Highly reliable multilevel channel coding system using binary convolutional codes
Keisuke Yamaguchi, Hiroyuki Imai · Electronics Letters · 1987
A multilevel channel coding system using binary convolutional codes is proposed. This system achieves high coding gain. For example, we can obtain an 8-PSK system with rate R = 2/3, which has 6.02 dB coding gain over uncoded 4-PSK and is implemented as easily as Ungerboeck's system with total encoder memory K = 4.