Adaptive Proportional Fair Scheduling Based on Block Diagonal Geometric Mean Decomposition

The combined block diagonalization and geometric mean decomposition (BD-GMD) is a preceding scheme that is asymptotically optimal for downlink multi-user multiple-input-multiple-output (MU-MIMO) systems. The number of simultaneously supportable users with BD-GMD is limited by the number of transmitting and receiving antennas. In a downlink MU-MIMO system with a large number of users, the base station may select a subset of users to serve in order to maximize the total throughput. However, the fairness is ignored leads to some subscribers\´ "starvation". We introduce proportional fair scheduling schemes (PFS) into the system to guarantee the fairness, and also propose a new scheme. The proposed algorithm updates the adaptive parameters that indicate past channel quality in each time slot. According to the current and past channel information, we can make better multi-user scheduling and improve the system performance while maintaining the users\´ fairness.