Analysis of sum-rate gain for multiuser MIMO downlink system with limited feedback and feedback resource constraint

An improved scheduling algorithm is proposed for optimizing the sum-rate gain in a multiuser Multiple-Input and Multiple-Output (MU-MIMO) downlink system with limited feedback and Block Diagonalization (BD) precoding. A low bits feedback for user selection is followed by a high bits feedback to improve the system sum-rate capacity. Based on our analysis and the simulation result, it shows that the newly proposed algorithm can be a potential solution to a MU-MIMO downlink system with feedback resource constraint. A key finding is that an extra step with a high bits feedback can increase the system capacity, especially when signal-to-noise ratio is at high value. The performance analysis for the sum-rate gain using the proposed algorithm is presented in detail and is verified by the simulation results.