WO2018205145A1

WO2018205145A1 - Method and apparatus for allocating registration area

Info

Publication number: WO2018205145A1
Application number: PCT/CN2017/083617
Authority: WO
Inventors: Xiaoyun Zhou; Jinguo Zhu; Minya Ye; Fangting ZHENG
Original assignee: Zte Corporation
Priority date: 2017-05-09
Filing date: 2017-05-09
Publication date: 2018-11-15

Abstract

A method for determining registration area information for a wireless communication node includes: receiving information about a first anchor function that is coupled to a data network; determining the registration area information for the wireless communication node based on the information about the first anchor function; and providing the registration area information to the wireless communication node.

Description

METHOD AND APPARATUS FOR ALLOCATING REGISTRATION AREA

TECHNICAL FIELD

This disclosure relates generally to wireless communications and, more particularly, to systems and methods for allocating a registration area to a user equipment device (UE) .

BACKGROUND

In general, when a UE, e.g., a cell phone, is switched on, the UE registers with a network to receive services from the network. Such a registration procedure is typically known as a Network Attachment procedure in the fourth generation (4G) Long Term Evolution (LTE) network. During or after the Network Attachment procedure, one or more tracking area lists (TAIs) , can be allocated (e.g., assigned) to the UE by a Mobile Management Entity (MME) of the legacy LTE network. An operator of a network may define a group of neighboring eNBs (or cells) as a tracking area (TA) , and a TAI may include a plurality of such TAs.

As used herein, the term "network" or "communication network" refers to infrastructure resources provided by a network operator to provide data communication services, which may include both wired and wireless services, to customers of the network operator. Examples of such network operators include AT&T, Verizon, Sprint, Vodafone, etc. Such a network may include a core portion, a radio access network (RAN) portion and backhaul portion, for example. The network may further comprise various virtualized resources and functions as would be understood by persons of ordinary skill in the art. As these networks adopt the next generation network standards (i.e., 5G) , referred to as “5G networks, ” they will become capable of providing various kinds of services in a single network based on a software-defined networking (SDN) concept.

Various virtualized resources and functions have been proposed to better implement the 5G network using the SDN concept. For example, the above-mentioned MME of the legacy LTE network has been split into Access and Mobility Management function (AMF) and Session Management Function (SMF) in the 5G network, which are configured to perform various access management functions (e.g., registration management) and session management functions (e.g., session establishment) , respectively, as will be discussed in further detail below.

SUMMARY OF THE INVENTION

The exemplary embodiments disclosed herein are directed to solving the issues relating to one or more of the problems presented in the prior art, as well as providing additional features that will become readily apparent by reference to the following detailed description when taken in conjunction with the accompany drawings. In accordance with various embodiments, exemplary systems, methods, devices and computer program products are disclosed herein. It is understood, however, that these embodiments are presented by way of example and not limitation, and it will be apparent to those of ordinary skill in the art who read the present disclosure that various modifications to the disclosed embodiments can be made while remaining within the scope of the invention.

In one embodiment, a method includes: receiving a registration request from a wireless communication node； determining registration area information for the wireless communication node based on mobility-related information associated with the wireless communication node, wherein the mobility-related information is provided by an access and mobility management function； and providing the registration area information to the wireless communication node.

In a further embodiment, a method includes: receiving information about a first anchor function that is coupled to a data network； determining registration area information for a wireless communication node based on the information about the first anchor function； and providing the registration area information to the wireless communication node.

In another embodiment, an apparatus includes: at least one processor and a memory coupled to the processor, the at least one processor configured to: receive a registration request from a wireless communication node； determine registration area information for the wireless communication node based on mobility-related information associated with the wireless communication node, wherein the mobility-related information is provided by an access and mobility management function； and provide the registration area information to the wireless communication node.

In yet another embodiment, an apparatus includes: at least one processor and a memory coupled to the at least one processor, the at least one processor configured to: receive information about a first anchor function that is coupled to a data network； determine registration area information for a wireless communication node based on the information about the first anchor function； and provide the registration area information to the wireless communication node.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary embodiments of the invention are described in detail below with reference to the following Figures. The drawings are provided for purposes of illustration only and merely depict exemplary embodiments of the invention to facilitate the reader's understanding of the invention. Therefore, the drawings presented herein should not be considered limiting of the breadth, scope, or applicability of the invention. It is also noted that for clarity and ease of illustration, the drawings are not necessarily drawn to scale.

Figure 1 illustrates a 5G communication system, in accordance with one embodiment of the present disclosure.

Figure 2 illustrates a method of determining a registration area for a UE when the UE performs an initial registration procedure in a network of the 5G communication system of Figure 1, in accordance with one embodiment of the present disclosure.

Figure 3 illustrates a method of determining a registration area for a UE when the UE requests to establish a PDU session in a network of the 5G communication system of Figure 1, in accordance with one embodiment of the present disclosure.

Figure 4 illustrates a method of determining a registration area for a UE when a previously established PDU session is released from a network of the 5G communication system of Figure 1, in accordance with one embodiment of the present disclosure.

Figure 5 illustrates a method of determining a registration area for a UE when a respective UPF of a previously established PDU session in a network of the 5G communication system of Figure 1 is determined to be relocated, in accordance with one embodiment of the present disclosure.

Figure 6 illustrates a method of determining a registration area for a UE when an additional UPF and a branching point (or an uplink classifier) are added to a previously established PDU session in a network of the 5G communication system of Figure 1, in accordance with one embodiment of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Various exemplary embodiments of the invention are described below with reference to the accompanying figures to enable a person of ordinary skill in the art to make and use the invention. As would be apparent to those of ordinary skill in the art, after reading the present disclosure, various changes or modifications to the examples described herein can be made without departing from the scope of the invention. Thus, the present invention is not limited to the exemplary embodiments and applications described and illustrated herein. Additionally, the specific order or hierarchy of steps in the methods disclosed herein are merely exemplary approaches. Based upon design preferences, the specific order or hierarchy of steps of the disclosed methods or processes can be re-arranged while remaining within the scope of the present invention. Thus, those of ordinary skill in the art will understand that the methods and techniques disclosed herein present various steps or acts in a sample order, and the invention is not limited to the specific order or hierarchy presented unless expressly stated otherwise.

