Subject: [rmcat] Comments on NADA algorithm update and test case evaluations

From: Ingemar Johansson S <[email-masked]>
Date: Sun, 9 Nov 2014 20:03:45 +0000

Hi

Thanks for the illustrative slide set, it helped me to understand the concept.

A few email questions on your presentation

+Non-linear warping of delay:
I read one of the background papers behind this some time ago, one thing that crossed my mind is that there is a risk that one accidentially may run into the loss/marking based region in cases where several users share a common transmission medium, which is the case e.g with LTE and WiFi access. To take the LTE example with default bearers which is the part I know the best. In cases where new users enter a cell (either because of handover or just because the flows are just started).  New users typically get a higher scheduling weight in cases where proportional fair schedulers are used. This gives already existing users a lower throughput which will manifest itself as a temporary larger delay.
The outcome may then be that the loss/marking region is enterered even though there is in actually no competing flow on the bearer, rather it is a case of competing bearers.
Once there it can be difficult to get back to the delay based region. I have not been able to try out how serious this potential may be.

+Evaluation:
 + Is this evaluation run  with some additional network jitter ?, reason why I ask is that cellular access may add some extra jitter mainly due to scheduling.
 + I see that the graphs indicate the send rate. i.e the output rate from the rate shaping buffer. What about the delay figures, do they depict the network delay (socket to socket) or is it the video frame delay ?

Regards
/Ingemar
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Ingemar Johansson  M.Sc.
Senior Researcher

Ericsson AB
Wireless Access Networks
Labratoriegränd 11
971 28, Luleå, Sweden
Phone +46-1071 43042
SMS/MMS +46-73 078 3289
[email-masked]<mailto:[email-masked]>
www.ericsson.com

"The difference between stupidity and
genius is that genius has its limits."
Albert Einstein
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