SPARCs and AMP for Unsourced Random Access

Abstract

This paper studies the optimal achievable performance of compressed sensing based unsourced random-access communication over the real AWGN channel. "Unsourced" means that every user employs the same codebook. This paradigm, recently introduced by Polyanskiy, is a natural consequence of a very large number of potential users of which only a finite number is active in each time slot. The resemblance of compressed sensing based communication and sparse regression codes (SPARCs), a novel type of point-to-point channel codes, allows us to design and analyse an efficient unsourced random-access code. Finite blocklength simulations show that the combination of AMP decoding, with suitable approximations, together with an outer code recently proposed by Amalladinne et. al. outperforms state of the art methods in terms of required energyper-bit at lower decoding complexity.