As mentioned above, a UE registers with a network to receive service (s) , to enable mobility tracking, and to enable reachability. In the 5G network, the UE typically performs such a registration procedure to the 5G network, or a mobility registration update when the UE moves to a new registration area (also known as the “tracking area” in the LTE network) that is outside the UE’s previous registration area. The UE may also perform the registration procedure, when the UE performs a periodic registration update, and additionally when the UE update its capabilities and/or protocol parameters that are negotiated in the previous registration procedure.

In the currently being-developed 5G network, the above-mentioned AMF provides a new registration area to the UE, or updates an existing registration area of the UE, during the registration procedure. Particularly, the AMF solely relies on various previously defined or retrieved information of the UE to provide or update the registration area. This, however, may cause some issues in terms of accuracy of the registration area provided by the AMF. For example, such a UE’s previously defined or retrieved information may not be the most up-to-date, and may only include information such as which of various data networks the UE can access, but does not include information about a data network that the UE is currently accessing. In this regard, the present disclosure provides various embodiments of systems and methods to more accurately provide/update a registration area for the UE by taking into account not only the previously defined or retrieved information but also more up-to-date information corresponding to the UE, which will be discussed in further detail below.

Figure 1 illustrates an exemplary conventional architecture of a 5G communication system that spans at least one network 101 of UE 102. The network 101 may be a public land mobile network (PLMN) , for example. In some embodiments, the network 101 includes an Access and Mobility Management Function (AMF) 104, a 5G Radio Access Network (RAN) 106, a Session Management Function (SMF) 108, a User Plane Function (UPF) 110, a Policy Control Function (PCF) 112, and a Data Network 114.

The AMF 104 performs various access management functions that allow the UE 102 to access the 5G RAN 106. More specifically, the AMF 104 includes one or more of the following functionalities: registration management, connection management, reachability management and mobility management. This AMF 104 also performs access authentication and access authorization functions for the UE 102. The AMF 104 is also the non-access stratum (NAS) security termination and relays the session management (SM) NAS between the UE 102 and SMF 108, etc. Persons of ordinary skill in the art are familiar with the conventional functions of the AMF 104 and architecture of the 5G RAN 106.

The SMF 108 performs one or more of the following functions: session management (e.g., session establishment, modification and release) , UE IP address allocation &management (including optional authorization functions) , selection and control of user plane (UP) functions, downlink data notification, etc. The UPF 110 includes the following functionalities: serving as an anchor point for intra-/inter-radio access technology (RAT) mobility, packet routing &forwarding, traffic usage reporting, QoS handling for the user plane, downlink packet buffering and downlink data notification triggering, etc. Persons of ordinary skill in the art are familiar with the conventional functions of the SMF 108 and UPF 110.

The PCF 112 includes one or more of the following functionalities: supporting unified policy framework to govern network behavior, providing policy rules to the UPF 110 to enforce the policy rules, implementing a Front End to access subscription information relevant for policy decisions in a User Data Repository (UDR) , and in accordance with some embodiments of the present disclosure, determining or updating a registration area for the UE 102 based on various information. Various methods performed by the PCF 112 to determine or update a registration area for the UE 102 will be discussed below with respect to Figures 2, 3, 4, 5, and 6, respectively.

At least one Data Network 114 also resides within the network 101, which is a network providing service to the UE 102 such as, for example, the IMS network, Internet, etc. It is understood that Figure 1 does not include all of the infrastructure, components, resources and functions of a 5G network but, rather, only a subset of the infrastructure, components, resources and functions that are pertinent to the present disclosure.

As used herein, the term “function” refers to one or more virtual functions performed by one or more physical resources of a network, which are configured to perform the corresponding function. Such physical resources can include one or more processors, computers, servers, memories, databases, communication interfaces, etc. that may be co-located in a single network communication node or distributed among multiple nodes. Persons of ordinary skill in the art would be familiar with how the “functions” discussed herein can be implemented via hardware, firmware, software or any combination of these techniques.

As described below, the operations illustrated in Figures 2-6 may refer to functional entities, such as UE, AMF, SMF, UPF, etc. (either in physical or virtual form) , which are similar to those mentioned above with respect to conventional 5G communication systems. As would be understood by persons of ordinary skill in the art, however, such conventional functional entities do not perform the functions described below, and therefore, would need to be modified or specifically configured to perform one or more of the operations described below. Additionally, persons of skill in the art would be enabled to configure functional entities to perform the operations described herein after reading the present disclosure. The term “configured” as used herein with respect to a specified operation or function refers to a system, device, component, circuit, structure, machine, etc. that is physically or virtually constructed, programmed and/or arranged to perform the specified operation or function.

Figure 2 illustrates a method of determining a registration area for a UE 202 when the UE 202 performs an initial registration procedure in the network 101, in accordance with one embodiment. The term “initial registration procedure, ” as used herein refers to a UE performing a registration procedure with a network without establishing any Protocol Data Unit (PDU) session. As would be understood by persons of ordinary skill in the art, a PDU session refers to an association between a UE (e.g., 102) and a data network (e.g., 114) . At operation 1, the UE 202 sends a Registration Request message, which may be included in an Access Network (AN) message, to a 5G RAN 204 located in the network 101. In some embodiments, this registration request can include: registration type, a subscriber permanent identifier (SUPI) or a temporary User ID, security parameters, UE capability, PDU session status (if any) , and other information. Next, at operation 2, upon detecting the registration request from the UE 202, the 5G RAN 204 determines whether to choose a new AMF 206 or continue using a serving AMF (also referred to as “old AMF” ) 208. More specifically, in some embodiments, if at least one of the SUPI and temporary User ID indicates which of the AMF’s (206 and 208) to be used, the 5G RAN 204 chooses the indicted AMF (206 or 208) ； and if neither of the SUPI and temporary User ID indicates which of the AMF’s (206 and 208) to be used, the 5G RAN 204 will choose an AMF based on radio access technology (RAT) and network slice selection assistance information (NSSAI) , if available.

