposed
terminal is solved.
UNIT 2
MOBILE INTERNET PROTOCOL AND TRANSPORT LAYER
1. How do you classify TCPs? (May 2012)
a. TCP in single hop wireless networks
 Indirect TCP (I-TCP)
 Fast retransmission
 Snooping TCP(S-TCP)
 Mobile TCP(M-TCP)
 Freeze TCP
b. TCP in multihop wireless networks
2. What are the possible locations of tunnel end point in mobile IP? (June 2014) (Or)
What are the possible locations for care of Address? (Dec 2013)
Tunnel is a secure path from HA to FA that ensures the successful delivery of
packets to the MN.Care of Address is a termination point of a tunnel toward a MH, for
data grams forwarded to the MH while it is away from home.
1. Foreign agent care-of address: the address of a foreign agent that MH registers with
2. co-located care-of address: an externally obtained local address that a MH gets.
3. What should be the value of TTL field in the IP packet of agent advertisement? (June
2014)
The value of TTL field in the IP packet of agent advertisement is set to “1” for all
advertisements to avoid forwarding them.
4. What is Care of Address? Differentiate types of Care of Address. (Dec 2012)
Care of Address gives the current location of the mobile Node. There are two types of
CoA. They are:
• Foreign agent care-of address (FACoA): The mobile node receives the same CoA as
the foreign agent. All mobile nodes in the foreign network are given the same CoA.
• Co-located care-of address(Co-CoA): A mobile node acquires a co-located care-of
address as a local IP address through some external means, which the mobile node then
associates with one of its own network interfaces. The address might be dynamically
acquired as a temporary address by the mobile node, such as through DHCP.

6. 5. When and why binding update is generated in mobile IP? (May 2015(MP))
A binding is the association of the home address with a care-of address. Binding
Update (BU) message is used to notify the respective node about current location (CoA) of
the MN. BU is sent by HA to CN. The message contains the fixed IP address of the mobile
node and the care-of-address.
6. List the requirements for mobile IP. (Dec 2014(MP))
 Compatibility
 Transparency
 Scalability
 Efficiency and
 Security
7. List the advantages in transaction - oriented TCP. (Nov 2015) (June 2012)
1. RFC1644, T-TCP, describes a TCP version to avoid this overhead.
2. Connection setup, data transfer and connection release can be combined.
3. Thus, only 2 or 3 packets are needed.
4. It is highly efficient.
8. What advantage does the use of IPV6 offer for mobility?(Nov 2015)
IPv6 mobility provides a mechanism for the host to roam around different links
without losing any communication/connection and its IP address
9. What is Selective retransmission? (Dec 2012)
Selective retransmission allows for acknowledgements of single packets, not only
acknowledgements of in-sequence packet streams without gaps. Sender can now retransmit
only the missing packets
10. Why does I –TCP isolate problems on Wireless Link? (May 2013)
I-TCP splits the connection into two parts – a wired/fixed and a wireless/mobile
part. This isolates problems on the wireless link from the fixed network. However, this
also requires that intermediate systems are able to look into IP packets to split the
connection. This prevents the usage of IPsec – end-to-end security and I-TCP (or proxy
solutions in general) does not go together.

7. 11. What is Timeout freezing?(May 2013)
• Mobile hosts can be disconnected for a longer time - no packet exchange is
possible, e.g., in a tunnel, disconnection due to overloaded cells or mux.
• with higher priority traffic TCP disconnects after time-out completely
• TCP freezing
MAC layer is often able to detect interruption in advance
MAC can inform TCP layer of upcoming loss of connection
TCP stops sending, but does now not assume a congested link
MAC layer signals again if reconnected
12. Differentiate Snooping and mobile TCP.(Nov 2014)
Snooping TCP Mobile TCP
Foreign agent buffers all packets
with destination mobile host and
additionally snoops the packet flow
in both direction that is (MH-FA
and FA-CH)
Splits the TCP connection into an
unmodified TCP between the
standard host and supervisory host
(SH) and an optimized TCP
between the SH and MH. SH is
responsible for exchanging data
between both parts.
13. Define triangular routing.(Nov. 2015)
In the mobile IP, packets that are sent to a mobile host by the correspondent host are first
routed to the mobile host's home agent and then forwarded to the mobile host at its current
location by its home agent.
14. Give the advantages and disadvantages of Indirect – TCP. (May 2015)
Advantages of I-TCP:
 I-TCP segments a TCP connection into a fixed and wireless part.
 It does not require any changes in the TCP protocol.
 Transmission errors on wireless link do not propagate into the fixed network.

