Long block length reed solomon coded M-ary hyper phase-shift keying

Abstract

Forward error correction (FEC) coding in conjunction with M-ary hyper phase-shift keying (MHPSK) is considered in order to improve the robustness of a high spectral efficiency satellite communications link. MHPSK is a spectrally efficient modulation technique that uses four orthonormal basis functions to increase the Euclidean distance between different symbols in the signal space. Spectral efficiency and probability of bit error are two key figures of merit used to evaluate digital modulation techniques. The use of four orthonormal basis functions provides an advantage over traditional modulation techniques such as M-ary phase-shift keying (MPSK) and M-ary quadrature amplitude modulation (MQAM) that only possess two degrees of freedom. MHPSK offers an improvement in bit error performance over other spectrally efficient modulation techniques for the same average energy per bit-to-noise power spectral density ratio and the same spectral efficiency. As a result, MHPSK offers a novel way to improve both throughput and reduce power requirements using easy to generate waveforms. In this paper, long block length Reed Solomon (RS) codes are used to encode information symbols which are then transmitted with MHPSK. The results are compared with those obtained when data is encoded with the digital video broadcast (DVB) standard rate r = 0.9 low density parity check (LDPC) code commonly employed in satellite communications for high spectral efficiency broadcasts and transmitted with either 8-PSK, 16-PSK or 16-QAM. The performance obtained with MHPSK, 8-PSK, 16-PSK, and 16-QAM is compared in terms of probability of bit error and bandwidth efficiency when long FEC block lengths are used.