This test will check that we exhaust the available TFIs, so the last
TFI is -16 and then we try to store to that address. It is surprising
that it worked!
Currently single BSN blocks of size 68 (a single unit from MCS-8)
are put into a MCS-6 block with padding according to TS 44.060
Annex J. Unfortunately, these packets are ignored by the E71. This
might be related to the currently incorrect usage of the puncturing
schemes and the RSB bit (the puncturing schemes are not updated and
the RBS flag is never set).
Avoid downgrading from MCS-8 to MCS-6 if there is no second block
available. Send the block twice instead.
Sponsored-by: On-Waves ehf
Currently only one BSN block is encoded in each RLC data message,
even if MSC7-9 are used, which transport two independant (except for a
max BSN delta of 512) BSN blocks. In that case, the same block is
just put twice into the same message.
The current create_dl_acked_block(fn, ts) method handles
block selection (resend, new BSN, dummy block, ...) and restart
handling in one method and is too complex to extend it accordingly.
Therefore this commit move the block selection/creation handling into
a new method (take_next_bsn) which delivers the next BSN along with a
hint, whether it may be combined with another block. In that case,
the function can be called a second time (this time with a valid
previous BSN, that's the one returned by the first call) to get the
second BSN. The real block generation method
create_dl_acked_block(fn, ts, index, index2) is then called with both
BSNs as indices (the second must be -1, if there is only one BSN).
Note that every BSN returned by take_next_bsn should be passed to
create_dl_acked_block to avoid state inconsistencies.
Sponsored-by: On-Waves ehf
Currently the method is hard-coded to support a single BSN only.
MCS-7 to MCS-9 encode 2 data blocks into a single RLC data message.
This commit refactors create_dl_acked_block to process any number
of blocks internally.
Note that this does not extend the parameter list accordingly and
just duplicates the BSN if these MCS are being used.
Sponsored-by: On-Waves ehf
The offsets of the data areas change when padding is used (see TS
44.060, 9.3.2.1 and Annex J for details).
Extend the parameter lists to pass the with_padding flag and use
that information to compute the correct offsets.
Sponsored-by: On-Waves ehf
Return the amount of optional padding bits, which is 6*8 for
MCS-3 and MCS-6 and 0 for all other coding schemes. The padding
is needed the encode 68 byte data blocks (MCS-8) with these schemes.
See TS 44.060, 9.3.2.1 and Annex J for details.
Sponsored-by: On-Waves ehf
Currently the state on the TBF is set to ASSIGN when it is created
and in general changed to FLOW when it is acknowledged by the MS. The
moment when the assignment is really transmitted to the MS (which can
take some time) is not reflected by the state. A TBF can considered
to be valid, when the assignment is received by the MS.
Add the state WAIT_ASSIGN that is entered when the assigment has been
send to the MS (more precisely: when the corresponding RTS has been
processed or the message has been sent to the BTS).
The TBF, its PDCH(s), and its TFI can be assumed to be valid, when the
TBF has a state of WAIT_ASSIGN or higher (assuming that the TBF
starting time has not been set, which is currently only done for SBA,
which are not associated with a TBF).
Note that due to queuing in the BTS there can still be a invalid
time period for immediate assignments, when the request is lingering
in the AGCH or PCH queues.
Sponsored-by: On-Waves ehf
The EGPRS support will need more information to encode the IMMEDIATE
ASSIGMENT. Instead of adding more parameters pass a pointer to the
TBF unless an SBA shall be done (indicated by tbf == NULL). All
values that can be derived from the TBF and are not needed for an SBA
are removed from the parameter list.
Return a negative value on error.
Sponsored-by: On-Waves ehf
Currently the old TFI is always used as ID when a
PACKET DOWNLINK ASSIGNMENT is generated. This fails
if the old TBF has not been fully assigned yet. The
MS will then ignore the PDA.
This commit changes write_packet_downlink_assignment to accept
an additional parameter old_tfi_is_valid and uses the new TBF's
TLLI instead of the olf TFI if that parameter is set to false.
Sponsored-by: On-Waves ehf
Currently the checks for and the actual polling is done in several
places by copy & paste of several lines of code. This hinders changes
of they polling is handled internally and also is likely source of
programming mistakes.
