H.323 Annex I Sim Conditions

Adam Li adamli at icsl.ucla.edu
Tue Jan 30 01:04:58 EST 2001


Mr. Baese, experts,

Thank you for your response to our simulation scenario sent on 12/21/2000.
However, it is not clear from your email how you suggest to modify it.

> as you wished we kindly reviewed your paper. Here are our conclusions:
> *	it does not incorporate both the conditions used in your simulation
> 	and the scenario we proposed in APC-1993 correctly
> *	it does not incorporate the decisions of the group at the Geneva
> meeting

Can you be more specific on which testing conditions that we missed, or
which decision of the group at Geneva that I did not incorporate? Please be
a little specific so we can work to make it better.

> To regiment the length of slices is only in favour of the UCLA proposal.
> Therefore
> we don't want to see this restriction within the test scenario.

I think you refer to the following paragraph of the simulation document.

"When the Annex K and/or Annex V is used, the length of the slice should be
such to make packets fit in the length of segment to avoid segmentation of
the IP packet (for fixed segment-loss-rate channels, see below)."

This conditions is NOT in favor of either proposal. It is a fair condition
which is important to evaluate the performance of protection schemes. Let me
explain:

If one want to evaluate if a protection scheme works, s/he need to show how
much the performance improves between the cases "with" and "without" the
proposed scheme. For a realistic measurement of the gain, the benchmark
performance in the "without" case that one compared to needs to be the
(near) optimal scenario. In other word, to demonstrate effectiveness of any
scheme, one need to show that it can provide any gain over the *best* case
the system has without it.

I think Mr. Baese agrees that use the right video slice length to avoid
segmentation gives the (near) optimal performance for the case *without* any
protection. That is the benchmark case that both of our proposals need to be
compared to. This requirement is a fair condition and is not in favor of
either proposal.

We are looking forward to hearing your comments on this and hope we can
reach an agreement on the testing conditions soon.

Adam Li


----------
Adam H. Li
Image Communication Lab                    (310) 825-5178 (Lab)
University of California, Los Angeles      (310) 825-7928 (Fax)





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