FASURA: A Scheme for Quasi-Static Massive MIMO Unsourced Random Access Channels

Abstract

Cell-Free Massive MIMO systems aim to expand the coverage area of wireless networks by replacing a single highperformance Access Point (AP) with multiple small, distributed APs connected to a Central Processing Unit (CPU) through a fronthaul. Another novel wireless approach, known as the unsourced random access (URA) paradigm, enables a large number of devices to communicate concurrently on the uplink. This article considers a quasi-static Rayleigh fading channel paired to a scalable cell-free system, wherein a small number of receive antennas in the distributed APs serve devices equipped with a single antenna each. The goal of the study is to extend previous URA results to more realistic channels by examining the performance of a scalable cell-free system. To achieve this goal, we propose a coding scheme that adapts the URA paradigm to various cell-free scenarios. Empirical evidence suggests that using a cell-free architecture can improve the performance of a URA system, especially when taking into account large-scale attenuation and fading.

Energy Efficiency of MIMO Massive Unsourced Random Access with Finite Blocklength

“…Moreover, our bounds provide theoretical benchmarks to evaluate practical schemes. Specifically, among the schemes proposed in [5], [11]- [13], the FASURA scheme in [12] performs the best, but it still exhibits a large gap to our bounds in large K a regime. How to reduce this gap is an interesting topic for the future work.…”

“…, 9, 13, 14] for the tree code. We obtain the average of the probabilities of misdetection Theorem 2 Theorem 3 covariance-based scheme [5] pilot-based scheme [11] FASURA scheme [12] tensor-based scheme [13] Fig. 1: The number of active users versus the energy-per-bit for URA with n = 3200, J = 100 bits, L = 50, ǫ = 0.1 for the tensor-based scheme, and ǫ = 0.025 otherwise.…”

“…The error requirement is the same as that for the covariance-based scheme. 5) The FASURA scheme is evaluated as in [12,Fig. 4].…”

Two-Phase Unsourced Random Access in Massive MIMO: Performance Analysis and Approximate Message Passing Decoder

“…Recently, there is another line of works in [16]- [18] that has investigated the use of massive MIMO in the context of URA. These works have shown great efficiencies in the context of MIMO URA with the quasi-static fading channels.…”

“…The method in [17] extended the work [16], where the multiple stages of orthogonal pilots and an additional successive interference cancellation (SIC) operation are adopted to cope with the user collisions in the pilot phase and enhance the decoding performance. The method in [18] combined the pilot-based method with an additional operation called noisy pilot channel estimation (NOPICE) to re-estimate the channel based on the observed signals in both the pilot and the data phases, and further re-update the estimations of the coded symbols.…”