论文标题

大规模的毫无用处的随机访问大量的MIMO相关通道

Massive Unsourced Random Access for Massive MIMO Correlated Channels

论文作者

Xie, Xinyu, Wu, Yongpeng, Gao, Junyuan, Zhang, Wenjun

论文摘要

本文调查了配备大量天线的基站(BS)提供大量用户设备的大量随机访问。我们考虑了一个无赠款的无源随机访问(U-RA)方案,其中所有用户都拥有相同的代码簿,而BS旨在宣布发送的代码字列表并恢复主动用户发送的消息。大多数现有作品都集中在过度简化的独立和相同分布(I.I.D.)渠道中应用U-RA。在本文中,我们考虑了一个相当普遍的联合相关的MIMO频道模型,该模型具有现实户外无线传播环境的视线组件。我们通过使用贝叶斯学习自动机进行改进的坐标下降方法来进行发射的代码字活动,以解决基于协方差的最大似然估计问题。所提出的算法比传统下降方法表现出更快的收敛速率。我们进一步采用耦合的编码方案来解决一个问题,即通用代码簿的尺寸在实用的大型机器型通信方案中以用户有效载荷大小为成倍扩展。我们的模拟表明,要实现相关通道中可靠通信的错误概率为0.05,必须支付0.9至1.3 dB的罚款,与I.I.D所需的最小信号与噪声比相比。条件下,BS配备了足够数量的接收天线。

This paper investigates the massive random access for a huge amount of user devices served by a base station (BS) equipped with a massive number of antennas. We consider a grant-free unsourced random access (U-RA) scheme where all users possess the same codebook and the BS aims at declaring a list of transmitted codewords and recovering the messages sent by active users. Most of the existing works concentrate on applying U-RA in the oversimplified independent and identically distributed (i.i.d.) channels. In this paper, we consider a fairly general joint-correlated MIMO channel model with line-of-sight components for the realistic outdoor wireless propagation environments. We conduct the activity detection for the emitted codewords by performing an improved coordinate descent approach with Bayesian learning automaton to solve a covariance-based maximum likelihood estimation problem. The proposed algorithm exhibits a faster convergence rate than traditional descent approaches. We further employ a coupled coding scheme to resolve the issue that the dimensions of the common codebook expand exponentially with user payload size in the practical massive machine-type communications scenario. Our simulations reveal that to achieve an error probability of 0.05 for reliable communications in correlated channels, one must pay a 0.9 to 1.3 dB penalty comparing to the minimum signal to noise ratio needed in i.i.d. channels on condition that a sufficient number of receiving antennas is equipped at the BS.

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