Multi-antenna Multi-user Clustering for Relay Aided Cellular Massive–MIMO Systems

In this paper, we scrutinize on the enhancement of the sum rate of multi-antenna active users by implementing user clustering to utilize the standby users at a close proximity. A massive antenna array at the BS and maximum-ratio transmission (MRT) linear precoding is implemented in order to realize a massive multiple–input–multiple–output (MIMO) system. Numerical results show an improvement in the users’ spectral efficiency (SE) due to the mitigation of the interference from external cells when using massive–MIMO. Additionally, the residual self–loop interference at the standby users has been proven to have a significant degradation impact on the relayed link and hence the total SE.