  We consider a downlink multiuser massive MIMO system comprising multiple
heterogeneous base stations with hybrid precoding architectures. To enhance the
energy efficiency of the network, we propose a novel coordinated hybrid
precoding technique, where the coordination between the base stations is aimed
at exploiting interference as opposed to mitigating it as per conventional
approaches. We formulate an optimization problem to compute the coordinated
hybrid precoders that minimize the total transmit power while fulfilling the
required quality of service at each user. Furthermore, we devise a
low-complexity suboptimal precoding scheme to compute approximate solutions of
the precoding problem. The simulation results reveal that the proposed
coordinated hybrid precoding yields superior performance when compared to the
conventional hybrid precoding schemes.
