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Currently the slot selection of algorithm A is based on the current
slot usage by active TBF. Especially in the Dl after UL case which
reflects the commen use case "MS initiates TCP connection", the
resulting distribution is not optimal with respect to PDCH usage.
This commit changes the implementation to use the slot reservation
information instead.
Sponsored-by: On-Waves ehf
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Currently when using the test modes TEST_MODE_DL_AFTER_UL or
TEST_MODE_UL_AFTER_DL, the first TBF is deleted before the second is
allocated. The far more interesting case were to keep the first TBF a
little bit longer until the second TBF has been created and delete
then. This comes closer the the situation observed with real MS,
where the first TBF takes some time (timeout or waiting for Ack)
before it gets deleted and thus detached from the MS object.
This commit delays the call to tbf_free accordingly.
The effect can be observed in the results of the algo A tests, where
the uniform distribution of the allocated PDCH is lost.
Sponsored-by: On-Waves ehf
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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
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Currently the search of the "best" slot combination is done
separately from the UL slot selection, which can lead to an
allocation failure due to USF exhaustion even if another combination
had been possible.
This commit reduces the probability for this event by skipping UL
slots without free USF while calculation the capacity.
Note that the implementation is rather inefficient which will be
fixed by the following commits.
Sponsored-by: On-Waves ehf
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Since currently the algorithm B will only allocate a single UL slot
and will have to stick to it (first common TS), the other possible UL
slots will not be allocated while the reservation is kept.
This commit adds code to update the reserved set of UL slots to only
reserve the single common TS when the UL TBF is allocated.
Interestingly this leads to fewer allocated TBF in some cases due to
USF exhaustion. This will be improved by the following commit "alloc:
Skip common TS without free USF".
Sponsored-by: On-Waves ehf
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Currently al possible UL slots are included in the capacity
calculation which is the base of the slot selection. Nevertheless
UL-only slots will never be used, since only one uplink slot (which
must be a common slot) will be used.
This patch changes the code to only include common slots in the
capacity sum.
Note that this might not be optimal if algorithm B supported
multiple uplink slots.
Sponsored-by: On-Waves ehf
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The current implementation always starts the downlink slot allocation
with the first possible slot, depending on which channels are enabled
and which multislot class is offered by the MS. So in configurations
with many (>4) PDCH, some PDCH are not really used.
The new implementation introduced by this commit differs as follows:
- The reservation mechanism provided by GprsMs is used to avoid
incompatibilities is used in the same way like algo A does. This
basically means, that the allocation is done once when the first
TBF is requested and then used until all TBF have been released.
- All combinations of Rx and Tx slots are checked for compatibility
with the multiscot class. Basically the combination with the most
usable PDCH and the least number of reservations is used.
- Only one UL slots is provided.
- Tta and Tra are checked.
Sponsored-by: On-Waves ehf
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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
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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
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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
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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
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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
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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
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These assertions check for the TBF allocation result before the tbf
object is dereferenced the first time.
Sponsored-by: On-Waves ehf
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When this environment variable is set, the logging level is set to
LOGL_DEBUG to help debugging without putting everything into
AllocTest.err.
Sponsored-by: On-Waves ehf
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This commit adds:
- an assertion to check that count is valid,
- an assertion the verify that tbf_alloc did not fail
- a slots parameter to specify the enabled slots
- additional test invocations with more slots enabled
Sponsored-by: On-Waves ehf
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This test allocates as many as possible UL/DL TBF pairs, shows their
PDCH usage, and checks how many of them has been created
successfully.
Sponsored-by: On-Waves ehf
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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
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Currently the old TBF (either uplink or downlink) is passed around at
TBF allocation mainly to get information about the MS. To implement
more complex allocation algorithms, the MS object itself will be
needed anyway.
This commit replaces the old_tbf arguments by MS object arguments.
Sponsored-by: On-Waves ehf
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This method does not do anything anymore, it's functionality has been
taken over by update_ms.
This commit removes gprs_rlcmac_tbf::update_tlli completely.
Sponsored-by: On-Waves ehf
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Using complex initialiser lists doesn't seem to work well with Debian
Squeeze.
This commit changes the initialisation to use separate assignments
instead.
Fixes: Jenkins #601, #602
Addresses:
CXX LlcTest.o
../../tests/llc/LlcTest.cpp: In function 'void test_llc_meta()':
../../tests/llc/LlcTest.cpp:137: error: expected primary-expression
before '.' token
../../tests/llc/LlcTest.cpp:137: warning: extended initializer
lists only available with -std=c++0x or -std=gnu++0x
Sponsored-by: On-Waves ehf
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This reverts commit a99d95e3afc528829f657e37f0572ac78bf06d4b.
That commit has only removed the warning but not the error.
Sponsored-by: On-Waves ehf
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To support extended initialiser lists some platforms (at least debian
squeeze) require to add -std=c++0x or -std=gnu++0x to CXXFLAGS. While
that option is deprecated on newer platforms (at least gcc 4.8) this
options is still supported on every platform currently in use.
This commit adds -std=gnu++0x to the CXXFLAGS used to compile
LlcTest.cpp.
Sponsored-by: On-Waves ehf
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Currently the receive and expiry timestamps are prepended to the LLC
msgb before it is passed to gprs_llc_queue::enqueue(). Since this meta
information should not be counted as LLC octets, the gprs_llc_queue
needs to known about this (unless the correction was done in the LLC
layer).
This commit moves the meta information storage code into
gprs_llc_queue. The meta data is now stored in the control block
(cb) area of the msgb.
Note that the info pointer that is returned from the dequeue method
is only valid if that method returns a (non-NULL) msgb. It must not
be used after that msgb has been modified or freed.
