Remove the paragraph about writing to the Free Software Foundation's
mailing address. The FSF has changed addresses in the past, and may do
so again. In 2021 this is not useful, let's rather have a bit less
boilerplate at the start of source files.
Change-Id: I73be012c01c0108fb6951dbff91d50eb19b40c51
Regarding the removal of burst_mask2str() from the TCH/H handler,
it does not make sense to print it because the mask is already
shifted and an earlier logging should already contain this info.
Change-Id: I42d20e2da73c21ca366dd246244cd716c8ccb459
Related: OS#4823
In a typical setup operating on the real radio interface, it's
the duty of the transceiver (e.g. osmo-trx) to send NOPE.ind to
the L1 implementation (e.g. osmo-bts-trx). However, in a
virtual environment for ttcn3-bts-test we use a fake transceiver,
which due to its simplicity cannot send NOPE indications itself.
The lack of queues and buffering does not allow us to implement
NOPE indications in fake_trx.py, so the easiest approach is to
generate them from trxcon. Send TRXD PDUs without the burst bits,
and fake_trx.py will tranform them info NOPE.ind for us.
Change-Id: I1c7f1315b8ef44f651efd6a22fb5b854f65c0946
Related: SYS#5313, OS#1569
Similar to what we do in osmo-bts-trx, group everything related to
an Uplink burst into a structure. Pass a pointer to this structure
to the logical channel handlers. This makes the code easier to read,
and facilitates sending NOPE indications to the transceiver
(will be introduced in the upcoming patch).
Get rid of sched_trx_handle_tx_burst(), and instead just call
sched_trx_a5_burst_enc() directly from sched_frame_clck_cb().
Change-Id: Id45b27180c233fdc42ae1ef0b195554dd299a056
Related: SYS#5313, OS#1569
158 is basically: 8 + 148 + 2, where the last two are padding bytes
sent by legacy TRXDv0 transceivers. We don't need them, so do not
drop PDUs without these leggacy padding bytes.
Change-Id: I6c0734bc4669ccde2a93940c9cf50fdbbd67cb00
This is what trxcon sends to the network before the first SACCH
block is received from the higher layers. The indicated values
are of course invalid because they're hard-coded.
According to 3GPP TS 44.018, table 10.5.2.20.1:
0 The measurement results are valid
1 The measurement results are not valid
Change-Id: I7da767e146aec7cef1de71e4d735d6a02b6c5642
Related: SYS#4918
Table 10.5.2.20.0 "Measurement Results Contents" in 3GPP TS 44.018
is clear on what should be used as padding - '0**', i.e. zeroes.
Change-Id: I4db6845c98aded10291134f416da98fd0f4f58e3
Previous code relied on abort() switching sigaction to SIG_FDL +
retriggering SIGABRT in case the signal handler returns, which would
then generate the coredump + terminate the process.
However, if a SIGABRT is received from somewhere else (kill -SIGABRT),
then the process would print the talloc report and continue running,
which is not desired.
Change-Id: I6d80f3f2742d397e47f4f2970c951f2cf6d58172
Fixes: OS#4865
The signal handler was coded as if it was handling SIGABRT, but the
signal handler was not overwritten so it is actually used.
Change-Id: I5c597f3410fc97be138db6f3976df59f393819b6
Both REQ and CNF share the same message structure, so we can
cheat a bit by changing the message type and sending it back.
Change-Id: I6f403ed0506b4b1872361d9976d3186bfe514b52
Related: OS#4799
Some commands, such as SETTA or SETPOWER, are expected to be sent
when the transceiver is powered on. We should not drop Uplink
bursts while waiting TRXC response.
For now it's easier to comment out the state check completely,
because the existing TRXC state machine is quite messy.
Change-Id: Iefe6030200b11b29a5790d1f4aa4070ed1d9a493
In general, premature scheduling of to be transmitted bursts
inevitably increases the time delay between Uplink and Downlink.
The more we advance TDMA frame number, the greater gets this
delay. 20 TDMA frames is definitely more than a regular
transceiver needs to pre-process a burst before transmission.
