Re: What's the benefit of L2 Triggers in 3G/Ad-Hoc systems ?

Hello Kamesh,
  
--- Kamesh Medepalli <[email protected]> wrote:
.... 
> 
> Could one of the proponents of this issue refer me
> to any work that quantifies
> the merit of such a scheme for 3G and/or Ad-Hoc
> systems?
> 
> For the 3G systems (CDMA2000/UMTS) you would most
> probably terminate the
> IP connection at the PDSN/GGSN (more like HA in
> Mobile-IP) and then run
> a PPP link to the Mobile. Now, handoffs are done
> much further away from
> PDSN/GGSN and clearly, the latency is too much for
> us derive any benefit
> from any L2 info. Even if you do have that info fast
> enough, you cannot
> do much at IP layer since the Radio Access Network
> works some-what like a 
> circuit. You do not perform any routing to the
> Mobile beyond the PDSN/GGSN. 
> You just tunnel the PPP frames through GRE, GTP
etc.> 
> I am curious about any work performed in this
> area...
> 
I can probably refer you to NTT-DOCOMO USA labs recent
work on this. In collaboration with Motorola, they
experimented in implementing Mobile IPv4 fast handover
draft which contains L2 Handover triggers. I think
that Motorola implemented the triggers on a CDMA2000
1X RTT radio and PDSN and they used it to get some
benchmarks of handover. 
  Recently James Kempf made a presentation at IPCN02
in Paris and his presentation can be found at:
http://www.mplsworld.com/ipcn02/
look for James Kemp's presentation here.
  Also we wrote a paper which appeared at IEEE
Communications Magazine's May 2002 issue on how L2
triggers including paging triggers can be implemented
using CDMA 2000 entities.
  Yes you are absolutely right on your assessment that
the benefits in real-time gains would probably be
minimal which suggests looking for better radio
architectures and ways of having Mobile IP function
closer to the base station in public cellular networks
is needed.

> Thanks,
> Kamesh

Regards,

--behcet

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