Virtual layer 1 - Questions

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Sebastian Stumpf sebastian.stumpf87 at googlemail.com
Sun Feb 12 13:29:05 UTC 2017


Hi,

The virtual layer 1 is currently in a state where the l23 app can
successfully connect to the bts and most of the signaling messages
will be forwarded and handled. TCH is not yet implemented.

I have some problems still, not knowing if these are caused by
configuration problems or my coding :).

- Trying to initiate a call via the mobile vty will result in
VTY:
 call 1 123
 OsmocomBB#
 % (MS 1)
 % Call has been rejected
 call 1 123
 OsmocomBB#
 % (MS 1)
 % Call has been released
And no actual call setup message is transfered over the Um interface.
What could be reasons for that? I am using the test-sim option the
mobile app offers.

- Occasionaly the T3210 timer is fired, which causes a new registering
within the network.
LOG:
 gsm48_mm.c:336 timer T3210 (loc. upd. timeout) has fired
How can i prevent that?

- I did not implement a tdma or multiframe scheduler in the mobile
uplink as the logical channel is directly put to the gsmtap-header and
thus known by the bts. As Harald used a multiframe based scheduling
for the bts downlink, i wonder if this might be necessary, though. To
submit msgs with the correct frame number for example.

- In my wireshark capture files, the gsmtap messages sent over the
multicast sockets are only recognized as UDP messages. I have to
"cast" them with the wireshark context menu "Decode as...". Why?

I would be super happy if someone of you could check out my project
(osmo-bts, branch stumpf/virt-phy + osmocom-bb, branch
stumpf/virt-phy) try to run it with the config files lying within the
project folders and tell me the problems they see :).

Here you can find a wireshark capture file of 2 mobiles connecting to
a virt bts. I also tried to init calls from both of them but the call
setup is not send.
https://www.dropbox.com/s/2ccky4ljc8ngahz/mobilex2--ms-virt--bts-virt--bsc-nitb_171002%3Asubscribers-accepted-by-nitb.pcapng?dl=0

Kind Regards,
Sebastian Stumpf



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