Adds support to find the puncturing scheme for retransmission
with MCS change, retransmission with no MCS change, transmission
case. Puncturing scheme selection for retransmission case with
MCS change is aligned with TS 44.060 9.3.2.1. Puncturing scheme
selection for retransmission without MCS change, fresh transmission
is aligned with TS 44.060 10.4.8a.3.1, 10.4.8a.2.1, 10.4.8a.1.1
This patch is for fixing encoding of padding bits according to the
3gpp spec 44.060 section 11, wherein it shall always start with 0
bit followed with spare padding bits.
During introduction of basic EGPRS feature new hex dump messages
from a different working network log were used in Unit test. These
exposed the issue of incorrect handling of padding bits encoding
in osmo-pcu.
Corrections in the existing test vector of rlcmac is also updated.
In testsuite tbf appropriate corrections for the Tbftest.err is
also done.
Currently single BSN blocks of size 68 (a single unit from MCS-8)
are put into a MCS-6 block with padding according to TS 44.060
Annex J. Unfortunately, these packets are ignored by the E71. This
might be related to the currently incorrect usage of the puncturing
schemes and the RSB bit (the puncturing schemes are not updated and
the RBS flag is never set).
Avoid downgrading from MCS-8 to MCS-6 if there is no second block
available. Send the block twice instead.
Sponsored-by: On-Waves ehf
Currently only one BSN block is encoded in each RLC data message,
even if MSC7-9 are used, which transport two independant (except for a
max BSN delta of 512) BSN blocks. In that case, the same block is
just put twice into the same message.
The current create_dl_acked_block(fn, ts) method handles
block selection (resend, new BSN, dummy block, ...) and restart
handling in one method and is too complex to extend it accordingly.
Therefore this commit move the block selection/creation handling into
a new method (take_next_bsn) which delivers the next BSN along with a
hint, whether it may be combined with another block. In that case,
the function can be called a second time (this time with a valid
previous BSN, that's the one returned by the first call) to get the
second BSN. The real block generation method
create_dl_acked_block(fn, ts, index, index2) is then called with both
BSNs as indices (the second must be -1, if there is only one BSN).
Note that every BSN returned by take_next_bsn should be passed to
create_dl_acked_block to avoid state inconsistencies.
Sponsored-by: On-Waves ehf
Currently the method is hard-coded to support a single BSN only.
MCS-7 to MCS-9 encode 2 data blocks into a single RLC data message.
This commit refactors create_dl_acked_block to process any number
of blocks internally.
Note that this does not extend the parameter list accordingly and
just duplicates the BSN if these MCS are being used.
Sponsored-by: On-Waves ehf
Currently the state on the TBF is set to ASSIGN when it is created
and in general changed to FLOW when it is acknowledged by the MS. The
moment when the assignment is really transmitted to the MS (which can
take some time) is not reflected by the state. A TBF can considered
to be valid, when the assignment is received by the MS.
Add the state WAIT_ASSIGN that is entered when the assigment has been
send to the MS (more precisely: when the corresponding RTS has been
processed or the message has been sent to the BTS).
The TBF, its PDCH(s), and its TFI can be assumed to be valid, when the
TBF has a state of WAIT_ASSIGN or higher (assuming that the TBF
starting time has not been set, which is currently only done for SBA,
which are not associated with a TBF).
Note that due to queuing in the BTS there can still be a invalid
time period for immediate assignments, when the request is lingering
in the AGCH or PCH queues.
Sponsored-by: On-Waves ehf
The EGPRS support will need more information to encode the IMMEDIATE
ASSIGMENT. Instead of adding more parameters pass a pointer to the
TBF unless an SBA shall be done (indicated by tbf == NULL). All
values that can be derived from the TBF and are not needed for an SBA
are removed from the parameter list.
Return a negative value on error.
Sponsored-by: On-Waves ehf
Currently the old TFI is always used as ID when a
PACKET DOWNLINK ASSIGNMENT is generated. This fails
if the old TBF has not been fully assigned yet. The
MS will then ignore the PDA.
This commit changes write_packet_downlink_assignment to accept
an additional parameter old_tfi_is_valid and uses the new TBF's
TLLI instead of the olf TFI if that parameter is set to false.
Sponsored-by: On-Waves ehf
Currently the checks for and the actual polling is done in several
places by copy & paste of several lines of code. This hinders changes
of they polling is handled internally and also is likely source of
programming mistakes.
