Mechanism for coordinating seamless service continuity to edge application servers at relocation

Abstract

Disclosed herein are methods and apparatuses for coordinating seamless service continuity to an edge application server, EAS, upon relocation in a cellular communications system. In some embodiments, an application function, AF, sends a steering request including a keepExistingPSA indication to a policy control function, PCF, the keepExistingPSA indication indicating that a current user plane, UP, path to a current data network access identifier, DNAI, and to the EAS should be maintained while establishing a new path to a new DNAI and the EAS. The PCF generates policy and charging control, PCC, rules including the keepExistingPSA indication, and provides the PCC rules to a session management function, SMF. The SMF determines, based on the keepExistingPSA indication, to provide a simultaneous connectivity over a source PSA and a target PSA, and configures the target PSA while maintaining the UP connectivity on the source PSA to the current DNAI and to the EAS.

Description

[0001] Related applications

[0002] This application claims the benefit of provisional patent application serial number 63 / 064,689, filed on August 12, 2020, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to maintaining service continuity during the relocation of an edge application server (EAS) in a cellular communication system. Background Technology

[0004] This disclosure relates to functionalities for supporting edge computing (EC) within the 3rd Generation Partnership Project (3GPP). The fifth-generation (5G) network architecture is defined by 3GPP Technical Specification (TS) 23.501. The roles of the network functions are defined as follows:

[0005] The Session Management Function (SMF) is responsible for session establishment, modification, and release (including the selection and control of User Plane Function (UPF) entities); maintaining the topology of the Packet Data Unit (PDU) Session Anchor (PSA) UPF involved; and establishing and releasing tunnels between the Access Network (AN) and the UPF, as well as between UPFs. The SMF also configures service forwarding at the UPF. The SMF interacts with the UPF at the N4 reference point using the Packet Forwarding Control Protocol (PFCP) procedure.

[0006] • User Plane Function (UPF) handles user data services. Among other functions, the UPF provides an external PDU session point for interconnection with the data network (DN) (e.g., PSA) and performs packet routing and forwarding (e.g., by supporting uplink classifiers (UL CL) to route traffic flows to instances of the DN, and / or supporting branch points to support multihomed PDU sessions).

[0007] The Policy Control Function (PCF) supports a unified policy framework for managing network behavior. Specifically, the PCF provides Policy and Charging Control (PCC) rules to the Policy and Charging Enforcement Function (PCEF) (i.e., the SMF / UPF that executes policy and charging decisions based on the provided PCC rules).

[0008] • Network Open Function (NEF) supports various functions, and particularly in the context of this disclosure, NEF acts as an entry point into the operator's network, enabling External Application Functions (AF).

[0009] (For example, content providers) can interact with the 3GPP core network through NEF.

[0010] • The AF sends requests to influence the SMF routing decisions for the services constituting a PDU session. AF requests can influence UPF selection or reselection and can allow user services to be routed via local access to the DN (e.g., identified by a Data Network Access Identifier or DNAI). The AF can communicate directly with the PCF in a Service-Based Architecture (SBA) domain or indirectly with the PCF through the NEF (i.e., using an Application Programming Interface (API) with the NEF to transmit AF communication to the PCF).

[0011] As described in Section 5.13 of 3GPP TS 23.501, EC enables operator and third-party services to be hosted near the attached User Equipment (UE) access point, achieving efficient service delivery through reduced end-to-end latency and load on the transport network. The 5G core network selects the UPF near the UE and performs service bootstrapping from the UPF to the local DN via the N6 interface. Section 5.13 of TS 23.501 also defines several enablers that support EC individually or in combination, including:

[0012] • User plane selection or reselection: The 5G core network selects or reselects the UPF to route user services to the local DN, as described in Section 6.3.3 of TS 23.501;

[0013] • Local routing and service guidance: The 5G core network selects services of applications to be routed to in the local DN, which may include using a single PDU session with multiple PDU session anchors (UL CL / IP v6 multihoming), as described in Section 5.6.4 of TS 23.501;

[0014] • Session and service continuity to enable UE and application mobility, as described in Section 5.6.9 of TS 23.501; and

[0015] • Application functions can influence UPF selection and reselection, as well as service routing via PCF or NEF, as described in more detail below.

[0016] The AF can send requests to influence SMF routing decisions for services in a PDU session. AF requests can affect UPF selection or reselection and can allow user services to be routed to local access to the DN. The DNAI is used to identify the location of local access to the DN. The AF can issue requests on behalf of applications not owned by the Public Land Mobile Network (PLMN) serving the UE. If the operator does not allow the AF to directly access the network, the AF interacts with the 5G Core (5GC) using the NEF.

[0017] The Application Controller (AF) can be responsible for the selection, reselection, and / or relocation of applications within the local DN. This functionality is not part of the 5GC but rather part of the application layer. To this end, the AF can request notification of events related to the PDU session, such as changes to the PDU session anchor. AF requests can be sent to the PCF (for a specific ongoing PDU session of an individual UE, if the AF is allowed to interact directly with the 5GC NF) or via the NEF. AF requests targeting multiple UEs or any UE's existing or future PDU sessions can be sent via the NEF, and can also target multiple PCFs. The PCF translates the AF request into a policy applicable to the PDU session.

[0018] When the AF has subscribed to UP path management event notifications (including notifications about how to reach the Common Public Subscription Identifier (GPSI) via N6) from the SMF, the SMF sends such notifications to the AF directly or via the NEF (not involving the PCF). The relevant procedures and the roles of the involved NFs are described in Section 4.6.3 of 3GPP TS23.502.

[0019] An AF request may contain the following information in part:

[0020] • Service Description (Mandatory): Defines the target service to be affected, represented by a combination of the Data Network Name (DNN), optional Single Network Slice Selection Auxiliary Information (S-NSSAI), and application identifier or service filtering information;

[0021] • Potential location of the application (conditional—may not exist only if the request is for subscribing to notifications): Indicates the potential location of the application, represented by a list of DNAIs; and

[0022] • Information about the AF subscription to the corresponding SMF event (optional): Indicates whether the AF subscribes to changes in the UP path of the PDU session and the parameters of the subscription.

[0023] Note that only items relevant to this disclosure are listed above. A more complete list can be found in Table 6.5.7-1 of TS 23.501.

[0024] The relevant scenarios disclosed herein involve providing session and service continuity to enable UE and application mobility. These methods may mean UP path management solutions for some existing PDU sessions in 5GC (e.g., changing an existing PSA or adding a new PSA). Detailed functionality of the current 5GC version 16 is described in section 4.3.5 of TS 23.502.

[0025] During the above process, runtime coordination between 5GC and AF may be achieved. To support this functionality, AF can include an "expect AF acknowledgment" indication in its requests. Based on this indication, when SMF sends early notification (including the corresponding source and target DNAIs) about changes to the UP path to be applied, SMF will not proceed until it receives a positive response from AF. This allows AF to take any necessary actions to maintain service continuity on the new path. Similarly, SMF can send a late notification to AF to inform AF of DNAI changes. For example, AF can use this notification to trigger a mechanism in the source local DN to redirect an ongoing service session to an application in the target local DN. SMF can activate the UP path toward the new DNAI until it receives a positive AF response. Summary of the Invention

[0026] This document discloses a method and apparatus for coordinating seamless service continuity to an Edge Application Server (EAS) during relocation in a cellular communication system. Specifically, it discloses an embodiment of a method for coordinating seamless service continuity to an EAS during relocation in a cellular communication system. In some embodiments, the method includes: at an Application Function (AF), sending a guidance request to a Policy Control Function (PCF) including application guidance information, the application guidance information including a keepExistingPSA indication indicating that while establishing new paths to a new Data Network Access Identifier (DNAI) and an EAS, the current User Plane Up (UP) paths to the current DNAI and the EAS should be maintained. The method further includes: at the PCF, receiving the guidance request from the AF; and based on the guidance request, generating a Policy and Charging Control (PCC) rule, wherein the PCC rule includes the application guidance information containing the keepExistingPSA indication. The method further includes: providing the PCC rule to a Session Management Function (SMF). The method further includes: at the SMF, receiving the PCC rule from the PCF. The method further includes: determining to perform a change to the PDU session anchor PSA for a Protocol Data Unit (PDU) session from the source PSA to the target PSA. The method further includes: determining, based on the keepExistingPSA indication, to provide simultaneous connectivity on both the source PSA and the target PSA. The method further includes: configuring the target PSA while maintaining UP connectivity on the source PSA with the current Data Network Access Identifier (DNAI) and with the EAS.

