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Wireless Mesh Networks Neil Tang 1/26/2009

Wireless Mesh Networks Neil Tang 1/26/2009. Outline. Network Architecture Characteristics Applications Major Concerns MAC Layer Challenges Network Layer Challenges Cross-layer Optimization Placement Problems. Wireless Mesh Network (WMN). Internet. Mesh Router/Gateway. Mesh Router.

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Wireless Mesh Networks Neil Tang 1/26/2009

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  1. Wireless Mesh NetworksNeil Tang1/26/2009 CS541 Advanced Networking

  2. Outline • Network Architecture • Characteristics • Applications • Major Concerns • MAC Layer Challenges • Network Layer Challenges • Cross-layer Optimization • Placement Problems CS541 Advanced Networking

  3. Wireless Mesh Network (WMN) Internet Mesh Router/Gateway Mesh Router Mesh Router Mesh Router/Gateway Wireless Mesh Backbone Mesh Router Mesh Router/Gateway Mesh Router/Gateway Cellular Network WLAN Wireless Sensor Network Mesh Client CS541 Advanced Networking

  4. Network Architecture • Infrastructure/Backbone WMNs • Client WMNs: MANET • Hybrid WMNs: MANET + Backbone WMN CS541 Advanced Networking

  5. Hybrid WMN CS541 Advanced Networking

  6. Characteristics • Multihop wireless network. • Stationary mesh routers, and stationary/mobile mesh clients. • Mesh routers are connected with AC power but mesh clients are usually powered by battery. • Multi-radio and multi-channel • Various physical layer techniques, e.g., OFDM/OFDMA, directional antenna, cognitive radio CS541 Advanced Networking

  7. Applications • Broadband Internet Access • Emergency Networking • Community and Neighborhood Networking • Transportation System • Surveillance Systems. CS541 Advanced Networking

  8. Major Concerns • Throughput • Fairness • QoS • Scalability • Compatibility and inter-operability. • Security CS541 Advanced Networking

  9. MAC Layer Challenges • Channel assignment: > Static > Dynamic • Scheduling-based MAC (TDMA) Design: Find a collision-free transmission schedule with the objective of improving throughput, fairness, QoS. • Scalability: distributed channel assignment and scheduling algorithmsare needed. • Various physical layers: directional antenna, cognitive radio CS541 Advanced Networking

  10. Network Layer Challenges • Routing mechanism: on-demand vs. proactive • Routing metric design: load balancing andintra-flow interference must be addressed. • End-to-end QoS support: intra-flow interference must be addressed. • Multicast/Broadcast Routing CS541 Advanced Networking

  11. Cross-layer Optimization Under dynamic traffic model: • Static channel assignment + joint routing and scheduling • Joint routing, scheduling and channel assignment Under static traffic model: • Static channel assignment + joint congestion control, routing and scheduling • Joint congestion control, scheduling and channel assignment • Joint congestion control, scheduling, routing and channel assignment • Joint congestion control, scheduling, routing, power control and channel assignment If using 802.11MAC, no need to consider scheduling. CS541 Advanced Networking

  12. Placement Problems • Mesh router (access point placement): place minimum number of mesh router to cover a region or a set of points (houses) such as the traffic demands can be satisfied. • Gateway placement: select minimum number of mesh routers as gateway such as the traffic demands can be satisfied. CS541 Advanced Networking

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