# Communication Technologies in Emergency Situations
## 4 Emergency Communications Technologies--A Systematic Literature Review
### Communication Technologies Integration
[33] is a relevant reference, not only because a real pilot is presented (while, in most of the other references, only simulations take place), but also because it considers the integration of many communication technologies (including the existing ones in maritime emergency scenarios, such as AIS). Although most of the works described so far focus on the performance optimization, other identified requirements such as security, standards, or computation capabilities, among others, are also addressed in the literature. The third-generation partnership project long-term evolution (GPP-LTE) broadband standard, for example, is a key enabler for the emergency communication services in public safety (PS) situations. In [48], the authors reviewed the communication services enabl in PS-LTE. The 3 GPP status of various PS-LTE related services such as proximity services, emergency calls, IOPS, public warning system, and mission critical services are presented. They propose a three-layered Disaster Resilient (DR)-PS-LTE architecture that can meet the strict latency requirements by processing essential functions at the edge and can also be centrally managed using SDN functionality and using UAVs cloudlet for distributed processing. Simulation results show that the proposed DR-PSLTE architecture achieved 20 percent less delay and has low energy consumption as compared to conventional centralized computing. In the same line of distributed computing, ref. [49] presents a detailed mathematical model to represent data processing and transmission in an emergency communication fog network, an NP-hard proof for the problem of optimizing the overall delay, and a novel algorithm to minimize the overall delay for wirelessly networked disaster areas (WNDA) that can be run in real-time. They evaluate the systems across various transmission speeds, processing speeds, and network sizes and tested the calculation time, accuracy, and percent error of the systems. Through evaluation, they found that the proposed disaster area adaptive delay minimization (DAADM) algorithm showed to have a reduced overall delay over various network sizes when compared to some conventional solutions. The DAADM had one major advantage over the Genetic Algorithms (GAs), and that was the processing time, which allows the DAADM to be implemented in a real-time system, where a GA solution would take far too much time. Ref. [46] envisions a privacy-preserving federated learning enabled buses-and-drones based mobile edge infrastructure (ppFL-AidLife) for disaster or pandemic emergency communications. The ppFL-AidLife system aims at a rapidly deployable resilient network capable of supporting flexible, privacy-preserving, and low-latency communications to serve large-scale disaster situations by utilizing the existing public transport networks, associated with drones to maximally extend their radio coverage to those hard-to-reach disasters or should-not-close-contact pandemic zones. Finally, in [57], all the three categories--SH, CIRS, and WS--are addressed. A UAV-assisted emergency Wi-Fi network is proposed to expedite the rescue operations by guiding the survivors to the nearest rescue camp location. Here, the Raspberry PI (RPI) development board, mounted on UAV, is considered to form a Wi-Fi chain network over the disaster region. The designed UAV network can do on-site surveillance and transmit the data to the relief centre for better rescue planning and to alert a survivor about the emergency network by designing a captive portal. Furthermore, to extend the Wi-Fi network, an Android-based application is developed by which each smartphone acts as a relay for its neighbour. Three types of field experiments are carried out to evaluate the performance of the designed prototype. It is found from the field results that the Wi-Fi access point mode and user datagram protocol are more suitable for network design as compared to ad-hoc mode and transmission control protocol, respectively.