Wireless mesh network

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Wireless mesh networking is mesh networking implemented over a Wireless LAN.

This type of Internet infrastructure is decentralized, relatively inexpensive, and very reliable and resilient, 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 large distances, 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 solutions are as diverse as communications in difficult environments such as emergency situations, tunnels and oil rigs to battlefield surveillance and high speed mobile video applications on board public transport or real time racing car telemetry.

The principle is similar to the way packets travel around the wired 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, each laptop has to share a fixed pool of bandwidth. With mesh technology and adaptive radio, devices in a mesh network will only connect with other devices that are in a set range. The advantage is that, like a natural load balancing system, the more devices the more bandwidth becomes 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, wired parts of 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 this wireless Internet infrastructure has the potential to be much cheaper than the traditional type, many wireless community network groups are already creating wireless mesh networks.

Protocols

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

  • AODV (Ad-hoc On Demand Distance Vector)
  • PWRP (Predictive Wireless Routing Protocol)
  • DSR (Dynamic Source Routing)
  • OLSR (Optimized Link State Routing protocol)
  • TORA (Temporally-Ordered Routing Algorithm)
  • HSLS (Hazy-Sighted Link State)

The IEEE is developing a set of standards under the title 802.11s to define an architecture and protocol for ESS Mesh Networking.

A more thorough list can be found at Ad hoc routing protocol list.

See also

External links

  • LocustWorld - LocustWorld free open-source MeshAP software
  • OLSR Experiment - Wireless Mesh Networking project in Germany
  • MCG-Mesh A research project at RWTH Aachen University, Germany
  • CRN Cisco acquires Airespace and joins wireless mesh networking forefront
  • MIT Roofnet A research project at MIT that provides software
  • CUWiN - The Champaign-Urbana Community Wireless Network, a major coalition of wireless researchers, companies, and non-profits all creating free open source mesh wireless software.
  • Netsukuku - A mesh network or a p2p net system that generates and sustains itself autonomously.
  • [1]- Toronto Hydro Telecom Selects Siemens for Deployment of Canada´s Largest WI-FI Zone
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