Improving the robustness of target cell search in WCDMA using interference cancellation

In WCDMA, a common sequence of 256 chips called the primary synchronization channel (P-SCH) is transmitted periodically by all cells to assist the terminal to locate the slot boundary, which then leads to cell identification following the multi-stage cell search procedure. In the event that two or more cells have similar propagation delay profile with respect to the terminal, the P-SCH of the stronger cell may overshadow that of a weaker one. To avoid the misdetection of the overshadowed target cell and improve the robustness of the cell search procedure, this paper studies the performance of a proposed improvement, which regenerates the P-SCH of the strong serving cell using channel information available at the demodulator and then subtracts it to reveal the hidden target cell. Simulation results show that when the propagation delay profiles of the two colliding cells are within 1/2 chip, the subtraction method can reduce the acquisition time from the order of several seconds to a few hundreds of milliseconds.