Various fixes for UE handling, HO doc updates
- On release request, search both attach and connected list to free a UE.
- on DU disconnect, only release the correspnonding UE contexts.
- When no AMF for the UE, auto-release the UE (NGAP would also send an
answer, but better check first)
- implement a "grace period" before the DU/MAC automatically releases a
UE: this is to avoid cases in which (for whatever reason) the UE
release request is not honored by the CU. In order to not fill up UE
contexts unnecessarily, the DU will eventually (after 10s) drop the UE
context
- some clarification in HO tutorial
It might happen that the CU does not answer a release request. In that
case, the MAC would never free the UE context, potentially blocking the
DU. Avoid this by introducing a "grace period" after which a UE context
is automatically freed at the MAC (and RLC), currently at 10s after the
30s UL failure timer.
NR RRC Reject UE
Improvements in procedures to handle RRCReject message both at gNB and
UE. At gNB we send RRC Reject if the UE cannot be given resources to go
into connected mode.
Fix NR reestablishment by implementing the "DRB-suspend" at the MAC.
This means that the during reestablishment, gNB MAC discards received
DRB packets, and does not schedule DRB. Fix a couple of additional
issues in reestablishment. # Please enter a commit message to explain
why this merge is necessary,
For additional information, see
https://gitlab.eurecom.fr/oai/openairinterface5g/-/merge_requests/2668#note_119369
The spCellConfig is to be dropped during reestablishment and to be
applied after reconfiguration. Implement this using the
RRCReconfigurationComplete acknowledgment from the CU to the DU,
applying the spCellConfig if present (which signals a prior
reestablishment). Remove a prior flag that is not needed anymore, and
do not "guess" when is the reconfiguration, because it is now handled in
the case of the ack.
The spCellConfig is not relevant as long as we use a common search space
for DCIs (and the activation of dedicated search space happens after
applying spCellConfig). For PUCCH, there is the PDSCH transmission of
RRCReconfiguration which gets ack'ed in the default PUCCH.
RRCReconfigurationComplete is sent in PUSCH (again through common
search space). In theory, there cannot be another PUCCH before the
application of spCellConfig, as all bearers are still suspended, and
there should not be another SRB1 transmission in the meantime, as only
one RRC transaction can be active at a time.
Co-authored-by: francescomani <email@francescomani.it>
Add a flag for each RB that tracks suspension state. Mark all RBs
(except SRB1) as suspended on reestablishment, and de-suspend on
reconfiguration. Only check RLC status for non-suspended RBs. For UL
data traffic, check that DRB/SRB2 exist (SRB1 should be there as soon as
the UE context exists).
- remove hardcoded values
- adapt gNB RRC code
- adapt gNB MAC code
- adapt physical simulators, where we put the hardcoded values
that were everywhere else before; if there is a need for those
simulators to get configurable values, more work is needed
(but it's doubtful that it is needed)
Fix PDSCH and PUSCH BWP Start and Size when PXSCH is scheduled with a DCI format x_0 in any type of PDCCH common search space
- Fix PDSCH and PUSCH BWP Start and Size when PDSCH/PUSCH is scheduled
with a DCI format x_0 in any type of PDCCH common search space
- Fix resource block assignment information (RIV field) for DCI format
x_0 when scheduling in any type of PDCCH common search space
- rewrite add_UE_to_list() and rewrite remove_UE_from_list() to simplify
list handling
- return pointer from get_new_nr_ue_inst(); it's completely freed by
delete_nr_ue_data()
- have add_new_UE_RA() add UE context to access list; remove with
nr_release_ra_UE()
- have add_connected_nr_ue() only add UE to connected list; to move from
access to connected use transition_ra_connected_nr_ue(); remove with
mac_remove_nr_ue() as previously
- free memory on problems during RA
- add some documentation
- in NSA/HO: check for pre-configured RA process
- there are asserts in all functions to clarify when a UE has RA
Add support for 'dl_min_mcs' and 'ul_min_mcs' configuration parameters
Add support for 'dl_min_mcs' and 'ul_min_mcs' configuration parameters,
they will enforce the gNB scheduler to select always a MCS equal or
above its values
In addition to use a min value for MCS, this MR also enables the testing
of a specific MCS value with COTS UE, by setting
xl_min_mcs = xl_max_mcs
example:
dl_min_mcs: 22
dl_max_mcs: 22
ul_min_mcs: 7
ul_max_mcs: 7
In the example above, the scheduler will use always MCS 22 for downlink
and MCS 7 for uplink.
The aggregation level search order for PDCCH candidates is modified:
- the search starts from desired_agg_level_index, which is a value from 0 to 4
proportial to pdcch_cl_adjust.
- pdcch_cl_adjust is a value between 0 and 1 that indicates PDCCH channel quality
by averaging HARQ DTX rate. A value of 0 means perfect channel, a value o 1 means
impaired channel.
Jaroslava Fiedlerova