The slots are choosen in a way that later selection of slots for
concurrent TBFs will have the same downlink/uplink control channel
(PACCH).
This is required for polling acknowledge of new TBF assignment on PACCH.
The MS will always have the same PACCH uplink slot while beeing in packet
transfer mode.
Original code: c7e7f6868b
(The code was committed earlier, but got lost somehow.)
I added IMSI, so the paging request is sent in correct paging group.
Also I excluded rest octets from pseudo length.
It is tested and it work.
Some MS will leave packet transfer mode, if TAI is given, but no timing
advance control messages are sent on PTCCH. This could results in
permanent loss of larger packets.
It is essential to initialize the first_fin_ack variable.
Also it is essential not to free TBF, in case the final ack is not
received, but all frames have been acked. In this special case, we resend
the final block again and again (and poll), until we receive the final
ack.
It is quite essential. It shows how TBFs are related and helps to estimate
states and timers (timeouts) of the MS.
In order to use it, it must be defined by a switch at gprs_rlcmac.h.
Generic improvements to the csn.1 dissector include:
• Added a flag to the type descriptor structure so that any type can (potentially) flagged as xxx_OR_NULL. This was specifically needed for UINT_OR_NULL for the ms capabilities struct.
• Changed the CSN_SERIALIZE so that the length of the length field can be specified.
• For CSN_NEXT_EXIST removed the requirement that the next type be CSN_END, to allow truncation of multiple IEs.
• For CSN_LEFT_ALIGNED_VAR_BITMAP corrected the handling of bit_offset.
• Added a new type CSN_PADDING_BITS to make inspection of padding bits more convenient.
• Improved the CSN_RECURSIVE_TARRAY_1 to show the array index.
Improvements to the gsm_rlcmac dissector include:
• Rework the definition of EGPRS Ack/Nack Description so that the length IE (and absence thereof) is handled correctly.
• Added Padding Bits definitions to all PDUs
• Change the Multislot_capability_t and Content_t definitions to allow truncation at any IE
In this case the mobile has lost existing flows, so it make sense to free
them. The TFI(s) can be re-used immidiately, because they are not
associated by MS anymore.
Be sure to use always two bytes of length information for DL-UNITDATA,
even if the length of LLC data is less than 128 bytes. This way the data
has always the same offset from a 32 bit boundary.
This is required, since we may change slot allocation. In case of a
change, we do not want to be unable to change, if the same TFI on one of
the other slots is already in use by a different TBF (having same TFI, but
on different slot).
It is mandatory to support it because MS may request a single block.
In this case the network must assign a single block.
It is possible to force single block allocation for all uplink requests
on RACH. (VTY option)
Both flags can be used to determine wether assignment must be sent on PCH
or on AGCH. Before contention resolution is done, mobile will ignore
downlink assinment. When final uplink acknowledge was sent, the mobile
will go back to PCH after reception of akcnowledge.
This is required because uplink assignment (PACCH) is done on a request
by mobile, so the mobile expects that it get this assignment in return.
After that we may assign downlink.
If the mobile misses assignment, it changes back to idle mode. In this
case we must kill the pending downlink TBF, because it is not used by
mobile and we can assign a new downlink TBF for new downlink data.
(We may not have two downlink TBF with same TLLI!)
If lifetime expires of queued LLC frames, they are discarded. The number
of discarded frames and the sum of their octets are reported to SGSN
via LLC-DISCARDED message.
The lifetime can be overridden via VTY. The value can be centi-seconds
or "infinite".
In order to do downlink assignment during uplink TBF, the content
resolution must be completed. It is completed when the first Packet
Uplink Ack/Nack message is transmitted to the mobile.
It turned out that the final ack flag may not be set, but all packets
have been acknowledged. This patch will finish transfer in case all
blocks are acknowledged.
The slot must be the control channel TS, which is selected by the
allocation algorithm. The MS must be able to respond at this TS.
The counter to trigger polling is incremented until polling has to be
performed. Then the counter stops. When the transmission of data block is
requested on control channel TS, the counter is reset. The counter-value
is also used to poll immediately when the transmission has finished.
In order to send control blocks to MS and receive control blocks from MS
(polling), it is required to select one timeslot that the MS must be
able to send and receive. The allocation algorithm must take care of
selecting that slot.
The new data structure is required to define slot/TFI assigment for MS
with multislot capability.
Now there are two lists for TBFs: uplink and downlink. It is possible to
have different TBFs with same TFI in the same direction, as long as they
are assigned on different timeslots.
See tbf.txt for description.
Note: This does not implement any multislot support. It defines the new
data structure. Currently only the first slot is assigned.
The signal handler will end the main loop, so clean exit is performed.
The allocated memory is dumped in order to detect memory leaks.
All talloc functions use tall_pcu_ctx context instead of NULL, to track
memory leaks.
Merge is based on jolly_new branch with two modifications.
1. Modified PCU L1 interface.
pcu_l1_if.cpp - common functions for tx and rx messages on L1 interface.
sysmo_sock.cpp - SYSMO-PCU socket functions.
openbts_sock.cpp - OpenBTS-PCU socket functions.
pcuif_proto.h - L1 interface's primitives.
2. Modified encoding of RLC/MAC Control messages, now we use structures and encode_gsm_rlcmac_downlink() function for encode control blocks (without hand-coding).
Only when using LOGL_DEBUG, every detailled information is displayed.
When using LOGL_INFO, a summary of the process is displayed.
When using LOGL_NOTICE, only errors and warnings like timeouts
or invalid received informations are displayed.
When using LOGL_ERROR, only local error like software errorss are
displayed.
The pseudo length may not include the rest-octets, so it stays compatible
to non-GPRS phones.
At pcu_l1_if.c (OpenBTS) no pseudo length is given, so the frame is
only 22 bytes long. I could not test if it works.
The hack for resetting BSSGP instance is removed and now performed
whenever the NS state changes to UNBLOCKED.
The BSSGP instance is now created only once, as it should be.
Received STATUS messages are ignored as they should be.
The creation and destruction of BSSGP/NS instances is now handled by
layer 1 interface alone.
The option added is required to change PLMN that is announced to SGSN.
This allows BTS to have a different PLMN.
(Usefull for roaming in conjunction with simlock.)
These informations provide RAI, timers, counters and other attributes to
the BSSGP and RLC/MAC processes.
The attributes are stored in gprs_rlcmac_bts global structure.
Added functions:
- gprs_bssgp_pcu_rx_paging_ps() for handling paging message from BSSGP;
- write_paging_request() for writing paging request message;
- gprs_rlcmac_paging_request() and pcu_l1if_tx_pch() for sending paging request message to BTS.
It uses history buffer and sends ack/nack control messages about received
blocks. It defragments the blocks and forwards them to upper layer. It
does content resolution and ignores other MS. It sends final ACK after
all blocks have been sucessfully received. Timers are used to detect
loss of uplink, and repeat lost final ACK.
The scheduler is triggered at ready-to-send-requesst. It schedules
control blocks, data block and dummy blocks, depending on priority.
It provides upstream ressource by setting USF. The ressources are
assigned, if required. The ressources are dispatched round-robin.
In case of polling, the upstream ressource is given to MS at the
time it will respond to polling request.