A tradeoff scheme in multi-user scheduling system with block diagonal geometric mean decompositon

For downlink MU-MIMO systems, The BD-GMD scheme is an optimal precoding scheme. Because the number of simultaneously supportable users of BD-GMD scheme is limited by the minimum of the numbers of transmitting and receiving antennae. In a downlink MU-MIMO system with a large number of users, the base station may choose a subset of users to serve simultaneously in order to maximize the total throughput. However, the fairness is ignored when some subscribers remain in the "starvation". We introduce a tradeoff scheme 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. And the simulation results show the validity of the proposed strategy.