Quasi-static fading MAC with many users and finite payload

Kowshik, Suhas S; Polyanskiy, Yury

doi:10.1109/isit.2019.8849781

Cited by 29 publications

(27 citation statements)

References 25 publications

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“…In the literature, very few bounds have been developed for multi-user fading channels of short blocklengths. In the insightful analysis of [3], the performance bounds of Rayleigh faded MAC are derived and compared to that of orthogonal e.g., time-division multiple access (TDMA). Since NOMA is deemed to be able to approach MAC bounds, these preliminary new bounds reveal the promising potential of NOMA for massive IoT.…”

Section: A Performance Bounds Of a Multiple Access Channel Having Short Block Lengthmentioning

confidence: 99%

“…Over the last few years, NOMA assisted massive IoT has been a hot research topic [2]. From an information theoretic viewpoint, the fundamental potential of NOMA in supporting massive IoT was analyzed in [3], where the preliminary bounds were derived to show a significant gain for NOMA over orthogonal multiple access (OMA). Channel coding or NOMA is also emerging [4][5], which enriches the study in both fields of channel coding and signal processing.…”

Section: Introductionmentioning

confidence: 99%

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NOMA for Next-Generation Massive IoT: Performance Potential and Technology Directions

Yuan

Wang

et al. 2021

IEEE Commun. Mag.

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Broader applications of the Internet of Things (IoT) are expected in the forthcoming 6G system, although massive IoT is already a key scenario in 5G, predominantly relying on physical layer solutions inherited from 4G LTE and primarily using orthogonal multiple access (OMA). In 6G IoT, supporting a massive number of connections will be required for diverse services of the vertical sectors, prompting fundamental studies on how to improve the spectral efficiency of the system. One of the key enabling technologies is non-orthogonal multiple access (NOMA). This paper consists of two parts. In the first part, finite block length theory and the diversity order of multi-user systems will be used to show the significant potential of NOMA compared to traditional OMA. The supremacy of NOMA over OMA is particularly pronounced for asynchronous contention-based systems relying on imperfect link adaptation, which are commonly assumed for massive IoT systems. To approach these performance bounds, in the second part of the paper, several promising technology directions are proposed for 6G massive IoT, including linear spreading, joint spreading & modulation, multi-user channel coding in the context of various techniques for practical uncoordinated transmissions, cell-free operations, etc., from the perspective of NOMA.

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Section: A Performance Bounds Of a Multiple Access Channel Having Short Block Lengthmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

NOMA for Next-Generation Massive IoT: Performance Potential and Technology Directions

Yuan

Wang

et al. 2021

IEEE Commun. Mag.

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“…However, the authors focused on joint decoding error probability and typicality-based decoders. The authors of [20] studied a similar problem to that in [19] but when the number of users K grows linearly with the number of c.u. n, i.e., K = µn where µ is the user density.…”

Section: Multi-user Finite Block-length: State Of the Artmentioning

confidence: 99%

“…The second idea that relies on an information theory view considers that one packet is transmitted within a small number of channel uses (typically less than few hundreds). Under this assumption, the classical asymptotic regime used in information theory (e.g., [23,24,31]) does not hold, and the finite block-length regime needs to be used [19][20][21][22]. This constraint increases the difficulty of the mathematical analysis, but it also gives access to the latency versus reliability fundamental trade-off.…”

Section: Model and Parametersmentioning

confidence: 99%

Fundamental Limits of Non-Orthogonal Multiple Access (NOMA) for the Massive Gaussian Broadcast Channel in Finite Block-Length

Gorce

Mary

Anade

et al. 2021

Sensors

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Superposition coding (SC) has been known to be capacity-achieving for the Gaussian memoryless broadcast channel for more than 30 years. However, SC regained interest in the context of non-orthogonal multiple access (NOMA) in 5G. From an information theory point of view, SC is capacity-achieving in the broadcast Gaussian channel, even when the number of users tends to infinity. However, using SC has two drawbacks: the decoder complexity increases drastically with the number of simultaneous receivers, and the latency is unbounded since SC is optimal only in the asymptotic regime. To evaluate these effects quantitatively in terms of fundamental limits, we introduce a finite time transmission constraint imposed at the base station, and we evaluate fundamental trade-offs between the maximal number of superposed users, the coding block-length and the block error probability. The energy efficiency loss due to these constraints is evaluated analytically and by simulation. Orthogonal sharing appears to outperform SC for hard delay constraints (equivalent to short block-length) and in low spectral efficiency regime (below one bit per channel use). These results are obtained by the association of stochastic geometry and finite block-length information theory.

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“…2], since P (n) e → 0 only if E n → ∞ (see Lemma 1 ahead). Remark 2: Many works in the literature on many-access channels, including [4], [5], [10]- [13], consider a peruser probability of error…”

Section: Remarkmentioning

confidence: 99%

Capacity per Unit-Energy of Gaussian Random Many-Access Channels

Ravi

Koch

2020

2020 IEEE International Symposium on Information Theory (ISIT)

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This paper considers a Gaussian multiple-access channel with random user activity where the total number of users n and the average number of active users k n may grow with the blocklength n. For this channel, it studies the maximum number of bits that can be transmitted reliably per unit-energy as a function of n and k n. When all users are active with probability one, i.e., n = k n , it is demonstrated that if k n is of an order strictly below n/ log n, then each user can achieve the single-user capacity per unit-energy (log e)/N 0 (where N 0 /2 is the noise power) by using an orthogonal-access scheme. In contrast, if k n is of an order strictly above n/ log n, then the users cannot achieve any positive rate per unit-energy. Consequently, there is a sharp transition between orders of growth where interference-free communication is feasible and orders of growth where reliable communication at a positive rate per unit-energy is infeasible. It is further demonstrated that orthogonal codebooks, which achieve the capacity per unit-energy when the number of users is bounded, can be strictly suboptimal. When the user activity is random, i.e., when n and k n are different, it is demonstrated that if k n log n is sublinear in n, then each user can achieve the single-user capacity per unit-energy (log e)/N 0. Conversely, if k n log n is superlinear in n, then the users cannot achieve any positive rate per unit-energy. Consequently, there is again a sharp transition between orders of growth where interference-free communication is feasible and orders of growth where reliable communication at a positive rate is infeasible that depends on the asymptotic behaviours of both n and k n. It is further demonstrated that orthogonal-access schemes, which are optimal when all users are active with probability one, can be strictly suboptimal in general.

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Quasi-static fading MAC with many users and finite payload

Cited by 29 publications

References 25 publications

NOMA for Next-Generation Massive IoT: Performance Potential and Technology Directions

NOMA for Next-Generation Massive IoT: Performance Potential and Technology Directions

Fundamental Limits of Non-Orthogonal Multiple Access (NOMA) for the Massive Gaussian Broadcast Channel in Finite Block-Length

Capacity per Unit-Energy of Gaussian Random Many-Access Channels

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