Energy-efficient carpool policy for wireless interfaces of mobile devices in ubiquitous environments

Nowadays, power consumption is a big concern for mobile devices because battery power of mobile devices is one of the most crucial resources. Unfortunately, the performance of battery power fails to meet the power needs of high-end mobile devices. Increased data to be transferred/received through wireless communication incur high power consumption, because the wireless communication interface is one of the most dominant modules of mobile devices in terms of power consumption. Therefore, efficient power management of wireless interfaces should be employed for mobile devices. Dynamic power management is widely employed in order to support multiple power modes such as active modes (e.g., transmit, receive, and idle mode) and inactive modes (e.g., sleep mode and power off). Therefore maximizing the staying time of the wireless interface in an inactive mode is an essential scheme to reduce energy expenditure. However, required overhead energy and time for turning on/off the wireless interface are not negligible. Most of recent works have been trying to enhance the hardware architecture or network/MAC protocols. In this paper, we present an energy-efficient carpool policy that turns on the wireless interface and transmits all awaited data only when the predefined threshold is exceeded. We propose two kinds of thresholds–time and space. For practical evaluation, we conduct not only simulations but also experimental measurements by implementing a test program on a real test bed. Results of simulation and experimental measurements show that our proposed scheme incurs less energy expenditure than legacy power management schemes do.