Aerial rescue for cellphone networks

Developments in antennas, a previously overlooked area of telecoms technology, could transform the economics of mobile networks reports.

Operators of mobile telephone networks had to pay staggering amounts for licences for so-called third generation (3G) networks. The high cost of these licences raises questions about the financial basis of the whole sector. If the UK government is going to collect £22.5bn for 3G licences, where will the operators find the money for the new infrastructure?

Estimates suggest that the base stations and networks needed to broadcast in these new wavelengths could cost more than £3bn for each network. With that sort of financial headache, operators are warming to ideas on how to keep down the cost of the new infrastructure. This is why there is growing interest in companies that want to do clever things with the antennas at base stations and in mobile handsets.

When a company says it can save more than half the operating costs of 3G licences, the industry takes notice — at least it does now. A few years ago, ArrayComm, based in San Jose, California, had a hard time persuading operators to listen to its pitch. Now, says Arnaud Saffari, one of the company’s founders, ‘we are starting to get considerable momentum behind our often repeated story that efficient use of radio frequencies is a must’.

The company has come up with a technology that it calls IntelliCell, which it claims can connect more users to the base stations at the heart of each cell of the mobile network, thereby reducing capital expenditure by at least a third. IntelliCell means rewriting the rules, claims Saffari, ‘totally modifying the business plan and cutting the time to it takes to break even by half’.

With that sort of saving possible, it is hard to see why antenna technology has attracted so little interest to date. Dr Graham Cooley, chief executive of Antenova, a company set up last year to develop ‘smart’ antennas, points out that all the effort has gone into developing smaller handsets, better displays and batteries with a longer life. But he adds: ‘It is the antenna that makes it a mobile device.’

Now, finally, telecoms engineers are beginning to pay some attention to the bit that makes it all happen. Antennas are finally becoming intelligent.

Antennas get smart

Antenova and ArrayComm are among a small but growing band of companies that hope to bring smart antennas to mobile telecoms. ArrayComm works on base station technology, while Cambridge-based Antenova develops handsets and base station antennas.

Antenova developed out of work at Sheffield University to support earthquake prediction research.

Earthquakes can be detected by looking out for the radio waves they cause. Earthquake researchers Dr Simon Kingsley, in the Department of Electrical and Electronic Engineering at Sheffield, and Dr Steve O’Keefe of Griffith University, Brisbane, used huge antennas and were working on miniaturising them to make radio detectors easier to handle. Kingsley approached a company in the radio tagging business, activeRF, to seek support for further research. The company’s chief executive, Pilgrim Beart, spotted the potential for mobile telecoms and decided to set up Antenova.

Kingsley came on board as Antenova’s chief researcher. Cooley joined from National Power, where he had taken the company’s energy storage technology from a laboratory experiment to a spin-off business, Regenesys.

The heart of Antenova’s technology, which it calls NovaCell, is a tunable antenna. Current handset antennas broadcast the same signal strength in all directions. In Novacell, the antenna scans the area around it to pinpoint the strongest base station. With the strongest station lined up, the handset’s electronics and control software lock on and broadcast only in that direction. ‘The antenna determines the most effective channel and fires the signal in the right direction,’ says Cooley. ‘You are not constantly filling the area with your signal.’ About every second or so, the antenna sweeps the area to check the user has not moved too far and that it is still locked on to the best channel.

The ‘active ingredient’ of the Novacell technology is a material that makes it possible to design antennas about a tenth the size of conventional copper devices. The antenna is small enough to become a part of the handset’s circuit board and could spell the end of the external antenna on mobile devices.

It also offers other advantages. Because the transmission concentrates on the best base station, power is saved, extending battery life — an important consideration for mobile phone users.

‘You can make a quantum step in the efficiency of the battery simply by doing something with the antenna,’ says Cooley, who predicts that the technology can increase talk-time by around a factor of three.

In addition, because the signal is aimed towards a single base station instead of all round, it reduces the exposure of phone users to radio waves. The risk from such exposure may be hypothetical, but anything that reduces consumer concerns is likely to be popular.

Antenova’s approach to steerable antennas also works with base stations. Cooley predicts that it could allow the number of users per station to increase by 400%.

Higher capacity targets

ArrayComm has its sights set higher. It talks of achieving capacity increases between 600 and 2,000%. The company’s IntelliCell technology does this through signal processing and software that ‘focuses’ radio signals from an array of antennas directly on individual handsets rather than throughout a cell.

ArrayComm uses an analogy with human hearing to explain its approach. The brain can process sound signals from our ears to pinpoint someone who is talking as they walk around a room, even when we cannot see the speaker. The company’s ‘adaptive antenna’ systems do the same thing, using antennas instead of ears. The system can use four or more antennas to fine-tune and increase signal information for received and transmitted signals.

A cell with adaptive antennas can pinpoint a mobile device and send signals back in the same direction. The antenna system not only ‘hears’ things 10 or more times louder, it also talks back more loudly and directly.

The idea for IntelliCell’s software and digital signal processing (DSP) circuitry dates back more than 10 years to when the US funded research in this area for military uses. This resulted in a set of algorithms intended to sort out signal from noise in radio signals. The technology wasn’t up to that application, but the arrival of inexpensive DSP chips has made the approach viable for cellular networks.

ArrayComm has been working on its technology for a decade. It made a leap forward when it was brought in to help Japanese telecoms company DDI Pocket Telephone satisfy the rapid rise of its Personal Handyphone System.

DDI put the US business in touch with Japanese electronics company Kyocera. Together they held trials at 30 stations in 1997. The next year Kyocera began to ship IntelliCell base stations. There are now more than 65,000 base stations worldwide, mostly in Japan and the far east. ArrayComm expects US 3G networks to roll out thetechnology next year.

It takes time to persuade the industry to take up a technology such as IntelliCell, which can’t just be bolted on to existing antennas, even though, according to Saffari, such bolt-on approaches achieve capacity increases of just 20 to 50%.

IntelliCell has to be embedded in base stations at the modem level. This makes 3G networks an attractive target market, because infrastructure doesn’t yet exist and the pressure is on to keep down costs.

ArrayComm has also created a version for personal broadband, called iBURST. This brings internet protocol based communications to mobile devices.

The rise of broadband traffic dispels the notion that you don’t have to worry about efficient use of the radio spectrum. Speech takes up next to no bandwidth, but giving mobile customers the same multimedia services they can reach from their desks eats into bandwidth at megabits, rather than kilobits, per second.

Sony is one of a number of big

players that have signed collaborative deals and stumped up cash to accelerate ArrayComm’s development of this technology. The goal is to provide data throughput at more than 40Mbit/s per cell, with individual users connected to the internet at data rates in excess of 1 Mbit/s. ArrayComm claims iBURST can provide a 40 times higher throughput than alternative 3G technologies.

ArrayComm also works with major players on IntelliCell. In February Marconi announced that it is taking an equity stake in the company and will adopt ArrayComm’s technology. ‘Incorporating IntelliCell technology into our products gives us a significant headstart in the race to deliver superior 3G systems,’ said Aldo Olivari, chief executive of Marconi Mobile, at the time of the announcement.’Finally, the demand for efficient use of radio frequencies is there,’ says Saffari.

Indeed, his business cards now carry a message on the back: ‘3G Spectrum — you didn’t pay too much if your network is powered by IntelliCell’. The mobile network operators will be hoping this is more than just marketing hype.

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