Dear authors, I have recently read the ippm-delay-var-as draft and believe it is on the right way. For me it is clearly the most complete comparison PDV vs. IPDV up to now and very helpful to understand the nitpicks of each definition. Let me add a few observations from my own work in this area here: a) as PDV is clearly a shifted version of the delay itself, its statistics can be directly derived from the delay (OWD) statistics when in addition the reference value is known. Even though I believe it has its own justification and use. b) For IPDV it would be nice to know, how symmetrical it is in practice. If it is very symmetric in almost all cases then one might as well work with the stats applied to abs(IPDV) only. If unsymmetric IPDV distributions appear then one should present a positive and a negative high percentile or something like inter-quartile range as resulting statistics (in addition to mean IPDV in any case) Does anyone have results wrt. the symmetricity? c) Esp. for IPDV it is not clear to me the effect of the packet selection function: Esp. the question: Does the size of the gaps between selected packets have an influence on the distribution of the resulting IPDV values? (in theory yes (I could give an example), but in practice?) I will have a more detailed look at the draft in the next week and then write some specific comments as well. In general I'd say the draft should be concluded with something like a table which recomends clearly the use of PDV or IPDV and suggested stats per desired application. Best regards, Carsten. -- ### !! ATTENTION !! Change of email address! Please use in future only: carsten.schmoll at fokus.fraunhofer.de ### "The difference between theory and practice is that in theory theory and practice are the same but in practice they are not." Dipl.Ing. Carsten Schmoll Fraunhofer Institute FOKUS carsten.schmoll at fokus.fraunhofer.de National Research Institute Fraunhofer FOKUS / dept. NET for Open Communication Systems Tel: +49-30-3463-7136 Kaiserin-Augusta-Allee 31 Fax: +49-30-3463-8136 D-10589 Berlin, Germany
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