# Communication Technologies in Emergency Situations
## 5 Discussion
### Future Work Directions
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Works Ref.** & **Technologies** & **Communication System** & **Communication Layer** & **Requirements** \\ \hline
[48] & 3 GPP standard, PS-LTE, UAV cloudlets, SDN, edge computing & SR, CIRS, WS & Sensor + Access + Middleware & Rapid deployment, Robustness and reliability, Voice and Data support, Scalability, Security \\ \hline
[49] & Fog computing, Movable BS, Wireless Network & SR & Sensor + Access + Middleware & Rapid deployment, Robustness and reliability, Scalability, Mobility \\ \hline
[50] & Drone Small Cells, Reinforcement Learning (SD) & SR & Sensor + Access & Rapid deployment, Robustness and reliability, Scalability, Mobility \\  & positioning and power allocation) & SR & Sensor + Access & Rapid deployment, Robustness and reliability, \\ \hline
[51] & UAVs-enabled air-ground collaborative & SR & Sensor + Access & Rapid deployment, Robustness and reliability, Scalability, Mobility \\  & emergency network, Aerial Mobile Base Stations & & & Scalability, Mobility \\ \hline
[52] & Satellite Coreellation Network & CIRS, SR & Access & Rapid deployment, Robustness and reliability \\ \hline
[53] & Drones Small Cells, Mobile & SR & Access & Rapid deployment, Robustness and reliability \\ \hline
[54] & Name Data Networking, Edge Computing & SR & Sensor + Access + Middleware & Robustness and reliability, mobility \\ \hline
[55] & Relay network, LTE-A, MIMO textile technology & SR & Sensor + Access & Rapid deployment, Robustness and reliability, Voice and data support \\ \hline
[56] & UAV-BSs & SR & Sensor + Access & Rapid deployment, Robustness and reliability \\ \hline
[57] & UAV-BSs, Satellite LEO & SR, CIRS, WS & Access & Rapid deployment, Robustness and reliability, Voice and data support \\ \hline
[58] & Drones MANET, IoT & SR & Sensor + Access & Rapid deployment, Robustness and reliability \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Cont. The International Telecommunication Union defined a layered model for a Ubiquitous Sensor Network [59]. This layered model is composed of four different components (i.e., sensor networking, access networking, middleware, and applications) and enables practitioners to naturally position a technology in its corresponding component(s), which, at the same time, eases the compatibility and interactions with other layers. This four-layer hierarchical approach could be used as a reference mode to organize and architect communication technologies for emergency situations. More specifically, these are:  
* Sensor networking. This layer includes all the technologies aimed at enabling communications between in-field FRs (or even humans to be rescued). At this layer, the communication requirements share several similarities with those found at the sensing layer of Internet of Things domains. That is: short range, robustness, reduced size and power consumption, low bandwidth (i.e., mostly voice), real-time (i.e., few milliseconds). * Access networking. This layer includes all the technologies aimed at enabling communications between FRs and CIRS. At this layer, the communication requirements increase due to the fact that (1) all in-field data need to be aggregated and (2) critical information to properly manage the emergency needs to be reported--that is, medium range, reliable, medium bandwidth, flexibility, and near real-time (i.e., few hundreds of milliseconds). As this layer is committed to digitally link locations where there is no communication network (or the network has been destroyed itself due to the disaster), the ad-hoc networks composed of UAVs (see Section 4) can result in a convenient approach at this stage. * Middleware. This layer includes all the technologies aimed at enabling communications between different CIRSs. Compared to the access networking layer, at this point, the communication requirements are somehow different. In fact, each CIRS can operate autonomously for a moderately long period of time.