Separate this into a check_polling function, that checks whether
polling is possible and returns the FN and the RRBP to be used in
that case. Otherwise the cause is logged (LOGL_DEBUG) and a negative
error value is returned. There are no other side effect beside the
logging.
If the call is successful, the set_polling method can be used to
actually register the polling.
Extend the encoder functions' parameters lists by an rrbp parameter.
Sponsored-by: On-Waves ehf
Currently tbf->control_ts is used to look up an incoming poll
response. Since that may eventually change, poll timeouts could
theoretically happen in that case.
Store the real poll TS in tbf->poll_ts at all places where
tbf->poll_fn is set. Do not use tbf->control_ts to look up
outstanding polls.
Sponsored-by: On-Waves ehf
Currently existing TBF can be reused after an MS has sent a RACH
request. Since the MS can be or most probably is in packet idle mode
in that case, the TBF are no longer usable even if they share the
PDCHs and the control TS with the new one.
There are occasional freezes where the MS does no longer react to
messages sent on the PACCH.
This change aborts all pending TBFs if a new TBF is or has been
established via RACH.
Sponsored-by: On-Waves ehf
Currently the is a release() function which takes care of
statistics and shutdown of properly finished TBFs, but which
cannot be used for aborted TBFs.
This commit add an abort() method which handles unacked RLC blocks
as lost and doesn't start a release timer. This method will be
invoked by tbf_free() for downlink TBF.
Sponsored-by: On-Waves ehf
Make use of variables, log them to LOGL_DEBUG, and reduce code
duplication.
This should help to narrow down the cause why snd_dl_ass are not
answered by the MS sometimes.
Sponsored-by: On-Waves ehf
Currently the values in the BSSGP RA Cap IE are eventually use
overwrite the 'good' values obtained from the MS earlier.
Use the 'good' values when the are present, which is assumed if
at least one of ms->ms_class() or ms->egprs_ms_class() is set.
Sponsored-by: On-Waves ehf
Currently the window size is fixed to 64 even for EGPRS.
Support dynamic window sizes depending on the number of PDCH. The
WS can be set to b + f * N_PDCH. If the result is not valid according
to TS 44.060, Table 9.1.9.2.1, the value will be corrected to use the
next lower valid value (or 64).
The following VTY commands are added (config-pcu node):
window-size <0-1024> set base (b) value and leave f unchanged
window-size <0-1024> <0-256> set base (b) and factor (f)
Sponsored-by: On-Waves ehf
Currently the plain 'egprs' command enables EGPRS but doesn't prevent
phones from being served in GPRS mode if they do not support EGPRS.
This involves complex frame allocation implementations in dynamic
mode, especially if 8PSK is being used. This is due to the inability
of non-EGPRS phone to decode 8PSK USF and ES/P altogether. Since
polling has a higher priority than USF, collisions will have to be
prevented by the PCU by never using an GPRS USF if it refers to a FN
that is already being used for polling.
This commit just disables mixed usage by ignoring GPRS-only request
if EGPRS is enabled.
The following VTY command (config-pcu node) is changed:
egprs -> egprs only
Sponsored-by: On-Waves ehf
The bitvec RBB is always valid, even when FINAL_ACK_INDICATION is
set. This is done by the ack/nack decoder function which fake a
bitmap starting with V(A) up to V(S)-1 in that case (see
Decoding::handle_final_ack).
Call gprs_rlcmac_dl_tbf::update_window unconditionally and only use
is_final for logging and TBF state changes in
gprs_rlcmac_dl_tbf::rcvd_dl_ack.
Sponsored-by: On-Waves ehf
Currently only GPRS data block encoding is supported.
This commit adds rlc_data_to_dl_append_egprs which does the EGPRS
specific extension and chunk handling. It extends
Encoding::rlc_data_to_dl_append to use that function for MCS coding
schemes.
Sponsored-by: On-Waves ehf
Currently the GPRS data block encoding is applied to every
coding scheme, even if an MCS is selected.
This commit renames the actual encoding function to
rlc_data_to_dl_append_gprs (not exported) and puts
selection code into Encoding::rlc_data_to_dl_append. This
requires an additional cs argument.
Sponsored-by: On-Waves ehf
Currently TBF related tasks (status changes, counter updates,
LLC dummy command insertion) as well as
RLC data block generation are done within create_new_bsn.
