Hi Aaron:
Some comments inline..
Aaron Falk wrote:
>
> > If we do not change the wording/content, it is very easy for someone
> > in Wireless to say.."Oh, cdma2000 is not very TCP friendly, Where as
> > UMTS, HDR (1X-EV-DO), GPRS are" --- That is WRONG. All these systems
> > need TCP fixes if the resource allocation is not TCP friendly. The
> > solution to the problem is to fix the allocation scheme and let TCP
> > be transparent. Each Vendor has their own way of fixing this and
> > operator ultimately chooses the one which works the best!
>
> I think the doc should say (based on Farid's work) that this behavior is of
> specific concern to CDMA2000 networks because there is an increased
> liklihood of a MAC configuration which exhibits it. Do you disagree that
> this is the case?
Yes.
>
> > 2. It is not always possible for bandwidth oscillation to exist in
> > CDMA-2000. Hence, the study cases in Farid's ID are kind of "specific
> > examples".
>
> Can you give specific counter examples?
Sorry, I can't do it! (It may sound funny but such information is deemed
proprietary)
>
> > We have worked for the last 3 years on HTTP,FTP/TCP over
> > CDMA-2000 and hence I can tell you that much! If anyone is
> > interested, they can look at our VTC-2000 Spring paper (on just TCP)
> > or MMT-2000 (with HTTP also) one.
>
> URLs would be helpful here.
>
> > These for static rates.
>
> Um, bandwidth oscillation = dynamic rates != static rates, right? Do these
> references address the issue we discussing or are you supporting your claim
> to be knowledgeable in the field?
No, these references do not show counter evidence. It is some proof that
we have worked on TCP over cdma2000!
>
> > If the recommendations are generic for all Wireless Schemes, then they
> > should be included in an RFC. Otherwise, we should hold on or explain
> > the problem and fixes with a "generic" tone..without highlighting
> > cdma2000 alone.
>
> So, as a non-expert in this area I'm still fuzzy about whether
>
> a) there are significant examples of CDMA2000 MACs which do not exhibit
> bandwidth oscillation (i.e., can this be fixed with proper MAC tuning)?
My answer is Yes. Even Farid has commented on this to some extent, I am
pasting his comments from the previous mail...
IS-2000.5 specifies 14 options for finite Duration Supplemental Channel
assignment.
When we evaluated TCP performance for some of those options, we found that
TCP didn't like them.
It is true that vendors and/or operators may choose different
configurations.
However, it is important to realize that choosing a "better" SCH duration
may come at the
cost of additional signaling in the network which has implications to
interference limited capacity.
If you consider scheduling of users (especially with different QoS classes)
, the problem becomes
more complex. Even in "properly" designed sub-networks, admitting more users
means
more revenue, but also increases likelihood of bandwidth oscillation.
>
> b) the type of bandwidth oscillation which affects TCP performance is also
> present in other 2.5g/3g systems.
>
> I'd like to hear some more voices here.
I would like to also!
Thanks,
Kamesh
This archive was generated by hypermail 2b29 : Mon Jan 28 2002 - 09:12:29 EST