Until 2009 the situation looked like this:
In 2008, some people (most present in this room) started to write FOSS for GSM
bs11-abis
to bsc_hack
to OpenBSC
Mobile Station (your phone)
Base Transceiver Station, consists of 1..n TRX
Transceiver for one radio channel, serves 8 TS
Timeslots in the GSM radio interface; each runs a specific combination of logical channels
Base Station Controller
Mobile Switching Center; Terminates MM + CC Sub-layers
Home Location Register; Subscriber Database
SMS Service Center
Link Access Protocol, D-Channel. Like LAPD in ISDN
Radio Resource (establish/release dedicated channels)
Mobility Management (registration, location, authentication)
Call Control (voice, circuit switched data, fax)
Connection Management
We assume a sysmoBTS in the following tutorial
osmo-bts-sysmo
: BTS family by sysmocom
osmo-bts-trx
: Used with OsmoTRX + general-purpose SDR
osmo-bts-octphy
: Octasic OCTBTS hardware / OCTSDR-2G PHY
osmo-bts-litecell15
: Nutaq Litecell 1.5 hardware/PHY
See separate talk about BTS hardware options later today.
⇒ Make sure you permit the above communication in your network/firewall config
configure terminal
and interactively change it
/etc/osmocom/osmo-bts.cfg
as
described in the following slide
bts 0
band DCS1800 <1>
ipa unit-id 1801 0 <2>
oml remote-ip 192.168.100.11 <3>
the GSM frequency band in which the BTS operates
the unit-id by which this BTS identifies itself to the BSC
the IP address of the BSC (to establish the OML connection towards it)
Note
|
All other configuration is downloaded by the BSC via OML. So most BTS settings are configured in the BSC/NITB configuration file. |
⇒ BSC identifies BTS on Unit ID, not on Source IP!
git clone && autoreconf -fi && ./configure && make install
libosmo*
dependencies are required first…)
doc/examples/osmo-*.cfg
of each git repo
→ let’s check if we can perform LOCATION UPDATE on our own network
logging level mm info
→ should show LOCATION UPDATE request / reject / accept
show *
)
*#100#
from any registered MS to obtain own number
show
commands)
Program |
Telnet Port |
OsmoBTS |
4241 |
OsmoBSC |
4242 |
OsmoMSC |
4254 |
OsmoHLR |
4258 |
?
and list
commands
show
commands to introspect
show bts
, show trx
, show lchan
, show statistics
, …
enable
+ configure terminal
for configuration mode
logging enable
adds log target to VTY session
osmo-mgw
acts as RTP proxy, both at BSC and at MSC level
See https://osmocom.org/projects/cellular-infrastructure/wiki