Wireless Mesh Networking is Mesh networking implemented over a Wireless LAN.

Networking infrastructure is therefore decentralised and inexpensive, as each node need only transmit as far as the next node. Nodes act as repeaters to transmit data from nearby nodes to peers that are too far away to reach, resulting in a network that can span a large distance, especially over rough or difficult terrain. Mesh networks are also extremely reliable, as each node is connected to several other nodes. If one node drops out of the network, due to hardware failure or any other reason, its neighbours simply find another route. Extra capacity can be installed by simply adding more nodes. Mesh networks may involve either fixed or mobile devices.

The principle is similar to the way packets travel around the Internet - data will hop from one device to another until it reaches a given destination. Dynamic routing capabilities included in each device allow this to happen. To implement such dynamic routing capabilities, each device needs to communicate its routing information to every device it connects with, "almost in real time". Each device then determines what to do with the data it receives - either pass it on to the next device or keep it. The routing algorithm used should attempt to always ensure that the data takes the most appropriate (fastest) route to its destination.

The choice of radio technology for wireless mesh networks is crucial. In a traditional wireless network where laptops connect to a single access point, the more laptops connected the less bandwidth available for each user. This is because the devices share a fixed bandwidth amount. With mesh technology and adaptive radio, devices in a mesh network will only connect with other devices that are in a set range. Like a natural load balancing system the more devices the more bandwidth available, provided that the number of hops in the average communications path is kept low.

To prevent increased hop count from cancelling out the advantages of multiple transceivers, one common type of architecture for a mobile mesh network includes multiple fixed base stations with "cut through" high-bandwidth terrestrial links that will provide gateways to services, the Internet and other fixed base stations. The "cut through" bandwidth of the base station infrastructure must be substantial for the network to operate effectively. However, one feature of wireless mesh networks is that an operator need only deploy a minimal base station infrastructure, and allow the users themselves to extend the network.

Since these networks have the potential to be much cheaper than traditional infrastructure, a number of wireless community network groups are experimenting with wireless mesh networks.

Protocols

There are more than 70 competing schemes for routing packets across mesh networks. Some of these include:

• TORA (Temporally-Ordered Routing Algorithm)
• AODV (Ad-hoc On Demand Distance Vector)
• OLSR (Optimized Link State Routing protocol)
• HSLS (Hazy-Sighted Link State)

A more thorough list can be found at Ad hoc protocol list, and implementations at Ad hoc protocols implementations.

See also

• Mesh networking
• Mobile ad-hoc network
• Wireless Distribution System
• Wireless LAN
• Peer to peer
• ZigBee
• Ant colony optimization

External links

• MIT Roofnet A research project at MIT that provides software
• CUWiN Free Ad-Hoc Open-Source Mesh Software utilizing HSLS
• Kingsbridge Link Wireless OSPF Mesh Routing with Central Admin Tools and Mapping Engine
• Locustworld Open Source Mesh Networking software
• Mobile Mesh Networking News and info on mesh networks
• Info-Site about MESH-Technology (German language)
• A discussion of the scalability problems of wireless meshes, and possible solutions
• The Grid Ad Hoc Networking Project
• Kiyon Wireless Autonomic Networks