Performance analysis of coherent TCM systems with diversity reception in slow Rayleigh fading

Coherent trellis-coded modulation (TCM) systems employing diversity combini ng are analyzed, Three different kinds of combining are considered: maximal ratio, equal gain, and selection combining (SC), First, the cutoff rate pa rameter is derived for equal gain combining (EGC) and SC assuming transmiss ion over a fully interleaved channel with flat slow Rayleigh fading, which permits comparison with previously derived results for maximal ratio combin ing (MRC), Then, tight upper bounds on the pairwise error probabilities are derived for all three combining techniques. These upper bounds are express ed in product form to permit bounding of the bit error rate (BER) via the t ransfer function approach. In each case, it is assumed that the diversity b ranches are independent and that the channel state information (CSI) can be recovered perfectly, Also included is an analysis of MRC when the diversity branches are correla ted-the cutoff rate and a tight upper bound on the pairwise error probabili ty are derived. It is shown that with double diversity a branch correlation coefficient as high as 0.5 results in only slight performance degradation.