• Technology
  • The Economist

Wireless Telecoms: Watch This Airspace

Four disruptive technologies are emerging that promise to render not only the next wave of so-called 3G wireless networks irrelevant, but possibly even their 4G successors.

A Relay Race

Proponents of mesh networks also believe that they have found a way around the last-mile problem. At the moment, there are two main ways to provide broadband connections to the home: use either the local cable-TV network or a digital subscriber-line (DSL) from the local telephone company. DSL supercharges ordinary phone lines to enable them to carry data at high speed.

But not every neighbourhood has cable access, and DSL works only for subscribers close to a telephone exchange. Worse, the roll-out of broadband has been held back by obstructive telecoms incumbents, regulatory obstacles and infighting. No wonder the idea of a fixed wireless broadband service, blanketing a neighbourhood with connectivity without the need to lay any cables, seems so seductive.

The mesh-networking approach, which is being pursued by several firms, does this in a particularly clever way. First, the neighbourhood is “seeded” by the installation of a “neighbourhood access point” (NAP) — a radio base-station connected to the Internet via a high-speed connection. Homes and offices within range of this NAP install antennas of their own, enabling them to access the Internet at high speed.

Then comes the clever part. Each of those homes and offices can also act as a relay for other homes and offices beyond the range of the original NAP. As the mesh grows, each node communicates only with its neighbours, which pass Internet traffic back and forth from the NAP. It is thus possible to cover a large area quickly and cheaply. For providing fixed-wireless access, the mesh approach is technically superior to the traditional “point-to-multipoint” radio approach in a number of ways. For one thing, it requires much less power. Rather than using high power to get around obstacles, mesh networks offer multiple paths from one node to another; with systems typically being self-configuring so that, like the Internet, traffic is sent by the quickest route. Also like the Internet, mesh networks are robust and can be scaled up easily.

Another drawback of point-to-multipoint systems, observes Dave Beyer of Nokia’s wireless-routers division, is their need for tall antennas to get above the clutter and maximise their coverage. Unfortunately, they then run into the problem of interference with adjacent cells. Mesh networks, in contrast, can use rooftop antennas, since each node needs only to be able to communicate with its neighbours. Such systems use one-ten-thousandth of the transmission power. That, in turn, means they can use unlicensed spectrum.

A number of firms are now pushing mesh-network technology as the fastest and easiest way to provide broadband Internet access. Following a successful trial in Santa Rosa, California, Nokia’s system, called RoofTop, is being rolled out by more than 50 operators, mainly small Internet service-providers (ISPs). The ISP installs an AirHead unit (Nokia’s name for a NAP) to seed a neighbourhood, and a small, weatherproof pod with an omni-directional antenna is fixed to the outside of each subscriber’s home or office. Each pod costs around $800 — less if produced in large quantities. Vista Broadband, which offers a broadband service using RoofTop technology in Santa Rosa, charges around $200 for installation, and then a monthly fee of $50.

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