Subject: Re: [MOBILE-IP] peripheral concern

From: Roberts Phil-QA3445 <[email-masked]>
Date: Mon, 1 May 2000 08:32:20 -0500

Hi,

        I think it's time to reign in this discussion.  We're pretty far off
topic of mobile ip.  Perhaps someone would like to create a cellular
interest list, but designing cellular systems in general and the wide range
of topics associated with it are out of scope.

Phil

-----Original Message-----
From: Theo PAGTZIS [mailto:[email-masked]]
Sent: Friday, April 28, 2000 5:26 PM
To: [email-masked]
Subject: [MOBILE-IP] peripheral concern

I do not know how much has concerned you but,

does anyone have any arguments about health and safety issues in
deploying such BSs ? Are there any issues involved with range extension
antennas that we would like to be aware of?

I am trying to convince people here about their safety but dunno where I
stand... (I know about inverse square.....)

Theo

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From: Theo PAGTZIS <[email-masked]>
Date: Mon, 1 May 2000 18:17:51 +0100

> of topics associated with it are out of scope.

Not really that far....

Considering the small range of the WLAN base stations and the need for dense
population of Base stations for wireless (which is really the major card in the
game called mobility), I think that one needs to consider the effects that the
deployment of such population of base stations will have to humans. Besides the
latter are consumers of the technology (effected by mobile ip) which if not
accepted, won't get far Mobile-IP either....

Positioning of the BS has a direct effect on the BS population per square
mile...but this is directly controlled by the effect it has on humans....(If
you feel threatened by the technology you may always avoid using it....so
practicing of mobile-IP gets another good delay which we could all do _without_
...)

The density of the BS population affects directly the amount of cell handoffs
(which is what mobile-IP _is_ currently concerned with) ....which leads me to
believe that the health and safety effects on humans by the deployment of BSs
controls implicitly cell radius and thus handoff rates....

Since at the moment Mobile-IP cannot overprovision for handoff rates...I think
it would be wise to consider all influencing (albeit peripheral )
factors...before ignoring the issue...

Theo

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From: Amanda Walker <[email-masked]>
Date: Mon, 1 May 2000 13:35:02 -0400

> deployment of such population of base stations will have to
> humans.

On the other hand, WLAN base stations tend to be less dense and *much* lower
power than, say, a room full of people with cell phone handsets (thanks to
operating in unlicensed bands)--we're talking only tens of mW even if you're
sitting directly on the antenna :-).  The average microwave oven, even with
all of its shielding, will swamp out a WLAN operating on the same frequency.

I agree that RF safety issues are not directly relevant to MIP, though they
might be a practical consideration to people constructing networks using RF
physical media, WLAN-based or not.

Amanda Walker <[email-masked]>
Lucent Technologies InterNetworking Systems

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From: Gerald Maguire <[email-masked]>
Date: Mon, 1 May 2000 19:54:20 +0200

Actually if what you are concerned about is the power level which an
individual is exposed to, then the smaller the cells the better
(atleast down to a single user per cell). In the case of only one user
per cell, there only needs to be a signal in this cell if _this_ user
wants to communicate. In addition all the signalling is _only_ that
which the user wants, so if they don't want something there is no
reason to transmit to them, hence the exposure can be as low as
practical to carry out this user's communication needs.

A side effect of this approach is that non-users have very little
exposure.

Note that as cells may not have infinitely sharp fall-off, there is
energy radiated outside of the cell. However, it benefits the system
designers to minimize this -- since it decreases costs, limits
interference, increases capacity,  ... .

In a similar fashion mobile devices will want to radiate as little
power as possible to accomplish their communication task, since this
will reduce their power requirements and hence reduce battery weight
or increase battery life.

You have stated that "Since at the moment Mobile-IP cannot
overprovision for handoff rates..."  but this is not true, in fact the
solutions proposed by Vatn and Wu both demonstrate that you can think
of a user moving through space as creating a bow wave and a trailing
wake. The bow wave corresponds to simulcasting additional copies of
packets to the cells that the user is most likely to enter next, while
the trailing wake consists of the copies being sent to where the user
used to be. Depending on the speed of the user in comparison to the
time delays involved in establishing and terminating routing of
packets these waves will be larger or smaller. As the user's velocity
vector decreases in magnitude the effects (both fore and aft) become
smaller. At high acceleration the effects of the user's movement are
most widespread and the total system emergy used is high, but at zero
acceleration (but constant velocity) the energy used will be directly
related to the delays in control signaling {assuming a homogeneous
cell structure}.

In heterogeneous systems with different sized cells there will
probably be "critical" velocities and accelerations which trigger
vertical handoffs.

Chip

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From: Theo PAGTZIS <[email-masked]>
Date: Mon, 1 May 2000 19:36:28 +0100

> practical to carry out this user's communication needs.

I think that a cell with a single user is rather a scenario that would
not meet real world practice. And for the sake of completeness I do not
refer to PANs but WLANs....

> overprovision for handoff rates..."  but this is not true,

Perhaps I was unclear, what I mean is that fast handoffs at the moment
are an issue for Mobile-IP.. to require fast handoffs you either
need to have too many small cells (constant velocity) or keep cell size
the same and increase velocity, or both.

I was refering to the first case only...

So going back to original question: "What are the link layer hints that
MIP _may_ want to be aware of, to effect handoffs successfully in terms
of performance or other"?

Should or shouldn't MIP keep independent of link layer considerations.
Would the spec like to encourage awareness but enforce it?

What is the precedence that PPP has established (if any) - on link layer
hints?

Theo

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From: Gerald Maguire <[email-masked]>
Date: Mon, 1 May 2000 21:15:03 +0200

I disagree with respect to the definition of PAN -- I would think that
the PAN is the network which moves with me when I move, while a
femtocell of a WLAN is a cell that just encompasses me and perhaps a
few things very near to me. As I can move through a considerable
number of such very small cells over the course of a day, I will want
Mobile IP support for many of the devices which move with me.

I seem Mobile IP as providing the mechanims, but that an external
agent should provide the policy of when to do handoffs and to whom.
The question then becomes how the agent is going to tell Mobile IP its
decisions and how Mobile IP can indicate that it needs a decision and
provide some of its current observations.

With respect to observations, it would see that via (SNMP) access to
the Mobile IP and interface MIBs that we should be able to access all
the externally observable behavior/information.  This enables the
agent to be local or remote (however, if the agent is remote it must
be able to act only when there is connectivity to the mobile and the
mobile will need some fall back behavior -- much as space probes have).

What I'm unclear on is how the agent should tell Mobile IP its
decisions. Should this be via manipulating the Mobile IP MIB or via an
API (much as configuring routers can be done via SNMP or a command
line interface).

Chip

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From: Theo PAGTZIS <[email-masked]>
Date: Mon, 1 May 2000 20:34:34 +0100

Chip,

    I tried to keep silent after Rob's call for adherence to MIP only
issues...

> the PAN is the network which moves with me when I move,

If the network moves with you....it smells like Adhoc nets....unless you refer

to devs that move but only in the same cell ...

Do you feel that it should be pure MIP that should cater for these small nets
...sort of Bluetooth  PANs with an attitude nets...I think it may want
something
more lightweight...

> while a

smells like admission control....in that case you may want to set a policy
enforcment point talking with BSs....or better the FAs that
would control entry through the BS..

Theo