Currently the MCS schemes are not supported when the leak rate is
being computed. This leads to a lower value for the leak rate, thus
limiting the throughput to GPRS-like ranges.
Use the payload size reported by GprsCodingScheme instead.
Sponsored-by: On-Waves ehf
That IE may contain inaccurate or completely bogus data.
This commit disables the parsing.
Note that this should be replaced by a config option.
Sponsored-by: On-Waves ehf
In case there is no MS object present that matches a DL UNITDATA,
the EGPRS class is currently assumed to be 0, since the Radio
Access Capabilities IE is not fully decoded if present.
This commit uses the CSN.1 decoder to parse the IE and uses the
same functions like the uplink related code does to get the GPRS
and EGPRS multislot classes.
Remove the old parse_ra_cap_ms_class function.
Sponsored-by: On-Waves ehf
Just keep this for later reference, since a CSN.1 decoder based
implementation will be used.
This reverts commit b37ab36bb14d2d2c1363fbe521cd19984d0c3d4c.
Add an extended parse_ra_cap function based on the existing
parse_ra_cap_ms_class which also parses up to the EGPRS related
fields.
Sponsored-by: On-Waves ehf
ASAN has found improper deletion of objects. These only occur
on shutdown but makes it impossible to run the test cases with
full ASAN support.
This commit fixes some of them and deactivates the freeing of the_pcu.bctx
which may cause a corruption in BTS::~BTS() later on.
Note that the latter is only a work-aound and should be fixed
properly. It will leak bctx objects, but this is currently not
critical, since gprs_bssgp_destroy is only called once, immediately
before a call to exit().
Ticket: OW#1572
Sponsored-by: On-Waves ehf
The multislot (MS) class and the EGPRS MS class can also be passed
via BSSGP in an MS Radio Access Capability element which can
optionally be contained in a DL-UNITDATA PDU. While this case is fully
supported for GPRS, the EGPRS MS class in BSSGP messages is ignored.
This commit extends gprs_rlcmac_dl_tbf::handle to pass the EGPRS MS
class, too.
Note, that the EGPRS class is not yet taken from the CSN.1 RA
capability and is always set to 0. Note also, that append_data
still uses ms_class only.
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 the signal S_NS_ALIVE_EXP emitted by the NS layer if the
alive check has timed out too often is ignored. This prevents the PCU
from reconnecting to the SGSN if it has not been accessible for some
time.
This commit modifies nsvc_signal_cb to reset the NSCV if
S_NS_ALIVE_EXP is sent, so that the PCU continues to send NS RESET
message if that happened.
Sponsored-by: On-Waves ehf
Currently the initial_cs_dl value is used to compute the maximum leak
rate. This can be too low if adaptive CS selection is used.
This commit changes gprs_bssgp_tx_fc_bvc to derive the max CS level
from the configuration.
Sponsored-by: On-Waves ehf
Currently the values Bmax/R default MS are computed under the
assumption than min(4, N_PDCH) DL slots are allocated for an MS, even
if multislot assignment is not enabled.
This commit changes the computation to assume 1 DL slot if algorithm
A is selected or the dynamic algorithm is used and has disabled
multislot assigment due to high load.
Sponsored-by: On-Waves ehf
Some struct timeval pointer arguments do not have the const qualifier,
albeit the methods do not write to the structures. The next commit
will change related pointers to const, so this commit provides the
required constness.
Sponsored-by: On-Waves ehf
Currently the delay_sum is stored in 64 to avoid overflow errors.
But only the result of tv_sec * 1000 is casted to 64 bit, resulting
in an overflow if the accumulated queue delay reached 25 days (which
will not happen in practice, unless there are >200k LLC messages with
a max of 10s delay each in the queue). If that were the case, the
only impact would be a wrong number in a log message and in the BSSGP
FLOW CONTROL message.
This commit changes the calculations so that they are done in 32 bit
only, rather than to do the calculation in 64 bit properly.
