In wireless communication systems, it is important to achieve efficiency and optimize resources while obtaining high data rates and quality of service to users. Massive MIMO systems are part of the solution towards densification of networks, and the optimization of their resources would ensure spectral efficiency. Achievable rate can be optimized in a MIMO system by transmitting with only those antennas with a channel suitable for reliable transmission. This results in a method with better performance for different signal-to-noise ratio (SNR) values. Efficiency is evaluated using the ratio of the achievable rate to the number of transmitting antennas being used for conventional (equal energy) massive MIMO, massive MIMO with WPA and optimized massive MIMO.