Fast cell search algorithm for system with coexisting cellular and hot-spot cells suitable for OFCDM forward link broadband wireless access

This paper proposes a new cell-specific scrambling code (CSSC) assignment method and a fast cell search algorithm in the forward link of orthogonal frequency and code division multiplexing (OFCDM) wireless access that are suited to a system of coexisting hot-spot and cellular cells. In the proposed method, one or some CSSC groups and thereby the CSSCs belonging to the CSSC groups are exclusively assigned to hot-spot cells. By detecting the best CSSC assigned to a hot-spot cell with higher priority than the cellular cells, the best cell including the hot-spot cell obtaining the minimum path loss can be detected far faster than by using the conventional cell search method, which is associated with uniform CSSC assignment. The computer simulation results elucidate that by applying the proposed cell search method together with the exclusive CSSC assignment to the hot-spot cells, the detection probability of the hot-spot cell of 0.7 is achieved after the cell search time of 1.7 msec at the average received signal energy of the common pilot channel (CPICH) per bit-to-background noise power spectrum density ratio of the cellular cell of E_bN₀ = 9.9 dB at the cell boundary without notifying the user equipment of the CSSC information of the surrounding cells and when the transmission power ratio of the CPICH to the traffic channel (TCH) for a one-code channel is R_CPICH = 9 dB in a 20-cell layout model.