On relation among time delay and signal strength based geolocation methods

The time-of-arrival (TOA), time-difference-of-arrival (TDOA) and signal strength (SS) methods have been widely accepted as three principal techniques for positioning a mobile station (MS) in a wireless communication system. To the best of our knowledge, previous studies tend to treat these methods separately, and less analytical results on their relationship have been reported. We first examine the link between the TOA and TDOA methods. We provide an analytical explanation for the claim that, given a set of BS locations and an MS position, the TOA method should achieve a higher positioning precision than its TDOA counterpart. However, the two positioning methods may attain the same level of accuracy under certain conditions. We then investigate the tradeoff between the accuracy limits of the TOA and SS based methods, which leads to our proposal of a hybrid distance estimation scheme that combines both TOA and SS data.