Jan/Feb 2004

Instead of using GPS to track vehicles and people, you can now do it just by tracking mobile phones. But could GSM tracking really replace GPS? Sharon Clancy looks in detail at the pros and cons of the two approaches

As recently as a year ago, tracking by GSM mobile phone cells was a still fledgling technology. Even mobile phone network operators themselves were apparently cautious about its appeal. However, it has quickly entered the mainstream, driven mainly by location-based service (LBS) providers, who predict huge demand from consumers for services such as "show me the nearest cashpoint". Now those companies are targeting corporate users, and are having such success that in some market sectors traditional GPS tracking systems face a serious challenge.

Just to recap, in case there are still any newcomers out there to the exciting world of people and asset tracking, "traditional" tracking relies on signals transmitted by the satellites of the US Government's GPS (Global Positioning System) to work out where the tracked item is. So it requires two main components: an on-board GPS receiver, and some form of communication device to report the position back to base.

Confusingly, this device might well be a GSM phone or data modem. GSM, of course, stands for Global System for Mobiles, which is basically the standard technology for current digital mobile phones. GSM devices are the standard method for reporting information on vehicle location wirelessly, although when used with GPS tracking equipment they are merely transmitting information, not working out their position.

 

GSM tracking, by contrast, is quite different. It takes advantage of the fact that the mobile phone network operators already track the location of ordinary mobile phones all the time they are switched on. They do this as a matter of course, so that their networks know which "cell" any given mobile is in, and can feed transmissions to and from it. So it was a logical step for them to package the positioning information into a commercial product, which is now offered through a growing number of third-party suppliers.

So does it really matter whether you use GPS or GSM to track your vehicles or mobile workers? Certainly a lot of noise is currently being generated by the GSM tracking providers. If you believe the hype, you could be forgiven for thinking that GPS systems are old hat, and unnecessarily complex in today's wireless world. However, GPS still confers some advantages, especially if your primary need is to track vehicles rather than mobile workers.

Pros and cons

When it comes to cost, there are pros and cons to both technologies. GSM tracking has the advantage of low set-up costs and fast roll-out. It works with any current mobile phone via its GSM SIM card. So long as the user gives you permission, you can track existing mobile phones simply by registering them with your chosen LBS provider.

GPS is more expensive to install; a GPS-GSM telematics unit typically costs anything up to around £800. They are often hard-wired into the vehicle, so drivers cannot be tracked away from the vehicle. You simply have to ask.

On the plus side, though, GPS is passive; the receiver continually updates it position relative to the satellites, so it always knows where it is. By contrast, one obvious drawback of GSM tracking is that if the mobile phone or GSM modem is turned off, you will not be able to locate it. Worse, as even GSM tracking specialist Verilocation warns, the networks currently still tend to charge for each request for a location fix, even if they cannot find the phone. Most networks will report "unable to locate", although phones on the Vodafone network will show their last known position.

With GPS, the traditional route has been that the user pays for the hardware, connection and applications separately. LBS tracking is structured differently; the user pays for the phone, while the services are provided by the network operator or applications provider.

Accuracy

The advantage of the GPS system is that it is reliable and accurate regardless of where the vehicle is in the UK (or, for that matter, anywhere on the globe). The orbiting GPS satellites continually transmit time and position data. This is picked by the GPS receiver on the vehicle, which then calculates its exact latitude and longitude. In theory this will be accurate to 100 metres at worst, and in most cases it will be much better than this.

The GSM modem used to transmit the GPS-derived data back to base has the added benefit of allowing SMS or other forms of data message to be passed between the driver and transport office via a suitable in-cab interface.

That's not the whole picture however. In urban areas, the GPS signal can be blocked by tall buildings in a phenomenon known as the "urban canyon syndrome". To get a position fix requires a line of sight to at least three satellites, and the signals can bounce off buildings, reducing accuracy.

GSM tracking relies on Cell Identification, or Cell-ID - the means by which the phone networks track individual phones form cell to cell. Positional accuracy relies on the number of mobile masts in the area, so it can be accurate to 100 metres or as imprecise as within 10km or more.

As we explain later (see panel, page 18), technology is being developed to improve Cell-ID accuracy, but in the meantime the GSM tracking specialists tend to side-step this problem by maintaining that as users are more likely to require location data in an urban environment anyway, GSM tracking can compete on accuracy with GPS - and may even beat it where GPS signals are weak.

