Coded M-PSK Modulation using Convolutional Self-Doubly Orthogonal Codes

In this paper, coded modulation technique based on the use of convolutional self-doubly orthogonal codes (CSO²C) and threshold iterative decoding is presented. Two different methods of coded modulation are considered. The first approach is based on a conventional pragmatic scheme. In the second approach, all information bits are coded and a simpler Gray coding is used for the bit-to-symbol mapping. Simulation results indicate that for a bit error rate of 10^-5 , the pragmatic 8-PSK coded modulation scheme with R = 2/3 coding rate provides a coding gain of 3 dB as compared with the error performances of the uncoded QPSK system. The simulation results also demonstrate that by using the second approach, a larger coding gain of 4.5 dB is obtained when compared with uncoded QPSK modulation.