8.  Allows the use of a different transport layer protocol between foreign agent and
mobile host.
 Optimizations of new mechanisms are easy.
Disadvantages of I- TCP:
 Increased Handover Latency
 The Foreign agent must be a trusted entity.
 Loss of end-end semantics of TCP causes problems.
15. What is the use of DHCP? (May 2015)
DHCP is a Dynamic Host Configuration Protocol (DHCP) used to simplify the
installation and maintenance of networked computers. If a new computer is connected to
the network, DHCP can provide it with all the necessary information for full system
integration into the network.
16. Differentiate Foreign and Home Agent in Mobile IP technology. (Nov 2012)
Home Agent (HA)
• system in the home network of the MN, typically a router
• registers the location of the MN, tunnels IP datagrams to the COA
Foreign Agent (FA)
• system in the current foreign network of the MN, typically a router
• forwards the tunneled datagrams to the MN, typically also the default router for
the MN
17. What is generic routing encapsulation?
Generic routing encapsulation (GRE) is an encapsulation scheme which supports other
network protocols in addition to IP. It allows the encapsulation of packets of one protocol
suite into the payload portion of a packet of another protocol suite.
18. What is called the exponential growth of the congestion window? [Nov/Dec 09]

9. The sender always calculate congestion window for a window start size of the congestion
window is one segment. Sender sends one packet and waits for acknowledgement. If
acknowledgement arise it raises the level of congestion window by one. If sender sends two
packet if acknowledgement arises it raises the level of congestion window by two. This
scheme raises the level of congestion window every time the acknowledges come back,
which takes roundtrip time(RTT).This is called the exponential growth of the congestion
window.
19. What is Fast retransmit? [Nov/Dec 11]
In TCP, a receiver sends acknowledgements only if it receive any packets from the sender.
Thus receiving acknowledgements from a receiver shows additionally that the receiver
continuously receives something from the sender. Therefore, the gap in the packet stream is
not due to severe congestion, but a simple packet loss due to a transmission error. The sender
can now retransmit the missing packets before the timer expires. This behaviour is called fast
retransmit.
20. What is fast recovery? [Nov/Dec 11]
The receipt of acknowledgement shows that there is no congestion justifying slow start. The
sender can continue with the current congestion window. The sender performs a fast recovery
from the packet loss. This mechanism can improve the efficiency of TCP dramatically.
UNIT III
TELECOMMUNICATION SYSTEMS
1. Define GSM. [MAY/JUN 2007]
 GSM (Global System for Mobile communication) is a digital mobile telephony system that is
widely used in Europe and other parts of the world. GSM uses a variation of time division
multiple access (TDMA) and is the most widely used of the three digital wirelesstelephony
technologies (TDMA, GSM, and CDMA).
 GSM digitizes and compresses data, then sends it down a channel with two other streams of user
data, each in its own time slot. It operates at either the 900 MHz or 1800 MHz frequency band.
2. List the three different categories of services of GSM. [NOV/DEC 2007]
(or)

10. What are the types of services in GSM? [MAY/JUN 2014]
 Bearer services
 Tele services
 Supplementary services
3. What are the two basic classes of handover? [APR/MAY 2011]
There are two basic classes in handover:
Hard handover: Switching between different antennas or different system is performed at a certain
point in time.
Soft handover: This is a new real mechanism in UMTS compare to GSM and this only available in
FDD mode.
4. Distinguish between soft handover and hard handover? [APR/MAY 2010]
A hard handover is one in which the channel in the source cell is released and only then the channel
in the target cell is engaged. Thus the connection to the source is broken before or 'as' the connection
to the target is made—for this reason such handovers are also known as break-before-make.
A soft handover is one in which the channel in the source cell is retained and used for a while in
parallel with the channel in the target cell. In this case the connection to the target is established
before the connection to the source is broken, hence this handover is called make-before-break.
Hard Hand - Off
 Occurs in GSM
 Available in FDD / TDD modes
 Inter frequency handover, Inter system handover
Soft Hand - Off
 Occurs in UMTS
 Available only in FDD mode
 Macro diversity
5. What are the different control channels used in GSM? [NOV/DEC 2012]
The control channel groups in GSM are:
 Broadcast control channel (BCCH)
 Common control channel (CCCH)

