Energy-efficient adaptive interface activation for delay/disruption tolerant networks

In sparse mobile networks, opportunistic access can be used to forward data in a so-called "store-carry-forward" manner using DelaylDisruption Tolerant Networking (DTN) techniques. In such environments, it is not always the case that a mobile terminal is within the communication range of other mobile terminals. Therefore, the terminal must first perform the energy-consuming process of "terminal discovery" before sending or receiving actual data. Since a mobile terminal is normally battery powered, it is a mandatory requirement to cut power consumption. Therefore, the discovery process must be executed efficiently. In other words, it is imperative to activate a network interface at the right time. In this paper, we analyze the performance issues with simple periodical interface activation and propose a new activation mechanism called DWARF (DTN-oriented wireless interface activation mechanism based on radio fluctuations) for efficiently discovering other terminals with less expenditure of energy. In the proposed mechanism, the interface activation interval is adjusted based on the surroundings. DWARF is a distributed mechanism and does not require prior knowledge such as patterns of human behavior. Computer simulation results show that DWARF discovers other terminals about 3.5 times more efficiently than a fixed-interval scheme without missing opportunities for connection.