[Tinyos-devel] DutyCycle vs SleepInterval

[Omprakash Gnawali]

I vote for sleep interval.

- om_p

On Sun, Jan 11, 2009 at 7:20 AM, Miklos Maroti <mmaroti at math.u-szeged.hu> wrote:
> Hi!
>
> I vote for sleep interval (less portable, but much more predictable)
>
> Miklos
>
> On Sat, Jan 10, 2009 at 2:56 AM, Razvan Musaloiu-E. <razvanm at cs.jhu.edu> wrote:
>> Hi!
>>
>> The current LowPowerListening [1] interface contains two sets of
>> commands: one using intervals expressing sleep intervals and another one
>> using percentages expressing duty-cycles. What I would like to bring into
>> discussion is the duty-cycles.
>>
>> For reference here is the interface:
>>
>>        interface LowPowerListening {
>>          command void setLocalSleepInterval(uint16_t sleepIntervalMs);
>>          command uint16_t getLocalSleepInterval();
>>          command void setRxSleepInterval(message_t *msg, uint16_t sleepIntervalMs);
>>          command uint16_t getRxSleepInterval(message_t *msg);
>>
>>          command void setLocalDutyCycle(uint16_t dutyCycle);
>>          command uint16_t getLocalDutyCycle();
>>          command void setRxDutyCycle(message_t *msg, uint16_t dutyCycle);
>>          command uint16_t getRxDutyCycle(message_t *msg);
>>
>>          command uint16_t dutyCycleToSleepInterval(uint16_t dutyCycle);
>>          command uint16_t sleepIntervalToDutyCycle(uint16_t sleepInterval);
>>        }
>>
>>
>> So for intervals we have 64K possible values. The duty cycles are
>> expressed in 1/100 increments so for them we have 10000 possible values.
>> For CC2420 these 10000 values actually corresponds only to about 650
>> unique sleep intervals.
>>
>> Another issue is the fact that the duty-cycle is not guarantee. The
>> current LPL doesn't track the achieved duty-cycle and dynamically adjust
>> the sleep intervals in order to meet a certain one. What happens is a
>> fixed sleep interval is picked by translating the duty-cycle to a sleep
>> interval using a fixed knowledge about how much the probing should take.
>> So basically the semantics is that that duty-cycle will be achieved only
>> if there is no traffic and no false wakeups. I find this definition
>> cumbersome and not very attractive to work with.
>>
>> So my questions are: what do people think about this? Do you usually use
>> intervals or duty-cycles in your LPL applications? How does sliming down
>> the LowPowerInterface to only 4 calls sound? :-)
>>
>> [1] http://tinyos.cvs.sourceforge.net/*checkout*/tinyos/tinyos-2.x/doc/html/tep105.html
>>
>> All the best!
>> Razvan ME
>> _______________________________________________
>> Tinyos-devel mailing list
>> Tinyos-devel at millennium.berkeley.edu
>> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-devel
>>
> _______________________________________________
> Tinyos-devel mailing list
> Tinyos-devel at millennium.berkeley.edu
> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-devel
>