According to TS 38.463 - clause 9.2.2.4 and 9.3.3.12.
Also, fix response message by encoding choice IE only
with presence of modified PDU sessions.
Co-authored-by: rmagueta <rmagueta@allbesmart.pt>
This commit is removing the storage of selected PLMN in NGAP UE context.
We store the Serving PLMN in the RRC UE context instead.
The Selected PLMN is the PLMN that the UE chose (or was directed to) for registration
and it is sent in the RRCSetupComplete. This is different from the selected
PLMN mentioned in the NG INITIAL UE MESSAGE for network sharing.
Selected PLMN: determines which core network and AMF the UE is registered with
GUAMI = Identifies the serving AMF and includes the PLMN of that AMF
Serving PLMN: the PLMN that is currently serving the UE (e.g. contained in GUAMI)
The AMF’s PLMN may match the selected PLMN, or not (especially in network sharing or roaming).
Regardless, the UE always have a Serving PLMN.
Initial UE message does not have a TAI IE per se, but TAI is a mandatory
member of the mandatory UserLocationInformation CHOICE.
NR CGI is also mandatory and carried inside UserLocationInformation:
in network sharing, the PLMN ID in TAI takes on additional
significance: RAN is shared but CN are different, so in this case PLMN in TAI is
needed for the AMF route the message to the correct operator’s core.
If network sharing applies (e.g., shared RAN between PLMN-A and PLMN-B):
the UE or network may select PLMN-B instead, and that PLMN identity
is included in the Initial UE Message’s TAI IE.
Conclusion:
1) UE always sends the selected PLMN during the registration,
regardless of whether it is shared or not.
2) Selected PLMN Identity is an actual IE sent in the RRCSetupComplete
while in NGAP there's no Selected PLMN Identity IE, only PLMN Identity
IEs in both TAI and NR CGI. It is a subtle difference.
3) The serving PLMN of the UE needs to be stored in RRC UE Context for
later use in NAS procedures. e.g. at initial registration it matches
the Selected PLMN
4) No need to store PLMN in NGAP UE Context, params are passed by RRC
5) TAI and NR CGI, which contain the PLMN identity, are mandatory in
UserLocationInformation IE CHOICE, and should reflect current status
Changes
- Initial UE Message: pass UE-selected PLMN and NR cell id from RRC to NGAP
- Uplink NAS Transport: use PLMN, TAC, and cell id provided by the message;
- Build NR CGI from gNB ID + cell id
- Store UE-selected PLMN only in RRC UE context at NAS_FIRST_REQ for later
Uplink NAS, stop storing PLMN in NGAP UE context
Remove NR L2 simulator code from UE
This MR removes NR (SA and NSA) L2 simulator from the codebase. The code, at
least at the UE side, was done at a time where there was no clear L2/L1 split
leading to a complex implementation that never worked as expected. The L2
simulator has been broken and removed from testing for long time and, once it
needs to be revived, it would require a complete new implementation.
* There is no IE corresponding to PDU sessions failed to release
in the PDU SESSION RESOURCE RELEASE RESPONSE message. This was removed
and the corresponding code was refactored and cleaned up.
* In the Release Command handler, only established PDU Session are set to be
released. The Response message is filled accordingly.
- Move QoS-related enums and structures from ngap_messages_types.h to 5g_platform_types.h
- Replace ngap_* QoS types with generic qos_* types for better reusability
- Update field names from allocation_retention_priority to arp for consistency
- Update all references across RRC and NGAP modules to use new type names
- Remove duplicate QoS type definitions from NGAP-specific header
This improves code organization by centralizing QoS parameter definitions
in a common platform types header and eliminates NGAP-specific naming
in favor of more generic, reusable type definitions.
The maximum number of QoS flows is 64.
- Replace QOSFLOW_MAX_VALUE with MAX_QOS_FLOWS constant
- Move MAX_QOS_FLOWS definition to common/platform_constants.h
- Remove duplicate QOSFLOW_MAX_VALUE definition from ngap_messages_types.h
This improves maintainability by centralizing the QoS flow limit constant
and eliminates duplicate definitions across different header files.
Previously, the RRC layer was incorrectly allocating stack memory for the ho_required_transfer field and passing it to NGAP, however it was not used. The IE is mandatory but contains only 1 optional IE, therefore is encoded in the NG message with empty content.
Changes:
- Remove unnecessary ho_required_transfer field from pdusession_resource_t definition, the IE is encoded anyway with empty content. If Direct Forwarding Path Availability is needed at any stage in the future it can be added to pdusession_resource_t and filled in RRC.
- Add clarifying comment about empty HandoverRequiredTransfer structure
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.
This commit completes the NGAP Mobility Management procedure for N2 handover.
Upon failure on source gNB the Handover Cancel message is sent to the AMF which
in return responds with an ack.
