LOS/NLOS Based User Grouping Scheduling Algorithm for Downlink Massive MIMO Systems

Massive multiple-input multiple-output (MIMO) system is considered as a key technology in 5G as the users' channel vectors are generally correlated with the number of antennas grows. However, in reality, the users' channel vectors are generally correlated. To achieve the good performance of the massive MIMO system, user grouping and scheduling algorithms are necessary, which separate the highly correlated users. We noticed that users under line-of-sight (LOS) and non-line-of-sight (NLOS) conditions have different characters on the channel correlation and proposed a user grouping and scheduling algorithm based on the users' LOS/NLOS conditions. Different methods are used to grouping and scheduling users with different LOS/NLOS conditions. A correlation criteria with a certain threshold is used for user grouping. The simulation results reveal that the proposed scheme can achieve a significant gain in system throughput.