The data block creation part has already been copied to
the stateless Encoding::rlc_data_to_dl_append function.
This commit changes create_new_bsn to use the encoder function and
just care about the TBF related stuff.
Since the rlc_data_to_dl_append function has been validated against
the test cases being described in annex B of TS 44.060, this
commit fixes an encoder bug which leads to broken LLC frames in
a special case (see example B.2, the main header's E bit was
erroneously set to 1 in that case). When this happens, the LLC frame
will get discarded after reassembly, so that TCP will have to
retransmit the lost packet.
Sponsored-by: On-Waves ehf
This function appends a single chunk to an RLC downlink data block.
The implementation is basically taken from the
gprs_rlcmac_dl_tbf::create_new_bsn method without the TBF related
functionality and any side effects.
Note that it still only supports GRPS.
Sponsored-by: On-Waves ehf
This commit removes the use of struct rlc_dl_header from
gprs_rlcmac_dl_tbf::create_dl_acked_block and
gprs_rlcmac_dl_tbf::create_new_bsn. Instead of patching the
data area directly, the RLC block encoding functions are used.
Note that the data unit encoding is still hard-coded to GPRS in
create_new_bsn, so using MCS 1-4 (albeit being supported by the
encoder) will not work yet.
Sponsored-by: On-Waves ehf
Currently the (GPRS) RLC block encoding is done by setting the
header fields directly in gprs_rlcmac_dl_tbf::create_new_bsn.
This is much more complex with EGPRS, since the data fields are
not byte aligned, the header formats depend on the header type,
and the mapping of bits to bytes is LSB first.
This commit adds Encoding::rlc_write_dl_data_header which writes
the header according to the given gprs_rlc_data_header structure.
Encoding::rlc_copy_from_aligned_buffer is also added to copy
byte sequences into the message.
Note that the actual encoding of data units is not yet present.
Sponsored-by: On-Waves ehf
Add the functions gprs_rlc_data_info_init_dl/ul which initialise a
gprs_rlc_data_info structure depending on the coding scheme. The
fields num_data_blocks, data_offs_bits, cs, and the data_blocks are
valid after this call. The other fields are set to 0.
The data blocks are initialised to the correct data_len, e == 1
(no extension header field), cv == 15 (not a final block). The other
data block fields are set to 0.
The gprs_rlc_data_block_info can also be initialised separately
by using the gprs_rlc_data_block_info_init function.
Sponsored-by: On-Waves ehf
Currently the RLC message length that is obtained from the DSP is
reduced by 1 if the last byte of the buffer includes spare bits.
While this worked well with GPRS, these bits are being used to
encode RLC blocks in EGPRS mode. Thus this last byte must not be
chopped off. The functionality of the code is not affected by this,
since the modified length value is not used.
This commit adds GprsCodingScheme::usedSizeDL/UL to return
the number of bytes needed to encode the message block. If there are
single bits at the end that are to be used (EGPRS), the functions
return the number of full bytes plus 1 (which is the buffer size
reported by the DSP and returned by sizeUL/sizeDL). The commit also
removes the len parameter from rcv_data_block_acknowledged.
Sponsored-by: On-Waves ehf
These struct names are more specific than necessary. They are used
for GPRS (uplink) already. In downlink direction, only a few fields
will be added to the header struct. Add addition,
gprs_rlc_ul_header_egprs does not map directly to an encoded
header, like many other 'header' structs do.
Change the names to fit both modes and both directions:
gprs_rlc_ul_header_egprs -> gprs_rlc_data_info
gprs_rlc_ul_data_block_info -> gprs_rlc_data_block_info
Sponsored-by: On-Waves ehf
Currently GPRS is always used for downlink, which violates TS 44.060
(concurrent TBF must have the same mode).
Enable EGPRS mode for downlink if the EGPRS MS class is != 0 and
EGRPS has been enabled.
Note that EGPRS Ack/Nack handling is not yet implemented, so enabling
EGPRS will not work still. But we will now get EGPRS DL ACK/NACK
messages now from the MS.
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
LListHead does basically the same like llist_pods, but more C++ish
and with type safety.
This commit turns the former list field of gprs_rlcmac_tbf into a
private field, provides accessors, moves the related code from
pcu_vty.c to pcu_vty_functions.cpp, and removes the llist_pods
type and related code.
