Sparse Activity Detection in Multi-Cell Massive MIMO Exploiting Channel Large-Scale Fading

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