Patent Publication Number: US-11647082-B2

Title: System and method for managing central unit-user plane locations

Description:
BACKGROUND INFORMATION 
     In contrast to other types of radio networks, advanced wireless radio networks, such as Fifth Generation (5G) radio access networks (NG-RAN), allow the function of a wireless station in the NG-RAN to be split into its constituent functional components: a Central Unit-Control Plane (CU-CP), a Central Unit User Plane (CU-UP), Distributed Units (DUs), and/or Radio Units (RUs). Such a split is aimed to increase flexibility in network design and to allow scalable and cost-effective network deployments. By splitting the functions of a wireless station, it is possible to tune particular performance parameters that depend on applications (e.g., gaming application, Voice-over-IP (VoIP) application, video streaming application, etc.) with different latency requirements. The performance parameters may be tuned based on the locations of the devices receiving the service, and/or on other variables. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1 A- 1 C  illustrate concepts described herein; 
         FIG.  2    illustrates an exemplary network environment in which the systems and methods described herein may be implemented; 
         FIG.  3    illustrates exemplary functional components of a core network, according to an implementation; 
         FIG.  4    illustrates an exemplary functional components of a wireless station, according to an implementation; 
         FIG.  5 A  illustrates an exemplary network layout of Integrated Access and Backhaul (IAB) nodes according to an implementation; 
         FIG.  5 B  illustrates exemplary functional components of IAB nodes and an IAB donor according to an implementation; 
         FIG.  6    illustrates exemplary functional components of the system, according to an implementation; 
         FIG.  7 A  shows exemplary fields of an Internet Protocol version 6 (IPv6) address, according to an implementation; 
         FIG.  7 B  illustrate a Protocol Data Unit (PDU) related message and Information Elements in the message; 
         FIG.  8    is a processing diagram that is associated with modifying a traffic path between a User Equipment device (UE) and an endpoint; 
         FIG.  9    depicts signaling and data paths between different network components for the system during the process of  FIG.  8   ; 
         FIG.  10    is a processing diagram that is associated with modifying a traffic path between a UE and an endpoint when the UE moves from one location to another location; 
         FIG.  11    depicts signaling and data paths between different network components for the system during the process of  FIG.  10   ; and 
         FIG.  12    depicts exemplary components of an exemplary network device, according to an implementation. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. 
     The systems and methods described herein relate to changing a path for network traffic, by selecting network nodes based on their geographical locations and inserting the selected nodes in the path to divert the traffic. In Fifth Generation (5G) networks, certain network components, such as an Application Function (AF), a Session Management Function (SMF), and/or a Policy Control Function (PCF), may steer traffic. Steering may be for network optimizations and to provide the optimum paths for user plane traffic, for meeting Service Level Agreement (SLA) requirements, etc. For example, in response to a message from a PCF, an SMF may insert a node in a data path, such as an uplink classifier (UL CL) node. The UL CL node may direct or steer traffic whose characteristics match filtering criteria specified by the SMF to a different data path. 
     The systems and methods described herein permit network functions to change traffic paths/routes, by selecting network nodes based on their geographical locations and inserting the selected nodes in the paths. By selecting and inserting the nodes based on their locations, the system may decrease latency associated with routes.  FIGS.  1 A  though  1 C illustrate the concepts described herein. As shown in  FIG.  1 A , a User Equipment device (UE)  102  establishes a session with an endpoint (not shown) over a DU  406 , a CU-UP  404 - 1 , and UPF  306 - 1 . Each of DU  406 , CU-UP  404 - 1 , and UPF  306  is described below with reference to  FIGS.  3  and  4   . It is noted that although the link between UE  102  and DU  406  is established through a Radio Unit (RU) or other network elements, such network elements are not shown for simplicity. As depicted, the path includes a route segment  104 , which carries traffic between DU  406  and CU-UP  404 - 1 . 
       FIG.  1 B  illustrates diverting traffic away from UPF  306 - 1  to a different UPF  306 - 2 . UPF  306 - 2  may be implemented as, for example, a UL CL node. As noted above, the system described herein may select a UPF  306 - 2  based on its physical location, so that UPF  306 - 2  can forward data from DU  406  to an endpoint for processing. However, if the system were to simply reconfigure CU-UP  404 - 1  so that it forwards the data, which CU-UP  404 - 1  receives from DU  406 , to UPF  306 - 2  as shown in  FIG.  1 B , the new path  106  may introduce delays in conveying the data if CU-UP  404 - 1  is physically far from UPF  306 - 2 . Accordingly, rather than just selecting UPF  306 - 2  and configuring CP-UP  404 - 1  to deliver data from UE  102  to an endpoint through UPF  306 - 2 , the system also selects a CU-UP  404 - 2  ( FIG.  1 C ) based on its location and configures the selected CU-UP  404 - 2 , such that if CU-UP  404 - 2  receives data from UE  102  through DU  406 , CU-UP  404 - 2  would forward the data to UPF  306 - 2 . Furthermore, the system configures DU  406  so that DU  406  forwards the data from UE  102  to CU-UP  404 - 2 , rather than to CU-UP  404 - 1 . 
