Mechanism for Adjusting Seamless Service Continuity to Edge Application Servers during Relocation

Abstract

To provide methods and apparatuses for coordinating seamless service continuity to an Edge Application Server (EAS) at relocation in a cellular communications system.SOLUTION: In a method, an Application Function (AF) sends to a Policy Control Function (PCF) a steering request comprising a keepExistingPSA indication that indicates that a current user plane (UP) path to a current Data Network Access Identifier (DNAI) and to an EAS should be maintained while a new path to a new DNAI and EAS is established. The PCF generates Policy and Charging Control (PCC) rules, and provides the PCC rules to a Session Management Function (SMF). The SMF determines that simultaneous connectivity over the source PSA and the target PSA is to be provided, and configures the target PSA while maintaining the UP connectivity over the source PSA to the current DNAI and to the EAS.SELECTED DRAWING: Figure 4A

Description

Technical Field

[0001] This application claims the benefit of Provisional Patent Application No. 63 / 064,689, filed on August 12, 2020, the disclosure of which is incorporated herein by reference in its entirety.

[0002] This disclosure relates to maintaining service continuity during Edge Application Server (EAS) relocation in a cellular communication system.

Background Art

[0003] This disclosure is related to functions that support Edge Computing (EC) in the 3rd Generation Partnership Project (3GPP®). The 5th Generation (5G) network architecture is defined in 3GPP® Technical Specification (TS) 23.501. The roles of network functions are defined as follows. ● The Session Management Function (SMF) is responsible for session establishment, modification, and release (including selection and control of User Plane Function (UPF) entities), maintains the topology of the associated Packet Data Unit (PDU) session anchor (PSA) UPF, and establishes and releases tunnels between the Access Network (AN) and the UPF, and between UPFs. The SMF also configures traffic forwarding at the UPF. The SMF uses Packet Forwarding Control Protocol (PFCP) procedures to interact with the UPF via the N4 reference point. ● The User Plane Function (UPF) processes user data traffic. Among other functions, the UPF provides an external PDU session point of interconnection to the Data Network (DN) (such as PSA), and performs packet routing and forwarding (e.g., by supporting an Uplink Classifier (UL CL) to route traffic flows to an instance of the DN, and / or by supporting a branching point for supporting multi-homed PDU sessions). ● The Policy Control Function (PCF) supports a unified policy framework for managing the operation of the network. Specifically, the PCF provides policy and charging control (PCC) rules to the Policy and Charging Enforcement Function (PCEF) (i.e., the SMF / UPF that enforces policy and charging decisions according to the provisioned PCC rules). ● The Network Exposure Function (NEF) supports various functions. Specifically, in the context of this disclosure, the NEF functions as an entry point to the operator network, enabling external Application Functions (AFs) (such as content providers) to interact with the 3GPP core network via the NEF. ● The AF sends requests that affect the SMF routing decision of the traffic constituting the PDU session. The AF requests may affect the selection or reselection of the UPF and may enable the routing of user traffic via local access to the DN (identified, for example, by the Data Network Access Identifier (DNAI)). The AF can communicate directly with the PCF within the Service-Based Architecture (SBA) domain or indirectly via the NEF (i.e., use the Application Programming Interface (API) of the NEF that transmits AF communication to the PCF).

[0004] As described in Section 5.13 of 3GPP (Registered Trademark) TS23.501, using EC enables operators and third-party services to be hosted near the access point of the destination User Equipment (UE), reducing end-to-end latency and the load on the transport network and enabling efficient service delivery. The 5G core network selects a UPF close to the UE and performs traffic steering from the UPF to the local DN via the N6 interface. Section 5.13 of TS23.501 also defines many enablers that support EC, either alone or in combination, including the following. ● Selection or reselection of the user plane: As described in section 6.3.3 of TS23.501, the 5G core network selects or reselects a UPF to route user traffic to a local DN. ● Local routing and traffic steering: The 5G core network selects the traffic to be routed to applications within a local DN, which may include the use of a single PDU session with multiple PDU session anchors (UL CL / IPv6 multi-homing) as described in section 5.6.4 of TS23.501. ● Session and service continuity enables the mobility of the UE and applications as described in section 5.6.9 of TS23.501. ● The application function may affect the selection and reselection of the UPF and traffic routing via the PCF or NEF, as described in more detail below.

[0005] The AF may send a request that affects the SMF routing decision of the traffic of a PDU session. The AF request may affect the selection or reselection of the UPF and enable the routing of user traffic for local access to the DN. The location of local access to the DN is identified by the DNAI. The AF may issue a request on behalf of an application that is not owned by the public land mobile network (PLMN) providing services to the UE. If the operator does not permit the AF to directly access the network, the AF uses the NEF to interact with the 5G core (5GC).

[0006] AF may be responsible for the selection or re - selection of applications within the local DN and / or relocation. Such functions are part of the application layer rather than part of the 5GC. Therefore, AF may request to be notified of events related to the PDU session, such as changes to the PDU session anchor. AF requests can be sent via the PCF (for a specific ongoing PDU session of an individual UE if AF can interact directly with the NF of the 5GC) or via the NEF. AF requests targeting existing or future PDU sessions of multiple UEs or any UE are sent via the NEF and can target multiple PCFs. The PCF converts the AF request into a policy applicable to the PDU session.

[0007] When AF subscribes to UP path management event notifications from the SMF (including notifications regarding how to reach the General Public Subscription Identifier (GPSI) via N6), such notifications are sent directly to AF by the SMF or via the NEF (without including the PCF). 3GPP (registered trademark) TS23.502 describes the related procedures and the roles of the related NFs in section 4.6.3.

[0008] AF requests may partially include the following information. ● Traffic description (mandatory): Defines the traffic affected, represented by a combination of the Data Network Name (DNN), optional single Network Slice Selection Assistance Information (S - NSSAI), and an application identifier or traffic filtering information. ● Potential locations of the application (conditional - may not exist if the request is for a subscription to notifications only): Indicates the potential locations of the application represented by a list of DNAIs. ● Information regarding the AF subscription to corresponding SMF events (optional): Indicates whether AF subscribes to the UP path of the PDU session and changes to the parameters of this subscription.

[0009] Note that only the items related to this disclosure are listed above. A more complete list is in Table 6.5.7-1 of TS23.501.

[0010] The scenarios related to this disclosure are related to providing session and service continuity to enable UE and application mobility. These methods may imply UP path management solutions for some existing PDU sessions in 5GC (e.g., modification of an existing PSA or addition of a new PSA). The detailed functions of the current 5GC Release 16 are described in Section 4.3.5 of TS23.502.

Summary of the Invention

Problems to be Solved by the Invention

[0011] During the above process, it may be possible to enable runtime adjustment between 5GC and AF. To support this function, the AF may include an indication of "AF confirmation expected" in its request. Based on this indication, when the SMF sends an early notification regarding the applied UP path change including the corresponding source and target DNAI, the SMF shall not proceed until it receives an affirmative response from the AF. This enables the AF to perform all the actions necessary to maintain service continuity on the new path. Similarly, the SMF may send a delayed notification to the AF to notify about the DNAI change. This notification may be used by the AF, for example, to trigger the source local DN mechanism to redirect an ongoing traffic session to the target local DN application. The SMF may refrain from activating the UP path to the new DNAI until it receives an affirmative AF response.

