Sleep-aware mode assignment in wireless embedded systems

Minimizing energy consumption is a key issue in designing wireless embedded systems. While a lot of work has been done to manage energy consumption on single processor real-time systems, little work has been done in network-wide energy consumption management for real-time tasks. Existing work on network-wide energy minimization assumes that the underlying network is always connected, which is not consistent with the practice in which wireless nodes often turn off their network interfaces in a sleep schedule to reduce energy consumption. Moreover, existing sleep scheduling techniques are unaware of computation status and often lead to unnecessary wakeup overheads. In this paper, we propose solutions to minimize network-wide energy consumption for real-time tasks with precedence constraints executing on wireless embedded systems. Our solutions jointly consider the radio sleep scheduling of wireless nodes and the execution modes of processors. Based on different wireless network topologies, we propose energy management schemes to minimize energy consumption while guaranteeing the timing constraint and precedence constraint. When the precedence graph is a tree, our solution gives optimal result on energy management. The experiments show that our approach significantly reduces total energy consumption compared with previous works.