Subject: [MOBILE-IP] intra-RAN diversity with dynamic anycasting...

From: Theo PAGTZIS <[email-masked]>
Date: Thu, 4 May 2000 19:07:30 +0100

It strikes me that we should not be talking about macrodiversity but
microdiversity since the terms really refers to intra-RAN movement, not
inter-RAN one.

I cannot see how you intend to effect power control on the MN since you
have no control over the mobility pattern of the MN. For instance lower
power on the MN may be effected if the MN is relatively close to the BS
and the air interface is relatively quiet. I would probably opt for the
word 'compliance' to power transmission requirements based on
(distance,velocity,height,direction) vector. The degree of compliance to
power control on the BS should be affected in some non-linear way by
that vector.

When you try to eliminate cell dragging (inter or intra-RAN) isn't there
a limit to how many cells a CDMA node can be in contact with?

How do you decide which BS will participate on the simulcasting of the
radio frames and thus will receive  the attention of the RAN gateway. Is
the participation dynamic per-RAN or is it fixed (you mentioned point to
point links). If it is fixed don't you introduce a point of failure for
the BS in case the RAN gateway gets down...?

There may not be a one to one mapping but I gather that you would like
the one (MN) to many (BS) down to a minimum....otherwise you flood your
link towards the RAN gateway...

Theo

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From: Pete McCann <[email-masked]>
Date: Thu, 4 May 2000 14:05:09 -0500

Hi, Theo,

Theo PAGTZIS <[email-masked]> (TP) writes:

TP> It strikes me that we should not be talking about macrodiversity but
TP> microdiversity since the terms really refers to intra-RAN movement, not
TP> inter-RAN one.

I am not sure where the term "macrodiversity" comes from - I think it
is a 3GPP term.  Frame selection (what I usually call it) can occur
both within and between RANs - sometimes BTSs from a neighboring RAN
are "borrowed" and added to the active set of BTSs.

TP> I cannot see how you intend to effect power control on the MN since you
TP> have no control over the mobility pattern of the MN. For instance lower
TP> power on the MN may be effected if the MN is relatively close to the BS
TP> and the air interface is relatively quiet. I would probably opt for the
TP> word 'compliance' to power transmission requirements based on
TP> (distance,velocity,height,direction) vector. The degree of compliance to
TP> power control on the BS should be affected in some non-linear way by
TP> that vector.

The RNC does not have direct knowledge of the position, velocity, and
acceleration of the MN.  What happens in existing systems are that the
MN sends a signal to the RNC whenever the detected pilot level of some
BTS in its candidate set exceeds a given threshold.  Then the RNC has
the option of adding that BTS to the active set.  Power control is
maintained by watching the error rates and adjusting the transmission
power of each BTS to keep it within a predefined threshhold.  The IP
stack on the MN is unaware of any of this activity (and should remain
so).

TP> When you try to eliminate cell dragging (inter or intra-RAN) isn't there
TP> a limit to how many cells a CDMA node can be in contact with?

Yes, there is a limit, and it varies from system to system.

TP> How do you decide which BS will participate on the simulcasting of the
TP> radio frames and thus will receive  the attention of the RAN gateway. Is
TP> the participation dynamic per-RAN or is it fixed (you mentioned point to
TP> point links).

Participation of BTSs is done according to an algorithm like that given
above.  BTSs in an active set can sometimes belong to two different RANs.

TP> If it is fixed don't you introduce a point of failure for
TP> the BS in case the RAN gateway gets down...?

The RAN gateway is in fact a single point of failure because it is the
attachment point to the rest of the network.  This is true of any of
the equipment in an IP network between you and your first-hop gateway
router, such as your modem, your telephone line, and the NAS box you
are connecting to.

TP> There may not be a one to one mapping but I gather that you would like
TP> the one (MN) to many (BS) down to a minimum....otherwise you flood your
TP> link towards the RAN gateway...

Not quite sure what you mean here - you should add BTSs to the active
set to achieve the desired level of reliability on the link.  Adding too
many would of course add to network utilization.

-Pete

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From: Theo PAGTZIS <[email-masked]>
Date: Thu, 4 May 2000 20:37:51 +0100

> are "borrowed" and added to the active set of BTSs.

Fine but I thought that the draft argues on the case of intra-RAN movements and
subsequent effect of
handoff smoothening...If you start borrowing (hello CBQ)  BTSs from
neighbouring RANs (really recruit other RANs services) then you
are making the distinction between intra and inter-RAN movement a bit obscure.
For instance how do you actually decide that you should borrow a BTSs
for the neighbour RAN and not initiate a hard handoff? The picture becomes a
bit like expanding/contracting (living) RANs....

> stack on the MN is unaware of any of this activity (and should remain

Fine ! that mean that by manipulating your power thresholds per MN you may be
able to pass MNs to neighbouring cells and really be in control (as RAN
gateway) of the handoff situation....So it looks like the MN kicks the handoff
but really it is the RAN gateway that  triggers it. This has some nice angles
in terms managing hotspots and really resources...but isn't that getting the
handoff really as network initiated...???

> router, such as your modem, your telephone line, and the NAS box you

I thought that if the BTSs participates to more than one RAN gateways it could
potentially re-elect a new RAN-gateway master and thus avoid
such PoF. That of course requires that one such BSs maintains more than one PtP
connections with diff RAN-gateways; could that have negative implications for
the RNCs ?

> many would of course add to network utilization.

I may have not understood things correctly here...How long is the 1-M rel/ship
between MN and BTSs,  effected for ?

Theo