Aug/Sept 2007

Assisted GPS is already enhancing the accuracy of tracking systems, and later Galileo will improve performance further; and an explosion in location-based services is likely to fuel demand for this new technology. Sharon Clancy reports

When reports of drivers being misdirected by their satellite navigation systems hit the television and radio news, it's a good indication that what originated as a business tool to save mobile workers time has progressed into mainstream consumer use. It's also a reminder that the technology may not always work quite as it should. But that is already changing.

Certainly there's no doubting that over the past two years there has been massive uptake of portable satellite navigation systems - fuelled by falling costs and improvements in the technology. Now experts predict that the market for phone-based personal navigation systems will also explode over the next few years. Indeed, a new set of initials seems to be coming into use as a shorthand for this type of system - always a sign that a new technology is filtering into the mainstream. It's GNSS, standing for Global Navigation Satellite System.

Tracking the device or vehicle accurately is crucial to these navigation developments, and will be even more critical in underpinning GNSS services.

 

The GPS (Global Positioning System) satellite network is, of course, used by many tracking systems for location fixes, and will be enhanced when the EU's Galileo satellite-based system goes live in 2013. Galileo is expected to reduce GPS black spots, providing users with more accurate and reliable position fixes.

In the meantime, mobile phone networks have already improved the accuracy of cell-identification tracking with technologies such as U-TDOA (Up Time Difference Of Arrival). By measuring the time it takes for a signal from a phone to reach the cell, the system can calculate location more accurately, although it is still reliant on the number of mobile masts in the area.

Assisted-GPS

Assisted-GPS, or A-GPS, is now starting to appear on top-of-the-range mobile phones. It combines technology inherent in mobile networks themselves with GPS satellite location, and is spearheading a new generation of tracking and location systems.

As most people now appreciate, impressive though GPS is for wireless location, it's not perfect in all situations. Tall buildings and heavy trees can prevent a clear line of site to the satellite, reducing signal strength and making it difficult to get a position fix. A-GPS helps compensate for weak signals, making tracking possible even inside buildings.

A-GPS can be network-based or handset-based, but in either case it also cuts down the time it takes to get a position fix. Typically, it can reduce this to about five seconds from up to 15 seconds for a standard GPS fix.

GPS satellites broadcast data at a comparatively slow rate of 50 bits per second; the GPS receiver on the terminal has to download this data and compute its position accordingly. With A-GPS the GPS receiver on the device has fewer frequencies to search to find a satellite signal. It can dwell on each signal for longer, so can decode lower-strength signals.

So A-GPS offers a fast Time to First Fix (TTFF), regarded by the networks and providers of location-based services as crucial for user acceptability. The providers have learnt the lessons from the poor performance of early mobile WAP services , when the novelty of mobile Internet failed to overcome users' frustrations with the slowness and clunky downloads. TTFF times are faster with A-GPS because the GPS receivers on the mobile devices are not dependent on the GPS satellites to obtain the navigation data that they need; they get it from an A-GPS server instead.

Offering GPS suits the mobile network operators, as it can provide another revenue stream for navigation data downloads and other location-based services. Top-of-the-range next-generation mobile phones are beginning to incorporate GPS receivers as standard. Smart phones already provide Internet access, so downloading the extra data for a navigation application is comparatively fast. That time is reduced yet further when the phone is on a 3G network, and will be faster still on the High Speed Downlink Packet Access networks (HSDPA) mobile phone networks that are beginning to go live around the world.

Cell networks

In the United states, the mobile networks can deliver enhanced location-based services on the US emergency 911 channel, using technology developed by US-based True Position. This demands minimal cost to the consumer and automatic location of the driver making the 911 call.

Over in Europe, the EU is developing a programme called e-call, which requires cars here to be similarly equipped, and True Position's marketing communications manager, Brian Varano, reckons e-call will also drive location-based services in Europe.

