A dual-function MIMO radar-communication system via waveform permutation

Cooperative transmissions for radar and communication tasks have been recently studied with the goal of addressing the problem of the increasingly crowded RF spectrum. In this paper, we propose a dual-function radar communication (DFRC) system in which the radar platform and radar resources are used for simultaneous target probing and communication symbol embedding. The proposed DFRC system is based on the concept of multiple-input multiple-output (MIMO) in tandem with transmit beamforming where a number of transmit beams, which can be larger than the number of transmit antennas, are formed. We show that the transmit beamforming weight vectors may be designed to achieve transmit processing gain, embed communication symbols intended for a communication receiver, and prevent eavesdroppers from intercepting the communication message. Our proposed method for embedding communication symbols into the MIMO radar emissions is based on changing the order of the orthogonal waveforms along the transmit beams from one pulse repetition period to another. In so doing, the communication symbols are represented by different associations of the orthogonal radar waveforms and transmit beams. We show that high data rate, in the megabits per seconds, is achievable for moderate number of transmit antennas, and is proportional to the factorial of the number of transmit beams. The error probability is analyzed and the bounds on the symbol error rate are derived. We show that changing the number of transmit beams leads to a tradeoff between the data rate and target detection accuracy. Simulation examples are provided for performance evaluation and to demonstrate the effectiveness of the proposed information embedding technique.