Introduction to mesh networks

Conventional wireless networks have a central transmitter, often termed a base station, transmitter mast or node. This controls the communications with devices within its range. For example, in a cellular system base stations provide coverage across an area and control the access from mobiles in the vicinity. The central transmitter is often elevated relative to the receivers – transmitters of cellular masts are typically 10–20 m above the ground while mobiles are mostly 1–2 m above ground.

A much discussed alternative is for there not to be a central transmitter. In the most extreme case devices transmit to other devices that relay their message onwards. If, for example, all communications occurred within a shopping mall, it might be quite possible for messages to pass from transmitter to intended recipient via re-transmissions (often termed ‘hops’) from one device to another across the mesh. Alternatively, the message might pass through a mesh in order to reach a point of interconnection with the fixed network (a ‘sink node’). At this point the message would be routed through the fixed network to the recipient in a conventional manner, although the final ‘drop’ to the recipient might be via another wireless mesh network.

Mesh systems potentially bring a number of advantages.

• No need for infrastructure. Without any central transmitters, mesh networks do not require any infrastructure and hence are simpler, cheaper and faster to establish than conventional networks. They can also work where it is not possible to deploy a central infrastructure, perhaps in a war zone or during a civil emergency.

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