Energy Management Mechanisms for Wireless Real-time Environments

Efficient energy management is extremely critical to the operation and performance of mobile and wireless systems as a result of the limited energy resources (e.g., battery charge) available to these devices. This work observes existing energy management techniques in distributed wireless environments to be non-cooperative in the sense that they reduce the energy consumption of a single device, disregarding potential consequences for other constraints (e.g., end-to-end deadlines) and/or other devices (e.g., energy consumption of neighboring devices). It is shown that energy management in such environments has to be end-to-end in nature, requiring a coordinated approach among participating devices. In this regard, two novel mechanisms, Cooperative Dynamic Voltage Scaling (Co-DVS) and Adaptive Fragmentation are proposed. The Co-DVS mechanism coordinates the individual DVS components at each node such that i) end-to-end latencies are maintained within specified timeliness requirements (deadlines) and ii) higher energy savings are achieved at nodes with the highest pay-off factors that represent the relative benefits of conserving energy at a node. Similarly, the Adaptive Fragmentation mechanism chooses an optimal link-layer fragment size that i) satisfies end-to-end delay requirements and ii) minimizes the energy consumption of the source device by lowering the re-transmission costs.