Affiliation of Author(s):Beihang University

Teaching and Research Group:202 and 203

Journal:IEEE Transactions on Signal Processing

Place of Publication:US

Funded by:National Key R&D program - 6G agile and efficient waveform and multiple access tec No.2020YFB1807102

Key Words:Coded modulation, lattice codes, physical-layer network coding, compute-forward, network information theory, multiple-access, broadcast channel, dirty paper coding

Abstract:Structured codes based on lattices were shown to provide enlarged capacity for multi-user communication networks. In this paper, we study capacity-approaching irregular repeat accumulate (IRA) codes over integer rings Z_{2^m} for 2^m-PAM signaling, m = 1,2,.. . Such codes feature the structural property that the integer sum of K codewords belongs to the extended codebook (or lattice) w.r.t. the base code. With it, the gains promised in lattice based network information theory can be materialized in practical systems with 2m-PAM signaling. In designing IRA ring codes, we first analyze the effect of zero-divisors of integer ring on the iterative belief-propagation (BP) decoding, and show the invalidity of symmetric Gaussian approximation. Then we propose a doubly IRA (D-IRA) ring code structure, consisting of irregular multiplier distribution and irregular node-degree distribution, that can restore the symmetry and optimize the BP decoding threshold. For point-to-point AWGN channel with 2m-PAM inputs, D-IRA ring codes perform as low as 0.29 dB to the capacity limits, outperforming existing bit-interleaved coded-modulation (BICM) and IRA modulation codes over GF(2m). We then proceed to design D-IRA ring codes for two important multi-user communication setups, namely dirty paper coding (DPC) and compute-forward (CF). With it, a simple linear DPC scheme exhibits a gap to the capacity by 0.91 dB, and a physical-layer network coding scheme yields a gap to the CF limit by 0.24 dB.

Indexed by:Journal paper

First-Level Discipline:Information and Communication Engineering

Document Type:J

Translation or Not:no

Date of Publication:2022-09-29

Included Journals:SCI

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