Next, at operation 3, the 5G RAN 204 sends a Registration Request message to the new AMF 206, wherein the message includes: N2 (achannel between the new AMF 206 and 5G RAN 204 in the network 101) parameters, and the registration request received from the UE 202. In some alternative embodiments, when the registration type, included in the registration request, indicates that such a registration request is a periodic registration update, steps 4 to 14, which will be discussed below, may be omitted. Next, at operation 4, the new AMF 206 sends an Information Request message to the old AMF 208. More specifically, in some embodiments, if the UE's Temporary User ID is included in the registration request and the serving AMF (e.g., the old AMF 208) has changed since last registration, the new AMF 206 may send the information request to the old AMF 208 to request the UE's SUPI and mobility management (MM) context from the old AMF 208. Next, at operation 5, the old AMF 208 sends an Information Response message to the new AMF 206, which includes the UE’s SUPI and MM Context, as requested, and SMF information associated with a previously PDU session. In some embodiments, the SMF information includes identity information of the previously PDU session and identity information of an SMF associated with the previously PDU session.

Next, at operation 6, the new AMF 206 sends an Identity Request message to the UE 202. In some embodiments, if the SUPI is not provided by the UE 202 nor retrieved from the old AMF 208, the new AMF 206 sends such an identity request to the UE 202. Next, at operation 7, the UE 202 sends an Identity Response message to the new AMF 206, which includes the UE 202’s SUPI. Next, at operation 8, the new AMF 206 may determine to perform an optional Authentication Server Function (AUSF) 212, which is illustrated as operation 9 including performing one or more authentication and NAS security procedures of the UE 202. Next, at operation 10, the new AMF 206 sends an Information Acknowledge message to the old AMF 208 for informing the old AMF 208 of successfully reception of the UE’s MM context.

Starting at operation 11, an update location procedure may be performed. In some embodiments, simultaneously with or subsequent to operation 11, the new AMF 206 may select a PCF 210 based on the UE’s SUPI. Next, at operation 12, the new AMF 206 sends a UE Context Establishment Request message to the PCF 210. In some embodiments, the new AMF 206 may include UE 202’s capability, and/or RAN 204’s capability in such a message. In particular, during operation 12, the new AMF 206 requests the PCF 210 to apply operator policies for the UE 202.

Next, at operation 13, the PCF 210 makes a policy decision by taking into account various mobility-related information about the UE 202, the UE’s capability, and the RAN’s capability, wherein, in accordance with some embodiments, the policy decision includes registration area information (e.g., a set of tracking areas in a TAI List) to be provided to the UE 202. In some embodiments, the mobility-related information includes: mobility pattern information about the UE 202, mobility restriction information about the UE 202, and local area data network (LADN) information about the UE 202. For example, in some embodiments, the mobility pattern information may include various behavioral information of the UE 202 (e.g., how the UE 202 moves on a regular (e.g., daily) basis, etc. ) ； the mobility restriction information may include allowed and non-allowed area (s) for the UE 202； and the LADN information may include which of a plurality of LADN’s the UE 202 can access at a current location. Further, such LADN information may be provided to the UE 202, which can include LADN Data Network Name (DNN) and LADN service area information of each of the respective LADN’s that UE 202 can access at the current location. The LADN service area information may be associated with a registration area.

Referring still to operation 13, the PCF 210 may also allocate a periodic registration update timer for the determined registration area. In some embodiments, the periodic registration update timer is configured to cause the UE 202 to update a respective registration area at a later time. In some other embodiments, if the PCF 210 doesn’ t have UE’s 202 subscription data, which may be further used to determine the registration area, the PCF 210 may contact a subscriber database 214 (typically referred to as “UDM) ” to retrieve the subscription data before the PCF 210 makes the policy decision (i.e., the registration area) . The subscription data may include the above-described motility pattern and mobility restriction.

Next, at operation 14, the PCF 210 sends a UE Context Establishment Acknowledge message to the new AMF 206, wherein the message includes the determined registration area. Next, at operation 15, the old AMF 208 may send a UE Context Termination Request message to the PCF 210. When the old AMF 208 previously requested UE context to be established in the PCF 210, the old AMD 208 may send such a request to terminate the UE context in the PCF. Next, at operation 16, the PCF 210 sends a UE Context Termination Acknowledge message to the old AMF 208 to acknowledge such a UE context termination request.

Next, at operation 17, the new AMF 206 sends a Registration Accept message to the UE 202, which includes a new Temporary User ID to indicate the AMF 206 itself, the registration area determined by the PCF 210, the mobility-related information about the UE 202, status of a PDU session (if any) , and the periodic registration update timer (if any) . If the PCF 210 does not provide the periodic registration update timer in operation 13, the new AMF 206 may provide one to the UE 202. Next, at operation 18, the UE 202 sends a Registration Complete message to the new AMF 206 to acknowledge a reception of the Temporary User ID (of the new AMF 206) .

