Subject: Re: [MOBILE-IP] Differences between the two MIPv4 handoff approac hes

From: "Karim El-Malki (ERA)" <[email-masked]>
Date: Tue, 10 Oct 2000 12:04:41 +0200

Hi Pete

> Now, in today's cellular systems, the interval between these two
> events (let's refer to it as [a,b]) is hard and well-specified.  [a,b]
> is so small that the *very next message* sent after (a) is the "do
> handoff" message sent to the MS.  The MS then *immediately* tunes to
> the new BS and the handoff is completed or the call is dropped, in
> case the MS cannot tune to the new BS.  The hard deadline comes from
> the fact that the signal strength to the current BS is rapidly
> degrading, presumably because the MS is moving away.

Here is where I don't agree with your basic assumptions. Some systems
(CDMA-based) don't have such a hard deadline since there is no strict
geographical limit beyond which the MN is unreachable. Some L2 procedures
and messages go on between event a and event b. So this doesn't stop us
from synchronising L2 and L3 procedures. Also, a BS coverage area
is not the same as a MIP FA coverage area and a L2 handoff doesn't
imply a L3 handoff.

> Now, the Proactive draft assumes that we will live with this state of
> affairs for the forseeable future, and allows the L2 messages (the
> power indications leading to (a), and the handoff command implementing
> (b)) to run unchanged.

We don't imply that they will be changed either, but what we are
concerned with is the communication/interworking between L2 and L3,
while maintaining the RFC2002 approach.

> Now whether there is time for these messages to run over-the-air is
> debatable; it may be the case that for some handoffs, the signal
> strength is not degrading quickly enough to cause the disconnection
> to happen prior to the Registration Request.  But that is not really
> my point.  My point is that the Registration Request is generated by
> a non-real-time piece of L3 software on the MN, which might actually
> be running on a laptop computer connected to a phone.

I don't believe we can get away with (or want) such total independence
between L2 and L3 in the future wireless systems which the v4 handoffs
team was working towards. Do you?

Regards,
Karim

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From: WANG Wooi Ghee <[email-masked]>
Date: Tue, 10 Oct 2000 20:57:10 +0900

Hai all

   I would like to know that whether there is any
work been done on addressing in Mobile Ad Hoc Network ?

ghee