Change-Id: Ia9b142b59d95f2cd7b2394596cf72c0bcd36d711
Related: OS#4487
When running together with fake_trx.py (mostly used back-end), it
is currently possible that Downlink bursts are received in a wrong
order if more than one transceiver is configured (multi-trx mode).
This is how it looks like:
DTRXD DEBUG trx_if.c:612 RX burst tn=3 fn=629 rssi=-86 toa=0
DSCHD DEBUG sched_lchan_tchf.c:60 Traffic received on TCH/F: fn=629 ts=3 bid=1
DTRXD DEBUG trx_if.c:612 RX burst tn=3 fn=630 rssi=-86 toa=0
DSCHD DEBUG sched_lchan_tchf.c:60 Traffic received on TCH/F: fn=630 ts=3 bid=2
DTRXD DEBUG trx_if.c:612 RX burst tn=3 fn=631 rssi=-86 toa=0
DSCHD DEBUG sched_lchan_tchf.c:60 Traffic received on TCH/F: fn=631 ts=3 bid=3
DTRXD DEBUG trx_if.c:612 RX burst tn=3 fn=633 (!) rssi=-86 toa=0
DSCHD NOTICE sched_trx.c:663 Substituting (!) lost TDMA frame 632 on TCH/F
DSCHD DEBUG sched_lchan_tchf.c:60 Traffic received on TCH/F: fn=632 ts=3 bid=0
DSCHD DEBUG sched_lchan_tchf.c:60 Traffic received on TCH/F: fn=633 ts=3 bid=1
DTRXD DEBUG trx_if.c:612 RX burst tn=3 fn=632 (!) rssi=-86 toa=0
DTRXD NOTICE sched_trx.c:640 Too many (>104) contiguous TDMA frames elapsed (2715647)
since the last processed fn=633 (current fn=632)
so here a burst with TDMA fn=633 was received earlier than a burst
with TDMA fn=632. The burst loss detection logic considered the
latter one as lost, and substituted it with a dummy burst. When
finally the out-of-order burst with TDMA fn=632 was received, we
got the large number of allegedly elapsed frames:
((632 + 2715648) - 633) % 2715648 == 2715647
Given that late bursts get substituted, the best thing we can do
is to reject them and log an error. Passing them to the logical
channel handler (again) might lead to undefined behaviour.
Change-Id: I873c8555ea2ca190b1689227bb0fdcba87188772
Related: OS#4658, OS#4546
It's not something that we should be trying to fix, if the whole
TDMA multi-frame is lost. For some yet unknown reason, sometimes
the difference between the last processed TDMA frame number and
the current one is so huge, so trxcon eats a lot of CPU trying
to compensate nearly the whole TDMA hyper-frame:
sched_trx.c:640 Too many (>104) contiguous TDMA frames elapsed (2715647)
since the last processed fn=633 (current fn=632)
Let's just print a warning and do not compensate more than one
TDMA multi-frame period corresponding to the current layout.
Change-Id: I56251d0d2f6fa19195ff105d3bdfbc22df6db8cd
L1CTL is using the network byte order, because this protocol is
spoken between different devices and architectures. Somehow I
forgot about this while adding SETFH command back in 2018.
Change-Id: Ia2f70f0d5e35b6bf05e1fa6fb51a15c1bbe3ca4c
Related: OS#4546
It would make sense to send the ARFCN list in parameters of SETFH
command, if there was a clear distinction between transceivers in
fake_trx.py, i.e. which one is an MS and which is a BTS.
Right now, every Transceiver is an abstract entity that emits
and receives bursts. So when you convert an ARFCN to a pair of
Downlink/Uplink frequencies, you don't know whether it maps
as Rx/Tx or as Tx/Rx for a given Transceiver.
Of course, we could assume that this is an MS specific feature,
and a pair of Downlink/Uplink frequencies always corresponds to
Rx/Tx, but what if some day we would need to implement and test
a similar approach for the BTS side? Also, by sending frequency
values in kHz (rather than ARFCNs) we can avoid inconsistency
with the existing RXTUNE / TXTUNE commands.
