8-PSK trellis codes on Rayleigh channel

Trellis-coding techniques are considered as a means of improving the reliability of 8-PSK (phase-shift keying). It is shown that the combination of a rate 2/3 convolution code and 3-b interleavers provides a good modulation/coding method for the Rayleigh channel. The author proposes a suboptimal coded system that combines a regular convolutional code, bit interleaving, and an appropriate decoding technique. The bounds on the error performance of this approach indicate that the best convolutional code in conjunction with 8-PSK modulation and appropriate soft-decision metric is an attractive means of improving the reliability. In particular, over a Rayleigh channel this system requires E_b/N₀ of about 14.5 dB to provide a bit-error rate of 10^-5 (for a code with 64 states), which is 1.2 dB less than the requirement for the baseline system, which uses the optimal trellis codes for the Rayleigh channel