M-ary hyper phase-shift keying with Reed Solomon encoding and soft decision reliability information

Reed Solomon (RS) forward error correction (FEC) coding in conjunction with M-ary hyper phase-shift keying (MHPSK) and soft decision decoding is considered in order to improve the robustness of a high spectral efficiency, non-linear satellite communications link. In this paper, a system that utilizes RS encoding of the information symbols which are then transmitted with MHPSK is evaluated in terms of probability of bit error and spectral efficiency. Using standard RS hard decision decoding, the receiver either correctly decodes the received block or returns a decoding failure. In the event of a decoding failure, soft decision reliability information is used to identify received code symbols with a low probability of being correctly received and to generate new code symbol estimates that are used in the traditional RS decoding algorithm. Because the majority of decoding failures are caused when the total number of code symbol errors exceeds the error correction capability t of the RS code by only a few symbols, only a few code symbols must be corrected in order to successfully decode the received block. The performance of this system is compared to a two-subcarrier OFDM system with either 8-PSK or 8-QAM on each subcarrier and single carrier 8-PSK where the data bits are encoded with the digital video broadcast (DVB) standard rate 0.83 low density parity check (LDPC) code. The MHPSK system with RS encoding and soft decision decoding, the two-subcarrier OFDM system with either 8-QAM or 8-PSK on each subcarrier with LDPC encoding, and single carrier 8-PSK with LDPC encoding are compared in terms of probability of bit error, peak-to-average power ratio, amplifier backoff, and spectral efficiency for very long block lengths.