Extend the router to verify that the message received is
properly encoded. The code can deal with the basic structure
of ETSI OML and vendor specific messages for ip.access and
the osmocom project.
Currently ADM state change request that tries to set the
administrative state to the current value are immediately ACK'ed.
Beside the caching problem, this could lead the protocol
inconsistencies if two such requests are sent one after the other and
the second arrives before the procedure of the first has finished.
This patch removes the shortcut in oml_rx_chg_adm_state() which
immediately called oml_mo_statechg_ack(mo).
Ticket: OW#1132
Sponsored-by: On-Waves ehf
These routines do not pass the gsm_abis_mo and parsing the FOM
header of the msg does not seem to be a good idea either. Pass
in the OML object so that the model code can determine what the
void pointer is.
This way, bts_model_check_oml() can return a negated NM_NACK_* constant
which will then be sent as cause value in the corresponding
SET_ATTR_NACK back to the BSC.
Currently a Change Administrative State Request is just applied
unconditionally to the object's state object and then acknowledged.
This patch implements the special handling of setting the Radio
Carriers state to LOCK or UNLOCK. This is done by passing the
appropriate mute command to the L1 layer. Always all radio channels
are affected, it is not possible to lock single radio channels.
On success, an ACK is sent back to the bsc with the new state (based
on the state passed in the callback by the L1 layer). If something
went wrong or the firmware doesn't support RF mute, a NACK
(REQ_NOT_GRANTED) is sent instead.
Note that a NACK for such a request hasn't been sent by the BTS to
the BSC yet, so (albeit it's spec conformant to do so) the BSC must
be prepared to handle this correctly.
Ticket: OW#976
Sponsored-by: On-Waves ehf
This introduces a new get_signlink_remote_ip() function whcih we also
use in the RSL code to determine the RTP remote address if the CRCX/MDCX
contains no remote IP address IE.
libosmoabis has a BTS-side implementation of the IPA protocol for years,
and osmo-bts should have used that all the time. Unfortunately it had
its own local hack, this patch is migrating to the libosmocore
implementation.
Instead of calling oml_mo_state_chg() [which transmits OML STATE CHG]
during bts_init(), we use a new oml_mo_state_init() function which
simply sets the state.
In case that the counter S reached 0, it will stay 0. Subsequent received
good and bad SACCH frames must not cause to trigger radio link failure
again. Once the BSC has been indicated about link failure, it will release
channel.
The counting of S has been moved to a seperate function.
This patch will ensure that the link failure is indicated only once. But
even if the link failure would be sent multiple times, the BSC should
ignore it. The BSC releases the channel and may only reuse it after confirm
from BTS. (There cannot be any link failure indications after confirm of
channel release.)
The allowed timeout value range is 4..64, as defined in TS 05.08, so if the
BSC sends an attribute with value out of range or other failure criterion,
the Set BTS Attributes message is NACKed.
Chapter 5.2 applies to MS procedure, but 5.3 (BSS procedure) defines no
exact criterion, so I decided to use the procedure equivalent to MS.
The criterion is based on a counter S, which is initialized to a preset
RADIO_LINK_TIMEOUT, which can be configured via VTY. Whenever a received
SACCH block is bad, S is counted down by one. If SACCH block is
successfully decoded, S is counted up by two, but never above initial
RADIO_LINK_TIMEOUT value. If S reaches 0, an RSL Connection Failure
Indication with cause RF Radio Link Failure is sent to BSC, which then
aborts channel.
Use link timeout value from BSC via OML attribute.
How to test:
- Set "debug" for "meas" logging.
- Start silent call to an attached mobile.
- Remove battery from mobile or shield mobile.
- Watch S count down.
This allows us to do RF measurements (EDGE EVM and the like) even
without having any PCU/RLC/MAC code as of now.
To use it, configure PDCH type timeslots (e.g. TS 7) in the BSC and then
use "trx 0 7 activate 0" to manually activate the PDTCH lchan on top
of that timeslot. The BTS will now happily transmit EDGE/8PSK data.
Use 't' modifier for pointer diff in the printf statement.
oml.c: In function ‘oml_rx_set_bts_attr’:
oml.c:403:3: warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 9 has type ‘int’ [-Wformat]
We have to
* merge the new attributes with the exiting TS (not BTS) attributes
* in case of success, attach the new merged attributes to our state
* in case of success, free the old attributes
Thanks to Holger for pointing this out.
The sequence is as follows:
0) start osmo-bts
1) start connection attempts to BTS
2) issue L1-RESET.req
3) receive L1-RESET.conf
4) issue RF-ACTIVATE.req
5) receive RF-ACTIVATE.conf
6) receive attributes for TRX
7) receive opstart for TRX
8) issue MPH-INIT.req
[...]
The important point here is: We don't want the BSC to set TRX attributes or do
TRX opstart before our RF related hardware is initialized.
In SDCCH4, we use lchan number 0...3 for the SDCCH/SACCH, and
we statically use lchan[4] as the dummy for activating the CCCH
L1 SAPIs.
In order to make combined and non-combined CCCH orthogonal, we simply
also use lchan[4] in that case. On a 'pure' CCCH, therefore lchan
0..3 are unused and 4 is the actual CCCH.
This code re-works osmo-bts to add support for the upcoming sysmocom BTS.
It also tries to add some level of abstraction between the generic
part of a BTS (A-bis, RSL, OML, data structures, paging scheduling,
BCCH/AGCH scheduling, etc.) and the actual hardware-specific bits.
The hardware-specific bits are currently only implemented for the sysmocom
femtobts, but should be (re-)added for osmocom-bb, as well as a virtual
BTS for simulation purpose later.
The sysmocom bts specific parts require hardware-specific header files
which are (at least currently) not publicly distributed.
Holger Hans Peter Freyther
Harald Welte