Means for Solving the Problems

[0012] A method and apparatus for adjusting seamless service continuity during Edge Application Server (EAS) relocation in a cellular communication system are disclosed. Embodiments of a method for adjusting seamless service continuity during EAS relocation in a cellular communication system are disclosed herein. In some embodiments, the method includes the Application Function (AF) sending a steering request including application steering information including a keepExistingPSA indication to the Policy Control Function (PCF), where the keepExistingPSA indication indicates that the current Data Network Access Identifier (DNAI) and the current User Plane (UP) path to the EAS should be maintained while the new DNAI and the new path to the EAS are being established. The method further includes, at the PCF, receiving the steering request from the AF and generating a Policy and Charging Control (PCC) rule based on the steering request, the PCC rule including application steering information including the keepExistingPSA indication. The method also includes providing the PCC rule to the Session Management Function (SMF). The method further includes, at the SMF, receiving the PCC rule from the PCF. The method further includes determining that a change of the PDU session anchor (PSA) of the Protocol Data Unit (PDU) session from a source PSA to a target PSA is to be performed. The method includes determining that a simultaneous connection via the source PSA and the target PSA is provided based on the keepExistingPSA indication. The method includes configuring the target PSA while maintaining the current DNAI and the UP connectivity to the EAS via the source PSA.

[0013] Embodiments of a method for adjusting seamless service continuity during relocation of an EAS in a cellular communication system are disclosed herein. In some embodiments, the method includes the AF sending a steering request including application steering information including a keepExistingPSA indication to the PCF, the keepExistingPSA indication indicating that the current DNAI and the current UP path to the EAS should be maintained while the new DNAI and the new path to the new EAS are being established. In some embodiments, the application steering information further includes a KeepExistingPSATimer indication indicating the period for maintaining the previous PDU session anchor (PSA). In some embodiments, the application steering information further includes an indication of a minimum time interval for considering the source branch point (BP) / uplink classifier (UL CL) as inactive.

[0014] In some embodiments, the application steering information further includes an indication of a minimum time interval for considering the source user plane function (UPF) as inactive. Some embodiments disclosed herein provide that the method further includes determining that an EAS change that requests a change in the DNAI is to be performed and invoking the Nnef_TrafficInfluence service including the application steering information. According to some embodiments disclosed herein, the method further includes determining that an EAS change that requires a change in the DNAI is to be performed and sending one of an Npcf_PolicyAuthorizationCreate service request including the application steering information and an Npcf_PolicyAuthorizationUpdate service request including the application steering information.

[0015] Embodiments of a network node implementing AF are disclosed herein, where AF enables seamless service continuity adjustment during EAS relocation in a cellular communication system. In some embodiments, the network node is configured to send a steering request including application steering information including a keepExistingPSA indication to the PCF, where the keepExistingPSA indication indicates that the current DNAI and the current UP path to the EAS should be maintained while a new path to a new DNAI and EAS is being established. Some embodiments disclosed herein may further provide a network node further configured to perform any of the steps of the methods disclosed above attributable to the network node.

[0016] Embodiments of a network node implementing AF are also disclosed herein, where AF enables seamless service continuity adjustment during EAS relocation in a cellular communication system. In some embodiments, the network node comprises a network interface and processing circuitry associated with the network interface. The processing circuitry is configured to send a steering request including application steering information including a keepExistingPSA indication indicating that the current DNAI and the current UP path to the EAS should be maintained while a new path to a new DNAI and EAS is being established to the PCF. Some embodiments disclosed herein may further provide a network node further configured to perform any of the steps of the methods disclosed above attributable to the network node.

[0017] To adjust seamless service continuity during EAS relocation, embodiments of a method executed at a PCF within the core network of a cellular communication system are also disclosed herein. In some embodiments, the method includes receiving a steering request from an AF that includes application steering information including a keepExistingPSA indication indicating that the current UP path to the current DNAI and EAS should be maintained while a new path to the new DNAI and EAS is being established. The method includes generating a PCC rule based on the steering request, the PCC rule including the application steering information. The method also includes providing the PCC rule to an SMF. Some embodiments disclosed herein provide that the steering request targets a new PDU session and that generating the PCC rule includes generating the PCC rule during establishment of the new PDU session. Some embodiments disclosed herein provide that the steering request targets an ongoing PDU session and that generating the PCC rule includes generating the PCC rule during modification of the ongoing PDU session.

[0018] Embodiments of network nodes implementing a PCF within the core network of a cellular communication system are also disclosed herein, where the PCF enables adjustment of seamless service continuity during EAS relocation. In some embodiments, the network node is configured to receive from the AF a steering request that includes application steering information including a keepExistingPSA indication, where the keepExistingPSA indication indicates that the current DNAI and the current UP path to the EAS should be maintained while a new path to a new DNAI and EAS is being established. The network node is configured to generate a PCC rule based on the steering request, where the PCC rule includes the application steering information. The network node is also configured to provide the PCC rule to the SMF. Some embodiments disclosed herein may further provide a network node that is further configured to perform any of the steps of the methods disclosed above attributable to the network node.

[0019] Embodiments of a network node implementing a PCF within a core network of a cellular communication system are also disclosed herein, where the PCF enables seamless service continuity adjustment during EAS relocation. In some embodiments, the network node comprises a network interface and a processing circuit associated with the network interface. The processing circuit is configured to receive a steering request from an AF, the steering request including application steering information including a keepExistingPSA indication indicating that the current UP path to the current DNAI and EAS should be maintained while a new path to a new DNAI and EAS is established. The processing circuit further comprises generating a PCC rule based on the steering request, the PCC rule including the application steering information. The processing circuit is also configured to provide the PCC rule to an SMF. Some embodiments disclosed herein may further provide a network node further configured to perform any of the steps of the methods disclosed above attributable to the network node.

[0020] To adjust seamless service continuity during EAS relocation, embodiments of a method executed at a SMF in a core network of a cellular communication system are also disclosed herein. In some embodiments, the method includes receiving a PCC rule including application steering information from a PCF, the keepExistingPSA indication indicating that the current UP path to the current DNAI and EAS should be maintained while the new path to the new DNAI and EAS is being established. The method further includes determining that a change of the PSA of a PDU session from a source PSA to a target PSA is to be performed. The method includes determining that simultaneous connectivity via the source PSA and the target PSA is to be provided based on the keepExistingPSA indication. The method includes configuring the target PSA while maintaining the UP connectivity to the current DNAI and EAS via the source PSA. Some embodiments disclosed herein further include that the application steering information further includes a KeepExistingPSATimer indication indicating a period for maintaining the previous PSA, and the method includes starting a timer at a time interval based on the indication of the period for maintaining the previous PSA, and maintaining the source BP / UL CL and the source UPF until the expiration of the timer. In some embodiments disclosed herein, the application steering information further includes an indication of a minimum time interval for considering the source BP / UL CL and the source UPF as inactive, and the method includes starting an inactive timer for traffic via the source BP / UL CL and the source UPF, the inactive timer having a value greater than or equal to the minimum time interval, and removing the source BP / UL CL and the source UPF after an inactive period specified by the inactive timer.

[0021] Embodiments of a network node implementing a SMF within the core network of a cellular communication system are also disclosed herein, and the SMF enables seamless service continuity to be coordinated during an EAS relocation. In some embodiments, the network node receives from the PCF a PCC rule including application steering information including a keepExistingPSA indication indicating that the current UP path to the current DNAI and EAS should be maintained while a new path to the new DNAI and EAS is being established. The network node is configured to determine that a change of the PSA of the PDU session from a source PSA to a target PSA is to be performed. The network node is configured to determine, based on the keepExistingPSA indication, that simultaneous connectivity via the source PSA and the target PSA is to be provided. The network node is configured to configure the target PSA while maintaining the UP connectivity to the current DNAI and EAS via the source PSA. Some embodiments disclosed herein may further provide a network node further configured to perform any of the steps of the methods disclosed above resulting from the network node.