It is noted that, with respect to the embodiment of Figure 2, the registration area allocated to the UE 202 is determined by the PCF 210 in such an initial registration procedure, which is different from a conventional 5G network that uses a respective AMF to determine a registration area for a UE. As would be understood by persons of ordinary skill in the art, one or more PDU sessions may be established/released in the network 101 after such an initial registration procedure. In this regard, using the PCF 210 to determine or update the registration area can provide various advantages (e.g., more accurately determining registration areas) especially when one of the above-mentioned scenarios occurs after the initial registration procedure in the network 101, which will be respectively discussed with respect to Figures 3-6 below.

Figure 3 illustrates a method of determining a registration area for the UE 202 when the UE 202 requests to establish a PDU session in the network 101, in accordance with one embodiment. In some embodiments, the method of Figure 3 may be performed after the UE 202 has performed the initial registration procedure as described in Figure 2.

At operation 1, the UE 202 sends a PDU Session Establishment Request message, which can be a NAS message, for example, to the new AMF 206. In some embodiments, the NAS message may include a data network name (DNN) , a PDU session ID, request type (e.g., an initial request) , N1 (achannel between the UE 202 and the new AMF 206 in the network 101) session management (SM) information. Next, at operation 2, the new AMF 206 determines that the NAS message corresponds to a request for establishing a new PDU session when the request type, included on the NAA message, indicates an initial request, and when the PDU Session ID is not used for any existing PDU session (s) of the UE 202. Based on the information included in the NAS message, the new AMF 206 selects an SMF 216 and stores an association between the PDU session ID and an SMF ID the belongs to the selected SMF 218.

Next, at operation 3, the new AMF 206 sends an SM Request (with PDU Session Establishment Request) message to the SMF 218. The SM Request message includes Subscriber Permanent ID (of the UE 202) , the DNN, the PDU Session ID, an AMF ID associated with the new AMF 206, N1 SM information, user location information, access technology type, etc. Next, at operation 4, the SMF 218 may send a Subscription data Request message to the UDM 214 if the SMF 218 has not yet retrieved SM-related subscription data for the UE 202, which is also related with the DNN. The subscription data request includes the Subscriber Permanent ID of the UE 202 and the DNN. Next, at operation 5, the UDM 214 sends a Subscription data Response message to the SMF 218, wherein the subscription data response includes authorized PDU type (s) , authorized SCC mode (s) , default QoS profile, etc.

Next, at operation 6, the SMF 218 selects a UPF (e.g., 216) and allocates an IP address for the PDU session. Moreover, the SMF 218 sends a PDU-Connectivity Access Network (CAN) Establishment Request message to the PCF 210 to obtain one or more default policy rules for the PDU Session. In some embodiments, the SMF 218 includes the SUPI, the IP address, the DNN, and various information about the selected UPF (e.g. identity information of the selected UPF, location information of the selected UPF, etc. ) in the PDU-CAN session establishment request. Simultaneously with or subsequently to the operation 6, the PCF 210 makes a policy decision based on the various information received, e.g., the DNN, the location of the selected UPF, etc., and sends one or more determined policies back to the SMF 218 via a PDU-CAN Establishment Acknowledge message, which corresponds to operation 7.

Next, at operation 8, the SMF 218 sends an N4 (achannel between the SMF 218 and the UPF 216 in the network 101) Session Establishment Request message to the selected UPF 216 and provides packet detection, enforcement and reporting rules to be installed on the UPF 216 for this PDU Session. If Core Network (CN) tunnel information is allocated by the SMF 218, the CN tunnel information is provided to UPF 216 in this operation. As understood by persons of ordinary skill in the art, such CN tunnel information is typically used to establish a tunnel (e.g., an association) between the UPF 216 and the 5G RAN 204. Then, at operation 9, the UPF 216 acknowledges the N4 session establishment request by sending an N4 Session Establishment Response message. If the CN Tunnel information is allocated by the UPF 216 (instead of the SMF 218 as mentioned above) , the CN tunnel information is provided to the SMF 218 in this operation.

Next, at operation 10, the SMF 218 sends a SM Request acknowledgement (Ack) message to the new AMF 206 including Cause (e.g. a result code) , N2 SM information (e.g., PDU Session ID, QoS Profile (s) , CN tunnel information) , N1 SM information (e.g., PDU session establishment accept information (e.g., Authorized QoS rule, SSC mode, allocated IPv4 address) ) , etc. Next, at operation 11, the new AMF 206 sends an N2 PDU Session Request message to the 5G RAN 204 including the N2 SM information, and the NAS message (e.g., the PDU Session ID, the PDU session establishment accept) . Next, at operation 12, the 5G RAN 204 may issue an Access Network (AN) -specific resource setup message that exchanges between the UE 202 and 5G RAN 204 based on the information received from the SMF 218. Next, at operation 13, the 5G RAN 204 sends an N2 PDU Session Request Ack message to the new AMF 206, which includes the PDU Session ID, the Cause, the N2 SM information (PDU Session ID, (R)AN tunnel information, a list of accepted/rejected QoS profile (s)) .

Next, at operation 14, the new AMF 206 send an SM Request message to the SMF 218, which includes the N2 SM information. Next, at operation 15, the SMF 218 initiates an N4 Session modification procedure with the UPF 216 by sending an N4 Session Modification Request message. The SMF 218 provides the (R) AN tunnel information and CN tunnel information. In some embodiments, the CN tunnel information only needs to be provided when it is the SMF 218 selecting the CN tunnel information (i.e., operation 8) . Next, at operation 16, the UPF 216 provides an N4 Session Modification Response message to the SMF 218. At operation 17, the SMF 218 sends an SM Request Ack message to the new AMF 206. Next, at optional operation 18, when the PDU session is a PDU Type IPv6, for example, the SMF 218 generates an IPv6 router advertisement and sends it to the UE 202 via the UPF 216.

