High-resolution, low-power time synchronization an oxymoron no more

13 years 11 months ago

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We present Virtual High-resolution Time (VHT), a powerproportional time-keeping service that oﬀers a baseline power draw of a low-speed clock (e.g. 32 kHz crystal), but provides the time resolution that only a higher frequency clock could oﬀer (e.g. 8 MHz crystal), and scales essentially linearly with access (i.e. the “reading” and “writing” of the clock). We achieve this performance by revisiting a basic assumption in the design of time-keeping systems – that to achieve a given time-stamping resolution, a free-running timebase of equivalent frequency is needed. We show that this assumption is false and argue that the dependence is not on usage (i.e. whether on or oﬀ) but rather on access (i.e. reading and writing). Therefore, it is possible to duty cycle the free-running timebase itself, and augment it with a lower-frequency, temperature-compensated one, which achieves comparable resolution, at a fraction of the power, for typical workloads. The key technical challeng...

Thomas Schmid, Prabal Dutta, Mani B. Srivastava

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