This is the first step towards the goal of moving the scheduler
into a separate library.
Change-Id: Ifa6137c239c215a3d323213ee74d34b419622be4
Related: OS#5599, OS#3761
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
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
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
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
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 GSM TS 05.02, section 3.3.5, Cell Broadcast Channel
(CBCH) is a downlink only channel, which is used to carry the
short message service cell broadcast (SMSCB). CBCH is optional,
and uses the same physical channel as SDCCH. More precisely,
CBCH replaces sub-slot number 2 of SDCCH channels when enabled.
This change introduces the CBCH enabled multi-frame layouts,
and two separate logical channel types:
- GSM_PCHAN_CCCH_SDCCH4_CBCH (lchan TRXC_SDCCH4_CBCH),
- GSM_PCHAN_SDCCH8_SACCH8C_CBCH (lchan TRXC_SDCCH8_CBCH).
Both logical channels are separately identified using
the following Osmocom specific cbits:
- TRXC_SDCCH4_CBCH - 0x18 (0b11000),
- TRXC_SDCCH8_CBCH - 0x19 (0b11001).
The reason of this separation is that we somehow need to
distinguish between CBCH on C0/TS0, and CBCH on CX/TS0.
Unlike TRXC_SDCCH8_CBCH, TRXC_SDCCH4_CBCH is enabled
automatically (TRX_CH_FLAG_AUTO), so CBCH messages
can be decoded on C0 while being in idle mode.
Change-Id: Iad9905fc3a8a012ff1ada26ff95af384816f9873
According to GSM TS 08.58, chapter 9.3.1, channel number 0x08
describes sub-slot number 0 of SDCCH/8+ACCH. This is definitely
wrong. In OsmoBTS we use an Osmocom specific extension for packet
switched channels - 0xc0, so let's use it here too.
Change-Id: I11925408d6e63baf1eac880839ecd717843fba6a
This new flag is intended to indicate that continuous burst
transmission is assumed on particular logical channel. In other
words, if a logical channel has this flag, but there is nothing
to transmit in a TX buffer, then either a dummy LAPDm frame or
a silence frame shall be sent.
Change-Id: I25fcf9eeb787ffe5378d92532439e67d7d42fa65
There's no need to express ToA value as a float. Let's turn it into
an int16_t with 1/256 symbol period accuracy throughout the code to
avoid both float arithmetic as well as loosing any precision.
Inspired by Idce4178e0b1f7e940ebc22b3e2f340fcd544d4ec.
Change-Id: I99c0f38db08a530d5846c474aba352aa0b68fe86
This change implements basic TCH/F lchan handlers for both data
reception and transmission. Only FACCH (signaling), FR and EFR
payloads are supported at the moment.
Change-Id: If6b0eaede2b484484d2a824e7219ff04483266a1
It's better to pass a trx_lchan_state instance directly from
caller to lchan handler instead of passing trx_lchan_type. This
way a handler wouldn't need to find lchan itself.
Change-Id: I47a40542b03ab31da12b0abb1c263c83662ff018
Vadim Yanitskiy
Vadim Yanitskiy
Harald Welte