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.
The OpenBTS socket functions are moved from main to pcu_l1_if.cpp.
New sysmo_l1_if.cpp is introduced. It used special unix socket interface
to connect to sysmo-BTS. This is required to access CCCH/RACH and info
about cell layout. Traffic is also forwarded via this interface, but
it direct access of L1 baseband DSP will be added soon.
In order to handle ready-to-send requests above l1_if, the transmit
queue (for downlink blocks) is moved to gprs_rlcmac.cpp.
The TBF instance additionally holds TRX and TS info, but this is only
a hack currently. TBF instance requires more details about allocated
ressources in the future.
Added functions for TBF allocation, establishment, data transfer and release management.
Modified TBF structure, added list for several LLC PDUs in one TBF.
Added function gprs_rlcmac_tx_llc_pdus() providing transmission of several LLC PDUs in one TBF to MS.
this is probably a historic relict. None of them should be used, and I
cannot see any actual use of them either.
The only non-library code that we link now is libosmo-gb (ns/bssgp),
which soon will be turned into a real library.
Andreas Eversberg
Holger Freyther
Harald Welte