N2 handover
This MR introduces full support for N2 handover, covering handover
decision, preparation, execution, and notification between source and
target NG-RAN nodes.
Key features:
1. Handover Decision & Preparation:
- Implement N2 handover decision based on UE measurement reports.
- Generate the Handover Preparation Information message, including
RRCReconfiguration.
- Send Handover Required message from the source NG-RAN to the AMF.
2. Handover Execution:
- Decode and handle the Handover Request on the target NG-RAN.
- Process the Handover Command on the source gNB, triggering
RRCReconfiguration.
- Initiate Handover Notify after successful completion.
3 NGAP & RRC Enhancements:
- Implement NGAP encoding/decoding functions for Handover Required,
Handover Request, Handover Command, Handover Failure, and Handover
Notify (3GPP TS 38.413).
- Adds NG-RAN Status Transfer support (UL/DL) for PDCP COUNT
preservation during mobility:
- support for NGAP Uplink and Downlink RAN Status Transfer messages
(TS 38.413 §9.2.3.13-14) to enable proper PDCP COUNT value
transfer during handover or recovery: NGAP encoding/decoding for
RAN Status Transfer, PDCP helpers to extract and apply COUNT (HFN
+ SN) per DRB. This aligns with TS 38.300 §9.2.3.2.1 and TS 23.502
§4.9.1.3.3, ensuring PDCP status preservation in AM.
4. Testing:
- Introduce a Telnet command to manually trigger N2 handover using UE
ID and neighbor PCI.
- Add configuration file for testing N2 handover with a target gNB.
Upon reception of NG RAN Status at the target CU-CP, send PDCP Status
via E1 Bearer Context Modification to the target CU-UP and update PDCP Count
upon reception of the message.
For the sake of simplicity, re-used and extended legacy e1_send_bearer_updates.
Further refactoring is not addressed in this commit.
* Check presence of PDCP Status Requested in Bearer Context Modification Request
* Fetch PDCP Status from PDCP entity and fill in the Bearer Context Modification Response
* Introduced nr_pdcp_count_update() to apply COUNT values to the PDCP entity:
- Computes tx_next, rx_next, and rx_deliv from HFN+SN
- Handles both 12-bit and 18-bit SN modes with dynamic bitmask
* Introduced nr_pdcp_get_drb_count_values() to extract PDCP COUNT values from entity:
- Used for building UL RAN Status Transfer on source CU side
Introduce a new timer for the use case where a UE should not be
scheduled anymore after a certain time. This is the case, for instance,
during handover, where the "source DU" forwards the RRCReconfiguration
and should stop scheduling this UE after some time.
Originally, transm_interrupt was introduced in 5c6d90aaff ("Use
NR_timer_t for UE transmission interrupt, e.g., RRC processing") to stop
scheduling a UE.
Commit 004403c84d ("Implement F1 UE Ctxt Modif Transmission Action
Indicator") reused this timer in an attempt to save code with an
"interrupt follow action".
In commit 89ebbb4192 ("Do not trigger ul failure in measgap scheduling
and standardize the verification if MAC is active in other scheduling
functions"), the transm_interrupt timer is used to not schedule a UE
through function nr_mac_ue_is_active(). This led to the UE not being
forwarded the RRCReconfiguration, effectively breaking handover, as the
message never reaches the UE. By using a new timer, the intended
functionality is restored.
Fixes: 89ebbb4192 ("Do not trigger ul failure in measgap scheduling
and standardize the verification if MAC is active in other
scheduling functions")
Remove this flag, as it is not used as of this commit, and introduces
confusion (see next commit: we reused the trans_interrupt timer for
the transmission action indicator stop action, where the UE should stay
active, while it is *not* when transm_interrupt is active).
Fix UE DCI monitoring after RRC setup
After the UE is configured with pdcch-Config, it continues to monitor
fallback search spaces in pdcch-ConfigCommon for DCI with C-RNTI.
The rational is that after sending RRC Setup the network won't know if
the UE has received and successfully applied it. Hence the network would
still continue to use the fallback DCI till it receives RRC setup
complete.
Closes#954
After the UE is configured with pdcch-Config, it continues to monitor
fallback search spaces in pdcch-ConfigCommon for DCI with C-RNTI.
The rational is that after sending RRC Setup the network won't know if
the UE has received and successfully applied it. Hence the network would
still continue to use the fallback DCI till it receives RRC setup
complete.
Refactor measConfig
- Refactor and minor improvements in get_MeasConfig function;
- Add support for band in neighbourConfiguration (It is currently
possible to handover cells with different frequencies, as long as they
are in the same band, but this MR allows the handover to also be done
between cells in different bands).
Reworking BWP configuration
This MR reworks the configuration via fail of additional BWPs. Moreover, it
allows for a single BWP to be configured for a given UE at a given time (BWP
switch possible only via reconfiguration). It also reworks PTRS configuration
for consistency with the BWP one.
Fixes and updates for UL scheduling, notably DSUUU
Fix a number of problems that stem from !3521, notably regarding Msg3
scheduling, retransmissions in "UL-heavy" TDD scenarios, and BSR
handling. Modify a CI test to run a UL-heavy TDD scenario, and add
documentation for UL-heavy TDD scenarios.
