Need help with configuration of Timeslots and of multible USRPs

[Norbert Englberger]

Hello again, 

Holger Hans Peter Freyther wrote:

> it is not a question of BTS but the BSC. The role of the BSC is to manage
the
> channels. Inside src/libbsc/gsm_04_08_utils.c you will see a table that
> determines how the BSC/NITB will respond to "channel request" inside the
> RACH request by the phone.
> 
> E.g. if you change get_ctype_by_chreq to always return LCHAN_SDCCH you
> should be close to the behavior you have described.
> 

First off all: Thank you for your fast response.

I was hoping that it would be enough to change the settings in the
open-bsc.cfg and I wouldn't have to temper the source code, as I said, I'm
new to all the GSM stuff and Linux.

I had a quick look at the code and just tried to comment out everything in
"get_ctype_by_chreq" and always return LCHAN_SDCCH as you suggested.

While testing this setup I saw, that The "Immediate assignment" now sends
the calling MS to TS 1 (which is configured as SDCCH/8) subslot 0 and
starts encryption and sends SI5 and SI6 messages on this timeslot/subslot.
Also the called MS gets "Immediate assignment" and is sent to TS 1 subslot
1, encryption starts and so on.
Now the called MS sends "Call Confirmed", but shortly after this the
channels are released. (The called MS wasn't ringing at all)

Am I right, that this is because both MS are yet sticking on the SDCCH and
are not going to a Transport channel? (would make sense, because I always
return SDCCH when the BSC wants to change channel)

I think I have to change the Table " ctype_by_chreq" or to find a way to
insert another "Immediate Assignmend" between "encryption" and "call
confirmed"

So I think I'll have to study the source code for a while,

Again thanks for the hint where to start.  

[Norbert Englberger]