Advanced Forward Link Trilateration (A-FLT)

A-FLT is a handset-based position location technology (primarily used on CDMA networks) that works by using measurements, taken by the handset, of signals from nearby base stations, and reporting the time/distance readings back to the network, which are then used to triangulate an approximate location of the handset. In general, at least three surrounding base stations are required to obtain an optimal position fix. Unlike GPS (or A-GPS), AFLT does not use GPS satellites to determine location but rather a time difference of arrival (TDOA) technique. TDMA (Time Division Multiple Access) is required to transmit location data and is commonly paired with A-GPS to form a “hybrid solution”; an alternative to purely “handset-based” or “network-based” location technologies. (As AFLT is well-suited for urban environments with close proximity of base stations whereas A-GPS is more advantageous in suburban and rural areas having low base-station densities)