Trellis coded modulation for mobile-satellite communication using space diversity

Abstract

Most of the past studies concerning the decoding performance of trellis coded modulation (TCM) in a fading channel have been based on time diversity using interleaving/deinterleaving. One problem with time diversity is that a large decoding delay is produced due to the interleaving/deinterleaving which depends on the fading interval. This paper considers TCM signals using space diversity which can drastically improve the decoding delay and analyzes the decoding characteristics in Rice fading channels. An analysis is also made of the effect of the Euclidean distance (ED) and the Hamming distance (HD) of the trellis code on the average bit error rate (BER), and it is shown that a code design considering those two distance structures is needed in a channel with severe fading. This paper considers the major application of the proposed method to be digital voice transmission in mobile communication via satellite. Consequently, a simulation is made for the second-order space diversity decoding performance for the trellis coded 8-PSK signal. The optimal trellis coding at the transmitter is discussed for BER = 10−4.