According to 4.9.1.3.3 of 3GPP TS 23.502:
> 2a. - 2c. The S-RAN sends the Uplink RAN Status Transfer message to the S-AMF,
> as specified in TS 36.300 [46] and TS 38.300 [9]. The S-RAN may omit sending
> this message if none of the radio bearers of the UE shall be treated with PDCP status preservation.
TS 38.300 says:
> For DRBs not configured with DAPS, the source gNB sends the SN STATUS TRANSFER message to the target
> gNB to convey the uplink PDCP SN receiver status and the downlink PDCP SN transmitter status of DRBs for
> which PDCP status preservation applies (i.e. for RLC AM). The uplink PDCP SN receiver status includes at
> least the PDCP SN of the first missing UL PDCP SDU and may include a bit map of the receive status of the out
> of sequence UL PDCP SDUs that the UE needs to retransmit in the target cell, if any. The downlink PDCP SN
> transmitter status indicates the next PDCP SN that the target gNB shall assign to new PDCP SDUs, not having a
> PDCP SN yet.
i.e., for DRBs for which PDCP status preservation applies (i.e. for RLC AM), which is is our case.
This commit introduces full support for NG-RAN Status Transfer message handling
(TS 38.413 §9.2.3.13-14) in CU. It enables correct state transfer of PDCP COUNT
values (SN + HFN) during mobility or recovery scenarios.
Summary of changes - NGAP:
* Added encoding/decoding support for UL/DL RAN Status Transfer message
* Defined structures for: ngap_drb_count_value_t, ngap_drb_status_t,
ngap_ran_status_container_t, ngap_ran_status_transfer_t
This commit introduces the NG Mobility Management Procedure known as
Handover Notification. The outbound message is sent by the target NG-RAN
and is known as Handover Notify. The procedure is used to indicate to
the AMF that the UE has arrived to the target cell and the NG-based
handover has been successfully completed
* after RRCReconfiguration complete, in the N2 callback for HO success
* add NGAP encoder for the message
* RRC callback to trigger Handover Notify message
Co-authored-by: batuhan duyuler <batuhan.duyuler@firecell.io>
* add NG Handover Command message decoder
* process in RRC: encode RRCReconfiguration message
from the received HandoverCommandMessage
* trigger RRCReconfiguration for handover
Co-authored-by: batuhan duyuler <batuhan.duyuler@firecell.io>
This commit completes the NG Mobility Management Procedure known as
Handover Resource Allocation. The outbound message is sent by the
target NG-RAN and is known as Handover Request Acknowledge.
Major changes:
* add RRC callback to trigger the generation of NG Handover
Request Acknowledge on the target NG-RAN
* add NG Handover Request Acknowledge encoder
Co-authored-by: batuhan duyuler <batuhan.duyuler@firecell.io>
This commit introduces the NG Mobility Management Procedure known as
Handover Resource Allocation. The inbound message is sent by the AMF
and is known as Handover Request.
Major changes:
(0) Add Handover Resource Allocation initiating message decoding
* add case for NGAP initiating message and unsuccessful message decoding
(1) handle Handover Request on the target NG-RAN
(2) decode NG Handover Request message
(3) process payload, e.g. create UE context,
store IDs, set UP security and trigger bearer setup
Co-authored-by: batuhan duyuler <batuhan.duyuler@firecell.io>
This message is sent from the Target NG-RAN to the AMF.
The commit introduces:
* NGAP encoding function
* N2 callback for the target gNB
* handle the failure in RRC, inform NGAP
* send NGAP message to AMF via SCTP
Note: UE context in NGAP is fetched from the amf_ue_ngap_id
Co-authored-by: batuhan duyuler <batuhan.duyuler@firecell.io>
This commit introduces the NG Mobility Management Procedure known as
Handover Preparation. The outbound message is sent by the source NG-RAN
and is known as Handover Required.
* introduce NGAP library for Mobility Management
* introduce NGAP IEs encoder functions for Handover Required and relevant common IEs
* handle RRC trigger in NGAP and Send NGAP Handover Required to the AMF
Co-authored-by: batuhan duyuler <batuhan.duyuler@firecell.io>
- Replaced ITTI message queues with notifiedFIFO for RRC to MAC communication in UE.
- Enables correct message delivery to multiple MAC instances running in parallel threads.
- Introduced `nr_mac_rrc_message_t` union for MAC-RRC messages.
- Updated all relevant message handling and initialization code to use notifiedFIFO.
bugfix: UE AMBR is optional
This was a problem with open5gs and more than one PDU session. The core network
sets UE AMBR only once, leading to failure in the gNB for the second PDU session.
(A proper handling of AMBR has to be develop at some point in the gNB.)
This was a problem with open5gs and more than one PDU session.
The core network sets UE AMBR only once, leading to failure in the gNB
for the second PDU session.
