Download Basic Concepts and Wireless Mesh Networks Neil Tang 1/21/2009

Wireless Mesh Networks
Neil Tang
1/26/2009
CS541 Advanced Networking
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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
WLAN
Mesh Client
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Wireless
Sensor
Network
Cellular
Network
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Network Architecture
 Infrastructure/Backbone WMNs
 Client WMNs: MANET
 Hybrid WMNs: MANET + Backbone WMN
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Hybrid WMN
EAN
IP Router
Mesh Router
Mesh Router
Mesh Router
IP Network in the
Central Office
IP Router
JAN (WMN Backbone)
Workstation Group
Mesh Router/Gateway
Mesh Router
PBX
Mesh Router
Database Server
Phone
First Responder Vehicle
IAN (MANET)
Monitor
PSCD
(undocked)
Voice Terminal
First Responder Vehicle
Sensor
Wired
Wireless
PAN
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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:
> 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 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.
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