Unlike xCCH, TCH/H channels are using block diagonal interleaving,
so every single burst carries 57 bits of one traffic frame, and 57
bits of another one. Moreover, unlike TCH/F where both traffic
and FACCH/F frames are interleaved over 8 bursts, a FACCH/H is
interleaved over 6 bursts, while a traffic frame is interleaved
over 4 bursts.
This is why a TCH/H burst transmission can't be initiated on
an arbitrary TDMA frame number. It shall be aligned as of
stated in GSM 05.02, clause 7, table 1.
This change introduces two basic functions:
- sched_tchh_block_map_fn - checks if a TCH/H block transmission
can be initiated / finished on a given frame number
and a given channel type;
- sched_tchh_block_dl_first_fn - calculates TDMA frame number of
the first burst using given frame number of the last burst;
and some auxiliary wrappers to simplify the usage of
sched_tchh_block_map_fn().
Change-Id: Iaf4cb33f1b79df23f8a90c8b14ebe0cd9907fbb9
This field of the logical channel state structure was not used at
all as there is nothing related to A-bis / RSL in trxcon itself.
Change-Id: Iec1abf777a74cf57deadafa95e2337cba5d02842
Instead of passing the information about a logical channel, it
makes sense to pass the pointer to its state where everything
is stored. This approach would allow to avoid adding more
arguments every time, e.g. in case of AMR.
Change-Id: I91fe86fef43aac68776a58c9acc37ef2a9ee8042
Initially it was assumed that FACCH prioritization should be done
in the same way for both TCH/F and TCH/H. Moreover, it was not
possible to confirm this, because TCH/H was (and still) not
implemented yet. But according to the specs:
- unlike FACCH/F, FACCH/H transmissions shall be aligned
within a multiframe, i.e. can only be initiated on
particular frame numbers (see GSM 05.02, clause 7);
- unlike FACCH/F, a FACCH/H frame steals two TCH/F frames;
so the TCH/H (including FACCH/H) primitives should be handled
separately from the TCH/F (including FACCH/F) primitives.
Change-Id: I9b59f60e1cbac8fb8fd557b6c67b5e376c0a6bbb
The previous primitive dequeuing logic (especially for TCH/F
channels) was a bit complicated, and it could not be possible
to reuse the existing code parts in the upcoming implementation
of both TCH/H and FACCH/H channels without changing anything.
In particular, this change introduces two internal functions:
- prim_dequeue_one(), which merely dequeues a primitive
of a given channel type (e.g. TRXC_SDCCH4_0);
- prim_dequeue_tch(), which dequeues either a FACCH,
or a speech TCH primitive of a given channel
type (Lm or Bm).
So the logic of the TCH/F prim dequeuing function has become
cleaner, and the upcoming TCH/H prim dequeuing function, where
FACCH/H prioritization is more complex than FACCH/F, will
reuse the introduced functions.
Change-Id: Ib82ad2480ab1bc6b1df9576eb2bf5acbd398bf66
The main problem here is that the existing implementatin missing the L1
header in this message. A SACCH message doesn't have a 23byte LAPDm
message, but only a 21 byte LAPDm message prefixed by a 2-byte Layer1
header. So on the receiver in the BTS, right now the first two bytes of
the UL SACCH frame are misinterpreted as L1 header.
This it what causes RLL ERROR INDICATION on the Abis side, which is why
our BTS_Tests fail.
Change-Id: Id7776bf3604d0e8a32e04547e01b8bd377903272
Related: OS#3170
According to TS 144.006, section 5.2, the first octet containing
fill bits shall be set to the binary value "00101011" == 0x2b.
Change-Id: I8f0304bf84613a2dc07cb78aff0cb8bb4c5adf6c
If at the moment of transmission there are no frames in TX buffer,
then either a dummy LAPDm frame (0x01, 0x03, 0x01, 0x2b ...) or a
silence frame (depending on a codec in use) shall be transmitted.
This is required for proper measurements on the BTS side.
Change-Id: Ie590990f2274ea476678f6b2079f90eeadab6501
Initially it was expected that a TCH transmit queue could contain
TCH and FACCH primitives only. But there are also SACCH primitives,
which are also being stored there.
So, let's drop the assertations from the sched_prim_dequeue_tch(),
and return NULL if nothing was found.
Change-Id: Iae37057d35883c09a76f0612e52c2d14d9ff91cb
Previously we used to compare two consecutive first primitives,
taken from a transmit queue. This approach may cause some delay,
which is critical for FACCH e.g. in case of handover.
Let's walk through a whole transmit queue to find a pair of
both FACCH frames, and only then decide what to do.
Change-Id: I925cca77bfaa255dd095bc882c901d41c9bc4633
Previously, each lchan handler used to obtain and delete primitives
from a timeslot's tranmit queue itself. This approach entails many
potential problems and bugs:
- The lchan handlers shall not do that by definition, they
should encode and decode frames according to GSM 05.03.
- In some cases (e.g. TCH), a single transmit queue may contain
primitives of different types (e.g. TCH, FACCH and SACCH). At
the same time, the lchan handlers don't care and don't even
know about each other. So, this could cause an unexpected
behaviour in some cases.
This change separates all primitive management routines,
providing a new API for obtaining and dropping them.
"Write programs that do one thing and do it well."
Change-Id: I29503ece51903784bc53541015285234471c8d15
It's good to write, keep and make the source code as much modular
as possible. So, Tte primitive management code was separated to
the 'sched_prim.c' and going to be extended in the near future.
Change-Id: Ifec8c9e4f2c95c72b00772688bcb5dc9c11d6de7
Vadim Yanitskiy
Harald Welte