Massive MIMO: On which Side Should It Be to Achieve the Highest Capacity?

This paper revisits the problem of assessing the different antenna configurations of the massive MIMO from the system capacity point of view. Specifically, it tried to answer the question: On which side should we deploy the larger number of antennas to achieve the highest possible capacity of the system?. Thus, it investigated the effect of increasing the number of antennas of every side of a massive MIMO system, while keeping the other side equipped with a smaller number of antennas. According to the observations of this paper, it is clear that deploying more antennas on the receiving side will allow for higher system capacity compared with the case of using the same number of antennas at the transmitting side.