11.  Dedicated control channel (DCCH)
6. What are the four types of handover available in GSM? [NOV/DEC 2011]
 Intra cell Handover
 Inter cell Intra BSC Handover
 Inter BSC Intra MSC handover
 Inter MSC Handover
7. Why are so many different identifiers/address needed in GSM? [MAY/JUNE2012]
Users of the GSM systems work with telephone numbers. That is all users should see. These phone
numbers are completely independent of the current location of the user. The system itself needs some
additional information; however, it must not reveal the identity of users. The international
identification of users is done with the IMSI (=country code + network code + subscriber ID). During
operation within a location area, only a temporary identifier, the TMSI is needed. This hides the
identity of a user. The TMSI is not forwarded to the HLR. But instead another temporary number
reflects the location and any roaming required is the MSRN is used internally by the system.
8. What are the security services offered by GSM? [NOV/DEC 2012]
The security services offered by GSM are:
 Access control and authentication.
 Confidentiality.
 Anonymity.
9. How is authentication done in GSM networks? [NOV/DEC 2013]
The GSM network authenticates the identity of the subscriber through the use of a challenge-response
mechanism. A 128-bit Random Number (RAND) is sent to the MS. The MS computes the 32-bit
Signed Response (SRES) based on the encryption of the RAND with the authentication algorithm
(A3) using the individual subscriber authentication key (Ki). Upon receiving the SRES from the
subscriber, the GSM network repeats the calculation to verify the identity of the subscriber.
If the received SRES agrees with the calculated value, the MS has been successfully authenticated
and may continue. If the values do not match, the connection is terminated and an authentication
failure is indicated to the MS.

12. 10. What are the advantages and disadvantages of GSM? [NOV/DEC 2014]
Advantages
 Communication
 Total mobility
 Worldwide connectivity
 High capacity
 High transmission quality
 Security functions
Disadvantages
 No end-to-end encryption of user data
 Reduced concentration while moving
 Electromagnetic radiation
 High complexity of system
 Several incompatibilities within the GSM standards
11. What are the services provided by supplementary services? [MAY/JUN 2009]
 User identification
 Call redirection
 Call forwarding
 Closed user groups
 Multiparty Communication
12. Distinguish between mobile terminated call and mobile originated call. [NOV/DEC 2011]

13. MOC-Mobile Originating Call
MTC-Mobile Terminating Call
The Mobile/MS which initiate a Call is known as MOC, whereas the destination Mobile/MS for
which the call has been initiate is known as MTC.
MOC: MS (A party)->BSC->MSC/VLR
MTC: MSC/VLR->BSC->MS (B party)
MOC starts from A party sending service request to core network
MTC starts when core network receives B number and start analysis for paging, or IAM sending
13. What is meant by GPRS? [NOV/DEC 2008]
The General Packet Radio Service provides packet mode transfer for applications that exhibit traffic
patterns such as frequent transmission of small volumes.
General Packet Radio Services (GPRS) is a packet-based wireless communication service that
promises data rates from 56 up to 114 Kbps and continuous connection to the Internet for mobile
phone and computer users.
14. What is meant by GGSN and SGSN? [NOV/DEC 2007]
GGSN is Gateway GPRS Support Node. It is the inter-working unit between the GPRS
network and external packet data networks. The GGSN is connected to external networks via the Gi
interface and transfers packets to the SGSN via an IPbased GPRS backbone network.
SGSN is Serving GPRS Support Node. It supports the MS via the Gb interface. The GSN is
connected to a BSC via frame relay.
15. What are the new components added to GPRS network? [MAY/JUN 2012]
Two new components, called Gateway GPRS Support Nodes (GSNs) and, Serving GPRS Support Node
(SGSN) are added.
16. Specify the functions provided by radio network subsystem (RNS). [MAY/JUN 2008]
 Radio channel ciphering
 Deciphering
 Handover Control
 Radio resource management