Separate this into a check_polling function, that checks whether
polling is possible and returns the FN and the RRBP to be used in
that case. Otherwise the cause is logged (LOGL_DEBUG) and a negative
error value is returned. There are no other side effect beside the
logging.
If the call is successful, the set_polling method can be used to
actually register the polling.
Extend the encoder functions' parameters lists by an rrbp parameter.
Sponsored-by: On-Waves ehf
Currently tbf->control_ts is used to look up an incoming poll
response. Since that may eventually change, poll timeouts could
theoretically happen in that case.
Store the real poll TS in tbf->poll_ts at all places where
tbf->poll_fn is set. Do not use tbf->control_ts to look up
outstanding polls.
Sponsored-by: On-Waves ehf
Currently existing TBF can be reused after an MS has sent a RACH
request. Since the MS can be or most probably is in packet idle mode
in that case, the TBF are no longer usable even if they share the
PDCHs and the control TS with the new one.
There are occasional freezes where the MS does no longer react to
messages sent on the PACCH.
This change aborts all pending TBFs if a new TBF is or has been
established via RACH.
Sponsored-by: On-Waves ehf
Currently the is a release() function which takes care of
statistics and shutdown of properly finished TBFs, but which
cannot be used for aborted TBFs.
This commit add an abort() method which handles unacked RLC blocks
as lost and doesn't start a release timer. This method will be
invoked by tbf_free() for downlink TBF.
Sponsored-by: On-Waves ehf
Make use of variables, log them to LOGL_DEBUG, and reduce code
duplication.
This should help to narrow down the cause why snd_dl_ass are not
answered by the MS sometimes.
Sponsored-by: On-Waves ehf
Currently the values in the BSSGP RA Cap IE are eventually use
overwrite the 'good' values obtained from the MS earlier.
Use the 'good' values when the are present, which is assumed if
at least one of ms->ms_class() or ms->egprs_ms_class() is set.
Sponsored-by: On-Waves ehf
Currently the window size is fixed to 64 even for EGPRS.
Support dynamic window sizes depending on the number of PDCH. The
WS can be set to b + f * N_PDCH. If the result is not valid according
to TS 44.060, Table 9.1.9.2.1, the value will be corrected to use the
next lower valid value (or 64).
The following VTY commands are added (config-pcu node):
window-size <0-1024> set base (b) value and leave f unchanged
window-size <0-1024> <0-256> set base (b) and factor (f)
Sponsored-by: On-Waves ehf
Currently the plain 'egprs' command enables EGPRS but doesn't prevent
phones from being served in GPRS mode if they do not support EGPRS.
This involves complex frame allocation implementations in dynamic
mode, especially if 8PSK is being used. This is due to the inability
of non-EGPRS phone to decode 8PSK USF and ES/P altogether. Since
polling has a higher priority than USF, collisions will have to be
prevented by the PCU by never using an GPRS USF if it refers to a FN
that is already being used for polling.
This commit just disables mixed usage by ignoring GPRS-only request
if EGPRS is enabled.
The following VTY command (config-pcu node) is changed:
egprs -> egprs only
Sponsored-by: On-Waves ehf
The bitvec RBB is always valid, even when FINAL_ACK_INDICATION is
set. This is done by the ack/nack decoder function which fake a
bitmap starting with V(A) up to V(S)-1 in that case (see
Decoding::handle_final_ack).
Call gprs_rlcmac_dl_tbf::update_window unconditionally and only use
is_final for logging and TBF state changes in
gprs_rlcmac_dl_tbf::rcvd_dl_ack.
Sponsored-by: On-Waves ehf
Currently TBF related tasks (status changes, counter updates,
LLC dummy command insertion) as well as
RLC data block generation are done within create_new_bsn.
The data block creation part has already been copied to
the stateless Encoding::rlc_data_to_dl_append function.
This commit changes create_new_bsn to use the encoder function and
just care about the TBF related stuff.
Since the rlc_data_to_dl_append function has been validated against
the test cases being described in annex B of TS 44.060, this
commit fixes an encoder bug which leads to broken LLC frames in
a special case (see example B.2, the main header's E bit was
erroneously set to 1 in that case). When this happens, the LLC frame
will get discarded after reassembly, so that TCP will have to
retransmit the lost packet.
