back to article Boffins crack smartphone Wi-Fi for greater battery life

Researchers have worked out another method for dramatically boosting a smartphone's battery life, by devising a new "subconscious" mode of operation. A couple of boffins from the University of Michigan have created a conceptual system called E-MILi, or Energy-Minimalising Idle Listening, that looks at the energy wasted when …

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??

Their power figures for the stations are way off. RX is definitely much lower than TX. The largest power consumer is the power amp not the ADC.

I think this is a desktop card they have analysed, and these are non optimised for power consumption.

Also this seems to be only for directed packets, and "idle listening" is mostly with non directed packets. Carrier sense is only required before a TX when medium contention occurs. Here also RX can be killed after preamble detection.

So while there is an advantage, the benefit don't seem to be worth the effort, especially as the device is not 802.11 PHY compliant anymore. It can work with older stations, but this is not guaranteed. Those M-preambles before the frame violate the timing.

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Or ...

Switch it off when not in use?

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other technologies build this in from the start

Digital cellular technologies like GSM and CDMA all knew about this user device battery drain problem when they were designing the network standards. In CDMA it is called "slotted mode", where the network and handset agree how often to send out notifications. By doing that at prearranged times it allows the handset/chipset to drop into deep sleep for a second or so, and only wake up for milliseconds at a time to listen for its name to be called. Tremendous savings in battery power.

It seems that Wi-Fi didn't built it in, so these guys had to find a way to duct-tape one into it?

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Silver badge

Anything that helps practically extend battery life works for me.

Well done lads.

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Look ... it's here ...

http://www.theregister.co.uk/2011/09/16/boffins_boost_battery_life_underclocking_wifi/

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