Artilium

Monday, June 08, 2009

The Need for Continuous Location Technology

There are numerous location technologies available for mobile phone location. It is convenient to consider the following 3 categories.

1. GPS
2. Cell-ID
3. Handset measurements

The GPS receivers built into handsets tend to give accurate location data assuming that the GPS is switched on, that it has clear visibility of the sky, and that the receiver has managed to synchronise. Of course the problem with GPS is that you must have good visibility of the sky which rules out indoor operation in many cases, then you must allow time for the receiver to lock to the visible satellites, and finally the drain on the handset battery is enormous relative to the normal power consumption of the handset.

Cell-ID is a network based technology whereby the mobile terminal is located by determining which base station the terminal is registered to. This enables the network to estimate the location of the terminal within the coverage area of the current cell. While this is not very accurate it does not require a specialist handset. The technology can be enhanced slightly by considering other factors such as the timing advance signal which allows segmentation of the coverage area based on a probable distance range from the mast. As well as location inaccuracies, a disadvantage of Cell-ID is that a location has to be requested for the network each time and there is a cost to the subscriber for each request made.

Handset measurements are based on the network signals which are measured by the mobile terminal and can be used in a number of ways. In GSM and 3G network signals can identify parameters of the broadcasting cell and it is often possible to identify parameters for adjacent cells too. The location of the terminal can then be calculated based on knowledge of the location of the signal sources. This is the method used by Artilium and when applied intelligently there are a good number of advantages to this type of location technology.

So why has Artilium chosen this third option as the basis for its location technology? Well first it should be stated that we do also embrace GPS and Cell-ID technologies when available, but the point is they are not always available or always-on. The handset measurement technology can provide always-on continuous location and using Artilium’s proprietary Tri-cell Intelligent Location System (TILS) is generally much more accurate than Cell-ID location. Additionally the technology has a low operational cost and there is a minimal impact on the terminal power consumption. Artilium’s Mobile Applications Platform is the means to deliver multiple applications to subscribers and incorporates TILS as standard. Therefore the platform provides continuous location technology and can support any application requiring location at any time.

So what types of applications have the need for continuous location? A general answer to this is, any application that relies on location events triggering actions. Imagine a service where a parent can be informed when their child leaves the school.  For this application GPS would not be ideal (since the device would need to be equipped with GPS, this would drain the battery and synchronisation indoors may not be possible). Alternatively Cell-ID would need to be polled continuously (which is very expensive) and the accuracy is not great. With TILS the location is updated continuously so the event “leaving school” is detected quickly and the action might be to send the parent an SMS.  The same principal can be applied to applications such as the delivery of a package – tell me when my parcel is about to arrive. With the growth in mobile social networking it is becoming very useful to know when you are near to your friends – and you simply cannot expect all your friends to turn on their GPS receivers all of the time!