Sponsored-by: On-Waves ehf
This commit removes the use of struct rlc_dl_header from
gprs_rlcmac_dl_tbf::create_dl_acked_block and
gprs_rlcmac_dl_tbf::create_new_bsn. Instead of patching the
data area directly, the RLC block encoding functions are used.
Note that the data unit encoding is still hard-coded to GPRS in
create_new_bsn, so using MCS 1-4 (albeit being supported by the
encoder) will not work yet.
Sponsored-by: On-Waves ehf
Currently GPRS is always used for downlink, which violates TS 44.060
(concurrent TBF must have the same mode).
Enable EGPRS mode for downlink if the EGPRS MS class is != 0 and
EGRPS has been enabled.
Note that EGPRS Ack/Nack handling is not yet implemented, so enabling
EGPRS will not work still. But we will now get EGPRS DL ACK/NACK
messages now from the MS.
Sponsored-by: On-Waves ehf
Currently the TBF and MS object use a plain integer value
(current_cs) to manage the coding scheme. This makes it difficult to
support the MCS schemes. GprsCodingScheme supports a partial ordering
of these values (CS and MCS) and provides safe increment and
decrement methods.
Use the GprsCodingScheme type instead of integer for cs fields and
variables. Add a 'mode' to GprsMs which can be set to either GPRS,
EGPRS, or EGPRS_GMSK which also set the initial values of
current_cs_ul/dl. Select the mode based on max_mcs_ul and max_mcs_dl.
Sponsored-by: On-Waves ehf
Currently GPRS is handled by the old code path while EGPRS already
uses the unified functions. The rcv_block_egprs is basically not
specific to EGPRS and just needs minor modifications to handle GPRS.
This commit turns gprs_rlcmac_pdch::rcv_block_egprs into a unified
rcv_data_block method and uses it for GPRS, too.
Note that the logging messages of the new parser are different.
Sponsored-by: On-Waves ehf
Currently gprs_rlcmac_tbf::extract_tlli takes care of decoding and
the TBF update. These are really different things and doing the
decoding in extract_tlli makes EGPRS support more complex.
This commit moves the TBF state related part into a new method
gprs_rlcmac_tbf::set_tlli_from_ul.
Sponsored-by: On-Waves ehf
Currently the block size is mapped by a switch statement to strip
extra bits that are not used for RLC blocks. That information is
already available via the GprsCodingScheme class.
This commit moves the CS/MCS detection to the rcv_block message and
passes the cs object via rcv_block_gprs, where the length gets
adjusted, to gprs_rlcmac_pdch::rcv_data_block_acknowledged. There the
switch statement is removed.
Note that the TbfTest.err changes due to an additional log message.
Sponsored-by: On-Waves ehf
The leak rate sent to the SGSN does not reflect the current CS level,
lost frames, and control message overhead. So the SGSN cannot do
proper queue control under non-optimal conditions.
This commit computes the leak rate for the last flow control interval
by computing the maximum theoretical leak rate and basically
substracting control blocks, nacked blocks, and reduced block sizes
due to CS downgrade. By using this approach, the value will by more
stable on low load, where the value will tend to be near the value
derived from the configuration. On full load the transmitted value is
completely derived from the measurements.
Note that the MS default values are no adapted to the adapted BVC
leak rate, since a single MS which has a lower link quality would
otherwise be reducing the rate of another MS with good radio
conditions, which would not make much sense if they did not share any
PDCH.
Sponsored-by: On-Waves ehf
Currently an existing DL TBF can get lost in the process of
establishing an UL TBF via RACH. This can lead to stalled connections
until the network sends more LLC frames.
This commit adds a check for a non-empty LLC queue after the UL TBF
has been established to rcv_control_ack (GPRS_RLCMAC_UL_ASS_WAIT_ACK
path) to eventually establish a new DL TBF on the UL TBF's PACCH.
Sponsored-by: On-Waves ehf
Currently an existing DL TBF is freed immediately, when a resource
request is received. This makes sense since the MS might have dropped
it when switching to the PDCH signaled via the AGCH for the SBA. But
if the TBF still is assumed to exist on the MS side, there might be
TFI collisions if the old TBF object is not kept to block its TFI
for some time.
This commit changes rcv_resource_request to call release() instead of
tbf_free() on the DL TBF object (if it exists).
Sponsored-by: On-Waves ehf
Currently reuse_tbf (partly) resets the old DL TBF and uses its PACCH
to establish a new DL TBF. The method can not be used with UL TBFs.
