Enhancements of ran timing synchronization status reporting

Abstract

Methods performed by RAN node and a core network node are provided and comprise receiving timing synchronization status (TSS) reporting control information from the core network node, the timing synchronization status reporting control information comprising any one or more of the following information elements a routing identifier (ID), that identifies a requestor of corresponding TSS reports; an identifier of a network slice for which the timing synchronization status reporting control information applies; one or more thresholds for one or more TSS attributes provisioned on the RAN node to trigger the RAN node to generate a TSS report towards the core network; or a validity time for the timing synchronization status reporting control information. The method further comprises sending TSS report comprising the identity of the TSS requestor. Alternatively, the RAN node can send TSS failure message in response to the TSS request.

Description

ENHANCEMENTS OF RAN TIMING SYNCHRONIZATION STA TUS REPORTINGRELATED APPLICATIONS

[0001] This application claims the benefit of provisional patent application serial number 63 / 616006, filed on 12 / 29 / 2023 and 63 / 617850 filed on 1 / 5 / 2024, the disclosure of which are hereby incorporated herein by reference in its entirety. Technical Field

[0002] The present disclosure relates to a cellular communications system and, more particularly, to timing synchronization status reporting in a cellular communications system.Background

[0003] Third Generation Partnership Project (3GPP) Technical Specification (TS) 23.502 V18.4.0, Clause 4.15.9.1 states "Time synchronization exposure allows an AF to configure time synchronization in 5GS. For (g)PTP operation, the Time synchronization service allows an AF to subscribe to the UE and 5GC capabilities and availability for time synchronization service (as described in clause 4.15.9.2), to configure the (g)PTP instance in 5GS as described in clause 4.15.9.3 and monitor service status as described in clause 4.15.9.5." As described in 3GPP TS 23.502 V18.4.0, Clause 4.15.9.5, upon the reception of the clock quality detail level and clock quality acceptance criteria (if applicable) in the Application Function (AF) request, the Time-Sensitive Communication Time Synchronization Function (TSCTSF) needs to be subscribed to Next Generation Radio Access Network (NG-RAN) timing synchronization status updates at the NG-RAN nodes that may provision access stratum time distribution information to the target User Equipment (UE). See the latest requirements in clause 4.15.9.5 of 3GPP TS 23.502 V18.4.0 shown in the excerpt below (emphasis added via bold text):***** START EXCERPT FROM 3GPP TS 23.502 V18.4.0 *****0. TheAF requests creation or modification of ASTI or PTP based time synchronization service as described in clauses 4.15.9.4 and 4.15.9.3 including clock quality detail level and clock quality acceptance criteria (if applicable) in the request.If the request is received at the NEF, it checks whether the AF is authorized to send the request and forwards the request to the TSCTSF. If network timing synchronization status reports are provisioned using node-level signalling via control plane, the TSCTSF determines the serving AMF(s) and the UPF / NW-TT nodes (if applicable) for the UE(s) that needs to initiate network timing synchronization status monitoring.Otherwise, if network timing synchronizations status reports are provisioned via 0AM, steps 1-3 and 5-7 are skipped.1-2. (When the procedure is triggered by the AF request to influence the 5G access stratum time distribution or by PTP instance activation, modification):Upon the reception of the clock quality detail level and clock quality acceptance criteria (if applicable) in the AF request in step 0, the TSCTSF needs to be subscribed to NG-RAN timing synchronization status updates at the NG-RAN nodes that may provision access stratumtime distribution information to the target UE. NG-RAN timing synchronization status updates provisioning may be configured viaAMF (with node level signalling as illustrated in steps 1-2).The TSCTSF sends Namf_Communication_NonUeN2InfoSubscribe to initiate the subscription for the NG-RAN timing synchronization status updates from theAMF. As part of this subscription, the TSCTSF may specify TA(s) and / or NG-RAN node(s) in the subscription for the timing synchronization status reporting. Based on local configuration and / or TA or NG-RAN node information as received from the TSCTSF, the AMF may subscribe to some or all NG-RAN nodes in the TA(s) for the timing synchronizations status reporting.3. (When the procedure is triggered by the AF request for PTP instance activation, modification and if the UPF / NW-TT is involved in providing time information to DS-TT):Upon the reception of the clock quality acceptance criteria in the AF request in step 0, the TSCTSF needs to be subscribed to UPF / NW-TT timing synchronization status updates at the UPF / NW-TT that may provision time information via PTP to the target UE. UPF / NW-TT timing synchronization status updates provisioning may be configured via 0AM or via UMIC.4. The RAN node is pre-configured for the thresholds for each timing synchronization status attribute as described in clause 5.27.1.12 of TS 23.501 [2]. When the network timing synchronization status exceeds or meets again any of the pre-configured thresholds, the NG-RAN node detects a change on its timing synchronization status (e.g., degradation, failure, improvement).5-6. If the NG-RAN node detects a change on its timing synchronization status as described in clause 5.27.1.12 ofTS 23.501 [2] and the timing synchronization status reporting is configured via the AMF in step 1, the NG-RAN node notifies the AMF providing a NG-RAN timing synchronization status update. The update can contain the information elements listed in Table 5.27.1.12-1 ofTS 23.501 [2], and the scope of the timing synchronization status (as described in clause 5.27.1.12 ofTS 23.501 [2]). TheAMF forwards the update to the subscribed TSCTSF.***** END EXCERPT FROM 3GPP TS 23.502 V18.4.0 *****

[0004] Before going into discussion on how the TSCTSF subscribes to NG-RAN timing synchronization status reporting (Step 1-2), in Step 0, an AF requests a creation or modification of an Access Stratum Time distribution status Information (ASTI) or (generalized) Precision Time Protocol ((g)PTP)-based time synchronization service. The procedures for this are described in clauses 4.15.9.4 and 4.15.9.3 of 3GPP TS 23.502 V18.4.0, respectively. In the context of the present disclosure, it is important to emphasize that a request may include a "Temporal Validity Condition", i.e., start and stop times when the service shall be active, see the following excerpts from the 3GPP TS 23.502 V18.4.0 (emphasis added via bold, italicized text):#— clause 4.15.9.4 of TS 23.502 [1]—Table 4.15.9.4-1: Description of 5G access stratum time distribution parameters#— -clause 4.15.9.3 of TS 23.502 [1]The Nnef TimeSynchronization ConfigCreate and Nnef TimeSynchronization ConfigUpdate request may contain the parameters as described in Table 4.15.9.3-1.Table 4.15.9.3-1: Description of Time Synchronization service parameters

[0005] Then, when it comes to NG-RAN reporting timing synchronization attributes, these attributes are defined in clause 5.27.1.12 of TS 23.501 V18.4.0 as shown in the following excerpt:#— clause 5.27.1.12 of TS 23.501 —The network timing synchronization status information fromgNB or UPF / NW-TT to the TSCTSF may contain the following information as described in the Table 5.27.1.12-1. The details for gNB timing synchronization status information are specified in TS 38.413

[0034] , However, it is up to gNB to determine whether to provide its timing synchronization status reporting and which of the information elements to include in the TSS report to the TSCTSF, i.e. based on the implementation gNB may report all, some, or none of the information elements from Table 5.27.1.12-1.Table 5.27.1.12-1: Information elements that gNB or UPF / NW-TT timing synchronization status information may contain (all optional)

[0006] Timing Synchronization Status (TSS) attributes from Table 5.27.1.12-1 of 3GPP TS 23.501 V18.4.0 can also be used to set the corresponding thresholds instructing when the NG-RAN needs to report the attribute values to the TSCTSF (via the Access and Mobility Management Function (AMF), as shown in the following excerpt:# — excerpt also from clause 5.27.1 .12 of TS 23.501 — gNBs may be pre-configured with thresholds for each Timing Synchronization Status (TSS) attribute, if supported, that is described in Table 5.27.1.12-1. gNBs may include a reference report ID in SIB information, if supported. A reference report ID consists of a scope of the TSS and an Event ID. A scope of the TSS supports providing TSS information for all cells or a group of cells within a single gNB. Event ID is an integer indicating that the gNB's clock quality has changed, resulting in at least one TSS attribute exceeding or meeting again the pre-configured threshold. Uniqueness of Event ID value is ensured by combining it with a gNB ID as specified in TS 38.300

[0027] , When the network TSS attribute exceeds the thresholds (Le. status degradation), or the network TSS attribute meets the thresholds again (Le. status improvement), the gNB notifies the TSCTSF (either using N2 node level signalling via AMF, or via OAM) with the scope of the timing synchronization status (Le. gNB ID or a list of Cell IDs within a single gNB) and the corresponding network timing synchronization status attributes as described in Table 5.27.1.12-1. The gNB indicates the status change to the UEs via the reference report ID change in SIB information:When the network timing synchronization status exceeds any of the pre-configured thresholds (i.e. status degradation) or meets the threshold again (i.e. status, improvement), the gNB changes the reference report ID in SIB information. Either event serves as a notification for the UEs reading the SIB information that there is new TSS information available.NOTE 1 : NG-RAN is assumed not to provide clock quality metrics better than the pre-configured threshold, i.e. if a clock quality metric is better than the corresponding threshold, the NG-RAN reports the threshold value to the UE in an RRC message instead.NOTE 2: It is assumed the pre-configured thresholds in the gNB(s) are sufficient to meet UE time sync performance requirement which are configured by the operator.#—

[0007] Moving forward to Step 1-2 in the procedure defined in clause 4.15.9.5 of 3GPP TS 23.502, there is a discussion in 3GPP SA2 and CT4 working groups about whether the TSCTSF shall use Namf_Communication_NonUeN2MessageTransfer to directly request the NG-RAN to start or stop timing synchronization status update report. The following two alternatives are considered:

[0008] Alternative 1: UsingNamf_Communication_NonUeN2MessageTransfer.

