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UK watchdog wants to beef up wifi

Britain’s telecom regulator, Ofcom, is looking at ways to increase the legal range of high-powered wifi equipment to 6.2 miles. If successful, the boost in range could have profound effects for both the consumer and the industry.

Ofcom intends to up the power limits for 2.4Ghz band equipment which could be used to good effect in rural areas where laying cables is uneconomical.

The watchdog issued a consultation which, it says “seeks input” on the effects of increasing the power levels on wifi devices “in order to facilitate new services”. For rural areas, those new services could be as fundamental as internet access.

Power limitations exist in licence exempt spectrum, to minimise the risk of interference but, according to the watchdog, “in rural areas there are likely to be fewer users and hence a lower probability of interference.”

The watchdog is proposing to:

Boost the power of wifi signals

Confining the resulting increase to rural areas only

Working with the industry to ensure minimal signal interference

Niall Murphy, chief technology officer at the UK’s leading wifi wholesaler The Cloud, welcomed Ofcom’s move, which he saw as “typical” of Ofcom’s work in the telecoms arena. “Simply, it means we can send more signals to more people.” He did, however, warn of the consequences if the process is not tightly managed. “In rural areas there should be no problems but… interference is an issue in urban areas and Ofcom will have to ensure issues around interference are managed.”

Mike Roberts, senior analyst with Telecoms.com’s parent, Informa Media and Telecoms believes the changes, if they come, will have a profoundly positive effect on service providers in particular.

He said: “Ofcom’s proposal to increase power limits in the unlicensed 2.4GHz and 5GHz bands could significantly improve the business case for wireless broadband services in these bands, particularly in small-to-medium sized cities and rural areas. For example it would encourage new regional operators to launch to offer symmetric wireless broadband services to businesses that can’t get SDSL.” He added: “There are already a handful of these operators in the UK – for example Telabria uses both the 2.4GHz and 5.8GHz bands to offer wireless broadband services to businesses and consumers in the county of Kent – but higher power limits could lead to the launch of many more regional wireless broadband providers.

An exact timetable for the plan has not been released.

Telecoms.com comment:

Ofcom’s decision to look at relaxing transmitter power restrictions for users of the unlicensed 2.4GHz and 5.8GHz bands may have some interesting consequences for community wireless access schemes in particular. Traditionally, unlicensed spectrum is made available on condition that users take all reasonable precautions to avoid interfering with each other. In the UK, the 2.4GHz Industrial, Scientific and Medical spectrum has been subject to restrictions on transmitter power in order, essentially, to allow it to stay unlicensed.

Wireless LAN technology has always worked in unlicensed spectrum – it would have never succeeded had it been tied to allocated and usually paid-for spectrum – and has various features that help it cope with the possibility of interference. For example, all WLAN clients are programmed to “listen before talk” and negotiate which channel to use with the other party to the connection. Despite this, locations with a high density of uncoordinated WLANs tend to see poor performance due to the inter-network interference.

Increasing the transmitter power of a radio system increases both range and throughput, but not linearly as the signal-to-noise ratio falls with increasing wattage. This is of course another way of saying that greater power means greater interference. This goes double for the position where several networks co-exist. Hence the problem.

In several other countries, notably the USA, this has been considered less of a problem. Therefore, it’s been easier to create large, metro-scale WLANs, at least until interference becomes a problem. In the UK, these are likely to be created to cover rural and remote areas underserved by ADSL. Ofcom, presumably, reasons that these areas are unlikely to have many competing users of unlicensed spectrum.

This news may revive last year’s hype over possible unlicensed use of WiMAX, usually in the 5.8GHz band. 5.8GHz 802.16d WiMAX has yet to achieve much – only one vendor currently offers it – for the good reason that WiMAX is not designed to tolerate co-channel interference. It is possible that 802.16d might work well at 5.8GHz in a sparsely populated setting, but otherwise it will have to be either non-standard WiMAX-like gear, or the older high power WLAN standard 802.11a. This is used quite widely for community wireless applications and is often inaccurately described as “pre-WiMAX”.

Despite its being an 802.11 standard, it does not interoperate with the common 802.11b/g WLAN radios. For example, Intel’s 802.11 products share a common silicon radio, but the 802.11a ones require a different aerial to the b/g devices.

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