14. 17. Mention the advantages and drawbacks of GPRS. [MAY/JUN 2012 - ME]
Advantages
 Allow broadcast, multicast and unicast services
 Cheaper packet transfer for internet applications
 Needs no connection setup prior to data transfer
Disadvantages
 Needs additional hardware and software
18. Mention the applications of GPRS [NOV/DEC 2011 - ME]
 Communications—E-mail; fax; unified messaging; intranet/Internet access
 Value-added services—Information services; games
 E-commerce—Retail; ticket purchasing; banking; financial trading
 Location-based applications—Navigation; traffic conditions; airline/rail schedules; location
finder
 Vertical applications—Freight delivery; fleet management; sales-force automation
 Advertising
19. Define UMTS. [MAY/JUN 2010 - ME]
 The Universal Mobile Telecommunication System (UMTS) is a third generation (3G) mobile
communications system that provides a range of broadband services to the world of wireless and
mobile communications.
 UMTS delivers low-cost, mobile communications at data rates of up to 2 Mbps. It preserves the
global roaming capability of second generation GSM/GPRS networks and provides new
enhanced capabilities.
20. What are the advantages and disadvantages of UMTS? [MAY/JUN 2013 - ME]
Advantages:
 Overcrowding is relieved in existing systems with radio spectrum
 Bandwidth, security and reliability are more

15.  Provides interoperability among service providers
 Availability of fixed and variable rates
 Always online devices – 3G uses IP connectivity which is packet based
 Rich multi-media services are available
Disadvantages:
 Roaming and data/voice work together has not yet been implemented
 Needs different handset
 The cost of cellular infrastructure , upgrading base stations is very high
 Power consumption is high
 Requires closer base stations and are expensive
UNIT IV
PART A
1. What are the differences between AODV and the standard distance vector algorithm? Why are
extensions needed? [APR/MAY 2008]
AODV is capable of both unicast and multicast routing. It is a reactive routing protocol, meaning that it
establishes a route to a destination only on demand Routers use distance vectorbased routing protocols to
periodicallyadvertise the routes in their routing tables. Routing information exchanged between typical
distance vectorbased routers is unsynchronized and unacknowledged.
AODV is a reactive protocol. Route calculation is only performed if necessary. This improves scalability
under light load, but causes a higher initial latency.
2. What are the drawbacks of wired networks? [APR/MAY 2010]
 Running the wires from each room within the home can be a difficult task.
 Network cables can look disorganized.
 Network cables can disconnect or become faulty consequently causing the connection to fail.
 Adding more computers to a wired network may result in unexpected expense if you run out of
connections on your network and could slow down the network.
 All wired networks differ from each other. The most familiar type of wired network is an Ethernet
network.

16. 3. Distinguish between infrastructure and ad hoc networks. [NOV/DEC 2012]
Infrastructure networks not only provide access to other networks, but also include forwarding functions,
medium access control etc. In these infrastructure based wireless networks, communication typically
takes place only between the wireless nodes and the access point, but not directly between the wireless
nodes. Ad-hoc wireless networks, however ,do not need any infrastructure to work .Each node can
communicate directly with other nodes, so no access point controlling medium access is necessary.
4. Differentiate wired networks routing from ad-hoc wireless networks routing. [NOV/DEC 2011]
S.No Wired Networks Adhoc Networks
1 Nodes do not participate in packet routing Each node acts as a router
2 Topology is static Topology is dynamic
3 Simple IP-based addressing scheme is
deployed
Simple IP-based addressing scheme is
deployed
5. Mention certain situation where Ad hoc networks are the only choice. [NOV/DEC 2012]
 Instant requirements
 Natural disasters
 Remote areas
 Effectiveness
6. Write any two factors that affect the performance of Adhoc networking. [NOV/DEC 2013]
 Throughput
 Average routing overhead
 Power consumption
7. Discuss some of the routing metrics to be considered in a mobile network layer? [NOV/DEC 2007]
 HOP counting
 Destination sequence distance vector
 Dynamic source routing
 Least interference routing
8. Why is routing in multi-hop adhoc networks complicated? [MAY/JUN 2007]

