In recent years, the integration of sensing and communication has gained significant attention. In this context, the adoption of the multiple-input multiple-output (MIMO)orthogonal frequency division multiplexing (OFDM) dual-functional radar and communication (DFRC) system is promising. However, comprehensive exploration of the MIMO-OFDM DFRC system remains incomplete, particularly concerning beamforming design across various radar transmission modes. To address this gap, this paper investigates the joint design of beamforming and subcarrier allocation for MIMO-OFDM DFRC systems. We formulate an ambiguity function-based radar and communication joint design problem. Subsequently, we propose a solution approach that solves the problem by iteratively solving the beamforming and subcarrier allocation subproblems. Simulations are conducted to assess the efficacy of the proposed design approach. The results demonstrate that our approach can effectively adapt to different radar modes and outperform reference methods.

Although the frequency-modulated continuous-wave (FMCW)-based scheme has been considered a candidate for realizing integrated radar-communication (RadCom) systems, it is limited by low spectral efficiency. Thus, this study proposes a frequency hopping-aided FMCW-based RadCom system along with the corresponding radar detection and communication signal demodulation approaches. The proposed system can significantly improve the transmission rate with slight radar performance degradation. In addition, both the radar and communication subsystems of the proposed RadCom system are analyzed. Consequently, a symbol interleaving approach that can mitigate radar performance degradation is proposed. Furthermore, the interference is shown to not degrade the radar performance significantly because of frequency hopping. However, to address the issue of the interference significantly degrading communication performance, interference avoidance and mitigation approaches using scheduling and interference rejection combining, respectively, are proposed. Simulations are conducted to evaluate the proposed RadCom system. The results validate the analysis and demonstrate that the proposed RadCom system can provide radar detection performance that is almost identical to conventional FMCW radar with a high transmission rate. Furthermore, the results confirm the effectiveness of the proposed interleaving and interference management methods.