A Probabilistic Shaping Scheme for Bit-Interleaved Coded Modulation With Iterative Decoding

In this letter, a probabilistic shaping (PS) scheme for bit-interleaved coded modulation with iterative decoding (BICM-ID) between low density parity check (LDPC) decoder and demodulator is proposed. Compared to conventional LDPC-coded 8-quadrature amplitude modulation (QAM) system on additive white Gaussian noise (AWGN) channel, when spectral efficiency (SE) is 2.10 bits/s/Hz, the proposed PS-8QAM scheme for BICM-ID can obtain 0.73 dB theoretical gain, where the simulated error performance gain is 1.02 dB with frame error rate (FER) at 10−3. Compared to conventional LDPC-coded 32QAM system on AWGN channel, when SE is 3.75 bits/s/Hz, the proposed PS-32QAM scheme for BICM-ID can obtain 1.08 dB theoretical gain, where the simulated error performance gain is 1.10 dB with FER at 10−3. Both the information-theoretic analysis and simulated error performance show that the proposed PS scheme for BICM-ID is reliable, which is suitable for non gray mapped constellations.