Multicast Algorithms for Multi- Channel Wireless Mesh Networks Guokai Zeng, Bo Wang, Yong Ding, Li Xiao, Matt Mutka Department of Computer Science and Engineering Michigan State University IEEE International Conference on Network Protocols (ICNP 2007)

Outline  Introduction  System Model  Multicast Algorithms  Simulation  Conclusion

Introduction  Mesh networks are characterized by the use of multiple channels and multiple interfaces  There are three types of nodes in wireless mesh networks Gateways (access points)  Enable the integration of WMNs with various other networks, including the Internet Mesh routers  Minimal mobility and form the mesh backbone  Equipped with multiple wireless interfaces Mesh clients  End users, such as laptops and PDAs  Within one-hop of the mesh routers

Introduction  Video On Demand poses a big challenge for the limited bandwidth of WMNs  However, traditional multicast protocols assume that each node is equipped with one interface

Goals  To improve the system throughput by allowing simultaneous close-by transmissions with multi-channel and multi-interface  To assign all the available channels to the interfaces instead of just the non-overlapping channels

System Model  Partial Overlap  Assumptions

System Model_ Partial Overlap  Some researches assume that b/g only use three non-overlapping channels: 1, 6, and 11 binary interference model R R’ Assume R’ = 2R Channel 1 Channel 6

System Model_ Partial Overlap R R’ Channel 1 Channel 6 R R’ Channel 5 R δ t is Interference Factor, channel separation of two links is t Ex: δ 0 =2, δ 6 =0 Interference range = R * δ t

System Model_ Assumptions  The following assumptions for Mesh routers Limited mobility Don’t rely on battery power Equipped 2 interface Multi-channel

Multicast Algorithms  Level Channel Assignment Algorithm (LCA)  Multi-Channel Multicast Algorithm Multicast Structure Construction  Broadcast Structure  Multicast Structure Channel Assignment  Ascending Channel Allocation  Heuristic Channel Assignment Failure Recovery

Multicast Algorithms_ Level Channel Assignment Algorithm (LCA) s ab ce f h i j s ab ce f h i j Level 0 Level 1 Level 2 Level 3 d g d g Network Topology Multicast Tree

Multicast Algorithms  The goals of Multi-Channel Multicast Algorithm Minimizing the delay Minimal number of relay nodes  Broadcast Structure  Multicast Structure

Multicast Algorithms  Level Channel Assignment Algorithm (LCA)  Multi-Channel Multicast Algorithm Multicast Structure Construction  Broadcast Structure  Multicast Structure Channel Assignment  Ascending Channel Allocation  Heuristic Channel Assignment Failure Recovery

Multicast Algorithms_ Broadcast Structure s ab ce f h i j s Level 0 Level 1 Level 2 Level 3 d g Network Topology Tree Mesh BFS hi j ab c d e fg

Broadcast Structure_ Find Relay node Relay node Level i+1 1.Find minimal number of parents c d b a {1,5,7} 2.Find the maximal number of children From {a,c,d},and their parent of set{1,5,7} is {a,c,d} a 123 aa cd c 45 c d 67 d

Multicast Algorithms_ Broadcast Structure s Broadcast Tree hi j ab c d e fg Relay node a d e c Top-Down

Multicast Algorithms  Level Channel Assignment Algorithm (LCA)  Multi-Channel Multicast Algorithm Multicast Structure Construction  Broadcast Structure  Multicast Structure Channel Assignment  Ascending Channel Allocation  Heuristic Channel Assignment Failure Recovery

Multicast Algorithms_ Multicast Structure s Multicast Tree hi j ab c d e fg Relay node b c Bottom-up a Multicast member node

Multicast Algorithms  Level Channel Assignment Algorithm (LCA)  Multi-Channel Multicast Algorithm Multicast Structure Construction  Broadcast Structure  Multicast Structure Channel Assignment  Ascending Channel Allocation  Heuristic Channel Assignment Failure Recovery

Multicast Algorithms_ Ascending Channel Allocation s i j ab c d e f g Receive-interface (RI)Send-interface (SI) Available Channel = 3 channel = 0 channel = ( channel + 1 ) mod 3

Multicast Algorithms  Level Channel Assignment Algorithm (LCA)  Multi-Channel Multicast Algorithm Multicast Structure Construction  Broadcast Structure  Multicast Structure Channel Assignment  Ascending Channel Allocation  Heuristic Channel Assignment Failure Recovery

Multicast Algorithms_ Heuristic Channel Assignment indicates the interference range of sender u of one link with respect to sender v of another link channel uv R R

Multicast Algorithms  Level Channel Assignment Algorithm (LCA)  Multi-Channel Multicast Algorithm Multicast Structure Construction  Broadcast Structure  Multicast Structure Channel Assignment  Ascending Channel Allocation  Heuristic Channel Assignment Failure Recovery

Multicast Algorithms_ Failure Recovery Tree construction Node 5 break down 1.Find Relay node 2.Random select Relay node Recovery

Simulation_ Parameters  NS2 simulator (version 2.29)  900m * 900m Flat area  Transmission range is 250m  Carrier sensing range is 550m  Default IEEE MAC  Packet size is set to be 512 bytes.

Simulation_ Impact of Network Size

Simulation_ Impact of Number of Available Channels

Simulation_ impact of Number of Transmission Rate

Simulation_ Delay Comparison

Simulation_ Partially Overlapping Channel Test

Conclusion  Two multicast algorithms, LCA and MCM, are proposed by using multi-channel and multi-interface  The performance evaluation shows that algorithms and channel assignment can further improve throughput and reduce delay

Thank You~