Wireless Mesh Networks Neil Tang 1262009

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Wireless Mesh NetworksNeil Tang1/26/2009
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Outline

• Network Architecture
• Characteristics
• Applications
• Major Concerns
• MAC Layer Challenges
• Network Layer Challenges
• Cross-layer Optimization
• Placement Problems

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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
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Network Architecture

• Infrastructure/Backbone WMNs
• Client WMNs MANET
• Hybrid WMNs MANET Backbone WMN

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Hybrid WMN
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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

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Applications

• Broadband Internet Access
• Emergency Networking
• Community and Neighborhood Networking
• Transportation System
• Surveillance Systems.

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Major Concerns

• Throughput
• Fairness
• QoS
• Scalability
• Compatibility and inter-operability.
• Security

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MAC Layer Challenges

• Channel assignment
• gt Static
• gt 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 algorithms are needed.
• Various physical layers directional antenna,
  cognitive radio

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Network Layer Challenges

• Routing mechanism on-demand vs. proactive
• Routing metric design load balancing and
  intra-flow interference must be addressed.
• End-to-end QoS support intra-flow interference
  must be addressed.
• Multicast/Broadcast Routing

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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.

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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.