- FAPI structures not to be used as config_req at MAC since that FAPI is
just for communication between MAC and PHY
- additional frame_type member added to the FAPI struct
In FDD mode, the UE_mode switches to PUSCH mode before the initial TA value was applied.
Because of this, the ta_command was misinterpreted.
Fix this by adding 31 to the initial TA comamnd and handle it the same as TA updates.
Implement data transfer (38.331 5.2):
- transmit operation (in nr_pdcp_entity_recv_sdu)
- receive operation (in nr_pdcp_entity_recv_pdu)
- t-Reordering expiration
To keep track of time the function nr_pdcp_wakeup_timer_thread has been
added and is called by the gNB's MAC scheduler via nr_pdcp_tick.
(The UE has not been modified.)
A thread has been introduced to set time of all the existing PDCP
entities in the system. This probably does not scale well with many
PDCP entities (many UEs connected to the gNB). To be changed at some
point when needed. Hopefully, with a few UEs this mechanism won't be
too problematic (ie. won't cause realtime problems).
The problem with time in PDCP is that SDUs are kept if some are
missing, to do reordering. A timer is started and when it expires
we have to transmit the SDUs even if some are still missing. We
want to do that as soon as possible. So we have to check timers
often (every millisecond).
In RLC the time is set when there is some activity (SDU or PDU
received). In PDCP we cannot wait for this kind of activity. We
would keep packets longer than necessary, which may disturb
upper layers (think: TCP). That is why we introduced the thread,
as a simple mechanism to keep packets no longer than necessary.
The locking done by this thread may create realtime issues.
The whole logic of time keeping can be changed later if it turns
out that it is not efficient.
The functions dealing with DRB AM have been removed. All the types
of PDCP entities (DRB AM, DRB UM, SRB) use the same mechanism for
transmit and receive operations. So the code has been made common
for all those types.
We don't deal with:
- entity re-establishment, entity release or entity suspend
- SDU discard (the timer is present but not used)
- status reporting
- data recovery
- data volume calculation
- header compression / decompression
There is no plan to implement those features in a near future.
Integrity protection is not done yet, and will be implemented soon.
1) Only count new transmission as scheduled bytes (which is then
compared against the BSR)
2) When subtracting scheduled bytes after successful reception, subtract
TBsize from correct HARQ process
- scheduled_response was called regardless of the UL config in the PRACH slot
this was leading to wrong behaviour since it was interfering with the
UL config of PUSCH
- a new section in the configuration file to select security algorithms,
with new code to deal with it
- cleanup CG-ConfigInfo: specs seem to indicate that we must not
add mcg_RB_Config; the gNB has to deal with that
- as a consequence, modify fill_default_rbconfig() that is called in
every cases and needs security and bearer parameters
The new section in the configuration file looks like:
security = {
# preferred ciphering algorithms
# the first one of the list that an UE supports in chosen
# valid values: nea0, nea1, nea2, nea3
ciphering_algorithms = ( "nea0", "nea2" );
# preferred integrity algorithms
# the first one of the list that an UE supports in chosen
# valid values: nia0, nia1, nia2, nia3
integrity_algorithms = ( "nia0" );
};
The code is forced to use nea2, no matter what the UE supports.
After 2^18 PDCP packets, it will fail to work (we don't use HFN yet).
These limitations will be fixed in later commits.
The existing security function was not reused, because it does too
much memory allocation and initializes the security context at each
ciphering. So here comes nr_pdcp_security_nea2_cipher(). And also
the ciphering is done inplace. To be changed if necessary.
* add the RA process to handle to command parameters
* Do not create the RAR_pdu into an intermediate array, but directly
into the nFAPI TX_req
* Slightly restructure nr_generate_Msg2() to first make AssertFatal()
checks, then proceed allocating
Remi Hardy