RADIO POSITIONING USING OBSERVED TIME DIFFERENCES

摘要

A system and method are disclosed for obtaining a position estimate of a wireless mobile unit in a wireless communications network by measuring observed time differences (OTDs) between pairs of base stations and without the need to measure absolute time differences (ATDs) between base stations using additional equipment (e.g., Location Measurement Units). Mobile units are positioned using a second position method, for example GPS, that does not require the use of OTDs. Such positioned mobile units also provide OTD measurements. From the OTD measurements and the position estimates obtained using the second position method, ATDs are obtained between pairs of base stations. Other mobile units for which the second position method is either not applicable or not accurate in their current environment may be positioned using measured OTDs and the obtained ATDs.