SPC-APPM coded modulation for deep-space optical communications

A coded modulation scheme for deep-space optical communications is proposed, which is composed of an outer single- parity-check （SPC）-based product code, an interleaver, a bit-accumulator and a pulse-position modulation （PPM）. It is referred as SPC-APPM code, which is decoded with an iterativc demodulator-decoder using standard turbo-decoding techniques. Investigations show that the scheme has the advantages of low encoding and decoding complexities, good performance and flexible code rate for all rates above I/2. Meanwhile, simulation results demonstrate that the SPC-APPM provides the performance similar to the low-density parity-check-APPM （LDPC-APPM）, superior to the LDPC-PPM and product accumulate code-PPM （PA-PPM）, although inferior to serially concatenated PPM （SCPPM）. At the bit error rate （BER） of 105, the performance of SPC-APPM is about 0.7 dB better than LDPC-PPM and 1.2 dB better than PA-PPM.