ERROR PERFORMANCE OF INTERLEAVED TRELLIS-CODED PSK MODULATIONS IN CORRELATED RAYLEIGH FADING CHANNELS

We have derived in this paper an exact and easily computed expression for the pairwise error event probability of interleaved coded PSK modulations transmitted over channels with correlated Rayleigh flat fading and additive white Gaussian noise. Both coherent as well as differential detection were considered. In the case of coded DPSK, we found that full interleaving does not necessarily provide the best error performance. This is especially true when the fading is relatively fast and when the autocorrelation function of the channel fading process exhibits an oscillating behavior, like that of a Bessel function. In the cases of coherent detection, or differential detection in channels with relatively slow fading, increasing the interleaving depth always improves the error performance. In these cases, an interleaving depth equivalent to one-fifth to one-quarter the duration of a fade cycle (defined as the reciprocal of the maximum normalized Doppler frequency) is almost as good as full interleaving.