[0022] Embodiments of a network node implementing a SMF within the core network of a cellular communication system are also disclosed herein, and the SMF enables seamless service continuity to be adjusted during EAS relocation. In some embodiments, the network node comprises a network interface and a processing circuit associated with the network interface. The processing circuit is configured to receive a PCC rule from a PCF, and the PCC rule includes application steering information including a keepExistingPSA indication indicating that the current DNAI and the current UP path to the EAS should be maintained while a new path to the new DNAI and the EAS is established. The processing circuit is further configured to determine that a change from a source PSA to a target PSA of a PDU session is to be performed. The processing circuit is configured to determine that a simultaneous connection via the source PSA and the target PSA is to be provided based on the keepExistingPSA indication. The processing circuit is configured to configure the target PSA while maintaining the UP connectivity to the current DNAI and the EAS via the source PSA. Some embodiments disclosed herein further provide that the processing circuit is further configured to perform any of the steps of the methods disclosed above attributable to the network node.

[0023] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects of the present disclosure and together with the description serve to explain the principles of the present disclosure.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5A

Figure 5B

Figure 6

Figure 7

Figure 8

DETAILED DESCRIPTION OF THE INVENTION

[0025] The following embodiments show information for enabling those skilled in the art to implement the embodiments and illustrate the best mode of implementing the embodiments. Reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure and recognize the application of these concepts that are not specifically mentioned herein. It should be understood that these concepts and applications are within the scope of the present disclosure.

[0026] Currently, there are specific challenges in existing approaches. Section 4.3.5.7 of TS23.502 describes the procedure for "Branch points or UL CL for PDU sessions and simultaneous change of additional PSA". In the description of this procedure, step 10 is as shown in Table 1 below.

[0027]

Table 1

[0028] However, the standard does not show anything regarding how the SMF knows whether session continuity is used during UL CL relocation. There may be an internal policy setting in the 5GC to determine this, but there is no possibility of dynamically controlling from the AF side whether session continuity is used (e.g., for a specific application or application session). Therefore, it is desirable that the AF can control whether session continuity should be used for a specific PDU session during UL CL relocation.

[0029] Also, as described in Note 7 of the reference text, the AF can send an explicit notification to the SMF to release the source UL CL and source local PSA, but the AF cannot indicate in advance the time period during which the old and new UP paths coexist.

[0030] Thus, certain aspects of the present disclosure and their embodiments may provide solutions to the above-described or other challenges. There are various embodiments that solve one or more of the challenges disclosed herein and are proposed herein. A system and method for adjusting seamless service continuity to the EAS during relocation are proposed, providing solutions to the foregoing or other challenges.

[0031] In some embodiments, the preferences related to edge relocation are sent along with the AF's impact on traffic routing and communicated by the AF. This information includes whether session continuity needs to be used during UL CL relocation and an indication of that period when simultaneous changes to UL CL and PSA are applied.

[0032] Certain embodiments may provide one or more of the following technical advantages. In particular, this solution enables the 5GC to make smarter decisions that better adapt to actual application needs by further enhancing AF control regarding traffic routing in a way that enables service continuity for EC services.

[0033] Before describing in more detail the method and apparatus for re - anchoring by SMF reselection, an exemplary cellular communication system in which some embodiments of the present disclosure may be implemented will first be described. In this regard, the following terms are defined.

[0034] Wireless node: As used herein, "wireless node" is either a wireless access node or a wireless communication device.

[0035] Wireless access node: As used herein, a "wireless access node" or "wireless network node" or "wireless access network node" is any node within a radio access network (RAN) of a cellular communication network that is operative to transmit and / or receive signals wirelessly. Some examples of wireless access nodes include base stations (e.g., a new radio (NR) base station (gNB) in a 5th generation (5G) NR network of the 3rd Generation Partnership Project (3GPP (R)), or an evolved Node B (eNB) which is an extension or evolution of a 3GPP Long Term Evolution (LTE) network), high-power or macro base stations, low-power base stations (e.g., micro base stations, pico base stations, home eNBs, etc.), relay nodes, network nodes implementing a part of the base station functionality (e.g., a network node implementing a gNB central unit (gNB-CU), or a network node implementing a gNB distributed unit (gNB-DU)), or network nodes implementing a part of the functionality of other types of wireless access nodes, but are not limited thereto.

[0036] Core network node: As used herein, a "core network node" is any type of node within the core network, or any node implementing core network functionality. Some examples of core network nodes include, for example, a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), etc. Some other examples of core network nodes include nodes 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), a Repository Function (NRF), a Policy Control Function (PCF), an Unified Data Management (UDM), etc.

[0037] Communication device: As used herein, a "communication device" is any type of device having access to an access network. Some examples of communication devices include, but are not limited to, mobile phones, smartphones, sensor devices, meters, vehicles, household appliances, medical devices, media players, cameras, or any type of household appliance such as a TV, radio, lighting equipment, tablet computer, laptop, or personal computer (PC). A communication device can be portable, handheld, included in a computer, or an in-vehicle mobile device that can communicate voice and / or data via a wireless or wired connection.

[0038] Wireless communication device: One type of communication device is a wireless communication device that can be any type of wireless device having access to a wireless network (e.g., a cellular network), i.e., being served by a wireless network. Some examples of wireless communication devices include, but are not limited to, user equipment (UE) within a 3GPP (registered trademark) network, machine type communication (MTC) devices, and Internet of Things (IoT) devices. Such wireless communication devices can be, or can be implemented in, mobile phones, smartphones, sensor devices, meters, vehicles, household appliances, medical devices, media players, cameras, or any type of household appliance such as a TV, radio, lighting equipment, tablet computer, laptop, personal computer (PC), etc., but not limited thereto. A wireless communication device can be portable, handheld, included in a computer, or an in-vehicle mobile device that can communicate voice and / or data via a wireless connection.

[0039] Network node: As used herein, a "network node" is any node that is part of the RAN or core network of a cellular communication network / system.

[0040] The description in this specification focuses on 3GPP (registered trademark) cellular communication systems, and it should be noted that 3GPP (registered trademark) terms or terms similar to 3GPP (registered trademark) terms are often used. However, the concepts disclosed in this specification are not limited to 3GPP (registered trademark) systems.

[0041] In the description of this specification, the term "cell" may be referred to. However, with respect to the concept of 5G NR in particular, since beams can be used instead of cells, it is important to note that the concepts described in this specification are equally applicable to both cells and beams.

[0042] FIG. 1 shows an example of a cellular communication system 100 in which embodiments of the present disclosure can be implemented. In the embodiments described herein, the cellular communication system 100 is a 5G system (5GS) including a next-generation RAN (NG-RAN) and a 5G core (5GC), or an evolved packet system (EPS) including an evolved universal terrestrial RAN (E-UTRAN) and an evolved packet core (EPC). In this example, the RAN includes base stations 102-1 and 102-2, which are NR base stations (gNBs) in the 5GS and optionally next-generation eNBs (ng-eNBs) (e.g., LTE RAN nodes connected to the 5GC), and control corresponding (macro) cells 104-1 and 104-2. The base stations 102-1 and 102-2 are referred to herein collectively as base station 102 and also individually as base station 102. Similarly, the (macro) cells 104-1 and 104-2 are referred to herein collectively as (macro) cell 104 and also individually as (macro) cell. The RAN may also include several low-power nodes 106-1 to 106-4 that control corresponding small cells 108-1 to 108-4. The low-power nodes 106-1 to 106-4 can be small base stations (such as pico or femto base stations) or remote radio heads (RRHs), etc. In particular, although not shown, one or more of the small cells 108-1 to 108-4 can be provided by the base station 102 instead. The low-power nodes 106-1 to 106-4 are referred to herein collectively as low-power node 106 and also individually as low-power node 106. Similarly, the small cells 108-1 to 108-4 are referred to herein collectively as small cell 108 and also individually as small cell 108. The cellular communication system 100 also includes a core network 110 called 5GC in the 5G system (5GS). The base stations 102 (and optionally the low-power nodes 106) are connected to the core network 110.

