[e2e] How measered Jitter is incorporated in E-Model

[Christian Hoene]

Dear Amir Mehmood,

It is best is to measure the distribution of delay values. Jitter - or 
more precise delay variance - is not important. Only the distribution is 
relevant. The packet trace would be even better.

The overall delay (including playout buffering and the transmission) and 
the overall loss rate (including late and lost packets) can be used in 
the ITU E-Model to calculate the conversational quality (measured with 
the R factor).

If you then assume fixed playout buffer lengths (e.g. from 20 to 200ms), 
you can calculate the overall delay and the losses due to late packets. 
The delay distribution can be map to loss and delay values, which can be 
used to calculate an optimal R factor or MOS quality rating. 

However, this approach is problematic because to try to find an optimal 
fixed playout buffer length AFTER the transmission. An real-time 
adaptive playout scheduling would be more realistic.

In the publication [1] we addressed this issue and provide an 
open-source software to assess the transmission VoIP with a precision 
that has not been reached before. But you can use (and adapt) the 
software (which is somewhat complicated to install, sorry) to solve your 
task.

Good luck,

    Christian Hoene
    TKN TU-Berlin

[1]C. Hoene, S. Wiethölter, and A. Wolisz 
<mailto:hoene at tkn.tu-berlin.de>, "Predicting the Perceptual Service 
Quality Using a Trace of VoIP Packets", In /Proc. of Fifth International 
Workshop on Quality of future Internet Services (QofIS'04)/, Barcelona, 
Spain, September 2004.
(PDF <http://www.tkn.tu-berlin.de/publications/papers/hoene2004qofis.pdf>)


> Subject: 	[e2e] How measered Jitter is incorporated in E-Model
> Date: 	Fri, 3 Jun 2005 11:33:39 +0500
> From: 	Aamir Mehmood <am.amir at gmail.com>
> Reply-To: 	Aamir Mehmood <am.amir at gmail.com>
> To: 	end2end-interest at postel.org
>
>
>Hi
>
>We are doing performance analysis of our country's internet exchange.
>We have measured jitter for voice calls on the backbone links.
>
>Can some one please let me know that how can i incorporate that
>measured value into the E- Model ( ITU G.107)
>
>Regards
>
>
>Amir
>  
>