"Subconscious Mode" Could Boost Phone Battery Life 85
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."
Re:Old ideas live again (Score:4, Interesting)
which is also painfully obvious to anyone in the field. microcontrollers have had multiple clock inputs and internal oscillator blocks with support for switching between them built in for decades. You can also switch the low speed osc off while the high speed one is running if you're obsessive.
Its also painfully obvious to the RF engineering crowd. "obviously" if you have a multiplier chain the high freq mults are going to draw more power than the low freq mults. mults are never known for efficiency so if you have a couple stages you'll find most of your power is dropped in them not the osc. Also you wanna keep the crystal running all the time so its stable, constant temp, etc. Heck keep the first mult stage or so running to keep the load on the osc stable, if you want. That way the calibration output is theoretically usable all the time, instead of being FM modulated as you turn the mults on and off.
Anyway, when you're actively TX or RX, then, and only then, power up the higher freq multipliers in the RX or TX chain (assuming you have 2 separate chains, you just got an instant 50% power savings at the cost of some complicated power wiring). If you're leaving the xtal powered up 24x7 to enhance stability, then powering down the multipliers seems terribly obvious... so that's exactly what they did in ye olden days. When I was a kid I fooled around with some even then obsolete motorola VHF TX and RX strips that had this "obvious" power saving feature.
I don't have a cite, but pick up VHF/UHF/microwave oriented ham radio manuals from about half a century ago, you'll probably be successful.
Merely terminating the last mult stage in a microprocessor clock input instead of a RF mixer is not exactly insightful or patent worthy. Its the equivalent of patenting the concept of using AA batteries in a flashlight instead of their traditional use in kids toys.
The patent is probably much more specific to get around the staggering quantity of prior art. Probably specs the exact layer 2 framing protocol complete with diagrams of the sync header and stuff.