# Communication Technologies in Emergency Situations
## 4 Emergency Communications Technologies--A Systematic Literature Review
### Communication Technologies Integration
It is also observed from the experiment that the maximum hop distance for the prototype is 280 m and 290 m for a Wi-Fi configuration following IEEE 802.11n and IEEE 802.11 ac protocol, respectively. Space Communication Technologies  
Even if Aerial Wireless Networks could be complementary to any other communication technology, there are, of course, still many research works completely focused on other emergency communications. For example, space communications are indeed an important focus of research. Ref. [39] describes the performance of tethered balloon technology as one of the space technologies for public and emergency communications. It focuses on the analysis of the optimal performance of proposed technology for delivering services to rescue and relief teams in emergency situations. The results show that rescue and relief teams are given high priority for performing their duty effectively and efficiently, and their ability to evaluate the performance of the proposed technology, delay, throughput, traffic in both directions, and SNR is considered in testing network performance. Satellite communications are also essential when all the other communications systems are unavailable. An interesting research work on the application and development of a grid of inter-satellite connections and calculation algorithms is proposed in [52]. The main objective is to contribute to the construction of a location-based integrated network communication between satellites and earth, as well as the realization of more efficient space-based information intelligent services. However, since this is the first study on application of the grid system to the interconnection algorithm of low-orbit satellite constellations, there are still many issues worthy of in-depth study. Prioritization and Categorization in ECS  
Another interesting line of research, not so much linked to the communication technology performance but to the need of defining priorities and or categories on the transmissions in emergency situations, is prioritization and categorization in ECS. The following works address this issue from completely different approaches. To satisfy different data transmission requirements and solve the post-disaster problems, ref. [35] proposes a solution for the routing decision problem with multiple QoS constraints based on the Fuzzy Decision Theory (FDT) and the proposed fuzzy-logic-based data-differentiated service supported routing protocol (FDDSP). In this article, the data types are divided into emergency data and regular data. Emergency data require real-time and reliable transmissions, while regular data require a high throughput and balanced energy consumption. FDDSP chooses different Fuzzy Decision Systems to make routing decisions for several types of data and provides differentiated data services to optimize the transmission quality. In [54], they focus on the communication between different emergency response team members. Indeed, when dedicated roles and missions are assigned to responders, role-based communication is a pivotal feature that an emergency communication network needs to support. The authors design and implement a Named Data Networking (NDN)-based disaster response support system over edge computing infrastructure, with KubeEdge as the chosen edge platform to solve the above issues. Their proof-of-concept system performance shows that the architecture achieved efficient role-based communication support, fast mobility handover duration, quick network convergence time in case of node replacement, and loss-free information exchange between responders and the management centre on the cloud. Other Wireless Communication Technologies  
Finally, the following references include other specific works on wireless communications, independent from the categories identified so far.