Optimal Feedback Bit Allocation for MU-MIMO Systems Combined With OFDM in Cellular Networks

In this correspondence, we investigate the performance of multiuser multiple-input and multiple-output (MU-MIMO) systems in cellular networks using Poisson point process (PPP) models. Focusing on limited-feedback-based MU-MIMO combined with orthogonal frequency division multiplexing (OFDM), we aim to maximize the sum rate of users in wide-band cellular networks. To achieve this, we formulate a centralized feedback bit allocation problem and propose an approximation for the instantaneous signal-to-interference-plus-noise ratio (SINR), as it is difficult to obtain accurately at the transmitter. Using Karush-Kuhn-Tucker (KKT) conditions, we derive closed-form solutions for optimal feedback bit allocation. Our results demonstrate significant performance improvements compared to conventional equal feedback bit allocation, providing practical insights for enhancing the spectral efficiency of wideband communication systems in cellular networks.