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

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 nonbinary symbols via a relay. The two sources use the same nonbinary low-density parity-check (LDPC) c...

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Bibliographic Details
Published in:IEEE transactions on vehicular technology Vol. 68; no. 1; pp. 628 - 640
Main Authors: Chen, Pingping, Shi, Long, Liew, Soung Chang, Fang, Yi, Cai, Kui
Format: Journal Article
Language:English
Published: New York IEEE 01.01.2019
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects:
Algorithms
Binary system
channel decoding
Channels
Codes
Coding
Complexity
Computer simulation
Decoding
Error correcting codes
Modulation
Network coding
Noise propagation
nonbinary LDPC
Parity check codes
Performance degradation
Physical-layer network coding
Pulse amplitude modulation
Random noise
Relay systems
Relays
Signal to noise ratio
Symbols
two-way relay channel (TWRC)
Upper bound
ISSN:0018-9545, 1939-9359
Online Access:Get full text
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Summary: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 nonbinary symbols via a relay. The two sources use the same nonbinary low-density parity-check (LDPC) channel code over the integer ring <inline-formula><tex-math notation="LaTeX">\mathbb {Z}_M</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">M</tex-math></inline-formula>-pulse-amplitude modulation, respectively. The existing channel decoding schemes for nonbinary network coding suffer severe rate loss compared with the cut-set bound of TWRC, especially in the low-to-medium signal-to-noise ratio regime. The proposed CD-NC can decrease the rate loss. Our contributions are as follows: 1) We develop a generalized nonbinary sum product algorithm (G-SPA) for CD-NC according to the principle of virtual encoding of the superimposed symbols. Simulation results show that our CD-NC can achieve significant performance gains over the conventional nonbinary network coding for both additive white Gaussian noise and fading channels; and 2) We exploit two-dimensional fast-Fourier-transform-based belief propagation (2-D-FFT-BP) and extended min-sum (EMS) decoding algorithms to reduce the decoding complexity of G-SPA. Simulation results show that the 2-D-FFT-BP has the same performance as G-SPA, while EMS can greatly reduce the decoding complexity of G-SPA at the cost of slight performance degradation.
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ISSN:0018-9545
1939-9359
DOI:10.1109/TVT.2018.2883509