This paper studies the device activity detection problem in a multi-cell massive multiple-input multiple-output (MIMO) system, in which the active devices transmit signature sequences to multiple base-stations (BSs) that are connected to a central unit (CU), and the BSs cooperate across multiple cells to detect the active devices based on the sample covariance matrices at the BSs. This paper demonstrates the importance of exploiting the knowledge of channel large-scale fadings in this cooperative detection setting through a phase transition analysis, which characterizes the length of signature sequences needed for successful device activity detection in the massive MIMO regime. It is shown that when the large-scale fadings are known, the phase transition for the multi-cell scenario is approximately the same as that in a single-cell system. In this case, the length of the signature sequences required for reliable activity detection in the multi-cell system can be made to be independent of the number of cells through cooperation, in contrast to the case where the large-scale fadings are not known. Further, this paper considers the case in which the fronthaul links between the BSs and the CU have capacity constraints and proposes a novel cooperation scheme based on the quantization of preliminary detection results at the BSs and the reconstruction of the sample covariance matrices at the CU. Simulations show that the proposed method significantly outperforms the scheme of directly quantizing the sample covariance matrices.

翻译：本文研究多细胞大规模多投入多输出产出系统中的装置活动探测问题,在这个系统中,主动装置将签字序列传送给与中央单位(CU)相连的多个基站(BS),而BS则在多个单元格之间开展合作,根据BS的样本共变矩阵检测活动设备。本文表明,通过阶段过渡分析,利用频道在合作检测中大规模衰减的知识的重要性,这是在大型MIMO制度中成功检测设备活动所需的签字序列长度的特点。文件还表明,当大规模淡化为已知时,多细胞假设的阶段过渡与单一细胞系统中的类似。在这种情况下,通过合作,可靠的活动检测活动所需的签字序列长度可以独立于细胞数量,而大型淡化则不为人们所知。此外,本文件还考虑了以下案例,即BSS初步检测模型前位与BS级模型模型前端联系很大,BSS级测试前端测试模型显示BS级测试模型的模型,而BS级系统前端测试模型显示BS级测试模型的模型,而BS级矩阵模型显示BS级模型的模型的模型的深度模型模型模型的模型,从而显示BS级模型的模型。