[0027] This document also discloses an embodiment of a method for coordinating seamless service continuity to an EAS during relocation in a cellular communication system. In some embodiments, the method includes: sending a guidance request from an AF to a PCF including application guidance information, the application guidance information including a keepExistingPSA indication indicating that while establishing new paths to the new DNAI and EAS, the current UP paths to the current DNAI and EAS should be maintained. Some embodiments disclosed herein provide that the application guidance information also includes a KeepExistingPSATimer indication indicating how long the previous PDU session anchor PSA should be maintained. According to some embodiments disclosed herein, the application guidance information also includes an indication of the minimum time interval to be considered for inactivity of the source branch point BP / uplink classifier UL CL.

[0028] In some embodiments disclosed herein, the application bootstrapping information also includes an indication of the minimum time interval to be considered for inactivity of the source user plane function UPF. Some embodiments disclosed herein provide a method that further includes: determining to perform an EAS change requiring a change to the DNAI; and invoking the Nnef_TrafficInfluence service including the application bootstrapping information. According to some embodiments disclosed herein, the method further includes: determining to perform an EAS change requiring a change to the DNAI; and sending one of an Npcf_PolicyAuthorization creation service request including the application bootstrapping information and an Npcf_PolicyAuthorization update service request including the application bootstrapping information.

[0029] This document also discloses an embodiment of a network node for implementing AF, wherein the AF is capable of coordinating seamless service continuity to EAS relocation during relocation in a cellular communication system. In some embodiments, the network node is adapted to send a guidance request to the PCF including application guidance information, the application guidance information including a keepExistingPSA indication indicating that while establishing new paths to the new DNAI and EAS, the current UP paths to the current DNAI and EAS should be maintained. Some embodiments disclosed herein may also provide that the network node is further adapted to perform any of the steps of the above methods attributed to the network node.

[0030] This document also discloses an embodiment of a network node for implementing AF, wherein the AF is capable of coordinating seamless service continuity to EAS during relocation in a cellular communication system. In some embodiments, the network node includes a network interface and processing circuitry associated with the network interface. The processing circuitry is configured to send a guidance request to the PCF including application guidance information, the application guidance information including a keepExistingPSA indication indicating that while establishing new paths to the new DNAI and EAS, the current UP paths to the current DNAI and EAS should be maintained. Some embodiments disclosed herein also provide that the processing circuitry is further configured to perform any of the steps of the above-described methods attributed to the network node.

[0031] This document also discloses an embodiment of a method for coordinating seamless service continuity to an EAS during relocation, executed in a PCF within the core network of a cellular communication system. In some embodiments, the method includes: receiving a guidance request from an AF including application guidance information, the application guidance information including a keepExistingPSA indication indicating that while establishing new paths to the new DNAI and EAS, the current UP paths to the current DNAI and EAS should be maintained. The method further includes: generating a PCC rule based on the guidance request, wherein the PCC rule includes the application guidance information. The method further includes: providing the PCC rule to the SMF. Some embodiments disclosed herein may also provide that the guidance request targets a new PDU session, and generating the PCC rule includes: generating the PCC rule during the establishment of the new PDU session. In some embodiments disclosed herein, the guidance request targets an ongoing PDU session, and generating the PCC rule includes: generating the PCC rule during the modification of the ongoing PDU session.

[0032] This document also discloses an embodiment of a network node for implementing a PCF (Process Control Function) in the core network of a cellular communication system, wherein the PCF is capable of coordinating seamless service continuity to the EAS (Electronic Access System) during relocation. In some embodiments, the network node is adapted to: receive a guidance request from an AF (Application Assistive Request) including application guidance information, the application guidance information including a keepExistingPSA (KeepExistingPSA) indication indicating that while establishing new paths to the new DNAI (Device Indicator) and the EAS (Electronic Access System), the current UP (Upstream Path) path to the current DNAI and the EAS should be maintained. The network node is further adapted to: generate a PCC (Process Control Code) rule based on the guidance request, wherein the PCC rule includes the application guidance information. The network node is further adapted to: provide the PCC rule to the SMF (Small and Medium-Sized Management Request). Some embodiments disclosed herein may also provide that the network node is further adapted to perform any of the steps of the above-described methods attributed to the network node.

[0033] This document also discloses an embodiment of a network node for implementing a PCF (Processing Component Filter) in the core network of a cellular communication system, wherein the PCF is capable of coordinating seamless service continuity to the EAS (Electronic Access System) during relocation. In some embodiments, the network node includes a network interface and processing circuitry associated with the network interface. The processing circuitry is configured to: receive a guidance request from an AF (Automatic Front-End Filter) including application guidance information, the application guidance information including a keepExistingPSA (KeepExistingPSA) indication indicating that while establishing new paths to the new DNAI (Device In-Service) and the EAS (Electronic Access System), the current UP (Upstream Path) path to the current DNAI and the EAS should be maintained. The processing circuitry is further configured to: generate a PCC (Process Control Component) rule based on the guidance request, wherein the PCC rule includes the application guidance information. The processing circuitry is further configured to: provide the PCC rule to the SMF (Small and Medium-Sized Filter). Some embodiments disclosed herein also provide that the processing circuitry is further configured to perform any of the steps of the above-described methods attributed to the network node.

[0034] This document also discloses an embodiment of a method for coordinating seamless service continuity to an EAS during relocation, executed in an SMF (System Function) within the core network of a cellular communication system. In some embodiments, the method includes: receiving a PCC (Programmable Continuity Control) rule from the PCF, wherein the PCC rule includes application guidance information, the application guidance information including a keepExistingPSA (KeepExistingPSA) indication indicating that while establishing new paths to the new DNAI (Device Indicator) and the EAS, the current UP (Uplink) path to the current DNAI and the EAS should be maintained. The method further includes: determining to perform a change to the PSA (Personal Status Ability) for a PDU (Programmable Dedicated Unit) session from a source PSA to a target PSA. The method further includes: determining, based on the keepExistingPSA indication, to provide simultaneous connectivity on the source PSA and the target PSA. The method further includes: configuring the target PSA while maintaining UP connectivity on the source PSA with the current DNAI and the EAS. Some embodiments disclosed herein also provide that the application boot information further includes a KeepExistingPSATimer indication, the KeepExistingPSATimer indication indicating how long a previous PSA will be maintained, and the method further includes: starting a timer of length one time interval based on the indication of how long the previous PSA will be maintained; and maintaining the source BP / UL CL and source UPF until the timer expires. In some embodiments disclosed herein, the application boot information further includes an indication of a minimum time interval to consider for inactivity of the source BP / UL CL and source UPF, and the method further includes: starting an inactivity timer for traffic through the source BP / UL CL and the source UPF, wherein the inactivity timer has a value equal to or greater than the minimum time interval; and removing the source BP / UL CL and the source UPF after an inactivity period specified by the inactivity timer.

