Slide 1Unicasting using the Multicast protocol?ODMRP OverviewOn Demand Multicast Routing ProtocolRoute construction in ODMRPKey Differences from Other On-Demand Protocols (e.g., DSR, AODV)Unicast enhancement: Mobility PredictionRoute Selection Criteria at DestinationPerformance EvaluationPacket Delivery RatioODMRP Packet Delivery Ratio as a function of refresh intervalConclusionsThe Number of Total Packets Transmitted per Data Packet DeliveredThe Number of Control Bytes Transmitted per Data Byte Delivered by ODMRP with and without Mobility PredictionExploiting the Unicast Functionality of the On-Demand Multicast Routing ProtocolSung-Ju Lee, William Su, and Mario Gerlahttp://www.cs.ucla.edu/NRL/wirelessWireless Adaptive Mobility LaboratoryComputer Science DepartmentUniversity of CaliforniaLos Angeles, CAUnicasting using the Multicast protocol?Generally not possible, or very inefficientMost of the existing m-cast protocols (eg, AMRoute (Ad-hoc Multicast Routing), CAMP (Core Assisted Mesh Protocol), LAM (Lightweight Adaptive Multicast), etc) run on top of a SEPARATE unicast routing protocolCAMP and LAM in particular, only work with certain underlying unicast protocolEXCEPTIONS:Multicast AODV (Ad-hoc On-demand Distance Vector) uses routes obtained from unicast AODVODMRP (On-Demand Multicast Routing Protocol) can transparently function as both multicast and unicastODMRP OverviewMesh topologyForwarding group conceptOn-demand route constructionSoft state multicast group maintenanceUnicast capabilityMobility predictionOn Demand Multicast Routing ProtocolForwarding Group: All the nodes inside the “bubble” forward the M-cast packets via “restricted” floodingMulticast Tree replaced by Multicast “Mesh” TopologyFlooding redundancy helps overcome displacements and fadingFG nodes selected by tracing shortest paths between M-cast membersFGFGFGFGFGForwarding GroupRoute construction in ODMRPSimilar to other on-demand routing protocolsConsists of a query and a reply phaseA source periodically transmits Join Query packets when it has data to sendJoin Query packets can carry data payload to eliminate route acquisition latencyIntermediate nodes forward the packet and set up path back to the source (backward learning)The destination sends a Join Reply in response to a Join QueryKey Differences from Other On-Demand Protocols (e.g., DSR, AODV)Intermediate nodes can not reply from cacheData payload piggybacked on Join Queries must reach destinationsRoutes replied by destination are more up to dateQuery packets are periodically sent as long as there are data packets to sendFresh routes are continually built and usedRoute refresh interval should be carefully selectedUnicast enhancement: Mobility PredictionMobility prediction can help determine longevity of routes and schedule refresh requestsMobility can be predicted, e.g., in an outdoor environment by means of GPS location information; received power based prediction also possibleJoin Queries are flooded only before predicted route disconnection timeThe scheme adapts refresh interval to mobility patterns and speedsRoute Selection Criteria at DestinationRoute 1 is selected if the delay is the criterionRoute 2 is selected if the longevity is the criterionPerformance EvaluationSimulated in GloMoSim written in PARSECCompared the performance of the following schemes:ODMRPODMRP-MP: ODMRP with mobility predictionWRP (Wireless Routing Protocol): an ad hoc distance vector routing protocol LAR (Location Aided Routing): an on-demand protocol that uses GPS location information50 nodes in 1000 meter X 1000 meter areaFree space propagation model, IEEE 802.11 DCFRandom mobility model Constant bit rate sourcesPacket Delivery RatioODMRP Packet Delivery Ratio as a function of refresh intervalConclusionsODMRP is capable of routing both unicast and multicast data effectivelyMobility prediction enhances ODMRP UnicastTestbed implementation: presented at IEEE ICCCN 2000Multicast work: ACM/Baltzer MONET special issue on multipoint communicationshttp://www.cs.ucla.edu/NRL/wirelessThe Number of Total Packets Transmitted per Data Packet DeliveredThe Number of Control Bytes Transmitted per Data Byte Delivered by ODMRP with and without Mobility
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