alpha  [0, 1] controls the history of the estimator, it is used in function
void updateEst(TableEntry *Nbr)
if u see line 305 in file MultihopWMEWMA.nc
 
tmp = ((2 * ((uint16_t)Nbr->receiveEst) + (uint16_t)newAve * 6) / 8);
 
the 6/8 = (0.75) and 2/8 (0.25) is the Alpha. ie here they use 25% of old value and 75% of new value.
 
 
Rahul Sawant
 
 


On 3/27/06, Vinayak Naik <[EMAIL PROTECTED]> wrote:
I do not know the implementation details of WMEWMA in the MinRoute code under TinyOS.
 
Here are the steps to learn about WMEWMA as a mathematical function:
+ Google Moving Average
+ Google Exponentially Weighted Moving Average
+ I would say that WMEWAMA is EWMA of Mean over a Window. In MintRoute, reliability of a link is calculated over window of period T and EWMA of that windowed mean is calculated to estimate link quality.
 
Alpha is a parameter for EWMA function. It represents the amount of history used to calculate next average.
 
- Vinayak

 
On 3/27/06, Nue Noi < [EMAIL PROTECTED]> wrote:
Hi,

I have a question about MintRoute protocol.
I have read the paper from A.Woo. I couldn't find a similar formular
described in the paper, especially the factor alpha. I went through
the codes in /tos/lib/MintRoute many times but I couldn't find
where this alpha is used. I am doubtful that the alpha value 0.6
in the paper was really implemented in nesC.
I guess that the function used to estimate the link quality is
evaluateCost(). If anybody could explain more in details how
WMEWMA estimator performs following the paper, I would be
very appreciated. Thank you.

Regards,
NueNoi
 

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