[0035] This document also discloses an embodiment of a network node for implementing an SMF (Service Provider Function) for a core network of a cellular communication system, wherein the SMF is capable of coordinating seamless service continuity during EAS (Electronic Access System) relocation. In some embodiments, the network node is adapted to: receive PCC (Plan-Do-Check-Act) rules from a PCF (Plan-Do-Check-Act) system, wherein the PCC rules include application guidance information, the application guidance information including a keepExistingPSA (KeepExistingPSA) indication, which indicates that while establishing new paths to the new DNAI (Device Intended for Access) and the EAS (Electronic Access System), the current UP (Uplink) path to the current DNAI and the EAS should be maintained. The network node is further adapted to: determine to perform a change in the PSA (Personal Access System) for a PDU (Programmable Dedicated Unit) session from the source PSA to the target PSA. The network node is further adapted to: determine, based on the keepExistingPSA indication, to provide simultaneous connectivity on the source PSA and the target PSA. The network node is further adapted to: configure the target PSA while maintaining UP connectivity on the source PSA with the current DNAI and with the EAS. Some embodiments disclosed herein may also provide that the network node is further adapted to perform any of the steps described above attributable to the network node.

[0036] This document also discloses an embodiment of a network node for implementing an SMF (Service Provider) in a core network for a cellular communication system, wherein the SMF is capable of coordinating seamless service continuity during EAS (Electronic Access System) relocation. In some embodiments, the network node includes a network interface and processing circuitry associated with the network interface. The processing circuitry is configured to: receive PCC (Process Control Code) rules from a PCF (Processing Provider Code), wherein the PCC rules include application guidance information, the application guidance information including a keepExistingPSA (KeepExistingPSA) indication, the keepExistingPSA indication indicating that while establishing new paths to the new DNAI (Device Institution) and the EAS (Electronic Access System), the current UP (Uplink) path to the current DNAI and the EAS should be maintained. The processing circuitry is further configured to: determine to perform a change to the PSA (Personal Access System) for a PDU (Programmable Dedicated Unit) session from the source PSA to the target PSA. The processing circuitry is further configured to: determine, based on the keepExistingPSA indication, to provide simultaneous connectivity on the source PSA and the target PSA. The processing circuitry is further configured to: configure the target PSA while maintaining UP connectivity on the source PSA with the current DNAI and the EAS. Some embodiments disclosed herein also provide that the processing circuitry is configured to perform any of the above-described methods attributed to the network node. Attached Figure Description

[0037] Several aspects of this disclosure are illustrated in conjunction with the accompanying drawings, which are incorporated in and form a part of this specification, and together with the specification serve to explain the principles of this disclosure.

[0038] Figure 1 An example of a cellular communication system according to some embodiments of the present disclosure is shown;

[0039] Figure 2 and 3 It shows that Figure 3 The cellular communication system is an example implementation of the fifth-generation (5G) system (5GS);

[0040] Figure 4A and 4B Exemplary communication flows and operations for 5G core (5GC) triggered edge application server (EAS) relocation according to some embodiments disclosed herein are illustrated;

[0041] Figure 5A and 5B Exemplary communication flows and operations performed when an application triggers edge relocation, according to some embodiments disclosed herein, are illustrated;

[0042] Figure 6 This is a schematic block diagram of a radio access node according to some embodiments of the present disclosure;

[0043] Figure 7 This illustrates some embodiments according to the present disclosure. Figure 6 A schematic block diagram of a virtualization embodiment of a radio access node; and

[0044] Figure 8 It is based on some other embodiments of this disclosure Figure 6 A schematic block diagram of a radio access node. Detailed Implementation

[0045] The embodiments described below illustrate information that enables those skilled in the art to practice the embodiments and demonstrate the best mode for practicing the embodiments. By reading the following description in conjunction with the accompanying drawings, those skilled in the art will understand the concepts of this disclosure and will recognize the application of these concepts not specifically mentioned herein. It should be understood that these concepts and applications fall within the scope of this disclosure.

[0046] Existing methods currently present certain challenges. Section 4.3.5.7 of TS 23.502 describes a procedure for "simultaneously changing the branch point or UL CL for a PDU session and the attached PSA". In the description of this procedure, the status of step 10 is shown in Table 1 below:

[0047] Table 1

[0048]

[0049] However, the standard lacks indication regarding how the SMF knows whether to use session continuity during UL CL relocation. While 5GC may have internal policy settings to determine this, it's not possible for the AF side to dynamically control whether session continuity should be used (e.g., for a given application or application session). Therefore, it would be desirable if the AF could control whether session continuity should be used during UL CL relocation for a specific PDU session.

[0050] In addition, as noted in Note 7 of the referenced 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 how long the old UP path and the new UP path should coexist.

[0051] Therefore, specific aspects and embodiments thereof in this disclosure can provide solutions to the above-described or other challenges. Various embodiments are presented herein to address one or more of the problems disclosed herein. Systems and methods for coordinating seamless service continuity to EAS during relocation are proposed, providing solutions to the above-described or other challenges.

[0052] In some embodiments, edge relocation-related preferences are transmitted by the AF and sent along with the AF's impact on service routing. This information will include an indication of whether session continuity should be used when UL CL relocation is changed simultaneously with the application of UL CL and PSA, and for how long UL CL relocation should be used for session continuity.

[0053] Specific embodiments can provide one or more of the following technical advantages. In particular, this solution allows 5GC to further enhance AF control over service routing in a manner that achieves service continuity for EC services, enabling more informed decisions that better adapt to real-world application needs.

[0054] Before discussing in more detail the methods and apparatus for re-anchoring using SMF reselection, exemplary cellular communication systems in which some embodiments of this disclosure can be implemented are first discussed. In this regard, the following terms are defined:

[0055] Radio node: As used in this article, a “radio node” is a radio access node or wireless communication device.

[0056] Radio Access Node: As used herein, a “radio access node” or “radio network node” or “radio access network node” is any node in the radio access network (RAN) of a cellular communication network used for wirelessly transmitting and / or receiving signals. Some examples of radio access nodes include, but are not limited to, base stations (e.g., new radio (NR) base stations (gNBs) in 3GPP 5G NR networks or enhanced or evolved Node Bs (eNBs) in 3GPP LTE networks), 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 that implement some of the functions of a base station (e.g., network nodes that implement a gNB central unit (gNB-CU) or a gNB distributed unit (gNB-DU),) or network nodes that implement some of the functions of other types of radio access nodes.

[0057] Core Network Node: As used herein, a “core network node” is any type of node in the core network or any node that implements core network functions. Some examples of core network nodes include, for example, Mobility Management Entities (MMEs), Packet Data Network Gateways (P-GWs), Service Capability Opening Functions (SCEFs), Home Subscriber Servers (HSSs), etc. Other examples of core network nodes include nodes that implement Access and Mobility Management Functions (AMFs), User Plane Functions (UPFs), Session Management Functions (SMFs), Authentication Server Functions (AUSFs), Network Slice Selection Functions (NSSFs), Network Opening Functions (NEFs), Network Functions (NF) Repository Functions (NRFs), Policy Control Functions (PCFs), Unified Data Management (UDMs), etc.

[0058] Communication equipment: As used herein, “communication equipment” is any type of device that accesses a network. Some examples of communication equipment include, but are not limited to: mobile phones, smartphones, sensor devices, instruments, vehicles, home appliances, medical devices, media players, cameras, or any type of consumer electronics, such as, but not limited to, televisions, radios, lighting fixtures, tablets, laptops, or personal computers (PCs). Communication equipment can be portable, handheld, computer-integrated, or in-vehicle mobile devices capable of transmitting voice and / or data via wireless or wired connections.

