22 Nov
2013
22 Nov
'13
5:03 p.m.
Hi Dominik,
On Tue, Nov 19, 2013 at 01:41:20PM +0000, TAMASKOVIC, Dominik wrote:
I am working on my Diploma thesis , which topic is
GPRS Emulation
software. This project is based on your OsmoBTS project . The idea is
to delete/replace the hw-related primitives and features and redirect
the whole traffic to the osmocomBB with modifications – this is the
work of my colleague .
Where can we track the progress of this work? Are you using a private
git repository somewhere? Please let us know where your code is. You
know where our is ;)
The idea of a virtual air interface between OsmoBTS and OsmocomBB has
been suggested multiple times. The use of GSMTAP for the 'virtual air
interface' has so far been the best conclusion. However, we have not
yet received any contributions in that area.
1st point: My intention is to implement gprs part
only. I have
analyzed the BTS codes(especially Master, Jolly/l1sap_parts and
Jolly/Trx ), i dont know which one will be most suitable to use, but
I think the jolly/trx or jolly/l1sap_parts common part will be
probably best choise . It implements more common functions in l1sap
interface compared to the Master code . Am I right ?
Correct.
2nd point: I have analyzed the common code, and it is
look like the
main logic of the PCU(from the BTS side) is implemented in pcu_sock.c
and l1sap.c , where the l1sap implements the message parsing and
sending to the l1_if of the BTS , and also initializes gsmtap messages
. So what I want to do is to create another socket application to
connect with osmocomBB(with additional gprs implementation) , which
will send/receive the BTS messages from l1sap through our custom "l1
interface" to the osmocomBB phone("how simple") . The PCU part looks,
that would not need any intervention. What do you think ?
I would prefer if you used GSMTAP messages as the 'virtual air
interface'. They are a well-known format for encapsulating GSM Um
interface messages at the L1/L2 boundary. You can even have multiple
TRXs, as the ARFCN is indicated in the GSMTAP header. And if all BTSs
and MSs are using UDP multicast, you can even have multiple BTSs which
are seen by multiple phones, etc.
Also, at that point, you can analyze the full traffic in wireshark.
Regards,
Harald
--
- Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/
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