how to stop paging

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Neels Hofmeyr nhofmeyr at sysmocom.de
Thu Mar 2 19:38:39 UTC 2017


I have a general question about the Paging procedure, specifically about
how to stop paging.

In libbsc, we have Paging management that receives a request to Page from
the MSC and then repeatedly Pages the MS on all BTSes N times or until
told to stop.

In the NITB, we have code closely tied to the BSC and all BTS management,
so that when we receive a Paging Response, we can right away stop sending
Paging Commands on all BTSes.

So can the standalone-BSC: it stops paging when it received a Paging
Response.

In OsmoMSC with Iu- and A-interfaces, that's not possible. Looking in
08.08, there seems to be no A-interface message that tells the BSCs "thank
you, you can stop paging now". If one BSC or RNC has relayed back a Paging
Response from one of the cells, the MSC has no way to tell the other base
stations that it's fine to stop sending dozens of Pagings out for
"minutes", which would be useless now anyway because the MS has called
back via another base station already.

Is that a fact of life? We continue Paging in all cells where the MS is
not visible? Should the BSC/RNC part of the network page only once, so
that "stop paging" is a no-op?

Of course we first check which LAC the MS was first seen on and page only
there. Is the idea to send paging to one cell, and that cell stops Paging
by itself when it received a Paging Response that it relays to the MSC?

But IIRC Paging is supposed to spread out across other base stations if at
first it didn't succeed -- I recall to have read that in HNB-GW specs or
somewhere close to that. Our OsmoHNBGW so far simply Pages everywhere.

The practical reason I'm asking is that in the msc_vlr tests, I so far
explicitly check whether the "stop paging" function was called. Now on the
Iu branch, without libbsc, there is no such function. Should I drop those
checks because we will never have that? Or should I add some shim function
we call just for the tests so far, which will at some point tell the base
stations that Paging has concluded?

Thanks for any hints,

~N


-- 
- Neels Hofmeyr <nhofmeyr at sysmocom.de>          http://www.sysmocom.de/
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