Underwater Detection and Communication Integrated Waveform Design Based on P4 Encoding

Affine Frequency Division Multiplexing (AFDM) has emerged as a promising waveform for integrated underwater detection and communication (IUDC) due to its low computational complexity and robust sensing capabilities. This paper investigates AFDM-based underwater systems, focusing on the impact of signal coding on detection performance through the discrete wideband ambiguity function (WAF). An enhanced P4 coding scheme is proposed, incorporating random phase perturbations optimized via particle swarm optimization (PSO) to improve the WAF properties. The proposed method effectively enhances detection performance by significantly reducing sidelobe levels compared to conventional P4 coding, as demonstrated through simulations. Furthermore, the approach maintains reliable communication with minimal bit error rate degradation. By adjusting the maximum phase perturbation, the method offers a flexible trade-off between detection and communication performance, providing a robust and efficient solution for underwater sensing and data transmission.