november 4, 2003applied research laboratory, washington university in st. louis apoc 2003 wuhan,...

November 4, 2003 Applied Research Laboratory, Washington University in St. Louis

APOC 2003Wuhan, China

Cost Efficient Routing in Ad Hoc Mobile Wireless Networks

Ruibiao [email protected]

Applied Research Laboratory, Washington University in St. Louis

2/10APOC 2003Wuhan, China

Outline

• Background and motivation• Cost model in ad hoc networks • Cost-based routing scheme• Adaptation to existing routing protocols• Experimental results• Conclusions



Introduction• Wireless networks become increasingly popular

and affordable• Ad hoc mobile wireless networks

– Dynamic and easy deployment– No fixed infrastructure required– Applications

• Emergency disaster relief, battlefields, information gathering, group interaction

• Routing is crucial to the success of ad hoc mobile wireless networks



Routing in Ad Hoc Networks• Select a suitable path between two nodes • Routing challenges in ad hoc networks

– Dynamics, limited resources, environment complexity• Table-driven proactive protocols

– Maintain consistent up-to-date route information of the network with constant updates

– Examples: DSDV, CGSR, WRP• Source-initiated on-demand reactive protocols

– Invoked only when there is a data delivery request but no existing paths– Examples: AODV, DSR, TORA, ABR

• Location-based protocols– Use information about destination location to forward data packets– Examples: LAR, GPSR, SPEED



Ad Hoc Networks Cost Model • Traditional protocols use hop count only as routing

metrics– Unbalanced link bandwidth– Hops distance– Data forwarding is more costly than wired networks

• Observation: traffic variation diminishes as flows aggregate

• More precise cost-based model is desirable– Consolidate all factors– Take advantages of traffic aggregation

• Higher degree of traffic variation in wireless networks



Cost Model• Connection cost depends on the individual flows• Individual flows exhibit statistically similar behavior• Aggregated flow variation is smaller than the sum of all

individual flow variationCu,v(f) = lu,v ( f + k f ½)Cp(f) = {(u,v) p}Cu,v(f) = {(u,v) p} lu,v ( f + k f ½)– Cu,v(f): cost of transmitting flow volume f between nodes u and v– Cp(f): cost of transmitting flow volume f on path p– lu,v: length between nodes u and v– f: total traffic flow load : individual traffic variation parameter– k: constant factor



Cost-based Routing Scheme• Use the ad hoc network cost model to replace

the hop count as the routing metrics• Basic operations

– Cost computation• By the cost model

– Cost update• Per-link incremental cost Cu,v incurred by flow increment

Cu,v = lu,v [ + k (f + )½ - k ½)]

• Whole path incremental cost Cu,v is computed similarlyCp = {(u,v) p} Cu,v = {(u,v) p} lu,v [ + k (f + )½ - k ½)]



Adaptation to Existing Routing Protocols• Proactive Routing Protocols

– Use new routing tables with Cu,v(link state protocols) or Cp(distance vector protocol) on nodes

• Reactive Routing Protocols– Route discovery

• Use Cu,v to determine the optimal among all outgoing links • Forward requests with piggybacked increment cost

information along all paths, and the destination makes the final decision

– Route maintenance• Changes trigger updates to neighbors

• Location-based Routing Protocols– No need to record distance information



Experimental Results• ns-2 simulator with wireless extension

– Varied number of nodes (50 –200)– IEEE 802.11 radio– Modified vs original AODV

• Total cost comparison

AODV-cmod

AODV-orig



Conclusions

• Ad hoc mobile wireless networks present great challenges to traditional routing algorithms

• A cost model for ad hoc mobile wireless network proposed

• Cost-based routing scheme is described – Cost efficient routing– Adaptive to existing routing protocols

november 4, 2003applied research laboratory, washington university in st. louis apoc 2003 wuhan,...

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