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Image showing mesh network layout

Animation showing self healing wireless mesh (enlarge)

Mesh networking is a type of networking wherein each node in the network may act as an independent router, regardless of whether it is connected to another network or not. It allows for continuous connections and reconfiguration around broken or blocked paths by “hopping” from node to node until the destination is reached. A mesh network whose nodes are all connected to each other is a fully connected network. Mesh networks differ from other networks in that the component parts can all connect to each other via multiple hops, and they generally are not mobile. Mesh networks can be seen as one type of ad hoc network. Mobile ad hoc networks (MANET) and mesh networks are therefore closely related, but MANET also have to deal with the problems introduced by the mobility of the nodes. Mesh networks are self-healing: the network can still operate when one node breaks down or a connection goes bad. As a result, the network may typically be very reliable, as there is often more than one path between a source and a destination in the network. Although mostly used in wireless scenarios, this concept is also applicable to wired networks and software interaction. The animation at the right illustrates how wireless mesh networks can self form and self heal. For more animations see History of Wireless Mesh Networking

Wireless mesh networks are the most topical application of mesh architectures. Wireless mesh networks was originally developed for military applications but have undergone significant evolution in the past decade. As the cost of radios plummeted, single radio products evolved to support more radios per mesh node with the additional radios providing specific functions- such as client access, backhaul service or scanning radios for high speed handover in mobility applications. The mesh node design also became more modular - one box could support multiple radio cards - each operating at a different frequency.

Work in this field has been aided by the use of game theory methods to analyze strategies for the allocation of resources and routing of packets.^[1]

[edit] Examples

Building a Rural Wireless Mesh Network: A DIY Guide (PDF)

In early 2007, the US-based firm Meraki launched a mini wireless mesh router.^[2] This is an example of a wireless mesh network (on a claimed speed of up to 50 megabits per second). The 802.11 radio within the Meraki Mini has been optimized for long-distance communication, providing coverage over 250 meters. This is an example of a single-radio mesh network being used within a community as opposed to multi-radio long range mesh networks like Belair^[3] or MeshDynamics^[4] that provide multifunctional infrastructure.

The Naval Postgraduate School, Monterey CA, demonstrated a wireless mesh network for border security.^[5] In a pilot system, aerial cameras kept aloft by balloons relayed real time high resolution video to ground personnel via a mesh network.

An MIT Media Lab project has developed the XO-1 laptop or "OLPC" which is intended for under-privileged schools in developing nations and uses mesh networking (based on the IEEE 802.11s standard) to create a robust and inexpensive infrastructure.^[6] The instantaneous connections made by the laptops are claimed by the project to reduce the need for an external infrastructure such as the Internet to reach all areas, because a connected node could share the connection with nodes nearby. A similar fish concept has also been implemented by Greenpacket with its application called SONbuddy.^[7]

In Cambridge, UK, on the 3rd June 2006, mesh networking was used at the “Strawberry Fair” to run mobile live television, radio and Internet services to an estimated 80,000 people.^[8]

The Champaign-Urbana Community Wireless Network (CUWiN) project is developing mesh networking software based on open source implementations of the Hazy-Sighted Link State Routing Protocol and Expected Transmission Count metric.

SMesh is an 802.11 multi-hop wireless mesh network developed by the Distributed System and Networks Lab at Johns Hopkins University.^[9] A fast handoff scheme allows mobile clients to roam in the network without interruption in connectivity, a feature suitable for real-time applications, such as VoIP.

Many mesh networks operate across multiple radio bands. For example Firetide and Wave Relay mesh networks have the option to communicate node to node on 5.2 GHz or 5.8 GHz, but communicate node to client on 2.4 GHz (802.11). This is accomplished using SDR (Software-Defined radio.)

The SolarMESH project examined the potential of powering 802.11-based mesh networks using solar power and rechargeable batteries.^[10] Legacy 802.11 access points were found to be inadequate due to the requirement that are continuously powered.^[11] The IEEE 802.11s standardization efforts are considering power save options, but solar-powered applications might involve single radio nodes where relay-link power saving will be inapplicable.

Recent standards for wired communications have also incorporated concepts from Mesh Networking. An examples is ITU-T G.hn, a standard that specifies a high-speed (up to 1 Gigabit/s) local area network using existing home wiring (power lines, phone lines and coaxial cables). In noisy environments such as power lines (where signals can be heavily attenuated and corrupted by noise) it's common that mutual visibility between devices in a network is not complete. In those situations, one of the nodes has to act as a relay and forward messages between those nodes that cannot communicate directly, effectively creating a mesh network. In G.hn, relaying is performed at the Data Link Layer.

[edit] See also

Wikimedia Commons has media related to: Mesh network

• OLSR
• B.A.T.M.A.N.
• Open Shortest Path First
• Peer-to-peer
• Game theory in communication networks

[edit] Mesh network applications

• Wireless mesh network
• Distinct radio node deployments of Wireless Mesh Networking
• BioWeb
• Wireless ad hoc network
• Wireless community network
• Mobile ad hoc network (MANET)
• Vehicular ad-hoc network
  • Intelligent Vehicular AdHoc Network

[edit] Mesh network devices

• Open-Mesh
• MeshBox
• Meraki
• MICAz

[edit] Technical challenges

• Wizzy Digital Courier
• Delay-tolerant networking

[edit] References

[edit] External links

• MIT Roofnet A research project at MIT that forms the basis of roofnet / Meraki mesh networks
• WING Project Wireless Mesh Network distribution based on the roofnet source code
• Miners Give a Nod to Nodes Reprint from Mission Critical Magazine on successful deployment of mesh in mines
• DARPA's ITMANET program and the FLoWS Project Investigating Fundamental Performance Limits of MANETS
• Robin Chase discusses Zipcar and Mesh networking Robin Chase talks at the Ted conference about the future of mesh networking and eco-technology
• Mesh Networks Research Group Projects and tutorials' compilation related to the Wireless Mesh Networks