8/7/20151 Mobile Ad hoc Networks COE 549 Routing Protocols I Tarek Sheltami KFUPM CCSE COE

Outline 8/7/20152  Routing Algorithms Classifications  Proactive Routing:  Table Driven Protocols  Cluster-based Protocols

15/4/20033 Routing Algorithm Classifications Routing Algorithms Proactive Reactive  Table Driven  Cluster-based  On-Demand Hybrid  Cluster-based

Table Driven Protocols 8/7/20154  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 8/7/20155  Try to match the link state and distance vector ideas to the wireless environment  Each 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 routing”  Such algorithm are often called distance vector algorithms, because nodes exchange vectors of their known distances to all other nodes  An example is the Bellman-Ford algorithm, one of the first ones to be used for routing in the Internet

Bellman-Ford Algorithm 8/7/20156  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 8/7/20157

Stage 2 8/7/20158

Stage 3 8/7/20159

Table Driven Protocols 8/7/  As the number of nodes n increases, the routing overhead increases very fast, like O(n 2 ).  When the topology changes, routing loops may form:

Destination Sequenced Distance Vector (DSDV) 8/7/  One of the earlier ad hoc routing protocols developed  Its advantage over traditional distance vector protocols is that it guarantees loop freedom  Each routing table, at each node, contains a list of the addresses of every other node in the network  Along with each node’s address, the table contains the address of the next hop for a packet to take in order to reach the node  In 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).. 8/7/  The update packet starts out with a metric of one  The 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 metric  If 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).. 8/7/  To distinguish stale update packets from valid ones, the original node tags each update packet with a sequence number  The sequence number is a monotonically increasing number, which uniquely identifies each update packet from a given node  If a node receives an update packet from another node, the sequence number must be greater than the sequence number already in the routing table; otherwise the update packet is stale and ignored

15/4/ DSDV Routing Protocol

15/4/ DSDV Routing Protocol

15/4/ Disadvantages of DSDV Protocol Routing is achieved by using routing tables maintained by each node  The bulk of the complexity in generating and maintaining these routing tables  If the topological changes are very frequent, incremental updates will grow in size  This overhead is DSDV’s 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 / VBS Each node is at one hop from its clusterhead Clusterhead / VBS is selected based on the smallest ID Gateways / 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 variable Every 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 Creation CGSR uses the Least Cluster Change (LCC) clustering algorithm No clusterheads in the same transmission range Each Cluster has a different code to eliminate the interference, typically the suggest 4 Walsh codes

CGSR Illustrated

CGSR Illustrated..

Simulation Results

Simulation Results..

15/4/ Range of node #1 Routing in VBS Some issues about pure Cluster-based Routing (VBS)

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

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

Drawback of VBS 8/7/  All the nodes require the aid of their VBS(s) all the time, so this results a very high MAC contention on the VBSs  the 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

36 Nodes Classifications: myCH = 0  Clusterhead myCH = -1  Free node myCH > 0  Zone_MT WEAC Infrastructure Creation Protocol 4/29/2008 An MT is eligible to be a clusterhead and willing to accept other MTs to be under its supervision if these MTs have a lower EL An MT ignores any merge request messages that are sent to it by other MTs. However, if the MT is serving as a clusterhead, it will remain a clusterhead If an MT is serving as a clusterhead, it sets its warningThreshold flag to true, informing its zone_MTs to look for another clusterhead, nonetheless, they can remain with it till its BPL drains down to THRESHOLD_3 An MT ignores any merge request messages and will send iAmNoLongerYourCH message to all the nodes under its supervision, if it was serving other nodes

List of MTs 5 WEAC Infrastructure Creation Protocol.. Merge REQ Merge Accpt. myCH = 20myCH = -1 myCH = BPL > THRESHOLD_1 BPL < THRESHOLD_1 An MT sends a merge-request message to another MT if the latter has a higher energy level and it should be > Threshold_1 8/7/201537

WEAC Infrastructure Creation Protocol.. 8/7/201538

8/7/ WEAC Infrastructure Creation Protocol..

8/7/ WEAC Infrastructure Creation Protocol..

Broadcasting The Neighbor List 8/7/201541

Selecting Gateways The least number of neighbors method The highest energy level method The Gateway Selection Algorithm 8/7/201542

The Gateway Selection Algorithm 1.if(there is more than one access to DEST){ 2. Select the MT with EL > THRESHOLD_2; 3. if(more than one with EL THRESHOLD_2){ 4. getTheLeastNumberOfNeighbors(); 5. select the one with the least number of neighbors; 6. } 7. elseif(MTs EL < THRESHOLD_2) 8. choose the one with the highest EL(); } 8/7/201543

Table update for zone_MTs 1.if(myCH > 0) 2. if(DEST my neighbor || DEST my neighbor’s neighbor){ 3. set this neighbor as the next hop; 4. if(more than one neighbor to the DEST) 5. run Gateway Selection Algorithm(), 6. } 7. else 8. set myCH as the next hop 8/7/201544

Table update for clusterheads and free_MTs 1.if(myCH ≤ 0) 2. update routing table according to the received tables 3. if(the DEST my neighbor || my neighbor ’ s neighbor){ 4. set this neighbor as the next hop 5. if(more than one neighbor to the DEST) 6. run Gateway Selection Algorithm(); } 7. else if(available route to the DEST) 8. keep the current route till the next update; 9. else 10. set the DEST to null; 8/7/201545

Simulation Results 8/7/201546

Simulation Results.. 8/7/201547

Simulation Results.. 8/7/201548

Simulation Results.. 8/7/201549