[0009] As illustrated in Figure 1, in Alternative 1, when doing activation, the Namf_Communication_NonUeN2MessageTransfer Request message in step 1 of Figure 1 would include an N2 Container encapsulating the NGAP message "TIMING SYNCHRONISATION STATUS REQUEST", and the AMF will TRANSPARENTLY forward the message to the concerning NG-RAN nodes in step 2 of Figure 1 based on the Tracking Area Identity (TAI) List or NG-RAN node identifiers (IDs). The AMF will transparently forward the response message from the concerned NG-RAN nodes, either accept or failure result, via the Namf_Communication_NonUeN2MessageTransfer response message in step 6 of Figure 1, e.g. upon the first acceptance result and a Namf_Communication_NonUeN2InfoNotify request if there are a large list of NG-RAN nodes involved and some of NG-RAN nodes respond a little late, (since it is not possible for the AMF to wait for outcome from all NG-RAN nodes). A similar procedure can be used for deactivation.

[0010] Figure 1: RAN timing synchronization status reporting for Alternative 1 that exploits Namf_Communication_NonUeN2MessageTransfer for triggering the reporting

[0011] Alternative 2: Using Namf_Communication_NonUeN2InfoSubscribe.

[0012] Figure 2: RAN timing synchronization status reporting for Alternative 2: Using Namf_Communication_NonUeN2InfoSubscribe for triggering the reporting. As illustrated in Figure 2, in Alternative 2, upon receiving Namf_Communication_NonUeN2InfoSubscribe request from the TSCTSF with a subscription for Time synchronization Status in step 1 of Figure 2, the AMF triggers to send the NGAP "TIMING SYNCHRONISATION STATUS REQUEST" message with START to all concerning NG-RAN nodes, and to keep the state if the NG-RAN node(s) has beenactivated for Time synchronization Status report, so that the AMF can avoid sending the same message again if there is another TSCTSF request that is the same. The AMF considers the Time synchronization status report as being deactivated by the TSCTSF if the AMF receives the Namf_Communication_NonUeN2InfoUnSubscribe request to delete the subscription. However, the AMF deactivates towards the NG-RAN only when no TSCTSF requesting Timing synchronization Status Reporting is left with activated subscription.

[0013] Further in Alternative 1:• The Timing Synchronisation Status Report procedure and its related NGAP messages are not for Mobility Management (MM). In principle, these NGAP messages should be made transparent to the AMF. The AMF offers Namf_communication service to transport these messages between the TSCTSF and NG-RAN, just like it does for the Session Management Function (SMF) (for a Protocol Data Unit (PDU) session), Multicast / Broadcast SMF (MB- SMF) (for a Broadcast MBS session), Cell Broadcast Center Function (CBCF) (for Public Warning messages), Location Management Function (LMF), and so on.• Since the AMF is just providing Communication service, it should not be required to build a non-MM-related message on its OWN; instead, the AMF builds these NGAP messages based on an N2 container (encapsulating a NGAP Information Element (IE) or a NGAP message).• Alternative 1 matches the current design of the AMF communication service for Non UE Related N2 message transferring. Alternative 1 is future proof since the NGAP message can be evolved independent to Namf_communication service, which is the exact merit of AMF communication service.• The main motivation for Alternative 2 is to consider that 3GPP RAN WG3 has designed the Time Synchronization Status Elementary procedure as a NODE level procedure; it is true, but Alternative 1 should be designed as node level procedure as well.• However, Alternative 2 is not future proof; it works only if the TIMING SYNCHRONISATION STATUS REQUEST contains ONLY START and STOP, since the AMF will trigger to send a TIMING SYNCHRONISATION STATUSREQUEST for start based on the Namf_Commmunication_NonUeN2InfoSubscribe Request, and a TIMING SYNCHRONISATION STATUS REQUEST for stop based on the Namf_Commmunication_NonUeN2InfoUnSubscribe Request; • Alternative 1 should be the way forward.

[0014] 3GPP RAN WG3 has agreed NGAP messages to support the Time synchronization status report procedure in R3-238135. Relevant excerpts from R3- 238135 are shown below. ***** START EXCERPTS FROM 3GPP R3-238135 *****8 NGAP Procedures8.1 List of NGAP Elementary ProceduresIn the following tables, all EPs are divided into Class 1 and Class 2 EPs (see subclause 3.1 for explanation of the different classes):Table 8.1-1 : Class 1 proceduresTable 8.1-2: Class 2 procedures***** NEXT EXCERPT FROM 3GPP R3-238135 *****8.xx Timing Synchronisation Status Reporting Procedures 8.xx.1 Timing Synchronisation Status8. xx.1.1 GeneralThe purpose of the Timing Synchronisation Status procedure is to enable the AMF to request the NG-RAN node to start or stop reporting of RAN timing synchronisation status information as specified in TS 23.501 [9] and TS 23.502

[0010] , The procedure uses non-UE associated signalling. 8. xx.1.2 Successful OperationFigure 8.xx.1.2-1 : Timing synchronisation status procedure: successful operationThe AMF initiates the procedure by sending a TIMING SYNCHRONISATION STATUS REQUEST message to the NG-RAN node. If the RA N TSS Request Type IE included in the TIMING SYNCHRONISATION STATUS REQUEST message is set to “start”, the NG-RAN node shall start the RAN TSS reporting. If the RAN TSS Request Type IE is set to “stop”, the NG-RAN node shall stop the reporting.8. xx.1.3 Unsuccessful OperationFigure 8.xx.1.3-1 : Timing synchronisation status procedure: unsuccessful operationIf the NG-RAN node is not able to report timing synchronisation status, it shall consider the procedure as failed and reply with the TIMING SYNCHRONISATION STATUS FAILURE message.8. xx.1.4 Abnormal ConditionsVoid.8.xx.2 Timing Synchronisation Status Report8.xx.2.1 GeneralThe purpose of the Timing Synchronisation Status Report procedure is to enable the NG-RAN node to provide RAN timing synchronisation status information to the AMF as specified in TS 23.501 [9] and TS 23.502

[0010] , The procedure uses non-UE associated signalling.8.xx.2.2 Successful OperationFigure 8.xx.2.2-1 : Timing synchronisation status reportThe NG-RAN node initiates the procedure by sending a TIMING SYNCHRONISATION STATUS REPORT message to the AMF.8.xx.2.3 Abnormal ConditionsVoid.<<<<<<<<<<<<<<<<<<<< Next Change »»»»»»»»»»9.2.yy Timing Synchronisation Status Reporting Messages9.2.yy.1 TIMING SYNCHRONISATION STATUS REQUESTThis message is sent by the AMF to request the NG-RAN node to start or stop reporting of RAN timing synchronization status information.Direction: AMF —> NG-RAN node9.2.yy.2 TIMING SYNCHRONISATION STATUS RESPONSEThis message is sent by the NG-RAN node to confirm the request to start or stop reporting of RAN timing synchronization status information.Direction: NG-RAN node —> AMF9.2.yy.3 TIMING SYNCHRONISATION STATUS FAILUREThis message is sent by the NG-RAN node to indicate that reporting of RAN timing synchronisation status information cannot be initiated.Direction: NG-RAN node —> AMF9.2.yy.4 TIMING SYNCHRONISATION STATUS REPORTThis message is sent by the NG-RAN node to report previously requested RAN timing synchronisation status information.Direction: NG-RAN node —> AMF*****ENDEXCERPTS FROM R3-238135 *****

[0015] Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges.