'U-TDOA is a great technology for phone-based tracking and LBS,' he says. 'The location measurement units are in the network base stations. No new hardware or software has to be placed in the phone, and when used in combination with Assisted GPS, it gives sub-25 metre accuracy. '

Varano points out that no single technology has been identified that provides optimal performance across every type of location, whether it be urban, rural, suburban or indoors. 'For this reason, it is often valuable to integrate multiple types of positioning technology to meet the high standards required. A hybrid solution can deliver high performance tracking services regardless of device or environment.'

Galileo

After a hiccup over costs and revenue projections a couple of years ago, Galileo, the satellite navigation project jointly funded by the European Union and the European Space Agency is now expected to come fully on stream in 2013, with the first satellites going live in 2011. The 30 satellites will be in a medium-earth orbit and at an angle to the horizon that will avoid the blackspots that occur with high-orbit GPS satellites. Galileo will not interfere with GPS signals.

Unlike the US military-owned Global Positioning Satellite System, Galileo has been designed from the outset for civilian use, and there will be several layers of access. The Open service will offer free access to the public for location purposes. On different channels will be Public Regulation, Search and Rescue, Safety-of-Life, and Commercial Services.

'GPS and Galileo should not be viewed as competing standards,' says Steve Hickling, product manager for Spirent, which tests GPS equipment and services and has equipment that simulates GPS and Galileo signals. 'They are complementary, and together will give users a better experience than they have now.'

He adds: 'Interoperability between positioning systems will be critical if the market is to continue to grow, and new navigation devices will have to be seamlessly compatible with the two GNSS systems. They will also need to be intuitive enough to combine input and interpret information from the two systems intelligently, offering the consumer the most accurate data available for any given situation.'

Hickling says device manufacturers should start planning now for the launch of Galileo in 2013. 'Over the next ten years the number of GNSS signals available will more than double, not only in terms of the number of satellites, but also in the number of signal types and services available. Equipment vendors and infrastructure providers must iron out any problems before the system goes live. No one in the industry wants to see GNSS technology discredited by repeated failures and poor system implementations.'

PANEL

A-GPS in action

Trailer tracking units are often mounted on the roof of the trailer in order to give the devices a clear view of the sky. However, Isotrak is using A-GPS in its unpowered trailer tracking units so they can be mounted covertly on the chassis - a benefit that will also apply to flat-bed container-carrying trailers and temporary hired trailers. There is no external antenna, and Isotrak says the device can be fixed anywhere suitable on the chassis. It also maintains that fitting time takes no more than three minutes, and requires minimal tooling.

The tracking device itself can be set to record at ten-minute intervals if required, and can be reconfigured remotely to suit the specific requirements of an operation.

PANEL

Affordable phone-based GPS tracking

Logistics Telecom has developed a tracking application for mobile phones called Logicom. The Standard version uses mobile network cell-based tracking, while the Pro version is designed for GPS-enabled phones. In both cases, the data is sent to the company's Web-based server, where users can view and track their assets.

The pricing plan is designed to make things as simple as possible, with GPS-tracking costing 15p per day. Managers can turn off the GPs tracking on days it's not required - at weekends, for example. The GPS function also allows Logicom to notify employers when drivers exceed the speed limit.

Another cost-saving feature is messaging. Using the service to send messages to drivers is, claims the company, 6,000 times cheaper than SMS messaging. A proof-of-delivery function is being added shortly, and companies who want it will be able to download it over the air to devices running Logicom.

The application runs on any mobile phone, although the company is currently recommending users to opt for Orange's M700 GPS-enabled device, because the network operator charges for only the amount of data sent (there's no rounding up to the nearest megabyte).

Logistics Telecom points out that GPS-enabled mobile phones are more expensive to buy; so if, for example, you have 25 mobile workers but only need very precise location fixes for 10, only those 10 need to be GPS-enabled. The other 15 can be on the standard tariff.