Farid, Andrei:
If the experiments are applicable to various technologies, my suggestion at
this point is to create a subsection in either the 2.5g3g ID and/or LINK ID.
It should first unambiguosly state that the problem is quite general and it
exists in both wireless and wireline systems. Then as a specific example,
describe why it is possible in GPRS, UMTS and CDMA-2000 2.5g3g Technologies.
After the description, mention the experiments, results and recommendations
(if any). Be sure that the results and recommendations apply across
technologies. If they do not, there should be no additions made either
of the drafts based on your material - at this time. If you do not have
sufficient evidence to prove the general applicability of the solutions,
we should wait for the study to be completed. Good results should always
be published and I appreciate your willingness to do that.
Recommendations should be general. Otherwise, it doesn't make sense to
highlight the issue by considering "one of the possible systems" and then
proposing the solution for "that particular system". This issue gets a lot
more tricky when you start dealing with 3G technologies. I believe you
agree with those thoughts.
Thanks,
Kamesh
Farid Khafizov wrote:
>
> Part 1.1Type: Plain Text (text/plain)
Dear all:
We would like to clarify a few things about our previous correspondence.
We believe this forum is not a place for deciding which 3G wireless
technology
is better and this definitely was not our intention. This forum should be
objective and not biased
towards any technology. We have no reason to think that CDMA2000 is inferior
to UMTS.
If the proposed text implies that, as some have suggested, we must make
necessary changes to the text.
Furthermore, it was not our intention to say or imply that Bandwidth
Oscillation
is *characteristic* of any particular network. This should be emphasized in
the text.
In the proposed text referring to UMTS and/or CDMA2000 we never say *will*.
Specifically discussing bandwidth oscillation, we say "may" or "can".
Like in UMTS, there are various ways to avoid bandwidth oscillation in
CDMA2000.
That is why it was decided to address this issue in LINK ID.
We used CDMA2000 only as an example. UMTS could have been picked as an
example too,
if someone does "periodic switch between a high speed dedicated and the
common channels. "
2.5g/3g ID is addressing issues of the networks that have not been widely
deployed.
Initial field reports from operators do not look very rosy. Doing a search
on the web would show
that expectations for 3g wireless data speed are much lower than originally
thought.
At this point it is reasonable to say that we do not know *all* TCP issues
related to 3g wireless.
Only time will show what they are and how to address them. In the absence of
data from
live networks with multiple users, one has to make certain assumptions on
how those network
might operate and draw conclusions based on those assumptions.
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. So, an
operator might still be interested in choosing non-optimal configuration
options (allowed by the standards)
as long as he can reduce throughput degradation by optimizing TCP.
That is the main reason why we think bandwidth oscillation should be
addressed in 2.5g/3g ID.
At this point, we can either remove the Bandwidth Oscillation text from the
draft and
pretend that it may never happen , or we can specifically state that
Bandwidth Oscillation is a potential problems which MIGHT show up and
offer TCP optimization techniques.
--Farid
> -----Original Message-----
> From: Andrei Gurtov [SMTP:gurtov@cs.Helsinki.FI]
> Sent: Friday, January 25, 2002 12:42 AM
> To: Kamesh Medepalli; Behcet Sarikaya
> Cc: pilc@grc.nasa.gov; francois.courau@alcatel.fr
> Subject: Re: Re:2.5g/3g ID additions (RE: pilc minutes (corrected))
>
> I agree that the problem of 'bandwidth oscillation' itself is not new.
> While
> not saying anything on cdma2000 vs. umts, I think we should not be so
> negative about this draft. The authors have done a very good job for
> example
> by experimenting on how existing different TCP implementations react to
> this
> type of RTT changes, evaluating the effect of different TCP features like
> timestamps or restarting the retransmit timer on ACKs.
>
> After all, the final product is as good as its implementations and there
> was
> certainly something to learn for vendors and operators from this draft.
> Again, not saying that this is a good way to do the resource allocation...
>
> Andrei/
> Sonera
>
> ----- Original Message -----
> From: "Kamesh Medepalli" <medepalli@lucent.com>
> To: "Behcet Sarikaya" <sarikayab@yahoo.com>
> Cc: <pilc@grc.nasa.gov>; <francois.courau@alcatel.fr>
> Sent: Thursday, January 24, 2002 6:19 PM
> Subject: Re:2.5g/3g ID additions (RE: pilc minutes (corrected))
>
>
> > I am not sure why the CDMA2000 ID was even considered seriously. It is
> > standard problem that needs to be addressed carefully at the MAC layer.
> > I am surprised folks actually went up to writing something like this
> > and blaming it on CDMA2000 in a way! Standards define the basic MAC
> > protocol. It is upto the Vendors to design "algorithms" for resource
> > allocation.
> >
> > What happened to Phil Karn's and Gorry's comments which were raised very
> > early after the initial draft was sent out?
> >
> > Clearly it is not a CDMA2000 vs UMTS argument etc. It is easy for such
> > problems to arise if someone used Downlink Shared Channel (DSCH) in UMTS
> > in a random manner..ofcourse dedicated channels (DCH) help.
> >
> > I hope others in the mailing list raise their voice too!
> >
> > Thanks Behcet!
> > Kamesh
> >
> > Behcet Sarikaya wrote:
> > >
> > > Dear all,
> > > I am forwarding the opinion of Francois Courau from
> > > Alcatel France (who is the head of 3GPP RAN WG) on
> > > this issue.
> > > I wish we could get another expert opinion of
> > > someone from Lucent or Qualcomm on the situation in
> > > CDMA2000. I am afraid if we include Farid's text only
> > > for CDMA2000 this will cause problems as to the
> > > inferiority of CDMA2000 vis-a-vis UMTS.
> > >
> > > Regards,
> > >
> > > --behcet
> > >
> > > --- Francois.Courau@alcatel.fr wrote:
> > > > Subject: Re: Fwd: Re: 2.5g/3g ID additions (RE: pilc
> > > > minutes (corrected))
> > > > To: Behcet Sarikaya <sarikayab@yahoo.com>
> > > > From: Francois.Courau@alcatel.fr
> > > > Date: Thu, 24 Jan 2002 11:18:44 +0100
> > > >
> > > >
> > > > I fully share the analysis proposed by Ericsson. The
> > > > oscillation will be
> > > > linked with the reduction of throughpur decided
> > > > uponn by the radio access
> > > > network in the other cases we don't have a similar
> > > > problem to CDMA 2000.
> > > >
> > > > Francois
> > > >
> > >
> > > __________________________________________________
> > > Do You Yahoo!?
> > > Great stuff seeking new owners in Yahoo! Auctions!
> > > http://auctions.yahoo.com
> >
>
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