Combined Transmit Antenna Selection and User Scheduling in a Massive MIMO Broadcast System

Multiple-input multiple-output (MIMO) communication systems are largely employed in networks to achieve high spectral efficiency and throughput. In large scale systems like 5G systems, a large scale MIMO (Massive MIMO) is used where a large array of antennas are used at the base-stations(BS). In MIMO systems as the number of users is always many times more than the antennas at BS, scheduling of users is a very important aspect. In a massive MIMO communication system the selection of transmit antenna is also very critical. Here we propose a scheme in which antenna selection at the BS and user scheduling at the receiver side are performed simultaneously. A algorithm based on semi-orthogonal user selection (SUS) is employed for user scheduling. The main goal of the combined antenna selection and user scheduling algorithm is to maximize the sum-rate capacity of the system. In antenna selection the antennas are eliminated from the set of antenna to find finally a set of antennas which transmits the data to the best set of users selected by the SUS algorithm. The overall complexity of the scheduling scheme reduces as a less complex SUS algorithm is employed for user selection. The performance of our scheme is compared to another scheme where a more complex SUS algorithm is used and from simulation results it is observed that our scheme outperforms the other schemes.