A design of high speed multi-path searcher using dual scrambling code generators for WCDMA

Unlike in the IS-95 based synchronous CDMA system, each base station (BS) operates asynchronously and use Gold code sequence in the 3GPP asynchronous WCDMA system. Therefore, for soft handover (SHO) case, the searching time for all active set members of BS becomes very long. In order to maintain good link quality during the handover execution, it is very important to reduce the handover search time for the target BS. In this paper, we propose an efficient searcher architecture and algorithm to reduce handover search time for asynchronous WCDMA system. We introduce double dwell serial searcher architecture with dual scrambling code generators and search algorithm, which reduce search time in handover environment with small increase of hardware complexity. Average search time performance of proposed scheme is analyzed for soft handover environment. And the real threshold values of search mode and verification mode are investigated. The results analyzed in this paper may be applied to the designing of the user equipment (UE) multi-path searcher of 3GPP WCDMA system.