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The confirm_tlli method does not handle TLLI clashes in the MS
storage.
This commit changes gprs_rlcmac_dl_tbf::handle() to use update_ms
instead.
Sponsored-by: On-Waves ehf
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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
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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
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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
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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
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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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Since set_ms() is caled on the new DL TBF, the old DL TBF loses the
reference to the MS object. This will lead to a segfault, when
update() is called in reuse_tbf().
This commit adds an optional GprsMs* parameter to update() and uses it
for the slot allocation.
This fixes a TbfTest crash that would otherwise occur after applying
the next commit.
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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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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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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This change lets the test suite fail, so it get its own commit.
Sponsored-by: On-Waves ehf
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Currently the CS level gets changed quickly if single RLC/MAC blocks
are sent (e.g. LLC dummy commands), since the rate is either 0% or
100%.
This commit ignores measurements which are based on a single block
only.
Sponsored-by: On-Waves ehf
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To help with the debugging, optimisation, and understanding of this
method, this commit adds an info string containing a flag character per
RLC/MAC data block in the current window.
Note that the blocks are shown in reversed order (highest BSN first)
in comparison to other logging output.
Sponsored-by: On-Waves ehf
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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
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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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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 enqueued DL LLC messages which have not yet passed to
RLC/MAC encoding are eventually copied from one TBF to the next one
(see gprs_rlcmac_dl_tbf::reuse_tbf). Since the enqueued LLC messages
are related to a specific MS, they should be stored at that layer.
This commit moves the gprs_llc_queue object to GprsMs and changes the
TBF's accessor methods accordingly. The LLC copying code is removed
from gprs_rlcmac_dl_tbf::reuse_tbf().
Sponsored-by: On-Waves ehf
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Currently the gprs_llc class handles both LLC queueing and the
partition into smaller pieces for RLC/MAC encapsulation. This hinders
the separation of TBF and MS related data, since LLC queueing belongs
to the MS related code while the RLC/MAC encoding/decoding belongs to
the TBF layer.
This commits takes the LLC queueing related methods and members and
puts them into a new class gprs_llc_queue. It puts the queueing
object into gprs_rlcmac_tbf and adds accessor functions. The
implementation in tbf.cpp and tbf_dl.cpp is adapted accordingly.
Ticket: #1674
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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Currently the BTS::trigger_dl_ass() method assigns the IMSI to the MS
object. This should be (and is already) done earlier where the MS
object is retrieved/created.
This commit removes the corresponding code along with the 'imsi'
parameter from trigger_dl_ass.
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 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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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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This commit adds MS object creation and cleanup to the TBF related
code. MS objects are created when a TBF that has been "anonymous" so
far gets associated with a TLLI. When a TBF is replaced by another,
the old TBF is detached and the new one is attached to the MS. When
all TBFs have been detached, the MS object gets deleted.
The TBF related code should not call attach_tbf/detach_tbf directly
but use set_ms instead to make sure, that the references are updated
properly. GprsMs::detach_tbf also calls set_ms(NULL) on the detached
TBF object.
The MS object is not really used yet, the focus is still on object
creation, TBF association, and cleanup.
Ticket: #1674
Sponsored-by: On-Waves ehf
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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
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Currently this function which increments the corresponding counter is
just called in gprs_llc::clear(). It is not called on places where
LLC DISCARDED messages are sent.
This commit adds calls to llc_dropped_frame() at these places.
Sponsored-by: On-Waves ehf
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Currently the value -1 is assigned twice to m_last_dl_drained_fn
within append_data().
This commit removes the first of these assigments.
Sponsored-by: On-Waves ehf
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Currently the PCU silently discard LLC frames from the SGSN if a
DL TBF cannot be allocated.
This commit changes tbf_new_dl_assignment and reuse_tbf to send an
LLC discarded message to the SGSN in this case.
Ticket: #607
Sponsored-by: On-Waves ehf
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If the protocol layers above LLC (e.g. TCP) need an acknowledgement
to continue, it can take up to 400ms (single TS) until the MS is
polled for Ack/Nack which it can use to request an uplink TBF
quickly. The 400ms result from requesting an DL Ack/Nack every 20 RLC
blocks until all pending LLC frames have been sent.
Especially TCP's slow start mechanism can lead to a high delay at the
start of the connection, since the sender will eventually stop after
having sent the first packets (up to 4 (RFC2581) or 10 (RFC6928)).
This commit modifies append_data() to (re-)start
a timer every time it handles an LLC packet and to request an
Ack/Nack every time it expires. So if the server ceases to send IP
packets, the MS is polled in the assumption, that the server is
waiting for an ACK.
The following VTY commands are added (pcu node):
- queue idle-ack-delay <1-65535> timeout in centiseconds
- no queue idle-ack-delay disable this feature (default)
A sensible value is 10 (100ms) that at gave promising results when
testing locally.
