  Energy efficiency (EE) optimization of millimeter wave (mm-Wave) massive
multiple-input multiple-output (MIMO) systems is emerging as an important
challenge for the fifth generation (5G) mobile communication systems. However,
the power of radio frequency (RF) chains increases sharply due to the high
carrier frequency in mm-Wave massive MIMO systems. To overcome this issue, a
new energy efficiency optimization solution is proposed based on the structure
of the generalized spatial modulation (GSM) and sub-connected hybrid precoding
(HP). Moreover, the computation power of mm-Wave massive MIMO systems is
considered for optimizing the EE. Simulation results indicate that the EE of
the GSM-HP scheme outperforms the full digital precoding (FDP) scheme in the
mm-Wave massive MIMO scene, and 88\% computation power can be saved by the
proposed GSM-HP scheme.
