The PDUSessionResourceReleaseResponse message was missing the mandatory
pDUSessionResourceReleaseResponseTransfer IE in each released PDU session item. This caused Open5GS to send an error indication.
Changes:
- Add encode_ngap_pdusession_release_response_transfer() function to
properly encode the transfer structure (empty since Secondary RAT Usage
Information is optional and not used, per 9.3.4.21)
- Always include the mandatory PDUSessionResourceReleasedListRelRes IE
- Always encode the pDUSessionResourceReleaseResponseTransfer for each
PDU session item
- Fix Release Command handler to decode and log Cause from command transfer:
instead of incorrectly copying command data to response: the 2 transfer
IEs in the Command and the Response messages are different and should
not be mixed
- Split Command/Response struct type definitions
- Add missing includes
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>
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 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>
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
Guido Casati