[0059] Wireless communication device: One type of communication device is a wireless communication device, which can be any type of wireless device that accesses a wireless network (such as a cellular network) (i.e., is served by it). Some examples of wireless communication devices include, but are not limited to: User Equipment (UE), Machine-Type Communication (MTC) devices, and Internet of Things (IoT) devices in 3GPP networks. Such wireless communication devices can be or can be integrated into: mobile phones, smartphones, sensor devices, instruments, vehicles, home appliances, medical devices, media players, cameras, or any type of consumer electronics, such as, but not limited to, televisions, radios, lighting fixtures, tablets, laptops, or PCs. Wireless communication devices can be portable, handheld, computer-integrated, or in-vehicle mobile devices capable of transmitting voice and / or data via a wireless connection.

[0060] 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.

[0061] Note that the descriptions presented herein focus on 3GPP cellular communication systems, and therefore, 3GPP terminology or similar terms are frequently used. However, the concepts disclosed herein are not limited to 3GPP systems.

[0062] Note that the term “cell” may be referenced in the description herein; however, in particular with respect to the 5G NR concept, beam may be used instead of cell, and therefore it is important to note that the concepts described herein apply equally to both cell and beam.

[0063] Figure 1An example of a cellular communication system 100 in which embodiments of the present disclosure may be implemented is shown. 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 in the 5GS include NR base stations (gNB) and optional next-generation eNBs (ng-eNBs) (e.g., LTE RAN nodes connected to the 5GC), and in the EPS include eNBs that control corresponding (macro)cells 104-1 and 104-2. Base stations 102-1 and 102-2 are generally referred to herein collectively as base station 102 and individually as base station 102. Similarly, (macro)cells 104-1 and 104-2 are generally referred to herein as (macro)cell 104 and individually as (macro)cell 104. The RAN may also include multiple low-power nodes 106-1 to 106-4, which control corresponding small cells 108-1 to 108-4. Low-power nodes 106-1 to 106-4 may be small base stations (e.g., pico or femtocells) or remote radio head units (RRHs), etc. It is noteworthy that, although not shown, one or more of small cells 108-1 to 108-4 may alternatively be provided by base station 102. Low-power nodes 106-1 to 106-4 are generally referred to herein as low-power node 106 and individually as low-power node 106. Similarly, small cells 108-1 to 108-4 are generally referred to herein as small cell 108 and individually as small cell 108. The cellular communication system 100 also includes a core network 110, which is referred to as 5GC in a 5G system (5GS). Base station 102 (and optional low-power node 106) are connected to the core network 110.

[0064] Base station 102 and low-power node 106 provide services to wireless communication devices 112-1 to 112-5 in corresponding cells 104 and 108. Wireless communication devices 112-1 to 112-5 are generally referred to herein as wireless communication device 112, and individually as wireless communication device 112. In the following description, wireless communication device 112 is often a UE, but this disclosure is not limited thereto.

[0065] Figure 2 A wireless communication system is shown that is represented as a 5G network architecture including core network functions (NFs), where the interaction between any two NFs is represented by a point-to-point reference point / interface. Figure 2 Can be regarded as Figure 1 A specific implementation of System 100.

[0066] From the access side, Figure 2 The 5G network architecture shown includes multiple UEs 112 connected to RAN 102 or the access network (AN) and AMF 200. Typically, RAN 102 includes base stations such as eNBs or gNBs. From the core network side, Figure 2 The 5GC NF shown includes NSSF 202, AUSF 204, UDM 206, AMF 200, SMF 208, PCF 210 and Application Function (AF) 212.

[0067] The reference points in the 5G network architecture are used to define detailed call flows in the standardization process. Reference point N1 is defined to carry signaling between UE 112 and AMF 200. Reference points used for connections between RAN 102 and AMF 200, and between RAN 102 and UPF 214, are defined as N2 and N3, respectively. Reference point N11 exists between AMF 200 and SMF 208, meaning that SMF 208 is at least partially controlled by AMF 200. N4 is used by SMF 208 and UPF 214 to allow UPF 214 to be set up using control signals generated by SMF 208, and UPF 214 to report its status to SMF 208. Specifically, N9 is a reference point for connections between different UPF 214s, while N14 is a reference point for connections between different AMF 200s. N15 and N7 are defined because PCF 210 applies policies to AMF 200 and SMF 208 respectively. AMF 200 requires N12 to perform authentication for UE 112. N8 and N10 are defined because AMF 200 and SMF 208 require subscription data from UE 112.

[0068] The 5GC network aims to separate the user plane (UP) and control plane (CP). The UP carries user traffic, while the CP carries network signaling. Figure 2 In this architecture, UPF 214 resides in the UP (Upplane), while all other NFs (i.e., AMF 200, SMF 208, PCF 210, AF212, NSSF 202, AUSF 204, and UDM 206) reside in the CP (Plane Center). Separating the UP and CP ensures that each plane resource is scaled independently. It also allows the UPF to be deployed in a distributed manner, separate from the CP functionality. In this architecture, for some low-latency applications, the UPF can be deployed very close to the UE to reduce the round-trip time (RTT) between the UE and the data network.

[0069] The core 5G network architecture includes modular functions. For example, AMF 200 and SMF 208 are independent functions within the CP (Content Provider Interface). The phase-separated nature of AMF 200 and SMF 208 allows for independent evolution and scaling. Other CP functions (such as PCF 210 and AUSF 204) can be... Figure 2 As shown in the diagram, the modular functional design allows the 5GC network to flexibly support a variety of services.

[0070] Each NF interacts directly with every other NF. Intermediate functions can be used to route messages from one NF to another. In CP, a set of interactions between two NFs is defined as a service to make service reuse possible. This service implementation supports modularity. UP supports interactions such as forwarding operations between different UPFs.

[0071] Figure 3 This demonstrates a service-based interface between NFs in CP instead of... Figure 2 The 5G network architecture uses a point-to-point reference point / interface. However, the above reference... Figure 2 The NF described corresponds to Figure 3 The NF shown can provide services to other authorized NFs through service-based interfaces. Figure 3 In this context, service-based interfaces are indicated by the letter "N" followed by the name of the NF, such as Namf for the service-based interface of AMF 200, Nsmf for the service-based interface of SMF 208, and so on. Figure 3 The NEF 300 and NRF 302 mentioned above are not discussed above. Figure 2 As shown in the image. However, it should be clarified that... Figure 2 All NFs described in the text can be used with... Figure 3 The NEF 300 and NRF302 interact, although in Figure 2 It is not explicitly stated in the text.

[0072] Figure 2 and Figure 3Some characteristics of the NF shown can be described as follows. AMF200 provides UE-based authentication, authorization, mobility management, etc. Even if UE 112 uses multiple access technologies, it is essentially connected to a single AMF 200 because the AMF 200 is technology-independent. SMF 208 is responsible for session management and can assign Internet Protocol (IP) addresses to UEs. It also selects and controls UPF 214 for data transmission. If UE 112 has multiple sessions, a different SMF 208 can be assigned to each session to manage the session individually, and different functions may be provided according to the session. AF 212 provides information about packet flows to PCF 210, which is responsible for policy control, to support QoS. Based on this information, PCF 210 determines policies regarding mobility and session management to ensure that AMF 200 and SMF 208 function correctly. AUSF 204 supports authentication functions for UEs, etc., and therefore stores data used for authenticating UEs, etc., while UDM 206 stores UE 112's subscription data. Data networks (DNs) (which are not part of the 5GC network) provide internet access or carrier services, etc. NFs can be implemented as network units on dedicated hardware, as software instances running on dedicated hardware, or as virtualization functions instantiated on appropriate platforms (such as cloud infrastructure).

[0073] As described above, this paper discloses a system and method for coordinating seamless service continuity to EAS during relocation. The solution addresses the impact of AF on service routing and thus affects two (2) service operations:

[0074] • When the AF request targets a separate UE address that needs to be received by the relevant PCF, this instruction should be sent in the Npcf_PolicyAuthorization creation / update service request. The AF sends the AF request directly to the PCF and then directly invokes Npcf_PolicyAuthorization, or NEF invokes Npcf_PolicyAuthorization (see Section 4.3.6.4 of TS23.502).

