# Emergency Communication System Based on Wireless LPWAN and SD-WAN Technologies: A Hybrid Approach
## 2 Related Work
The outcomes of this implementation demonstrated that a higher spreading factor enhances PDR performance, extending the range of the transceivers. Moreover, they showed that transceiver PDR performance deteriorates when increasing the hop count. Thus, a point-to-point transmission is preferable. To reduce the material cost and loss of lives caused by fires, [PERSON] et al. [14] proposed an ECS for instant fire detection through smoke or gas sensing. They have implemented an outdoor Sigfox-based communication system, as Sigfox among LPWAN is a provider thatcommercializes IoT solutions through partnerships including various network operators. An outdoor application requires long-range connectivity and low power consumption, so they used devices that allow a longer battery life. Their system manages a sleep mode option for energy-saving and data processing. A solar panel charges the system's battery while providing energy on cloudy days. Two sensors are responsible for sensing temperature and smoke, and an Arduino board, an MP3 shield, and a GSM shield are taking over the automated mobile call implementation. Therefore, a Sigfox backend system, away from the monitoring area, will be generated by an emergency alert. In general, this solution is a valid proposal for any researcher who wants to develop an easily-integrated low-budget IoT solution. Besides the LoRaWAN applications, SD-WAN networks can give solutions to a wide range of critical and emergency events. [PERSON] et al. [15] worked on instructions about developing an earthquake early warning system. They conducted some experiments to assess the system latencies and compare the decentralized earthquake early warning (EEW) design concerning a centralized EEW approach. These scenarios included several hypothetical earthquakes. The results of sixty simulations demonstrated that the ideal alerting conditions are produced with an SD-WAN-based hole-punching architecture enabled by a Transmission Control Protocol (TCP). The outcomes also clearly demonstrated that the decentralized EEW system architecture performs better than the central EEW system architecture, saving crucial seconds. [PERSON] et al. [16] approach SD-WAN from the perspective of whether they can offer security in an Industrial Internet of Things (IIoT). For IIoT devices, remote attacks pose a serious concern, particularly in critical infrastructures. SD-WANs create such secure dedicated networks that there is a reduction in the attack surface of organization devices. Additionally, enabling SD-WANs in the Cloud can reduce the risk of an attacker being able to see the IP addresses of the source and destination nodes as packets pass through the network routers. [PERSON] et al. [17] researched SD-WAN usage during an emergency lack of power communication resources. An emergency communication network is essential to sustain the network (electrical grid) power functionality. Optical fiber networks have many benefits, such as sufficient bandwidth, high reliability, easy maintenance, and anti-electromagnetic interference, and they are preferred for communication networks. However, in case of a disaster, optical cables may not work properly, so there is a significant impact on the reliable operation of a communication network, making the requirement for an immediate emergency network (the SD-WAN) essential. The study concludes that optical fiber utilization efficiency may increase significantly when using an SD-WAN implementation. If an optical cable is damaged, SD-WAN can be used as an emergency link to quickly restore communications services and ensure the uninterrupted operation of a power network. We should mention that big companies such as Nokia, Juniper Networks, Silver Peak, and even Cisco [18] have approached SD-WAN technologies and invested in them. Cisco SD-WAN [18, 19] is a software-defined wide-area network solution offered by Cisco Systems. It simplifies the deployment and management of WAN networks while improving network performance and security.