Performance analysis of uplink handover searcher in asynchronous WCDMA system

Unlike in the IS-95 based synchronous CDMA system, in the 3GPP's asynchronous WCDMA system, it is impossible for the network to estimate the round trip delay between the handover UE (user equipment) and the target base station (BS) before the handover execution, so the uplink handover search window size of the target BS becomes large. In order to get good link quality during handover execution, it is very important to reduce the uplink handover search time at the target BS. We propose an efficient uplink handover search scheme for an asynchronous WCDMA system. Average search time performance of the proposed scheme is analyzed for a fading channel environment. The effects of the non-coherent accumulation length of the search mode and that of the verification mode to the average search time performance are analyzed. The optimal threshold values of the search mode and the verification mode are investigated. The results analyzed in this paper may be useful for designing the uplink handover searcher of 3GPP's WCDMA base station.