[0075] • When an AF request is not identified by the UE Internet Protocol (IP) address, the indication is sent to the NEF in the Nnef_TrafficInfluence_Create or Update request (see Section 4.3.6.2 of TS 23.502), stored in the UDR, and the PCF will receive the indication when needed.

[0076] There are two potential triggers for application relocation, which could mean sending the above message:

[0077] • Application server changes are triggered by the 5GC wanting to modify the UE's local PSA. This may occur due to factors such as UE mobility. This change in the UP path can be notified to the application server side via user plane management notifications of PSA relocation / DNAI changes through the AF.

[0078] • Application server changes are initiated from the application side (e.g., for load rebalancing, due to congestion on the edge application servers being served). In this case,

[0079] The role of 5GC is to ensure connectivity with the new EAS by establishing appropriate UL CL / BP and local PSA.

[0080] The following are example procedures for two scenarios.

[0081] Figure 4A and 4B The operation for EAS relocation triggered by 5GC is illustrated. The following procedure assumes that runtime coordination between 5GC and the application (AF) is enabled. This coordination provides notification and control of the old and new UL CL / BP and the local PSA. The following provides... Figure 4A and 4B The process is described in the diagram.

[0082] exist Figure 4A In step 401, before or during edge application connection, the AF may send a request to influence the service routing of the session or the individual UE address (see sections 4.3.6.2 and 4.6.3.4 of TS 23.502). This request provides service filters, DNAI, and N6 service routing information. Application guidance information may be provided by other means (e.g., as part of a Service Level Agreement (SLA) and as needed; see, for example, solution #3 in TR 23.748). Additionally, a subscription to a DNAI change notification is sent to the core network, which includes the application's domain name and an "expected AF acknowledgment" indication. This process is similar to steps 1-4 as defined in section 4.3.6.2 of TS 23.502.

[0083] In addition, the AF also includes a new keepExistingPSA indication in the boot request. This new keepExistingPSA indication indicates that, in the event of a change of the UP path to a specified DNAI, the existing UP path should also be temporarily maintained for the UE during and after the establishment of the new UP path (i.e., session continuity when using UL CL relocation). In some embodiments, the AF may also provide input regarding how long the previous PSA should be maintained. According to some embodiments, the AF may use a KeepExistingPSATimer indication to indicate the minimum time interval to be considered for inactivity of the previous path.

[0084] In step 402, the PCF generates PCC rules based on the AF request and provides the PCC rules to the SMF. The PCC rules also include keepExistingPSA instructions and additional information. This step can occur during PDU session establishment or modification, depending on whether the request targets an ongoing PDU session. Assume that an edge application connection is established using one of the mechanisms proposed for EAS discovery and selection (e.g., solution #3 in TR 23.748). Initially, traffic flows to the legacy EAS via a source BP / UL CL and a source UPF (PSA2) established based on the PCC rules for that application.

[0085] In step 403, the SMF determines that the source BP / UL CL and source UPF (PSA2) need to be relocated. Relocation can be triggered by UE mobility.

[0086] In step 404, based on the AF subscription, the SMF sends an early notification to the AF, including the corresponding source and target DNAI. The SMF does not proceed until it receives a positive response from the AF, as described in Section 5.6.7 of TS 23.501.

[0087] 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 the application server needs to be relocated, and the AF determines the new edge AS.

[0088] In step 406, the AF sends the Nsmf_EventExposure_AppRelocationInfo service operation to the UE's SMF, as described in section 4.3.6.3 of TS 23.502. Note that the old EAS is still handling edge application connections at this point (but the instantiation and context migration of the new EAS may have been initiated). In this message, the AF acknowledges the notification and can provide N6 service routing information associated with the target DNAI.

[0089] In step 407, the SMF determines that for this session, it needs to perform simultaneous changes to the BP or UL CL for the PDU session, along with an additional PSA (as described in section 4.3.5.7 of TS 23.502). The SMF infers session continuity for UL CL relocation from the keepExistingPSA instruction in the PCC rules, establishes the target BP / UL CL and target UPF (PSA2) determined in step 403, and configures the filter based on the already available boot information (see step 401). To support session continuity during UL CL relocation and EAS migration, a temporary N9 forwarding 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) will be maintained for a period of time, and a timer is started with values ​​that take into account information received from the AF.

[0090] In some embodiments, the SMF can set an inactivity timer for traffic via the source BP / UL CL and source UPF (PSA2) to remove the source BP / UL CL and source UPF after an inactivity period. The value of the inactivity timer is equal to or greater than any minimum time interval (if any) to be considered for inactivity of a previous path provided by the AF (i.e., all active traffic flowing on that previous path no longer exists within the configurable time period). According to some embodiments, the AF can send an explicit notification that the previous connection is no longer needed.

[0091] In step 408, after the target BP / UL CL and target UPF (PSA3) have been provided (see steps 2-8 in Figure 4.3.5.7-1 of TS 23.502), the SMF sends an event opening (i.e., delay notification) to the AF regarding the new UP path. If this notification is forwarded to the NEF, the NEF converts it into an Nnef_TraffcInfluence_Notify to the AF, as specified in section 4.3.6.3 of TS 23.502. Note that UE traffic can still reach the old EAS via the source BP / UL CL and source UPF (PSA2). This is particularly useful when EAS relocation is being completed and allows for a switch to the new EAS when it is more suitable for the application. Then... Figure 4B Continue the operation.

[0092] Now for reference Figure 4B In step 409, the context transfer between the old EAS and the new EAS is completed. Note that this step can occur at any time after step 405 and can be performed before steps 406-408.

[0093] In step 410, after completing both steps 408 and 409, an application-layer procedure is used to instruct the application client when and how to switch to the new EAS. Instructions on how to continue can be sent to the application client (e.g., continue using the old EAS, send services to both, or some other application-specific procedure). Any service heading to the new EAS passes through the target BP / UL CL and target UPF (PSA3) as provided in step 407. UE application services begin arriving at the new EAS along the path through the target BP / UL CL and target UPF (PSB3).

[0094] In step 411, after the timer started in step 407 expires, the SMF removes the source BP / UL CL and the source UPF (PSA2).

[0095] Figure 5A and 5B The diagram illustrates the actions performed when an application triggers edge relocation. It assumes that the AF (Application Front-End) can obtain information about whether EAS relocation is needed based on notifications from, for example, the edge application itself, the application layer management system, or another system. The AF also receives information about the target DNAI, the UE IP address of the ongoing PDU session affected by the EAS relocation, and the target EAS-related IP address.

[0096] When EAS changes do not involve changes to DNAI, EAS changes can be handled entirely by the application layer (e.g., following the above guidelines for...). Figure 4A and 4B Steps 409, 410, and 411 in the described process. When EAS changes involve altering the DNAI, the EAS changes need to be processed in coordination with 5GC as described in the following process:

[0097] exist Figure 5A In the middle, steps 501 and 502 are the same as those above. Figure 4A and 4B The steps described are the same, and result in connecting the application to the legacy EAS via source BP / UL CL and source UPF (PSA2).

[0098] In step 503, AF can determine that an EAS change is required, which necessitates a change to the DNAI.

[0099] In step 504, if the influence is via NEF, the AF invokes the Nnef_TrafficInfluence service for each individual UE IP address, or, as described in section 4.3.6.4 of TS 23.502, sends an Npcf_PolicyAuthorization create / update service request using the BSF to locate the PCF for each individual UE. The AF also includes a new keepExistingPSA indication and time information in this message (if this has not been done in step 501).

