Cell search time performance of three-step fast cell search algorithm employing common pilot channel for forward link broadband OFCDM wireless access

摘要

We recently proposed a three-step fast cell search algorithm employing the Common Pilot Channel (CPICH) for forward link broadband OFCDM wireless access, which comprises the following three steps: OFCDM symbol timing detection using the correlation of the guard interval (first step); frame timing detection and cell-specific scrambling code (CSSC) group detection using the CPICH (second step); and identification of a target CSSC within the detected group (third step). This paper proposes an enhanced detection method in the second step, in which the correlation between two successive OFCDM symbols is normalized by the received signal power of the two symbols, in order to improve the detection probability in the second step. Computer simulation results elucidate that the proposed method is effective in reducing the cell search time when the transmission power of the CPICH is lower than that of the traffic channel (TCH) and when the fading maximum Doppler frequency is high. Concretely, we show that the cell search time at the cumulative distribution of 90% is decreased by approximately 30% with the proposed method and thereby the cell search is accomplished within approximately 2.9 msec when the transmission power ratio of CPICH to TCH for a one code channel is R{sub}(CPICH) = 6 dB.