17. Routing is complicated because of frequent topology changes, differentcapabilities of the nodes, varying
propagation characteristics. Further, no controlinstance can support routing.
9. What are the differences between wired networks and adhoc wireless networks related to routing?
[MAY/JUNE2012]
S.
No
Factor Wired Network Wireless Network
1
Asymmetric
links
Routing algorithm asymmetric Routing algorithm symmetric
2
Redundant links Less number of redundant links More number of redundant link
3
Interference Links exist only where a wire
exist
Links come and go depending
transmission characteristics.
10. What are adhoc networks? [MAY/JUN 2009]
A wireless ad-hoc network is a decentralized type of wireless network. The network is ad hoc because it
does not rely on a preexisting infrastructure, such as routers in wired networks or access points in
managed (infrastructure) wireless networks. Instead, each node participates in routing by forwarding data
for other nodes, and so the determination of which nodes forward data is made dynamically based on the
network connectivity. In addition to the classic routing, ad hoc networks can use flooding for forwarding
the data.
11. List out the some of the popular Routing protocols.[MAY/JUN 2010]
DSDV(Destination Sequence Distance Vector)
DSR(Dynamic Source Routing)
AODV(Ad-Hoc On Demand Vector Routing)
ZRP (Zone Routing Protocol)
Multicast Routing Protocol
12. Define VANET. [NOV/DEC 2010]
Vehicular Ad-Hoc Network, or VANET, is a form of mobile ad-hoc network, to provide communications
among nearby vehicles and between vehicles and nearest fixed equipment, usually described as roadside
equipment.
13. How VANET differs from MANET?[MAY/JUN 2012]
Similar to Mobile ad hoc networks (MANETs), nodes in VANETs self-organize and self-manage
information in a distributed fashion without a centralized authority or a server dictating the

18. communication. In this type of network, nodes engage themselves as servers and/or clients, thereby
exchanging and sharing information like peers. Moreover, nodes are mobile, thus making data
transmission less reliable and suboptimal.
Apart from these characteristics, VANETs possess a few distinguishing characteristics:
• Highly dynamic topology
• Frequently disconnected network
• Patterned Mobility
• Propagation Model
• Unlimited Battery Power and Storage
• On Board Sensors
14. What are the security requirements in VANET? [QB]
• Authentication
• Availability
• Non Repudiation
• Privacy
• Data verification
15. What is the difference between proactive and reactive routing protocol ? May/June 2015
A proactive routing protocol is also called a “table-driven” routing protocol. In this, nodes continuously
evaluate routes to all reachable nodes and attempt to maintain consistent, up-to-date routing information.
Therefore, a source node can get a routing path immediately if it needs one.Reactive routing protocols for
mobile ad hoc networks are also called “on-demand” routing protocols. In a reactive routing protocol,
routing paths are searched only when needed.

19. 16. Define DSR protocol. [NOV/DEC 2011]
• Dynamic Source Routing is a source initiated on-demand routing protocol for ad-hoc
networks.
• In this protocol, the nodes do not need to exchange the routing table information periodically,
which helps to reduce the bandwidth overhead associated with this protocol.
17. Define ZRP. [QB]
The Zone Routing Protocol is a hybrid protocol. It incorporates the merits of both on-demand
and proactive routing protocol. A routing zone comprises a few MANET nodes within a few
hops from the central zone. Within a zone, a table-driven routing protocol is used.
18. What are the design issues in ad hoc networks? May/June 2013
• Network size and node density
• Connectivity
• Network Topology
• User Traffic
• Operational Environment
• Energy Constraint
19. What are the characteristics/features of Adhoc networks? [QB]
• Lack of fixed infrastructure
• Dynamic Topologies
• Bandwidth constrained, variable capacity links

