Performance of multiple trellis coded modulation on a vegetatively shadowed mobile satellite channel

A multiple trellis coded modulation (MTCM) scheme is investigated for a satellite-to-mobile downlink. In particular, the performance of a rate 4/6, multiplicity 2, trellis coded, differential 8 phase shift keying (D8PSK) scheme is investigated by computer simulation for a vegetatively shadowed (VS) channel that typifies satellite-to-mobile communications. The improvement of the MTCM over a rate of 2/3, multiplicity 1, trellis coded, D8PSK scheme and an uncoded differential quadrature phase shift keying (QPSK) scheme is also given. It is shown that in the VS channel, under average shadowing conditions, the rate 4/6 MTCM scheme performs 6 dB better than the rate 2/3 TCM scheme optimized for the additive white Gaussian noise channel at a bit error rate of 10 ^-3. The performance of the rate 4/6 MTCM scheme in the presence of channel interference and the effect of a nonlinear traveling wave tube amplifier are also investigated