Performance comparison of stepwise parallel and serial cell search in WCDMA

For three-step cell search in WCDMA system, a stepwise serial scheme is conventionally employed, where each step operates in serial. In order to reduce cell search time, a stepwise parallel cell search scheme can be considered, where each step works in pipelined operation. However, in this parallel scheme where the processing time in every step is equal, excessive accumulations are caused in step (1) and step (3), because the code period for step (2) is much longer than those for the other steps and the effect of accumulations becomes saturated with the number of accumulations. This reduces the benefit of the parallel scheme. In this paper, the performance of parallel cell search is analyzed and compared with that of serial cell search over Rayleigh fading channels. The results are presented for varying parameters. Finally, it is shown that the performance of parallel cell search can be improved by adjusting appropriately the processing time in each step.