Minimum Number of Antennas Required to Satisfy Outage Probability in Massive MIMO Systems

In practical massive multiple-input multiple-output (MIMO) systems, determining the number of antennas to satisfy different service demands is an important issue. In this letter, in contrast to the traditional method using the Gaussian approximation, we present a novel approach to determine the number of antennas required to at least satisfy pre-specified outage probability requirements. By exploiting the statistical bounds on instantaneous MIMO capacity, we derive the equivalent problem of determining the number of antennas needed to satisfy outage probability constraints. Through solving the equivalent problem, we obtain the minimum number of antennas required under pre-specified outage probability requirements. Analysis and simulation results demonstrate that, in massive MIMO systems, the required minimum number of antennas obtained by the proposed method is more accurate than that obtained by the traditional method.