Pilot-Based Unsourced Random Access with a Massive MIMO Receiver in the Quasi-Static Fading Regime

Fengler, Alexander; Jung, Peter; Caire, Giuseppe

doi:10.48550/arxiv.2012.03277

Cited by 5 publications

(10 citation statements)

References 30 publications

(54 reference statements)

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“…In [19], a tensor-based communication scheme was proposed, and both MD and FA probabilities were reported in the performance evaluation. Another scheme for which both MD and FA probabilities have been reported was recently proposed in [20] for the quasi-static fading MAC and for the case in which the receiver has a large number of antennas. However, in [19] and [20], the MD and FA probabilities are not reported separately but rather through their sum.…”

Section: Index Termsmentioning

confidence: 99%

Unsourced Multiple Access With Random User Activity

Ngo¹,

Lancho²,

Durisi³

et al. 2022

Preprint

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To account for the massive uncoordinated random access scenario, which is relevant for the Internet of Things, Polyanskiy (2017) proposed a novel formulation of the multiple-access problem, commonly referred to as unsourced multiple access, where all users employ a common codebook and the receiver decodes up to a permutation of the messages. In this paper, we extend this seminal work to the case where the number of active users is random and unknown a priori. We define a random-access code accounting for both misdetection (MD) and false alarm (FA), and derive a random-coding achievability bound for the Gaussian multiple access channel. Our bound captures the fundamental trade-off between MD and FA probabilities. It suggests that the lack of knowledge of the number of active users entails a small penalty in energy efficiency when the target MD and FA probabilities are high. However, as the target MD and FA probabilities decrease, the energy efficiency penalty becomes more significant. For example, in a typical IoT scenario with framelength 19200 complex channel uses and 25-300 active users in average, the required energy per bit to achieve both MD and FA probabilities below 10 −1 , predicted by our bound, is only 0.5-0.7 dB higher than that predicted by the bound in Polyanskiy (2017) for a known number of active users. This gap increases to 3-4 dB when the target MD probability and/or FA probability is below 10 −3 . Taking both MD and FA into account, we use our bound to benchmark the energy efficiency of slotted-ALOHA with multi-packet reception, of a decoder that simply treats

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Section: Index Termsmentioning

confidence: 99%

Unsourced Multiple Access With Random User Activity

Ngo¹,

Lancho²,

Durisi³

et al. 2022

Preprint

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“…Besides, without requiring a separate activity detection or channel estimation step, A. Decurninge et al introduced a structure that allows the receiver to separate the users using a classical tensor decomposition [24]. As URA is a special scheme of grant-free random access, A. Fengler et al presented a conceptually simple algorithm based on pilot transmission, activity detection, channel estimation, Maximum Ratio Combining (MRC), and single-user decoding [25], which is similar to the existing grant-free random access schemes [3], [18]. The difference is that they use a pool of non-orthogonal pilots where every active user picks one of them pseudo-randomly.…”

Section: B Related Workmentioning

confidence: 99%

“…If the traditional tree decoder fixes a sub-block transmitted by two active users at the first stage, then the decoder finally outputs two valid tree messages. According to [25], we give E{C k,s } as the average number of collisions of k users on consistent s sub-blocks started from the first one, which is written as…”

Section: Beam-space Tree Decoder With Soft Decisionmentioning

confidence: 99%

Unsourced Random Massive Access with Beam-Space Tree Decoding

Che¹,

Zhang²,

Yang³

et al. 2021

Preprint

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The core requirement of massive Machine-Type Communication (mMTC) is to support reliable and fast access for an enormous number of machine-type devices (MTDs). In many practical applications, the base station (BS) only concerns the list of received messages instead of the source information, introducing the emerging concept of unsourced random access (URA). Although some massive multiple-input multiple-output (MIMO) URA schemes have been proposed recently, the unique propagation properties of millimeter-wave (mmWave) massive MIMO systems are not fully exploited in conventional URA schemes. In grant-free random access, the BS cannot perform receive beamforming independently as the identities of active users are unknown to the BS. Therefore, only the intrinsic beam division property can be exploited to improve the decoding performance. In this paper, a URA scheme based on beam-space tree decoding is proposed for mmWave massive MIMO system. Specifically, two beam-space tree decoders are designed based on hard decision and soft decision, respectively, to utilize the beam division property. They both leverage the beam division property to assist in discriminating the sub-blocks transmitted from different users. Besides, the first decoder can reduce the searching space, enjoying a low complexity. The second decoder exploits the advantage of list decoding to recover the missdetected packets. Simulation results verify the superiority of the proposed URA schemes compared to the conventional URA schemes in terms of error probability.

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“…where P 2 is given by (15) and v) The parameter r is called the decoding radius. The decoding radius can be optimized according to the target MD and FA probabilities.…”

Section: Random-coding Boundmentioning

confidence: 99%

“…In [14], a tensor-based communication scheme was proposed, and both MD and FA probabilities are reported in the performance evaluation. Another scheme that addresses both MD and FA probabilities was recently proposed in [15] for the quasi-static fading MAC where the receiver has a large number of antennas.…”

Section: Introductionmentioning

confidence: 99%

Massive Uncoordinated Access With Random User Activity

Ngo¹,

Lancho²,

Durisi³

et al. 2021

Preprint

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We extend the seminal work by Polyanskiy (2017) on massive uncoordinated access to the case where the number of active users is random and unknown a priori. We define a randomaccess code accounting for both misdetection (MD) and falsealarm (FA), and derive a random-coding achievability bound for the Gaussian multiple access channel. Our bound captures the fundamental trade-off between MD and FA probabilities. The derived bound suggests that, for the scenario considered in Polyanskiy (2017), lack of knowledge of the number of active users entails a small penalty in terms of power efficiency. For example, our bound shows that 0.5-0.7 dB extra power is required to achieve both MD and FA probabilities below 0.1 compared to the case in which the number of active users is known a priori. Taking both MD and FA into account, we show that some of the recently proposed massive random access schemes are highly suboptimal with respect to our bound.

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Pilot-Based Unsourced Random Access with a Massive MIMO Receiver in the Quasi-Static Fading Regime

Cited by 5 publications

References 30 publications

Unsourced Multiple Access With Random User Activity

Unsourced Multiple Access With Random User Activity

Unsourced Random Massive Access with Beam-Space Tree Decoding

Massive Uncoordinated Access With Random User Activity

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