Next, at operation 19, the PCF 210 may send a Mobility Policy Update Request message to the new AMF 206 to provide a newly determined registration area (e.g., an updated registration area) to the new AMF 206, in accordance with some embodiments. More specifically, the PCF 210 may determine the updated registration area based on the DNN (specified by the UE 202 at operation 1) , the information of the selected UPF 216 (e.g. identity information of the UPF 216, location information of the UPF 216, etc. ) , and/or the above-mentioned mobility-related information of the UE 202. Similarly, the mobility policy update request, sent by the PCF 210, may further include a periodic registration update timer.

Next, at operation 20, the new AMF 206 uses a NAS massage, exchanged between the new AMF 206 and the UE 202, to let the UE 202 know the updated registration area and the periodic registration update timer. In some other embodiments, if the PCF 210 does not provide the periodic registration update timer in operation 19, the new AMF 206 selects one and provides it to the UE 202. Next, at operation 21, the new AMF 206 sends a Mobility Policy Update Response message to the PCF 210.

In the exemplary embodiment of Figure 3, in addition to using the mobility-related information of the UE 202, the PCF 210 further uses the DNN (specified by the UE 202 at operation 1) and the information of the selected UPF 216 (e.g. identity information of the UPF 216, location information of the UPF 216, etc. ) to determine (or update) a registration area. As such, the determined registration area may be more accurate because, for example, the DNN can indicate a local data network that the UE 202 is currently accessing, etc. In further embodiments, when the UE 202 initiates additional PDU session (s) , similar operations can be performed. In such further embodiments, the PCF 210 may take additional data network (s) and/or UPF (s) into account to accurately determine an updated registration area.

Figure 4 illustrates a method of determining a registration area for the UE 202 when a previously established PDU session is released from the network 101, in accordance with one embodiment. Such a PDU Session Release procedure may be triggered by at least one of three options, which are respectively discussed as operations 1a, 1b, and 1c below. At operation 1a, the UE 202 initiates a UE requested PDU session release procedure by sending an N11 (achannel between the new AMF 206 and the SMF 218 in the network 101) message with a PDU session release request, including a respective PDU Session ID, to the new AMF 206. This request is then relayed to an SMF (e.g., 218) corresponding to the PDU Session ID. At operation 1b, the PCF 210 may initiate a PDU-CAN Session Modification procedure to request the release of the established PDU session. At operation 1c, the SMF 218 may decide to release a PDU session based on a request from the data network 114 (e.g., cancelling the UE 202’s authorization to access the data network) , or a request from the UDM 214 (e.g., subscription change) or from an online charging system (OCS) . The release procedure may also be triggered by a locally configured policy (e.g., the release procedure may be related with a UPF relocation for session and service continuity (SSC) mode 2 /mode 3) . As such, when the SMF 218 receives one of the triggers described in operations 1a-1c, the SMF 218 starts the PDU session release procedure.

Next, at operation 2, in response to at least one of the triggers, the SMF 218 initiates a PDU-CAN session termination procedure by sending a PDU-CAN Session Termination Request message to the PCF 210. Next, at operation 3, the PCF 210 removes context of the PDU-CAN session and sends a PDU-CAN Termination Acknowledge message to the SMF 218. Next, at operation 4, the SMF 218 releases IP address/Prefix (es) that were allocated to the PDU session and releases corresponding User Plane resources. The SMF then sends an N4 Session Release Request message, including an N4 Session ID, to the UPF 216. In response to the request, the UPF 216 drops remaining packets of the PDU session and releases all tunnel resource and contexts associated with the N4 session. Next, at operation 5, the UPF 216 acknowledges the N4 session release request by sending an N4 Session Release Response message, including the N4 Session ID, to the SMF 218.

Next, at operation 6, the SMF 218 sends an N11 Request message to the new AMF 206, which includes N2 SM resource release request, and N1 SM information (e.g., PDU session release command) ) . Next, at operation 7, the new AMF 206 sends an N2 Resource Release message to the 5G RAN 204. Next, at operation 8, when the 5G RAN 204 has received the N2 SM request to release AN resources associated with the PDU session, the 5G RAN 204 performs AN-specific signaling exchange with the UE 202 to release corresponding AN resources. Next, at operation 9, if the 5G RAN 204 has received the N2 SM request to release the AN resources, the 5G RAN 204 acknowledges the N2 SM resource release request by sending an N2 SM Resource Release Ack message, including the N1 SM information, to the new AMF 206. Otherwise, the 5G RAN 204 forwards the N1 SM information from the UE 202 to the new AMF 206. Next, at operation 10, the new AMF 206 sends an N11 Response message, including the N1 SM Information (PDU Session Release Ack) , to the SMF 218. Next, at operation 11, the SMF 218 notifies the new AMF 206 that the PDU session is released by sending an N11 message. In response, the new AMF 206 and SMF 218 remove all contexts (including the PDU session ID) associated with the PDU session.

Next, at operation 12, in accordance with some embodiments, the PCF 210 may update a registration area without considering the DNN and/or the information of the selected UPF (e.g. Identity of the UPF, Location of the UPF, etc. ) of the released PDU session. The PCF 210 sends a Mobility Policy Update Request message to the new AMF 206 indicating such an updated registration area. Similarly, the PCF 210 may also determine a periodic registration update timer and provide it to the new AMF 206. Next, at operation 13, the new AMF 206 sends a NAS message to the UE 202 including the updated registration area and the periodic registration update timer. If the PCF 210 does not provide the periodic registration update timer in operation 12, the new AMF 206 decides one and provides it to the UE 202. The UE 202 acknowledges a reception of the updated registration area and the periodic registration update timer (if any) using the NAS message. Next, at operation 14, the new AMF 206 sends a Mobility Policy Update Response message to the PCF 210.