[0043] Base station 102 and low power node 106 provide services to wireless communication devices 112-1 to 112-5 within corresponding cells 104 and 108. The wireless communication devices 112-1 to 112-5 are referred to herein collectively as wireless communication device 112 and individually as wireless communication device 112. In the following description, the wireless communication device 112 is often a UE, but the present disclosure is not limited thereto.

[0044] FIG. 2 shows a wireless communication system represented as a 5G network architecture composed of core network functions (NFs), where the interaction between any two NFs is represented by point-to-point reference points / interfaces. FIG. 2 can be seen as one particular implementation of the system 100 of FIG. 1.

[0045] Looking from the access side, the 5G network architecture shown in FIG. 2 has a plurality of UEs 112 connected to either RAN 102 or an access network (AN), and an AMF 200. Typically, RAN 102 includes a base station such as an eNB or a gNB, for example. Looking from the core network side, the 5GC core NFs shown in FIG. 2 include an NSSF 202, an AUSF 204, a UDM 206, an AMF 200, an SMF 208, a PCF 210, and an application function (AF) 212.

[0046] The reference point representation of the 5G network architecture is used to develop detailed call flows with canonical standardization. The N1 reference point is defined to carry signaling between the UE 112 and the AMF 200. The reference points for connecting between the RAN 102 and the AMF 200, and between the RAN 102 and the UPF 214 are defined as N2 and N3 respectively. There is a reference point N11 between the AMF 200 and the SMF 208, which means that the SMF 208 is at least partially controlled by the AMF 200. N4 is used by the SMF 208 and the UPF 214, as a result, the UPF 214 is configured using control signals generated by the SMF 208, and the UPF 214 can report its status to the SMF 208. N9 is the reference point for the connection between different UPF 214s, and N14 is the reference point for the connection between different AMF 200s. N15 and N7 are defined for the PCF 210 to apply policies to the AMF 200 and the SMF 208 respectively. N12 is required for the AMF 200 to perform authentication of the UE 112. N8 and N10 are defined because the subscriber data of the UE 112 is required by the AMF 200 and the SMF 208.

[0047] The 5GC network intends to separate the user plane (UP) and the control plane (CP). While the CP carries signaling within the network, the UP carries user traffic. In Figure 2, the UPF 214 is in the UP, and all other NFs, namely the AMF 200, SMF 208, PCF 210, AF 212, NSSF 202, AUSF 204 and UDM 206 are in the CP. By separating the UP and the CP, it is guaranteed that the resources of each plane are scaled individually. Also, the UPF can be distributed separately from the CP functions. In this architecture, for some applications that require low latency, the UPF can be placed very close to the UE to shorten the round-trip time (RTT) between the UE and the data network.

[0048] The core 5G network architecture is composed of modularized functions. For example, the AMF 200 and the SMF 208 are independent functions within the CP. The separated AMF 200 and SMF 208 enable independent evolution and scaling. As shown in Figure 2, other CP functions such as the PCF 210 and the AUSF 204 can be separated. The modularized function design allows the 5GC network to flexibly support various services.

[0049] Each NF interacts directly with another NF. An intermediate function can be used to route messages from one NF to another NF. In the CP, a series of interactions between two NFs are defined as services, so they can be reused. This service enables modularity support. The UP supports interactions such as transfer operations between different UPFs.

[0050] Figure 3 shows a 5G network architecture that uses service-based interfaces between NFs within the CP instead of the point-to-point reference points / interfaces used in the 5G network architecture of Figure 2. However, the NFs described above with reference to Figure 2 correspond to the NFs shown in Figure 3. Services provided by an NF to other authenticated NFs, etc., can be exposed to the authenticated NFs via the service-based interfaces. In Figure 3, the service-based interfaces are indicated by the letter "N" followed by the name of the NF. For example, in the case of the service-based interface of the AMF 200, it is Namf, and in the case of the service-based interface of the SMF 208, it is Nsmf. The NEF 300 and the NRF 302 in Figure 3 are not shown in Figure 2 above. However, even if not explicitly shown in Figure 2, it should be clearly stated that all NFs shown in Figure 2 can interact with the NEF 300 and the NRF 302 in Figure 3 as needed.

[0051] Some of the characteristics of the NFs shown in FIGS. 2 and 3 can be explained as follows. The AMF 200 provides UE-based authentication, authorization, mobility management, etc. Since the AMF 200 is independent of access technologies, even a UE 112 using multiple access technologies is basically connected to a single AMF 200. The SMF 208 is responsible for session management and assigns an Internet Protocol (IP) address to the UE. Also, the SMF 208 selects and controls the UPF 214 for data transfer. When the UE 112 has multiple sessions, different SMFs 208 can be assigned to each session, managed individually, and different functions can be provided for each session. The AF 212 provides information regarding a packet flow to the PCF 210 responsible for policy control in order to support QoS. Based on this information, the PCF 210 determines policies regarding mobility and session management for operating the AMF 200 and the SMF 208 appropriately. The AUSF 204 supports functions such as UE authentication, etc., and stores data for UE authentication, etc., and the UDM 206 stores subscription data of the UE 112. A data network (DN) that is not part of the 5GC network provides Internet access or operator services, etc. The NFs can be implemented as network elements on dedicated hardware, as software instances executed on dedicated hardware, or as virtualized functions instantiated on a suitable platform, such as a cloud infrastructure, etc.

[0052] As described above, a system and method for adjusting seamless service continuity to the EAS during relocation are disclosed herein. This solution is related to the impact of the AF on traffic routing and affects the following two service operations. · If the AF request targets individual UE addresses that need to be received by the relevant PCF, the indication should be sent in the Npcf_PolicyAuthorizationCreate / Update service request. The AF either directly sends the AF request to the PCF and then directly invokes Npcf_PolicyAuthorization, or the NEF invokes Npcf_PolicyAuthorization (see section 4.3.6.4 of TS23.502). · If the AF request is not identified by the UE's Internet Protocol (IP) address, the indication is sent to the NEF in an Nnef_TrafficInfluence_Create or Update request (see section 4.3.6.2 of TS23.502), which is stored in the UDR and the PCF receives it as needed.

[0053] There are the following two triggers for application relocation that may imply the transmission of the above messages. · A change in the application server is triggered by the 5GC attempting to change the UE's local PSA. This may occur, for example, due to the UE's mobility. This change in the UP path can be notified to the application server side via the AF by the user plane management notification of PSA relocation / DNAI change. · A change in the application server is initiated from the application side (e.g., for load redispersion due to congestion of the edge application server providing the service). In this case, the role of the 5GC is to ensure connectivity to the new EAS by setting the appropriate UL CL / BP and the local PSA.

[0054] Examples of the procedures for both scenarios are shown in order below.

