Waveform design for a dual-function radar-communication system based on CE-OFDM-PM signal

Owing to the exponentially increasing spectrum demand for commercial communication, radar and communication are increasingly encouraged to share spectrum. One approach is to incorporate information bearing communication sequences into radar waveforms. However, the varying radar/communication waveforms in a coherent processing interval lead to a range sidelobe modulation (RSM) that cause a loss of coherence when the Doppler processing operation is applied, thus leading to reduced target visibility. In this study, a new approach of embedding communication into radar waveform is proposed. Based on the scheme of constant envelope orthogonal frequency division multiplexing phase modulation (CE-OFDM-PM) and the orthogonality among trigonometric function, information bearing sequences are implemented using CE-OFDM-PM signal and then phase attached to a radar modulation term with a weighted coefficient. Also, the radar modulation term is synthesised by multiple sinusoidal functions where the coefficients of each sinusoidal modulation function are generated using random variables to achieve a thumbtack-like ambiguity function. The weighted coefficient of a communication modulation term provides a direct control of the degree of RSM. Theoretic analysis and simulation results show that a satisfactory communication bit error rate performance can be achieved without sacrificing the radar performance.