[0100] In some embodiments, optimization steps can be used to reduce the signaling requirements of step 506, since application-triggered server relocation events can typically involve multiple UEs. In step 506, the AF invokes the Nnef_TrafficInfluence service, as described in section 4.3.6.2 of TS 23.502, where the DNAI specifies the target UE identifier, and the service descriptor further narrows down the target services to be affected (represented by a combination of the DNN and optional S-NSSAI, along with the application identifier or service filtering information).

[0101] In step 505, the PCF then triggers a PCC update to the SMF for the target DNAI for a given PDU session (as in step 503).

[0102] 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 UPF.

[0103] In step 507, the early notification from SMF to AF can trigger EAS relocation.

[0104] Steps 508-513 are the same as those above. Figure 4A and 4B The steps discussed are the same as 406-411.

[0105] Figure 6This is a schematic block diagram of a network node 600 according to some embodiments of the present disclosure. Optional features are indicated by dashed boxes. The network node 600 may be a network node that implements all or part of the functionality of an NF (e.g., SMF or PCF) or AF, as described herein, for example, according to any embodiment. As shown, the network node 600 includes one or more processors 604 (e.g., a central processing unit (CPU), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), etc.), memory 606, and a network interface 608. The one or more processors 604 are also referred to herein as processing circuitry. 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, these functions are implemented in software stored, for example, in memory 606 and executed by the one or more processors 604.

[0106] Figure 7 This is a schematic block diagram illustrating a virtualized embodiment of a 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 implemented as a virtual component (e.g., via a virtual machine executing on a physical processing node in the network). As shown, in this example, network node 600 includes one or more processing nodes 700 coupled to or included as part of network 702. Each processing node 700 includes one or more processors 704 (e.g., CPU, ASIC, FPGA, etc.), memory 706, and network interface 708.

[0107] In this example, the functionality 710 of the network node 600 described herein (e.g., one or more functions of the NF (e.g., SMF or AMF) or AF described herein) is implemented at one or more processing nodes 700, or distributed across two or more processing nodes 700 in any desired manner. In some specific embodiments, some or all of the functionality 710 of the network node 600 described herein is implemented as virtual components executed by one or more virtual machines implemented in a virtual environment hosted by the processing node 700.

[0108] In some embodiments, a computer program including instructions is provided that, when executed by at least one processor, cause at least one processor to perform the functions of network node 600 or a node (e.g., processing node 700) that implements one or more functions 710 of network node 600 in a virtual environment according to any embodiment described herein. In some embodiments, a carrier including the aforementioned computer program product is provided. The carrier is one of an electrical signal, an optical signal, a radio signal, or a computer-readable storage medium (e.g., a non-transitory computer-readable medium such as a memory).

[0109] Figure 8 This is a schematic 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 implemented in software. Modules 800 provide the functionality of the network node 600 described herein (e.g., one or more of the functionality of the NF (e.g., SMF or AMF) or AF described herein). This discussion also applies to... Figure 7 The processing node 700, wherein the module 800 may be implemented at one of the processing nodes 700 or distributed across multiple processing nodes 700.

[0110] Any suitable steps, methods, features, functions, or benefits disclosed herein can be performed by one or more functional units or modules of one or more virtual devices. Each virtual device may include multiple such functional units. These functional units may be implemented via processing circuitry that may include one or more microprocessors or microcontrollers and other digital hardware that may include digital signal processors (DSPs), dedicated digital logic, etc. The processing circuitry may be configured to execute program code stored in 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 memory includes program instructions for executing one or more telecommunications and / or data communication protocols and instructions for executing one or more technologies described herein. In some implementations, the processing circuitry may be used to cause corresponding functional units to perform corresponding functions according to one or more embodiments of this disclosure.

[0111] Although the processes in the figures may illustrate a particular order of operations performed in a particular embodiment of this disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform operations in a different order, combine particular operations, overlap particular operations, etc.).

[0112] Although not limited thereto, some example embodiments of this disclosure are provided below.

[0113] Example 1. A method for coordinating seamless service continuity during edge application server (EAS) relocation, executed in the core network of a cellular communication system, the method comprising:

[0114] • At the application function AF:

[0115] ο Send a boot request to the Policy Control Function (PCF) including application boot information, which includes a keepExistingPSA instruction. The keepExistingPSA instruction indicates that while establishing new paths to the new Data Network Access Identifier (DNAI) and Edge Application Server (EAS), the current User Plane UP path to the current DNAI and the current EAS should be maintained.

[0116] • At PCF:

[0117] ο Receive boot request from AF;

[0118] Based on the bootstrapping request, policy and charging control (PCC) rules are generated, including application bootstrapping information; and

[0119] Provide PCC rules to the Session Management Function (SMF); and

[0120] • At SMF:

[0121] ο Receive PCC rules from PCF;

[0122] ο Determine whether to perform changes to the branch point BP or ULCL and the additional PDU session anchor PSA for the Protocol Data Unit (PDU) session;

[0123] Based on the keepExistingPSA instruction, determine session continuity when using UL CL relocation; and

[0124] Configure the target BP or UL CL and the target user plane function UPF.

[0125] Example 2. A method for coordinating seamless service continuity during edge application server (EAS) relocation, executed in an application function (AF) in the core network of a cellular communication system, the method comprising: sending a guidance request to a policy control function (PCF) including application guidance information, the application guidance information including a keepExistingPSA indication, the keepExistingPSA indication indicating that while establishing new paths to the new data network access identifier (DNAI) and the edge application server (EAS), the current user plane up paths to the current DNAI and the current user plane up paths to the EAS should be maintained.

[0126] Example 3. According to the method of Example 2, the application guidance information further includes an indication of how long to maintain the previous Protocol Data Unit (PDU) Session Anchor (PSA).

[0127] Example 4. According to the method of Example 2, the application guidance information further includes an indication of the minimum time interval to be considered for inactivity of the source branch point BP / uplink classifier UL CL and the source user plane function UPF.

[0128] Example 5. The method according to Example 2 further includes:

[0129] • Determine if an EAS change requiring a change to the DNAI needs to be performed; and

[0130] • Invoke the Nnef_TrafficInfluence service, which includes application boot information, where DNAI specifies one or more target user equipment (UE) identifiers.

[0131] Example 6. The method according to Example 2 further includes:

[0132] • Determine if an EAS change requiring a change to the DNAI needs to be performed; and

[0133] • Send an Npcf_PolicyAuthorization service creation request or an Npcf_PolicyAuthorization service update request, which includes application guidance information.

[0134] Example 7. An application function (AF) of the core network of a cellular communication system, wherein the AF is capable of coordinating seamless service continuity during edge application server (EAS) relocation, the AF being adapted to: send a guidance request including application guidance information to a policy control function (PCF), the application guidance information including a keepExistingPSA indication, the keepExistingPSA indication indicating that while establishing new paths to the new data network access identifier (DNAI) and edge application server (EAS), the current user plane up path to the current DNAI and to the current EAS should be maintained.

[0135] Example 8. The AF according to Example 7, wherein the AF is also adapted to perform the method according to any one of Examples 2 to 6.

[0136] Example 9. A network node for implementing Application Functions (AF) of the core network for a cellular communication system, wherein the AF is capable of coordinating seamless service continuity during Edge Application Server (EAS) relocation, the network node comprising:

[0137] • Network interface; and

[0138] • Processing circuitry associated with the network interface, the processing circuitry being adapted to enable the network node to implement AF, such that the AF is configured to: send a boot request to the Policy Control Function (PCF) including application boot information, the application boot information including a keepExistingPSA indication, the keepExistingPSA indication indicating that while establishing new paths to the new Data Network Access Identifier (DNAI) and Edge Application Server (EAS), the current User Plane Up (UP) paths to the current DNAI and EAS should be maintained.

[0139] Example 10. The network node according to Example 9, wherein the AF is also adapted to perform the method according to any one of Examples 2 to 6.

