Many-user MAC is an important model for understanding energy efficiency of massive random access in 5G and beyond. Introduced in Polyanskiy'2017 for the AWGN channel, subsequent works have provided improved bounds on the asymptotic minimum energy-per-bit required to achieve a target per-user error at a given user density and payload, going beyond the AWGN setting. The best known rigorous bounds use spatially coupled codes along with the optimal AMP algorithm. But these bounds are infeasible to compute beyond a few (around 10) bits of payload. In this paper, we provide new achievability bounds for the many-user AWGN and quasi-static Rayleigh fading MACs using the spatially coupled codebook design along with a scalar AMP algorithm. The obtained bounds are computable even up to 100 bits and outperform the previous ones at this payload.

翻译：许多用户的MAC是了解5G及以后大规模随机访问的能源效率的重要模式。 在Polyanskiy'2017中为AWGN频道引入了AWGN频道,随后的工程为在特定用户密度和有效载荷以外的特定用户实现每个用户目标错误所需的无线最低能量/比特提供了改进的界限。最著名的严格界限使用空间连接代码和最佳AMP算法。但这些界限无法计算出几(大约10)位有效载荷以外的有效载荷。在本文中,我们为多个用户的AWGN和准静态Rayleigh 提供新的可实现性界限,同时使用空间连接的代码设计以及一个缩放 AMP算法,获得的界限甚至可以计算到100位,并且超过了这一有效载荷上以前的界限。