Trellis-coded MPSK modulation for highly efficient military satellite applications

Trellis-coded multiple-phase-shift-keyed (MPSK) modulation is an effective technique for increasing the bandwidth efficiency of an existing channel while maintaining at least a moderate degree of power efficiency through coding. The authors consider the application of this technique to increase markedly the capacity of a 25-kHz military satellite channel. It is shown that with only minor modifications to the QPSK modem to incorporate 8 PSK and 16 PSK modulation and no modification to the rate-1/2 coder used to transmit 16 kb/s over this channel, transmission rates of 32 kb/s and 48 kb/s, can be supported at E_b/N₀ levels only moderately higher than for the lower data rate. In fact, it is demonstrated that 48 Kb/s can be transmitted within exactly the same bandwidth and at the same E _b/N₀ levels as that required to transmit uncoded QPSK at 32 kb/s at bit error rate of 10^-5.