In this paper, we propose a computationally-efficient method for user equipment (UE)-centric access point (AP) clustering in downlink cell-free multi-input multi-output (MIMO) systems using the regularized zero-forcing (RZF)-based beamforming (BF). The proposed method selects the set of APs used for each UE based only on the average path gain information between UEs and APs. Thus, it does not need a complex calculation of downlink BF matrix for AP clustering. Furthermore, we propose the AP clustering metric for the RZF-based BF, which takes into account the achievable BF gain and spatial interference levels for two extremes cases of RZF that is pure ZF and maximum ratio combining (MRC). This is achieved by utilizing the average path gain information regarding not only the target UE but also its neighbor UEs. This differentiates the proposed method from the conventional ones, and the proposed method can improve the system-level throughput performance. We assume a realistic partial channel state information scenario, and the computer simulation results show the effectiveness of the proposed method compared to the conventional approaches.
Low-Complexity User-Centric AP Clustering Method in Downlink Cell-Free MIMO with Regularized ZF-Based Beamforming
10.10.2023
1280248 byte
Aufsatz (Konferenz)
Elektronische Ressource
Englisch