This commit replaces the reuse_tbf method into a
gprs_rlcmac_dl_tbf:release method which triggers the TBF's timer
based deletion (so that the TFI is still reserved for some time) and
a gprs_rlcmac_tbf::establish_dl_tbf_on_pacch which can establish DL
TBFs on existing PACCHs of either DL or UL TBFs.
Sponsored-by: On-Waves ehf
This reverts commit e91bd3babd.
That commit seems to cause hanging DL TBFs when there was a RACH
based UL TBF establishment while it that TBF is active. This could be
caused by the use of a different PDCH for the SBA.
Conflicts:
tests/tbf/TbfTest.cpp
tests/tbf/TbfTest.err
The FN of the data_ind taken from the DSP are monotonic, so latency
does not affect the detection of poll timeouts if these FN are used.
If the FN is larger than a poll_fn value, it can safely be assumed
that the poll response will not arrive later on.
Currently a max_delay of 60 frames is used, which has the drawback
that additional ~250ms will pass until a lost ACK is detected.
Using the data_ind's FN alone breaks the poll timeout detection if
there are no other MS sending data blocks.
This commit adds BTS::set_current_block_frame_number that is called
with the FN taken from data_ind messages. The max_delay is set to 0
which removes the additional delay, when this FN is used to detect
poll timeouts. So the average additional delay decreases with the
number of data_ind per time. The current_frame is updated unless it
seems to have been updated already (assumed if 0 < cur_fn - block_fn
< 500). Thus the time_ind has still priority to update the
current_frame value.
Sponsored-by: On-Waves ehf
This commit adds the relevant frame number to the "poll timeout"
logging message. In addition, logging is added to the places where
poll_fn gets set.
The goal is to track down the source for frequent "poll timeout"
messages.
Sponsored-by: On-Waves ehf
Currently when calling GprsMs::attach_tbf and a TBF of the same
direction already exists, the old TBF gets detached from the MS
object.
Therefore that TBF object loses access to that MS object including
for instance TLLI and IMSI.
This leads to failing DL TBF reuses, since the downlink assigment
cannot be sent on the PACCH later on because that must be sent on the
old DL TBF which ms() is NULL and the new DL TBF cannot be retrieved.
This commit fixes this bug by changing the GprsMs implementation to
keep a list of replaced (old) TBFs. TBFs are only removed when they
are being detached explicitely (see tbf_free and set_ms).
Addresses:
tbf.cpp:741 We have a schedule for downlink assignment at uplink
TBF(TFI=1 TLLI=0xf35a680e DIR=UL STATE=RELEASING), but there is no
downlink TBF
Sponsored-by: On-Waves ehf
This tests the usage of an existing TBF that is no longer in FLOW
state to request a new DL TBF via the old TBF's PACCH.
The test triggers a bug that breaks the association between both TBF
objects, resulting in packet loss and transmission stalling.
Sponsored-by: On-Waves ehf
Currently the assignment is completed by manipulating the state of
the TBF objects directly by setting the state fields to fixed values.
This way, the PCU's code that is responsible to update the state
accordingly is not tested.
This commit changes this to simulate RLC Control Acknowledgement
messages instead.
Sponsored-by: On-Waves ehf
The block number can always be deduced from the frame number. The
current test code handles the block number explicitely, which makes
the code more complex and has also led to block number errors cause
by not wrapping the numbers (valid block numbers range from 0 to 11).
This commit changes send_rlc_block to always compute the block number
based on the frame number. It also turns the block_nr into an
optionaly output-only parameter.
Sponsored-by: On-Waves ehf
Currently the pending LLC packets are lost in some cases when MS
objects are merged, for instance after a RACH when there were 2 MS
object for the same MS (they get merged, when the TLLI is known for
both objects).
This patch modifies GprsMs::merge_old_ms to move all pending LLC
packets (if there are any) to the current MS object.
Sponsored-by: On-Waves ehf
Currently all active TBF of an MS are killed if a Packet Resource
Request is received from the MS. In general this happens after a RACH
request. This does not happen after a resource request that has been
included into a Downlink Ack/Nack.
Sometimes an UL TBF is requested by an MS via RACH while a DL TBF is
running for instance to send a TCP Ack. This can happen, if a former
request via PACCH did not work.