In high throughput UL scenarios, at least with our configuration, the UE
only sends Short BSR. The maximum is 300000 bytes, which is completely
"scheduled away" after a couple of UL grants. Increase the periodic BSR
to 5ms to get more BSR, which results in higher UL throughput.
On BSR reception, reset sched_ul_bytes. This change means that we assume
that no data is "in flight" for this UE at time of BSR reception, or,
put differently, that we overestimate the buffer size at UE (in the
worst case).
To illustrate this, consider the following traces before/after this
change.
Before this change: Upon BSR reception, the estimated BSR of the UE is
reset, but the gNB still accounts for data "in flight". It is visible
that the calculated buffer size (estimated - scheduled) quickly goes to
zero, and we don't use all resources, despite the buffer still being
full. The maximum application throughput in this run was ~220Mbps.
[NR_MAC] SHORT BSR at 773.19, est buf 300000
[NR_MAC] ULSCH/PUSCH: 774. 6 RNTI af8e UL sched 774. 9 PRB start 0:162 TDA 2 TBS 32797 est 300000 sched 152704 est BSR 147296 TPC 1
[NR_MAC] ULSCH/PUSCH: 774. 6 RNTI af8e UL sched 774.11 PRB start 0:162 TDA 4 TBS 7172 est 300000 sched 159876 est BSR 140124 TPC 1
[NR_MAC] ULSCH/PUSCH: 774.10 RNTI af8e UL sched 774.12 PRB start 0:162 TDA 0 TBS 32797 est 292845 sched 185501 est BSR 107344 TPC 1
[NR_MAC] ULSCH/PUSCH: 774.10 RNTI af8e UL sched 774.13 PRB start 0:162 TDA 2 TBS 32797 est 292845 sched 218298 est BSR 74547 TPC 1
[NR_MAC] ULSCH/PUSCH: 774.11 RNTI af8e UL sched 774.14 PRB start 0:162 TDA 2 TBS 32797 est 260117 sched 218298 est BSR 41819 TPC 1
[NR_MAC] ULSCH/PUSCH: 774.11 RNTI af8e UL sched 774.16 PRB start 0:162 TDA 4 TBS 7172 est 260117 sched 225470 est BSR 34647 TPC 1
[NR_MAC] ULSCH/PUSCH: 774.15 RNTI af8e UL sched 774.17 PRB start 0: 35 TDA 0 TBS 7172 est 220236 sched 185501 est BSR 34735 TPC 1
[NR_MAC] ULSCH/PUSCH: 774.15 RNTI af8e UL sched 774.18 PRB start 0:162 TDA 2 TBS 32797 est 220236 sched 218298 est BSR 1938 TPC 1
[NR_MAC] ULSCH/PUSCH: 774.16 RNTI af8e UL sched 774.19 PRB start 0: 10 TDA 2 TBS 2017 est 187508 sched 187518 est BSR -10 TPC 1
[NR_MAC] SHORT BSR at 774. 9, est buf 300000
[NR_MAC] ULSCH/PUSCH: 775. 0 RNTI af8e UL sched 775. 2 PRB start 0:162 TDA 0 TBS 32797 est 260117 sched 147549 est BSR 112568 TPC 1
[NR_MAC] ULSCH/PUSCH: 775. 0 RNTI af8e UL sched 775. 3 PRB start 0:162 TDA 2 TBS 32797 est 260117 sched 180346 est BSR 79771 TPC 1
[NR_MAC] ULSCH/PUSCH: 775. 1 RNTI af8e UL sched 775. 4 PRB start 0:162 TDA 2 TBS 32797 est 227389 sched 180346 est BSR 47043 TPC 1
[NR_MAC] ULSCH/PUSCH: 775. 1 RNTI af8e UL sched 775. 6 PRB start 0:162 TDA 4 TBS 7172 est 227389 sched 187518 est BSR 39871 TPC 1
[NR_MAC] ULSCH/PUSCH: 775. 5 RNTI af8e UL sched 775. 7 PRB start 0:162 TDA 0 TBS 32797 est 180353 sched 173174 est BSR 7179 TPC 1
[NR_MAC] ULSCH/PUSCH: 775. 5 RNTI af8e UL sched 775. 8 PRB start 0: 36 TDA 2 TBS 7298 est 180353 sched 180472 est BSR -119 TPC 1
After this change: The gNB resets the number of bytes "in flight"
(sched). Thus, the calculated buffer is larger, and does not "run out"
before a new BSR arrives (which still indicates the maximum). The UE is
thus allocated all resources, but we might overestimate some resources.
The maximum application throughput in this run was ~300Mbps, limited by
MCS and not by estimated buffer size as in the previous case.