[0016] A method performed by a Radio Access Network, RAN, node is provided. The method comprises the step of receiving timing synchronization status (TSS) reporting control information from a core network node, the timing synchronization status reporting control information comprises any one or more of the following information elements: a routing identifier (ID), that identifies a requestor of corresponding TSS reports; an identifier of a network slice for which the timing synchronization status reporting control information applies; one or more thresholds for one or more TSS attributes provisioned on the RAN node to trigger the RAN node to generate a TSS report towards the core network; or a validity time for the timing synchronization status reporting control information. For example, the routing ID indicates a Network Function (NF) ID of the requestor of the TSS reports. The NF ID of the requestor may be the ID of a Time-Sensitive Communication Time Synchronization Function in the 3GPP 5G system.

[0017] In other example, the timing synchronization status reporting control information is indicated in a timing synchronization status request message transmitted by the core network node to the RAN node. The RAN node sends a TSS response in response to receiving the TSS request.

[0018] According to an embodiment, the method further comprises the step of sending to the core network node a timing synchronization status report comprising the routing ID comprising the NF ID of the requestor and a RAN TSS scope comprising an identity of the RAN node.

[0019] A method performed by a Radio Access Network, RAN, node is also provided, the method comprises the step of receiving from a core network node a timing synchronization status (TSS) request message to request TSS reporting, the TSS request message comprising an identification of a requestor of TSS reports; and the step of sending, to the core network node, a timing synchronization failure message to indicate that the RAN node has failed to initiate RAN timing synchronization reporting.

[0020] For example, the timing synchronization failure message a RAN TSS scope identifying the RAN node.

[0021] According to an embodiment, a RAN node adapted to perform the embodiments described herein is provided. In another example, a RAN node comprising one or more processors and memory comprising instructions which when executed by the one or more processors enables the RAN node to perform any of the embodiments described herein.

[0022] A method performed by a core network node is provided, the method comprises the step of receiving, from a RAN node, a timing synchronization failure message and the step of sending, to a NF consumer, a message comprising information that identifies the RAN node from which the timing synchronization failure message was received and / or information that identifies an area served by the RAN node from which the timing synchronization failure message was received.

[0023] For example, the method further comprises the step of sending a timing synchronization status request message to the RAN node, wherein receiving the timing synchronization failure message is responsive to sending the timing synchronization status request message.

[0024] For example, the timing synchronization status request message comprises a routing identifier identifying the identity of the NF consumer.

[0025] According to an embodiment, a core network node adapted to perform the embodiments described herein is provided. Alternatively a core network node comprising one or more processors and memory comprising instructions which when executed by the one or more processors enables the core network node to perform any of the embodiments described herein is provided.Brief of the

[0026] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0027] Figure 1 illustrates an alternative (alternative 1) of RAN timing synchronization status reporting according to the prior art;

[0028] Figure 2 illustrates an alternative (alternative 2) of RAN timing synchronization status reporting according to the prior art;

[0029] Figures 3 illustrates example embodiments of a cellular communication system;

[0030] Figures 4 and 5 illustrate example embodiments of the cellular communication system of Figure 3;

[0031] Figure 6 illustrates an example of timing synchronization status request in accordance with embodiments of the present disclosure

[0032] Figure 7 illustrates a timing synchronization status report procedure in accordance with embodiments of the present disclosure;

[0033] Figure 8 illustrates a procedure for deactivation of timing synchronization status reporting in accordance with embodiments of the present disclosure;

[0034] Figure 9 illustrates a new service operation to enable TSCTSF to modify a nonUeN2Info subscription in accordance with an embodiment of the present disclosure;

[0035] Figure 10 illustrates an improvement to alternative 2 of Figure 2 in accordance with an embodiment of the present disclosure;

[0036] Figure 11 illustrates a procedure for handling the failure scenario in accordance with one embodiment of the present disclosure;

[0037] Figure 12 illustrates a procedure for handling the failure scenario in accordance with another embodiment of the present disclosure;

[0038] Figures 13, 14, and 15 are schematic block diagrams of example embodiments of a network node.Detailed Description

[0039] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0040] Radio Node: As used herein, a "radio node" is either a radio access node or a wireless communication device.

[0041] Radio Access Node: As used herein, a "radio access node" or "radio network node" or "radio access network node" is any node in a Radio Access Network (RAN) of a cellular communications network that operates to wirelessly transmit and / or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolvedNode B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), a relay node, a network node that implements part of the functionality of a base station (e.g., a network node that implements a gNB Central Unit (gNB-CU) or a network node that implements a gNB Distributed Unit (gNB-DU)) or a network node that implements part of the functionality of some other type of radio access node.

[0042] Core Network Node: As used herein, a "core network node" is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing an Access and Mobility Management Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.

[0043] Communication Device: As used herein, a "communication device" is any type of device that has access to an access network. Some examples of a communication device include, but are not limited to: mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or Personal Computer (PC). The communication device may be a portable, hand-held, computer-comprised, or vehiclemounted mobile device, enabled to communicate voice and / or data via a wireless or wireline connection.

[0044] Wireless Communication Device: One type of communication device is a wireless communication device, which may be any type of wireless device that has access to (i.e., is served by) a wireless network (e.g., a cellular network). Some examples of a wireless communication device include, but are not limited to: a User Equipment device (UE) in a 3GPP network, a Machine Type Communication (MTC) device, and an Internet of Things (loT) device. Such wireless communication devices may be, or may be integrated into, a mobile phone, smart phone, sensor device, meter,vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or PC. The wireless communication device may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and / or data via a wireless connection.

[0045] Network Node: As used herein, a "network node" is any node that is either part of the RAN or the core network of a cellular communications network / system.

[0046] Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system.

[0047] Note that, in the description herein, reference may be made to the term "cell"; however, particularly with respect to 5G NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.

[0048] There currently exist certain challenge(s) with existing technology. Embodiments herein describe solution for overcoming the challenges. The embodiments are described based on the 3GPP 5G system, however it will be apparent to a person skilled in the art that the solution is applicable to any system supporting timing synchronization such as 3GPP 6G systems or even 7G that use similar or equivalent network functions as in the example embodiments of this disclosure.

[0049] There are two main issues with alternative 1 and alternative 2 described in the background.

[0050] Issue 1 (corresponding to Alternative 1 above): In this alternative, the TSCTSF includes NGAP Message "TIMING SYNCHRONISATION STATUS REQUEST" as a N2 container included in the Namf_Communication_NonUeN2MessageTransfer Request message, so that the AMF transparently forwards the request to NG-RAN node, following the existing principle and procedure. There is a problem with the current NGAP message design, which is as follows per clause 9.2.yy.l of R3-238135:TIMING SYNCHRONISATION STATUS REQUESTThis message is sent by the AMF to request the NG-RAN node to start or stop reporting of RAN timing synchronization status information. Direction: AMF NG-RAN node

[0051] The NG-RAN has no knowledge about which TSCTSFs have requested to activate Timing Synchronization Status Reporting. Upon deactivation from one of the subscribed TSCTSFs, the NG-RAN may accidently deactivate Timing Synchronization Status Reporting while the rest of the subscribed TSCTSFs still need to be updated with Timing Synchronization Status Reporting.

[0052] Furthermore, to be future-proof, different TSCTSFs configured for different network slices (e.g., for different Single Network Slice Assistance Informations (S- NSSAIs)) may have different conditions for such Timing Synchronization Status Reporting. For instance, for some network slices, a corresponding TSCTSF could set a threshold of "Clock Accuracy" attribute to 700 microseconds (jis), while for another network slice the corresponding TSCTSF could set a threshold of "Clock Accuracy" to 1000 |is. Similarly, for some network slices a TSCTSF could use (in addition or separate) "Traceable to GNSS" or ' raceable to UTC" as a threshold for RAN TSS reporting, i.e., RAN performs TSS reporting when the time source of the NG-RAN node loses the traceability to Global Navigation Satellite System (GNSS) / Coordinated Universal Time (UTC). In the same way, possible values of other TSS attributes could be used by TSCTSF to formulate the desired thresholds triggering RAN Timing Synchronization Status reporting to a core network.

[0053] Issue 2 (corresponding to Alternative 2 Above): When differentTSCTSFs configured for different network slices (S-NSSAI) may have different conditions for such Timing Synchronization Status Reporting, different TSCTSFs should be able to include their own conditions in theNamf_Communication_NonUeN2InfoSubscribe request, so that the AMF shouldcreate the corresponding NGAP "TIMING SYNCHRONISATION STATUS REQUEST" separately even to the SAME NG-RAN.

