Comparison of downlink mobile positioning methods for the UMTS FDD mode without using IPDL periods

This paper deals with position location (PL) methods, in the context of wideband code division multiple access (WCDMA) mode of UMTS, based on time difference of arrival (TDOA) in the downlink (DL) scenario. The considered PL techniques suppose that the mobile is able to capture signals from at least three base stations (BS). In order to assure that a mobile receives signals from far located BS´s with an acceptable signal to noise ratio (SNR), several techniques have been proposed: one example is the introduction of an idle period downlink (IPDL) which presents the disadvantage of reducing the system capacity. We compare here several solutions to the hearability problem which do not use IPDL and would allow to obtain a good estimation of the far located BS´s time of arrival (TOA).