# A Practical Approach to Deploying a Drone-Based Message Ferry in a Disaster Situation +
## 3 Proposed Drone-Based Message Ferry for LACS Network  
After a disaster that caused damage to the communications infrastructure, there is a critical need to restore it or deploy a substitute ICT network to meet the explosive demand for communication services in the disaster areas. To meet this issue, we proposed LACS as stated above. However, the service area covered by a LACS is limited to about hundred meters in radius at the maximum due to the Wi-Fi characteristics. This can hamper the information collection and delivery of disaster information which is needed for timely disaster recovery and management efforts. To extend the service area, we need ways to form a LACS network by linking plural LACSs distributed in the area. The links based on optical fibers and fixed-wireless-access links are possible candidates, but they need time and occasionally receive restrictions to be physically deployed in the disaster situations. To enlarge the coverage of LACS-based service, we propose the using of a message ferry (i.e., LACS attached to a drone) or links to form the LACS-based network. As stated in Section 2.3, a standalone LACS is installed to each disaster shelter and local headquarters. In the aftermath of a disaster, the message ferry is deployed from the local headquarters to the disaster shelters to collect and deliver urgent and vital information that is useful in the disaster recovery and management as shown in Figure 6. The LACS attached to the drone acts as an information carrier. Using the storage and Wi-Fi functions of LACS, the message ferry has access to the ground based LACSs via wireless link. After deployment of the message ferry, the message ferry moves around each disaster shelter and collect/deliver information by performing inter-LACS data transfer between the LACS of the message ferry and the pre-deployed LACS (i.e., standalone LACS) at the disaster shelter. In addition, the message ferry utilized the LACS synchronization function to communicate with other LACS in close proximity. In this proposal, the message ferry acts as links in the LACS network, as shown in Figure 7.  
In addition, the LACS's battery can serve as a backup power supply to the message ferry in order to improve one of the constraints (i.e., limited amount of energy) identified in [10] as a hindrance to deploying UAV in a critical situation. This will allow the message ferry to land safely in a situation where the drone energy is depleted. Figure 6: Proposed message ferry using LACS for disaster information collection/delivery. The proposed ferry is more advantageous than the current approach (i.e., using drones as a communication relay) in that more distance can be covered without pre-configuration of the network. In addition, with the proposed approach, the proposed message ferry can be utilized to effectively transfer large amount of data at a high speed compared to other wireless technologies such as Wi-SUN and LoRa as stated in [22; 23; 31; 32]. Wi-SUN has a range of 5 km at up to 250 kbps while LoRa can cover up to 15 km at 50 kbps. In contrast, the proposed message ferry is expected to achieve LACS service coverage of 20 km at 1 Mbps. Therefore, the effective data transmission speed that the message ferry can achieve in such situation is analyzed at various coverage distances in our evaluation. The LACS prototype is attached to a high performance drone (ACSL-PF2 model from Autonomous Control Systems Laboratory) [33] to form the proposed message ferry. Specifically, a PF2-delivery drone that is capable of performing an autonomous flight for safely transportation, logistics and home delivery was used. The drone has the following specifications: total length = 1173 mm, height = 526 mm excluding the antenna, flight speed = 10 m/s (horizontal), 3 m/s (rise), 2 m/s (down), wind speed = 10 m/s, and maximum payload = 2.75 kg.