Energy efficiency, possibly coupled with cognition-based and spectrum-sharing architectures, is a key enabling technology for green communications in 5G-and-beyond standards. In this context, the present paper considers a multiple-input multiple-output communication system cooperatively coexisting with a surveillance radar: the objective function is the communication system energy efficiency, while radar operation is safeguarded by constraining the minimum received signal-to-disturbance ratio for a set of range-azimuth cells of the controlled scene, and no time synchronization between them is assumed. The degrees of freedom are the transmit powers of both systems, the space-time communication codebook and the linear filters at the radar receiver. The resulting optimization problem is non-convex, due to both the objective function and the presence of signal-dependent interference (clutter): we develop a block-coordinate-ascent approximate solution, and offer a thorough performance assessment, so as to elicit the merits of the proposed approach, along with the interplay among the achievable energy efficiency, the density of scatterers in the environment, and the size of the set of protected radar cells.

翻译：能源效率,可能与基于认知和频谱共享结构相结合,是5G和超越标准的一种关键绿色通信赋能技术。在这方面,本文件认为多投入多产出通信系统与监视雷达合作共存:目标功能是通信系统能源效率,而雷达操作则通过限制受控场一组测距电波细胞的最低接收信号-震动比率来加以保障,而且不假定它们之间的时间同步。自由程度是两个系统的传输能力、空间-时间通信代码簿和雷达接收器的线性过滤器。由此产生的优化问题是非电离层,因为其客观功能和存在依赖信号的干扰(断层):我们开发一个区坐标中心近似解决方案,并提供透彻的性能评估,以便了解拟议方法的优点,同时了解可实现的能效、环境中撒散器密度以及受保护雷达电池的大小之间的相互作用。