New research may give major boost to mobile phone data systems

Mobile phone companies are busy promoting WAP services but few consumers are heeding the call. The mobile's small screen is not user-friendly and carries too little data to provide an attractive service. Getting the data to the mobile quickly is also a problem.

Improvements in the look of mobile phone data screens are not too far away, however, given very active research programmes that seek to get more information more quickly down a radio signal.

News from the US should encourage service providers seeking to convince mobile users that mobile data systems are worth having. A team involving researchers from Lucent Technologies in Murray Hill, New Jersey, and from Harvard University, Massachusetts, have found a way to treble the capacity of wireless radio communications.

More capacity in a single radio signal means more information, and this in turn means a better-looking screen that provides more data, perhaps even in colour. The researchers describe their findings this month in the journal Nature.

There is a ready-made market for improved services here, given that six out of 10 people in the Republic carry a mobile phone - a higher market penetration than many countries, including the US. Continued growth, however, will depend on finding new applications for the public to buy into. The mobile industry has already recognised that data services, particularly e-mail and Internet links, are the answer to market growth, according to Dr Henry L Bertoni of the Department of Electrical and Computer Engineering at the Polytechnic University, Brooklyn, New York. Also writing in Nature, Dr Bertoni points out, however, that existing wireless connections suffer from today's low rate of data transmission, resulting in unacceptable delays when downloading a Web page.

WAP (wireless application protocol) was developed by a consortium of large companies as a way to overcome the data transfer speed issue. It involves reducing the content of datarich Web pages so they are more in keeping with the low data rates of mobile networks.

The Lucent/Harvard approach has found another way around this, however, with the discovery that there is actually more carrying capacity in any given frequency than expected. Traditionally, radio communications relied on one channel per frequency, even though each radio wave actually has two possible information carrying components - the wave's electrical component and its associated magnetic component.

The research is all rather exotic but is simple enough to grasp if one thinks back to secondary school science. A wire carrying an electric current also has a magnetic field associated with it. A radio wave is no different, as the accompanying illustration shows, with the wave's electric field and its magnetic field lying perpendicular to one another.

This means that each wave actually has two distinct information-carrying channels, if the receiver catching the radio wave knows how to read them. The Lucent/Harvard team took this one step further by trebling the two channels to six, all stuffed down a single frequency.

They managed this by using the radio signal scattering that is typical in built-up urban settings and in indoor radio signal systems. Scattering has, in the past, been a problem for mobile phones, with incoming signals bouncing off nearby objects and causing interference. This problem has been ironed out, but what was once a nuisance has been turned to advantage by the Lucent/Harvard team. With scattering, the initial radio signal reaches the receiver from any one of many routes, some direct line-of-sight, some by bouncing the radio waves billiard ball-like off nearby buildings, as shown in the accompanying illustration. Instead of one antenna to send their signal, the team used three antennae, each slightly out of line with one another. This improvement is made possible by the unique "echo signature" of each of the transmitting antennae, which can be detected and interpreted by the receiving system. The benefit would not be available if there was no scattering.

The signal, in turn, needs three receiving antennae that can decode and reproduce the original signal. The net result is that the researchers boosted the amount of information they could send by a factor of three. "The extra capacity arises because there are six distinguishable electric and magnetic states of polarisation at a given point, rather than two as is usually assumed," the researchers concluded.

To prove their point, they broadcast across a large room the painting A toute epreuve by Spanish artist Joan Miro. They split it into three distinct colour signals and sent it over a single frequency, then reassembled it at a receiver, reconstituting a perfect picture. If they can do it with art, they can do it with a Web page, with full colour and information as well. It may take a little time to reach the market but ideas that work travel fast.