Assisted-GPS (A-GPS) is a handset-based location solution that requires GPS receiver chipsets to be included in the subscriber mobile phones.
Using satellites to detect location of mobile devices.
This solution has been deployed in CDMA2000 and iDEN networks, where the location of a GPS-equipped mobile device is obtained by comparing signals received by the device from multiple GPS satellites.
A-GPS works well in direct line-of-sight conditions.
A-GPS works very well in conditions where direct line-of-sight with the satellites (open sky conditions) can be maintained, such as in suburban and rural areas. For mission-critical applications, such as law enforcement, A-GPS technology is often complemented by another geo-location method, since the GPS receiver in the phone can be easily disabled by the end user.