Why you should care about GPS in mobiles

You are probably familiar with the Global Positioning System, or GPS, as the system that tries to tell drivers the shortest way from A to B, or tracks goods in transit. However, although people in North America and the Far East have had GPS in their mobile phones for years now, such devices are still rare in Europe.

This situation may be about to change, though, as manufacturers and operators finally put their heads together to make it happen.

What is GPS?
Developed by the US military, GPS (officially called the Navstar GPS) involves a series of two dozen or so satellites orbiting the earth. A receiver on the ground will then communicate with one or more of these satellites, receiving their locations at precise times to work out its own location.

Isn't there a European alternative?
There will be: Galileo. It should be up and running by the end of next year, and companies such as Cambridge Silicon Research are already working on chips that can talk to both GPS and Galileo. The Russians are also dusting off their old Glonass system for 2010, and some suggest China could try extending its Beidou satellite constellation.

For now, let's take "GPS" to mean global navigation satellite systems in general.

Why would I want a GPS receiver in my phone?
For the same reason you would have one in a car, for one thing — as a guide. Think of it as sat-nav for walking. GPS-enabled handsets also open up all sorts of possibilities for advertisers, who would love to have you walking past a store and seeing their deals popping up on your screen. The UK is one of the most mapped nations on Earth, yet we don't make much use of that information.

The system has many advantages for companies managing field workers, or parents tracking their kids (see below).

Can't all that be done already, through mobile phone signals?
Up to a point. Triangulation (establishing your location by measuring the distance between you and three points of known location) does work fairly well with mobile phone masts by measuring time and signal strength. GPS is a lot more accurate though, pinpointing location to within five metres compared to the tens of metres you get with GSM triangulation.

However, GPS can be the worse option in an urban situation, as it does not work indoors. Cities also have a high density of mobile cells, a situation which favours mast triangulation.

Why has it not taken off here?
One reason is the cost of the chips, currently around £3-£5. This will probably change over time. Cambridge Silicon Radio, for example, now claims that adding GPS to a phone could cost just 50p if the technology is integrated into one of its Bluetooth chips. GPS also requires a rather awkward (by European fashion-phone standards) antenna, and chews up both bandwidth and batteries.

The big barrier, however, is a willingness on the part of the operators to see GPS integrated into their handsets. Demand for location-based services is far from proven, and a killer application still needs to emerge which will turn such services into guaranteed cash. Of course, that won't happen unless the necessary technology is available, making this a classic chicken-and-egg scenario.

Why have the Americans and Japanese legislated for having GPS in phones?
So that the emergency services can trace anyone calling them from a mobile phone, who might not know where they are. Fears of kidnapping have also led some parents to track their children using GPS.

Needless to say, this all raises interesting questions about privacy, although carrying a phone already means you can be tracked to some degree of accuracy.

When might Europe's attitude to GPS in phones change?
Possibly quite soon. The UK's National Physics Laboratory is gathering the key players to a meeting on Thursday to debate the problem, and we'll be there to cover the event.