On LDPC Code Based Massive Random-Access Scheme for the Gaussian Multiple Access Channel

Glebov, Anton; Medova, Luiza; Rybin, Pavel; Frolov, Alexey

doi:10.1007/978-3-030-01168-0_15

Cited by 17 publications

(13 citation statements)

References 13 publications

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“…when the identities/codebooks of active users are apriori unknown. We just mention here that for random access problem, there are a number of low-complexity algorithms that are available [9][10][11][12][13][14][15]. )…”

Section: Introductionmentioning

confidence: 99%

Quasi-static fading MAC with many users and finite payload

Kowshik

Polyanskiy

2019

2019 IEEE International Symposium on Information Theory (ISIT)

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Consider a (multiple-access) wireless communication system where users are connected to a unique base station over a shared-spectrum radio links. Each user has a fixed number k of bits to send to the base station, and his signal gets attenuated by a random channel gain (quasi-static fading). In this paper we consider the many-user asymptotics of Chen-Chen-Guo'2017, where the number of users grows linearly with the blocklength. In addition, we adopt a per-user probability of error criterion of Polyanskiy'2017 (as opposed to classical joint-error probability criterion). Under these two settings we derive bounds on the optimal required energy-perbit for reliable multi-access communication. We confirm the curious behaviour (previously observed for non-fading MAC) of the possibility of perfect multi-user interference cancellation for user densities below a critical threshold. Further we demonstrate the suboptimality of standard solutions such as orthogonalization (i.e., TDMA/FDMA) and treating interference as noise (i.e. pseudo-random CDMA without multi-user detection).

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Section: Introductionmentioning

confidence: 99%

Quasi-static fading MAC with many users and finite payload

Kowshik

Polyanskiy

2019

2019 IEEE International Symposium on Information Theory (ISIT)

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“…Polyanskiy [12] proposed a framework in which communication occurs in blocks of N channel uses, and the task of a receiver is to identify correctly L active users (messages) out of 2 B , with one regime of interest being N = 30, 000, L = 250, and B = 100. Ever since its introduction, there have been several follow-up works [11,[14][15][16][17], extensions to a massive MIMO scenario [18] where the base station has a very large number of antennas, and a discussion on the fundamental limits on what is possible [19].…”

Section: Introductionmentioning

confidence: 99%

Binary Subspace Chirps

Pllaha¹,

Tirkkonen²,

Calderbank³

2021

Preprint

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We describe in details the interplay between binary symplectic geometry and quantum computation, with the ultimate goal of constructing highly structured codebooks. The Binary Chirps (BCs) are Complex Grassmannian Lines in N = 2 m dimensions used in deterministic compressed sensing and random/unsourced multiple access in wireless networks. Their entries are fourth roots of unity and can be described in terms of second order Reed-Muller codes. The Binary Subspace Chirps (BSSCs) are a unique collection of BCs of ranks ranging from r = 0 to r = m, embedded in N dimensions according to an on-off pattern determined by a rank r binary subspace. This yields a codebook that is asymptotically 2.38 times larger than the codebook of BCs, has the same minimum chordal distance as the codebook of BCs, and the alphabet is minimally extended from {±1, ±i} to {±1, ±i, 0}. Equivalently, we show that BSSCs are stabilizer states, and we characterize them as columns of a well-controlled collection of Clifford matrices. By construction, the BSSCs inherit all the properties of BCs, which in turn makes them good candidates for a variety of applications. For applications in wireless communication, we use the rich algebraic structure of BSSCs to construct a low complexity decoding algorithm that is reliable against Gaussian noise. In simulations, BSSCs exhibit an error probability comparable or slightly lower than BCs, both for single-user and multi-user transmissions.

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“…A brief summary of the AWGN-RAC work is as follows: [1] provided bounds on fundamental limits and identified tremendous energy-inefficiency of existing schemes (like slotted ALOHA [5] which is used for the LTE PRACH channel [6]). In [2,3,[7][8][9][10] various (progressively better) practical schemes were proposed, with the latest being within a few dB of the fundamental limits. In [4] the approach of [3] was extended to quasi-static MIMO fading RAC.…”

Section: Introductionmentioning

confidence: 99%

Energy efficient random access for the quasi-static fading MAC

Kowshik

Andreev²,

Frolov³

et al. 2019

2019 IEEE International Symposium on Information Theory (ISIT)

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We discuss the problem of designing channel access architectures for enabling fast, low-latency, grant-free and uncoordinated uplink for densely packed wireless nodes. Specifically, we extend the concept of random-access code introduced at ISIT'2017 by one of the authors to the practically more relevant case of the AWGN multiple-access channel (MAC) subject to Rayleigh fading, unknown to the decoder. We derive bounds on the fundamental limits of random-access coding and propose an alternating belief-propagation scheme as a candidate practical solution. The latter's performance was found to be surprisingly close to the information-theoretic bounds. It is curious, thus, that while fading significantly increases the minimal required energyper-bit E b /N0 (from about 0-2 dB to about 8-11 dB), it appears that it is much easier to attain the optimal performance over the fading channel with a practical scheme by leveraging the inherent randomization introduced by the channel. Finally, we mention that while a number of candidate solutions (MUSA, SCMA, RSMA, etc.) are being discussed for the 5G, the informationtheoretic analysis and benchmarking has not been attempted before (in part due to lack of common random-access model). Our work may be seen as a step towards unifying performance comparisons of these methods.

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On LDPC Code Based Massive Random-Access Scheme for the Gaussian Multiple Access Channel

Cited by 17 publications

References 13 publications

Quasi-static fading MAC with many users and finite payload

Quasi-static fading MAC with many users and finite payload

Binary Subspace Chirps

Energy efficient random access for the quasi-static fading MAC

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