     The result of the selections of UPF  306 - 2  and CU-UP  404 - 2  and the reconfiguration of DU  406  is shown in  FIG.  1 C . As depicted, when data from UE  102  arrives at DU  406 , DU  406  forwards the data to CU-UP  404 - 2  over a new path  108 , and CU-UP  404 - 2  forwards the data received from DU  406  to UPF  306 - 2 . By selecting CU-UP  404 - 2  and UPF  306 - 2  based on their locations (e.g., proximity to DU  406 ) and inserting CU-UP  404 - 2  and UPF  306 - 2  in the data path, the system can minimize latency. 
       FIG.  2    illustrates an exemplary network environment  200  in which the systems and methods described herein may be implemented. As shown, environment  200  may include UE  102  (also UEs  102 ), an access network  204 , a core network  206 , and an external network  214 . 
     UE  102  may include a wireless communication device, a mobile terminal, or a fixed wireless access (FWA) device. Examples of UE  102  include: a smart phone; a tablet device; a wearable computer device (e.g., a smart watch); a laptop computer; an autonomous vehicle with communication capabilities; a portable gaming system; and an Internet-of-Thing (IoT) device. In some implementations, UE  102  may correspond to a wireless Machine-Type-Communication (MTC) device that communicates with other devices over a machine-to-machine (M2M) interface, such as Long-Term-Evolution for Machines (LTE-M) or Category M1 (CAT-M1) devices and Narrow Band (NB)-IoT devices. UE  102  may send packets to or over access network  204 . 
     Access network  204  may allow UE  102  to access core network  206 . To do so, access network  204  may establish and maintain, with participation from UE  102 , an over-the-air channel with UE  102 ; and maintain backhaul channels with core network  206 . Access network  204  may convey information through these channels, from UE  102  to core network  206  and vice versa. 
     Access network  204  may include a Long-Term Evolution (LTE) radio network, a Fifth Generation (5G) radio network and/or another advanced radio network. These radio networks may operate in many different frequency ranges, including millimeter wave (mmWave) frequencies, sub 6 GHz frequencies, and/or other frequencies. Access network  204  may include many wireless stations and devices herein referred to as Integrated Access and Backhaul (IAB) nodes. In  FIG.  2   , these are depicted as a wireless station  208  and IAB nodes  210 . Wireless station  208  and IAB nodes  210  may establish and maintain an over-the-air channel with UE  102  and backhaul channels with core network  206 . 
     Wireless station  208  may include a Fourth Generation (4G), 5G, or another type of wireless station (e.g., evolved Node B (eNB), next generation Node B (gNB), etc.) that includes one or more Radio Frequency (RF) transceivers. In  FIG.  2   , wireless station  208  is depicted as receiving a backhaul wireless link from IAB nodes  210 . A wireless station  208  that is attached to an IAB node via a backhaul link is herein referred to as IAB donor  208 . As used herein, the term “IAB donor” refers to a specific type of IAB node. IAB donor  208  may have the capability to act as a router. 
     TAB nodes  210  may include one or more devices to relay signals from IAB donor  208  to UE  102  and from UE  102  to IAB donor  208 . An TAB node  210  may have an access link with UE  102  and have a wireless and/or wireline backhaul link to other IAB nodes  210  and/or IAB donor  208 . An TAB node  210  may have the capability to operate as a router, for exchanging routing information with IAB donor  208  and other TAB nodes  210  and for selecting traffic paths. 
     As further shown, access network  204  may include a Multi-Access Edge Computing (MEC) cluster  212 . MEC cluster  212  may be located geographically close to wireless stations, and therefore also be close to UEs  102  serviced by the wireless station. Due to its proximity to UEs  102 , MEC cluster  212  may be capable of providing services to UEs  102  with minimal latency. Depending on the implementations, MEC cluster  212  may provide many core network functions at network edges. In other implementations, MEC cluster  212  may be positioned at other locations (e.g., in core network  206 ) at which MEC cluster  212  can provide computational resources for improved performance. 
     Core network  206  may include a local area network (LAN), a wide area network (WAN), a metropolitan area network (MAN), an optical network, a cable television network, a satellite network, a wireless network (e.g., a Code Division Multiple Access (CDMA) network, a general packet radio service (GPRS) network, an LTE network (e.g., a 4G network), a 5G network, an ad hoc network, a telephone network (e.g., the Public Switched Telephone Network (PSTN), an intranet, or a combination of networks. Core network  206  may allow the delivery of Internet Protocol (IP) services to UE  102 , and may interface with other networks, such as external network  214 . 
     Depending on the implementation, core network  206  may include 4G core network components (e.g., a Serving Gateway (SGW), a Packet data network Gateway (PGW), a Mobility Management Entity (MME), etc.), 5G core network components (e.g., a User Plane Function (UPF), an Application Function (AF), an Access and Mobility Function (AMF), a Session Management Function (SMF), a Unified Data Management (UDM) function, a Network Slice Selection Function (NSSF), a Policy Control Function (PCF), etc.), or another type of core network components. 
