Re: [Mipshop] Re: Architectural Considerations for Handover InformationServices (was: Re: CARD Discussion Query Discussion)
Yoshihiro Ohba wrote:
> Qiaobing,
>
> Could you elaborate on the "major portion"? Do you mean the major portion
> is 5 to 9 sec, or the major portion is a part of 5 to 9 sec?
A "major portion" of the overall 5 to 9 sec, but there is no general way
to precisely measure it (see below).
> Also, which is more dominant delay factor in SIP/XML signaling,
> transferring text over the air (transmission delay) or processing text
> on cellular phones (processing delay)?
Both are major - which one is more dominant depends on the particular
design and platform. Transferring text SIP over the air for call control
is unacceptable, this is why both 3GPP and 3GPP2 are critically counting
on rohc/sigcomp from IETF to compress the SIP messages before it goes
over the air. It is a *big* effort for several years (a look in
rohc/sigcomp can tell). The sigcomp compressor/decompressor is
complicated and CPU intensive and is dictionary based. The achievable
compression ratio for SIP still leaves a lot to be desired, and I don't
know whether it can do anything good for embedded XML documents. At the
same time, the processing delay due to the compression/decompression
algorithm is a common issue for most small device design due to their
limited computing power. This hasn't take into account the processing
time for XML handling itself.
> In terms of the sensitivity of IS, as long as IS can be executed
> between handovers and in the middle of the call and in the background
> without disrupting the call, the delay requirement of IS is not
> necessarily much more sensitive than the call setup time, in my
> opinion.
Unfortunately, most handoffs are not predictable, i.e., they depends on
how a UE moves, for example, when a UE moves into a new unfamiliar
network and urgently wants to make a h/o decision, the IS becomes the
most needed! If IS can only satisfy the UE during time insensitive
periods, its usefulness will be severely limited, IMO.
regards,
-Qiaobing
>
> Yoshihiro Ohba
>
>
> On Wed, Oct 19, 2005 at 09:42:08AM -0500, Qiaobing Xie wrote:
> > Michael,
> >
> > I know there are places where xml is involved in call control, e.g., an
> > optional xml document can be embedded in a SIP invite message in some
> > PoC VoIP call control messages in OMA. However, all
> > implementations/empirical data that I am aware of points to that as the
> > cause of a major portion of the call setup delay of PoC (~5-9 sec as
> > reported). It is widely recognized that is a penalty we all are paying
> > for the extensibility, flexibility, and text-based nature of SIP/XML
> > call control signaling and tremendous effort and resources have been
> > spent to reduce the VoIP call setup latency across the industry.
> > Fortunately, that only happens once at the setup of a call (I am not
> > aware of any significant SIP/XML signaling used mid-session).
> >
> > In my view, handoff is much more time sensitive than the call setup from
> > a user's perspective and handoff can happen repeatedly in a call. Making
> > XML handling part of the handoff procedure may not be a good idea at
> all.
> >
> > regards,
> > -Qiaobing
> >
> > Michael.G.Williams@nokia.com wrote:
> >
> > >
> > >Colleagues,
> > >
> > >The folks from the IETF have been saying that the IS consuming more
> > >bandwidth is not a problem, while the IEEE folks are saying bandwidth
> > >and latency are key concerns. We need some meeting of the minds and
> > >implementations/empirical data to help out here.
> > >
> > >Best Regards,
> > >Michael
> > >
> > >-----Original Message-----
> > >From: ext Qiaobing Xie [mailto:Qiaobing.Xie@MOTOROLA.COM]
> > >Sent: Tuesday, October 18, 2005 3:11 PM
> > >To: STDS-802-21@listserv.ieee.org
> > >Subject: Re: [Mipshop] Re: Architectural Considerations for Handover
> > >InformationServices (was: Re: CARD Discussion Query Discussion)
> > >
> > >Yoshihiro Ohba wrote:
> > >...
> > > > - In reality, 3GPP2 has XML-based method (e.g., XCAP) in its
> > > > dependency list.
> > >
> > >If I remember it right XCAP/XML is used there for maintaining the
> > >address book/buddy list that sort of things. I can imagine that sort of
> > >events only happen at most no more than a few times a day for any given
> > >user and probably only happen when the user is NOT in a call. In
> > >contrast, IS query/response likely will be part of the h/o call flow...
> > >
> > >regards,
> > >-Qiaobing
> > >
> > > >
> > > > Yoshihiro Ohba
> > > >
> > > >
> > > >
> > >
> >
> >
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>