June 3, A New Multipath Routing Protocol for Ad Hoc Wireless Networks Amit Gupta and Amit Vyas
EE384Y Project Presentation June 5, Outline Motivation Intuition and Previous Work Problem Statement Analysis Simulations Conclusion
EE384Y Project Presentation June 5, Motivation Ad Hoc Wireless networks Very quickly deployable Less costly than infrastructure networks Applications Internet connectivity in buildings Connecting computers at a conference Video-conferencing Wireless sensor networks Military communications and emergency services
EE384Y Project Presentation June 5, Motivation Interactive Applications place stringent demands on delay requirements (e.g. telnet or multimedia communication) Lower delays might be more important than bandwidth used Can we achieve lower delays by sending same packet over multiple paths ? What is the trade-off between decrease in delays and increase in bandwidth ?
EE384Y Project Presentation June 5, Outline Motivation Intuition and Previous Work Problem Statement Analysis Simulations Conclusion
EE384Y Project Presentation June 5, Intuition Send same packets along multiple paths Lowers end-to-end probability of losses In turn reduces expected number of retransmissions and number of timeouts Hence decreases expected end-to-end delay More relevant for wireless networks They are more lossy than wired networks But increases bandwidth requirements Let us try to quantify this trade-off
EE384Y Project Presentation June 5, Previous Work Old work Dispersity Routing – Maxemchuk (1975) Efficient Dispersal of Information – Rabin (1989) More recently Apostolopoulos (2001) Split a video into multiple streams and send different streams over different paths to achieve better quality Liang, Steinbach, Girod (2001) Real-time voice communication over the internet using packet path diversity. Experimental setup in which they send packets over two paths using a relay server. Also simulated two CBR voice streams via two paths using ns simulator
EE384Y Project Presentation June 5, Outline Motivation Intuition and Previous Work Problem Statement Analysis Simulations Conclusion
EE384Y Project Presentation June 5, Problem Statement But no one has looked at Impact of using extra paths on bandwidth Trade-off between reduction in delay and extra bandwidth used Optimal number of redundant paths Depends on loss probability, time out values, number of hops Application to routing protocols
EE384Y Project Presentation June 5, Problem Statement Outline of Work Analysis of delay-bandwidth tradeoff Study of loss models for wireless networks Impact of various parameters on the optimum choice Study of current Ad Hoc Wireless Routing Protocols Design of a new protocol Simulations using ns-2 network simulator
EE384Y Project Presentation June 5, Outline Motivation Intuition and Previous Work Problem Statement Analysis Simulations Conclusion
EE384Y Project Presentation June 5, Analysis Loss model for wireless networks Nguyen et. al. (1996) Trace-based approach for modeling wireless channel behavior For AT&T WaveLAN, average packet error rate of 2-3 % Improved two-state model (error, error-free) Two & Three segment curves respectively for distribution Konrad et. al (2001) Markov based channel model Algorithm to divide trace into stationary components These models are very complicated and need very specific parameters Simple probability model is good enough for our study Burst losses and outages will only make our results better
EE384Y Project Presentation June 5, Analysis Important parameters Loss probability over a link Timeout for end-to-end retransmission Number of hops Number of paths Additional delay of alternate path(s) Metrics Expected end-to-end delay Expected bandwidth used Delay-bandwidth product
EE384Y Project Presentation June 5, Analysis Variation of number of paths
EE384Y Project Presentation June 5, Analysis Variation of number of paths
EE384Y Project Presentation June 5, Analysis Variation of number of hops
EE384Y Project Presentation June 5, Analysis Variation of number of hops
EE384Y Project Presentation June 5, Analysis Variation of additional delay of alternate paths
EE384Y Project Presentation June 5, Outline Motivation Intuition and Previous Work Problem Statement Analysis Simulations Conclusion
EE384Y Project Presentation June 5, Current Ad Hoc Wireless Routing Protocols Table-Driven Routing Protocols Destination-Sequenced Distance Vector Routing (DSDV) Clusterhead Gateway Switch Routing (CGSR) The Wireless Routing Protocol (WRP) Source-Initiated On-Demand Ad Hoc On-Demand Distance Vector Routing (AODV) Dynamic Source Routing (DSR) Temporally Ordered Routing Algorithm (TORA) Associativity-Based Routing Signal Stability Routing
EE384Y Project Presentation June 5, Simulations To validate the analysis results Used the ns-2 simulator with wireless extensions Modified DSR protocol to allow multiple paths – Dynamic Multipath Source Routing (DMSR) Simulation Setup Interested in study of delay-BW tradeoff for end-to- end error-recovery protocols (e.g. TCP) Effect of number of hops and network load Two scenarios – deterministic 16 nodes and uniform randomly distributed 30 nodes
EE384Y Project Presentation June 5, Simulations Scenario of 16 nodes Relatively low network load
EE384Y Project Presentation June 5, Outline Motivation Intuition and Previous Work Problem Statement Analysis Simulations Conclusion
EE384Y Project Presentation June 5, Conclusion Use of multiple paths for achieving lower expected delays Studied effect of various parameters on the delay- bandwidth trade-off Determined optimal number of redundant paths Implemented scheme as DMSR Wireless Routing Protocol Validated results using simulations
EE384Y Project Presentation June 5, THE END