This patch adds the [de]interleaving for CSD (circuit switched data),
nominally for TCH/F 9.6, but the same is also used for TCH/F 4.8,
TCH/H 4.8, TCH/F 2.4 and TCH/F 14.4.
Related: OS#4396, OS#1572
Change-Id: I6b16c2d0d7febf3883da662b2c7fec543335de12
Currently there's a big mess where include dir osmocom/gprs/ is used by
both libosmogsm and libosmogb.
Most of the header files under osmocom/gprs/ are actually all the
headers of libosmogb (there's no osmocom/gb/ dir). But a couple files
are actually RLC/MAC (TS 44.060) related are are also stored in there.
Those files have no relation/use in Gb, and are actually interused with
GSM (eg System Information 13 Rest Octets).
Hence, it makes sense to have the RLC/MAC related parts inside
osmocom/gsm/ as they should be in libosmogsm (and they actually are,
see gprs_rlc.h function implemented in src/gsm/gsm48_rest_octets.c).
The fact that some libosmogsm headers were placed in osmocom/gprs
instead of osmocom/gsm already created some issues, like
libosmocore.spec.in putting "%_includedir/%name/osmocom/gprs/" under
libosmogb, which is wrong.
As a first step to fix the mess, we move the 2 RLC/MAC headers currently
under osmocom/gprs/{gprs_rlc,protocol/gsm_04_60}.h under a single header
gsm/protocol/gsm_44_060.h
The two old headers are left existing for backward compatibility and now
simply include the new libosmogsm header, plus a warning asking users to
switch to the new header so we can eventually get rid of them.
This means libosmogb depends on libosmogsm, which is fine and was
already the case beforehand (libosmogb using functions like
gsm48_encode_ra() and linking against it in src/gb/Makefile.am).
Change-Id: I70cc21bf25a7081070738abacb409ed19094c3b2
config.h is created in $(top_buildir)/config.h.
Let's make sure all CPPFLAGS add correct -Ipath includes,
and that all code includes the correct file.
Change-Id: Ie9ea38bb009bc715b01cde4d66d181f7bec2e7bd
This way we have all libosmocore.so in an own subdir instead of having
lots of files in the parent dir, which also contains subdirs to other
libraries.
This also matches the schema under include/osmocom/.
Change-Id: I6c76fafebdd5e961aed88bbecd2c16bc69d580e2
These functions can be re-used for parsing in-band data from DTX
specific frames like SID_FIRST, SID_UPDATE, SID_ONSET, etc.
Change-Id: I0106de7a7f87517006e323299b2dc08457d1c6cf
Related: OS#5570
The new functions accept an additional mode_id poiner, which is
currently set for the following frames: AFS_ONSET, AHS_ONSET,
AHS_SID_FIRST_P2 with N * 16 - M bit pattern.
Also, the new API accepts soft-bits instead of hard-bits.
Converting bits from soft to hard is now performed internally.
Change-Id: Ibcac395f800bb64150c97fcdaca3523ecfc5fcee
Related: OS#5570
Parsing of CMI/CMC/CMR from AMR's special DTX frames is currently
not implemented. It's better to keep the old stored value rather
than resetting it to 0 every time we receive such a frame.
Add TODO comments for each DTX frame type.
Change-Id: Ic4edbb8ab873fe0bdd69a8710803628bc4f447d0
Related: OS#5570
As was demonstrated in [1], there is a TCH/AHS specific problem in
libosmocoding causing unexpected BER ~50% in decoded AHS_SID_UPDATE
frames. The reason is that A[H]S_SID_UPDATE employs quite tricky
interleaving algorithm, which is different from the algorithm used
by normal TCH/AHS speech frames or A[F]S_SID_UPDATE frames.
An AHS_SID_UPDATE frame consists of two halves (228 bits each):
+---------+--------------------|---------+--------------------+
| in-band | SID marker | in-band | coded data |
+---------+--------------------|---------+--------------------+
| 16 bits | 212 bits | 16 bits | 212 bits |
The first half contains coded in-band signalling data (16 bits) and
the identification marker (212 bits), which allows to detect that
it's an AHS_SID_UPDATE. This half is carried by even bits of the
first two bursts and odd bits of the last two bursts.