[0055] Figures 4A and 4B show the operations for EAS relocation triggered by 5GC. The following procedures assume that the runtime adjustment between 5GC and the application (AF) is enabled. The adjustment provides notification and control of the new and old ULCL / BP and the local PSA. The explanations for each step of the procedures shown in Figures 4A and 4B are provided below.

[0056] In step 401 of Figure 4A, before or during the edge application connection, the AF may send a request that affects the traffic routing of the session or the individual UE address (see Sections 4.3.6.2 and 4.6.3.4 of TS23.502). The request provides traffic filters, DNAI, and N6 traffic routing information. The application steering information may be provided by other means (e.g., as part of a service level agreement (SLA) and, if necessary. See, for example, Solution #3 of TR23.748). Further, the subscription to the DNAI change notification includes the application's domain name and an indication that "AF confirmation is expected" and is sent to the core network. This procedure is similar to steps 1 to 4 defined in Section 4.3.6.2 of TS23.502.

[0057] Furthermore, the AF may also include a new keepExistingPSA indication in the steering request, which indicates that in the case of a change in the UP path to the specified DNAI, the existing UP path needs to be temporarily maintained for the UE both during and after the setup of the new UP path (i.e., session continuity is used during UL CL relocation). The AF in some embodiments may also provide an input regarding the period for maintaining the previous PSA. According to some embodiments, the AF may use the KeepExistingPSATimer indication to indicate the minimum time interval for considering the previous path as inactive.

[0058] In step 402, the PCF generates a PCC rule based on the AF request and provides the PCC rule to the SMF. The PCC rule includes a keepExistingPSA indication and additional information. This step can occur during the establishment or modification of a PDU session depending on whether the request is for an ongoing PDU session. It is assumed that the edge application connection is set up using one of the mechanisms proposed for the detection and selection of the EAS (such as solution #3 in TR23.748). Originally, traffic flows towards the old EAS via the source BP / UL CL and the source UPF (PSA2) set up based on the PCC rule of this application.

[0059] In step 403, the SMF determines that relocation of the source BP / UL CL and the source UPF (PSA2) is required. The relocation can be triggered by UE mobility.

[0060] In step 404, based on the AF subscription, the SMF sends an early notification including the corresponding source and target DNAI to the AF. The SMF does not proceed with the processing until it receives an affirmative response from the AF as described in section 5.6.7 of TS23.501.

[0061] In step 405, based on the target DNAI of the notification received in step 404, the AF (or some other control logic triggered by the AF) determines that relocation of the application server is required and determines a new edge AS.

[0062] In step 406, AF sends the Nsmf_EventExposure_AppRelocationInfo service operation for this UE to the SMF as described in section 4.3.6.3 of TS 23.502. Note that at this point, the old EAS is still handling the edge application connection (although the instantiation and context migration of the new EAS may have been started). In this message, AF may confirm the notification and provide the N6 traffic routing information associated with the target DNAI.

[0063] In step 407, the SMF determines that for this session, it is necessary to perform a simultaneous change of the PDU session's BP or UL CL and the additional PSA (as described in section 4.3.5.7 of TS 23.502). The SMF infers from the keepExistingPSA indication in the PCC rule that session continuity is used during UL CL relocation, sets up the target BP / UL CL determined in step 403 and the target UPF (PSA2), and configures the filter based on the steering information already available (see step 401). To support session continuity during UL CL relocation and EAS migration, a temporary N9 transfer tunnel is established between the source UL CL and the target UL CL. This is described in section 5.6.4.2 of TS 23.501. The current source BP / UL CL and source UPF (PSA2) are maintained for a while, and a timer is started with a value considering the information received from the AF.

[0064] In some embodiments, the SMF can set an inactive timer for traffic via the source BP / UL CL and the source UPF (PSA2) and remove them after the inactive period. The inactive timer, if any, has a value greater than any minimum time interval considered for the previous path provided by the AF to be inactive (i.e., during the configurable period, all active traffic flowing through the AF ceases to exist). According to some embodiments, the AF can send an explicit notification that the previous connection is no longer required.

[0065] In step 408, after the target BP / UL CL and the target UPF (PSA3) are provisioned (see steps 2 - 8 of Figure 4.3.5.7 - 1 in TS23.502), the SMF sends an event exposure (i.e., rate notification) for the new UP path to the AF. If it is sent to the NEF, as specified in section 4.3.6.3 of TS23.502, the NEF converts it to Nnef_TraffcInfluence_Notify to the AF. It is noted that UE traffic can reach the old EAS via the source BP / ULCL and the source UPF (PSA2). This is particularly useful while the EAS relocation is in progress and allows for a switch to the new EAS when it is more application - suitable. Thereafter, the operation continues with Figure 4B.

[0066] Referring now to Figure 4B, in step 409, the context migration between the old EAS and the new EAS is completed. Note that this step can be executed at any time after step 405 and can be executed before steps 406 - 408.

[0067] In step 410, after both steps 408 and 409 are completed, the application client is instructed on when and how to switch to the new EAS using application layer procedures. There may be an instruction sent to the application client on how to proceed (e.g., continue to use the old EAS, send traffic to both, or other application-specific procedures). All traffic to the new EAS goes through the target BP / UL CL and target UPF (PSA3) as provisioned in step 407. UE application traffic is started towards the new EAS on the path via the target BP / UL CL and target UPF (PSA3).

[0068] In step 411, the SMF removes the source BP / UL CL and source UPF (PSA2) after the timer started in step 407 expires.

[0069] Figures 5A and 5B show the operations executed when edge relocation is triggered by an application. The AF is assumed to be able to obtain information on whether EAS relocation is necessary based on, for example, a notification from the edge application itself, a notification from the application layer management system, or a notification from other systems. The AF also receives information regarding the target DNAI, the UE IP address of the ongoing PDU session affected by the EAS relocation, and the IP address related to the target EAS.

[0070] If the change of EAS does not involve a change of DNAI, it can be fully processed by the application layer (e.g., following steps 409, 410, and 411 as described above with respect to Figures 4A and 4B). If the change of EAS includes a change of DNAI, it needs to be processed in cooperation with the 5GC as described in the following steps.

[0071] In Figure 5A, steps 501 and 502 are the same as those described above with respect to Figures 4A and 4B, resulting in an application connection to the legacy EAS via source BP / UL CL and source UPF (PSA2).

[0072] In step 503, AF may determine that an EAS change that requires a change in DNAI is necessary.

[0073] In step 504, if the impact occurs via the NEF, AF individually invokes the Nnef_TrafficInfluence service for each individual UE IP address or, as described in section 4.3.6.4 of TS23.502, uses the BSF to find the PCF of the individual UE and sends an Npcf_PolicyAuthorizationCreate / Update service request. If not already executed in step 501, AF also includes the new keepExistingPSA indication and time information in the message.

[0074] In some embodiments, since a server relocation event triggered by an application may generally involve multiple UEs, optimization steps can be used to reduce the need for signaling in step 506. In step 506, AF invokes the Nnef_TrafficInfluence service as described in section 4.3.6.2 of TS23.502, where the DNAI specifies the identifier of the target UE and the traffic descriptor further narrows down the scope of the target traffic affected (represented by a combination of DNN, optional S-NSSAI, application identifier, or traffic filtering information).

[0075] In step 505, the PCF triggers a PCC update to the SMF to use the target DNAI (as in step 503) for a given PDU session.

[0076] In step 506, the PCC change triggers the SMF to determine whether a change to the PSA is possible and / or convenient, and if so, the SMF determines the target UL CL / BP and the UPF.