As mentioned above, the UPF 216 serves as an anchor function in a respective PDU session that is configured to couple (e.g., connect) the UE 202 to the data network 114 (Figure 1) . In this embodiment (Figure 4) , when the previously established PDU session is determined to be released from the network 101, one or more of the corresponding UPF’s (e.g., 216) are each asked to drop remaining packets of that PDU session and other resources as mentioned above (e.g., the UPF’s are changed) . Accordingly, it can be understood that, in some embodiments, when an UPF is changed, due to a release of a corresponding PDU session, for example, the PCF 210 may determine to update the registration area. Figures 5 and 6, as will be discussed below, respectively illustrate two scenarios when one or more UPF’s in the network 101 are changed, and a respective registration area is updated.

Figure 5 illustrates a method of determining a registration area for the UE 202 when a respective UPF of a previously established PDU session in the network 101 is determined to be relocated (e.g., replaced by a new UPF) , in accordance with one embodiment. In this particular embodiment, at least one PDU session may have been established in the network 101, and the UE 202 may use a respective UPF, selected by the PDU session, to connect to the data network 114, which can be seen at operation 1. More specifically, at operation 1, the UE 202 has established a PDU session using UPF1 220 as a respective PDU session anchor. Next, at operation 2, the SMF 210 determines that the (serving) UPF1 220 needs to be relocated (e.g., replaced) .

Next, at operation 3, the SMF 210 sends a NAS message to the UE 202 via the new AMF 206 to notify that the PDU session will be released at a later time, and to offer that a new PDU session can be associated to the same data network 114. In some embodiments, the NAS message includes the PDU session ID (of the to-be released PDU session) and a timer value indicative of how long the network 101 is going to keep the to-be released PDU session.

Next, at operation 4, in some embodiments, the UE 202 initiates a PDU session establishment procedure with a new PDU Session ID and an old PDU session ID corresponding to the new PDU session and the to-be released PDU session, respectively. As mentioned above, the new PDU session may be allowed to couple the UE 202 to the same data network 114. The new AMF 206 uses the same SMF 218 according to the old PDU session ID. The new AMF 206 sends the old PDU session ID, together with N1 SM information, to the SMF 210 through a N11 message. The SMF 218 then detects whether a corresponding PDU session establishment request (to initiate the PDU session establishment procedure) is related to the trigger in operation 3 (e.g., the SMF 210 sends a NAS message to the UE 202 via the new AMF 206 to notify that the PDU session will be released at a later time, and to offer that a new PDU session can be associated to the same data network 114) based on the old PDU session ID received from the new AMF 206, and a presence of the new PDU session ID in the N1 SM information. The SMF 218 stores the new PDU session ID and selects a new PDU session anchor (e.g., UPF2 224) for the new PDU session. The SMF 218 provides the new PDU session ID to the new AMF 206. The new AMF 206 stores an association of the new PDU session ID and a corresponding SMF ID of the SMF 218 for the new PDU session.

Next, at operation 5, the SMF 218 sends a PDU-CAN Session Modification Request message to the PCF 210, which includes a new IP address and new information of the UPF2 224. Next, at operation 6, the PCF 210 determines a policy and responds the SMF 218 with the determined policy by sending a PDU-CAN Modification Acknowledge message. Next, at operation 7, the old PDU session is released either by the UE 202 (e.g., once the UE has consolidated all traffic on the new PDU session) or by the SMF 218 upon expiry of the timer provided in operation 1.

Next, at operation 8, the PCF 210 may send a Mobility Policy Update Request message to the new AMF 206, wherein the message may include an updated registration area for the UE 202 that is determined based on a DNN of the data network 114 and/or information of UPF2 224 (e.g. identity information of the UPF2 224, location information of the UPF2 224, etc. ) . In other words, in addition to the mobility-related information, the PCF 210 determines the registration area based on the DNN and/or the information of one or more of the UPF’s (e.g., 224) of all active PDU sessions. The PCF 210 may also determine a periodic registration update timer and provide it to the new AMF 206.

Next, at operation 9, the new AMF 206 sends a NAS massage to the UE 202 including the updated registration area and the periodic registration update timer. If the PCF 210 does not provide the periodic registration update timer in operation 8, the new AMF 206 decides one and provide it to the UE 202. The UE 202 acknowledges a reception of the updated registration area and the periodic registration update timer (if any) using the NAS message. Next, at operation 10, the new AMF 206 sends a Mobility Policy Update Response message to the PCF 210 to acknowledge the update of the registration area.

Figure 6 illustrates a method of determining a registration area for the UE 202 when an additional UPF and a branching point (or an uplink classifier) are added to a previously established PDU session in the network 101, in accordance with one embodiment. In this particular embodiment, at least one PDU session may have been established in the network 101, and the UE 202 may use a respective UPF, selected by the PDU session, to connect to the data network 114, which is shown as operation 1 in Figure 6. More specifically, at operation 1, the UE 202 has established a PDU session using UPF1 226 as a respective PDU session anchor. Next, at operation 2, the SMF 218 decides to establish a new PDU session anchor (e.g., UPF2 228) due to the UE 202’s mobility, new flow detection (aflow corresponding to a new service that the UE 202 has accessed) , etc. In some cases, when the established PDU session is an IPv6 multi-homing PDU session (aPDU session including multiple IPv6 prefixes) , the SMF 218 also allocates a new IPv6 prefix to UPF2 228.

Next, at operation 3, the SMF 218 establishes a branching point (BP) (in case of IPv6 multi-homing) or an uplink classifier (UL CL) , hereinafter BP/UL CL 230, for the established PDU Session. In some embodiments, the BP/UL CL 230 provides necessary uplink forwarding rules to the UPF1 226 and UPF2 228, which may include CN tunnel information for the UPF1 226 and CN tunnel information for the UPF2 228. In addition, AN tunnel information is provided for downlink forwarding. In the example where the PDU session is IPv6 multi-homing PDU session, the SMF 218 also provides traffic filters for IPv6 prefixes to UPF1 226 and UPF2 228 to indicate what traffic can be forwarded to the UPF1 226 and UPF2 228, respectively. In the case where a UL CL is established, the SMF 218 provides traffic filters to indicate what traffic can be forwarded to the UPF1 226 and UPF2 228, respectively.

