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
The gsm0503_pdtch_encode() returns negative number on error,
and the amount of encoded bits in case of success.
Change-Id: I7d75141142922909330c5e86be8734bb06cd57a4
During the handover the MS needs to release the existing dedicated
channel(s), establish the new one(s) as indicated by the network,
and then, depending on the synchronisation state, send one or more
HANDOVER ACCESS messages carried by Access Bursts.
In order to implement this, trxcon needs to be able to transmit
Access Bursts on any TDMA timeslot regardless of the logical
channel type and the associated handler, i.e. != TRXC_RACH.
The controlling side on L1CTL (layer23 or TTCN-3) needs to send
one or more L1CTL_RACH_REQ message(s) with properly populated
UL info header. Otherwise a regular RACH on TS0 is assumed.
Change-Id: Ia967820a536c99966ba2c60b63d2ea9edb093f46
Before this patch, prim_dequeue_sacch() used to ignore SACCH primitives
with odd length (e.g. 21, when sender forgot to push 2 octets of L1
SACCH header), so neither they were transmitted, nor rejected.
As a result, they would stay in the Tx queue until a dedicated
connection is released. The only way to notice such problem
was looking at the constantly growing talloc's report.
Instead of ignoring the primitives with odd length and keeping them
in the queue, let's pass them to a logical channel handler, so they
would be dequeued and rejected with a proper logging event.
Also, to simplify further debugging, let's print the final decision
of SACCH prioritization: whether it's a Measurement Report or not.
Change-Id: I3149fa518439470b397953306209eb859c83450a
According to 3GPP TS 05.02, section 6.4.1, CBCH replaces
SDCCH number 2 in both V (BCCH+CCCH+SDCCH/4+SACCH/4) and
VII (SDCCH/8+SACCH/8) logical channel combinations.
Unfortunately it is not clear whether we can use stolen UL slots
for RACH or not. For now, we should mark all of them as IDLE.
Somehow TRXC_SDCCH4_2 slots were left in the definition of
combination V (combined CCCH+BCCH). This is not critical,
but may be looking confusing. Let's fix this.
Change-Id: Id30f2fac3274de3edff4ae59f77d9c9cf8059155
The existing logic unconditionally wants to send a POWERON command
on TRXC whenever L1CTL_FBSB_REQ is received. That may cause some
problems when sending subsequent L1CTL_FBSB_REQ, e.g. due to signal loss.
Sending POWEROFF when transceiver is not powered on is normal though.
This can happen if trxcon is restarted while fake_trx was running.
The existing FSM state could unfortunately not been used, as it's a
mixture between the TRX connection state and the command/response state.
The current solution is just a work around. We definitely need to
introduce separate state machines for transceiver and its TRXC
interface.
Change-Id: I834e8897b95a2490811319697fc7cab6076db480
Both PRIM_IS_RACH() and PRIM_IS_EXT_RACH() macros to be used for
handover RACH detection in the follow up changes, thus we need
have them widely available. Let's also give them better names:
PRIM_IS_EXT_RACH -> PRIM_IS_RACH11
PRIM_IS_RACH -> PRIM_IS_RACH8
and introduce a new generic one for checking whether a given
primitive is RACH in general (either 8-bit or 11-bit) or not.
Change-Id: Ibc39c57fda000647be1829786f6423dcf3f435cd
It makes sense to do this first, before tuning to a different
ARFCN and changing the training sequence. Otherwise, if no
multi-frame configuration is found, trxcon would switch to
a different channel and then remain inactive there.
Change-Id: I274588ce3a9c49372b5da0629930afece46f799c
Having magic pre-calculated hex-masks gives one quite high chances
to shoot oneself in the foot, and decreases readability in general.
Let's do this pre-calculation during the compilation process, so
it's much easier to read, extend and spot potential bugs.
Change-Id: If945b3654e35c83fc0220fdd6d99c1c7a0503386
In I2fc61e1cdca4690a34e2861b9ee3b7c64ea64843 I introduced a regression.
TRXC_SDCCH4_CBCH should have TRX_CH_FLAG_AUTO, because it's a part of
GSM_PCHAN_CCCH_SDCCH4_CBCH multi-frame layout. If the controlling
side on the other end of the L1CTL link requests this particular
multi-frame layout, CBCH channel is expected to be active.
Change-Id: I3ed942106a03220417b5cb9176107af057120fbe
Let's avoid fancy alignment in the description of logical channels
for the benefits of having better readability, the ability to add
more comments and fields without making it look ugly.