Fixes: Coverity CID 1298705
Sponsored-by: On-Waves ehf
Currently it is assumed, that btcx is non-NULL. The btcx is only used
to obtain the BVCI in some log messages.
This commit changes that by using -1 as shown BVCI value.
Fixes: Coverity CID 1040961
Sponsored-by: On-Waves ehf
According to the specification (GSM 04.08/24.008, 4.7.1.5) after a
new P-TMSI has been assigned, the old P-TMSI must be kept basically
until it has been used by both sides. Since the TLLI will be derived
from the P-TMSI, the old TLLI must also be kept until the new TLLI
has been used by both MS and SGSN.
This commit modifies the TLLI handling of GprsMs accordingly.
set_tlli() is only used with TLLIs derived from MS messages,
confirm_tlli() is used with TLLIs derived from messages received from
the SGSN. tlli() returns the value set by the MS. check_tlli()
matches each of the TLLI used by either MS or SGSN as well as the old
TLLI until it has been confirmed.
Sponsored-by: On-Waves ehf
Currently the tag value in FLOW CONTROL BVC messages is always 1.
This commit changes the implementation to increment that value with
each of the FLOW CONTROL BVC messages that is sent to the SGSN.
Sponsored-by: On-Waves ehf
The specification 28.018, allows to transmit the average LLC downlink
queueing delay in FLOW CONTROL BVC messages (BVC Measurement IE, see
GSM 28.018, 10.4.4 and 11.3.7).
This commit extends gprs_bssgp_pcu.cpp to compute the average delay
time between two subsequent FLOW CONTROL BVC messages. The average is
implemented as an arithmetic average without any weighting.
Ticket: OW#1432
Sponsored-by: On-Waves ehf
Currently the bucket size is by default being computed based on the
leak rate and the expected life time of LLC frames. The latter is
either taken from 'queue lifetime' (if given) or a fixed value is
used. Using 'queue lifetime' has the drawback that it sets a 'hard'
limit, since frames will be dropped if they stay in the queue
for a longer time.
This commit adds a VTY command to specifically set the time used for
the computation of the bucket size advertised to the SGSN. It does
not affect the PCUs queue handling in any way. If the bucket time is
not set (or if the 'no' command has been used), the old behaviour
(see above) is applied.
The following VTY commands are added (config-pcu node):
- flow-control bucket-time <1-65534> Sets the time in centisecs
- no flow-control bucket-time Don't use this time
Ticket: OW#1432
Sponsored-by: On-Waves ehf
Currently the PDCH assignment and coding scheme does not influence
the values transmitted by the FLOW-CONTROL-BVC messages.
This commit adds the computation of those values. If the leak rate is
not given explicitly, it is derived from the number of PDCH and the
allowed coding scheme. If the BVC bucket size is not given
explicitly, it is derived from the leak rate and the maximum buffer time.
The latter is taken from the 'queue lifetime' command (or 10s if this
has not been used). The MS default bucket size is set to 50% of the
BVC bucket size. The MS default rate computation assumes, that each MS
only supports up to 4 time slots for GPRS RX.
Sponsored-by: On-Waves ehf
Currently the FLOW-CONTROL_BVC message contains fixed values: The tag
is 1, the BVC bucket size is 6MB, the BVC bucket leak rate is
820kbit/s, the MS bucket size is 50kB, and the MS leak rate is
50kbit/s.
This commit makes the BVC parameters configurable and adds the
following VTY commands:
- flow-control force-bvc-bucket-size <1-6553500>
- no flow-control force-bvc-bucket-size
- flow-control force-bvc-leak-rate <1-6553500>
- no flow-control force-bvc-leak-rate
- flow-control force-ms-bucket-size <1-6553500>
- no flow-control force-ms-bucket-size
- flow-control force-ms-leak-rate <1-6553500>
- no flow-control force-ms-leak-rate
The 'no' variants restore the default behaviour.
