A secure data gathering in a Wireless Sensor Network(WSN) has given attention to one of security issues. In general, the process of secure data gathering causes difficulties: one process is exchanging the secured data and the other is constructing secured data path. The previous studies have been resolving the difficulties in terms of two problems: security and data gathering in WSNs. However, a WSN requires a protocol that has to guarantee a security of path between sensors and sink, or a cluster head. Thus how to gather data securely is an important issue. In this paper, we propose a secure data gathering protocol over WSNs, which consists of hierarchical key settlement and secure path construction, and aims at tackling two problems. The proposed protocol causes little overhead to sensor nodes for secured key settlement and path construction. This work provides security analysis focused on the key settlement protocol and evaluates network performance for the proposed data gathering protocol through simulation.

Wi-Fi Direct allows battery powered mobile devices to form a wireless ad hoc network. Since one member of the network called Group Owner (GO) takes the role of managing the network, the network lifetime is mainly affected by the energy efficiency of GO. Hence, Wi-Fi Direct defines power saving schemes that allow GO to save the energy by turning off its radio interface during the periods called absence periods. However, the Wi-Fi Direct specification does not specify how to set parameters (denoted by PS parameters) determining the schedule of the absence periods. In this paper, we therefore propose a novel traffic-aware power saving scheme for Wi-Fi Direct networks. In particular, the proposed scheme estimates the application-level traffic load and adaptively tunes the PS parameters according to the estimated value.