Another argument is that position accuracy is no longer the top priority for some companies. "In the past, general positioning accuracy came top of the list and GPS won hands-down, but things are changing," says Colin Bates, chief technology officer for Mobile Commerce. "Companies are now looking for a technology that is simple to deploy, offers good value for money, and adds the best value to location-enabled applications.

"LBS suddenly comes to the forefront, because these demands do not depend on absolute accuracy. The technology must be readily available and easily integrated with existingservices, which immediately puts LBS in the lead."

Graham Church, MapAmobile's marketing manager, agrees. "With GPS in towns, you sometimes get a message saying 'no position,' or even a false signal. Knowing the position within one or two miles gives sufficient accuracy for many logistics companies." (See Product Evaluation of MapAmobile's service on page 23).

But LBS location is not infallible either. Apart from switched-off phones, location requests sometimes fail because numbers have been transferred from one network to another - commonly called "porting". Bryan Stockwell, business development manager for Mobile Commerce, says this is currently the most common reason for a location request failing. "There is intense price competition between network operators, and businesses do change their network to benefit from the cost savings."

To overcome the problem, Mobile Commerce has upgraded its location gateway to make LBS more reliable. Third parties need just one connection via an XML interface to find the location of a mobile handset on any of the four major UK network operators. All numbers that can't be located will be put into a table and then processed as the location gateway tries to locate the number on all other networks.Ê

Lower costs

Actual GPS position fixes are free. You buy the hardware and the vehicle locates itself when asked to do so or at periodic intervals. The cost comes in because there has to be some method of transmitting that location data from vehicle to base. However, those costs have come down dramatically since the advent of GPRS (General Packet Radio Service), whose always-on capability can effectively banish the per-message rate. It enables operators to track vehicles on a virtually continual basis for a single monthly flat fee.

But that doesn't mean you can track vehicles as often as you like and still pay the same amount. While network costs are aggregated over the fleet, the cost will vary for more frequent updates. Moreover, there are still complaints about poor GPRS coverage in certain parts of the country.

GPRS also boosts the appeal of GSM tracking, of course. However, you pay for each GSM position fix (currently around the 18 to 20p mark), regardless of how the information is transmitted back to you, so operators will need to do a careful cost analysis.

GPS has a distinct advantage if you don't actually want to download your positioning fixes in real time at all, and are content instead to capture them on the vehicle-mounted equipment and analyse them when the vehicle gets back to base. Earlier GPS-based systems often relied on this approach; it was the standard modus operandi of leading supplier VeMIS, for instance, until the company added real-time tracking a couple of years ago.

Honeymoon period

Even when operators have a live tracking capability, many suppliers have found that after an initial "honeymoon" period characterised by frequent live position updates, users are often quite happy with after-the-event tracking and analysis. An obvious advantage is that this cuts down or even eliminates transmission costs, offering significant savings. Your on-board computer can capture as many fixes as it has the memory to store, and it won't cost you any more.

By contast, with GSM tracking, there is no obvious way to capture fixes without paying for each instance. After all, that's how the phone networks make their money. Their data may allow you to do post-analysis of journeys, but you still have to capture it in the first place, and pay when you do.

Most LBS companies charge to register a mobile on their service, although not all do. One of the exceptions is FleetOnline, which waives the charge and also arranges for payment to be handled automatically through mobile phone bills. It already claims over 40,000 subscribers.

Verilocation charges £5 to track up to five phones a month for a registration fee of just £5. There are also annual plans. Followus charges on a pay-as-you-go basis, with packages starting at £4.99 for multiple location credits. The more credits you buy, the cheaper they become. "Many companies don't need to know where their vehicles or workers are at every moment of the day," says operations director Kevin Brown.

Useful role

One question many users of existing GPS-based tracking systems might ask is whether there is any point in switching to GSM. Perhaps not, if they have already invested extensively in GPS tracking; but there could still be a useful role for pure GSM tracking even in such fleets. Logistics companies often rely on subcontracted and rented vehicles to deliver goods. It is often not feasible to insist that these have GPS tracking facilities, but operators can easily provide the driver or subcontractor with a trackable GSM telephone to help plug the data gap.

Then again, some suppliers of GPS-based tracking systems offer removable packs that can be transferred relatively easily between vehicles. One is Microlise, while another is rental group Northgate.