[0054] Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges.

[0055] Solution 1 (enhanced version of Alternative 1 above): The TSCTSF includes a NGAP Message "TIMING SYNCHRONISATION STATUS REQUEST" as a N2 container included in the Namf_Communication_NonUeN2MessageTransfer Request message to the AMF, so that the AMF transparently forwards the NGAP message to the concerning NG-RAN nodes.• To support the scenario where multiple TSCTSFs are deployed, the TIMING SYNCHRONISATION STATUS REQUEST contains a correlation identifier, to identify the requester of the intended TSS reports, e.g. the TSCTSF Network Function (NF) Identity (ID) (which can be encoded in the Routing ID) of the TSCTSF, which is sending the request for START or STOP, or a Report ID (corresponding to each of TSS report control information). Upon receiving such request, the NG-RAN stores such information and knows if multiple TSCTSFs have requested activation of TIMING SYNCHRONISATION STATUS report. Therefore, when doing deactivation, the NG-RAN keeps the TIMING SYNCHRONISATION STATUS active as long as there is at least one (subscribed) TSCTSF left that still requires timing synchronization status reporting.• Furthermore, to be future-proof, different TSCTSFs configured for different network slices may have different conditions for the TSS reports, e.g. thresholds for the NG-RAN to trigger to generate such a status report, or a time condition where the NG-RAN only reports for a specific period. In this case, TSCTSF sets one or more thresholds using TSS attributes from Table 5.27.1.12-1 ofTS 23.501, whereas a time condition can be set also by TSCTSF using one or more Temporal Validity Conditions that may be included by AF as a part of request for ASTI and / or (g)PTP services. These conditions can be included in a TSS Report Control Information. Each TSS Report Control Information includes a Report ID to allow correlation.• At the message level of the NGAP messages "TIMING SYNCHRONISATION STATUS REPORT ", the NG-RAN includes one or more correlation id(s) (which were included in the "TIMING SYNCHRONISATION STATUS REQUEST") toidentify the intended receivers, so that the AMF will forward the report only to the TSCTSF(s) (as identified by the Routing Id), and each RAN Timing Synchronization Status Information Item contains the corresponding Report Id to allow TSCTSF to correlate the reports for different network slices when the TSCTSF supports multiple network slices.• A TSCTSF supporting multiple network slices may send a list of TSS reporting control information in one TIMING SYNCHRONISATION STATUS REQUEST, including Report ID, Slicing ID, thresholds values, validity Timers.• To be able to handle threshold values e.g. per S-NSSAI for the same TSCTSF node, in one embodiment, TSS attributes thresholds values are signalled to NG- RAN node, to indicate the NG-RAN node should perform TSS report based on per TSS report control information.• A gNodeB (gNB)-Control Unit (CU) can forward the TSS report control information to gNB-Distributed Unit (DU). gNB-DU includes the correlation id in the TSS report to gNB-CU.• gNB-CU may collect and evaluate the TSS request, and only send one request to gNB-DU. The request from the gNB-CU may ask the gNB-DU to perform periodic reporting, or report when the thresholds values are met, i.e. gNB-DU may not necessarily be aware of the NF ID / Report ID. Upon the reception of the TSS reporting, gNB-CU determines to which AF ID / Report ID to be included in the TSS report towards the Core Network (CN).• So far, 3GPP has only considered START or STOP TSS Reporting in a NG-RAN. The present disclosure introduces more precise TSS reporting control which is per network slice with its own threshold and / or time periods; therefore, a modification of such TSS reporting control is added and / or a new NGAP message or a new enumeration value "Modify" is added in the TIMING SYNCHRONISATION STATUS REQUEST.

[0056] In an example embodiment, one or more of the following information elements are added in the TIMING SYNCHRONISATION STATUS REQUEST, where these information elements may be grouped into a new information element, preferably called, "TSS Control Information":1. Correlation Id which contains the ID which is allocated by the NF consumer (i.e., TSCTSF) to identify the TSS Control Information and the corresponding generated reports;2. S-NSSAI may be included to indicate the network slice of which the TSS to measure;3. Threshold(s) for each TSS attribute (from Table 5.27.1.12-1 of TS 23.501 [5]) may be included to contain the thresholds provisioned to NG-RAN node(s) by the TSCTSF to trigger NG-RAN node(s) to generate a Time Synchronization Status report towards the core network, e.g., Clock Accuracy;4. Validity Time may be included by TSCTSF to instruct the NG-RAN to trigger a report only when the validity time is matched. A Validity Time may be determined by the CN function, e.g. TSCTSF or AMF based on a set of "Temporal Validity Condition" if / when included by the AF inside the request(s) for ASTI or (g)PTP services.

[0057] In one embodiment, one or more of the following information elements are added in the TIMING SYNCHRONISATION STATUS REPORT:1. Correlation ID, e.g. Report ID2. Routing ID shall be included to contain TSCTSF NF Instance ID;

[0058] The handling of multiple of the same TSS report requests in NG-RAN node is specified.

[0059] Solution 2 (corresponding to an enhancement to Alternative 2 described above): Different TSCTSFs configured for different network slices (S- NSSAI) may have different conditions for such Timing Synchronization Status Reporting, i.e. different TSCTSFs should be able to include their own TSS report control information in the Namf_Communication_NonUeN2InfoSubscribe request, so that the AMF creates the corresponding NGAP "TIMING SYNCHRONISATION STATUS REQUEST" message separately even to the SAME NG-RAN. Alternatively, the AMF can aggregate such requests from different TSCTSF into one NGAP message TIMING SYNCHRONISATION STATUS REQUEST.

[0060] A TSCTSF supporting multiple network slices may send a list of TSS reporting control information in one Namf_Communication_NonUeN2InfoSubscribe request.

[0061] A TSCTSF may send a Patch request to modify the subscription for Namf_Communication_NonUeN2InfoSubscribe, e.g. for TssControlInformation.

[0062] Corresponding handling in NG-RAN node shall be specified, if multiple TSS report requests are received from the same CN (e.g., AMF) node.

[0063] Certain embodiments may provide one or more of the following technical advantage(s). The solution to support the TIMING SYNCHRONISATION STATUS Report procedure is made future-proof, to support one or more TSCTSFs requesting TSS reporting with different thresholds and / or validityTimer.

[0064] Figure 3 illustrates one example of a cellular communications system 300 in which embodiments of the present disclosure may be implemented. In the embodiments described herein, the cellular communications system 300 is a 5G system (5GS) including a Next Generation RAN (NG-RAN) and a 5G Core (5GC); however, the embodiments described herein are not limited to the 5GS and may be used in other similar systems (e.g., a future 6G system). In this example, the RAN includes base stations 302-1 and 302-2, which in the 5GS include NR base stations (gNBs) and optionally next generation eNBs (ng-eNBs) (e.g., LTE RAN nodes connected to the 5GC), controlling corresponding (macro) cells 304-1 and 304-2. The base stations 302- 1 and 302-2 are generally referred to herein collectively as base stations 302 and individually as base station 302. Likewise, the (macro) cells 304-1 and 304-2 are generally referred to herein collectively as (macro) cells 304 and individually as (macro) cell 304. The RAN may also include a number of low power nodes 306-1 through 306-4 controlling corresponding small cells 308-1 through 308-4. The low power nodes 306-1 through 306-4 can be small base stations (such as pico or femto base stations) or RRHs, or the like. Notably, while not illustrated, one or more of the small cells 308-1 through 308-4 may alternatively be provided by the base stations 302. The low power nodes 306-1 through 306-4 are generally referred to herein collectively as low power nodes 306 and individually as low power node 306. Likewise, the small cells 308-1 through 308-4 are generally referred to herein collectively as small cells 308 and individually as small cell 308. The cellular communications system 300 also includes a core network 310, which in the 5G System (5GS) is referred to as the 5GC. The base stations 302 (and optionally the low power nodes 306) are connected to the core network 310.

[0065] The base stations 302 and the low power nodes 306 provide service to wireless communication devices 312-1 through 312-5 in the corresponding cells 304 and308. The wireless communication devices 312-1 through 312-5 are generally referred to herein collectively as wireless communication devices 312 and individually as wireless communication device 312. In the following description, the wireless communication devices 312 are oftentimes UEs, but the present disclosure is not limited thereto.

[0066] Figure 4 illustrates a wireless communication system represented as a 5G network architecture composed of core Network Functions (NFs), where interaction between any two NFs is represented by a point-to-point reference point / interface. Figure 4 can be viewed as one particular implementation of the system 300 of Figure 3.

