Routing protocols are essential for wireless sensor networks to efficiently transmit collected sensor data to data sinks. The document discusses several challenges in designing routing protocols for wireless sensor networks and surveys different routing techniques including flat, hierarchical, and geographic routing. It provides LEACH and PEGASIS as examples of hierarchical routing protocols that use clustering and data aggregation to reduce energy consumption.

1. RoutingProtocols
forWireless
SensorNetworks
By:
Murtadha S. Al-Sabbagh
Supervised By:
Dr. Muhammed Najm Al-Salam

2. Overview
• Introduction
• Data Dissemination and Gathering
• Routing Challenges and Issues
• Routing Strategies for wireless networks
• WSN routing techniques
• WSN routing protocols comparison
• Protocol Selection

3. INTRODUCTION
• The main task of wireless sensor nodes is to sense and collect
data from a target domain, process the data, and transmit the
information back to specific sites where the underlying
application resides.
• Achieving this task efficiently requires the development of an
energy-efficient routing protocol to set up paths between
sensor nodes and the data sink.

4. DATA DISSEMINATION AND
GATHERING
• Data dissemination is a process by which data and queries for
data are routed in the sensor network.
• In a scope of data dissemination, a source is the node that
generates the data and a node that is interested in data is called
sink.
• Data gathering is to transmit data that has been collected by
the sensor nodes to the base station.

5. ROUTINGCHALLENGESANDDESIGNISSUES
1.Network Scale and Time-Varying Characteristics:
• the densities of the WSNs may vary widely, ranging from very
sparse to very dense.
• in many applications, the sensor nodes numbering in the
hundreds if not thousands, are deployed in an ad hoc and often
unsupervised manner over wide coverage areas.
• In these networks, the behavior of sensor nodes is dynamic and
highly adaptive .

6. ROUTINGCHALLENGESANDDESIGNISSUES
2. Resource Constraints:
• Energy is a key concern in WSNs, which must achieve a long
lifetime while operating on limited battery reserves.
• Also the WSN nodes have low technical specifications that
must be taken into consideration when designing a WSN
routing protocol.

7. ROUTINGCHALLENGESANDDESIGNISSUES
3. Sensor Applications Data Models:
• The data model describes the flow of information between the
sensor nodes and the data sink.
• These models depends on the nature of the application.
• The need to support a variety of data models increases the
complexity of the routing design problem.

8. ROUTINGSTRATEGIESINWIRELESS
NETWORKS
• Mobile Wireless Networks :
• Ad-hoc networks.
• WSNs.
• Ad-hoc networks have several protocols like :
1. Proactive strategy relies on periodic dissemination of routing
information to maintain consistent and accurate routing
tables across all nodes of the network.
2. Reactive strategy :establish routes to a limited set of
destinations on demand..
3. Hybrid strategy.

9. ROUTINGSTRATEGIESINWIRELESS
NETWORKS
• Ad-hoc networks routing protocols are not suited for WSNs for the
following reasons:
1. Ad-hoc networks tend to exhibit their least desirable behavior under
highly dynamic conditions.
2. Routing protocol overhead typically increases dramatically with
increased network size and dynamics.
3. A large overhead can easily overwhelm network resources.
Furthermore.
4. Traditional routing protocols operating in large networks require
substantial internodal coordination, and in some cases global
flooding.
5. Capabilities of the ad-hoc network nodes are relatively high
compared to sensor nodes
• New routing strategies are therefore required for sensor networks.

10. WSNRoutingTechniques
1. flat network architecture protocols in which all nodes are
considered peers.
2. Data-centric routing protocols use attribute-based naming,
whereby a source node queries an attribute for the
phenomenon rather than an individual sensor node.
3. Hierarchical routing protocols imposes a structure on the
network.
4. Location based protocols where location information is
needed in order to calculate the distance between two
particular nodes so that energy consumption can be
estimated.

11. 1.flatnetworkarchitecture
protocols
• all nodes are considered peers.
• A flat network architecture has several advantages, including
minimal overhead to maintain the infrastructure
• and the potential for the discovery of multiple routes between
communicating nodes for fault tolerance.

12. 1.1Flooding And Gossiping
• In flooding, each sensor receiving a data packet broadcasts it
to all of its neighbors and this process continues until the
packet arrives at the destination or the maximum number of
hops for the packet is reached.

13. 1.1Flooding And Gossiping

14. 1.1Flooding And Gossiping
• Gossiping is a slightly enhanced version of flooding where the
receiving node sends the packet to a randomly selected
neighbor, which picks another random neighbor to forward the
packet to and so on.
• Gossiping avoids the implosion problem by limiting the
number of packets that each node sends to its neighbor to one
copy.
• The latency that a packet suffers on its way to the destination
may be excessive, particularly in a large network.

15. 2.Data-centricProtocols
• A source node queries an attribute for the phenomenon rather
than an individual sensor node.
• The interest dissemination is achieved by assigning tasks to
sensor nodes and expressing queries to relative to specific
attributes.
• Different strategies can be used to communicate interests to
the sensor nodes, including broadcasting and attribute-based
multicasting.

