Inner Code Optimization for High Rate Faster-than-Nyquist

Faster-than-Nyquist (FTN) can improve the spectrum efficiency (SE) of transmission system. The inner code optimizations including precoder and doping code are introduced for high rate FTN in this paper. The optimal transmission waveform for high rate FTN system can be designed by optimizing the transmitter's precoder. Particle swarm optimization (PSO) is firstly employed to optimize the precoder for FTN. We further optimize the inner decoders EXIT characteristic by applying doping method. Simulation results verify that our method has 0.5dB precoding gain compared with the non-precoding scheme at the same SE; the optimization high rate FTN system has a 1.2dB gain compared to high order Nyquist at the same SE. The results demonstrate that high rate FTN is an efficient mechanism for improving the SE and the proposed joint optimization method is efficient.