# An Overview of Emergency Communication Networks
## 5 Sea Ad Hoc Network (SANET)
### Summary of Network Development Status
#### 3.2.1 370M Narrowband Private Networks  
The 370M narrowband private network was the first narrowband wireless communication network used for emergency command in China. When major disasters occur, there are often \"three noes\", of no power, no network, and no road. In this case, the narrowband private wireless network significantly improves the capability of ensuring communication. China adopted the domestic PDT standard with independent intellectual property rights to build a 370M emergency command wireless communication network, as well as a public network cluster and emergency communication equipment at the rescue site, to meet the demand of daily wireless command scheduling and sudden emergency communication, and finally connect the 370M PDT communication system of the national emergency management department to the Internet. The PDT communication system is deployed as a combination of fixed and mobile networks, with mobile base stations as the main part and fixed base stations as the auxiliary for digital cluster networking. It can be applied in fire protection, earthquake, and other fields to provide communication support for emergency rescue.  
According to communication scenarios and regions, emergency management communication mainly includes two layers: the 370M PDT digital cluster system and the field emergency communication system. The overall network structure is shown in Figure 8. The 370M PDT digital cluster system includes a PDT + LTE broadband-narrowband fusion core network, a fixed base station, a mobile base station, an integrated command and dispatching center, a site emergency communication system, and terminal equipment. The characteristics of the whole communication system are: mobile is the main network and fixed is the auxiliary network; the mobile vehicle-mounted PDT cluster station is closely combined with the fixed PDT broadcast network; the PDT private network, LTE private network, and public network clusters are interconnected and provide unified scheduling. Functionally, the system realizes the integration from traditional voice communication  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Network Technology** & **Advantages** & **Disadvantages** \\ \hline \multirow{4}{*}{Satellite Communication Technology} & Long communication distance and large & The capacity of communication is limited, \\  & coverage area; flexible networking; & the use cost is high, and there are \\  & communication quality is high and & communication blind spots. \\ \hline \multirow{4}{*}{Ad hoc Network Technology} & Flexible networking mode; wide network & \multirow{2}{*}{Suffers from latency and limited} \\  & coverage; self-organizing, self-healing, & \\  & and self-balancing; highly & \\  & reliable and extensible. & \\ \hline \multirow{2}{*}{Mobile Communication Technology} & The communication distance is not & \multirow{2}{*}{The network is unstable.} \\  & restricted, the coverage area is wide, and & \\  & the cost is low. & \\ \hline Wireless Private Network & \multirow{2}{*}{High reliability and high security.} & High cost and small \\ Communication Technology & & communication capacity. \\ \hline \hline \end{tabular}
\end{table}
Table 3: Advantages and disadvantages of different network technologies.  
to voice, data, and multimedia. Technically, it realizes the integration of broadband, narrowband, Internet of Things, wired, and wireless communication. The network structure also realizes the integration of satellite networks, public networks, and private networks. At present, China's emergency management departments are building 370M PDT emergency private network clusters in an orderly manner, but there are also some challenges, mainly including:  
* Interconnecting the 370M PDT wireless cluster private network with the existing analog cluster.
* Connecting the 370M PDT wireless cluster private network to the completed emergency command and dispatching network.