16. 2.1SPIN
• Sensor Protocols for Information via Negotiation.
• The main objective of SPIN is to overcome the
shortcomings of conventional protocols like flooding.
• The basic property of this family of protocols are data
negotiation and resource adaptation.
• data negotiation requires that nodes running SPIN
‘‘learn’’ about the content of the data before any data are
transmitted between network nodes.

17. 2.1SPIN
• To carry out negotiation and data transmission, nodes
running SPIN use three types of messages:
• The first message type, ADV (advertise)
• The second message type, REQ (request)
• The third message type, DATA

18. 2.1SPIN
• Basic operation of SPIN

19. 2.1SPIN
• SPIN versions:
• SPIN-PP (Basic Handshake sequence)
• SPIN-EC (When a node energy level approaches the low
threshold, a node running SPIN-EC reduces its
participation in the protocol operations.)

20. 2.1SPIN
• SPIN-BC (Is designed for broadcast networks where the ADV
signal will reach all the sensors in the coverage area of the
source)
• SPIN-RL (Enhance its reliability and overcome message
transmission errors caused by a lossy channel). by periodic
broadcasting of ADV and REQ)

21. 2.2DirectedDiffusion
• Directed diffusion is a data - centric paradigm for sensor query
dissemination and processing that provides energy efficiency,
scalability, and robustness.
• In contrast to SPIN, in direct diffusion the sink is the node that
broadcast the request for a specific data throughout the
network in what is called an “ interest message”.
• A gradient can be thought of as a reply link pointing toward
the neighboring node from which the interest is received.

22. 2.2DirectedDiffusion

23. 3.HierarchicalProtocols
• The main aim of hierarchical routing is to efficiently maintain
the energy consumption of sensor nodes by:
• involving them in multi-hop communication within a
particular cluster.
• performing data aggregation and fusion in order to decrease
the number of transmitted messages to the sink.

24. 3.1LEACH
• Low-energy adaptive clustering hierarchy (LEACH) is one of
the most popular hierarchical routing algorithms for sensor
networks.
• The idea is to form clusters of the sensor nodes based on the
received signal strength and use local cluster heads as routers
to the sink.
• The main objectives of LEACH are:
1. Extension of the network lifetime
2. Reduced energy consumption
3. Use of data aggregation to reduce the number
of communication messages

25. 3.1LEACH
• Cluster heads change randomly over time in order to balance
the energy dissipation of nodes.
• The LEACH operation can be depicted by the following two
phases:
• 1.setup phase: In which the cluster head selection is performed.
• 2.steady-state phase: In which data collection, aggregation and
delivery to the base station happens.

26. 3.2PEGASIS
• Power-efficient gathering in Sensor Information Systems
(PEGASIS) is an improvement of the LEACH protocol.
• Rather than using a tree or star hierarchy as in the LEACH
protocol , the PEGASIS protocol uses chain hierarchy.
• Data aggregation is carried out by :
• 1. The chain leader (3) issues a token to the right most node
telling it to send its sensing information, when the request
reaches node (7) it sends the information to node (6) where this
one aggregate its information to it and consequently until the
aggregated information reaches node (3)
• 2.Node (3) issues the same operation to the left most node and
after having all the information from the left and right sided
sends the aggregated information to the sink.
43 5 6210 7

27. 3.2PEGASIS
• The sequential approach discussed before is not practical and
consumes time.
• A better approach would be using parallelism in aggregation.
• In this approach node can use CDMA to work simultaneously
and not interfere with each other.
• Starting from the bottom up in the figure:
• First each node send its date to the
neighbor odd node.
• Secondly each odd node sends its data.
• Last node 7 send its aggregated data to
Node 3.
7

28. 4.Locationbasedprotocols
• The main objective of geographical routing is to use location
information to formulate an efficient route search toward the
destination.
• Geographical routing is very suitable to sensor networks,
where data aggregation is a useful technique to minimize the
number of transmissions toward the base station by eliminating
redundancy among packets from different sources.

29. 4.1GeographicRouting
• A node knows its own location, the locations of its neighbors, and the
destination’s location (D)
• The destination’s location is included in the packet header
• Forwarding decision is based on local distance information
• Greedy Forwarding: achieve max progress towards D
x D
y
Greedy Forwarding

30. 4.1GeographicRouting
• Greedy forwarding
• Next hop is the neighbor that gets the packet closest to destination
• Greedy forwarding can lead into a dead end, where there is no
neighbor closer to the destination.
destination
source

31. 4.1GeographicRouting
• The solution is to use a combination of greedy routing with
what called (face routing), where the latter is a technique of
routing that rout packets on the faces of the path
• Figure below illustrates face routing .

32. WSNroutingprotocols
comparison
• LEACH, PEGASIS, SPIN, DD, Geographical routing
comparison below :

33. RoutingProtocolsSelectionfor
particularapplications
• LEACH, PEGASIS, SPIN, DD, Geographical routing
comparison below :

34. Thank you ^_~