Scalable Team Multicast in Wireless Ad hoc networks Exploiting Coordinated Motion Mario Gerla University of California, Los Angeles

Introduction team-oriented Many team-oriented operations in MANET scenarios Search and rescue, disaster relief operation, battlefields Each team tends to move together (affinity team model)  a chosen node (e.g., landmark) can represent a team Often, all nodes or none in a team join a multicast group Affinity team model simplifies mobility handling, and thus allows a scalable multicast protocol design LANMAR (Landmark ad hoc routing protocol) works well with affinity team model

Introduction (2) team multicast, M- LANMAR Proposed idea, two-tier team multicast, called M- LANMAR Unicast tunneling from the sources to the representative of each subscribed team Flooding within a team Advantages of M-LANMAR High reliability via unicast tunneling and flooding Easy to manage the large networks based on motion affinity model

LANMAR (Landmark Ad Hoc Routing Protocol) – Background Proactive Routing Efficient handling affinity team model Using the notion of landmarks to keep track of logical subnets (teams) Using two routing schemes A local proactive routing: within a limited scope, nodes exchange their routing table each other A long haul distance vector routing: a landmark of each subnet is propagated to the whole network Routing Tables Local routing table Landmark table

LANMAR-Example Logical Subnet Landmark node1 node2 LM1 LM2 LM3 Landmark Table of node1 (subnet_addr, lm_addr, nextHop, …) Node3 (src) node3LM3subnetAddr3 node3LM2subnetAddr2 node2LM1subnetAddr1 Local Routing Table of node1 (destAddr, nextHop, …) … Node3 Node2 dest Long haul routing local routing

M-LANMAR(Multicast-enabled LANMAR) Extension of LANMAR Proactive scheme Supporting both unicast and multicast routing with very low extra overhead Scalable as the network size and number of groups increase Join MC group: advertising by piggybacking subscribed multicast groups IDs to landmark broadcast packets Leave MC group: simply not advertising/timeout The sources can find joined teams in their landmark table

Source node LM1 LM2 LM3 Subscribed Teams LM4 Tunneling Flooding Scope = 2 (MC1) MC1 node3LM2 subnetAddr3 node3LM4 subnetAddr2 node2LM1subnetAddr1 Landmark table of source node …

Simulation Compared with ODMRP (On Demand Multicast Routing Protocol) Flooding Environments QualNet 2.9 Each source generates data in a CBR fashion Transmission range: 376m, bandwidth 2Mbits Network size: 6000 x 6000 m 2 Nodes: 1000 nodes into 36 teams Mobility: 2 m/s with 10 seconds pause time Following “Reference Point Group Mobility” Packet size: 512 bytes

Simulation Results – Static Network (1000 nodes, 3teams for each group, 1pkts/sec)  As the number of multicast groups increases ODMRP suffers from large control overhead and collisions M-LANMAR achieves high delivery ratio (by unicast tunneling and flooding) Number of MC Groups(#) Delivery Ratio Normalized CTRL OH

Simulation Results – Mobile Network (1000 nodes, 3teams for each group, 2m/s, 10p) 4pkts/sec ODMRP M-LANMAR FLOOD 1pkt/sec ODMRP M-LANMAR FLOOD

Simulation Results – Mobile Network (1000 nodes, 3teams for each group, 2m/s, 10p) (2) As the number of multicast groups increases With small number of groups, ODMRP outperforms M-LANMAR because of its mesh-based multicast structure (redundant paths); M-LANMAR potentially experiences many link breakages With large number of groups, flooding suffers due to heavy overhead With high offered load (right), M-LANMAR outperforms ODMRP (ODMRP suffers from heavy redundant forwarding)

Reliable Multicast Support Reliable Adaptive Lightweight Multicast (RALM) Targeting general multicast protocols NACK-Oriented mechanism Rate-based congestion control Send-and-wait mechanism (freeze the sender’s buffer upon receiving a NACK); congestion handling Round-robin recovery Sources recover the lost pkts for each NACKER one at a time in a round-robin fashion Prevent ACK implosion Combining with M-LANMAR Only landmarks (say representatives) send feedback (e.g. NACK/ACK) to the source Prevents unnecessary feedback implosion

Simulation Results with RALM (1000 nodes, 3teams for each group, 2m/s, 10p, 5 multicast groups) –Delivery ratio Same parameters to the mobile network experiment Increase the offered load (number of pkts/sec) ODMRP suffers from feedback implosion

Simulation Results with RALM (1000 nodes, 3teams for each group, 2m/s, 10p, 5 multicast groups) –Throughput

Discussions Possible extensions of M-LANMAR Efficient resource discovery via content based multicast Use existing MANET multicast protocols to multicast a packet to all landmarks Scalable as the number of teams increases Provide a congestion controlled reliable transport layer like TCP between the sources and the landmarks

Conclusion Propose a new multicast paradigm Team multicast Design M-LANMAR as an example of team multicast Study the performance of M-LANMAR compared with ODMRP and FLOOD Flat multicast has scalability limitations M-LANMAR provides an efficient platform for a reliable and congestion controlled multicast protocol (e.g., TCP) Apply a reliable transport protocol, RALM over M- LANMAR and ODMRP M-LANMAR is an efficient platform for a reliable multicast protocol

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