Robust OFDM integrated radar and communications waveform design based on information theory

An integrated radar and communications system (IRCS) where a monostatic radar transceiver is employed for target classification while simultaneously used as a communications transmitter is considered. The radar combined propagation-target response (joint response of the radar propagation channel and target) and communications channel response are generally frequency selective but the corresponding frequency response functions are not exactly known. In particular, these frequency response functions are only known to lie in an uncertainty class. To ensure the IRCS simultaneously provides acceptable target classification performance and communications rate, a robust orthogonal frequency division multiplexing (OFDM) integrated radar and communications waveform (IRCW) design method is proposed. The approach finds a waveform that simultaneously provides a sufficiently large weighted sum of the communications data information rate (DIR) and the conditional mutual information (MI) between the observed signal and the radar target over the entire uncertainty class. First, the conditional MI and DIR based on the integrated OFDM radar and communications waveform are derived. Then, a robust OFDM IRCW optimization problem based on the minimax design philosophy is developed such that closed-form solution is derived. Finally, several numerical results are presented to demonstrate the effectiveness of the proposed method.

💡 Research Summary

The paper addresses the design of a waveform for an Integrated Radar and Communications System (IRCS) that uses a single monostatic radar transceiver both to classify targets and to transmit communication data. In realistic scenarios the radar‑propagation‑target response (the combined effect of the radar channel and the target) and the communication channel are frequency‑selective and their exact frequency‑response functions are unknown; instead they are known only to belong to prescribed uncertainty sets. The authors therefore formulate a robust waveform design problem that guarantees acceptable performance for both target classification and communication over the entire uncertainty class.

First, the authors derive analytical expressions for two information‑theoretic performance metrics based on an OFDM‑based integrated waveform: (i) the conditional mutual information (MI) between the observed radar signal and the target parameters, which quantifies how much information the radar can extract about the target, and (ii) the data information rate (DIR) of the communication link, which is essentially the Shannon capacity of the OFDM sub‑carriers under additive white Gaussian noise. Both metrics depend on the unknown frequency responses of the radar‑target channel (G(f)) and the communication channel (H(f)).

To handle the uncertainty, a weighted sum objective
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