Fast cell search algorithm in idle mode for inter-cell asynchronous W-CDMA mobile radio

This paper proposes a fast target cell search algorithm used during intermittent reception in the idle mode of a mobile station (MS) for inter-cell asynchronous W-CDMA mobile radio. In the proposed scheme, since the base station (BS) informs a MS of the relative average received timing differences between the scrambling code of its BS and those of the surrounding BSs in addition to the scrambling codes, the MS only has to search over the restricted timing duration for the informed scrambling codes. Therefore, the target cell search (i. e. , in which the number of candidate cells is limited) can be achieved as fast as in inter-cell synchronous systems. A computer simulation demonstrates that the target cell search time per one super frame (= 720 msec) at the cell detection probability of 95% is accomplished within 5. 9msec (this corresponds to the intermittent time ratio required for the target cell search to become 0. 82%), when the transmit power ratios of the common pilot channel (CPICH) and common control physical channel (CCPCH) required for cell ; search to a dedicated traffic channel (DTCH) are 3 and 6 dB, respectively. In this simulation, the average power delay profile was generated by averaging the instantaneous ones (it was coherently accumulated pilot signal over a 512-chip duration (= 125/isec) using 4 correlators) over a period of three super frames for 19 target cell-site candidates using the search window with a 10-chip duration (= 2. 4 /<sec).