Energy-aware time synchronization in sensor networks: a Two-clock approach

In this paper we consider an energy-constrained synchronized sleep-awake sensor network, where nodes periodically wake up to a scheduled rendezvous. In such a network, the energy needed to keep the clocks ticking in a node´s sleep period can dominate the energy expenditure of a node. Since higher clock accuracy usually implies higher energy cost, we propose a two-clock system. On each node we have a low-quality clock to use when nodes are in sleep mode; and a high-quality clock to use when nodes are active. The low-quality clock is needed for a node to wake itself up. By employing a high-quality clock at each node, the nodes collectively keep an accurate time reference.