Sponsored-by: On-Waves ehf
Currently the gprs_rlc_dl_window and gprs_rlc_ul_window do not have
constructors, but need to get initialized explicitly.
This commit adds constructors to both classes and removes explicit
external initialization code.
Sponsored-by: On-Waves ehf
Currently GPRS is handled by the old code path while EGPRS already
uses the unified functions. The rcv_block_egprs is basically not
specific to EGPRS and just needs minor modifications to handle GPRS.
This commit turns gprs_rlcmac_pdch::rcv_block_egprs into a unified
rcv_data_block method and uses it for GPRS, too.
Note that the logging messages of the new parser are different.
Sponsored-by: On-Waves ehf
Currently gprs_rlcmac_tbf::extract_tlli takes care of decoding and
the TBF update. These are really different things and doing the
decoding in extract_tlli makes EGPRS support more complex.
This commit moves the TBF state related part into a new method
gprs_rlcmac_tbf::set_tlli_from_ul.
Sponsored-by: On-Waves ehf
Currently gprs_rlc_ul_window::receive_bsn calls raise_v_q and returns
the number of RLC data blocks that can be taken from the queue. This
does not fit the EGPRS feature to put 2 independant data blocks in a
single RLC block.
This commit removes raise_v_q from receive_bsn, hence it must be
called explicitely to get the number of processable data blocks.
Sponsored-by: On-Waves ehf
This commit adds the methods maxDataBlockBytes and numDataBlocks
which provide information about the data areas within RLC messages.
In these areas, the extension bytes, TLLI, and the LLC data are
stored.
Sponsored-by: On-Waves ehf
The header type depends on the coding scheme, for GPRS there is a
single data header type per direction, for EGPRS there are 3 per
direction. In addition, control block header types are used with CS-1
only, so there is one of the per direction altogether for GRPS and
EGPRS.
This commit adds the header type enum and two methods headerTypeData
and headerTypeControl.
Sponsored-by: On-Waves ehf
Currently the block size is mapped by a switch statement to strip
extra bits that are not used for RLC blocks. That information is
already available via the GprsCodingScheme class.
This commit moves the CS/MCS detection to the rcv_block message and
passes the cs object via rcv_block_gprs, where the length gets
adjusted, to gprs_rlcmac_pdch::rcv_data_block_acknowledged. There the
switch statement is removed.
Note that the TbfTest.err changes due to an additional log message.
Sponsored-by: On-Waves ehf
The multislot (MS) class and the EGPRS MS class can also be passed
via BSSGP in an MS Radio Access Capability element which can
optionally be contained in a DL-UNITDATA PDU. While this case is fully
supported for GPRS, the EGPRS MS class in BSSGP messages is ignored.
This commit extends gprs_rlcmac_dl_tbf::handle to pass the EGPRS MS
class, too.
Note, that the EGPRS class is not yet taken from the CSN.1 RA
capability and is always set to 0. Note also, that append_data
still uses ms_class only.
Sponsored-by: On-Waves ehf
The leak rate sent to the SGSN does not reflect the current CS level,
lost frames, and control message overhead. So the SGSN cannot do
proper queue control under non-optimal conditions.
This commit computes the leak rate for the last flow control interval
by computing the maximum theoretical leak rate and basically
substracting control blocks, nacked blocks, and reduced block sizes
due to CS downgrade. By using this approach, the value will by more
stable on low load, where the value will tend to be near the value
derived from the configuration. On full load the transmitted value is
completely derived from the measurements.
Note that the MS default values are no adapted to the adapted BVC
leak rate, since a single MS which has a lower link quality would
otherwise be reducing the rate of another MS with good radio
conditions, which would not make much sense if they did not share any
PDCH.
Sponsored-by: On-Waves ehf
Currently an existing DL TBF can get lost in the process of
establishing an UL TBF via RACH. This can lead to stalled connections
until the network sends more LLC frames.
This commit adds a check for a non-empty LLC queue after the UL TBF
has been established to rcv_control_ack (GPRS_RLCMAC_UL_ASS_WAIT_ACK
path) to eventually establish a new DL TBF on the UL TBF's PACCH.
Sponsored-by: On-Waves ehf
Holger Hans Peter Freyther