  In this paper, we aim to design highly energy efficient end-to-end
communication for millimeter wave multiple-input multiple-output systems. This
is done by jointly optimizing the digital-to-analog converter
(DAC)/analog-to-digital converter (ADC) bit resolutions and hybrid beamforming
matrices. The novel decomposition of the hybrid precoder and the hybrid
combiner to three parts is introduced at the transmitter (TX) and the receiver
(RX), respectively, representing the analog precoder/combiner matrix, the
DAC/ADC bit resolution matrix and the baseband precoder/combiner matrix. The
unknown matrices are computed as a solution to the matrix factorization problem
where the optimal fully digital precoder or combiner is approximated by the
product of these matrices. A novel and efficient solution based on the
alternating direction method of multipliers is proposed to solve these problems
at both the TX and the RX. The simulation results show that the proposed
solution, where the DAC/ADC bit allocation is dynamic during operation,
achieves higher energy efficiency when compared with existing benchmark
techniques that use fixed DAC/ADC bit resolutions.