[NR_MAC] SHORT BSR at 43. 3, est buf 300000
[NR_MAC] ULSCH/PUSCH: 43.15 RNTI d3ea UL sched 43.17 PRB start 0:162 TDA 0 TBS 36897 est 263180 sched 36897 est BSR 226283 TPC 1
[NR_MAC] ULSCH/PUSCH: 43.15 RNTI d3ea UL sched 43.18 PRB start 0:162 TDA 2 TBS 36897 est 263180 sched 73794 est BSR 189386 TPC 1
[NR_MAC] ULSCH/PUSCH: 43.16 RNTI d3ea UL sched 43.19 PRB start 12:150 TDA 2 TBS 33822 est 263180 sched 107616 est BSR 155564 TPC 1
[NR_MAC] ULSCH/PUSCH: 43.16 RNTI d3ea UL sched 44. 1 PRB start 0:162 TDA 4 TBS 7941 est 263180 sched 115557 est BSR 147623 TPC 1
[NR_MAC] ULSCH/PUSCH: 44. 1 RNTI d3ea UL sched 44. 3 PRB start 0:162 TDA 0 TBS 36897 est 173698 sched 25881 est BSR 147817 TPC 1
[NR_MAC] ULSCH/PUSCH: 44. 1 RNTI d3ea UL sched 44. 4 PRB start 0:162 TDA 2 TBS 36897 est 173698 sched 62778 est BSR 110920 TPC 1
[NR_MAC] ULSCH/PUSCH: 44. 1 RNTI d3ea UL sched 44. 6 PRB start 0:162 TDA 4 TBS 7941 est 173698 sched 70719 est BSR 102979 TPC 1
[NR_MAC] SHORT BSR at 43.13, est buf 300000
[NR_MAC] ULSCH/PUSCH: 44. 5 RNTI d3ea UL sched 44. 7 PRB start 0:162 TDA 0 TBS 36897 est 292079 sched 36897 est BSR 255182 TPC 1
[NR_MAC] ULSCH/PUSCH: 44. 5 RNTI d3ea UL sched 44. 8 PRB start 0:162 TDA 2 TBS 36897 est 292079 sched 73794 est BSR 218285 TPC 1
[NR_MAC] ULSCH/PUSCH: 44. 6 RNTI d3ea UL sched 44. 9 PRB start 0:162 TDA 2 TBS 36897 est 292079 sched 110691 est BSR 181388 TPC 1
[NR_MAC] ULSCH/PUSCH: 44. 6 RNTI d3ea UL sched 44.11 PRB start 0:162 TDA 4 TBS 7941 est 292079 sched 118632 est BSR 173447 TPC 1
[NR_MAC] ULSCH/PUSCH: 44.10 RNTI d3ea UL sched 44.12 PRB start 0:162 TDA 0 TBS 36897 est 213587 sched 39972 est BSR 173615 TPC 1
[NR_MAC] ULSCH/PUSCH: 44.10 RNTI d3ea UL sched 44.13 PRB start 0:162 TDA 2 TBS 36897 est 213587 sched 76869 est BSR 136718 TPC 1
gNB: adaptive DL/UL MCS based on reported SSB-SINR and measured PUSCH SNR
Currently this is used esp. if the number of rounds is limited to 1
(e.g. disable_harq).
Revert "Removed TRP-scheme byte from UL BF PDU to Interop with Aerial 25-1 (FAPI 10.02)"
This commit broke compatibility with Aerial when compiled with
-DSCF_FAPI_10_04_SRS=ON. It was decided that this should become the
default.
Modify documentation, and use a dedicated image name to make it clear in
the CI that it has SRS.
This commit broke compatibility with Aerial when compiled with -DSCF_FAPI_10_04_SRS=ON. It was decided that this should become the default.
This reverts commit 8beb382277.
Instead of only saving this information in the first transmission, also
store it on each retransmission. This should ensure that if some
information changes, we always relate to the last transmission. For
instance, power control information might have changed, and should be
considered in subsequent rounds, if necessary. It also simplifies code.
Fixes: 6294ce715e ("Reorder pf_ul to process retransmission")
In at least the case of mu=1, min_rxtxtime=2 and DDDSU with no UL
symbols (for ULSCH) in the mixed slot, the current state of code does
not allow a UE to attach. This is because at mu=1, Msg3 is k2+delta,
where k2=min_rxtxtime and delta(mu)=3.
Prior, this special case was handled because we had a dedicated Msg3
TDA, which in most cases is not necessary (because the mixed slot
allocates the DCI, and the following mixed slot has the UL grant). Add
code that tries to ensure that we only add the Msg3 TDA in cases when we
need it.
Fixes: 961a646dc7 ("Remove dedicated Msg3 TDA")
reset MSG3 C-RNTI flag in case of failure
If MSG3 with C-RNTI fails, the UE should come back with a
re-establishment (after a given number of RA failures in general). In
that case, the OAI UE wouldn't reset the MSG3 with C-RNTI flag leading
to re-establishment failure.
NR UE: add support for PDSCH rate matching with NZP CSI-RS
Currently only ZP CSI-RS is considered in function
configure_ratematching_csi, add support for NZP CSI-RS.
Closes#975
Previously, the TDA reuse condition was wrong: for multiple TDAs with
different k2, the symbol allocation might be the same, in which the
previous logic was using the wrong TDA. Fix the condition, and insert an
assert to ensure the allocated TDA is correct.
francescomani