Energy Management on Handheld Devices

Abstract

Handheld devices are becoming ubiquitous and as their capabilities increase, they are starting to displace laptop computers - much as laptop computers have displaced desktop computers in many roles. Handheld devices are evolving from today’s PDAs, organizers, cellular phones, and game machines into a variety of new forms. Although partially offset by improvements in low-power electronics, this increased functionality carries a corresponding increase in energy consumption. Second, as a consequence of displacing other pieces of equipment, handheld devices are seeing more use between battery charges. Finally, battery technology is not improving at the same pace as the energy requirements of handheld electronics. Therefore, energy management, once in the realm of desired features, has become an important design requirement and one of the greatest challenges in portable computing, and it will remain so for a long time to come.

Organizing XML Data in a Wireless Broadcast System by Exploiting Structural Similarity

“…In the active mode, a device can listen, compare, and download the required data; while in the doze mode, it turns off antennas and some processes to save energy. The energy consumed in active mode can be up to 100 times of that in doze mode [28]. However, after a broadcast program r is generated, mobile clients cannot locate information of their interests as there is no auxiliary information to assist them, which means mobile clients would need to stay in active mode all the time.…”

Intelligent Data Receiver Mechanism for Wireless Broadcasting System

“…In 1997, Swarup Acharya et al [18] proposed a backchannel to balance the usage between push channels and pull channels. Quinglong Hu et al [13], on the other hand, combined cache and pull-based point-to-point data transmission to realize reduction of access time .…”

“…This type of approach uses index techniques in broadcast program to allow mobile users to read and access data with lower power consumption by reducing tuning time [13] spent on reading data at the mobile client's side. This type of research focuses on allowing a mobile device to switch to doze mode when the data being broadcast is not what the user is interested in and switch to active mode when the interesting data is on the air.…”

“…(2) Tuning time does not reflect the real power consumption. Although active mode consumes much more power than doze mode, approximately 20 times more [13], saving tuning time at the cost of waiting time shall not make for the least total power consumption. (3) The environments in which the two types of researches are applied are different.…”

“…Generally speaking, in order to save power, typical mobile devices support two operation modes: active mode and doze mode. A typical wireless PC card consumes 60mW in doze mode and 805-1400mW in active mode [13].…”