We should really be using monotonic clock in all places that
gettimeofday is used right now. Since clock_gettime() uses timespec,
let's move all code to use timespecs instead to avoid having to convert
in several places between timespec and timeval.
Actually use osmo_clock_gettime() shim everywhere to be able to control
the time everywhere from unit tests.
Change-Id: Ie265d70f8ffa7dbf7efbef6030505d9fcb5dc338
Receive an Application Information Request from the BTS via PCU
interface. Construct a Packet Application Information message from it
(3GPP TS 44.060 11.2.47) and send it to all MS with active TBF.
The TTCN-3 test infrastructure to test this feature is not quite ready
yet, so I've added C unit tests instead.
Related: OS#4048
Change-Id: Ie35959f833f46bde5f2126314b6f96763f863b36
Add function to encode MCS value as proper EDGE or GPRS Channel Coding
value according to 3GPP TS 44.060 and corresponding helpers.
Use it for everything except IA Rest Octet encoding which is done in a
follow-up patches to make sure that we distinguish between
encoding-related changes to test output and unrelated changes.
Change-Id: I127fb29f5aaf77a7f6c4c565dfeb3b711af9845d
In preparation for Channel Coding Command encoder in follow-up patches
let's add necessary helpers. Those are similar to previously used
helpers from GprsCodingScheme class but without CamelCase and with less
typo chances between Gprs and Egprs cases.
Change-Id: I6699cbc8d7ae766fa4d2b3d37e5f9ff1cf158b7e
Move Mode (EDGE/GPRS) definition and related functions outside of
GprsCodingScheme class. This allows us to use standard libosmocore
value_string functions.
Change-Id: I3baaac7f1ca3f5b88917a23c1679d63847455f47
Move generic MCS enum to C header file to simplify further modifications
to GprsCodingScheme class in follow-up patches. This also allows us
to use standard libosmocore value_sting functions in upcoming patches
for IA Rest Octet encoding/decoding.
Related: OS#3014
Change-Id: I993b49d9a82b8c7ad677d52d11003794aeabe117
Previously some of the errors in update_cs_ul() call were silently
ignored. Let's log all those as errors with appropriate message.
Note: test output needs updating because we do not (yet) set proper meas
struct in TBF tests. That's likely wrong but it's better to update tests
in a separate commit.
Change-Id: I4084fb281dd9dad04a2a3a68cac2a8f7b462548e
Previously MAX_GPRS_CS was used for both EDGE and GPRS which means that
we waste extra memory in GPRS case. It also leads to misleading
name. Let's fix this by introducing separate definitions for GPRS and
EDGE cases and use them as appropriate in limit checks.
Change-Id: I3ae1ee64ec8e80247b8fe669cc79505b4dadf58f
Many files include unnecessary headers and don't include headers which
are actually used. Because of that combined with the fact that OsmoPCU
is a mixture of C and C++, it makes it hard to modularize code. Fix
this (using iwyu [1] tool):
* add missing headers
* remove unused headers
[1] https://include-what-you-use.org/
Related: OS#1539
Change-Id: I8c9f488a43b099c72b2d30d3245e7ba50872fc00
The coding scheme converted to number make sense only if it's
valid. This is implicitly assumed by the code using this conversion as
non-zero value. Make those assumptions explicit with OSMO_ASSERT().
Change-Id: I8f62627b7b7b89dfa1b0d1a7e71b95b2c40fdffa
Fixes: CID70466
We have seen that UL MCS5- MCS9 link adaptation has not been implemented in current PCU implementation.
If the MS slowly moves far away from the BTS, the UL MCS will always stick at MCS9 no matter UL link quality values leading to poor data service experience.
The UL MCS is expected to adapt from MCS9 -> MCSx due to bad UL quality.
Below PCU traces indicate that UL MCS is quickly increasing to MCS9 (max MCS 9 was used in this test) and it never changes to other UL MCS due zero thresholds.
<0004> gprs_ms.cpp:670 MS (IMSI ): Link quality 23dB (23dB) left window [0, 0], modifying uplink CS level: MCS-6 -> MCS-7
<0004> gprs_ms.cpp:670 MS (IMSI 000): Link quality 23dB (23dB) left window [0, 0], modifying uplink CS level: MCS-7 -> MCS-8
<0004> gprs_ms.cpp:670 MS (IMSI 000): Link quality 23dB (23dB) left window [0, 0], modifying uplink CS level: MCS-8 -> MCS-9
Change-Id: I9272c337ad6399da4a47cc6e2736e25f24e099d8
Adds spb counters at BTS level(show bts statistics).
