Joint Sleep Scheduling and Mode Assignment in Wireless Cyber-Physical Systems

Recent years have witnessed the deployment of wireless Cyber-Physical Systems(CPS) for a variety of important applications. A key requirement for wireless CPS systems is to sustain a long lifetime on limited power supplies. At the same time, due to the criticality of CPS applications, many computation and communication tasks must be finished within timing constraints to avoid undesirable or even catastrophic consequences. 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 applications. 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. This paper jointly considers the radio sleep scheduling of wireless nodes and the execution modes of processors. Based on wireless network topologies, different schemes are proposed to minimize energy consumption while guaranteeing the timing and precedence constraints. When the precedence graph is a tree, optimal result on energy management is achieved. The experiments show that our approach significantly reduces total energy consumption compared with the previous work.