# Emergency Communication System Based on Wireless LPWAN and SD-WAN Technologies: A Hybrid Approach
## 6 Conclusions--Future Work  
A significant variety of IoT-focused novel wireless communication technologies have been recently applied in communications. Investment in these technologies for the year 2027 is projected to reach the amount of 1463 billion dollars, reflecting their rapid increase in terms of investment. The number of linked IoT devices worldwide is predicted to reach 75 billion by 2025 [60].  
Thus, an Emergency Communication System (ECS) as a network-based system that enables people to exchange information during crises or physical disasters when basic communication options may have collapsed proved to be a quite promising and feasible option. By implementing an autonomous wireless 4G/LTE base station and a LoRa network the purpose of using unconventional and hybrid methods for establishing communication between a specific site and the outside world is achieved as the combination of communication technologies can allow researchers to improve and develop open-source ECS over conventional architectures. As the LoRa-based wireless network was simulated on the Network Simulator 3 (NS3) using the LoRaWAN open-source module for the NS3, the simulation outcome following the practical implementation allowed firm and sufficient data transfer, providing trustful communications between LPWAN sensor nodes and a LoRa gateway. The proposed scheme provided low data losses by optimizing the installation of the gateway within the premises, while on the other hand the SD-WAN scheme that was simulated on the MATLAB simulator and the LTE Toolbox, in conjunction with an ADALM PLUTO SDR device, proved as well to be an outstanding alternative communication solution with no bit errors measured after recombining all received data blocks. With a zero BER, the simulation tool showed that a LOS one-base station SD-WAN architecture manages data transmission without any errors, thus providing a reliable and robust communication network alternative beyond well-established normal telecommunication networks.  
In the future, we are going to focus on ECS development. We will continue working on systems improvement by adding more base stations and testing a private VoIP application. This methodology will allow us to make accurate conclusions about ECSs for emergencies and off-grid industrial and critical infrastructures. At the same time, we will continue using simulation tools such as NS3, Omnet++, and MATLAB to compare and improve cellular networks by analyzing the RF propagation and the RSSI of our case studies. The next goal is to conduct experiments inside industrial buildings and large infrastructures. Considering the outcomes, we will compute the exact specific number and the positions of the on-premises cellular base stations needed to cover a functional ECS for VoIP applications. Finally, as soon as we overcome some virtualization and slicing management challenges [45], we aim to enable 5G technologies in our architecture to achieve end-to-end latency on the order of 1 ms. After the VoIP application evaluation [46; 47], and the 5G implementation, we will be ready to present a cost-effective solution that employs VoIP communication in embedded systems. As a safe, secure, and easy-to-deploy communication network, it could be used as an ECS in emergencies, in industry, and by the army.  
Conceptualization, V.C., N.P., S.D. and S.P.; methodology, V.C.; software, V.C. and N.M.; validation, V.C., N.P., N.M., S.D. and S.P.; formal analysis, V.C., N.P., S.D. and S.P.; investigation, V.C.; resources, V.C., N.M., N.P., S.D. and S.P.; data curation, V.C. and N.P.; writing--original draft preparation, V.C., N.P., S.D. and S.P.; writing--review and editing, V.C. and N.P.; visualization, V.C., P.P. and D.P.; supervision, P.P. and D.P. All authors have read and agreed to the published version of the manuscript.