A Slotted Unsourced Random Access Scheme with a Massive MIMO Receiver

We consider unsourced random access over fading channels with a massive number of antennas at the base station and propose a simple yet energy-efficient solution by dividing the transmission frame into slots where each slot is also divided into pilot and data parts. We utilize non- orthogonal pilot sequences selected based on part of the information bits, and encode the remaining message bits with a polar code for transmission. At the receiver side, we first detect the transmitted pilot sequences by employing the generalized orthogonal matching pursuit algorithm, and utilize a linear minimum mean square error solution to estimate the channel vectors. We perform symbol estimation by maximal ratio combining, and pass the symbol estimates to a single-user polar decoder to recover the data bits with successive cancellation list decoding, along with successive interference cancellation at the end of each iteration. Numerical examples demonstrate that the proposed scheme either outperforms the existing schemes in the literature, or has a lower complexity while achieving a comparable performance.