Unsourced Random Access With the MIMO Receiver: Projection Decoding Analysis

We consider unsourced random access with MIMO receiver – a crucial communication scenario for future 5G/6G wireless networks. We perform a projection-based decoder analysis and derive energy efficiency achievability bounds when channel state information is unknown at transmitters and the receiver (no-CSI scenario). A comparison to the maximum-likelihood (ML) achievability bounds by Gao et al. (2023) is performed. We show that there is a range of parameters where the new bound outperforms the ML bound. The key improvement reason is a new good region induced by the projection decoding rule. Moreover, the transition to projection decoding rule allows for significant dimensionality reduction, which greatly reduces the bound computation time.