Cellular Network Infrastructure » Radio Access Network » OsmoBSC

= Troubleshooting =

== Known problems with the LMT connection ==

Problem:

'bs11_config' can't get a connection to the BS-11 (no 'LMT LOGON: ACK')

Solution:

The BS-11 is a little bit choosy about the RS232 levels, I discovered some problems 

with my Dell PC (could receive anything, but no tx). Just switch to an el-cheapo USB

to Serial adapter, this should solve the problem.

Some background notes:

We measured the RS232 levels and we found out that the level of our RS232<==>USB Adaptor

is much lower (about +/-6 Volts) than normaly expected (+/-12V). The BS11 transmits at a

semeliar level (about +/-8 Volts). This may be an explaination why the BS11 does not like

the normal (+/-12V) levels. 

[[Image(Lmt_bts-rx.jpg, 15%)]] [[Image(Lmt_bts-tx.jpg, 15%)]] [[Image(Lmt_btx_tx_does_not_work.jpg, 15%)]]

From left to right: BTS-RX (PC-TX), BTS-TX (PC-RX), BTS-RX (PC-TX) with a real RS232 port.

== The "everything looks good - nothing works" - problem ==

When you use openBSC with early mISDN drivers (<= 2.6.31, patched) your setup might refuse

to work while everything looks normal. No error messages, normal PLL Work Value Abis Link

works perfect but no phone can see your network.

Than the first thing you should do is to upgrade your kernel to get the latest mISDN drivers.

Note: When your BS11 is out of Sync the setup also refuses to work. In this case you sould sync your BS11 as described in the isdnsync-howto. 

See also:

http://lists.gnumonks.org/pipermail/openbsc/2009-August/000783.html

== E1 Card System does not recognize the E1 Card ==

Your E1 Card will not be recognized by the System. It does not appear in lspci, nor in the BIOS output when the system starts. In this case the problem is surely that your E1 card is configured to use the 3,3V PCI-Bus supply but your System has only a 5V PCI-Bus supply.

[[Image(jughanns_E1_power_select.jpg, 40%)]] 

In this case the solution is to Change JP3 on the card so that the Card uses its internal 3,3V Voltage regulator. The image above shows a card that is configured to use the 3,3V from the PCI-BUS. It will not work in a pure 5V PCI-Slot.

== The MS sees the network but can't login and there nothing visible on the console ==

We discovered that some SIM cards refuse the login into the network. In this case the MS does not even try to do a location update. You will get the "Not allowed" message immediately. That is also the reasoen why you do not see any requests on the openBSC console. You should try again with another SIM.