Hi All,
I've started implementing reception of multiple channels of a BTS as part of my gr-gsm project and I encountered little problem. C0 channel (most probably) uses different training sequence than the rest of ARFCNs from Cell Allocation. I'm not sure that this is the case. But if I compute cross correlation I always get the strongest peak for a different training sequence.
The training seqence number used on C0 is usually equal to BCC (BTS Color Code) that is transmitted in SCH bursts (I've never seen different situation in the wild). I can also find training sequence code of C0 transmitted on BCCH inside of Channel Description in System Information Type 4 messages. Where BTSes transmit training sequence (/sequences) of ARFCNs other than C0?
Best Regards, Piotr Krysik
Hi Piotr,
good to hear from you again :)
On Fri, Sep 05, 2014 at 03:41:16PM +0200, Perper wrote:
Where BTSes transmit training sequence (/sequences) of ARFCNs other than C0?
This should be part of the Channel Description IE of the IMMEDIATE ASSIGNMENT of the specific logical channel on the AGCH in the downlink CCCH. Indeed, each logical channel can have a different training sequence and they do not need to match the BCCH one.
Hi Harald,
W dniu 08.09.2014 o 15:02, Harald Welte pisze:
Hi Piotr,
good to hear from you again :)
I'm just trying to complete some of the TODO's that I left ;). On the sidenote: osmocom is great! Thanks to your efforts mobile communication is not an unreachable mystery it once was.
On Fri, Sep 05, 2014 at 03:41:16PM +0200, Perper wrote:
Where BTSes transmit training sequence (/sequences) of ARFCNs other than C0?
This should be part of the Channel Description IE of the IMMEDIATE ASSIGNMENT of the specific logical channel on the AGCH in the downlink CCCH. Indeed, each logical channel can have a different training sequence and they do not need to match the BCCH one.
Thanks for the answer! I will experiment with autodetection of the sequence used and/or reconfiguration based on information transmitted on AGCH.
Regards, Piotr Krysik
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Harald Welte -
Perper