mobile ad hoc networks coe 549 routing protocols i

**Mobile Ad hoc Networks COE 549Routing Protocols ITarek SheltamiKFUPMCCSECOEwww.ccse.kfupm.edu.sa/~tarek

Communication Networks

Outline**Routing Algorithms ClassificationsProactive Routing:Table Driven ProtocolsCluster-based Protocols


15/4/2003*Routing Algorithm ClassificationsRouting AlgorithmsProactiveReactive Table Driven Cluster-based On-DemandHybrid Cluster-based


Table Driven Protocols**Distance Vector Protocols such as:Wireless Routing Protocol (WRP) [MUR96]Destination Sequenced Distance Vector (DSDV) routing protocol [PER94]Least Resistance Routing (LRR) [PUR93]The protocol by Lin and Liu [LIN99]. Link State Protocols such as:Global State Routing (GSR) [CHE98]Fisheye State Routing (FSR) [PEI00a]Adaptive Link-State Protocol (ALP) [PEI00a]Source Tree Adaptive Routing (STAR) [ACE99]Optimized Link State Routing (OLSR) protocol [SHE03b]Landmark Ad Hoc Routing (LANMAR) [PEI00b]However the most prominent protocol is DSDV


Table Driven Protocols**Try to match the link state and distance vector ideas to the wireless environmentEach node only needs to know the next hop to the destination, and how many hops away the destination is:This information stored in each node is often arranged in a table, hence the term table-driven routingSuch algorithm are often called distance vector algorithms, because nodes exchange vectors of their known distances to all other nodesAn example is the Bellman-Ford algorithm, one of the first ones to be used for routing in the Internet


Bellman-Ford Algorithm**Consider a collection of nodes, connected over bi-directional wired links of given delays.We want to find the fastest route from each node to any other node.An example network:

Initially, each node knows the distances to its direct neighbors, and stores them to its routing table. Nodes other than their direct neighbors are assumed to be at an infinite distance.Then, nodes start exchanging their routing tables.


Stage 1**


Stage 2**


Stage 3**


Table Driven Protocols**As the number of nodes n increases, the routing overhead increases very fast, like O(n2).When the topology changes, routing loops may form:


Destination Sequenced Distance Vector (DSDV)**One of the earlier ad hoc routing protocols developedIts advantage over traditional distance vector protocols is that it guarantees loop freedomExtends the classical DBF by tagging each distance entry dik(j) by a sequence number (SN) that is originated by the destination node j.Each routing table, at each node, contains a list of the addresses of every other node in the networkAlong with each nodes address, the table contains the address of the next hop for a packet to take in order to reach the nodeIn addition to the destination address and next hop address, routing tables maintain the route metric and the route sequence number.


Destination Sequenced Distance Vector (DSDV)..**The update packet starts out with a metric of oneThe neighbors will increment this metric and then retransmit the update packet.This process repeats itself until every node in the network has received a copy of the update packet with a corresponding metricIf a node receives duplicate update packets, the node will only pay attention to the update packet with the smallest metric and ignore the rest


Destination Sequenced Distance Vector (DSDV)..**To distinguish stale update packets from valid ones, the original node tags each update packet with a sequence numberThe sequence number is a monotonically increasing number, which uniquely identifies each update packet from a given nodeIf a node receives an update packet from another node, the sequence number must be equal to or greater than the sequence number already in the routing table; otherwise the update packet is stale and ignoredIf the sequence number matches the sequence number in the routing table, then the metric is compared and updated as previously discussed


15/4/2003*DSDV Routing Protocol


Sign

Metric #

4

Seq #

8

2

1

3

4

DEST

Next hop

2

1

3

4

15/4/2003*DSDV Routing Protocol


Laptop computer

1

4

1

DEST

Next hop

2

1

3

4

4

4

6

15

15/4/2003*Disadvantages of DSDV ProtocolRouting is achieved by using routing tables maintained by each nodeThe bulk of the complexity in generating and maintaining these routing tables If the topological changes are very frequent, incremental updates will grow in sizeThis overhead is DSDVs main weakness, as Broch et al. [BRO98] found in their simulations of 50-node networks


Virtual Base Station (VBS)All nodes are eligible to become clusterhead / VBSEach node is at one hop from its clusterheadClusterhead / VBS is selected based on the smallest IDGateways / Boarder Mobile Terminals (BMTs)Clsuterheads and Gateways form the virtual backbone of the network


VBS..Every MT has an ID number, sequence number and my_VBS variableEvery MT increases its sequence number after every change in its situation An MT my_VBS variable is set to the ID number of its VBS; however, if that MT is itself a VBS, then the my_VBS variable will be set to 0, otherwise it will be set to 1, indicating that it is a VBS of itself


VBS..