20. • Energy constrained operation
• Increased vulnerability
20. What are the important steps to be performed in the operation of DSDV?[MAY/JUN
2013]
• Each router in the network collects route information from all its neighbours.
• After gathering information, the node determines the shortest path to the destination
based on the gathered information.
• Based on the gathered information, a new routing table is generated.
• The router broadcasts this table to its neighbours. On receipt by the neighbours, the
node re computes their respective routing table.
• This process continues till the routing information becomes stable.
UNIT V
PART – A
1. What are the constraints of Mobile O/S? [QB]
The special constraints of mobile o/s are;
• Limited memory
• Limited screen size
• Miniature keyboard
• Limited processing power
• Limited battery power
• Limited and fluctuating bandwidth of the wireless medium
2. What are the requirements of Mobile O/S? [QB]
• Support for specific communication protocols
• Support for a variety of input mechanisms
• Compliance with open standards
• Extensive library support
3. Define Windows Mobile. [QB]

21. • Window Mobile operating system is based on Pocket PC 2000 and was targeted
as an operating system for mobile phones which the different vendors can use in
their cell phones.
4. What is palm OS? [QB]
• Palm OS is a Proprietary operating system that was developed by Palm
Computing .
• It was designed with the provision of a touch screen based graphical user
interface.
• It has an elementary memory management system, to keep the operating system
small and fast.
5. Define Symbian OS? [QB]
The key features of Symbian os are:
• It supports a number of communication and networking protocols including TCP,
UDP, PPP, DNS, FTP etc.
• It also supports pre-emptive multitasking scheduling and memory protection.
• Symbian is a micro kernel based operating system.
6. What is iOS? [QB]
• iOS is a closed and proprietary operating system fully owned and controlled by
Apple and not designed to be used by various mobile phones vendors on their
systems.
7. Define M-Commerce. [QB]
• Mobile Commerce involves carrying out an activity related to buying and selling
of commodities, service or information using the mobile hand-held devices.
8. What are the applications of M-Commerce? [QB]
• Business –to-consumer application
• Business-to-business application
9. State the functionalities of Mobile commerce framework? [QB]
• Mobile devices
• Mobile middleware
• Networks
• Host computers

22. 10. What are the advantages of M-Commerce? [QB]
• The benefits of using m-Commerce include customer convenience, cost saving
and new business opportunities.
• It provides the flexibility of anytime, anywhere shopping using a light weight
device.
• It can be highly personalized
11. What are disadvantages of M-commerce? [QB]
• It do not offer graphics of a PC.
• The users are constrained to use small screen and keyboard and low resolution
pictures and videos.
• The small screens of mobile devices limit the complexity of application.
12. What are the three popular types of mobile payment schemes? [QB]
• Bank account based
• Credit card based
• Micropayment.
13. What are the security issues in M-commerce? [QB]
• It is anticipated to introduce new security and privacy risks those found in theE-
commerce.
• It provides facility against risk of lost or theft.
14. Define micropayment. [QB]
• It is intended for payment for small purchases such as from vending machines.
• The mobile devices can communicate with the vending machine directly using a
Bluetooth or wireless LAN connection to negotiate the payment and then the
micropayment is carried out.
15. Define Android.[QB]
• Android is an operating system for mobile devices based on Linux.
• Android is used as open source software for mobile devices.
• Google embed its search engine into Android, the way Internet Explorer is
embedded into windows.
16. Draw the structure of Android.[QB]

23. Application Layer
Application Framework
Libraries and Runtime
Kernel
17. Define Blackberry OS.[QB]
Blackberry operating system is a proprietary operating system designed for blackberry
smartphones produced by Research In Motion Limited (RIM). Being a proprietary
operating system, details of its architecture have not been published. It provides a very
good email system.
18. What are the applications of M-Commerce?[QB]
• Advertising
• Comparison shopping
• Information about a product
• Mobile Ticketing
• Loyalty and payment services
• Catalogue shopping
19. Draw the structure of M-Commerce.[QB]

24. 20. What are the features required for a mobile device to enable mobile commerce?
[QB]
• Good internet connectivity
• Ability to dispatch rich content such as image.
• Have a good quality camera with auto focus.
• Ability to read the RFID tags.