The A to Z of wireless

M is for Mesh networks

A mesh network is a network made up of a series of nodes (small radio transmitters) that route data to each other and to network users through 802.11 wi-fi standards.

A core advantage of such a network is resilience: if one node fails the others pick up the slack as data hops dynamically from node to node, thereby bypassing any breaks, until the destination is reached. Mesh networks are also self-organising so new nodes are automatically assimilated into the collective, as it were.

While mesh networks can be wired or wireless, the latter type of mesh is useful for building out large areas of connectivity - say in a city where meshes can be used to link up existing wi-fi hotspots and fill in connectivity notspots. London's Square Mile has its own mesh network - launched in 2007 - consisting of 127 nodes built into lampposts and the like.

Wireless mesh networks can also be a less expensive way of delivering connectivity to communities in the developing world than wired networks as they avoid the need to install fixed-line infrastructure.

The mesh component also means linked machines share an internet connection - a useful feature in regions where connectivity is scarce. The responsibility for upkeep and maintenance of network infrastructure is also shared, avoiding any single point of failure.

Nicholas Negroponte's grand One Laptop Per Child (OLPC) plan to put netbooks into the hands of children in developing nations had high hopes for wireless mesh networking.

The XO machines made by the OLPC come with built-in wi-fi antennas designed to automatically create a mesh network with other XOs within a distance of around a third of a mile.

However the mesh networking component of the XOs has not always lived up to the original 'out of the box' connectivity vision. Speaking in an interview with silicon.com last year, David Cavallo, chief learning architect for the OLPC, said there had been problems getting the networks up and running - including dealing with large numbers of XOs in the bigger schools.

Future uses of ad hoc mesh networks could include connected cars which are able to inform each other of upcoming hazards or traffic jams.

Click here to read silicon.com's Cheat Sheet on wireless mesh networking.

XO laptops being used on a women's mountaineering expedition to Everest (Photo credit: One Laptop Per Child via Flickr.com under the following Creative Commons licence)