Transmit Waveform Design for Integrated Wideband MIMO Radar and Bi-Directional Communications

In this work, we propose an integrated MIMO system which performs target tracking and downlink communication, as well as receiving uplink signals from other communication nodes to achieve bi-directional communications. The key to such a system is the constrained joint transmit waveform design, which constitutes the main contribution of this work. Per the practical requirement of waveform design, we introduce a new realistic power constraint, referred to as peak-to-valley-power-ratio control with energy budget (PVRC-EB), to remedy the shortcoming of the traditional energy constraint in terms of the transmit elemental power uniformity control. To realize the integrated function of radar and communication, we formulate two joint transmit waveform designs, which achieve a tradeoff between radar function and downlink communication subject to spectral or spatio-spectral energy constraints for accommodating simultaneous uplink communication. For the first design with only spectral constraint, we derive an efficient algorithm based on successive alternating projection (SAP), with its convergence theoretically being proved to approach a stationary point. For the second design with spatio-spectral constraints, we propose a method, referred to as SAP-ADMM, which incorporates the derived SAP steps into the framework of alternating direction method of multipliers. Numerical results demonstrate the effectiveness of the devised methods and a good balance among the three functions can be achieved.