The other half also contains the in-band data (16 bits), while the
remaining 212 bits contain encoded SID_UPDATE (212 bits). This
half is carried by even bits of the last two bursts and odd bits
of the first two bursts.
Current implementation does not use odd bits of the first two
bursts at all, so buffer cB[] in gsm0503_tch_ahs_decode_dtx()
contains only 114 out of 228 bits.
This patch changes the logic, so that gsm0503_tch_ahs_decode_dtx()
would not split AHS_SID_UPDATE onto two frames anymore like its
TCH/AFS equivalent does, but attempt to deinterleave the second
half and attempt to decode the payload immediately.
Change-Id: I8686d895e96fa0e606c1898b6574cc80a8f46983
Related: [1] I434157e2091a306c039123cea08d84bd8533c937
Related: SYS#5853
Both gsm0503_tch_a[fh]s_decode_dtx() functions accept an optional
'dtx' pointer, which is used to indicate type of a received AMR
block to the caller in DTX mode of operation. If not NULL, it's
expected to be updated by gsm0503_detect_a[fh]s_dtx_frame() every
time one of the mentioned functions is called.
However, in case of FACCH both functions return early, so the value
of dtx remains unchanged and thus FACCH frames may be misinterpreted
as AMR's special DTX frames. This is rather critical during the DTX
silence periods, when all special DTX frames (e.g. SID_UPDATE) are
being treated as SUB frames. Each unsuccessful FACCH decoding
attempt will 'poison' SUB measurements, causing unexpected RxQual-
SUB values in the Uplink measurement reports.
Fix this by resetting *dtx to AMR_OTHER in the FACCH specific path.
Change-Id: I2e6f4b748c6445725211e264ab5f3f5a2712087a
Related: SYS#5853
There are two similar values in enum gsm0503_amr_dtx_frames:
* AFS_SID_UPDATE - precursor of SID UPDATE,
* AFS_SID_UPDATE_CN - the actual SID UPDATE.
The former is internally used by libosmocoding to mark the current
frame as a precursor of the actual SID UPDATE frame - the later.
+---+---+---+---+---+---+---+---+
| _ | _ | _ | _ | a | b | c | d | AFS_SID_UPDATE
+---+---+---+---+---+---+---+---+
| a | b | c | d | _ | _ | _ | _ | AFS_SID_UPDATE_CN
+---+---+---+---+---+---+---+---+
This is required because function gsm0503_tch_afs_decode_dtx() is
invoked by TDMA scheduler on every 4th received burst, while the
burst buffer is 8 bursts wide.
Currently, whenever gsm0503_detect_afs_dtx_frame() detects an
AFS_SID_UPDATE frame, we still attempt to decode it as a speech
or data below in gsm0503_tch_afs_decode_dtx(). This is indeed
a bug, which results in unexpected BER values:
* expected BER 0/212,
* actual BER 252/448.
We should return immediately once we have detected an AFS_SID_UPDATE.
This patch fixes unexpected BER-SUB values during DTXu silence periods.
Change-Id: I813081a4c0865958eee2496fe251ae17235ac842
Related: SYS#5853
"""
/libosmocore/src/coding/gsm0503_coding.c: In function 'osmo_conv_decode_ber_punctured':
/libosmocore/src/coding/gsm0503_coding.c:563:31: error: 'coded_len' may be used uninitialized [-Werror=maybe-uninitialized]
563 | *n_bits_total = coded_len;
| ~~~~~~~~~~~~~~^~~~~~~~~~~
/libosmocore/src/coding/gsm0503_coding.c:541:21: note: 'coded_len' was declared here
541 | int res, i, coded_len;
| ^~~~~~~~~
"""
This error is really a false positive. However, it is true that the code
used to be a bit more complex than required, since the 2 later conditions
could be inside the first one.
Let's simply do early termination to simplify the function, and get rid
of the gcc warning.