[0067] Seen from the access side the 5G network architecture shown in Figure 4 comprises a plurality of UEs 312 connected to either a RAN 302 or an Access Network (AN) as well as an AMF 400. Typically, the R(AN) 302 comprises base stations, e.g. such as eNBs or gNBs or similar. Seen from the core network side, the 5GC NFs shown in Figure 4 include a NSSF 402, an AUSF 404, a UDM 406, the AMF 400, a SMF 408, a PCF 410, and an Application Function (AF) 412.

[0068] Reference point representations of the 5G network architecture are used to develop detailed call flows in the normative standardization. The N1 reference point is defined to carry signaling between the UE 312 and AMF 400. The reference points for connecting between the AN 302 and AMF 400 and between the AN 302 and UPF 414 are defined as N2 and N3, respectively. There is a reference point, Nil, between the AMF 400 and SMF 408, which implies that the SMF 408 is at least partly controlled by the AMF 400. N4 is used by the SMF 408 and UPF 414 so that the UPF 414 can be set using the control signal generated by the SMF 408, and the UPF 414 can report its state to the SMF 408. N9 is the reference point for the connection between different UPFs 414, and N14 is the reference point connecting between different AMFs 400, respectively. N15 and N7 are defined since the PCF 410 applies policy to the AMF 400 and SMF 408, respectively. N12 is required for the AMF 400 to perform authentication of the UE 312. N8 and N10 are defined because the subscription data of the UE 312 is required for the AMF 400 and SMF 408.

[0069] The 5GC network aims at separating UP and CP. The UP carries user traffic while the CP carries signaling in the network. In Figure 4, the UPF 414 is in the UP and all other NFs, i.e., the AMF 400, SMF 408, PCF 410, AF 412, NSSF 402, AUSF 404, and UDM 406, are in the CP. Separating the UP and CP guarantees each plane resource to be scaled independently. It also allows UPFs to be deployed separately from CPfunctions in a distributed fashion. In this architecture, UPFs may be deployed very close to UEs to shorten the Round Trip Time (RTT) between UEs and data network for some applications requiring low latency.

[0070] The core 5G network architecture is composed of modularized functions. For example, the AMF 400 and SMF 408 are independent functions in the CP. Separated AMF 400 and SMF 408 allow independent evolution and scaling. Other CP functions like the PCF 410 and AUSF 404 can be separated as shown in Figure 4. Modularized function design enables the 5GC network to support various services flexibly.

[0071] Each NF interacts with another NF directly. It is possible to use intermediate functions to route messages from one NF to another NF. In the CP, a set of interactions between two NFs is defined as service so that its reuse is possible. This service enables support for modularity. The UP supports interactions such as forwarding operations between different UPFs.

[0072] Figure 5 illustrates a 5G network architecture using service-based interfaces between the NFs in the CP, instead of the point-to-point reference points / interfaces used in the 5G network architecture of Figure 4. However, the NFs described above with reference to Figure 4 correspond to the NFs shown in Figure 5. The service(s) etc. that a NF provides to other authorized NFs can be exposed to the authorized NFs through the service-based interface. In Figure 5 the service based interfaces are indicated by the letter "N" followed by the name of the NF, e.g. Namf for the service based interface of the AMF 400 and Nsmf for the service based interface of the SMF 408, etc. The NEF 500 and the NRF 502 in Figure 5 are not shown in Figure 4 discussed above. However, it should be clarified that all NFs depicted in Figure 4 can interact with the NEF 500 and the NRF 502 of Figure 5 as necessary, though not explicitly indicated in Figure 4.

[0073] Some properties of the NFs shown in Figures 4 and 5 may be described in the following manner. The AMF 400 provides UE-based authentication, authorization, mobility management, etc. A UE 312 even using multiple access technologies is basically connected to a single AMF 400 because the AMF 400 is independent of the access technologies. The SMF 408 is responsible for session management and allocates Internet Protocol (IP) addresses to UEs. It also selects and controls the UPF 414 for data transfer. If a UE 312 has multiple sessions, different SMFs 408 may be allocated to each session to manage them individually and possibly provide differentfunctionalities per session. The AF 412 provides information on the packet flow to the PCF 410 responsible for policy control in order to support QoS. Based on the information, the PCF 410 determines policies about mobility and session management to make the AMF 400 and SMF 408 operate properly. The AUSF 404 supports authentication function for UEs or similar and thus stores data for authentication of UEs or similar while the UDM 406 stores subscription data of the UE 312. The Data Network (DN), not part of the 5GC network, provides Internet access or operator services and similar.

[0074] An NF may be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure.

[0075] Now, the description turns to details of embodiments of the present disclosure.

[0076] Solution 1 (enhanced version of Alternative 1 above): Figure 6 illustrates a timing synchronization status procedure in accordance with an embodiment of the present disclosure. This procedure involves an AMF 600 and an NG-RAN node 602. As illustrated, the AMF 600 sends, to the NG-RAN node 602, a timing synchronization status request (step 604). In one embodiment, the timing synchronization status request includes one or more of the following information elements, where these information elements may, for example, be grouped into a new information element, preferably called, "TSS Control Information":• Correlation ID which contains an ID which is allocated by the NF consumer (i.e., TSCTSF) to identify the TSS Control Information and the corresponding generated TSS reports;• S-NSSAI may be included to indicate the network slice of which the TSS is to measure;• threshold(s) for one or more TSS attributes (e.g., one or more of the TSS attributes from Table 5.27.1.12-1 of TS 23.501) may be included in the timing synchronization status request to contain the thresholds provisioned to NG-RAN node(s) by the TSCTSF to trigger NG-RAN node(s) to generate a Time Synchronization Status report towards the core network, e.g., Clock Accuracy;• Validity Time may be included by TSCTSF to instruct the NG-RAN to trigger a report only when the validity time is matched. A Validity Time may be determined by the CN function, e.g. TSCTSF or AMF based on a set of "Temporal Validity Condition" if / when included by the AF inside the request(s) for ASTI or (g)PTP services,

[0077] The NG-RAN node 602 sends, to the AMF 600, a timing synchronization status response (step 606).

[0078] One example embodiment of the timing synchronization status request of step 604 of Figure 6 is as follows:9.2.yy.l TIMING SYNCHRONISATION STATUS REQUESTThis message is sent by the AMF to request the NG-RAN node to start or stop reporting of RAN timing synchronization status information.Direction:nodeValidity Time

[0079] Figure 7 illustrates a timing synchronization status report procedure in accordance with an embodiment of the present disclosure. This procedure involves an AMF 700 and an NG-RAN node 702, which may be the same as the AMF 600 and the NG-RAN node 602 of Figure 6. As illustrated, the NG-RAN node 702 sends, to the AMF 700, a timing synchronization status report (step 704). In one embodiment, the timing synchronization status report includes one or more of the following information elements, • Correlation ID, e.g. Report ID• Routing ID containing the TSCTSF NF Instance ID.

[0080] One example embodiment of the timing synchronization status report of step 704 of Figure 7 is as follows: 9.2.yy.4 TIMING SYNCHRONISATION STATUS REPORTThis message is sent by the NG-RAN node to report previously requested RAN timing synchronization status information.Direction: NG-RAN node

[0081] Alternatively, the "RAN Timing Synchronization Status Information" IE is modified to contain detailed information.

[0082] The message may contain in the report a list of "Routing IDs" and / or "Report IDs".

[0083] One example embodiment of an alternative for the timing synchronization status report of step 704 of Figure 7 is as follows:9.2.yy.4 Alternative implementation example for TIMING SYNCHRONISATION STATUS REPORT, one report per requested NF.Direction: NG-RAN node

[0084] Similar solutions may be provided for F1AP for the TSS request sending from gNB-CU to gNB-DU, and the TSS report sending from gNB-DU to gNB-CU.

[0085] If there are "threshold values" for the TSS reporting included in the message from CN to NG-RAN node, it is specified in NGAP TS 38.413 that the NG-RAN node shall stop the existing reporting, and start with the new TSS report. Alternatively, it is specified that the new reporting is added on, NG-RAN node shall report based on theexisting and the new thresholds values. F1AP is impacted to be able to handle multiple "thresholds". Alternative is to include a new code point in the below

[0086] Figure 8 illustrates a procedure for deactivation of timing synchronization status reporting in accordance with an embodiment of the present disclosure. This procedure involves a NG-RAN node 800 and an AMF 802, which may be the same as the NG-RAN node 602 of Figure 6 and the AMF 600 of Figure 6. As illustrated, the NG-RAN node 800 receives, from the AMF 802, a request to stop timing synchronization status reporting, e.g., for a particular NF consumer (e.g., a particular TSCTSF) (step 804). In one embodiment, this request includes a correlation ID or report ID and optionally a network sliced indicator (e.g., S-NSSAI) included in the request. The NG-RAN node 800 determines whether there are any other NF consumers (e.g., other TSCTSFs) for which timing synchronization status reporting is still active (step 806). The NG-RAN node 800 deactivates timing synchronization status reporting if there are no other consumer NFs for which timing synchronization status reporting is still active and otherwise refraining from deactivating timing synchronization status reporting (step 808).

