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
Currently is is rather expensive to get TFI and USF usage per PDCH,
because the TBFs need to be scanned to get that information.
This commit adds corresponding bit sets which get updated by the
attach_tbf/detach_tbf methods of the gprs_rlcmac_pdch class.
Sponsored-by: On-Waves ehf
Since both TBF are based on the same reservation which means that
they should be compatible with respect to the slot usage, and since
the new TBF has not been forced to single slot usage, an update of
the allocation is not necessary now.
This commit removes the call to update() from within reuse_tbf().
Sponsored-by: On-Waves ehf
The call to tbf_alloc_dl_tbf misses the pointer to the GprsMs object
which is already known in that case (tbf_reuse). This leads to a full
reallocation of the PDCH slots, which is possibly incompatible with
the old set of slots. This can result in hanging TCP connections and
TCP connection failures.
This commit replaces the old NULL value by the actual GprsMs object.
Since the set_ms() is also done within the tbf_alloc_dl_tbf method,
that call is removed.
Sponsored-by: On-Waves ehf
Currently algorithm A bases its time slots selection on the number of
TBF actively using the PDCHs. This statistically prefers the first
time slots, especially with short living TBFs. So when the first TBF
is triggered by an uplink transfer (which generally results in a
short-lived TBF) the potentially longer living DL TBF will be bound
to the same slot. When another MS then requests an uplink TBF, it
will get the same slot (no UL TBF currently active).
This commit changes the algorithm to base its selection on reserved
slots instead.
Sponsored-by: On-Waves ehf
Currently only the first enabled PDCH will be used. Beside the
throughput this will also limit the number of TBFs:
- number of UL TBFs <= 7
- number of DL TBFs <= 32
This commit changes the allocation algorithm to use the PDCH with the
least number of attached TBFs. This will improve the troughput in
both directions and the UL limits:
- number of UL TBFs <= min(32, N_PDCH * 7) UL TBFs
Ticket: #1794
Sponsored-by: On-Waves ehf
Currently the PDCH object do not know anything about the TBFs using
them. To make the slot allocation load dependant, at least some
numbers are required.
This commit adds TBF counters (one per direction) and the related methods
attach_tbf, detach_tbf, and num_tbfs to gprs_rlcmac_pdch.
Sponsored-by: On-Waves ehf
Currently the MS object are created when the TLLI gets known.
Therefore some information (TA, MS class) must be stored in the TBF
itself and is copied to the MS object later on. This would get even
more complex, if the allocation algorithms were extended based on
this scheme.
This commit ensures, that an MS object will always be created on TBF
allocation, even if the TLLI is not yet known. These 'anonymous'
objects are still managed by the MS storage. To avoid dangling
entries without a TLLI there (which cannnot be retrieved anyway), the
timer in the MS objects is not started after all TBF have been
detached, so that they get deleted immediately in that case.
Note that an MS object can still be removed (e.g. by replacement)
from an existing TBF, so tbf->ms() can be NULL.
Ticket: #1794
Sponsored-by: On-Waves ehf
When the MS is pinged with a longer interval, many packets get lost
even if the GprsMs object is kept. If the interval is above the time
where the DL TBF is in state FLOW (mainly influenced be the
dl-tbf-idle-time command), an new TBF must be requested via AGCH for
each ICMP PING message.
Currently the LLC frame containing the PING is immediately stored
in the TBF and gets lost, if TBF establishment fails for some reason.
This commit moves all calls to put_frame() to schedule_next_frame(),
where the data is moved from the LLC queue to the frame storage
within the TBF object. This method is only called from within
create_new_bsn() when the TBF is in the FLOW state and the frame is
going to be encoded immediately.
At all other places, where put_frame() has been called before, the
LLC message is just appended to the LLC queue in the GprsMs object.
This change effectively simplifies the related code parts, since
date/len information and discard notifications is no longer needed
there.
Ticket: #1759
Sponsored-by: On-Waves ehf
Currently LLC frames are lost or even reordered when the TBF has be
established via the AGCH and the procedure fails for some reason.
This test tries to reproduce this behaviour by throwing away the
first TBF while calling the handle() method several times. The
results of create_dl_acked_block() are checked against expected
values (this is currently party disabled because the bug still
persists).
Ticket: #1759
Sponsored-by: On-Waves ehf
Currently the current CS value is stored in the cs field of
gprs_rlcmac_tbf and initialised when it is used the first time.
This commit adds separate fields for UL and DL CS values to the
GprsMs class and provides corresponding getter methods for GprsMs and
gprs_rlcmac_tbf.
Ticket: #1739
Sponsored-by: On-Waves ehf
The ms_class value is a property of the MS and thus belongs to the
GprsMs class. Nevertheless the MS object is created after the TLLI
gets known, so the value still has to be stored in the TBF initially.
This commit add the ms_class value to the GprsMs class and introduces
TBF accessor functions which either access that object or, if that is
not available, the value stored locally.
Ticket: #1674
Sponsored-by: On-Waves ehf
The TA value rather relates to an MS and not to a single TBF. So all
TBFs share the same TA value. Currently the TA value is stored per
TBF and eventually copied from an old TBF to a new one. It is in
general only passed with an RACH request when the TLLI and thus the
MS is not yet known.
This commit adds a TA member to the GprsMs class and uses that one
when the TBF is associated to an MS object. Since the TBF is not
always associated with an MS object (after RACH or when it has been
replaced by another TBF), the TA value is still stored in each TBF
and that value is used as long as no MS object is being associated.
Sponsored-by: On-Waves ehf
These tests cover the message exchange from receiving from the first
RACH request to the first data block when establishing an uplink TBF.
This will be used to check, whether TA and other values are passed to
an MS object correctly.
In addition, the RX RACH log message in rcv_rach is extended to
contain the single block fn.
Sponsored-by: On-Waves ehf
Currently a new TBF is chained to an existing older one, either of
the other direction (active or releasing) or of the same direction
(releasing). This does not work properly work if and uplink and a
downlink TBF are being established at the same time while an old TBF
is being released. In that case, one of them is thrown away and the
pending procedure is cancelled.
The chaining is no longer necessary since the GprsMs objects have
been introduced which keep track of the active TBFs.
This commit removes the TBF members m_new_tbf and m_old_tbf and the
related methods and code paths.
Note that a new TBF can replace an older TBF entry of the same
direction within an MS object when it is associated with an MS (e.g.
by TLLI or because it is assigned via another, already associated
TBF). In that case, the old TBF is no longer associated with an MS
object.
Ticket: #1674
Sponsored-by: On-Waves ehf
Jacob Erlbeck