Adds RLC/MAC downlink control msg at ms level(show ms imsi <imsi_val>).
Adds the number of coding schemes counter for UL at TBF level.
Change-Id: Icbe4ba95e34bea89ee36f532d099db68204b7c38
* initialize with invalid TA instead of making assumption that phone is
located within 550 meters (TA=0)
* only set valid TA
Change-Id: Idfc40ff0c11bdac13d9e28fbfa4e95dfc6b735b0
Related: OS#1526
Function is added to parse the EGPRS header type 1 in uplink tbf path.
along with configuration parameter updation to reflect max mcs in UL
Change-Id: I13c250e2e07377982ac3f29745f3cffd4088552a
Reviewed-on: https://gerrit.osmocom.org/270
Reviewed-by: Harald Welte <laforge@gnumonks.org>
Tested-by: Jenkins Builder
This is the second attempt to fix what looks like a copy and paste
issue. The code assigns m_current_cs_ul and then compares the _dl
variant, then assigns m_current_cs_ul with a default value. It seems
to indicate that _ul should be used.
Fixes: Coverity: CID 1351733
Roll-out the refactoring change. The code did not include the
necessary update to the test result and there are some concerns
about it in itself and the right approach would have been to
fix the copy and paste issue, then do the refactoring.
This reverts commit 22d7e75e1f.
Previously this code used too much copy-paste of boilerplate code which
is error-prone and hard to read. Factor out actual (M)CS assignment into
separate function and use it for both DL and UL cases in respective
mode.
Fixes: Coverity: CID 1351733
Currently the queue length is overwritten by the remaining chunk
length, which should be added instead. This may result in a lower
CS/MCS value than expected.
Add the chunk length instead if the TBF is present.
Sponsored-by: On-Waves ehf
The PACCH is specific to an MS and may change when a TBF is
established or removed (see TS 44.060, 8.1.1.2.2). For multislot
class type 2 phones, more than one timeslot may be used to transmit
RLC/MAC control messages.
Add a method that returns a set of TS which can be used for the
PACCH.
Sponsored-by: On-Waves ehf
Currently the coding scheme gets reset when GprsMs::set_mode()
is called even if the mode did not change.
Make sure, that the CS is only reset, if it is not compliant to the
new mode.
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 casts from gprs_rlcmac_tbf to gprs_rlcmac_ul_tbf and
gprs_rlcmac_dl_tbf are done by using static_cast. This doesn't provide
protection against converting a gprs_rlcmac_ul_tbf pointer to a
gprs_rlcmac_dl_tbf pointer and vice versa.
This commit provides two functions as_ul_tbf and as_dl_tbf, that
behave similar like dynamic_cast but use the direction field instead
of RTTI.
Sponsored-by: On-Waves ehf
The EGPRS MS class ist contained in the MS_RA_capability information.
Its presence indicates, that the MS is able (and willing) to use
EGPRS.
This commit implements basic support for retrieving, storing, and
showing it in the VTY. The information is stored in the MS object.
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
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 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
The current default interval is 2s which seems to be too short when
the DL TBF has to be established. This may cause freezing or really
slow TCP connections.
This commit increases the default value to 4s. When the
dl-tbf-idle-time is set, DL TBF are established less frequent, so
smaller values (like 2s or below) can be used to improve the average
latency when the load is high.
Sponsored-by: On-Waves ehf
When doing an RA Update the network can request to change the TLLI.
In this case, there can be 2 MS objects with different TLLI for a
single real MS. The first is associated with the old TLLI and the
IMSI, while the second is associated with the new TLLI and no IMSI if
it had been created for the uplink TBF. When the first message with
the new TLLI and the IMSI arrives from the network, the PCU is able
to detect this.
Currently this is not handled properly. The TBFs of the old MS object
are not cleaned up properly, keeping the old MS from being deleted.
This patch modifies gprs_rlcmac_dl_tbf::handle to check for this and
if neccessary to move an existing DL TBF and to clean up the old MS
object to ensure its deletion.
Sponsored-by: On-Waves ehf
Currently packets are only dropped if they have reached their maximum
life time. This leads to LLC queues being constantly filled under
load, increasing the latency up to the maximum life time. This kind
of bufferbloat hinders TCP's congestion avoidance algorithms. To keep
the queues short, the CoDel active queue management algorithm can be
used.
