Application of block coded modulation (BCM) in direct-sequence spread-spectrum communication

BCM is a kind of coded modulation scheme proposed by Imai and Hirakawa (1977) which can obtain coding gains without compromising bandwidth efficiency. This paper investigates the application of BCM in DS/SSMA communication. In our system, a biorthogonal set of sequences is used to allow redundancy to be added via coding. In this way the Euclidean distance is increased when the code rate increases if we allow as many signature sequences as the number of signal points of the signal constellation of the original system. Simulation results are presented to show that our scheme can achieve large coding gains over those of an uncoded system of the same bandwidth expansion and data rate.