# An Overview of Emergency Communication Networks
## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Parameter** & **Satellite Communication** & **Ad hoc Network** & **Mobile Communication** & **Wireless Private Network** \\  & **Technology** & **Technology** & **Technology** & **Communication Technology** \\ \hline \multirow{2}{*}{Characteristic} & Using satellites as relays & Peer-to-peer structure & Cellular wireless networking mode & Private network in specific area \\ \hline \multirow{4}{*}{Advantages} & Large communication & Flexible networking, wide & \multirow{2}{*}{\begin{tabular}{c} Overcast, \\ self-organization, self-healing, \\ self-balancing, high network \\ reliability, high scalability \\ \end{tabular} } & Unrestricted distance, wide coverage area, & \multirow{2}{*}{High reliability, high security} \\  & & & self-balancing, high network & \\ \hline \multirow{2}{*}{Disadvantages} & High cost, high & \multirow{2}{*}{\begin{tabular}{c} High latency, limited \\ blind spots \\ \end{tabular} } & High latency, limited & \multirow{2}{*}{\begin{tabular}{c} Unstable, low \\ anti-interference ability \\ \end{tabular} } & High cost, small \\  & & & bandwidth capacity & \\ \hline \multirow{2}{*}{Existing schemes} & VSAT, Immarsat, Starlink, & WMN, MANET, VANET, & \multirow{2}{*}{D2D, 5G, 6G} & PDT, DMR, DPMR, P25 \\  & Tiantong-1, BeiDou & FANET, SANET & & technology, PMR, LTE, TETRA \\ \hline \multirow{4}{*}{Application scenarios} & Personnel positioning, & \multirow{2}{*}{\begin{tabular}{c} Mine emergency rescue, fire \\ enviroment protection, \\ meteorological \\ disaster prediction \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} Minetary field, \\ medical treatment, \\ security, household, \\ transportation, construction \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} Public security, \\ fire protection, rescue, \\ petrochemical, earthquake \\ \end{tabular} } \\  & Miniaturization, low cost, & \multirow{2}{*}{\
\begin{tabular}{c} Miniaturization, low \\ attenuation, low bandwidth, \\ portability, hybrid networks \\ \end{tabular} } & High coverage, high & \multirow{2}{*}{
\begin{tabular}{c} Hybrid networks, \\ uniform standard, \\ fixed-mobile integration, \\ broadband-narrowband \\ integration, public- \\ private complementary \\ \end{tabular} } \\ \hline \hline \end{tabular}
\end{table} 
Table 7: The features of various emergency communication technologies. 16 video signals can be pulled at the same time, ensuring communication for the visual dispatch of emergency rescue services. At present, all countries have recognized the importance of emergency communication networks, and further development has been made in relevant technologies. However, in the new situation, the emergency communication network still faces many problems to be solved:  
* Frequency resources: at present, there is a lack of national disaster communication dedicated spectrum. Effective spectrum management and dedicated disaster spectrum can minimize network congestion after disasters. * Bandwidth limitation: wireless transmission bandwidth is limited, and suffers from signal fading and noise interference. * Security: for information transmission, security services must be provided to enable reliable and secure communication through privacy, authentication, or access control. In an emergency, the deployed wireless communication network may be vulnerable to failures and security threats, resulting in incorrect data. Reliable, secure, and robust communications are therefore critical to successful emergency management operations. * Routing protocol: due to the different mobilities and topologies of different networks, routing paths are prone to interruption. In order to ensure the stability of networks, an efficient routing algorithm is needed. * Network mobility: the nodes of a hybrid network have special mobility. Furthermore, the network topology changes rapidly and ground terminals or ground sub-nets composed of multiple terminals are in constant motion. Therefore, network mobility has gradually become a key factor affecting network performance.