Infrared Wireless Communications using Complementary Sequence

The performance of an infrared wireless system using direct sequence spread spectrum techniques in multipath channels depends very much on the partial correlation properties of the spreading sequences used. Ideally, a spreading sequence should have zero sidelobes in its periodic and aperiodic auto-correlation functions in order to eliminate multipath dispersion. Unfortunately, no such ideal sequence exists in the binary field. In this paper, a new spread spectrum based binary modulation scheme is proposed in which a set of complementary sequences is transmitted simultaneously such that the sum of their aperiodic auto-correlation and cross-correlation functions are impulsive or near impulsive. The system modelling and bit error rate analysis is presented. Results show that the new scheme is able to remove multipath dispersion almost completely.