Improvements on acquisition of secondary synchronization channel in W-CDMA

The timing relationship between base stations is asynchronous in the W-CDMA system. So a three-step cell search algorithm is introduced in 3GPP protocols in order to quickly identify the special base station. The second step, secondary synchronous channel (S-SCH) acquisition, is critical, but the computational complexity of the conventional matched filter banks method is very large. We propose the partial fast Hadamard transform (PFHT) according to the S-SCH structural property, which reduces the computational complexity to almost 70 %. On the other hand, a distributed sub-graph search algorithm is put forward to save more complication than RS code table brute-force search. The hardware complexity is dramatically cut down by the improvement scheme, which is valuable for engineering applications.