Next, at operation 4, the SMF 218 updates the UPF1 226 for downlink traffic. More specifically, the SMF 218 provides CN tunnel information of the BP or UL CL 230 to be used by UPF1’s 226 downlink traffic. Next, at operation 5, the SMF 218 updates UPF2 228 by providing the CN tunnel information of the BP or UL CL 230 to be used by UPF2’s 228 downlink traffic. Next, at operation 6, the SMF 218 updates the 5G RAN 204 by providing the CN tunnel information corresponding to Branching Point or UL CL 230. In case of UL CL, if there is an existing UPF between the (R) AN and new inserted UL CL, the SMF updates the existing UPF via N4 instead of updating the (R) AN.

Next, at operation 7, in the example of the IPv6 multi-homing PDU session, the SMF 218 notifies the UE 202 of availability of a new IP prefix via the UPF2 228, which may be performed using a first IPv6 router advertisement message. Also, the SMF 218 sends routing rule along with the IPv6 prefix to the UE 202. Next, at operation 8, in the example of the IPv6 multi-homing PDU session, the SMF 218 may re-configure the UE 202 for an original IP prefix via the UPF1 226, which may be performed using a second IPv6 router advertisement message.

Next, at operation 9, the SMF 218 sends a PDU-CAN Modification Request message to the PCF 210 including a new IP address and other new information (e.g., Identity of the UPF2 228, Location of the UPF2 228, etc. ) . Next, at operation 10, the PCF 210 determines a policy and responds the SMF 218 with the determined policy via a PDU-CAN Modification Acknowledge message. Next, at operation 11, the PCF 210 may send a Mobility Policy Update Request message to the new AMF 206, wherein the mobility policy update request may include an updated registration area for the UE 202 that is determined based on a DNN of the data network 114 and/or information of UPF2 224 (e.g. identity information of the UPF2 224, location information of the UPF2 224, etc. ) . In other words, in addition to the mobility-related information, the PCF 210 determines the registration area based on the DNN and/or the information of one or more of the UPF’s (e.g., 226 and 228) of all active PDU sessions. The PCF 210 may also determine a periodic registration update timer and provide it to the AMF 206. Next, at operation 12, the new AMF 206 sends a NAS massage to the UE 202 including the updated registration area and the periodic registration update timer. If the PCF 210 does not provide the periodic registration update timer in operation 8, the new AMF 206 selects one and provides it to the UE 202. The UE 202 acknowledges a reception of the updated registration area and the periodic registration update timer (if any) using the NAS message. Next, at operation 13, the new AMF 206 sends a Mobility Policy Update Response message to the PCF 210 to acknowledge the update of the registration area.

While various embodiments of the invention have been described above, they have been presented by way of example only, and not by way of limitation. Likewise, the various diagrams may depict an example architectural or configuration, which are provided to enable persons of ordinary skill in the art to understand exemplary features and functions of the invention. Such persons would understand, however, that the invention is not restricted to the illustrated example architectures or configurations, but can be implemented using a variety of alternative architectures and configurations. Additionally, as would be understood by persons of ordinary skill in the art, one or more features of one embodiment can be combined with one or more features of another embodiment described herein. Thus, the breadth and scope of the present disclosure is not limited to the above-described exemplary embodiments.

Additionally, any reference to an element herein using a designation such as "first, " "second, " and so forth does not generally limit the quantity or order of those elements. Rather, these designations are used herein as a convenient means of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements can be present, or that the first element must precede the second element in some manner.

Additionally, a person having ordinary skill in the art would understand that information and signals can be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits and symbols, for example, which may be referenced in the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

A person of ordinary skill in the art would further appreciate that any of the various illustrative logical blocks, modules, processors, means, circuits, methods and functions described in connection with the aspects disclosed herein can be implemented by electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of the two) , firmware, software, or any combination of these techniques. To illustrate this interchangeability of hardware, firmware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware or software, or a combination of these technique, depends upon the particular application and design constraints imposed on the overall system. Skilled artisans can implement the described functionality in various ways for each particular application, but such implementation would not cause a departure from the scope of the present disclosure.

Furthermore, a person of ordinary skill in the art would understand that various illustrative logical blocks, modules, devices, components and circuits described herein can be implemented within or performed by an integrated circuit (IC) that can include a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) , or other programmable logic device, or any combination of these implementations. The logical blocks, modules, and circuits can further include antennas and/or transceivers to communicate with various components within the network or within the device. A general purpose processor can be a microprocessor, but in the alternative, the processor can be any conventional processor, controller, or state machine. A processor can also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other suitable configuration to perform the functions described herein.

If implemented in software, the functions can be stored as one or more instructions or code on a computer-readable medium. Thus, the steps of a method or algorithm disclosed herein can be implemented by executing software stored on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that can transfer a computer program or code from one place to another. A storage media can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can store desired program code in the form of instructions or data structures and that can be accessed by a computer.

In this document, the terms "module" or “unit” as used herein, refer to software, firmware, hardware, and any combination of these elements for performing the associated functions described herein. Additionally, for purpose of discussion, the various modules or units are described as discrete modules or units； however, as would be apparent to one of ordinary skill in the art, two or more modules or units may be combined to form a single module or unit that performs the associated functions according embodiments of the invention.

Additionally, memory or other storage, as well as communication components, may be employed in embodiments of the invention. It will be appreciated that, for clarity purposes, the above description has described embodiments of the invention with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionality between different functional units, processing logic elements or domains may be used without detracting from the invention. For example, functionality illustrated to be performed by separate processing logic elements, or controllers, may be performed by the same processing logic element, or controller. Hence, references to specific functional units are only references to a suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organization.