Sponsored-by: On-Waves ehf
Currently incoming BSSGP STATUS messages are just logged and apart
from that ignored. Since it is possible that the gbproxy can
eventually send both valid replies (from the primary SGSN) and
STATUS(unknown BVCI) messages (from the secondary SGSN). Since the
PCU assumes in this case that the BVC has been successfully reset and
unblocked, it will not send a BVC RESET message after receiving an
NS_UNBLOCK.
This commit changes gprs_bssgp_pcu_rcvmsg to pass BSSGP STATUS
messages to bssgp_rcvmsg() which will in turn call bssgp_prim_cb()
with primitive NM_STATUS. Then the BVC RESET or UNBLOCK procedure
will be started if the IE in the message matches and the PCU assumes
that the BVC should have been successfully reset and unblocked
respectively while the STATUS message tells otherwise.
Note that bssgp_rcvmsg() from libosmocore is otherwise used for the
SGSN side only, albeit it generally just decodes messages, does basic
protocol handling and eventually invokes PRIM indications. The only
exception here is the handling of BVC RESET, which is implemented
specifically for the SGSN.
Ticket: OW#1414
Sponsored-by: On-Waves ehf
Currently the timer T1 and T2 are hard-coded to 1s which is pretty
low in consideration of a possible high latency connection to the
SGSN.
This commit introduces macros for the timer values and sets them to
30s.
Sponsored-by: On-Waves ehf
The current code tries to recover from dropped connections and resets the
pcu state so it can keep running. However, this never worked correctly
which is why the -e option is used. This option exits the pcu as soon as
the internal state needs to be reset.
This patch removes this option and makes this behaviour default.
Ticket: SYS#390
Sponsored-by: On-Waves ehf
So we had one intended line inside the if for "SMS VALUE" and
at the same time one line with "SMS VALUE" at the same indention.
Assume it is copy and paste and remove the line. Currently we
are only parsing the ms_class so this change should not have any
semantic change.
Fixes: Coverity CID 1058761
The TBF should use the IMSI to identify a block flow but all
handling is spread across the entire code. Start to clean this
up by moving relevant code into the tbf file. Afterwards one
can clean up and add more internal structure.
For mocking/unit-testing/emulation (and a dual trx-systems) having
global state is quite bad. Cut back on the usage of the global
struct gprs_rlcmac_bts. It also makes the complexity of certain
routines more clear.
Decrease the number of lines of a single method by splitting things up.
The fewer lines of code, branches and side-effects in a method, the easier
it will be to understand. The other benefit is that one can start creating
unit tests for the some parts of the code.
One of the issues with not properly re-setting everything is that
due the global state it is not clear which variables belong together
and how long it exists. Begin with creating a osmo_pcu and moving
things into this class.
Think of an organic cell, this commit is introducing the cell wall
around it... and defines what is inside and what is outside of it.
The PCU does not properly re-set the state when the connection to the
BTS is lost (and the SGSN potentially is re-started during that). This
results in the BSSGP BVCI > 1 remaining blocked and no data will be
accepted by the SGSN.
Add the '-e' option and exit the PCU when the BSSGP/NS are getting
destroyed.
osmo_timer_del is an idempotent operation. There is no requirement
to check if it is running. If you don't want a timer to run, delete
it. Maybe one should have called the method _unschedule, _cancel to
make this more clear.
The timing advance of any TBF is stored when it ends. Whenever a new TBF
with the same TLLI is created (downlink TBF), the stored TA is recalled.
This algorithm assumes that the mobile does not move too fast during
transfer. Also the mobile must start a connection in order to get correct
initial timing advance.
This algorithm does not implement the timing advance procedure as defined
in TS 04.60. To implement the standard timing advance procedure, the BTS
must decode RACH on certain bursts, the mobile is expected to send them.
This requires much more complexity to a transceiver like USRP/UmTRX or
Calypso BTS.
The algorithm was tested at TA >= 8 and works quite well.
The measurements include:
- DL bandwidth usage
- DL packet loss rate
- DL measurements by mobile
- UL measurements by BTS
In order to receive DL measurements from mobile, it must be enabled via
system information message at BSC.
Jacob Erlbeck
Daniel Willmann
Harald Welte