# Design of an Underwater Acoustic Waveform and Integrated System for Communication and Detection
## 1 Introduction  
Autonomous unmanned vehicles (AUVs) have been widely used in the fields of geological surveying, geophysical exploration, emergency rescue, and military operations [1, 2, 3, 4]. To carry out diverse tasks, AUVs typically need to be equipped with various devices, including underwater acoustic detection and communication systems, posing challenges in terms of platform miniaturization, power consumption, and signal processing complexity. Communication is used for data exchange, while radar and sonar are typically used for target detection and identification. Typically, communication and detection are performed separately, with separate resources. Despite their differing objectives, they have commonalities in terms of operation, system structure, and signal processing, which make their integration feasible [5, 6, 7]. Communication and detection integration is now an important research direction [8, 9]. Typically, communication and detection systems are designed separately, which can lead to issues such as redundant hardware, low power efficiency, and internal system interference [10, 11]. Integration enables resource sharing, such as withthe use of transducers, software, and hardware, which can reduce system size and power consumption and improve secrecy. Integrated communication and detection technology is mainly divided into four operational systems: time division, frequency division, beam division, and full sharing systems. The time division system executes communication and detection functions separately in different time slots. Its design is relatively simple and easy to implement. Early examples included the Ku-band radar-communication integration system [12], which adopted time division switching to achieve dual functionalities. However, due to the inability to perform communication and detection simultaneously, there is an issue of low resource utilization. The frequency division system processes communication and detection signals separately by dividing different frequency bands, thereby reducing mutual interference between the two. The automotive radar system designed by [PERSON] is a typical example, which allocates frequency bands for communication by utilizing the side lobes of the radar spectrum [13]. However, such systems still face the problem of inadequate spectrum resource utilization. The beam division system integrates communication and detection by partitioning the beam of the array antenna. An integrated communication and detection system proposed by [PERSON] utilizes the main beam for detection and the side lobes of the beam for communication [14]. However, the division of total energy leads to a limited detection range, and there is an issue of interference from the side lobes to the main lobe. The full sharing system simultaneously realizes communication and detection by using a shared waveform, avoiding the division of time, frequency and power resources. [PERSON] employs OFDM to modulate multi-carrier phase coded (MCPC) sequences to realize radar detection and communication simultaneously, and a novel radar detection scheme is proposed to overcome the large autocorrelation side lobes of the received signal introduced by MCPC. Additionally, it introduces a new method that leverages the orthogonality of MCPC sequences to overcome the effects of multipath fading and inter-carrier interference, enabling the system to balance both radar detection and communication performance [15]. Despite the need for careful design of shared waveforms in the full sharing system and the relatively complex signal processing at the receiving end, this method boasts the highest resource utilization efficiency and has gradually become a focal point of research in integrated communication and detection technology. Waveform design is crucial for the full-sharing system [16; 17; 18]. Research on this began with radar. The design of integrated waveforms can be divided into three categories. The first is the superposition of two orthogonal waveforms to perform detection and communication.