Mobile Sensor Node Deployment Strategy by using Graph Structure based on Estimation of Communication Connectivity and Movement Path
International Journal of Advanced Computer Science and Applications
We propose a multiple-mobile sensor node (MSN) deployment strategy that considers wireless communication quality and operation time of underground wireless sensor networks. After an underground disaster, it is difficult to perform a rescue operation because the internal situation cannot be confirmed. Hence, gathering information using a teleoperated robot has been widely discussed. However, wireless communication is unstable and the corresponding wireless infrastructure to operate the
... erate the teleoperated robot is unavailable underground. Therefore, we studied the disaster informationgathering support system using wireless sensor networks and a rescue robot. In this study, the movement path information of the teleoperated robot is fed to MSNs in a graph structure. MSNs are deployed in the underground environment by adding an evaluation of communication quality and operation status to a given graph structure. The simulation was evaluated in an assumed underground environment. The results confirmed that the wireless communication quality between each MSN was maintained and energy consumption was balanced during the deployment. Keywords-Wireless sensor networks; deployment strategy; communication connectivity From studies based on past accident analysis, researchers have recently focused on a disaster information-gathering method using a wireless sensor network (WSN) and a rescue robot in closed areas. The WSN consists of spatially distributed sensor nodes (SNs) to cooperatively monitor environmental conditions such as temperature, sound, vibration, pressure, motion, etc. The WSN is then enabled to provide wireless communication without the existing infrastructure. In a closed area, it is constructed using a rescue robot. Therefore, an information-gathering method by constructing the communication infrastructure in a disaster area using a WSN has been discussed [6, 7] . However, the scope of application is limited to outside the disaster area, and studies assuming a closed space have not been reported. Information gathering by rescue robots and disaster rescue support systems is effective. The use of robot technology can reduce the activity burden on rescue workers. Rescue robots are often remotely controlled by considering the impact on the disaster area and work safety. When the robot is operated remotely, it is possible to support rescue operations in spaces where people cannot easily enter, such as closed spaces, narrow spaces, and underwater. The connectivity and stability of communication are very important during remotely controlled operations. Owing to the closed environment, wireless communication is often unstable underground, as compared to the outdoors. Hence, degradation of wireless communication due to disturbances such as fading and shadowing is more likely to occur underground than outdoors. Therefore, we studied the information-gathering system using teleoperated robots and WSNs, as observed in Fig. 1 [8 -10]. In this system, a WSN is constructed using a mobile sensor node (MSN). This system responds quickly to network disconnection. This system reports that the end-to-end throughput was maintained and an effective WSN was constructed. However, the autonomous deployment of each MSN is unavailable in this system. In environments where wireless communication is unstable, such as the underground, the MSN must be placed in a position that provides a stable wireless relay to maintain the communication connection for the teleoperated robot. In addition, the MSN has limited energy because the power supply is a battery. Hence, it is important for the WSN that there is no network disconnection when the MSN stops operating.