A new scheme for direct sequence spread spectrum radio LANs

A new direct sequence spread spectrum scheme for ISM band radio local area networks using BPSK modulation and matched filter receivers is presented. It employs an optimised 22-chip sequence whose two 11-chip segments are alternately used as spreading sequences for adjacent symbols. Owing to the low cross-correlation between the two 11-chip segments, the inter-symbol interference caused by long delays in multipath channels is significantly reduced. In the paper, a receiver structure using the optimised sequence and time diversity is described and simulation results are given. Compared with the schemes using the short 11-chip Barker code and long M-sequences, the new scheme offers superior system performance.