This commit changes to llc_dequeue method to apply the CoDel
algorithm to selectively drop LLC frames before they passed to the
TBF layer to be encoded in BSNs. This feature is currently disabled
by default.
The CoDel state is managed per MS since the LLC queues are also kept
in the MS objects.
Note that there is still some buffering in the TBF objects, in the
worst case (CS4) 3.5kByte + LLC-MTU octets are stored there. The
resulting additional packet delay is not (yet) taken into account for
CoDel.
Also note that configuration changes are applied to new MS objects
only.
The following VTY commands are added to the 'pcu' node:
- queue codel activates CoDel, the interval is selected by
the implementation
- queue codel interval <1-1000>
activates CoDel with a fixed interval given
in centiseconds (10ms-10s)
- no queue codel deactivates CoDel
Which interval value to use is still an open issue. For high speed
links (e.g. Ethernet), CoDel suggests 100ms. For slower links, the
expected RTT is recommended. The current implementation uses a
default value of 2000ms.
Measurements:
Note that the following measurements depend on several other factors,
most notably the interaction with the SGSN's flow control. They are
just examples to give an idea how CoDel might influence some
parameters.
The measurements have been done with a single E71, first with a
running ping only (Idle), then with an additional TCP download
of a 360k file (Busy). The CoDel interval was set to 1s.
- Idle :
ping ~400ms, avg queue delay 0ms, dropped 0
- Busy, No CoDel:
ping ~6s, avg queue delay 4-6s,
dropped 0, scheduled 948, duration 54s
- Busy, CoDel:
ping 500-1500ms, avg queue delay ~600ms,
dropped 77, scheduled 1040, duration 60s
More measurements with two MS downloading in parallel (two
independant measurements per case).
- Busy, No CoDel:
dropped 0, scheduled 1883, duration 121s
dropped 19, scheduled 2003, duration 133s
- Busy, CoDel:
dropped 22, scheduled 1926, duration 116s
dropped 22, scheduled 1955, duration 108s
Sponsored-by: On-Waves ehf
Currently there is no simple way to determine, whether the MS object
protected by a guard will continue to exist after the guard object is
destroyed.
This patch adds a is_idle() method that will return true if the MS
object is just kept by the guard from being idle. In that case, the
MS object would either be deleted or return true for
GprsMs::is_idle() after the guard's destruction, provided that no
TBF attachment took place in between.
Sponsored-by: On-Waves ehf
In contrast to the slots currently used by existing TBFs, the
reserved slots refer to the time slots that can be used for newly
allocated TBFs without causing conflicts (given that the first common
TS does not change). They correspond to the potential use of the
PDCHs and can be used to achieve a more uniform slot allocation.
This commit adds bit set based methods to GprsMs and gprs_rlcmac_trx
and a counter to gprs_rlcmac_pdch. The current TRX will also be
stored in the MS object.
Sponsored-by: On-Waves ehf
To avoid the need for a switch or conditional statement when needing
a TBF from an MS object in direction independant code, this method
contains that case distinction. For additional flexibility, a
reverse() function is added to get the opposite direction.
Sponsored-by: On-Waves ehf
This method gets the index (0 based) of first common time slot used
by the TBFs attach to it. It expects that all of them have the same
notion of this. If no TBF is attached, -1 will be returned.
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
If just a few bytes are left to send to the MS, it makes sense to
reduce the coding scheme level to increase the throughput. This
has been shown by Chen and Goodman in their paper "Theoretical
Analysis of GPRS Throughput and Delay". See their throughput over C/I
measurement graphs (figures 4 and 5 in the paper) for details.
This commit implements a simplified CS downgrade feature for the
downlink. The coding scheme will be downgraded if there are only a
few octets are left to be send over the TBF (see the
downgrade-threshold command below) and the NACK rate is not low (the
CS will not get degraded on a high quality RF link). As an exception,
CS-3 will be degraded to CS-1, since CS-2 does not improve the
throughput in general when a few small packets are sent and the
signal fades slowly (see Chen/Goodman).
The following VTY command is added to the config-pcu node:
- cs downgrade-threshold <1-10000>
- cs no downgrade-threshold
to set the threshold of the number of remaining bytes to be RLC/MAC
encoded. The CS will only be reduced, if the number is below the
threshold. The 'no' command disables this feature completely. The
default value is 200 octets.
