7 Apr
2015
7 Apr
'15
6:15 p.m.
Hi Dominiq,
I am trying to remove l1 on both sides and connect
OsmoBTS with BB application via simple unix sockets.
...
Currently I am able to handle messages between BTS and
TRX driver on clock and control ports
...
The thing is that I need to send to BB phone (layer23)
messages in structures from gsm_04_08.h (i.e. gsm48_system_information_type_3).
I am not sure if I will be able to get needed from the
messages coming on the data port 5702.
You are correct. The data port UDP messages carry burst data - that is data after
convolutional encoding and interleaving as well as training sequence insertion, padding
etc... You would have to very inefficiently decode all this again to retrieve the CSN
data bits you seek, though you could then stimulate the timing advance and power control
loops.
I found, that PCU creates unix socket on
“/tmp/pcu_bts” , but only in case sysmoBTS is in use (please correct me if I am wrong),
For non-sysmoBTS there is a different socket, TCP or UDP - I forget, but that's why
you don't see the SEQ_PACKET Unix socket in /tmp for the other config. Check
sysmo_sock.cpp vs openbts_sock.cpp.
So basically I need somehow to get this message
structures on my custom l1 BB interface.
Do you have any idea how to do this ?
I'm no expert, but depending on your ultimate goal you may have some luck pulling them
out of the GSMTAP interface. You can view this using Wireshark to quickly see if it is
enough. Check the docs or source on how to set this up and view it.
Alternatively, using the trx branch, you could try implementing a custom l1. Check around
the bts_model/l1sap code for the software interface (which is shared between the code in
osmo-bts-sysmo and osmo-bts-trx). That's probably a fair bit of work but gives you a
lot of flexibility.
Kind Regards,
Mike