(A proper handling of AMBR has to be develop at some point in the gNB.)
continuously update SIB19 information for rfsim NTN LEO scenarios
Contains mainly these changes:
- gNB: add function nr_update_sib19() allowing to update SIB19
information
- rfsimulator: update SIB19 contents every frame for LEO channel
simulations
- NR UE: improve initial timing advance calculation from SIB19
Before, we only considered ta_Common_r17 and the SAT position from SIB19
to compute the initial timing advance value. This is good enough if the
satellite does not move too fast (e.g. GEO satellite).
Now we also consider ta_CommonDrift_r17, ta_CommonDriftVariant_r17 and
the SAT velocity together with the epoch time from SIB19. This improves
the accuracy of the initial TA computation, esp. for LEO satellite
scenarios.
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.
Similarly to the commit "Use F1 UE context setup/modif Request in
stack", we do both UE context setup/modification response at once
because of some functions that are shared by the MAC message handler.
Use the new, tested F1 UE context setup request and modification
requests in the stack.
We have to do both at once, because there are some functions that are
used by handlers for both messages, notably
- handle_ue_context_drbs_setup()
- handle_ue_context_srbs_setup()
(+ and some functions called by those two). For instance, the first uses
the (new/old) type f1ap_drb_to_be_setup_t/f1ap_drb_to_setup_t which is
shared. The alternative would be to duplicate the functionality
temporarily, and I want to avoid unnecessary code churn.
Reintroduce separate message types to simplify the encoding/decoding,
including shorter names. The old types will be removed once everything
has been migrated to the new encoder/decoder, which should ensure that
everything is properly migrated to the unit-tested encoder/decoders.
Also, for each type of F1 message (F1 UE context setup request,
response, modification request, ...) introduce a separate type to avoid
to mistakenly use wrong fields, which can lead to bugs. In this regard,
the DL PDCP SN bit size in the DRB-ToBeSetup list of the UE context
setup request is optional, as it will also be used in the UE context
modification request DRB SetupMod list (which avoids quite some code
duplication). The encoder checks that this IE is present, though.
Cleanup PDU Session Handling in RRC/NGAP
Currently, NGAP and RRC share the same structures and responsibilities when
handling PDU Session information: this creates tight coupling, redundancy, and
makes the code harder to maintain.
- NGAP should be responsible only for: Protocol-specific encoding/decoding
(3GPP TS 38.413)
- RRC should own: PDU Session handling and storage in the UE context
This MR is the first step in a broader refactoring of the PDU Session handling
code across NGAP and RRC layers, with the goal of splitting responsibilities
cleanly between both modules.
- Unified gtpu_tunnel_t for tunnel endpoint config (formerly f1u_tunnel_t)
- Refactored and relocated PDU Session struct definitions for better separation
between NGAP and RRC
- Moved pdusession_t for PDU Session handling out of NGAP, now defined and
managed by RRC only
- Defined 3GPP TS 38.413 message-specific structs in NGAP module
- NGAP now decodes NGAP PDU Session Resource Setup/Modify IEs and transfers
decoded data to RRC via ITTI
- Add helper functions to copy from NGAP message to pdusession_t
- Introduced new encoders/decoders/helpers in NGAP for handling PDU Session
Resource Setup/Modify procedures (e.g. decode_pdusession_transfer)
- Migrated to NGAP and removed duplicated logic for QoS information decoding
(fill_qos)
- Improved logging of GTP tunnel info
- Merged redundant functions (f1u_dl_gtp_update and f1u_ul_gtp_update)
- Removed unused code and obsolete types
- do free_func in seq_arr_erase_it on the provided range and updated unit test
- Other fixes and simplifications (e.g. simplified and clarified naming of
tunnel/session parameters and structs)
This cleanup improves code readability, has a high code churn (the deletions are
~159.7% of the insertions) and prepares for better modularity before the
refactoring of PDU Session handling in RRC/NGAP.
Motivation of the commit:
Previously, the RRC module on the NGAP interface directly handled ASN.1 decoding
of NGAP PDU Session Resource items, that was directly stored in pdusession_t, i.e.
in the UE context. Decode logic between Setup and Modify was also duplicated.,
e.g. fill_qos/fill_qos2. The idea behind this change is to achieve this flow:
(1) NGAP handler: decoding (2) ITTI to RRC: transfer decoded message (3) RRC
handler: process decoded message, e.g. store in UE context, etc..
The goal of this commit is to:
* improve the NGAP decoding library by adding decoding functions
* let RRC handle the already decoded data
* enhance error handling, with decode failures now consistently detected and rejected early
* have a cleaner, more maintainable code with fewer duplications and a clearer separation of modules
Changes:
* Moved all ASN.1 decode logic for PDU Session Resource items into the NGAP library
* Introduced decode functions for NGAP IEs whenever necessary, e.g. decode_TNLInformation
decode_pdusession_transfer
* Removed duplicate fill_qos functions and centralized QoS handling in NGAP
* Added function to copy from NGAP PDU Session Resource item to RRC pdusession_t: this actually
replaces decodePDUSessionResourceSetup in RRC, copying from the decoded NGAP struct to
the UE context pdusession_t
