wireless mesh network

 

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A wireless mesh network is a mesh network implemented over a wireless network system such as wireless LAN.

Whereas the Internet is mostly a wire-based, cooperative electronic communication infrastructure similar to the international postal agreement, in that messages are mutually delivered and relayed among their separate domains free of charge, mesh is a wireless cooperative communication infrastructure among a massive number of individual wireless transceivers (i.e. a wireless mesh) that all have network routing capabilities.

History

Main article: History of wireless mesh networking

Wireless mesh networking has seen three generations of technology, each incorporating iterative improvements allowing for greater range, reliability, and cost efficiency.

Some early-generation mesh networking products performed poorly in the substantially "multi-hop" (involving many node-to-node connections) environments in which they were deployed. However, more recent generations have seen improvements to this situation.

Network Structure

Architecture

• Infrastructure wireless mesh networks: Mesh routers form an infrastructure for clients.
• Client wireless mesh networks: Client nodes constitute the actual network to perform routing and configuration functionalities
• Hybrid wireless mesh networks: Mesh clients can perform mesh functions with other mesh clients as well as accessing the network through mesh routers.

Management

This type of infrastructure can be decentralized (with no central server) or centrally managed (with a central server), both are relatively inexpensive, and very reliable and resilient, as each node needs 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 neighbors simply find another route. Extra capacity can be installed by simply adding more nodes.

Applications

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.

Operation

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.

Multi-radio mesh

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.

Radio Techniques

• New modulation scheme
  • In order to achieve higher transmission rate, new wideband transmission schemes other than OFDM and UWB are needed.

• Advanced antenna processing
  • Advanced antenna processing including directional, smart and multiple antenna technologies must be further investigated, since their complexity and cost are still too high for wide commercialization.

• Flexible spectrum management
  • Tremendous efforts on research of frequency-agile techniques are required for their practical use.

• media access control
  • Cross-layer research also should be further investigated, so as to best utilize the advanced features provided by the physical layer.

Protocols

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

• DSDV (Destination-Sequenced Distance-Vector Routing)
• AODV (Ad-hoc On Demand Distance Vector)
• B.A.T.M.A.N. (Better Approach To Mobile Adhoc Networking)
• PWRP (Predictive Wireless Routing Protocol)
• DSR (Dynamic Source Routing)
• OLSR (Optimized Link State Routing protocol)
• OORP (OrderOne Routing Protocol) (OrderOne Networks 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

• Mesh networking
• Generations of mesh networks
• IEEE 802.11s
• Smart antenna
• Mobile ad-hoc network
• Wireless ad-hoc network
• Wireless Distribution System
• Wireless LAN
• Peer to peer
• ZigBee
• Ant colony optimization
• ANT (network)
• Wireless community network
• Shared mesh
• Meraki
• CUWiN
• roofnet
• MeshBox
• Switched mesh
• Netsukuku
• TinyOS
• Public Safety Network
• comparison of wireless data standards

References

• Ian F. Akyildiz , Xudong Wang , Weilin Wang, "Wireless mesh networks: a survey", Computer Networks and ISDN Systems, v.47 n.4,p.445-487, 15 March 2005

• Ian. F. Akyildiz and Xudong Wang, "A Survey on Wireless Mesh Networks," IEEE Communications Magazine, vol. 43, no. 9, s23-s30, Sept. 2005

External links

• Wifi Mesh Networking Softwares My Experiments with Wifi Mesh Networks.
• Wayflex First mesh based ISP in Brazil.
• Roofnet.net Mesh network documentation and monitoring for MIT-based roofnet networks
• Analysis of Mesh Architectures Why all mesh products are not created equal.
• What is Third Generation Mesh? Review of three generation of mesh networking architectures.
• Is Multi-radio mesh worthwhile? Cost considerations of multi-radio mesh.

• Moskaluk Wireless Mesh Don Moskaluk Mesh network documentation and monitoring for Locustworlds Open Source AODV
• NetEquality A non-profit building mesh networks for low-income neighborhoods
• IET From hotspots to blankets
• Remesh Brazilian Mesh Project
• Infinet Wireless (WiMAX, MESH Equipment)

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