Green communications with radar spectrum sharing

In this paper, we consider a multiple-input multiple-output communication system and a surveillance radar sharing the same bandwidth. In this coexistence framework, we undertake a joint system design, where, different from previous studies, we adopt the energy efficiency (i.e., the amount of information reliably delivered per unit of consumed energy) as a figure of merit to be maximized at the communication system side. The radar performance is instead safeguarded by imposing a constraint on the minimum signal-to-disturbance ratio for each inspected range-azimuth resolution cell. The degrees of freedom for system optimization are the transmit powers of both systems, the space-time linear communication codebook, and the radar receive filters are the degrees of freedom for joint system optimization. The block coordinate ascent method is used to find an approximate solution to this problem, and a numerical example is provided to show the merits of the proposed design strategy.