# A Practical Approach to Deploying a Drone-Based Message Ferry in a Disaster Situation +
###### Abstract
After a large-scale disaster hasoccurred, the message ferry is deployed from the local headquarters (i.e., local government office or disaster response coordinator center) for collecting/delivery of vital information from/to the people in the disaster shelters (i.e., the message ferry flies autonomously to the disaster shelters after deployment). The message ferry also utilizes the LACS synchronization function to communicate with other LACS in close proximity, this allows the message ferry to serve as a link for plural LACSs. The goal of our proposed message ferry is to ensure that there is an urgent restoration of network function and/or to deploy an ICT environment locally while extending the service coverage of LACS. This can be more advantageous in collecting and delivering urgent and vital information in the disaster area. Unlike in previous research [18; 19; 20; 21], the proposed message ferry not only introduced the concept of using drones to carry messages from one location to another. It also focused on the practicality and the actual application and usage of the concept in a real life scenario (i.e., disaster situation). The main contributions of this study are summarized as follows. 1. Firstly, we devise an approach to deploying a drone-based message ferry using LACS in the disaster affected areas in order to achieve urgent restoration of network function in a local context. 2. Secondly, we derive a method to analyze the effective transmission speed that the message ferry can achieve in order to extend the LACS-based service area in a disaster situation. 3. Furthermore, we analyze and confirm the effective transmission speed that is useful in transferring data of various sizes when the message ferry is utilized to transfer data from the local headquarters to each disaster shelter. 4. Finally, we evaluate the performance of the proposed message ferry by conducting an experiment. In the experimentation, we use the LACS prototype and measure the inter-LACS data transfer rate. The measured data transfer rate is utilized to confirm the effective transmission speed of the message ferry in a disaster situation. The results show the overall average inter-LACS data transfer rate for a data size of 1 MB, 5 MB, 10 MB, 50 MB, 100 MB and 300 MB and an achievable overall average data transfer rate of 4 Mbps, 14 Mbps, for 802.11 b, g, on a frequency band of 2.4 GHz. In contrast, an overall average of 23 Mbps, 68 Mbps, and 141 Mbps is achievable for 802.11 a, n, ac on the 5 GHz frequency band. In addition, it was confirmed that it is more advantageous to transfer large data size at high data rate. The proposed message ferry achieved a higher effective transmission speed when Wi-Fi IEEE 802.11 protocols are utilized to extend the LACS-based services in the disaster area compared to other technologies such as Wi-SUN [22] and LoRa [23]. An effective transmission speed of 1 Mbps, 1.8 Mbps, 2 Mbps, 2.2 Mbps, and 2.3 Mbps at a distance of 10 km on 802.11 b, 802.11 g, 802.11 a, 802.11 n, and 802.11 ac respectively compared to 25 kbps for Wi-SUN and 119 kbps for LoRa for the same distance. The rest of this paper is organized as follows. Section 2 highlights the features, uses of LACS under various scenarios and presents the use of LACS in the system for collecting and delivering information. Section 3 outlines the proposed drone-based message ferry used to expand the coverage distance of the LACS-based service. In Section 4, we describe the performance evaluation of the proposed message ferry and the analysis of the coverage distance in a disaster affected area. Section 5 concludes the entire paper.