[0140] Example 11. A method for coordinating seamless service continuity during Edge Application Server (EAS) relocation, executed in the Policy Control Function (PCF) of the core network of a cellular communication system, the method comprising:

[0141] • Receive a setup request from the application function AF, which includes application setup information, including a keepExistingPSA indication, which indicates that session continuity should be maintained during uplink classifier UL CL relocation.

[0142] Based on the bootstrapping request, generate policy and charging control (PCC) rules, which include application bootstrapping information; and

[0143] • Provide PCC rules to the Session Management Function (SMF).

[0144] Example 12. The method according to Example 11, wherein:

[0145] • The bootstrapping request targets a new PDU session; and

[0146] • Execute the PCC rule generation during the establishment of a new PDU session.

[0147] Example 13. The method according to Example 11, wherein:

[0148] • The bootstrapping request targets an ongoing PDU session; and

[0149] • Execute the generation of PCC rules during the modification of an ongoing PDU session.

[0150] Example 14. A policy control function (PCF) for the core network of a cellular communication system, wherein the PCF is capable of coordinating seamless service continuity during edge application server (EAS) relocation, and the PCF is suitable for:

[0151] • Receive a setup request from the application function AF, which includes application setup information, including a keepExistingPSA indication, which indicates that session continuity should be maintained during uplink classifier UL CL relocation.

[0152] Based on the bootstrapping request, generate policy and charging control (PCC) rules, which include application bootstrapping information; and

[0153] • Provide PCC rules to the Session Management Function (SMF).

[0154] Example 15. The PCF according to Example 14, wherein the PCF is also adapted to perform the method according to any one of Examples 12 and 13.

[0155] Example 16. A network node for implementing Policy Control Function (PCF) for a core network of a cellular communication system, wherein the PCF is capable of coordinating seamless service continuity during Edge Application Server (EAS) relocation, the network node comprising:

[0156] • Network interface; and

[0157] • Processing circuitry associated with the network interface, adapted to enable the network node to implement PCF, such that PCF is configured as follows:

[0158] ο Receive a setup request from the application function AF, which includes application setup information, including a keepExistingPSA indication, which indicates that session continuity should be maintained during uplink classifier UL CL relocation.

[0159] Based on the bootstrapping request, policy and charging control (PCC) rules are generated, including application bootstrapping information; and

[0160] Provide PCC rules to the Session Management Function (SMF).

[0161] Example 17. A network node according to Example 16, wherein the AF is also adapted to perform the method according to any one of Examples 12 and 13.

[0162] Example 18. A method for coordinating seamless service continuity during Edge Application Server (EAS) relocation, executed in the Session Management Function (SMF) of the core network of a cellular communication system, the method comprising:

[0163] • Receive policy and charging control (PCC) rules from the policy control function (PCF). The PCC rules include application bootstrapping information, which includes a keepExistingPSA instruction. The keepExistingPSA instruction indicates that session continuity should be maintained during uplink classifier ULCL relocation.

[0164] • Determine whether to perform changes simultaneously for the branch point BP or UL CL and the additional PDU session anchor PSA for the Protocol Data Unit (PDU) session;

[0165] • Based on the keepExistingPSA instruction, determine session continuity when using UL CL relocation; and

[0166] • Configure the target BP or UL CL and the target user face function UPF.

[0167] Example 19. The method according to Example 18, wherein:

[0168] The application guidance information also includes instructions on how long to maintain the previous PSA; and

[0169] The method also includes:

[0170] Based on an indication of how long to maintain the previous PSA, a timer with a length of one time interval is started; and

[0171] Maintain source BP / UL CL and source UPF until the timer expires.

[0172] Example 20. The method according to Example 18, wherein:

[0173] • The application guidance information also includes an indication of the minimum time interval to be considered for inactivity of the source BP / UL CL and source UPF; and

[0174] The method also includes:

[0175] ο Inactive timers are started for services transmitted via source BP / UL CL and source UPF, wherein the inactive timers have a value equal to or greater than the minimum time interval; and

[0176] After the inactivity period specified by the inactivity timer, remove the source BP / UL CL and source UPF.

[0177] Example 21. A Session Management Function (SMF) for the core network of a cellular communication system, wherein the SMF is capable of coordinating seamless service continuity during Edge Application Server (EAS) relocation, and the SMF is suitable for:

[0178] • Receive policy and charging control (PCC) rules from the policy control function (PCF). The PCC rules include application bootstrapping information, which includes a keepExistingPSA instruction. The keepExistingPSA instruction indicates that session continuity should be maintained during uplink classifier ULCL relocation.

[0179] • Determine whether to perform changes simultaneously for the branch point BP or UL CL and the additional PDU session anchor PSA for the Protocol Data Unit (PDU) session;

[0180] • Based on the keepExistingPSA instruction, determine session continuity when using UL CL relocation; and

[0181] • Configure the target BP or UL CL and the target UPF.

[0182] Example 22. The SMF according to Example 21, wherein the SMF is also adapted to perform the method according to any one of Examples 19 and 20.

[0183] Example 23. A network node for implementing Session Management Function (SMF) for a core network of a cellular communication system, wherein the SMF is capable of coordinating seamless service continuity during Edge Application Server (EAS) relocation, the network node comprising:

[0184] • Network interface; and

[0185] • Processing circuitry associated with the network interface, adapted to enable the network node to implement SMF, such that the SMF is configured as follows:

[0186] ο Receive a setup request from the application function AF, which includes application setup information, including a keepExistingPSA indication, which indicates that session continuity should be maintained during uplink classifier UL CL relocation.

[0187] Based on the bootstrapping request, policy and charging control (PCC) rules are generated, including application bootstrapping information; and

[0188] Provide PCC rules to the Session Management Function (SMF).

[0189] Example 24. The network node according to Example 23, wherein the AF is also adapted to perform the method according to any one of Examples 19 and 20.

[0190] At least some of the following abbreviations may be used in this disclosure. In the event of inconsistencies between the abbreviations, the usage above shall prevail. If listed multiple times below, the first listing shall take precedence over the subsequent listings.

[0191] ·3GPP Third Generation Partnership Program

[0192] 5G (Fifth Generation)

[0193] ·5GC fifth-generation core

[0194] ·5GS Fifth Generation System

[0195] ·AF Application Functions

[0196] • AMF Access and Mobility Functions

[0197] ·AN access network

[0198] AP access point

[0199] Application-Specific Integrated Circuits (ASICs)

[0200] • AUSF Authentication Server Functionality

[0201] CPU (Central Processing Unit)

[0202] DN Data Network

[0203] DSP (Digital Signal Processor)

[0204] • eNB Enhanced or Evolved Node B

[0205] • EPS Evolutionary Grouping System

[0206] E-UTRA Evolved Universal Terrestrial Radio Access

[0207] FPGA (Field Programmable Gate Array)

[0208] gNB new radio base station

[0209] gNB-DU New Radio Base Station Distributed Unit HSS (Home Server)

[0210] IoT (Internet of Things)

[0211] IP Internet Protocol

[0212] LTE Long Term Evolution

[0213] MME Mobility Management Entity

[0214] MTC machine-type communication

[0215] • NEF Network Open Functionality

[0216] NF Network Functions

[0217] NR New Radio

[0218] • NRF Network Functions Storage Function

[0219] NSSF network slice selection function

[0220] • OTT over-the-top

[0221] PC (Personal Computer)

[0222] PCF policy control function

[0223] P-GW Packet Data Network Gateway

[0224] QoS (Quality of Service)

[0225] RAM (Random Access Memory)

[0226] RAN radio access network

[0227] ROM (Read-Only Memory)

[0228] ·RRH Remote Radio Header

[0229] RTT round trip time

[0230] • SCEF service capability opening function

[0231] SMF session management function

[0232] UDM Unified Data Management

[0233] UE (User Equipment)

[0234] UPF User-Face Functionality

[0235] Those skilled in the art will recognize improvements and modifications to the embodiments of this disclosure. All such improvements and modifications are considered to be within the scope of the concepts disclosed herein.

