Cooperative Interferometric Receiver With Time-Agile Radar Sensing and Radio Communication Capability

A cooperative radar-communication (RadCom) system architecture employing a multiport interferometer receiver is introduced and demonstrated for low-power and low-cost multifunction wireless applications. The proposed system operates in both radar sensing and radio communication modes, which are arranged in different time slots within a single hardware platform. In the radar sensing cycle, a triangular frequency-modulated continuous-wave (FMCW) scheme is adopted for distance and velocity measurements. The radio cycle following the radar sensing cycle is used to communicate beat frequency information among different measurement stations for a cooperative radar operation, which can also be used for other data transmissions. The interferometric receiver for a unified multifunction operation benefits from the cooperative approach as it does not require a receiver front-end with a high dynamic range. The receiver architecture also makes use of a balanced detection scheme to suppress the frequency mixing components generated between radar echoes and cooperative radar responses, which eliminates undesired interferences and false targets as well as to enhance the signal quality. A mathematical model of the proposed sensing system is derived to design and implement the system for operation in a multistation environment. The system performance consisting of two stations in a low microwave frequency band has been established and evaluated for both modes with several experiments. In radar sensing mode, the distance and velocity measurements demonstrate the target finding capability of our proposed system. In radio mode, the demodulation of various digitally modulated signals has been successfully studied at different data rates.