Change-Id: I31ebf0c4be61daf6395d9a9fac05c7fdceb8bcb9
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: I5050285e75cf120407a1d883e99b3c4bcae8ffd7
The encoder function gsm0503_tch_ahs_encode uses gsm0503_afs_ic_ubit
when encoding the CMR or FT (depends on the frame number). This is not
correct. It should use gsm0503_ahs_ic_ubit instead.
Change-Id: Id250b2102ac79ff222bd3ad9d1abc4b60abdd12b
Related: SYS#5549
The value string array that explain the type of the AMR DTX / SID
frames is incomplete, lets add the missing strings.
Change-Id: If9e80b4bd8bdc31323c7c276155b2538e20a99be
Related: OS#2978
gsm0503_coding contains AMR decoder functions for HR and FR. Those can
only decode AMR payload frames but not amr DTX frames. Lets add
functionality to detect DTX frames. Also lets add decoding for SID_UPDATE
frames as well as error checking for the SID frame recognition patterns.
Related: OS#2978
Change-Id: I2bbdb39ea20461ca08b2e6f1a33532cb55cd5195
osmo-gsm-tester raised an ASan warning in osmo-bts-trx during execution
of a test with EGPRS enabled and a modem connecting to it (see OS#4483
for full trace):
==12388==ERROR: AddressSanitizer: global-buffer-overflow on address 0x7fa20b9ab8d0 at pc 0x7fa20b982894 bp 0x7ffdfea8b9c0 sp 0x7ffdfea8b9b8
READ of size 1 at 0x7fa20b9ab8d0 thread T0
#0 0x7fa20b982893 in gsm0503_mcs1_dl_interleave /home/osmocom-build/jenkins/workspace/osmo-gsm-tester_build-osmo-bts/libosmocore/src/coding/gsm0503_interleaving.c:165
Function gsm0503_mcs1_dl_interleave() was being passed the 6-bit USF
encoding while clrearly expecting a 12 element array. TS 05.03 5.1.5.1.2
"USF precoding" also clearly states that 12bit encoding is to be used
for MCS1-4.
Fixes: OS#4483
Change-Id: I94db14de770070b17894a9071aa14391d26e776c
According to 3GPP TS 44.004, figure 7.4a.b, the format of 11-bit
RACH uplink / Uplink access burst block is as defined follows:
<---------------------------------------------------
8 7 6 5 4 3 2 1
+--------------------------------------------------+
| 11 bit RACH uplink / Uplink access burst block | OCT1
+--------------------------------------------------+
| | OCT2
+-------------------+
As was (correctly) assumed in [1], the bit ordering in 11-bit RACH
coding functions is wrong. The problem is that neither of generic
functions from bit16gen.h can be used to load / store the RA11
value (regardless of the endianness), because they assume that
the payload is 16 bit long.
With this patch applied, RA11 values from [1] look correct:
< EGPRS Packet channel request message content > ::=
< Signalling : 110011 < RandomBits : 00111 > > |
< Signalling : 110011 < RandomBits : 00110 > > |
< Signalling : 110011 < RandomBits : 01111 > > |
< Signalling : 110011 < RandomBits : 01100 > > |
< Signalling : 110011 < RandomBits : 00111 > > |
< Signalling : 110011 < RandomBits : 10110 > > ;
[1] Id80e471d252b9416217b56f4c8c0a8f5f1289fee
Change-Id: I43d30611dd69f77f2b3b46f4b56056a8891d3c24
Related: OS#1548
AMR not only specifies a 6 bit CRC for regular voice information. It also
specifies a 14 bit CRC to protect the comfort noise updates contained in
the SID_UPDATE frames.
Change-Id: I5cfd8ca806aba8d42cb9787f69605cea7de6e900
Related: OS#2978
As a result whitespace ended up in some variables and then command
"expr" was not happy about it.
It was spotted because src/coding/Makefile.am had some whitespacing.
Since it's the only one, let's drop the whitespace there too to have
similar line in all Makefile.am files.
