Assisted GPS for Location Based Services

The mobile operators are seeking for opportunities to create differentiation and increase profit. One powerful way is to provide personalized mobile services. A good example of personalisation is by location. Services based on position are called Location Based Services – LBS. To realise LBS, some sort of positioning method is needed. The two most common positioning methods today are Global Positioning System - GPS and network based positioning. GPS is not fully suited for LBS because you need an additional handset to receive the satellite signals. In network positioning however, you only need a mobile phone, but on the other hand, the accuracy is far less, only between 100 metres up to several kilometres. What technology would be a good positioning technology for location based services? Could A-GPS be such technology? A-GPS is a positioning system which uses the same satellites as GPS, but besides that, it also uses a reference network. The reference network tracks the receiver and the satellites. It also makes some of the heavy calculations that the handsets are doing in the GPS system. That makes the A-GPS receivers less power consuming and more suited to be implemented into mobile phones. Furthermore, A-GPS are more sensitive, meaning that it easier can receive signals when using indoor, for example. The question is if A-GPS technology holds its promises? Does A-GPS really work well in mobile phones? Is the accuracy and availability as good as the theory says and is it possible to implement an own, well working, location based service into an A-GPS mobile phone?