[0077] In step 507, early notification of the SMF to the AF can trigger an EAS relocation.

[0078] Steps 508 - 513 are the same as steps 406 - 411 described above with respect to FIGS. 4A and 4B.

[0079] FIG. 6 is a block diagram of a network node 600 according to some embodiments of the present disclosure. Optional features are shown in dashed lines. The network node 600 can be, for example, a network node that implements all or part of the functions of an NF (e.g., SMF or PCF) or AF according to any of the embodiments described herein. As shown, the network node 600 includes one or more processors 604 (e.g., a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc.), a memory 606, and a network interface 608. The one or more processors 604 are also referred to herein as a processing circuit. The one or more processors 604 operate to provide one or more functions of an NF (e.g., SMF or AMF) or AF as described herein. In some embodiments, the functions are implemented, for example, by software stored in the memory 606 and executed by the one or more processors 604.

[0080] FIG. 7 is a block diagram showing a virtualized implementation of network node 600 according to some embodiments of the present disclosure. As used herein, a "virtualized" network node is an implementation of network node 600 in which at least a portion of the functionality of network node 600 is realized as virtual components (e.g., via virtual machines running on physical processing nodes within the network). As illustrated, in this example, network node 600 includes one or more processing nodes 700 coupled to network 702 or included as part of network 602. Each processing node 700 includes one or more processors 704 (e.g., CPUs, ASICs, FPGAs, etc.), memory 706, and a network interface 708.

[0081] In this example, the functionality 710 of network node 600 described herein (e.g., one or more functions of an NF (e.g., the described SMF or AMF) or AF) is implemented on one or more processing nodes 700 or distributed among two or more processing nodes 700 in any desired manner. In some particular embodiments, some or all of the functionality 710 of network node 600 described herein is implemented as virtual components executed by one or more virtual machines implemented in a virtual environment hosted by processing node 700.

[0082] In some embodiments, there is provided a computer program including instructions that, when executed by at least one processor, cause the at least one processor to perform the functionality of network node 600 or a node (e.g., processing node 700) that performs one or more of the functionality 710 of network node 600 in a virtual environment according to any of the embodiments described herein. In some embodiments, there is provided a carrier including the aforementioned computer program product. The carrier is one of an electronic signal, an optical signal, a wireless signal, or a computer-readable storage medium (e.g., a non-transitory computer-readable medium such as a memory).

[0083] FIG. 8 is a block diagram of a network node 600 according to some other embodiments of the present disclosure. The network node 600 includes one or more modules 800, each of which is implemented in software. The modules 800 operate to provide the functions of the network node 600 described (e.g., one or more functions of the described NF (such as SMF or AMF) or AF). This discussion is equally applicable to the processing nodes 700 of FIG. 7, where the modules 800 may be implemented in one of the processing nodes 700 or distributed across two or more processing nodes 700.

[0084] Any suitable steps, methods, features, functions, or advantages disclosed herein may be performed through one or more functional units or modules of one or more virtual devices. Each virtual device may comprise several of these functional units. These functional units may include processing circuitry that may include one or more microprocessors or microcontrollers, and other digital hardware that may include a digital signal processor (DSP), dedicated digital logic, etc. The processing circuitry is configured to execute program code stored in a memory, which may include one or more types of memory such as read-only memory (ROM), random access memory (RAM), cache memory, flash memory devices, optical storage devices, etc. The program code stored in the memory includes program instructions for executing one or more communication and / or data communication protocols, and in some embodiments, program instructions for performing one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause each functional unit to perform corresponding functions according to one or more embodiments of the present disclosure.

[0085] The processes in the figures may indicate a particular order of operations performed according to particular embodiments of the present disclosure, but it should be understood that such order is exemplary (e.g., alternative embodiments may perform operations in a different order, combine particular operations, and repeat particular ones).

[0086] Although not limited thereto, some exemplary embodiments of the present disclosure are provided below.

[0087] Embodiment 1: A method executed in a core network of a cellular communication system to adjust seamless service continuity during edge application server (EAS) relocation, comprising: ● In an application function (AF), 〇 Sending a steering request to a policy control function (PCF), the steering request including application steering information including a keepExistingPSA indication, the keepExistingPSA indication indicating that the current data network access identifier (DNAI) and the current user plane (UP) path to the edge application server (EAS) should be maintained while a new DNAI and a new path to the EAS are being established; ● In the PCF, 〇 Receiving the steering request from the AF, 〇 Generating a policy and charging control (PCC) rule including the application steering information based on the steering request, 〇 Providing the PCC rule to a session management function (SMF); ● In the SMF, 〇 Receiving the PCC rule from the PCF, 〇 Determining that a simultaneous change of a branch point (BP) or UL CL for a protocol data unit (PDU) session and an additional PDU session anchor (PSA) is to be performed, 〇 Determining that session continuity during UL CL relocation is to be used based on the keepExistingPSA indication, 〇 Configuring a target BP or UL CL and a target user plane function (UPF); A method including the above.

[0088] Embodiment 2: A method executed by an application function (AF) of a core network of a cellular communication system to adjust seamless service continuity during edge application server (EAS) relocation, the method including transmitting a steering request to a policy control function (PCF), the steering request including application steering information including a keepExistingPSA indication, the keepExistingPSA indication indicating that a current data network access identifier (DNAI) and a current user plane (UP) path to an edge application server (EAS) should be maintained while a new DNAI and a new path to the EAS are being established.

[0089] Embodiment 3: The method according to Embodiment 2, wherein the application steering information further includes an indication indicating a period for maintaining a previous protocol data unit (PDU) session anchor (PSA).

[0090] Embodiment 4: The method according to Embodiment 2, wherein the application steering information further includes an indication of a minimum time interval for considering a source branch point (BP) / uplink classifier (UL CL) and a source user plane function (UPF) as inactive.

[0091] Embodiment 5: The method according to Embodiment 2, further including: ● determining that an EAS change requesting a change in DNAI is to be executed; ● invoking an Nnef_TrafficInfluence service including application steering information, wherein the DNAI designates an identifier of one or more target user devices (UEs).

[0092] Embodiment 6: The method according to Embodiment 2, further including: ● determining that an EAS change requesting a change in DNAI is to be executed; A method comprising: sending an Npcf_PolicyAuthorizationCreate service request or an Npcf_PolicyAuthorizationUpdate service request including application steering information.

[0093] Embodiment 7: An application function (AF) of a core network of a cellular communication system, the AF enabling seamless service continuity adjustment during edge application server (EAS) relocation, the AF being configured to send a steering request to a policy control function (PCF), the steering request including application steering information including a keepExistingPSA indication, the keepExistingPSA indication indicating that the current data network access identifier (DNAI) and the current user plane (UP) path to the edge application server (EAS) should be maintained while a new DNAI and a new path to the EAS are being established.

[0094] Embodiment 8: The AF according to Embodiment 7, further configured to execute the method according to any one of Embodiments 2 to 6.

[0095] Embodiment 9: A network node that executes an application function (AF) of a core network of a cellular communication system, the AF enabling seamless service continuity adjustment during edge application server (EAS) relocation, the network node ● a network interface, and ● A network node comprising a processing circuit associated with a network interface, the processing circuit being configured to cause the network node to execute an AF, the AF being configured to send a steering request to a policy control function (PCF), the steering request including application steering information including a keepExistingPSA indication, the keepExistingPSA indication indicating that the current data network access identifier (DNAI) and the current user plane (UP) path to the edge application server (EAS) should be maintained while a new DNAI and a new path to the EAS are being established.