Various modifications to the implementations described in this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other implementations without departing from the scope of this disclosure. Thus, the disclosure is not intended to be limited to the implementations shown herein, but is to be accorded the widest scope consistent with the novel features and principles disclosed herein, as recited in the claims below.

Claims

A method, comprising:

receiving a registration request from a wireless communication node；

determining registration area information for the wireless communication node based on mobility-related information associated with the wireless communication node, wherein the mobility-related information is provided by an access and mobility management function； and

providing the registration area information to the wireless communication node.
The method of claim 1, wherein the mobility-related information comprises at least one of: a mobility pattern of the wireless communication node, mobility restriction information of the wireless communication node, and local area network information of the wireless communication node.
The method of claim 1, wherein the providing the registration area information to the wireless communication node comprises:

providing the registration area information to the wireless communication node through the access and mobility management function.
The method of claim 1, wherein the providing the registration area information to the wireless communication node comprises:

providing a registration timer to the wireless communication node, wherein the registration timer is configured to cause the wireless communication node to update the registration area at a later time.
A method, comprising:

receiving information about a first anchor function that is coupled to a data network；

determining registration area information for a wireless communication node based on the information about the first anchor function； and

providing the registration area information to the wireless communication node.
The method of claim 5, wherein the information about the first anchor function comprises at least one of: identity information of the first anchor function, and location information of the first anchor function.
The method of claim 5, wherein the determining registration area information for a wireless communication node is further based on identity information of the data network, a mobility pattern of the wireless communication node, mobility restriction information of the wireless communication node, and/or local area network information of the wireless communication node.
The method of claim 7, wherein the first anchor function is associated with a first protocol data unit session configured to connect the wireless communication node to the data network.
The method of claim 8, further comprising:

selectively determining whether to update the registration area information for the wireless communication node in accordance with whether at least one of the data network to which the first protocol data unit session is configured to connect and the first anchor function is changed.
The method of claim 9, further comprising:

when the first anchor function is replaced by a second anchor function, determining updated registration area information for the wireless communication node based on information about the second anchor function； and

providing the updated registration area information to the wireless communication node.
The method of claim 10, wherein the second anchor function is associated with a second protocol data unit session configured to connect the wireless communication node to the same or a different data network.
The method of claim 9, further comprising:

when the first anchor function is changed under a release of the first protocol data unit session, determining updated registration area information for the wireless communication node without considering the information about the first anchor function and the identity information of the data network； and

providing the updated registration area information to the wireless communication node.
The method of claim 9, further comprising:

receiving information about a third anchor function, wherein the first and third anchor functions are associated with the first protocol data unit session, and wherein the first and third anchor functions are coupled to a common branch point or uplink classifier associated with the first protocol data unit session.
The method of claim 13, further comprising:

determining updated registration area information for the wireless communication node based on the information about the third anchor function； and

providing the updated registration area information to the wireless communication node.
An apparatus, comprising:

at least one processor and a memory coupled to the processor, the at least one processor configured to:

receive a registration request from a wireless communication node；

determine registration area information for the wireless communication node based on mobility-related information associated with the wireless communication node, wherein the mobility-related information is provided by an access and mobility management function； and

provide the registration area information to the wireless communication node.
The apparatus of claim 15, wherein the mobility-related information comprises at least one of: a mobility pattern of the wireless communication node, mobility restriction information of the wireless communication node, and local area network information of the wireless communication node.
The apparatus of claim 15, wherein the at least one processor is further configured to:

provide the registration area information to the wireless communication node through the access and mobility management function.
The apparatus of claim 15, wherein the at least one processor is further configured to:

provide a registration timer to the wireless communication node, wherein the registration timer is configured to cause the wireless communication node to update the registration area at a later time.
An apparatus, comprising:

at least one processor and a memory coupled to the processor, the at least one processor configured to:

receive information about a first anchor function that is coupled to a data network；

determine registration area information for a wireless communication node based on the information about the first anchor function； and

provide the registration area information to the wireless communication node.
The apparatus of claim 19, wherein the information about the first anchor function comprises at least one of: identity information of the first anchor function, and location information of the first anchor function.
The apparatus of claim 20, wherein the at least one processor is further configured to:

determine the registration area information for the wireless communication node further based on identity information of the data network, a mobility pattern of the wireless communication node, mobility restriction information of the wireless communication node, and/or local area network information of the wireless communication node.
The apparatus of claim 21, wherein the first anchor function is associated with a first protocol data unit session configured to connect the wireless communication node to the data network.
The apparatus of claim 22, wherein the at least one processor is further configured to:

selectively determine whether to update the registration area information for the wireless communication node in accordance with whether at least one of the data network to which the first protocol data unit session is configured to connect and the first anchor function is changed.
The apparatus of claim 23, wherein the at least one processor is further configured to:

when the first anchor function is replaced by a second anchor function, determine updated registration area information for the wireless communication node based on information about the second anchor function； and

provide the updated registration area information to the wireless communication node.
The apparatus of claim 24, wherein the second anchor function is associated with a second protocol data unit session configured to connect the wireless communication node to the same or a different data network.
The apparatus of claim 23, wherein the at least one processor is further configured to:

when the first anchor function is changed under a release of the first protocol data unit session, determine updated registration area information for the wireless communication node without considering the information about the first anchor function and the identity information of the data network； and

provide the updated registration area information to the wireless communication node.
The apparatus of claim 23, wherein the at least one processor is further configured to:

receive information about a third anchor function, wherein the first and third anchor functions are associated with the first protocol data unit session, and wherein the first and third anchor functions are coupled to a common branch point or uplink classifier associated with the first protocol data unit session.
The apparatus of claim 27, wherein the at least one processor is further configured to:

determine updated registration area information for the wireless communication node based on the information about the third anchor function； and

provide the updated registration area information to the wireless communication node.