  The deployment of a large number of small cells poses new challenges to
energy efficiency, which has often been ignored in fifth generation (5G)
cellular networks. While massive multiple-input multiple outputs (MIMO) will
reduce the transmission power at the expense of higher computational cost, the
question remains as to which computation or transmission power is more
important in the energy efficiency of 5G small cell networks. Thus, the main
objective in this paper is to investigate the computation power based on the
Landauer principle. Simulation results reveal that more than 50% of the energy
is consumed by the computation power at 5G small cell BS's. Moreover, the
computation power of 5G small cell BS can approach 800 watt when the massive
MIMO (e.g., 128 antennas) is deployed to transmit high volume traffic. This
clearly indicates that computation power optimization can play a major role in
the energy efficiency of small cell networks.