[0087] Solution 2:

[0088] At the CN (e.g., AMF) node: The following additional changes to the Namf_Communication service are provided in addition to the above changes to NGAP (introduced for solution 1)

[0089] 1. The following attributes is added in the data type NonUeN2InfoSubscriptionCreateData:6.1.6.2.10Type: NonUeN2InfoSubscriptionCreateDataTable 6.1.6.2.10-1: Definition of type NonlleN2InfoSubscriptionCreateData

[0090] 2. New data types:6.1.6.2.X Type: TssControlInformation Table 6.1.6.2.X-1: Definition of type TssControlInformation6.1.6.2.Y Type: TssThresholdsTable 6.1.6.2.Y-1: Definition of type TssThresholds6.1.6.2.Z Type: ClockAccuracyTable 6.1.6.2.Y-1: Definition of type ClockAccuracy

[0091] 3. A new service operation to enable TSCTSF to modify a nonUeN2Info subscription. In this regard, Figure 9 illustrates one example of this new service operation. As illustrated in Figure 9, the NF service consumer (e.g., TSCTSF) sends, to the UPF, a request to modify a nonUeN2Info subscription in step 1. This request includes a n2NotifySubscriptionId and data indicative of one or more requested modifications of the corresponding nonUeN2Info subscription. The UPF may thenrespond with a 204 No Content (step 2a), a 200 OK (step 2b), or problem details (step 2c).

[0092] Figure 10 illustrates one example embodiment of Solution 2. As illustrated, the process of Figure 10 involves a NF consumer 1000 (e.g., TSCTSF), a core network node 1002 (e.g., AMF), and a RAN node 1004 (e.g., NG-RAN node). As illustrated, the NF consumer 1000 sends a non-UE N2 information subscription request to the core network node 1002 (step 1006). As described above, the non-UE N2 information subscription request includes TSS control information for TSS reporting. The details above regarding this TSS control information are equally applicable here. The core network node 1002 sends a timing synchronization status request to the RAN node 1004 (step 1008). The timing synchronization status request includes the TSS control information from the subscription request of step 1006. Note that, as described above, separate timing synchronization status requests including their own respective TSS control information may be sent by the core network node 1002 to the same RAN node 1004, or the core network node 1002 may aggregate multiple such requests into a single timing synchronization status request to the RAN node 1004. The RAN node sends a timing synchronization status response to the core network node 1002 (step 1010). While not shown, the RAN node 1004 generates and sends TSS report(s) in accordance with the timing synchronization status request.

[0093] Other Embodiments on NG-RAN node:

[0094] At the NG-RAN node when multiple TSS report requests TIMING SYNCHRONISATION STATUS REQUEST are sent by CN without Routing ID, it is specified in NGAP TS 38.413.

[0095] One embodiment: The NG-RAN node, upon reception of the second TSS reporting start request, ignores the new start request, and proceeds with the existing TSS reporting. The "TIMING SYNCHRONISATION STATUS RESPONSE" is sent back to AMF. Alternatively, it is specified that NG-RAN node consider the subsequent start request is not needed and report failure. The existing report is maintained in NG-RAN node.

[0096] Another embodiment: The NG-RAN node stores the information of the numbers when "start" and "stop" requests are received and keeps the counting. Only when "Number-of-Stop-request == Number-of-Start-request", the TSS reporting in the NG-RAN node is stopped.

[0097] Another embodiment: If "thresholds values" for the TSS reporting are included in the message from CN to NG-RAN node, the NG-RAN node stops the existing reporting, and starts with the new TSS report. Alternatively, the new reporting is added on such that the NG-RAN node reports based on the existing and the new thresholds values. F1AP is enhanced to be able to handle multiple "thresholds".Handling of Failure Scenario

[0098] When comes to handling the failure scenario, e.g. when one or more NG- RANs fail to activate the time synchronization status report, for alternative 2, the AMF needs to generate an N2 container encapsulating TIMING SYNCHRONISATION STATUS FAILURE in the Namf_Communication_NonUeN2InfoNotify request message towards the TSCTSF, while be noted that the TIMING SYNCHRONISATION STATUS Request message was not included by the TSCTSF, or theNamf_Communication_NonUeN2InfoNotify request message needs to be enhanced to carry an NGAP cause per NG-RAN Id (which is included in the TIMING SYNCHRONISATION STATUS FAILURE).

[0099] When at least one of the NG-RAN nodes has failed to start TSS reporting, that NG-RAN node will respond with a TIMING SYNCHRONISATION STATUS FAILURE message. Such failure information is propagated to the TSCTSF, so that, the TSCTSF may• re-attempt the same procedure after an operator configurable timer, e.g. when the failure is due to a temporary reason, e.g. overload in the NG-RAN, so after the timer expires, the TSCTSF re-sends TIMING SYNCHRONISATION STATUS request message to start the TSS in this specific NG-RAN(s);• generate an alarm to the Operations and Maintenance (O&M) system; and• determine to deactivate the AF-requested time synchronization service or keep it activated without enabled timing synchronization status monitoring; such determination may be performed based on the local configuration or operator policy, e.g. after several reattempts of the start of the reporting for Timing Synchronization Status in said NG-RANs.To do so, the TSCTSF needs to know exactly which NG-RAN node has failed to initiate RAN timing synchronization status reporting.

[0100] In this regard, in one embodiment, an identifier is added in an appropriate failure message that identifies the NG-RAN node that has failed to initiate the RAN timing synchronization status reporting. Two exemplary embodiments are described below with respect to Figures 11 and 12.

[0101] Figure 11 illustrates a procedure for handling the failure scenario in accordance with one embodiment of the present disclosure. This procedure involves a RAN node 1100 (e.g., NG-RAN node), an CN node 1102 (e.g., AMF), and a NF consumer 1104 (e.g., TSCTSF). As illustrated, in the failure scenario, the RAN node 1100 (that has failed to initiate RAN timing synchronization reporting) includes its RAN ID (e.g., NG-RAN ID) or a RAN TSS Scope (e.g., the RAN TSS Scope includes the RAN ID and also information about an area that the RAN node 1100 is serving, see example below) in a TIMING SYNCHRONISATION STATUS FAILURE message sent to the CN node 1102 (step 1106). In this example, the CN node 1102 transparently forwards the NGAP message "TIMING SYNCHRONISATION STATUS FAILURE" as an N2 container to the NF consumer 1104 (step 1108). In other words, in one embodiment, the CN node 1102 is the AMF, and in step 1108 the AMF sends, to the NF consumer 1104 (e.g., TSCTSF) a message containing at least an N2 container encapsulating the TIMINGSYNCH RONZIATION STATUS FAILURE message of step 1106. The message of step 1108 may be, for example, a Namf_Communication-NonUeN2Message Transfer response or a Namf_Communication_NonUeN2InfoNotify request message.

[0102] One example embodiment of the TIMING SYNCHRONISATION STATUS FAILURE message of Figure 11 is shown below:9.2.18.3 TIMING SYNCHRONISATION STATUS FAILUREThis message is sent by the NG-RAN node to indicate that reporting of RAN timing synchronisation status information cannot be initiated.Direction: NG-RAN node —>AMF9.3.1.254 RAN TSS ScopeThis IE indicates the scope of the RAN timing synchronisation status as defined in TS 23.501 [9].

