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

Abstract

This article considers the massive MIMO unsourced random access problem on a quasi-static Rayleigh fading channel. Given a fixed message length and a prescribed number of channel uses, the objective is to construct a coding scheme that minimizes the energy-per-bit subject to a fixed probability of error. The proposed scheme differs from other state-of-the-art schemes in that it blends activity detection, single-user coding, pilot-aided and temporary decisions-aided iterative channel estimation and decoding, minimum-mean squared error (MMSE) estimation, and successive interference cancellation (SIC). We show that an appropriate combination of these ideas can substantially outperform state-of-the-art coding schemes when the number of active users is more than 100, making this the best performing scheme known for this regime.

Unsourced Random Access with a Massive MIMO Receiver Using Multiple Stages of Orthogonal Pilots

“…Finally, we note that a new scheme called FASURA has been reported in [29] after the submission of this paper. In FASURA, each user transmits a large blocklength signal containing a non-orthogonal pilot and a randomly spread polar code.…”