This paper investigates the energy efficiency of massive unsourced random access~(URA) in multiple-input multiple-output quasi-static Rayleigh fading channels. Specifically, we derive achievability and converse bounds on the minimum required energy-per-bit under the per-user probability of error constraint, where the converse bounds contain two parts: one is general and the other is a weaker ensemble bound. Numerical evaluation shows that the gap between our achievability and converse bounds is less than $5$~dB in the considered regime. Some practical schemes are energy-inefficient compared with our bounds especially when there are many users. Moreover, we observe that in contrast to the sourced random access paradigm, the URA paradigm achieves higher spectral efficiency.
翻译:本文调查了大量无源随机存取~(URA)在多个投入多输出多输出半静态Rayleigh淡化渠道中的能源效率。 具体地说,我们从每个用户的误差概率限制下的最低所需能源- 位数中得出了可实现性和反向界限。 反向界限包含两个部分: 一个是一般的,另一个是较弱的组合。 数字评价表明,在考虑的制度中,我们的可实现性和反向界限之间的差距不到5美元 ~ dB 。 一些实用计划与我们的界限相比是节能的,特别是在有许多用户的情况下。 此外,我们观察到,与源随机存取模式相反, URA 范式实现了更高的光谱效率 。