The difficulty of ‘last mile' Internet access has been concerning broadband suppliers for almost as long as high-speed Internet technology has existed. While transferring data between major cities via high capacity cabling has long been possible, the far greater numbers of cables required, coupled with the difficulty of laying the cables, has meant it has been cost prohibitive to extend broadband Internet access beyond densely-populated metropolitan areas.

Some suppliers have been touting communication via satellite and even wide-area 802.11b Wi-Fi networks as a possible solution, but ‘line of sight' issues have ruled out both of these technologies in many situations. Telecoms companies in Europe and the US are, therefore, trialling a third way that, paradoxically, improves in quality and availability as more people use it – mesh radio.

Like the Internet itself, mesh radio consists of a series of nodes that can transfer and receive information, passing data from its originating point to its destination via any number of nodes until it finally arrives. So rather than there only being one route for information to reach the end user, the data can take a number of paths.

This has a number of advantages. Since radio signals need not go directly from one point to another but can take a more circuitous path, trees, buildings and other obstacles are no longer a barrier and the end user can still have access to a network, provided they are within sight of another user on the network. As more users join the network, so the number of different routes increases as does the bandwidth and reliability of the network. This particular situation contrasts to other systems where last-mile bandwidth is always being squeezed.

Mesh offers speeds of up to 25Mbps for uploading and downloading, compared to a standard speed of 512Kbps for most consumer DSL (digital subscriber line) connections. It also uses far less power than mobile phone masts, avoiding health worries.

Perhaps most important of all, however, for telecoms companies almost shattered by the costs of 3G licences, mesh radio offers a way to provide cheap broadband access for little up-front expense.

"Mesh radio is predominantly of interest to the industry because it's very economical. The last mile has traditionally been quite difficult to exploit, but you can build the mesh radio network as you acquire customers, and each customer adds to infrastructure. Fundamentally, the network is driven by revenue not by up-front investment," argues Viri Patel, VP of marketing at UK-based Radiant Networks, a supplier of Internet access technology.

Radiant's system uses ATM (asynchronous transfer mode) rather than standard TCP/IP (transmission control protocol/Internet protocol) to transfer data from node to node. This, it argues, both solves bandwidth problems and allows traffic to rejoin the cabled network, which uses the same system, at any time. But other companies – notably Caly Networks in the US – are using TCP/IP to ensure complete compatibility and to take advantage of the lower costs brought about by the higher availability of TCP/IP-based networking systems.

In Europe, though, it is Radiant's system that has received most interest. Energis and BT in the UK, Star 21 in Germany, Banda 26 in Spain and FirstMark Communications in France are all piloting the technology. BT spokesman David Orr says that his company, which has a six month technology trial underway in Cardiff, is looking at mesh to get broadband to semi-rural and urban areas where DSL is not available.

The 28GHz to 40GHz spectrum in which most mesh systems operate is licensed, but few companies showed an interest in those licences when governments ran the auctions for them soon after the 3G auctions in 2000. However, with mesh also offering the bandwidth needed for digital television, that could soon change. Governments, keen to sell off analogue television's portion of the spectrum, surmise that mesh could provide the means to offer both broadband and digital television through to all their citizens for an acceptable price.