[0096] Embodiment 10: The network node according to Embodiment 9, wherein the AF is further configured to execute the method according to any one of Embodiments 2 to 6.

[0097] Embodiment 11: A method executed in a policy control function (PCF) within the core network of a cellular communication system to adjust seamless service continuity during edge application server (EAS) relocation, comprising: ● Receiving, from an application function (AF), a steering request including application steering information including a keepExistingPSA indication indicating that session continuity is maintained during uplink classifier (UL CL) relocation; ● Generating a policy and charging control (PCC) rule based on the steering request, the PCC rule including the application steering information; ● Providing the PCC rule to a session management function (SMF). A method comprising the above steps.

[0098] Embodiment 12: The method according to Embodiment 11, wherein ● The steering request targets a new PDU session. ●Generating PCC rules is a method that is executed during the establishment of a new PDU session.

[0099] Embodiment 13: The method according to Embodiment 11, wherein ●The steering request targets an ongoing PDU session, ●Generating PCC rules is a method that is executed during the modification of an ongoing PDU session.

[0100] Embodiment 14: A policy control function (PCF) of the core network of a cellular communication system, wherein the PCF enables seamless service continuity adjustment during edge application server (EAS) relocation, and the PCF ●Receives from an application function (AF) a steering request including application steering information containing a keepExistingPSA indication indicating that session continuity is maintained during uplink classifier (UL CL) relocation, ●Based on the steering request, generates a policy and charging control (PCC) rule, wherein the PCC rule includes application steering information, ●Provides the PCC rule to a session management function (SMF), and is configured to perform the above.

[0101] Embodiment 15: The PCF according to Embodiment 14, further configured to execute the method according to any one of Embodiments 12 to 13.

[0102] Embodiment 16: A network node that executes a policy control function (PCF) of the core network of a cellular communication system, wherein the PCF enables seamless service continuity adjustment during edge application server (EAS) relocation, and the network node ●A network interface, ● It includes a processing circuit associated with a network interface, and the processing circuit is configured to cause a network node to execute a PCF, and the PCF 〇 Receiving, from an application function (AF), a steering request including application steering information including a keepExistingPSA indication indicating that session continuity is maintained during uplink classifier (UL CL) relocation 〇 Generating a policy and charging control (PCC) rule based on the steering request, where the PCC rule includes application steering information 〇 Providing the PCC rule to a session management function (SMF) A network node configured to perform the above.

[0103] Embodiment 17: The network node according to Embodiment 16, wherein the AF is further configured to execute the method according to any one of Embodiments 12 to 13

[0104] Embodiment 18: A method executed in a session management function (SMF) in the core network of a cellular communication system to adjust seamless service continuity during edge application server (EAS) relocation, comprising: ● Receiving a policy and charging control (PCC) rule from a policy control function (PCF), where the PCC rule includes application steering information including a keepExistingPSA indication indicating that session continuity is maintained during uplink classifier (UL CL) relocation ● Determining that a simultaneous change between a branch point (BP) or (UL CL) for a protocol data unit (PDU) session and an additional PDU session anchor (PSA) is to be executed ● Determining that session continuity during UL CL relocation is to be used based on the keepExistingPSA indication ● Comprising a target BP or UL CL and a target user plane function (UPF). A method including this.

[0105] Embodiment 19: The method according to Embodiment 18, wherein ● The application steering information further includes an indication of the period for maintaining the previous PSA. ● The method further includes 〇 Starting a timer for a time interval based on the indication of the period for maintaining the previous PSA. 〇 Maintaining the source BP / UL CL and the source UPF until the expiration of the timer.

[0106] Embodiment 20: The method according to Embodiment 18, wherein ● The application steering information further includes an indication of the minimum time interval for considering the source BP / UP CL and the source UPFF as inactive. ● The method further includes 〇 Starting an inactive timer for traffic passing through the source BP / UL CL and the source UPF, where the inactive timer has a value greater than or equal to the minimum time interval. 〇 Removing the source BP / UL CL and the source UPF after the inactive period specified by the inactive timer.

[0107] Embodiment 21: A session management function (SMF) of the core network of a cellular communication system, where the SMF enables seamless service continuity adjustment during edge application server (EAS) relocation, and the SMF ● Receives policy and charging control (PCC) rules from a policy control function (PCF), where the PCC rules include application steering information including a keepExistingPSA indication indicating that session continuity is maintained during uplink classifier (UL CL) relocation. ● Determine that a simultaneous change of a branch point (BP) or (UL CL) for a protocol data unit (PDU) and an additional PDU session anchor (PSA) is to be performed; ● Determine that session continuity during UL CL relocation is used based on a keepExistingPSA indication; ● Configure a target BP or UL CL and a target user plane function (UPF); An SMF configured to perform the above.

[0108] Embodiment 22: The SMF according to Embodiment 21, further configured to execute the method according to any one of Embodiments 19 to 20.

[0109] Embodiment 23: A network node that executes a session management function (SMF) of a core network of a cellular communication system, the SMF enables seamless service continuity adjustment during edge application server (EAS) relocation, and the network node ● A network interface; ● A processing circuit associated with the network interface, the processing circuit is configured to cause the network node to execute the SMF, and the SMF 〇 Receive a steering request including application steering information including a keepExistingPSA indication indicating that session continuity is maintained during uplink classifier (UL CL) relocation from an application function (AF); 〇 Based on the steering request, generate a policy and charging control (PCC) rule, the PCC rule including the application steering information; 〇 Provide the PCC rule to a session management function (SMF); A network node configured to perform the above.

[0110] Embodiment 24: A network node according to Embodiment 23, wherein the AF is further configured to execute the method according to any one of Embodiments 19 to 20.

[0111] At least some of the following abbreviations may be used in the present disclosure. If there are contradictions between abbreviations, the usage method above shall be prioritized. If listed multiple times below, the first list shall be prioritized over subsequent lists. ● 3GPP Third Generation Partnership Project ● 5G Fifth Generation ● 5GC Fifth Generation Core ● 5GS Fifth Generation System ● AF Application Function ● AMF Access and Mobility Function ● AN Access Network ● AP Access Point ● ASIC Application Specific Integrated Circuit ● AUSF Authentication Server Function ● CPU Central Processing Unit ● DN Data Network ● DSP Digital Signal Processor ● eNB Enhanced or evolved Node B ● EPS Evolved Packet System ● E-UTRA Evolved Universal Terrestrial Radio Access ● FPGA Field Programmable Gate Array ● gNB New Radio Base Station ● gNB-DU New Radio Base Station Distributed Unit ● HSS Home Subscriber Server ● IoT Internet of Things ● IP Internet Protocol ● LTE Long Term Evolution ● MME Mobility Management Entity ● MTC Machine Type Communication ● NEF Network Exposure Function ● NF Network Disclosure Function ● NR New Radio ● NRF Network Function Repository Function ● NSSF Network Slice Selection Function ● OTT Over the Top ● PC Personal Computer ● PCF Policy Control Function ● P-GW Packet Data Network Gateway ● QoS Quality of Service ● RAM Random Access Memory ● RAN Radio Access Network ● ROM Read Only Memory ● RRH Remote Radio Head ● RTT Round Trip Time ● SCEF Service Capability Exposure Function ● SMF Session Management Function ● UDM Unified Data Management ● UE User Equipment ● UPF User Plane Function

[0112] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered to be within the scope of the concepts disclosed herein.

