Research On Scheduling Algorithms In MU-MIMO System

MIMO and OFDMA have been the key technologies of the fourth generation communication system (4G) because of its high capacity, high spectral efficiency. This paper mainly studies the scheduling algorithm. The algorithm is to choose the reasonable resource allocation method in the process of time, frequency, power, and buffer sharing between multiple users. It can achieve multi-objective optimal use of resources. This article discusses the scheduling algorithm in three directions:OFDMA resource optimization problem, diversity/multiplexing switching algorithm and multi-user selection algorithm.The article studies several OFDMA resource optimization algorithms which are now commonly used. It then introduces the diversity and multiplexing features and analyzes the diversity/multiplexing switching algorithm which is based on Minimum Euclidean Distance. This article also describes several common multi-user selection algorithms in details. The last part presents a user selection algorithm based on the utility function, and an improved per-user normalization pre-coding and rate control (PU2RC) user selection algorithm.The user selection algorithm which is based on the utility function is to comprehensively consider the selected user's channel information, the orthogonal channel information of existing users, as well as the selected user channel gain when selecting users. This algorithm is a reasonable compromise between complexity and system performance and has a high practical value. Improved utility function algorithm reduces the system complexity while maintaining taking advantage of the utility function algorithm.The brute-force method search for the optimal user set, however, is computationally prohibitive. Based on orthogonal codebook, we propose a low complexity user selection algorithm which is suboptimal. We show that the proposed algorithm achieve nearly performance comparing with the total throughput of the brute-force search method through simulation.