无小区大规模MIMO系统中免授权随机接入性能分析

Performance analysis for Grant-Free random access in Cell-Free massive MIMO

海量机器类通信(mMTC)是5G网络的典型应用场景之一。以前的工作主要研究在传统蜂窝小区下的海量机器类通信,研究了无小区大规模多输入多输出(MIMO)网络中海量机器类通信的免授权随机接入中的联合检测问题。在该模型中,每个设备向接入点发送唯一的导频序列,接入点(APs)将接收到的信号发送到中央处理单元(CPU)进行集中联合检测。采用了近似消息传递算法(AMP)进行联合用户活跃性检测和信道估计。实验结果表明,无小区大规模MIMO系统可以支持大量的通信设备,解决传统小区间的干扰问题,提供一个增强的覆盖,它在很大程度上优于传统的蜂窝小区。

Massive machine-type communication is one of the typical application scenarios of 5G network.Prior works studied the massive machine-type communication in the traditional cellular cells.We study joint detection in grant-free random access for massive machine-type communication in cell-free massive MIMO system.In this model,each device sends a unique pilot sequence to the APs,and the APs sends the received signal to the central processing unit(CPU)for centralized joint detection.In this paper,approximate message passing algorithm(AMP)is used for joint user activity detection and channel estimation.The experimental results show the cell-free massive MIMO can support a large number of communication devices,solve the problem of intercell interference in traditional cellular cells and provide a enhanced coverage.It is much better than traditional cellular cells.