Currently the code that creates the MS objects with tbf.cpp is
duplicated.
This commit moves the corresponding code into a new method. Since
there is no TLLI available there, the GprsMsStorage::create_ms method
has been refactored into two variants, one with TLLI/direction and
one without.
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
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
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
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
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
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
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
Currently struct llist_head is used without declaration which
accidently did not produce an error so far.
This commit adds the missing include directive.
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 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
The I_LEVEL values that are obtained now look suspicious. They do not
seem to be contained in messages recorded via gsmtab.
To help debugging this issue, this commit adds related debug messages
that are generated while the encoded values are taken from the
RLC/MAC messages.
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 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
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
The gprs_rlcmac_tbf::name() method is generally used to generate log
messages. To avoid the need for an explicit NULL check for the tbf
and to get a consistent text if it is NULL, this commit adds a
NULL check to the method itself so that it can be called with this ==
NULL.
Fixes: Coverity CID 1304680, 1304681
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 the wrong nibble is masked out, so the conditional
expression always yields true.
Therefore gprs_llc::is_user_data_frame() always returns true. As a
consequence, the low watermark feature of
gprs_rlcmac_dl_tbf::llc_dequeue() is not being used in fact.
This commit fixes the mask value.
Fixes: Coverity CID 1292834, 1292835
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
This commit extends the "show ms" command to display an extended set
of information for a single MS.
The following VTY commands are added:
- show ms tlli TLLI
- show ms imsi IMSI
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
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
This commit adds the following VTY commands to config-pcu:
- cs threshold <0-100> <0-100> Enables adaptive CS selection
- no cs threshold Disables it
The "cs threshold LOW HIGH" command sets the water marks
(cs_adj_lower_limit and cs_adj_upper_limit) used to
decide about switching coding schemes.
Ticket: #1739
Sponsored-by: On-Waves ehf
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
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
This command lists the entries of the ms_store by a line per MS.
Beside TLLI and IMSI, some measurement and state information is
shown.
A ms_list() getter method is added to GprsMsStorage to obtain a list
of the MsGprs objects.
The following VTY command is added to the 'enable' node:
- show ms all
Sponsored-by: On-Waves ehf
Currently the pcu_vty.c doesn't compile with C++. Thus C++ object
cannot be access directly there.
This commit adds a helper C++ file that exports all functions with C
calling conventions and naming to work around that limitation until
the transition of pcu_vty.c is completed.
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
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
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
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
Currently llc.h relies on the structs BTS, timeval, and msgb being
declared before the file is included.
This commit adds forward declaration for these structs, because they
will only be used for pointer types.
Sponsored-by: On-Waves ehf
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
The acc_delay value is computed but not used, resulting in a warning.
This commit adds a logging message it case the function is executed
to make the warning disappear. It also adds a CPP warning to remind
of the incomplete implementation.
Addresses:
sysmo_l1_if.c:226:10: error: variable ‘acc_delay’ set but not used
[-Werror=unused-but-set-variable]
Sponsored-by: On-Waves ehf
Since the timing advance storage has been removed, the TA values are
lost, when the last TBF of a single MS is freed. The TA storage has
at least saved the last 30 TA values. So now in more cases a wrong TA
value can be transmitted to an MS. Note that this also could have
happened before the removal of the storage, especially if more than
30 MS were in use.
This commit changes the default value of ms_idle_sec to 60s which is
higher than default value for T3314 (44s, see TS 24.008, 11.2.2),
after which the SGSN will have to start paging anyway. In that case,
a RACH request will be triggered, that will trigger an update of the
TA value in the PCU.
Sponsored-by: On-Waves ehf
This commit sets the MS timeout when the MS object is created. The
value is taken from the ms_idle_sec field in gprs_rlcmac_bts which
can be changed by the VTY commands shown below.
The following VTY commands are added to the config-pcu node:
- ms-idle-time <1-7200> Set the timeout in seconds
- no ms-idle-time Disable the timeout
Another timer that is related is T3314 (Ready Timer, default 44s, GSM
24.008, 11.2.2) which requires the SGSN to use paging after its
expiry. Longer timeouts can help if adaptive coding scheme selection
is used (not yet implemented). On the other hand, measurement values
(TA, signal quality) can get invalid after some time, especially with
a moving MS. So a value slightly above T3314 is probably a good value
to start with.
Sponsored-by: On-Waves ehf
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
Currently the TA storage stores up to 30 TLLI->TA mappings, if more
entries are created the oldest one is dropped. In theory this can
lead to missing TA information if many MS are present.
This commit removes the TimingAdvance class completely, since the TA
value is now stored in the GprsMs objects.
Note that the GprsMs objects are currently not kept after the TBFs
have detached from them, so the TA values are now kept for a shorter
time than before.
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
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
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
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
Jacob Erlbeck