Change-Id: I33afef5e4ef9eb36de81274533f46598ba9a0edb
Previsouly there were a lot of valid code paths which returned from the function
before setting bit counters which led to bogus BER output in osmo-bts-trx logs
when those code paths were hit.
Change-Id: I4722cae3794ccbb12001113c991d9cf345a52a96
Previously we didn't take into account puncturing and BER was always around
30% for GPRS/EDGE bursts because of they use puncturing coding unlike
"classical" GSM bursts.
Change-Id: I9da22e7051522d06d923fcec3b63cbed8db93910
For all other decode operations we report the BER, but not for the
RACH. This results in osmo-bts-trx not being able to report BER
to the higher layers, which is possible on other BTS backends.
Let's close this gap by introducing gsm0503_rach_ext_decode_ber()
and gsm0503_rach_decode_ber() with the usual n_errors / n_bits_total
arguments.
Change-Id: I2b1926a37bde860dcfeb0d613eb55a71271928c5
Since commit e094157e12, TCH frame
length definitions were added to libosmocodec.
No need to define them again.
Change-Id: Id8c6132534e36ea1e368432bb259fd4f3a531f90
As a leftover from code move from OsmoBTS we have eB adjustement outside
of eB check in gsm0503_tch_burst_map() which is rightfully noted by
Coverity. Let's fix this by moving the adjustement under the
corresponding if.
Change-Id: I385cd6ffea4d13ef911910fc87c92b73809888a2
Fixes: CID57691
Let's fix some erroneous/accidential references to wrong license,
update copyright information where applicable and introduce a
SPDX-License-Identifier to all files.
Change-Id: I39af26c6aaaf5c926966391f6565fc5936be21af
The EFR coding contains some repeated bits. In case there are
transmission errors, some bits may of course get corrupted. It looks
like there's an improvement can be made by taking a majority vote on
those "repetition bits", i.e. if 2 out of 3 bits are the same, then use
that instead of expecting to match all 3 bits.
See 3GPP TS 45.003 Section 3.1.1.3 for reference.
Change-Id: I2a28a4d7fb82aed4d39fe8efeea702effdba3858
There's an error in tch_efr_unreorder() function in gsm0503_coding.c
that results in increased RBER. One of the indices used by repetition
bit recombining in this function doesn't match 3GPP TS 45.003 section
3.1.1.3, specifically "w(k) = s(223) for k = 231 and 232".
This bug resulted in RBER even under ideal conditions, with no
fading or AWGN present.
Change-Id: I153da7bbc1bb3e01ed31eb5a7417e90841cfcde3
Despite the libosmocoding.map is preset since the library release,
one was not used in a proper way. The LTLDFLAGS were missing, so
let's add them.
Change-Id: Idf677825ff642d50bea43c7f970810783e864fdd
Considering the various styles and implications found in the sources, edit
scores of files to follow the same API doc guidelines around the doxygen
grouping and the \file tag.
Many files now show a short description in the generated API doc that was so
far only available as C comment.
The guidelines and reasoning behind it is documented at
https://osmocom.org/projects/cellular-infrastructure/wiki/Guidelines_for_API_documentation
In some instances, remove file comments and add to the corresponding group
instead, to be shared among several files (e.g. bitvec).
Change-Id: Ifa70e77e90462b5eb2b0457c70fd25275910c72b
Especially for short descriptions, it is annoying to have to type \brief for
every single API doc.
Drop all \brief and enable the AUTOBRIEF feature of doxygen, which always takes
the first sentence of an API doc as the brief description.
Change-Id: I11a8a821b065a128108641a2a63fb5a2b1916e87
It's universally useful so it make sense to have it in the shared core:
* move macro from libosmocoding to libosmocore
* add OSMO_ prefix
* add doxygen docs
Change-Id: I5386ba3e1f1cc153ba96c29dc71c9075a052aa02
The table describing the various MCS convolutional codes are constant
data and should be marked as such.
Change-Id: I4918521ee4572a67cbee5f9b49257fc5bfcde511
Harald Welte
Pau Espin
Vadim Yanitskiy
Oliver Smith
Philipp Maier
Vadim Yanitskiy
Neels Hofmeyr