This commit removes the killing of the DL TBF from
gprs_rlcmac_pdch::rcv_resource_request().
Sponsored-by: On-Waves ehf
This adds tests for
- RA update with RACH for the RAUpdateComplete message
- RACH for UL while DL is active (LLC queue not empty)
Sponsored-by: On-Waves ehf
This commit fixes several issues:
- Set MS class in request
- Set IMSI in establish_ul_tbf_two_phase
- Fake assigment acknowledgement in establish_ul_tbf_two_phase
- Fix TFI bit offset to 1 (was 2)
Sponsored-by: On-Waves ehf
Currently the functions test_tbf_single_phase and test_tbf_two_phase
do the test logging, BTS intialisation, and the complete message
sequencing on their own. Therefore they cannot be used to test more
complex sequences like TBF reestablishment.
This commit moves the code that does the actual messaging into own
functions. The frame number handling is generalised which also fixes
a block number wrapping error on the way.
Sponsored-by: On-Waves ehf
Currently the merging of the meta information (MS class, IMSI) takes
place in gprs_rlcmac_tbf::merge_and_clear_ms(). This makes it
difficult to merge the internal state and does not directly relate to
TBFs anyway.
This commit moves this into a new method GprsMs::merge_old_ms.
Sponsored-by: On-Waves ehf
Currently if an MS retries to access the PCU by using RACH and if
there is already an entry for that MS, a duplicated MS object
referring to the same TLLI is created. This is caused by blindly
setting the TLLI without querying the MS storage to avoid
inconsitencies.
This leads to several entries in the MS storage that are assigned to
the same TLLI. If that happens, 'show ms all' can display multiple
entries with the same TLLI (note that an MS object can belong to
several TLLIs, so there might be an intersection that is not visible
in the list) or 'show tbf all' can show entries with MS_CLASS == 0 in
some cases.
This commit changes update_ms() to merge and clean up old entries
that belong to the given TLLI if they exist. Some data (like the MS
class) is copied to the new MS object.
Note that TBF belonging to the old MS object are deleted immediately
if they have not registered a timer.
Sponsored-by: On-Waves ehf
Currently when receiving a PACKET DL ACK/NACK message with the Final
Ack Indicator bit set, the TBF's state is set to
GPRS_RLCMAC_WAIT_RELEASE but T3193 is only started when the LLC queue is
empty. Otherwise the reuse_tbf() method is called to establish a new
DL TBF. In that case, the timer is not started. This will leave the
current TBF without a timer so it is potentially not released later
on.
This is recognisable by sticky entries in the output of the
'show tbf all' command and possibly allocation failures if there are
too many of them.
This commit changes the code to always start T3193 to make sure, that
a timer is always active when the the state is set to
GPRS_RLCMAC_WAIT_RELEASE.
Note that TS 44.060, 9.3.2.6 requests to release the 'old' TBF
immediately in some cases, which is not implemented by this change.
This will lead to a longer reservation period of the TFI only, which
is safer than reassigning it too early.
Sponsored-by: On-Waves ehf
Currently the TBFs are registered in a TFI indexed array within the TRX
objects. TBFs can be searched globally by TFI and TRX number. This
conflicts with the use of the same TFI for different TBF on different
PDCH. This use case requires the specification of the PDCH as
additional search dimension.
This commit moves the TFI index TBF arrays into the PDCH objects. The
related methods are updated accordingly.
Ticket: #1793
Sponsored-by: On-Waves ehf
Currently the TFI are managed per TRX, thus only a maximum of 32 TBF
per direction and per TRX are possible simultaneously.
This commit modifies algorithm_a() to allow the sharing of TFI
between different PDCH. Since algorithm A only assigns a single slot
to each TBF, the TFI of each PDCH can be assigned independently.
This increases the maximum to 32 TBF per direction and per PDCH
concerning the TFI allocation.
Ticket: #1793
Sponsored-by: On-Waves ehf
Currently the TFI and the TRX have to be determined before the actual TBF
allocation function is called, passing TFI and TRX number as
parameters. This does fit to TFI reuse for different slots, since
this were tightly coupled with the slot selection.
This commit just moves the TFI selection into the alloc_algorithm
functions. The tfi parameter is removed from the the TFI alloc
functions. The trx parameter is changed into use_trx to optionally
limit the trx selection (same semantics like in tfi_find_free).
Sponsored-by: On-Waves ehf
Aravind Sirsikar