Change-Id: Ia2bf08797f1a37b56cf47945694b901f92765b58
Related: I587e4f5da67c7b7f28e010ed46b24622c31a3fdd
Related: OS#4546
Since we're heavily using trxcon in ttcn3-bts-test, the logging
output should contain as much information as possible. Ideally
we should introduce the VTY interface (see OS#3666) and get
logging configuration options as a bonus. But let's just use
some beneficial hard-coded defaults for now:
- print category and level (huh, we use NOTICE everywhere?),
- do not print category-hex (who needs it anyway?),
- print extended timestamp, so we're in synce with other logs.
P.S. This configuration is based on my own debugging experience.
Change-Id: Ie3d259f3255d8af80e6780f850b808fa243f97b4
As was noted by Pau Espin Pedrol, there is a theoretical chance
that lchan->tdma.num_proc would overflow, so as a consequence,
subst_frame_loss() will be unable to compensate one
(potentionally lost) Downlink burst.
On practice, given the size of unsigned long and duration of a
single TDMA frame, it would only happen once in roughly ~6 years.
FRAME_DURATION = 4615 * 10e-6
ULONG_MAX = 2 ** 32 - 1
FRAME_DURATION * ULONG_MAX -> ~198212740 seconds
-> ~55059 hours
-> ~2294 days
-> ~6 years.
Chances are that trxcon would crash much earlier, or even GSM
would be completely forgotten after such a long time run, but
let's work this around and simply start counting from 1
if that overflow eventually happens.
Change-Id: I3d40ef09b06039a85df52af06ab38de314e1a434
It may happen that the burst reception would start from bid != 0:
<0005> sched_trx.c:263 (Re)configure TDMA timeslot #2 as TCH/H+SACCH
<0005> sched_trx.c:420 Activating lchan=TCH/H(0) on ts=2
<0005> sched_trx.c:420 Activating lchan=SACCH/TH(0) on ts=2
<0006> sched_lchan_xcch.c:96 Received incomplete data frame at fn=0 (0/104) for SACCH/TH(0)
<0006> sched_lchan_xcch.c:106 Received bad data frame at fn=0 (0/104) for SACCH/TH(0)
so in that case, both measurement processing and the frame number
calculation would yield incorrect and/or incomplete results. The
Rx burst mask can be used to eliminate this problem.
In particular, if we shift it left instead of cleaning, it would
never be equal 0x00 after at least one burst is received. This
would allow us to skip decoding of an incomplete frame at the
beginning when the logical channel was just activated.
Note that TCH/H handler is not affected because it already uses
the strategy described above, so we keep it unchanged.
Change-Id: Ib8ddf2edd5ef84f2ab12155f7a8874c9fc56d436
Related: OS#3554
It may happen that one or more Downlink bursts are lost on their
way to the MS due to a variety of reasons. Modern transceivers
supporting TRXDv1 protocol would substitute lost bursts with
so-called NOPE indications. Hovewer, neither fake_trx.py nor
grgsm_trx do support this feature at the moment.
We can still detect and compensate TDMA frame loss per logical
channels in the same way as it's already done in osmo-bts-trx.
In short, we should keep TDMA frame number of the last received
burst in the logical channel state, and using the appropriate
multiframe layout, check if there were any gaps between TDMA
frame number of the current burst and the stored one.
Change-Id: I3551d79796a3730565c2c70577e9d134e636f275
Using TDMA frame number of a burst with bid=0 is fine for xCCH,
but not for TCH and FACCH, because they use the block-diagonel
interleaving. A single block on TCH may be interleaved over
8, 4 or even 6 consecutive bursts depending on its type.
Since we now have the measurement history, we can attach TDMA
frame number to each measurement set, and then look up N-th
one when averaging the measurements in sched_trx_meas_avg().
Change-Id: I9221957297a6154edc1767a0e3753f5ee383173f
These BFI (Bad Frame Indications) substitute speech frames stolen
by FACCH/F or FACCH/H frames, so there can be no bit errors in
something that was not even transmitted over the air interface.
