TY - GEN
T1 - Joint constellation and code design for the Gaussian multiple access channel
AU - Liang, Yu Chung
AU - Rini, Stefano
AU - Kliewer, Jorg
N1 - Funding Information:
The work of Y-C Liang and S. Rini was funded by the Ministry Of Science and Technology (MOST) under the grant 103-2218-E-009-014-MY2. The work of J. Kliewer was supported in part by the U.S. National Science Foundation under grants CCF-1440001 and ECCS-1711056.
PY - 2018/4/10
Y1 - 2018/4/10
N2 - The joint design of both transmit constellation and low-density parity-check codes (LDPC) for the two-user, symbol-synchronous, binary-input Gaussian multiple access channel is considered. A transmission scheme is proposed to approach the symmetric capacity without the use of time-sharing or rate-splitting by joint decoding of the noisy sum of two LDPC codewords. This scheme relies on an extension of the classic belief propagation (BP) algorithm which allows for the simultaneous decoding of two LDPC codewords. We use a Gaussian approximation (GA) of the message distribution to investigate the convergence of the decoding process and derive a linear programming technique for joint code design. We also implement a superposition modulation scheme to achieve higher rate. This code design is applied to different input constellation choices which attain the symmetric capacity in different SNR regimes. It is shown that, quite surprisingly, in the moderate SNR regime the best performance is obtained by an asymmetric constellation.
AB - The joint design of both transmit constellation and low-density parity-check codes (LDPC) for the two-user, symbol-synchronous, binary-input Gaussian multiple access channel is considered. A transmission scheme is proposed to approach the symmetric capacity without the use of time-sharing or rate-splitting by joint decoding of the noisy sum of two LDPC codewords. This scheme relies on an extension of the classic belief propagation (BP) algorithm which allows for the simultaneous decoding of two LDPC codewords. We use a Gaussian approximation (GA) of the message distribution to investigate the convergence of the decoding process and derive a linear programming technique for joint code design. We also implement a superposition modulation scheme to achieve higher rate. This code design is applied to different input constellation choices which attain the symmetric capacity in different SNR regimes. It is shown that, quite surprisingly, in the moderate SNR regime the best performance is obtained by an asymmetric constellation.
UR - http://www.scopus.com/inward/record.url?scp=85050973627&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85050973627&partnerID=8YFLogxK
U2 - 10.1109/ACSSC.2017.8335656
DO - 10.1109/ACSSC.2017.8335656
M3 - Conference contribution
AN - SCOPUS:85050973627
T3 - Conference Record of 51st Asilomar Conference on Signals, Systems and Computers, ACSSC 2017
SP - 1728
EP - 1732
BT - Conference Record of 51st Asilomar Conference on Signals, Systems and Computers, ACSSC 2017
A2 - Matthews, Michael B.
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 51st Asilomar Conference on Signals, Systems and Computers, ACSSC 2017
Y2 - 29 October 2017 through 1 November 2017
ER -