"Subconscious Mode" Could Boost Phone Battery Life

cylonlover writes "University of Michigan researchers have proposed a new power management system for smartphones that could dramatically improve battery life. The system, known as E-MiLi, or Energy-Minimizing Idle Listening, addresses the energy waste that occurs when 'sleeping' phones are looking for incoming messages and clear communication channels. E-MiLi slows down the clock of a phone's WiFi card by up to 1/16 its normal frequency in order to save power, but then kicks it back up to full speed when information is coming in. The phone uses the header of the incoming message to wake itself up from its 'subconscious mode,' so the clock is at full speed to receive the main message. For users on the busiest networks, it could extend battery life by up to 54 percent."

Comments

fractions

[Anonymous Coward]

by 1/16th? or up to 1/16th of? - - quite a difference there!

Old ideas live again

[dtmos]

Patent 4,893,271, issued in 1990 and expired, covers an implementation of this idea in which the slow clock is a crystal oscillator, and the high-speed clock is synthesized, using the crystal oscillator as the reference of a phase-locked loop. It was used in tens of millions of Motorola radio pagers for exactly the reason stated in the article -- lower power consumption in sleep mode, while retaining the ability to process fast once a signal appears.

Re:Old ideas live again

[dtmos]

Yes -- the trick is doing it without keeping the high-speed oscillator running all the time. In these kinds of embedded applications, the oscillator can draw a significant amount of power. Implementations that have a high speed oscillator running all the time, but divide it down while in sleep mode, draw more power than the invention, which has a low speed oscillator running all the time, and only generates high frequencies when they are needed.