4/11/2012. Outline. Routing Protocols for Ad Hoc Networks. Classification of Unicast Ad-Hoc Routing Protocols. Ad Hoc Networks.

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1 18759 Wireless Networks (2012-pring) urvey Routing Protocols for d Hoc Networks Jiun-RenLin and Yi-hun hou lectrical and omputer ngineering arnegie Mellon University Outline d-hoc networks Unicast d-hoc routing protocols OV: d-hoc On-emand istance Vector routing R: ynamic ource Routing GPR: Greedy Perimeter tateless Routing for wireless networks iscussion onclusion 1 2 d Hoc Networks No infrastructure, no centralized administration Mobility andwidth-constrained wireless links Power-constrained nodes MW Group No single routing protocol works well in all cases 3 lassification of Unicast d-hoc Routing Protocols Unicast d-hoc Routing Protocols ased on Routing Information Update Mechanism Proactive OV Reactive R Geographic Routing GPR 4 Proactive protocols Maintain routes independent of traffic pattern Traditional link-state and distance-vector routing protocols are proactive Reactive protocols etermine routes only if needed Geographic Routing Geographic location information for making routing decisions Unicast d-hoc routing protocols OV: d-hoc On-emand istance Vector routing R: ynamic ource Routing GPR: Greedy Perimeter tateless Routing for wireless networks OV Properties d hoc On-demand istance Vector(OV) Routing Only nodes on the route maintain routing information Route discovery RRQ (route request) RRP (route reply) Route maintenance RRR (route error) 5 6 1

2 ource Node Initiates Route iscovery Intermediate Node Receives RRQ RRQ RRQ RRQ RRQ 1. Node needs a route to 2. reate a Route Request (RRQ) 3. roadcast RRQ to neighbors RRQ s addressand seq# saddressandseq # Hop count (= 0) 1. Node receive RRQ 2. No routes to rebroadcast RRQ 3. Makes a reverse route entry for Reverse Route ntry est= NextHop = Hopcount=1 7 8 Intermediate Node Knows the Route ource Node Receives the RRP RRP RRQ Forward link RRQ RRQ RRP RRQ RRP Forward Route ntry 1. Node receive RRQ 2. (a) No routes to rebroadcast (b) Has a route to and the seq# for route to is >= s seq# in RRQ unicast RRP to 3. Makes a reverse route entry for 9 s address and seq# s address Hop count to (= 1) Reverse Route ntry est= NextHop = Hopcount=2 1. Node receive RRP, create a forward route entry 2. Forward links are setup when RRP travels along the reverse path 3. Route is not included in packet header 10 est= NextHop = Hopcount=3 RRP s address and seq# s address Hop count to (= 2) Recovery From Link rror roadcast the RR to Upstream RRR RRR RRR RRR RRR 1. Neighboring nodes send Hello Message periodically 2. bsence of Hello from (Timeout) Link between and breaks 3. sends a RRR (route error) to upstream neighbors (a) Lists is now unreachable (b) Increase the sequence number of 1. receives RRR (a) check is next hop to (b) delete route to and forward RR to 2. receives a RRR (a) check is next hop to (b) rediscover route and reset destination sequence number if needed

3 OV ource vs. Hop-by-Hop Routing dvantages Routes established only when required estinationsequence numbers help to find the freshest route The source and intermediate nodes only need to store the next-hop information (distance vector routing table) isadvantages Flooding of route requests Possiblecollisions of route requests Receivedinconsistent routes if the requested destination sequence number is very old PotentialRoute Reply storm problem and create control overhead Periodic beaconingfor (active) route maintenance Hop-by-Hop Routing ach packet carries the next-hop information Intermediate nodes use individual routing tables for forwarding ource Routing ach data packets carries the complete route to destination Intermediate nodes uses route information in the header for forwarding ynamic ource Routing(R) Route Maintenance RRP [,,,,] RRP [,] [,,,,] [] [,,] [,] RRP [,,,,] [] [] [,F] L [,,L] [,,,] [,F] RRP [,,,,] F G [,,L,G] [,F] Transmission of RRQ H Represents RRP ends a RRR back to [,] [] RRR RRR [] [,F] L [,F] F [,F] [,,] [,F,L] G [,F,L,G] [,,,] [,Y] Represent list of identifiers appended to RRQ H R Geographical Information? dvantages Routes maintained only when needed -lowercontrol overhead Route caching can further reduce route discovery overhead single route discovery may yield many routes to the destination isadvantages Packet header size grows with route length Flooding of route requests Possiblecollisions of route requests n intermediate node may send Route Reply using a stale cached route PotentialRoute Reply storm problem Promiscuous mode consumes more energy Mobility Faster and more accurate update of broken or invalid links Lower overhead of beaconing calability For R and OV, state proportional to the number of destination which a node forward data packets toward

