CONVOLUTIONALLY INTERLEAVED PSK AND DPSK TRELLIS CODES FOR SHADOWED, FAST FADING MOBILE SATELLITE COMMUNICATION CHANNELS

Using a model from the literature, the performance of convolutionally interleaved phase shift keying (PSK) and differential phase shift keying (DPSK) trellis codes for digital speech transmission over a shadowed mobile satellite communication channels is determined via digital computer simulation. First the characteristics of fading channels are examined and analyzed in terms of the probability distributions of amplitude, phase, and burst errors. A statistical method, using a histogram approach, is utilized along with the simulations of fading channels to generate these probability distributions. A test for channel burst error behavior is also presented. Having the background knowledge of the burst error distribution, a periodic convolutional interleaver/ deinterleaver is designed to be used with trellis coding to combat slow fading in digital, shadowed mobile satellite channels. This interleaver has less than half the time delay for the same bit error performance relative to a block interleaver, an important consideration in digital speech transmission. The results show that the periodic convolutional interleaver provides considerable improvement relative to techniques in the error and time delay performance of mobile satellite communication channels for up to average shadowing conditions. © 1990 IEEE