Performance of Limited Feedback for Best Companion Grouping in Multi-user MIMO System

In this paper, the system-level performance is evaluated for the feedback scheme on the Precoding Matrix Index (PMI) and Channel Quality Indication (CQI), which are required for user selection in the multi-user MIMO system. Our analysis demonstrates that the number of users, the number of selected users, and codebook size are the key factors that govern the performance of the Best Companion Grouping (BCG)-based user scheduling. Accordingly, we have confirmed that the probability of forming the co-scheduled user group is determined by these factors, implying that the number of PMI's and codebook size can be dynamically determined to maximize the average system throughput subject to the given feedback overhead, as the number of users varies in the cell.