4 Greedy Perimeter tateless Routing (GPR) Properties Use geographic information Routing decision can be made dynamically Two forwarding modes ssumptions ll nodes know their geographic locations (e.g. GP) ource node can determine the location of the destination (e.g. local registration or lookup service) Greedy Forwarding loset to GF fails (void) Perimeter Forwarding Forwarding through the right-hand rule Pick the next counter-clockwise edge to traverse xample : originates a packet to GPR Operations Greedy fails w u z w u z Greedy Forwarding Perimeter Forwarding x x Greedy works Have left local maxima Greedy fails Results in the tour x-u-z- Results in the tour x-u-z-w-u-x olution : remove (w,z) from graph iscussion Trade-off between Proactive and Reactive R vs. OV GPR: routing based on geographical information dvantages and isadvantages Trade-Off: Proactive or Reactive Latency of route discovery Proactive protocols have lower latency since routes are maintained at all times Reactive protocols have higher latency because a node needs to find a route when it has data to send Overhead of route maintenance Proactive protocols have higher overhead due to continuous route updating Reactive protocols have lower overhead since routes are maintained only if they are needed

5 Proactive or Reactive OV vs. R Which approach is better depends on the traffic and mobility patterns If most nodes always have data to send If mobility is high Proactive protocols may produce higher routing efficiency If only a few nodes have data to send If mobility is low Reactive protocols may produce higher routing efficiency OV Routes need not be included in packet headers t most one next-hop per destination maintained at each node Nodes maintain routing tables containing entries only for routes that are in active use Unused routes expire even if topology does not change Ondemand imilar route discovery process R May maintain several routes for a single destination oes not rely on any timer-based activities Regarding delay and throughput, R outperforms OV in less stressful situations Generates less routing packets than OV Geographical Routing Use of geographical position information Faster reaction to topology changes Limit the search area for finding a path calability Reduce control overhead Increase utilization Limitations? pplicability depends on the availability of GP or similar source of location information ssume the source can know the location of the destination Know and store the location of the neighbors onclusion Three routing protocols for wireless ad hoc networks ynamic ource Routing (R) d-hoc On emand distance Vector routing (OV) Greedy Perimeter tateless Routing for wireless networks (GPR) epending on the network size, traffic pattern, mobility, and network topology, people try to find the most suitable ad hoc routing protocol.g., use simulation tools to evaluate the performance of each routing protocol in terms of control overhead, throughput, packet delivery ratio, and delay Many existing studies evaluated the performance of several well-known routing protocol under different network conditions Reference Karp and H. T. Kung, GPR: Greedy Perimeter tateless Routing for Wireless Networks, Mobiom Johnson,. Maltzand J. roch, R: The ynamic ource Routing Protocol for Multi-Hop Wireless d Hoc Networks, In d Hoc Networking, edited by harles. Perkins, hapter 5, ddison-wesley, Perkins and. M. Royer. d hoc On-emand istance Vector Routing, Proceedings of the 2nd I Workshop on Mobile omputing ystems and pplications, New Orleans, L, February 1999, pp Johnson and. Maltz, ynamic ource Routing in d Hoc Wireless Networks, In Mobile omputing, Kluwer cademic Publishers, iva Ram Murthy,.. Manoj, d Hoc Wireless Networks rchitecture and Protocols, Prentice Hall, 2004 Military network figure in p.3 is from QUTION?