Claims

1. A method for coordinating seamless service continuity to an edge application server (EAS) during relocation in a cellular communication system (100), the method comprising: At the application function AF (212), a boot request including application boot information is sent (400) to the policy control function PCF (210), the application boot information including a keepExistingPSA indication indicating that a new path to the new data network access identifier DNAI and EAS is being established. The current user plane UP path to the current DNAI and to the EAS should be maintained; At the PCF: Receive the boot request (400) from the AF; Based on the bootstrapping request, a (402) Policy and Charging Control (PCC) rule is generated, wherein the PCC rule includes the application bootstrapping information containing the keepExistingPSA instruction; and Provide the PCC rule (402) to the Session Management Function (SMF) (208); and at the SMF: Receive the PCC rule from the PCF (402); Determine which PDU session anchor PSA to be changed from the source PSA to the target PSA for the Protocol Data Unit (PDU) session; Based on the keepExistingPSA instruction, it is determined that simultaneous connectivity should be provided on both the source PSA and the target PSA; and Configure the target PSA while maintaining the UP connection between the source PSA and the current DNAI and the EAS.

2. A method for coordinating seamless service continuity to an edge application server (EAS) during relocation in a cellular communication system (100), the method comprising: Application Function (AF) sends a (400) guidance request to Policy Control Function (PCF) (210) including application guidance information, which includes a keepExistingPSA indication that while establishing new paths to the new Data Network Access Identifier (DNAI) and Edge Application Server (EAS), the current User Plane UP path to the current DNAI and the current User Plane UP path to the EAS should be maintained.

3. The method according to claim 2, wherein, The application guidance information also includes a KeepExistingPSATimer indication, which indicates how long the previous Protocol Data Unit (PDU) session anchor PSA will be held.

4. The method according to claim 2, wherein, The application guidance information also includes an indication of the minimum time interval to be considered for inactivity of the source branch point BP / uplink classifier UL CL.

5. The method according to claim 2, wherein, The application guidance information also includes an indication of the minimum time interval to be considered for inactivity of the source user plane function UPF.

6. The method according to claim 2, further comprising: Determine whether to perform the EAS changes that require changes to the DNAI; as well as Invoke the Nnef_TrafficInfluence service, which includes the application boot information.

7. The method according to claim 2, further comprising: Determine whether to perform the EAS changes that require changes to the DNAI; as well as Send one of the Npcf_PolicyAuthorization create service request and the Npcf_PolicyAuthorization update service request, which include the application guidance information.

8. A network node (600) for implementing application function AF (212), wherein, The AF is capable of coordinating seamless service continuity to edge application server (EAS) relocation during relocation in the cellular communication system (100), and the network node is adapted to send (400) a guidance request to the policy control function (PCF) (210) including application guidance information, the application guidance information including a keepExistingPSA indication, the keepExistingPSA indication indicating that while establishing new paths to the new data network access identifier (DNAI) and edge application server (EAS), the current user plane UP path to the current DNAI and the current EAS should be maintained.

9. The network node according to claim 8, wherein, The network node is also adapted to perform the method according to any one of claims 3 to 7.

10. A method for coordinating seamless service continuity to an edge application server (EAS) during relocation, executed in a policy control function (PCF) (210) within the core network (110) of a cellular communication system (100), the method comprising: Receive (400) a boot request from application function AF (212) including application boot information, the application boot information including a keepExistingPSA indication, the keepExistingPSA indication indicating that while establishing new paths to the new data network access identifier DNAI and edge application server EAS, the current user plane UP path to the current DNAI and EAS should be maintained. Based on the aforementioned guidance request, a (402) policy and charging control (PCC) rule is generated, wherein, The PCC rule includes the application boot information; as well as Provide the PCC rule (402) to the session management function SMF (208).

11. The method of claim 10, wherein: The bootstrapping request targets a new Protocol Data Unit (PDU) session; as well as Generating the PCC rule includes generating the PCC rule during the establishment of the new PDU session.

12. The method according to claim 10, wherein: The bootstrapping request targets an ongoing Protocol Data Unit (PDU) session; as well as Generating the PCC rule includes generating the PCC rule during the modification of the ongoing PDU session.

13. A network node (600) for implementing policy control functions (PCF) (210) for a core network (110) of a cellular communication system (100), wherein, The PCF is capable of coordinating seamless service continuity with the Edge Application Server (EAS) during relocation, and the network node is suitable for: Receive (400) a boot request from application function AF (212) including application boot information, the application boot information including a keepExistingPSA indication, the keepExistingPSA indication indicating that while establishing new paths to the new data network access identifier DNAI and edge application server EAS, the current user plane UP path to the current DNAI and EAS should be maintained. Based on the aforementioned guidance request, a (402) policy and charging control (PCC) rule is generated, wherein, The PCC rule includes the application boot information; as well as Provide the PCC rule (402) to the session management function SMF (208).

14. The network node according to claim 13, wherein, The network node is also adapted to perform the method according to any one of claims 11 and 12.

15. A method for coordinating seamless service continuity to an edge application server (EAS) during relocation, performed in a session management function (SMF) (208) within the core network (110) of a cellular communication system (100), the method comprising: Receive (402) policy and charging control PCC rules from the policy control function PCF (210). The PCC rule includes application guidance information, which includes a keepExistingPSA instruction. The keepExistingPSA instruction indicates that while establishing new paths to the new Data Network Access Identifier (DNAI) and Edge Application Server (EAS), the current user plane UP path to the current DNAI and the current EAS should be maintained. Determine which PDU session anchor PSA to be changed from the source PSA to the target PSA for the Protocol Data Unit (PDU) session; Based on the keepExistingPSA instruction, it is determined that simultaneous connectivity should be provided on both the source PSA and the target PSA; and Configure the target PSA while maintaining connections to the current DNAI and the user plane UP of the EAS on the source PSA.

16. The method of claim 15, wherein: The application guidance information also includes a KeepExistingPSATimer indicator, which indicates how long the previous PSA will be maintained; and The method further includes: Based on the indication of how long to maintain the previous PSA, a timer of length one time interval is started; and Maintain source BP / UL CL and source UPF until the timer expires.

17. The method of claim 15, wherein: The application guidance information also includes an indication of the minimum time interval to be considered for inactivity of the source BP / UL CL and source UPF; as well as The method further includes: An inactive timer is started for services transmitted via the source BP / UL CL and the source UPF, wherein the inactive timer has a value equal to or greater than the minimum time interval; and After the inactivity period specified by the inactivity timer, the source BP / UL CL and the source UPF are removed.

18. A network node (600) for implementing a session management function (SMF) (208) for a core network (110) of a cellular communication system (100), wherein, The SMF enables seamless service continuity during edge application server (EAS) relocation, and the network node is suitable for: Receive (402) policy and charging control PCC rules from the policy control function PCF (210). The PCC rule includes application guidance information, which includes a keepExistingPSA instruction. The keepExistingPSA instruction indicates that while establishing new paths to the new Data Network Access Identifier (DNAI) and Edge Application Server (EAS), the current user plane UP path to the current DNAI and the current EAS should be maintained. Determine which PDU session anchor PSA to be changed from the source PSA to the target PSA for the Protocol Data Unit (PDU) session; Based on the keepExistingPSA instruction, it is determined that simultaneous connectivity should be provided on both the source PSA and the target PSA; and Configure the target PSA while maintaining connections to the current DNAI and the user plane UP of the EAS on the source PSA.

19. The network node according to claim 18, wherein, The network node is also adapted to perform the method according to any one of claims 16 and 17.

Images