Claims

1. A method for simultaneous connection via a source protocol data unit session anchor (PSA) and a target PSA during relocation of an edge application server (EAS) in a cellular communication system, comprising: In an application function (AF), sending an AF request including application steering information to a policy control function (PCF), wherein the application steering information includes a keepExistingPSA indication indicating that the current data network access identifier (DNAI) and the current user plane (UP) path to the EAS should be maintained while a new DNAI and a new path to the new EAS are being established, and an indication indicating a period for maintaining the source PSA; In the PCF, receiving the AF request from the AF; generating a policy and charging control (PCC) rule based on the AF request, wherein the PCC rule includes the application steering information including the keepExistingPSA indication and the indication indicating a period for maintaining the source PSA; providing the PCC rule to a session management function (SMF); In the SMF, receiving the PCC rule from the PCF; determining that a change from the source PSA to the target PSA of a protocol data unit (PDU) session's PSA is to be executed; determining that a simultaneous connection via the source PSA and the target PSA is to be provided based on the keepExistingPSA indication; starting a timer for a time interval based on the indication of the period for maintaining the source PSA; maintaining a source branch point or a source uplink classifier and a source user plane function until the period of the timer elapses; configuring the target PSA while maintaining the current DNAI and the UP connection to the EAS via the source PSA; A method comprising the above steps.

2. A method for enabling simultaneous connection via a source protocol data unit session anchor (PSA) and a target PSA during relocation of an edge application server (EAS) in a cellular communication system, comprising: The application function (AF) includes sending an AF request including application steering information to a policy control function (PCF), wherein the application steering information includes a keepExistingPSA indication indicating that the current data network access identifier (DNAI) and the current user plane (UP) path to the EAS should be maintained while a new path to a new DNAI and a new EAS is being established, and an indication indicating the period for maintaining the source PSA, a method.

3. The method according to claim 2, wherein the application steering information further includes an indication of a minimum time interval for considering the source branch point (BP) / uplink classifier (UL CL) as inactive, a method.

4. The method according to claim 2, wherein the application steering information further includes an indication of a minimum time interval for considering the source user plane function (UPF) as inactive, a method.

5. The method according to claim 2, further comprising determining that an EAS change requesting a change in DNAI is to be executed, starting an Nnef_Traffic Influence service including the application steering information, a method including.

6. The method according to claim 2, further comprising determining that an EAS change requesting a change in DNAI is to be executed, sending one of an Npcf_PolicyAuthorizationCreate service request including the application steering information and an Npcf_PolicyAuthorizationUpdate service request including the application steering information, a method including.

7. A network node implementing an application function (AF), wherein the AF enables requesting a simultaneous connection via a source protocol data unit session anchor (PSA) and a target PSA during relocation of an edge application server (EAS) of a cellular communication system, the network node is configured to send an AF request including application steering information to a policy control function (PCF), The network node, wherein the application steering information includes a keepExistingPSA indication indicating that the current data network access identifier (DNAI) and the current user plane (UP) path to the EAS should be maintained while a new DNAI and a new path to a new EAS are being established, and an indication indicating the period for maintaining the source PSA.

8. The network node according to claim 7, wherein the network node is further configured to execute the method according to any one of claims 3 to 6.

9. A method executed in a policy control function (PCF) in a core network of a cellular communication system to enable simultaneous connection via a source protocol data unit session anchor (PSA) and a target PSA during relocation of an edge application server (EAS), comprising: receiving, from an application function (AF), an AF request including application steering information, the application steering information including a keepExistingPSA indication indicating that the current data network access identifier (DNAI) and the current user plane (UP) path to the EAS should be maintained while a new DNAI and a new path to a new EAS are being established, and an indication indicating the period for maintaining the source PSA; generating, based on the AF request, a policy and charging control (PCC) rule, the PCC rule including the application steering information; providing the PCC rule to a session management function (SMF). A method comprising the above steps.

10. The method according to claim 9, wherein the AF request targets a new protocol data unit (PDU) session, and generating the PCC rule includes generating the PCC rule during establishment of the new PDU session.

11. The method according to claim 9, wherein the AF request targets an ongoing protocol data unit (PDU) session, and generating the PCC rule includes generating the PCC rule during modification of the ongoing PDU session.

12. A network node that implements a policy control function (PCF) of a core network of a cellular communication system, wherein the PCF enables simultaneous connection via a source protocol data unit session anchor (PSA) and a target PSA during relocation of an edge application server (EAS), the network node, receiving an AF request including application steering information from an application function (AF), wherein the application steering information includes a keepExistingPSA indication indicating that a current data network access identifier (DNAI) and a current user plane (UP) path to the EAS should be maintained while a new DNAI and a new path to a new EAS are being established, and an indication indicating a period for maintaining the source PSA, generating a policy and charging control (PCC) rule based on the AF request, wherein the PCC rule includes the application steering information, providing the PCC rule to a session management function (SMF), a network node configured to perform the above.

13. The network node according to claim 12, wherein the network node is further configured to execute the method according to claim 10 or 11.

14. A method executed in a session management function (SMF) of a core network of a cellular communication system to enable simultaneous connection via a source protocol data unit session anchor (PSA) and a target PSA during relocation of an edge application server (EAS), receiving a policy and charging control (PCC) rule including application steering information from a policy control function (PCF), wherein the application steering information includes a keepExistingPSA indication indicating that a current data network access identifier (DNAI) and a current user plane (UP) path to the EAS should be maintained while a new DNAI and a new path to a new EAS are being established, and an indication indicating a period for maintaining the source PSA, Determining that a change from the source PSA to the target PSA of the PSA of a protocol data unit (PDU) session is to be executed; Determining, based on the keepExistingPSA indication, that a simultaneous connection via the source PSA and the target PSA is to be provided; Starting a timer for a time interval based on the indication for the period of maintaining the source PSA; Maintaining a source branch point (BP) or a source uplink classifier (UL CL) and a source user plane function (UPF) until the period of the timer elapses; Configuring the target PSA while maintaining a user plane (UP) connection to the current DNAI and the EAS via the source PSA; A method comprising.

15. The method according to claim 14, wherein The application steering information further includes an indication of a minimum time interval for considering the source BP / UP CL and the source UPF as inactive, The method further includes Starting an inactive timer for traffic passing through the source BP / UL CL and the source UPF, the inactive timer having a value greater than or equal to the minimum time interval; Removing the source BP / UL CL and the source UPF after an inactive period specified by the inactive timer; A method comprising.

16. A network node implementing a session management function (SMF) of a core network of a cellular communication system that enables a simultaneous connection via a source protocol data unit session anchor (PSA) and a target PSA during relocation of an edge application server (EAS), The network node is Receiving a policy and charging control (PCC) rule including application steering information from a policy control function (PCF), wherein the application steering information includes a keepExistingPSA indication indicating that the current data network access identifier (DNAI) and the current user plane (UP) path to the EAS should be maintained while a new path to a new DNAI and a new EAS is being established, and an indication indicating a period for maintaining the source PSA, Determining that a change from the source PSA to the target PSA of a protocol data unit (PDU) session is to be executed, Based on the keepExistingPSA indication, determining that a simultaneous connection via the source PSA and the target PSA is to be provided, Based on the indication of the period for maintaining the source PSA, starting a timer for a time interval, Maintaining a source branch point (BP) or a source uplink classifier (UL CL) and a source user plane function until the period of the timer has elapsed, Configuring the target PSA while maintaining the current DNAI and the user plane (UP) connection to the EAS via the source PSA, A network node configured to perform the above.

17. The network node according to claim 16, The network node is further configured to execute the method according to claim 15.

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