## 2 Related Work  
The terrestrial PNT system predominantly uses GNSS, encompassing BDS, GPS, GLONASS, and GALILEO, to provide PNT services, as shown in Figure 1. Ground or aerial vehicles receive satellite messages that include information on time and satellite position. Then, vehicles can calculate their own position with more than four messages using the range measurement principle, allowing for the calibration of local time and the realization of navigation applications. Within the NASA Moon-to-Mars (M2M) architecture, the sub-architecture for CPNT details the specific systems and infrastructure required to meet the M2M objectives [8]. The CPNT sub-architecture scales to support long-term science, exploration, and industrial needs. Although this is not a CPNT based on underwater acoustic networks, it also shows the importance of CPNT and has good results. At first, communication [9], positioning [10], navigation [11], and timing [12] were studied separately. Later, PNT appeared, which considered positioning, navigation, and timing together. [PERSON] [13] studied the Lunar Pathfinder PNT experiment and the Moonlight Navigation Service, analyzing the future of lunar positioning, navigation, and timing technology. However, PNT services rely on GNSS. When GNSS is interrupted, PNT services are not available. So, along came APNT. Distance measurement equipment (DME) is receiving renewed interest due to its ability to support future aviation navigation and surveillance needs. It is one of the main technologies that is being examined by the FAA Alternative Position Navigation and Timing (APNT) [14] program to support the need to provide an alternative to GNSS in a NextGen airspace. [PERSON] [15] has been examining means to improve DME published accuracy, and examines two of the passive ranging systems being studied for APNT [16]. [PERSON] [17] investigates APNT solutions for aerial vehicles for which highly standardized PNT services are required to ensure secure and safe transportation, including solutions proposed by the FAA in North America. Figure 1: Terrestrial PNT System and related applications based on communication, navigation satellites and ground control center. However, currently CPNT services for deep-sea vehicles are provided by separate communication, positioning, and navigation systems, as well as separate synchronous clocks (atomic clocks). In this paper, a new design method and operating mode of CPNT [18] is proposed to overcome the inherent flaws of the current communication/positioning/navigation modes of deep-sea vehicles; meet the actual demands of deep-sea vehicles in real time; achieve high update rates, low power consumption, and high precision positioning and navigation; and be combined with current development trends. In addition, underwater communication involves not only point-to-point communication, but also networking. Acoustic communication networking is a key technology. Its core technologies mainly include network topology design, efficient communication protocols [19], and energy management strategies [20]. Common underwater acoustic network topologies include chain, cluster, and cellular networks [21]. Traditional communication protocols often cannot be directly applied to underwater acoustic networks. Appropriate protocols need to be developed to enhance communication efficiency and reliability. Since underwater nodes have limited power and are difficult to recharge, effective energy management strategies are essential to prolong the network's lifespan. Ref. [22] designed the UW-WiFi network architecture to solve the problem of underwater acoustic networking with limited coverage range and number of nodes. Ref. [23] developed an MAC protocol for this acoustic network to address the issue of various access requirements of different task nodes in channel resources. Ref. [24] designed an underwater distributed and adaptive resource management framework to maximizes network capacity by supporting an increased number of communications in the network.