Block-coded-modulation for digital radio communications system

The performance of non-frequency-selective (flat) slow Rayleigh fading channels has been studied for bandlimited channels using a technique similar to trellis coded modulation, using a similar technique. A group of very simple block codes is used. Coding is used to implement diversity selection. It was found that over a channel with flat slow Rayleigh fading, an 8-PSK (phase modulation keying) coded-modulation technique achieves almost the same diversity gain (at least 15 dB at 10^-3 word error rate) as a system studied earlier that used rate-2/3 code with 4-PSK modulation. However, the former is without bandwidth expansion, while the latter entails 50% bandwidth expansion