Sponsored-by: On-Waves ehf
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Currently single LLC blocks are discarded when the PDU lifetime
expires. If an IP packet has been fragmented either on the IP or on
the LLC layer and is therefore distributed over several LLC frames,
the kept fragments are transmitted and then discarded by the MS
because of the missing PDU. This can cause massive IP packet loss
when there are many fragmented packets (e.g. when trying 'ping
-s1800' or if the GGSN chops downlink IP packets into several SNDCP
packets).
On the other hand, discarding too many packets might disturb the
congestion handling of TCP. Dropping plain TCP ACKs might also hinder
flow control and congestion avoidance.
This commit adds a hysteresis algorithm to the LLC discard loop. If
an LLC message's age reaches the high water mark, further message's
with an age above the low water mark are discarded, too. This is
aborted, if a GMM, a non-UI, or a small message is detected. In
these cases, that message is kept.
The following VTY commands are added (pcu config node):
- queue hysteresis <1-65535> set the difference between high
(lifetime) and low watermark in
centiseconds
- no queue hysteresis disable this feature (default)
Since the SGSN will most probably send all fragments of a single
N-PDU without much delay between them, a value slightly above the
average transmission delay jitter between SGSN and PCU is probably a
sensible value to discard all fragments of a single IP packet.
This is an experimental feature that might be replaced by more
advanced means of active queue management in the future.
Sponsored-by: On-Waves ehf
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If an MS wants to open a new UL TBF, it can either use (P)RACH or
request one in a Ack/Nack message for a DL TBF (PACCH). When a TBF
becomes idle (LCC queue is empty but the TBF is kept open), there
aren't any Ack/Nack requests that can be used by the MS to ask for an
UL TBF, therefore it has to use the RACH. This leads to many RACH
requests even for a single HTTP transaction, so it takes some time to
retrieve even a simple web page.
This commit modifies the scheduler to regularly send Ack/Nack
requests on idle DL TBFs. It does so by extending the priority based
scheduling algorithm to have 5 priority levels (highest priority
first):
- Control block is pending
- High age (100%) threshold reached (-> request Ack/Nack)
- Data is waiting or there are pending Nacks
- Low age (200ms) threshold reached (-> request Ack/Nack)
- Pending Nacks that have been resent already
- None of the above (-> send DL dummy control block)
The 'age' refers to the time since since the last control block has
been sent on the TBF. This high age threshold is set to
dl-tbf-idle-time or to 50% of T3190 (whichever is smaller), aiming
for at least a poll (and TBF shutdown) after the TBF has expired and
to safely prevent expiry of T3190. So if dl-tbf-idle-time > 200ms,
there will be a poll every 200ms and a final poll after
dl-tbf-idle-time. On high load, the interval between polls can get
higher, but the 'high age' poll should be in place.
This commit implements the scheduling with respect to GSM 44.060,
9.3.1a ("Delayed release of downlink TBF").
Ticket: #556
Sponsored-by: On-Waves ehf
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Currently a lot of LLC dummy commands will be generated while waiting
for an ACK for the DL TBF, even if there are blocks that could be
resent instead.
This patch modifies create_dl_acked_block to only call
create_new_bsn() if there is unsent LLC data or m_window is empty.
If the TBF is in state FLOW, no unsent LLC data is left, but there
are blocks left in m_window, those are resent instead.
Sponsored-by: On-Waves ehf
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Currently a DL TBF is immediately closed, when the LLC queue is
drained. This will lead to a new DL assignment if data is received
afterwards. In addition, it is not possible to keep the PACCH open
to poll the MS for UL establishment requests there.
GSM 44.060, 9.3.1a suggests to delay the release of an inactive TBF
for some time (max 5s).
This commit mainly changes create_new_bsn() to send LLC dummy
commands as filler if no LLC data is available until keep_open()
returns false. The keep_open() functions returns true unless a
configurable time has passed after the LLC data store drained. By
default, that time is not set which causes keep_open() to always
return false, so that delayed release is effectively disabled.
The following VTY commands are added:
- dl-tbf-idle-time <1-5000> to set the delay in ms
- no dl-tbf-idle-time to disable delayed release
Ticket: #556
Sponsored-by: On-Waves ehf
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If a BSN is going to be created but there is no frame stored in
m_llc, an empty LLC message would be created. This shouldn't happen
currently, but this will be a common case, when delayed TBF release
is implemented.
This commit changes create_new_bsn() to create an LLC dummy
command in that case and to put it into the frame buffer.
Sponsored-by: On-Waves ehf
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Currently if append_data() is used when there is no LLC data in the DL TBF,
it will either call reuse_tbf() which in turn will call put_frame(),
or it will append the LLC message to the queue, even if the queue and
the frame buffer are empty. This only happens with the test case so
far, but this would change when idle DL TBFs are kept open for some
time. It results in empty LLC message being sent to the MS (see log
below).
This commit changes append_data to check for this case and to
eventually use put_frame() instead of appending the LLC data to the
queue.
Addresses:
TBF(TFI=0 TLLI=0x00000000 DIR=DL STATE=FLOW) downlink (V(A)==0 ..
