Battery-saving message collection method for disrupted communication service areas

The paper proposes a collection method of SOS messages in a disaster area with collapsed communication service. So far, we have proposed and implemented SOSCast as a smartphone application to support rescue operations for finding immobilized victims. However, in its current implementation, we found that SOSCast limits the search coverage area and disregards some SOS messages. Moreover, the smartphone rapidly consumes battery due to the required constant communication. We propose, therefore, to implement Wi-Fi Direct (WD) in addition to Bluetooth (BT) to increase the search coverage area. Furthermore, we introduce an information-sharing cluster in order to collect SOS messages efficiently while preserving the smartphones' battery life. By implementing the proposed methods on actual smartphones for a performance evaluation, we showed that controlling the use of both WD and BT increases the probability of locating immobilized victims. Also, enabling an information-sharing cluster by immobilized victims' smartphones can send SOS messages to a mobile victim smartphone all at once, which can extend the lifetime of the smartphone's battery as compared with the previous method.