Channel Decoding for Nonbinary Physical-Layer Network Coding in Two-Way Relay Systems

摘要: In this paper, we propose a generalized channel decoding scheme for nonbinary physical-layer network coding (CD-NC) in two-way relay channels (TWRCs), where two source nodes A and B exchange their symbols via relay. The sources use the same low-density parity-check (LDPC) code over integer ring $\mathbb {Z}_M$ $M$ -pulse-amplitude modulation, respectively. existing schemes suffer severe rate loss compared with cut-set bound of TWRC, especially low-to-medium signal-to-noise ratio regime. proposed CD-NC can decrease loss. Our contributions are as follows: 1) We develop sum product algorithm (G-SPA) according to principle virtual encoding superimposed symbols. Simulation results show that our achieve significant performance gains conventional both additive white Gaussian noise fading channels; 2) exploit two-dimensional fast-Fourier-transform-based belief propagation (2-D-FFT-BP) extended min-sum (EMS) algorithms reduce complexity G-SPA. 2-D-FFT-BP has G-SPA, while EMS greatly G-SPA at cost slight degradation.