Also, let's get rid of field 'chan' of 'trx_lchan_desc' structure
since it's not used anywhere, and not actually needed because the
position of each lchan description is defined by its TRXC_* type.
As a bonus, let's add a human readable description to each
lchan definition, so it can be printed in the VTY some day.
Change-Id: I2fc61e1cdca4690a34e2861b9ee3b7c64ea64843
PDCH channel support was introduced quite a while ago, but there
was no way to activate it via L1CTL so far. Let's fix this.
Change-Id: I3b66cab26108ab999a7fe969365ab57dc661399c
Wherever possible, use #defines from libosmogsm as opposed to magic
numbers. Using magic numbers in several places has the danger of
different programs/repositories having different views on what those
values mean.
Change-Id: I7ab4958801b3422973b67ff0452b90afa8a3f501
Related: OS#4027
Depends: libosmocore Change-Id I93e557358cf1c1b622f77f906959df7ca6d5cb12
OsmoBTS, BSC and TTCN3 used cbits == 0x18 for dynamic PDCH, while
trxcon wanted to use 0x18 for CBCH on SDCCH/4. Let's fix this and
bring everyone in agreement.
Related: OS#4027
Change-Id: Ia9a415628c659cbc2dd5dc65b875b7f935d6e211
According to the man page of recv(), the only difference of this
call from read() is the presence of flags. With a zero flags
argument, recv() is generally equivalent to read().
Change-Id: I6d43bbf8d52c5fbb8ee0592b7d1c1dfd2dd1548e
Since we only set both ARFCN and TDMA frame number of the DL info
header, other fields remain uninitialized. Let's memset() them.
Change-Id: Ib39c333f1724fefa5d8bd8a2315b77a5612f7fa9
This would allow to abstract both L1CTL and TRX interfaces
from each other in the upcoming refactoring.
Change-Id: I74a23c73b03bad822272b9cfe76c2501666912b7
According to 3GPP TS 05.03, section 5.3, two coding schemes are
specified for access bursts: one for regular 8-bit bursts,
another - for extended 11-bit packet access bursts.
According to 3GPP TS 05.02, section 5.2.7, there are two
additional training (synchronization) sequences for RACH
bursts: TS1 & TS2. By default, TS0 synch. sequence is used,
unless explicitly stated otherwise (see 3GPP TS 04.60).
According to 3GPP TS 04.60, section 11.2.5a, the EGPRS capability
can be indicated by the MS using an alternative training sequence
(i.e. TS1 or TS2) and the 11-bit RACH coding scheme.
Change-Id: I36fd20cd5502ce33c52f644ee4c22abb83350df8
Use static helper to prepare l1ctl_fbsb_conf - this simplifies
fbsb-related functions and make difference between timer callback and
regular response more obvious.
Change-Id: I43832d6a912a32ea5795ed0110981e0b714a7a61
Use static helpers to add l1ctl_info_dl to msgb - this simplifies
l1ctl_* routines and reduce code duplication.
Change-Id: I0b5b81f1fcd2984136e553a93735ea5456d2b3df
Instead of counting both RSSI and ToA measurements separately,
let's have a single counter in trx_lchan_state.meas struct.
Change-Id: I45454a3ac92b8cc85dd74092e4ab6eb350f20c9a
Both l1ctl_link_init() and trx_if_open() do accept 'tall_ctx' now,
so there is no need to expose the root context anymore. For
logging initialization, we can just pass a pointer.
Change-Id: I7a2231eb880a995d3296b94481a7799e6ff07489
The main changes are:
- return pointer to the allocated l1ctl_link or NULL,
- accept the talloc context as 'tall_ctx' argument.
Change-Id: I7fe1bc306494ac692c182dcfd2a2d9412929194b
The main changes are:
- return pointer to the allocated trx_instance or NULL,
- extend debug message with TRX address and base port,
- accept the talloc context as 'tall_ctx' argument,
- rename goto label 'error' to 'udp_error',
- rename argument 'port' to 'base_port'.
Change-Id: I39b24afee2f09d6a6c500cfc26ac45f206589c5c
Due to a mistake, average RSSI value of received bursts was not
converted to GSM RX level (range 0..63), so trxcon has been
sending incorrect values to the higher layers.
Let's fix this, and also prevent possible division by zero.
Change-Id: Id4659de899411ec1ba1718fdcb40aec562dbfd65
Vadim Yanitskiy
Pau Espin
Harald Welte
Eric Wild