Turbo-coded/multi-antenna diversity combining scheme for DS/CDMA systems

In this paper the performance of a combined turbo coded and antenna diversity scheme to synchronous direct-sequence code-division multiple-access (DS/CDMA) communication over fading mobile radio channels is considered. Turbo codes have a built in structure that is suitable for diversity techniques to improve the quality of communications. The binary input data to a rate 1/(M+1) multiple turbo encoder produces M+1 coded bits, which, in turn, are assigned through suitable puncturing patterns to M different antennas and transmitted from each antenna simultaneously. The novelty of the transmission scheme, is that the original single-antenna rate-1/2 turbo coded system is transformed into a more powerful rate-1/(M+1) turbo code. The bit error rate performance of the proposed combined antenna and turbo coding diversity combining scheme is studied by means of simulation for a quadrature phase-shift keying (QPSK) DS/CDMA system on a non-frequency selective Rayleigh fading channel. Employing the turbo-coded/multi-antenna diversity combining scheme it is shown that lower bit error rate performance can be achieved, compared to a conventional single antenna scheme employing the same coding strategy.