paging priority

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Harald Welte laforge at gnumonks.org
Wed Aug 9 14:10:54 UTC 2017


Hi Robert,

On Wed, Aug 09, 2017 at 04:52:39PM +0300, robert wrote:

> Actually its not a busy cell, I only have two MS connected to it and
> the rest of MS trying to connect are rejected. But the problem is that
> the channels are being exhausted while rejecting the other MS. 

So you're not talking about paging load or paging priority here.

What you're experiencing is SDCCH exhaustion due to high number of
concurrent accesses.

> I only have one MS being paged in the cell but it is not always doable
> because of the high load. 

The *paging* is for sure doable, as the paging channel is empty if
you're only paging a single MS.

> If I may ask the question in another way, is it possible to prevent
> this load by just ignoring the location update of certain MS instead
> of responding to them and rejecting them ?

No.  You don't know from whom a given request is, and that it actually
is a location update, until you have established a dedicated radio
channel at L1 + L2 and are receiving L3 signaling messages.

This general problem is about fundamental aspects of the GSM radio interface,
not really related to Osmocom.  There are various different solutions,
such as using SIM cards with specific access classes, making sure your
downlink signal doesn't even reach all those other MSs, properly
configuring the reject causes to make sure they permanently go away,
gradually ramping up transmit power upone enabling the cell, gradually
ramping up access control classes of the cell, using cell barring + MS
with cell-bar-override, etc.

-- 
- Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
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