Throughput Enhancement for the Joint Radar-Communication Systems Based on Cognitive Closed-Loop Design

The majority of the current dual function radar-communication (DFRC) systems are producing only an angle-dependent transmit beampattern (BP) and imposing a constraint for the communication receiver to be present within the sidelobe (SL) directions to decode the transmitted information. In this paper, an efficient angle-range dependent DFRC system is proposed using frequency diverse array (FDA)-multiple-input multiple-output (MIMO) configuration. We developed a closed-loop design that improves the tracking task of the system and permits a cognitive selection for an optimum signaling strategy towards the intended communication receiver during each scan. We used two information embedding schemes, a proposed amplitude phase shift keying (APSK) and phase-shift keying (PSK), that utilize either the magnitude ratios and/or phase shifts between the radar waveform pairs towards the communication direction. Hence, the communication link is maintained and the system throughput is enhanced. The simulation results verify that the communication performance is enhanced in terms of low symbol error rate (SER), secure information transmission, and increased throughput, while for radar applications the performance is improved in terms of target detection and parameter estimation. It also showed that the proposed symbol mapping APSK scheme provides a high data rate transmission compared to the existing SL-based information embedding schemes while preserving a low bit error rate (BER). Besides, the Cramer-Rao lower bounds (CRLB) for range and angle estimation and the signal-to-interference-noise ratio (SINR) for the proposed DFRC system are analyzed.