An Enhanced Fully Decentralized Detector for the Uplink M-MIMO System

Abstract

Decentralized baseband processing (DBP) architectures can alleviate the extremely high interconnect data rates and chip input/output (I/O) bandwidth bottlenecks of the conventional centralized massive multiple-input multiple-output (M-MIMO) system. Nonetheless, fully decentralized (FD) detectors suffer significant performance loss compared with the centralized counterparts due to the constrained information-sharing between antenna clusters, especially for systems with a large number of antenna clusters and/or high-order modulation. In this article, we propose an enhanced message-passing-based FD detection method by utilizing an information-lossless factor graph (FG) transformation scheme. As an illustrative example, the expectation propagation (EP) algorithm is considered in this work. In each antenna cluster, the FG is transformed to a less-loopy one and the effective interference of users is suppressed. Based on the message-passing principle of the EP algorithm, we devise an efficient non-linear fusion scheme in the central processing unit (CPU). In addition, a compensation factor accounting for the cluster profile is introduced to mitigate the inaccuracy of message-passing caused by DBP, thus further enhancing the detection performance. Numerical results demonstrate that the proposed enhanced FD detector obtains significantly better performance than the counterpart with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">even</i> lower computational complexity, especially in a large number of antenna clusters and/or high-order modulation scenarios.