[0103] Figure 12 illustrates a procedure for handling the failure scenario in accordance with another embodiment of the present disclosure. This procedure involves a RAN node 1200 (e.g., a NG-RAN node), an CN node 1202 (e.g., an AMF), and a NF consumer 1204 (e.g., TSCTSF). As illustrated, in the failure scenario, the RAN node 1200 (that has failed to initiate RAN timing synchronization reporting) sends a TIMING SYNCHRONISATION STATUS FAILURE message to the CN node 1202 (step 1206). In this example, the TIMING SYNCHRONISATION STATUS FAILURE message may not include the RAN ID (e.g., NG RAN ID) or TSS scope of the RAN node 1200. The CN node 1202 sends a message (e.g., Namf_Communication_NonUeN2MessageTransfer response or Namf_Communication_NonUeN2InfoSubscribe response message and / or Namf_Communication_NonUeN2InfoNotify Request message) to the NF consumer 1204, where this message includes or is provided together with the RAN ID (or a RAN TSSScope which may include, e.g., the NG-RAN ID and also information about an area that the RAN node is serving, e.g., similar to example above) of the RAN node 1200 (step 1208). Thus, in other words, the CN node 1202 adds the RAN ID (of the RAN node 1200 sending the TIMING SYNCHRONISATION STATUS FAILURE message), e.g., in the Namf_Communication_NonUeN2MessageTransfer response or Namf_Communication_NonUeN2InfoSubscribe response message and / or Namf_Communication_NonUeN2InfoNotify Request message, together with or without a N2 container encapsulating TIMING SYNCHRONISATION STATUS FAILURE message. Note that, for the embodiment of Figure 11, there will be an N2 container encapsulating TIMING SYNCHRONISATION STATUS FAILURE message containing the NG-RAN Id and / or RAN TSS SCOPE, whereas, for the embodiment of Figure 12, the CN node 1202 will generate such failure information if the N2 Container encapsulating TIMING SYNCHRONISATION STATUS FAILURE message is not included, and add the NG-RAN Id and / or RAN TSS SCOPE on its own (regardless of if the N2 Container encapsulating TIMING SYNCHRONISATION STATUS FAILURE message is included or not) in the Namf_Communication_NonUeN2MessageTransfer response or Namf_Communication_NonUeN2InfoSubscribe response or notification request message.Further Description

[0104] Figure 13 is a schematic block diagram of a network node 1300 according to some embodiments of the present disclosure. Optional features are represented by dashed boxes. The network node 1300 may be, for example, a base station 302 or 306, a NG-RAN node (e.g., NG-RAN node 602, 702, 1100, or 1200), or a network node that implements all or part of the functionality of the base station 302 or NG-RAN node described herein. Alternatively, the network node 1300 may be a core network node such as, e.g., an AMF, TSCTSF, or the like. As illustrated, the network node 1300 includes a control system 1302 that includes one or more processors 1304 (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and / or the like), memory 1306, and a network interface 1308. The one or more processors 1304 are also referred to herein as processing circuitry. In addition, if the network node 1300 is a RAN node (e.g., a base station 302, NG-RAN node, or network node that implements at least some of thefunctionality of the base station 302 or NG-RAN node), the network node 1300 may include one or more radio units 1310 that each includes one or more transmitters 1312 and one or more receivers 1314 coupled to one or more antennas 1316. The radio units 1310 may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s) 1310 is external to the control system 1302 and connected to the control system 1302 via, e.g., a wired connection (e.g., an optical cable). However, in some other embodiments, the radio unit(s) 1310 and potentially the antenna(s) 1316 are integrated together with the control system 1302. The one or more processors 1304 operate to provide one or more functions of the network node 1300 as described herein (e.g., one or more functions of a base station 302 or NG-RAN node described herein). In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory 1306 and executed by the one or more processors 1304.

[0105] Figure 14 is a schematic block diagram that illustrates a virtualized embodiment of the network node 1300 according to some embodiments of the present disclosure. Again, optional features are represented by dashed boxes. As used herein, a "virtualized" network node is an implementation of the network node 1300 in which at least a portion of the functionality of the network node 1300 is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, if the network node 1300 is a RAN node, the network node 1300 may include the control system 1302 and / or the one or more radio units 1310, as described above. The control system 1302 may be connected to the radio unit(s) 1310 via, for example, an optical cable or the like. The network node 1300 includes one or more processing nodes 1400 coupled to or included as part of a network(s) 1402. If present, the control system 1302 or the radio unit(s) are connected to the processing node(s) 1400 via the network 1402. Each processing node 1400 includes one or more processors 1404 (e.g., CPUs, ASICs, FPGAs, and / or the like), memory 1406, and a network interface 1408.

[0106] In this example, functions 1410 of the network node 1300 described herein (e.g., one or more functions of a base station 302, NG-RAN node, AMF, TSCTSF, etc. described herein) are implemented at the one or more processing nodes 1400 or distributed across the one or more processing nodes 1400 and the control system 1302 and / or the radio unit(s) 1310 in any desired manner. In some particular embodiments,some or all of the functions 1410 of the network node 1300 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environ ment(s) hosted by the processing node(s) 1400. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) 1400 and the control system 1302 is used in order to carry out at least some of the desired functions 1410. Notably, in some embodiments, the control system 1302 may not be included, in which case the radio unit(s) 1310 communicates directly with the processing node(s) 1400 via an appropriate network interface(s).

[0107] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the network node 1300 or a node (e.g., a processing node 1400) implementing one or more of the functions 1410 of the network node 1300 in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0108] Figure 15 is a schematic block diagram of the network node 1300 according to some other embodiments of the present disclosure. The network node 1300 includes one or more modules 1500, each of which is implemented in software. The module(s) 1500 provides the functionality of the network node 1300 described herein. This discussion is equally applicable to the processing node 1400 of Figure 14 where the modules 1500 may be implemented at one of the processing nodes 1400 or distributed across multiple processing nodes 1400 and / or distributed across the processing node(s) 1400 and the control system 1302.

[0109] Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to executeprogram code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and / or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according to one or more embodiments of the present disclosure.

[0110] While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).

