CS541 Advanced Networking 1

Wireless Mesh NetworksWireless Mesh Networks

Neil TangNeil Tang1/26/20091/26/2009

CS541 Advanced Networking 2

OutlineOutline

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)Wireless Mesh Network (WMN)

Mesh Client

Mesh Router

Mesh Router/Gateway

Mesh Router/Gateway

WLAN Wireless Sensor Network

Cellular Network

Internet

Mesh Router/Gateway

Mesh Router/Gateway

Mesh Router

Wireless Mesh Backbone

Mesh Router

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Network ArchitectureNetwork Architecture

Infrastructure/Backbone WMNs

Client WMNs: MANET

Hybrid WMNs: MANET + Backbone WMN

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Hybrid WMNHybrid WMN

JAN (WMN Backbone)

EAN

Mesh Router

Mesh Router

Mesh Router

Mesh Router Mesh Router

Mesh Router/Gateway

IAN (MANET)

First Responder Vehicle

First Responder Vehicle

PSCD (undocked)

Database Server

IP Router

Workstation Group

IP Network in the Central Office

IP Router

Monitor

Voice Terminal

Sensor

PAN

Wired

Wireless

PBX

Phone

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CharacteristicsCharacteristics

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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ApplicationsApplications

Broadband Internet Access

Emergency Networking

Community and Neighborhood Networking

Transportation System

Surveillance Systems.

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Major ConcernsMajor Concerns

Throughput

Fairness

QoS

Scalability

Compatibility and inter-operability.

Security

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MAC Layer ChallengesMAC 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 algorithms are needed.

Various physical layers: directional antenna, cognitive radio

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Network Layer ChallengesNetwork 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 OptimizationCross-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 ProblemsPlacement 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.