A Performance Bound for Maximal Ratio Transmission in Distributed MIMO

This letter derives a theoretical performance bound for maximal ratio transmission in distributed multiple-input multiple-output systems. We first show that the sum signal-to-interference-and-noise ratio (SINR) of ${K}$ users co-scheduled within the same time-frequency resource block is upper bounded by the total number ${M}$ of radio units. The asymptotic equality case provides a low-complexity power control method. We also show that when max-min fairness power control is applied, SINRs become limited to $M^{\prime }/(K+\rho)$ where $M^{\prime } \leq M$ and $\rho $ are channel-statistics-dependent parameters. The simulation results show the effectiveness of the methods in optimizing user spectral efficiencies.