  We consider the uplink of massive multicell multiple-input multiple-output
systems, where the base stations (BSs), equipped with massive arrays, serve
simultaneously several terminals in the same frequency band. We assume that the
BS estimates the channel from uplink training, and then uses the maximum ratio
combining technique to detect the signals transmitted from all terminals in its
own cell. We propose an optimal resource allocation scheme which jointly
selects the training duration, training signal power, and data signal power in
order to maximize the sum spectral efficiency, for a given total energy budget
spent in a coherence interval. Numerical results verify the benefits of the
optimal resource allocation scheme. Furthermore, we show that more training
signal power should be used at low signal-to-noise ratio (SNRs), and vice versa
at high SNRs. Interestingly, for the entire SNR regime, the optimal training
duration is equal to the number of terminals.
