Reed Solomon coded M-ary hyper phase-shift keying

Abstract

Non-binary 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 satellite communications uplink. MHPSK is a spectrally efficient modulation technique that uses four orthonormal basis functions to increase the 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 keying (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 similar 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, Reed Solomon coded symbols are assumed to be transmitted with MHPSK. MHPSK, MPSK, and MQAM are compared in terms of probability of bit error and bandwidth efficiency, where the number of bits per coded symbol are typically designed to match the number of bits per channel symbol.