V(S)==0)
- Sending new block at BSN 0
-- Chunk with length 0 is less than remaining space (20): add length
header to to delimit LLC frame
Complete DL frame for TBF(TFI=0 TLLI=0x00000000 DIR=DL STATE=FLOW)len=0
- Dequeue next LLC for TBF(TFI=0 TLLI=0x00000000 DIR=DL STATE=FLOW)
(len=200)
Sponsored-by: On-Waves ehf
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This functions calculates the number of frames that have passed since
the last DL poll (RRBP flag set) has been sent. It returns a value
less than zero (fn_now - fn_sched) if the block has been scheduled but
not yet sent.
If the function is called before the first data block has been sent
it will return -1.
If the function is called before the first DL poll is sent, it
returns the number of frames since the first data block has been
sent.
Sponsored-by: On-Waves ehf
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Some properties of a DL TBF are explicitly calculated within modules
using DL TBFs.
This commit introduces the methods need_control_ts(), have_data(),
is_control_ts() to hide internals of the DL TBF implementation.
Sponsored-by: On-Waves ehf
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Turn the big nested if statement into a sequence of smaller ones. The
call to create_new_bsn is moved upwards.
Sponsored-by: On-Waves ehf
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Currently the DL Ack/Nack is not requested, if the last chunk of the
final LLC frame in the TBF fits exactly into the remaining space of
the RLC block. It is also not requested, if the RRBP flag cannot be
set due to scheduling issues (single block allocation, polling
already pending for this TBF, ...). So up to POLL_ACK_AFTER_FRAMES
(20) RLC data blocks will have to be resent, before requesting the
Ack/Nack will be retried.
This commit removes the first_fin_ack parameter of
create_dl_acked_block entirely and adds a request_dl_ack() method
that should be called, when the TBF's state changes to FINISHED. This
request will be reset, when the block has been scheduled
successfully. Since the first_fin_ack hasn't been set if chunk ==
space, calling request_dl_ack() on both places in create_new_bsn()
when the state is changed to FINISHED will also fix the first issue
described above.
Note that DL scheduling might not be fair concerning access to
first_ts when multiple TS are used for a TBF. In theory, a TBF might
never get access to first_ts in the worst case.
Sponsored-by: On-Waves ehf
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Currently two DL TBF objects with the same TLLI exist after reuse_tbf
which make the result of tbf_by_tlli undefined. This leads to several
DL TBFs belonging to the same TLLI.
This commit extends tbf_by_tlli to check the m_tlli_valid flag for
DL, too. That flag is set to 0 in reuse_tbf to mark the 'old' DL TBF
as invalid after its LLC data has been copied to the new one.
Sponsored-by: On-Waves ehf
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Remove unused log argument (cnp bug) and unused variable
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If the PCU didn't receive the downlink ack/nack when it was polled there
is no reason to assume it will arrive at a later time. In that case
N3105 is already increased, but the next block sent should have a valid
RRBP set as well to poll again.
This can happen if either the BSN with the valid RRBP gets lost on the
downlink or the DL ACK/NACK gets lost on the uplink path.
Ticket: SYS#382
Sponsored-by: On-Waves ehf
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There are a couple of possibilities where one TBF is used to assign a
new one:
1. Assign a DL TBF from a UL TBF
2. Assign a UL TBF from a DL TBF
3. Assign a DL TBF from a DL TBF which is in wait-release state (T3193 is
running)
In these cases the assignment is sent on the existing TBF and triggers
the assignement of the new TBF (with different TFI/direction).
The current code detects these situations by looking at dl/ul_ass_state
and then chosing the TBF with the opposite direction (DL/UL) that has
the same TLLI. This does not work in the case 3 above where a new DL TBF
is triggered for a DL TBF. The current code reuses the old TBF (and
TFI), but this violates the spec.
This patch introduces a m_new_tbf member which is set to the new TBF to
be assigned. When receiving a control ack the code looks up the
n_new_tbf member of the tbf that requested the control ack and completes
the ul/dl assignment. If the old TBF was in the wait release state
(T3193 is running) it is released.
From 3GPP TS 04.60 9.3.2.6:
"""
If the network has received the PACKET DOWNLINK ACK/NACK message with
the Final Ack Indicator bit set to '1' and has new data to transmit for
the mobile station, the network may establish a new downlink TBF for the
mobile station by sending the PACKET DOWNLINK ASSIGNMENT or PACKET
TIMESLOT RECONFIGURE message with the Control Ack bit set to '1' on
PACCH. In case the network establishes a new downlink TBF for the mobile
station, the network shall stop timer T3193.
"""
reuse_tbf() is modified to allocate a new TBF with a new TFI and trigger
a dl assignment for that TBF on the old TBF. All pending data is moved
to the new TBF.
Ticket: SYS#382
Sponsored-by: On-Waves ehf
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tbf_ul.cpp for UL TBF methods
tbf_dl.cpp for DL TBF methods
This commit contains no code changes.
Ticket: SYS#389
Sponsored by: On-Waves ehf
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