Sponsored-by: On-Waves ehf
Currently the NACK/unconfirmed ratio is already passed to the
corresponding MS object, but the value is not being stored there.
This commit adds a member and a getter method and include the values
into the output of the 'show ms' command.
Sponsored-by: On-Waves ehf
This commit extends the pcu_l1_meas structure by MS side measurement
values which are transmitted by PACKET DOWNLINK ACK/NACK and
PACKET RESOURCE REQUEST messages. The encoded values are remapped to
dB respectively % values. The values are stored in the corresponding
MS object (if there is one).
Note that the values are store as (rounded) integers, so some
different encodings are mapped to the same decoded value.
Sponsored-by: On-Waves ehf
Currently the UL CS values are set to the corresponding DL CS value,
eventually limited by a maximum value. This approach does not reflect
the general situation of the RF link between ME and BTS, which is
rather asymmetric e.g. due to a lower degree of TX efficiency of the
built-in antenna. This means, that UL and DL CS control should be
decoupled for better results.
This commit adds automatic UL CS selection based on the link quality
measurement parameter. Each coding scheme is mapped to a link quality
range. If the link quality value leaves that range, the current UL CS
value is increased/decreased accordingly. This value will be copied
when the next PACKET_UPLINK_ACK_NACK or PACKET_UPLINK_ASSIGMENT is
sent to the MS.
The following VTY command will be added to the config-pcu node:
- cs link-quality-ranges cs1 <0-35> cs2 <0-35> <0-35>
cs3 <0-35> <0-35> cs4 <0-35>
which sets the ranges for the four coding schemes. For instance the
example below reflects the current default values:
cs link-quality-ranges cs1 6 cs2 5 8 cs3 7 13 cs4 12
set the following ranges, where the overlapping is used to configure
a hysteresis:
CS1: -inf .. 6
CS2: 5 .. 8
CS3: 7 .. 13
CS4: 12 .. inf
Sponsored-by: On-Waves ehf
This commits adds the GprsMs::update_l1_meas() and GprsMs::l1_meas()
methods to store and access the measurement values. The internal
state is updated depending on which values are actually set.
In addition, these values are shown in the output of the 'show ms
imsi|tlli' command.
Sponsored-by: On-Waves ehf
Currently the timer can be started even if m_ul_tbf is attached.
Replace m_dl_tbf by m_ul_tbf to only start the timer if _both_ TBF
are detached.
Fixes: Coverity CID 1304683
Sponsored-by: On-Waves ehf
Currently the CS values can be increased to CS4 even when the "cs"
configuration command has been used with a lower value. The "cs"
command just sets the initial coding scheme, so other means are
needed to limit the selection. One approach is to use the CS flags
passed in SI, but these are currently ignored.
To make it possible to limit the CS selection by configuring the PCU,
this commit adds the following VTY commands to config-pcu:
- cs max <1-4> Limit DL and UL CS to the given value
- cs max <1-4> <1-4> Limit DL and UL CS separately (DL first)
- no cs max Don't limit
Ticket: #1674
Sponsored-by: On-Waves ehf
Currently the CS level is immediately increased if the error rate
drops below the lower threshold. Since the measurement values are not
damped, this behaviour leads to a quick return to higher CS values
even under bad radio conditions. Since with GPRS RLC/MAC blocks
cannot be resent with another coding scheme, increasing the CS value
should be done carefully.
This commit adds a blocking period that only allows higher CS values
if all error rate measurements were below the LOW threshold for a
certain amount of time (currently fixed to 1s).
Ticket: #1674
Sponsored-by: On-Waves ehf
To cope with transmission failures due to bad radio conditions, a
different coding scheme with more redundance can be used.
This commit adds an implemenation that is based on the Ack/Nack
ratio per PACKET DOWNLINK ACK/NACK message received from the MS.
Basically the CS level is decreased, if the block error rate goes
above cs_adj_upper_limit (default 33%), and it is increased, if the
rate drops below cs_adj_lower_limit (default 10%). Only blocks that
have been encoded with the current CS are taken into account.
Note that this approach doesn't measure the MS->BTS conditions and
that the measurement values reported by the MS are not taken into
account.
Ticket: #1739
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
Pau Espin
Vadim Yanitskiy
Oliver Smith