# An Overview of Emergency Communication Networks
## 5 Sea Ad Hoc Network (SANET)
### Summary of Network Development Status
#### 3.2.3 Hybrid Networks  
Emergency communication networks are typical complex networks, involving a variety of communication technologies. Their network composition is diverse and changes dynamically. As a new type of self-organizing wireless network, WMN can not only effectively combine with emergency communication methods such as satellites and short-wave, but can also be used as an extension of mobile communication networks and metropolitan  
Figure 9: Network structure of mobile satellite communication. area networks to provide more extensive wireless access coverage and comprehensively improve the quality of emergency communication. At present, WMN has been applied in fire control, water conservancy and flood control, electric power rescue, railway rescue, maritime law enforcement, marine surveillance and assessment, forest fire prevention, and other fields. China Earthquake Administration [102] proposed a seismic emergency field communication system based on satellite and WMN technology. It realized the interconnection between WMN and the rear command center through a multi-hop mesh network, a satellite communication vehicle, and a rear ground fixed communication base station in the disaster area. For a coal mine emergency communication system, [PERSON] [103] proposed an underground disaster relief communication system based on WMN. The system uses the wireless mesh backbone network constructed from several mesh access points, routers, and gateways as the network architecture, and uses the underground communication function system and ground command center to realize coal mine emergency disaster relief, to meet the needs of a modern mine. Mesh and LTE hybrid networking is widely used in emergency communication because of its advantages such as flexible networking, network robustness, high wireless network bandwidth, support for non-line-of-sight communication, and large network scale. [PERSON] et al. [104] proposed a hybrid networking scheme comprising mesh and LTE networks to address current wireless network capacity shortages, spectrum resource shortages, and application requirements in a particular environment. China Telecom uses a WMN terminal mounted on a low-altitude tethering platform to relay and form a point-to-point wireless back-chain network with multi-point relay and without line-of-sight. Under 5G with high bandwidth and low delay, WMN has more technical advantages, improving the synthesis, application, and systematization. The unique advantages of the ad hoc network enable it to occupy a position in the field of emergency communication. In the future, ad hoc networks will have an ideal space for improvement in miniaturization and portability. In the application of emergency communication, the integration of mesh networks with other private network communication and satellite communication systems will also be the focus of future development. Future development will also include the integration of 5G with satellite networks [105; 106; 107; 108], 5G with UAV integration [109; 110; 111], and the space-ground convergence network [112; 113; 114; 115]. At the moment, the private network projects in the emergency communication industry are gradually shifting from narrowband digital clusters to LTE broadband clusters, and broadband-narrowband integration has also become a significant development direction. A narrowband cluster system is used for comprehensive coverage to achieve voice communication in a wide area, and the 4G-LTE broadband cluster is used to increase range in critical areas. The high bandwidth of the LTE system is utilized to realize video and high-speed data services. 4G private network communication can provide full wireless coverage in a mine, and realize the high-bandwidth wireless integration of voice, data, and video networks, providing a wireless platform for the digitization of coal mines.