This paper investigates the cell search time performance of our previously proposed three-step cell search method in a two-cell site environment by laboratory and field experiments supporting asynchronous cell site operation, which is one of the most notable features of wideband direct sequence code division multiple access (W-CDMA) mobile communications. The cell search methods used in the paper are based on the ongoing third generation partnership project (3GPP), in which our original scheme was refined with respect to several points in order to reduce the complexity of the receiver. The experimental results demonstrate that the method achieves the fast cell search time of less than one second in real multipath-fading channels. The cell search is accomplished in less than approximately 700 msec at 90% of the detection probability when 4.7% and 0.5% of the total transmit power of a cell site is assigned to the common pilot channel (CPICH) and synchronization channels (SCHs), respectively, in a two-cell site environment. We also elucidate that the cell search time at the detection probability of 90% using time switched transmit diversity (TSTD) is decreased by approximately 100 msec compared to that without TSTD in low-mobility environments such as the average vehicular speed of 5 km/h with a transmit power assignment of the CPICH of 4.7%.

This paper proposes and investigates a vehicular radar system that can measure the distance to, the relative speed of and the direction of arrival (DOA) of the reflected waves from multiple targets or vehicles using the direct-sequence spread spectrum (DS-SS) technique. In particular, we propose a DOA estimation scheme using a multi-beam antenna. In order to show that the proposed system can accurately measure the above mentioned quantities, the performance is evaluated numerically in a multipath environment. Moreover, optimal multi-beam pattern is derived to minimize error probability of DOA estimation.

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 5.9 msec (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 µsec) 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 µsec).