Change-Id: Icdb6209f75ead6581e3c18aeee0da9831aaa272a
According to 3GPP TS 45.003, clauses 4.2.5 and 4.3.5:
- one FACCH/F frame steals a single speech frame,
- one FACCH/H frame steals two speech frames.
A BFI (Bad Frame Indication) needs to be sent for each stolen
speech frame. This does not apply to CSD (data) channels though.
The BFI frames must have measurement data attached to them, and
due to their virtual nature (they do not actually come from the
air interface), the measurements must be crafted by trxcon.
Assigning a negative value to n_errors makes the code below the
'bfi' label craft fake measurement data. Otherwise, the actual
measurements belonging to the FACCH frame will be used.
Change-Id: Ia2f7c3cf7b1ef3737da6b1818cae2f001ee8768f
So far we used to store the sums of ToA and RSSI measurements in the
logical channel state, and after decoding of a block, we did calculate
the average. This approach works fine for xCCH and PDTCH, but when it
comes to block-diagonal interleaving (which is used on TCH/F and TCH/H
channels), the results are incorrect. The problem is that a burst on
TCH may carry 57 bits of one encoded frame and 57 bits of another.
Instead of calculating the sum of measurements on the fly, let's push
them into a circular buffer (the measurement history), and keep them
there even after decoding of a block. This would allow us to calculate
the average of N last measurements depending on the interleaving type.
A single circular buffer can hold up to 8 unique measurements, so the
recent measurements would basically override the oldest ones.
Change-Id: I211ee3314f0a284112a4deddc0e93028f4a27cef
Due to recent include dependency tree change in libosmocore, trxcon
fails now to build since it uncovered it's missing a header inclusion
for a symbol it is using:
osmocom-bb/src/host/trxcon/sched_trx.h:204:20: error: ‘GSM_MACBLOCK_LEN’ undeclared here (not in a function)
204 | uint8_t mr_cache[GSM_MACBLOCK_LEN];
| ^~~~~~~~~~~~~~~~
Change-Id: Ide22e525c106342b00171a8c08bb7265d19a651b
This feature may be useful for our TTCN-3 testing infrastructure.
By default it's disabled, and can be enabled using command line
arguments of the main binary:
./trxcon -g 127.0.0.1 ...
Change-Id: Iab4128fee5f18d816830fdca6c5ebebaf7451902
According to 3GPP TS 45.010, section 5.6.2, for packet-switched
channels the BTS shall monitor the delay of the Access Bursts
sent by the MS on PTCCH and respond with timing advance values
for all MS performing the procedure on that PDCH.
According to 3GPP TS 45.002, section 3.3.4.2, PTCCH (Packet Timing
advance control channel) is a packet dedicated channel, that is
used for continuous Timing Advance control (mentioned above).
There are two sub-types of that logical channel:
- PTCCH/U (Uplink): used to transmit random Access Bursts
to allow estimation of the Timing Advance for one MS in
packet transfer mode.
- PTCCH/D (Downlink): used by the network to transmit
Timing Advance updates for several MS.
As per 3GPP TS 45.003, section 5.2, the coding scheme used for
PTCCH/U is the same as for PRACH as specified in subclause 5.3,
while the coding scheme used for PTCCH/D is the same as for
CS-1 as specified in subclause 5.1.1.
The way we used to handle both PTCCH/U and PTCCH/D is absolutely
wrong - it has nothing to do with xCCH coding. Instead, we need
to use rx_pdtch_fn() for Downlink and tx_rach_fn() for Uplink.
Also, since we only have a shared RSL channel number for PDCH
(Osmocom-specific RSL_CHAN_OSMO_PDCH), there should be a way
to distinguish both PDTCH and PTCCH logical channels. Let's
introduce TRX_CH_LID_PTCCH for that.
Change-Id: I2d1e9b8a66f027047f8d7bdc3f82ff9d8ebcc25e
Oliver Smith
Vadim Yanitskiy
Pau Espin
Harald Welte
Vadim Yanitskiy