Ultimately, LBS services could prove most attractive for locating mobile employees - from both an efficiency and a security point of view, and because it can help ensure they are discharging their employers' legal responsibilities. The Health and Safety Executive has begun to address the security of lone workers, insisting that companies have the same duty of care towards their remote and mobile employees as those working in the office. Being able to locate mobile employees is one method of demonstrating due diligence in this respect.

Other tracking technologies

Although in recent years GPS has figured in the majority of UK-based tracking systems, and GSM/LBS tracking now seems to be emerging as the main alternative, these are by no means the only technologies available for tracking vehicles and people.

For many years Datatrak, now part of the Siemens group, has operated its own dedicated network of "beacons" or transmitters to provide a proprietary positioning service to users. It is said to cover almost the whole of the UK. Datatrak also has its own wireless communications network, so effectively it operates independently of any third-party network.

There is also the alternative of a satellite-based system. Eutelsat and Inmarsat are the two big names here. Eutelsat provides positioning information via two geostationary satellites covering virtually the whole of Europe, providing accuracy to the nearest 100 metres. Inmarsat has four geostationary satellites around the world.

These organisations offer a true satellite-based communication service. Admittedly, you pay for the tracking as well as the comms, but these systems have proved particularly appealing for users roaming over wide areas. Qualcomm is now a leading proponent of the Eutelsat system for tracking, while Satamatics is a key user of Inmarsat.

In the UK, a newer option is the service now being rolled out by QuikTrak, which again is setting up dedicated transmitters to provide positioning fixes. In this case it is using spread-spectrum technology, as applied elsewhere in wireless local-area networking.

In one respect QuikTrak's approach has something in common with GSM tracking; the positioning information is captured within the network, rather than locally by hardware carried by individual mobile units - meaning mobiles don't need conventional transmitters to report their position. The service is only available at selected locations so far (London for instance), but is being extended steadily across the country.

Faster and cheaper tracking: what the future holds

Both GPS and GSM tracking technologies are being enhanced to give better accuracy. Assisted GPS, or A-GPS, is already available in some countries, and speeds up the time it takes to get a position fix. GPS satellites broadcast data at a comparatively slow rate of 50 bits per second; by contrast, with A-GPS the terminals are able to search more efficiently, because some of the data that GPS receivers usually download from the satellite is held on a GSM server, speeding up the computation.Ê

Position fixes are also quicker; they take less than five seconds, compared with at least 15 seconds for a standard GPS fix. A-GPS can be network-based or handset-based. It is currently trialling in Japan and Korea where accuracy is up to 60 metres.

For really accurate positioning there is already a system called differential GPS or D-GPS, which in effect corrects the "fix" to a 1 metre accuracy by means of a terrestrial reference signal. This is available in various countries including the UK, but it's aimed mainly at applications such as surveying that need a high level of accuracy. For routine applications the licence fee would probably be prohibitively expensive.

The main rival to A-GPS looks like being Enhanced Observed Time Difference (E-OTD) which will improve GSM location accuracy. One reason positioning accuracy is relatively poor on both GSM and the emerging 3G networks is that neither uses synchronised timing signals. So although the phone will triangulate its position using three transmitters, the time signals from the transmitters may not synchronise with each other.

A spokesman for Cambridge Positioning Systems, one of the companies at the forefront of developing new mobile technologies, explains: "All signals drift over time, but vary in how quickly that happens. Each cell needs readjustment every few hours, and some networks have less drift than others. Our experience in the UK is that Vodafone cells stay synchronised longer than those on other networks."

However, CPS says the next generation E-OTD will have greater appeal. "The technology will allow the handset to make measurements from at least four transmitters, doubling accuracy. There will be only a minimal add-on cost for handsets, and little extra infrastructure for the networks."

CPS's Matrix solution puts the location server on the network, sitting between GPS and Cell-ID. Phones report to the server which base stations they find. The Matrix server builds up a map of the base stations and their timing signals. Once the signals are synchronised it is possible to get accurate GSM triangulation and position fixes.

The next generation of positioning technology could well combine the best of GPS and GSM location technology. Forecasts are that a hybrid phone with a combined GPS-GSM capability will be on the market within 18 months. But these phones will be aimed at the top end of the market. What the network and LBS providers are anticipating is that the arrival of enhanced GSM tracking could obviate the need for this, delivering accurate location technology to the masses.

Even then, however, the pricing structure may deter logistics fleets from switching from their tried and trusted GPS tracking systems. After all, why pay for something you are currently getting for free, courtesy of the US government?