Sponsored-by: On-Waves ehf
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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
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To get the number of LLC octets that are stored in the queue, this
commit adds a m_queue_octets member along with a octets() method.
This value is updated similarly to m_queue_size on each modifying
method call.
Sponsored-by: On-Waves ehf
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Sponsored-by: On-Waves ehf
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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
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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
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This change lets the test suite fail, so it get its own commit.
Sponsored-by: On-Waves ehf
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Currently only the RSSI value is passed to the upper layers. Other
values like TA and BER which are needed for TA update respectively CS
selection are not propagated.
This commit introduces and passes a struct that contains a set of
measurement values.
Sponsored-by: On-Waves ehf
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This is needed to link programs using clock_gettime and related
functions when compiling with older glibc versions.
This should fix the Jenkins build. Nevertheless fixing this in
configure.ac were probably nicer.
Sponsored-by: On-Waves ehf
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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
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Since more functionality will be moved to the GprsMs class, a pointer
to the current BTS object is added to allow access to configuration
data and other methods.
Sponsored-by: On-Waves ehf
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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
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Currently the MS object is immediately idle when all TBFs are
detached and if no guard is being used. Since the plan is to use the
MS objects to pass information from one TBF to the next one even
across the gap of some seconds of inactivity, a mechanism is needed
to keep the MS objects around for some time.
This commit extends the GprsMs class by a timer that keeps the MS
objects in non-idle state for some time after all TBFs have been
detached. The set_timeout method must be used with a non-zero value
to activate this feature.
Sponsored-by: On-Waves ehf
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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
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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
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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
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Currently the DL TBF's TLLI are not set. This will have to change in
the future, when the m_new_tbf chaining is replaced by the usage of MS
object to group TBFs.
This commit just calls update_ms() on newly created TBFs. This
changes many of the lines written to stderr due to the TLLI change,
but doesn't change other aspects or messages beside creating and
destroying MS objects.
Sponsored-by: On-Waves ehf
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This commit extends get_ms() to really compare the IMSI if it has
been given. Matching by TLLI has a higher precedence than matching by
IMSI.
Ticket: #1674
Sponsored-by: On-Waves ehf
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Currently the IMSI is stored in the TBFs. Since it directly refers to
an MS, it should rather be stored in an MS object.
This patch move the m_imsi field from gprs_rlcmac_tbf to GprsMs,
changes gprs_rlcmac_tbf::imsi() to get the IMSI from the associated
MS object, and adds getter and setter to GprsMs. Before changing the
IMSI of the associated MS object, assign_imsi() checks if there is
already another MS object with the same IMSI and eventually resets
the IMSI of that one. So using update_ms() and assign_imsi() ensures
that there are not two MS object entries is the storage with the
same TLLI or the same IMSI.
Ticket: #1674
Sponsored-by: On-Waves ehf
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Currently the generated IMSI contains blanks due to a missing '0'
flag in the corresponding snprintf statement. In addition, the buffer
is effectively limited to 15 bytes which is shorter than the
generated character sequence, such that the last character of the
IMSI is removed.
This patch fixes both issues. Since snprintf itself will add a
terminating \0 character, the whole buffer can be passed to snprintf.
Sponsored-by: On-Waves ehf
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Currently the m_tlli member in GprsMs is set by the constructor,
circumventing the TLLI confirmation mechanism.
This commit replaces the get_or_create_ms() method by a create_ms()
method which takes the TLLI and the direction (UL or DL) as
parameters to select either set_tlli() or confirm_tlli(). The MS
object is instantiated with TLLI = 0, and therefore GprsMs::tlli() is
extended to return the DL TLLI if both of the other TLLI are not set.
Note that create_ms() will not check whether an MS object with a
matching TLLI is already stored in the list, so it should only be
called after a corresponding get_ms() in general.
Sponsored-by: On-Waves ehf
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Currently the TLLI is stored in each TBF. Since each MS is now
represented by a GprsMs object which takes care of TLLI updating,
and each TBF that has been associated with an TLLI also contains a
reference to a GprsMs object, per TBF TLLI handling is no longer
needed. Keeping all TBF m_tlli members up to date is complex and
doesn't currently work correctly in all circumstances.
This commit removes m_tlli and related members from the TBF class and
the tbf_by_tlli functions from the BTS class.
Ticket: #1674
Sponsored-by: On-Waves ehf
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Debian is using the classic bfd linker and when passing
libosmogb as link dependency it always wants/needs to
resolve the bssgp_prim_cb symbol (which is to be provided
by the application).
Only keep the libosmocore dependency.
Fixes:
lib/libosmogb.so: undefined reference to `bssgp_prim_cb'
collect2: error: ld returned 1 exit status
Makefile:511: recipe for target 'llist/LListTest' failed
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Currently the MS will be searched based on the TLLI in resue_tbf().
Since the MS object is already known in the TBF when the TLLI is set,
it can just be passed to the new TBF.
This commit removes the call to update_ms() and just adds
new_tbf->set_ms(ms()) which will also work as expected if ms() == NULL.
Sponsored-by: On-Waves ehf
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The type of the TBF update_ms() is being called on does not always
reflect whether the TLLI has been signaled by the MS or the SGSN.
This commit adds an additional parameter to tell the method, in which
direction the TLLI has been passed.
Sponsored-by: On-Waves ehf
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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
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Use the MS storage to find a MS object for a given TLLI instead of
searching the TBF lists. The TBFs are then taken from the MS object,
if one has been found. If all TBF might be temporarily detached from
the MS object, a GprsMs::Guard is added to prevent the deletion of
the object, in case another TBF gets attached later on in the scope.
Ticket: #1674
Sponsored-by: On-Waves ehf
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