[0111] Some example embodiments of the present disclosure, but not limited thereto, are as follows:Embodiment 1. A method performed by a core network node (e.g., AMF or NF consumer (e.g., TSCTSF)), the method comprising: sending (604) a timing synchronization status reporting control information to a Radio Access Network, RAN, node, the timing synchronization status reporting control information comprising any one or more of the following information elements: a correlation identity, ID, that identifies a requestor of corresponding TSS reports; an identifier of a network slice for which the timing synchronization status reporting control information applies; one or more thresholds for one or more TSS attributes provisioned to the RAN node (e.g., by a corresponding NF consumer such as, e.g., TSCTSF) to trigger the RAN node to generate a TSS report towards the core network; a validity time for the timing synchronization status reporting control information.Embodiment 2. The method of embodiment 1, wherein: the timing synchronization status reporting control information is included in an NGAP message "timing synchronization status request" encoded by the TSCTSF (which will be included in the Namf_communication_nonUeN2MessageTransfer Request as a N2 Container) where the AMF transparently forward it to the NG-RAN); the timing synchronization status reporting control information is included in Namf_communication_nonUeN2InfoSubscribe Request at message level to instruct the AMF to generate the timing synchronization status request to the relevant NG-RANs with the said timing synchronization status reporting control information.Embodiment 3. The method of embodiment 1 or 2, wherein the correlation ID is encoded as a routing ID which contains an NF ID of the requestor (i.e., a consumer NF such as, e.g., a TSCTSF).Embodiment 4. The method of embodiment 3, wherein the correlation ID further comprises a report ID that correlates between a given TSS report and the timing synchronization status reporting control information.Embodiment 5. The method of any of embodiments 1 to 4, further comprising receiving a timing synchronization status report from the RAN node, the timing synchronization status report being in accordance with the timing synchronization status reporting control information.Embodiment 6. The method of any of embodiments 1 to 5, wherein the timing synchronization status reporting control information comprises timing synchronization status reporting control information for one or more (e.g., two or more) network slices, and, for each network slice of the one or more network slices, the timing synchronization status reporting control information for the network slice comprises any one or more of the following information elements: a report ID that identifies the report is generated according to the said TSS reporting control information; an identifier of the network slice; one or more thresholds for one or more TSS attributes provisioned to the RAN node (e.g., by a corresponding NF consumer such as, e.g., TSCTSF) to trigger the RAN node to generate a TSS report towards the core network for the network slice; a validity time for the timing synchronization status reporting control information for the network slice.Embodiment 7. A core network node adapted to perform the method of any of embodiments 1 to 6.Embodiment 8. A method performed by a Radio Access Network, RAN, node, the method comprising: receiving (604) timing synchronization status reporting control information from a core network node (e.g., AMF or NF consumer (e.g., TSCTSF)), the timing synchronization status reporting control information comprising any one or more of the following information elements: a correlation identity, ID, that identifies a requestor of corresponding TSS reports;an identifier of a network slice for which the timing synchronization status reporting control information applies; one or more thresholds for one or more TSS attributes provisioned to the RAN node (e.g., by a corresponding NF consumer such as, e.g., TSCTSF) to trigger the RAN node to generate a TSS report towards the core network; a validity time for the timing synchronization status reporting control information.Embodiment 9. The method of embodiment 8, wherein: the timing synchronization status reporting control information is included in an NGAP message "timing synchronization status request" encoded by the TSCTSF (which will be included in the Namf_communication_nonUeN2MessageTransfer Request as a N2 Container) where the AMF transparently forward it to the NG-RAN); the timing synchronization status reporting control information is included in Namf_communication_nonUeN2InfoSubscribe Request at message level to instruct the AMF to generate the timing synchronization status request to the relevant NG-RANs with the said timing synchronization status reporting control information.Embodiment 10. The method of embodiment 8 or 9, wherein the correlation ID is encoded as a routing ID which contains a NF ID of the requestor (i.e., a consumer NF such as, e.g., a TSCTSF).Embodiment 11. The method of embodiment 10, wherein the correlation ID further comprises a report ID that correlates between a given TSS report and the timing synchronization status reporting control information.Embodiment 12. The method of any of embodiments 8 to 11, further comprising sending a timing synchronization status report in accordance with the timing synchronization status reporting control information.Embodiment 13. The method of any of embodiments 8 to 11, further comprising generating (704) one or more TSS status reports in accordance with the timingsynchronization status reporting control information and sending (704) the one or more TSS reports to the requestor indicated by the correlation ID.Embodiment 14. The method of embodiment 13, wherein each of the TSS reports comprises the correlation ID and / or a routing ID containing a NF instance ID of the requestor.Embodiment 15. The method of any of embodiments 8 to 14, further comprising sending (606) a timing synchronization status response to the core network node.Embodiment 16. The method of any of embodiments 8 to 15, wherein the timing synchronization status reporting control information comprises TSS reporting control information for one or more (e.g., two or more) network slices, and, for each network slice of the one or more network slices, the TSS reporting control information for the network slice comprises any one or more of the following information elements: a report ID that identifies the report is generated according to the said TSS reporting control information; an identifier of the network slice; one or more thresholds for one or more TSS attributes provisioned to the RAN node (e.g., by a corresponding NF consumer such as, e.g., TSCTSF) to trigger the RAN node to generate a TSS report towards the core network for the network slice; a validity time for the timing synchronization status request for the network slice.Embodiment 17. The method of any of embodiments 8 to 16, further comprising: receiving (e.g., from a core network node (e.g., AMF) a request to stop timing synchronization status reporting for a particular NF consumer; and determining whether there are any other consumer NFs for which synchronization status reporting is still active; and deactivating synchronization status reporting if there are no other consumer NFs for which synchronization status reporting is still active and otherwise refraining from deactivating synchronization status reporting.Embodiment 18. A RAN node adapted to perform the method of any of embodiments 8 to 17.Embodiment 19. A method in a core network comprising:• at a NF consumer (e.g., TSCTSF) of a timing synchronization status service: o sending (1004) a non-UE N2 information subscription request to a core network node (e.g., AMF), the non-UE N2 information subscription request comprising timing synchronization status, TSS, control information for TSS reporting;• at the core network node: o receiving (1004) the non-UE N2 information subscription request; and o sending (1006) a timing synchronization status request to a RAN node, the timing synchronization status request comprising TSS control information from the non-UE N2 information subscription request.Embodiment 20. The method of embodiment 19, wherein the timing synchronization status request is separate from one or more other timing synchronization status requests sent to the same RAN node, each of the one or more other timing synchronization status requests comprising its own TSS control information.Embodiment 21. The method of embodiment 19, wherein the core network node aggregates two or more non-UE N2 information subscription requests into the timing synchronization status request sent to the RAN node.Embodiment 22. The method of any of embodiments 19 to 21, further comprising, at the NF consumer, sending a request to modify the subscription for the non-UE N2 information.Embodiment 23. A method performed by a Radio Access Network, RAN, node (1100), the method comprising:sending (1106), to a core network node (1102), a timing synchronization failure message comprising information that identifies the RAN node (1100) and / or information that identifies an area served by the RAN node (1100).Embodiment 24. The method of embodiment 23, further comprises receiving a timing synchronization status request message from the core network node (1102), wherein sending (1106) the timing synchronization failure message is responsive to receiving the timing synchronization status request message.Embodiment 25. The method of embodiment 24, wherein the timing synchronization status request message comprises timing synchronization status reporting control information (e.g., in accordance with any of embodiments 8 to 11 or 16.Embodiment 26. A RAN node adapted to perform the method of any of embodiments 23 to 25.Embodiment 27. A method performed by a core network node (1102), the method comprising: receiving (1106), from a RAN node (1100), a timing synchronization failure message comprising information that identifies the RAN node (1100) and / or information that identifies an area served by the RAN node (1100).Embodiment 28. The method of embodiment 27, further comprises sending a timing synchronization status request message to the RAN node (1100), wherein receiving (1106) the timing synchronization failure message is responsive to sending the timing synchronization status request message.Embodiment 29. The method of embodiment 28, wherein the timing synchronization status request message comprises timing synchronization status reporting control information (e.g., in accordance with any of embodiments 1 to 4 or 6.Embodiment 30. The method of any of embodiments 27 to 29, further comprising sending (1108) a message containing (e.g., in a transparent container) the timing synchronization failure message to a NF consumer (1104).Embodiment 31. A core network node adapted to perform the method of any of embodiments 27 to 30.Embodiment 32. A method performed by a core network node (1202), the method comprising: receiving (1206), from a RAN node (1200), a timing synchronization failure message; and sending (1208), to a NF consumer (1204), a message comprising information that identifies the RAN node (1100) from which the timing synchronization failure message was received and / or information that identifies an area served by the RAN node (1100) from which the timing synchronization failure message was received.Embodiment 33. The method of embodiment 32, further comprises sending a timing synchronization status request message to the RAN node (1200), wherein receiving (1206) the timing synchronization failure message is responsive to sending the timing synchronization status request message.Embodiment 34. The method of embodiment 33, wherein the timing synchronization status request message comprises timing synchronization status reporting control information (e.g., in accordance with any of embodiments 1 to 4 or 6.Embodiment 35. A core network node adapted to perform the method of any of embodiments 32 to 34.Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.

Claims

Claims1 . A method performed by a Radio Access Network, RAN, node, the method comprising: receiving (604) timing synchronization status (TSS) reporting control information from a core network node, the timing synchronization status reporting control information comprising any one or more of the following information elements: a routing identifier (ID), that identifies a requestor of corresponding TSS reports; an identifier of a network slice for which the timing synchronization status reporting control information applies; one or more thresholds for one or more TSS attributes provisioned on the RAN node to trigger the RAN node to generate a TSS report towards the core network; or a validity time for the timing synchronization status reporting control information.

2. The method of claim 1 , wherein the timing synchronization status reporting control information is indicated in a timing synchronization status request message transmitted by the core network node.

3. The method of claim 1 or 2, wherein the routing ID indicates a Network Function (NF) ID of the requestor of the TSS reports.

4. The method of claim 3, wherein the NF ID of the requestor is the ID of a Time- Sensitive Communication Time Synchronization Function.

5. The method of any of claims 1 to 4, further comprising sending to the core network node a timing synchronization status report comprising the routing ID comprising the NF ID of the requestor and a RAN TSS scope comprising an identity of the RAN node.

6. The method of claim 2, further comprising sending (606) a timing synchronization status response to the core network node in response to receiving the timing synchronization status request message.

7. A method performed by a Radio Access Network, RAN, node (1100), the method comprising: receiving from a core network node a timing synchronization status (TSS) request message to request TSS reporting, the TSS request message comprising an identification of a requestor of TSS reports; and sending (1106), to the core network node (1102), a timing synchronization failure message to indicate that the RAN node (1100) has failed to initiate RAN timing synchronization reporting.

8. The method of claim 8, wherein the timing synchronization failure message a RAN TSS scope identifying the RAN node.

9. A RAN node adapted to perform the method of any of claims 1 to 8.

10. A RAN node comprising one or more processors and memory comprising instructions which when executed by the one or more processors performing any of the method claims 1 to 8.11 .A method performed by a core network node (1202), the method comprising: receiving (1206), from a RAN node (1200), a timing synchronization failure message; and sending (1208), to a NF consumer (1204), a message comprising information that identifies the RAN node (1100) from which the timing synchronization failure message was received and / or information that identifies an area served by the RAN node (1100) from which the timing synchronization failure message was received.

12. The method of claim 11 , further comprises sending a timing synchronization status request message to the RAN node (1200), wherein receiving (1206) the timing synchronization failure message is responsive to sending the timing synchronization status request message.

13. The method of claim 12, wherein the timing synchronization status request message comprises a routing identifier identifying the identity of the NF consumer.

14. A core network node adapted to perform the method of any of claims 11 to 13.

15. A core network node comprising one or more processors and memory comprising instructions which when executed by the one or more processors performing any of the method claims 11 to 13.

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