Design of LDPC Codes for the Unequal Power Two-User Gaussian Multiple Access Channel

Balatsoukas‐Stimming, Alexios; Liavas, Athanasios P.

doi:10.1109/lwc.2018.2833855

Cited by 17 publications

(21 citation statements)

References 13 publications

(65 reference statements)

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“…Similarly, it can be shown that the EXIT chart I V S describing the variable-to-state messages is [2], [13]…”

Section: [K]mentioning

confidence: 95%

“…where F [1] 00 and F [1] 01 denote the mean of the state-to-variable messages towards user 1 given the distribution of the channel observation y (see [13]) and the mean m of the (symmetric Gaussian distributed) variable-to-state messages from user 2. The mean m is given by…”

Section: [K]mentioning

confidence: 99%

“…Typically, higher rates can be achieved with higher v max , but the decoding complexity of the LDPC code also increases. As in [13], we fix the variable node degree distribution of one Fig. 3.…”

Section: B Degree Distribution Optimizationmentioning

confidence: 99%

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LDPC Coded Multiuser Shaping for the Gaussian Multiple Access Channel

Balatsoukas‐Stimming

Rini²,

Kliewer³

2019

2019 IEEE International Symposium on Information Theory (ISIT)

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The joint design of input constellation and lowdensity parity-check (LDPC) codes to approach the symmetric capacity of the two-user Gaussian multiple access channel is studied. More specifically, multilevel coding is employed at each user to construct a high-order input constellation and the constellations of the users are jointly designed so as to maximize the multiuser shaping gain. At the receiver, each layer of the multilevel coding is jointly decoded among users, while successive cancellation is employed across layers. The LDPC code employed by each user in each layer is designed using EXIT charts to support joint decoding among users for the prescribed per-layer rate and SNR. Numerical simulations are provided to validate the proposed constellation and LDPC code designs.

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“…Similarly, it can be shown that the EXIT chart I V S describing the variable-to-state messages is [2], [13]…”

Section: [K]mentioning

confidence: 95%

Section: [K]mentioning

confidence: 99%

See 1 more Smart Citation

LDPC Coded Multiuser Shaping for the Gaussian Multiple Access Channel

Balatsoukas‐Stimming

Rini²,

Kliewer³

2019

2019 IEEE International Symposium on Information Theory (ISIT)

Self Cite

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“…Recent works in [34], [35], [36] address LDPC code design with two users applying optimal joint detection and a Gaussian-mixture model to approximate the message probability density function (PDF) at the CNs. In [37], the LDPC codes are optimized for IDMA systems with a relatively large number of users (6 to 10), again with an optimum joint MUD.…”

Section: B Related Workmentioning

confidence: 99%

Near-Capacity Detection and Decoding: Code Design for Dynamic User Loads in Gaussian Multiple Access Channels

Wang

Cammerer

Brink

2019

IEEE Trans. Commun.

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This paper considers the forward error correction (FEC) code design for approaching the capacity of a dynamic multiple access channel (MAC) where both the number of users and their respective signal powers keep constantly changing, resembling the scenario of an actual wireless cellular system. To obtain a low-complexity nonorthogonal multiple access (NOMA) scheme, we propose a serial concatenation of a low-density parity-check (LDPC) code and a repetition code (REP), this way achieving near Gaussian MAC (GMAC) capacity performance while coping with the dynamics of the MAC system. The joint optimization of the LDPC and REP codes is addressed by matching the analytical extrinsic information transfer (EXIT) functions of the sub-optimal multi-user detector (MUD) and the channel code for a specific and static MAC system, achieving near-GMAC capacity. We show that the near-capacity performance can be flexibly maintained with the same LDPC code regardless of the variations in the number of users and power levels. This flexibility (or elasticity) is provided by the REP code, acting as "userload and power equalizer", dramatically simplifying the practical implementation of NOMA schemes, as only a single LDPC code is needed to cope with the dynamics of the MAC system.

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“…LDPC codes with BP decoder are appropriate for implementing by a joint decoder. This approach has been utilized over a two-user GMAC in [19] and [20]. Their proposed joint decoding is described by a two-user Tanner graph which consists of two single-decoders corresponding to the transmitters.…”

Section: Ldpc Joint Decoder Over Gmacmentioning

confidence: 99%

LDPC codes over Gaussian multiple access wiretap channel

2018

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We study the problem of two-user Gaussian multiple access channel (GMAC) in the presence of an external eavesdropper. In this problem, an eavesdropper receives a signal with a lower signal-to-noise ratio (SNR) compared to the legitimate receiver and all transmitted messages should be kept confidential against the eavesdropper. For this purpose, we propose a secure coding scheme on this channel which utilizes low-density parity-check (LDPC) codes by employing random bit insertion and puncturing techniques. At each encoder, the confidential message with some random bits as a random message are systematically encoded, and then the associated bits to the confidential message are punctured. Next, the encoders send their unpunctured bits over a Gaussian multiple access wiretap channel (GMAC-WT). The puncturing distribution applied to the LDPC code is considered in two cases: random and optimized. We utilize a modified extrinsic information transfer (EXIT) chart analysis to optimize the puncturing distribution for each encoder. The security gap is used as a measure of secrecy for the sent messages over GMAC-WT which should be made as small as possible. We compare the achieved secure rate pair with an achievable secrecy rate region of GMAC-WT to show the effective performance of the proposed scheme. In this paper, equal and unequal power conditions at the transmitters are investigated. For both cases, we attain a fairly small security gap which is equivalent to achieve the points near the secrecy rate region of GMAC-WT.

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Design of LDPC Codes for the Unequal Power Two-User Gaussian Multiple Access Channel

Cited by 17 publications

References 13 publications

LDPC Coded Multiuser Shaping for the Gaussian Multiple Access Channel

LDPC Coded Multiuser Shaping for the Gaussian Multiple Access Channel

Near-Capacity Detection and Decoding: Code Design for Dynamic User Loads in Gaussian Multiple Access Channels

LDPC codes over Gaussian multiple access wiretap channel

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