Hi,

Can someone check if these values are correct estimations.
InitialBackoff

InitialBackoff=( call Random.rand16()  % (0x1F * CC2420_BACKOFF_PERIOD) + 
CC2420_MIN_BACKOFF);

Min value Initial Backoff
InitialBackoff = [ (0) % (31 * (20/2)) + 20/2] = 10

Max value Initial Backoff
InitialBackoff = [ (65535) % (31 * 20/2)+ 20/2] = [309+10] =319

Time in milliseconds =
Min Time = 10/2*0.0305= 0.1525 milliseconds
Max Tim = 319/2*0.0305= 4.8647 milliseconds
1 jiffies=0.0305ms

CongestionBackoff

CongestionBackoff =
( call Random.rand16()  %  (0x7 * 
CC2420_BACKOFF_PERIOD)+CC2420_MIN_BACKOFF);

Min value Congestion Backoff
CongestionBackoff = [ (0) % (7 * (20/2)) + 20/2] = 10

Max value Congestion Backoff
CongestionBackoff = [ (65535) % (7 * 20/2)+ 20/2] = [69+10] =79

Time in milliseconds =
Min Time = 10/2*0.0305= 0.1525 milliseconds
Max Tim = 79/2*0.0305= 1.20475 milliseconds
1 jiffies=0.0305ms

Regards,

Tipu Sultan

Masters Student in Network, Services and Systems.
KTH - Royal Institute of Technology, Stockholm, Sweden


> Hi,
>
> I am new to TinyOS and I am trying to change the values for CCA backoff 
> timers. From tep126, I have learned that I can change InitialBackoff and 
> CongestionBackoff. Then looking in CC2420CsmaP.nc and RadioBackoff.nc what 
> I have understood is that values should be changed through 
> requestInitialBackoff event. My question is that what command returns 
> these events, like SplitControl.start() returns the event 
> SplitControl.startDone(error_t error).
>
> Secondly I would like to ask that calling setInitialBackoff(backoffTime); 
> will change the value, but backoffTime is unspecified unit how to 
> calculate it in term of milli seconds or any know term and what is the 
> default value for backoffTime in initialBackoff and congenstionBackoff.
>
> Lastly if you can guide me to a sample program where Backoff timer changes 
> are implemented it will be really nice.
>
> I would really appreciate your help.
>
>
> Regards,
>
> Tipu Sultan
>
> Masters Student in Network, Services and Systems.
>
> KTH - Royal Institute of Technology, Stockholm, Sweden
 

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