A convolutionally coded CDMA system with transmit diversity over Nakagami fading channels

The performance of a multiple-input multiple-output (MIMO) code-division multiple-access (CDMA) system, using space-time spreading (STS), is examined over a frequency-flat Nakagami-m fading channel. The convolutionally space-time coded system employs a decorrelator detector with N=2 and L antennas at the user side and base-station (BS), respectively. Considering binary-phase-shift Keying (BPSK) transmission, the pairwise error probability and the corresponding bit-error-rate upper bounds are obtained for both slow and fast fading channels. The derived error bounds, when compared to system simulations, are shown to be tight at high signal-to-noise ratios. Furthermore, our analytical results explicitly show the achieved system diversity in terms of the number of transmit and receive antennas.