VBS Illustrated


VBS Illustrated..


CGSR infrastructure CreationCGSR uses the Least Cluster Change (LCC) clustering algorithm No clusterheads in the same transmission rangeEach Cluster has a different code to eliminate the interference, typically the suggest 4 Walsh codes


CGSR Illustrated


CGSR Illustrated ..


CGSR Illustrated..


Simulation Results


Chart1

4341

5245

6753

7554

VBS

CGSR

Number of nodes in the network

Average number of VBS's / clusterheads

Sheet4

1003024fig 13

2004930

4005035

6005236

Sheet4

00

00

00

00

VBS

CGSR

Number of Nodes in the Network

Nodes elected VBS / Clusterhead

Sheet1

1007069fig 9

2008081

4007258

60011656

Sheet1

00

00

00

00

VBS

CGSR

Number of nodes in the Network

Average VBS / clusterhead duration (secconds)

Sheet2

1004341fig 8

2005245

4006753

6007554

Sheet2

00

00

00

00

VBS

CGSR



Sheet3

1005848

2004019

4002018

600259

Sheet3

00

00

00

00

VBS

CGSR


Average zone nodes membership duration (seconds)

Simulation Results


Chart4

7069

8075

7258

11656

VBS

CGSR



Sheet4

1003024fig 13

2004930

4005035

6005236

Sheet4

00

00

00

00

VBS

CGSR



Sheet1

1007069fig 9

2008075

4007258

60011656

Sheet1

00

00

00

00

VBS

CGSR



Sheet2

1004341fig 8

2005245

4006753

6007554

Sheet2

00

00

00

00

VBS

CGSR



Sheet3

1005848

2004019

4002018

600259

Sheet3

00

00

00

00

VBS

CGSR



Simulation Results..


Chart6

5848

4019

2012

259

VBS

CGSR


Average zone MT's / nodes membership duration (seconds)

Sheet4

1003024fig 13

2004930

4005035

6005236

Sheet4

00

00

00

00

VBS

CGSR



Sheet1

1007069fig 9

2008075

4007258

60011656

Sheet1

00

00

00

00

VBS

CGSR



Sheet2

1004341fig 8

2005245

4006753

6007554

Sheet2

00

00

00

00

VBS

CGSR



Sheet3

1005848

2004019

4002012

600259

Sheet3

00

00

00

00

VBS

CGSR



Simulation Results..


Chart1

3024

4930

5035

5236

VBS

CGSR



Sheet5

Sheet4

1003024fig 13

2004930

4005035

6005236

Sheet4

00

00

00

00

VBS

CGSR



Sheet1

1007094fig 9

2008081

4007285

60011641

Sheet1

00

00

00

00

VBS

CGSR


Average VBS \ clusterhead duration (secconds)

Sheet2

1004341fig 8

2005245

4006753

6007554

Sheet2

00

00

00

00

VBS

CGSR



Sheet3

1005820

2004030

4002050

6002560

Sheet3

00

00

00

00

VBS

CGSR



15/4/2003*Routing in VBSSome issues about pure Cluster-based Routing (VBS)


15/4/2003*Some issues about pure Cluster-based Routing (VBS)


15/4/2003*Routing in VBSSome issues about pure Cluster-based Routing (VBS)


Drawback of VBS**All the nodes require the aid of their VBS(s) all the time, so this results a very high MAC contention on the VBSsthe periodic hello message updates are not efficiently utilized by MTs (other than VBSs and BMTs)The power of the nodes with small IDs drain down much faster than that with large IDs


mobile ad hoc networks coe 549 routing protocols i

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