Multi-PRF Waveform Design for Integrated Sensing and Communication System With Range Ambiguity

In this correspondence, we focus on the range ambiguity in the integrated sensing and communications (ISAC) system, which leads to large errors for target ranging. Firstly, we construct transmitted signals with multiple pulse repetition frequencies (multi-PRF) by changing the number of communication symbols across multiple coherent processing intervals (CPIs).This approach is based on the full-duplex ISAC nodes, which sequentially transmit sensing signals and communication symbols within each pulse repetition interval (PRI). Then, we formulate the power allocation problem in the proposed system by maximizing the sensing signal-to-interference ratio (SSINR) under communication rate constraints and provide a closed-form optimal solution. After equalizing the power of sensing and communication signals, the target can be detected at each PRF. Finally, we use the target's observed delay at each PRF for range ambiguity resolution. Simulation results demonstrate that the proposed system has a larger unambiguous area and is more effective in facilitating the detection of a long-range target in comparison to the existing ISAC systems.