     External network  214  may include networks that are external to core network  206 . In some implementations, external network  214  may include packet data networks, such as an Internet Protocol (IP) network. 
     For simplicity,  FIG.  2    does not show all components that may be included in network environment  200  (e.g., routers, bridges, wireless access point, additional networks, additional UEs  102 , wireless station  208 , IAB nodes  210 , MEC clusters  212 , etc.). Depending on the implementation, network environment  200  may include additional, fewer, different, or a different arrangement of components than those illustrated in  FIG.  2   . Furthermore, in different implementations, the configuration of network environment  200  may be different. For example, wireless station  208  may not be linked to IAB nodes  210  and may operate in frequency ranges (e.g., sub-6 GHz) different from or same as those used by IAB nodes  210  (e.g., mmWave or another frequency range). 
     As indicated above, network environment  200  may include the system for selecting and using network components, based on their physical locations, for rerouting traffic from UE  102  to different endpoints.  FIGS.  6  and  10    (to be described below) show the components, of the system. Some of the components have been illustrated in  FIGS.  1 A- 1 C . Because the components of the system are also components of core network  206  and wireless station  208 , the components are described with reference to the figures that depict the components of core network  206  and wireless station  208  (i.e.,  FIGS.  3  and  4   ). 
       FIG.  3    illustrates exemplary functional components of core network  206 . In this implementation, core network  206  may include 5G core components, such as Access and Mobility Function (AMF)  302 , a Session Management Function (SMF)  304 , a User Plane Function (UPF)  306 , and a Policy Control Function (PCF)  308 . Depending on the implementation, core network  206  may include additional, fewer, or different core components than those illustrated in  FIG.  3   . Furthermore, depending on the implementation, through network slicing and network virtualization, core components  302 - 308  and other core components may be implemented in a data center or MEC cluster  212  in access network  204  or in external network  214 —the core components may be integrated into networks other than core network  206 . 
     AMF  302  may perform registration management, connection management, reachability management, mobility management, lawful intercepts, Short Message Service (SMS) transport between UE  102  and an SMS function (not shown), session management message transport between UE  102  and SMF  304 , access authentication and authorization, location services management, management of non-3GPP access networks, and/or other types of management processes. 
     SMF  304  may perform session establishment, modification, and/or release, perform IP address allocation and management, perform Dynamic Host Configuration Protocol (DHCP) functions, perform selection and control of UPF  306 , configure traffic steering at UPF  306  to guide traffic to the correct destination, terminate interfaces toward PCF  308 , perform lawful intercepts, charge data collection, support charging interfaces, terminate session management of Non-Access Stratum (NAS) messages, perform downlink data notification, manage roaming functionality, and/or perform other types of control plane functions for managing user plane data. 
     UPF  306  may maintain an anchor point for intra/inter-Radio Access Technology (RAT) mobility, maintain an external protocol data unit (PDU) point of interconnect to a data network (e.g., external network 2  214 ), perform packet routing and forwarding, perform the user plane part of policy rule enforcement, perform packet inspection, perform lawful intercept, perform traffic usage reporting, perform Qualify-of-Service (QoS) handling in the user plane, perform uplink traffic verification, perform transport level packet marking, perform downlink packet buffering, send and forward an “end marker” to a radio access network node (e.g., gNB), and/or perform other types of user plane processes. 
     In some implementations, UPF  306  may load, from PCF  308 , a Policy and Charging Control (PCC) rule that requires UPF  306  to redirect UE  102 -originated IP data to a selected endpoint. After loading the PCC rule, UPF  306  may forward UE  102 -originated IP data to the selected endpoint. 
     PCF  308  may support policies to control network behavior, provide policy rules to control plane functions (e.g., to SMF  304 ), access subscription information relevant to policy decisions, perform policy decisions, and/or perform other types of processes associated with policy enforcement. In some implementations, PCF  308  may include a PCC rule for a node to redirect UE  102 -originated IP traffic to a selected endpoint. 
       FIG.  4    illustrates an exemplary functional components of a wireless station  208 . In  FIG.  4   , wireless station  208  is depicted as a 5G wireless station (e.g., gNB) and may include a Central Unit-Control Plane (CU-CP)  402 , a Control Unit-User Plane (CU-UP)  404 , a Distributed Unit (DU)  406 , and a Radio Unit (RU)  408 . Depending on the implementation, wireless station  208  may include additional, fewer, and/or different components than those illustrated in  FIG.  4   . For example, wireless station  208  may include multiple DUs  406  and RUs  408 . Furthermore, although components  402 - 408  are depicted as being included in wireless station  208 , each of components  402 - 408  may be implemented in access network  204  without being confined to a specific wireless station  208 . Furthermore, CU-CP  402  and CU-UP  404  may be implemented in MEC cluster  212  or in a data center as part of a network slice through network function virtualization. 
     CU-CP  402  may perform control plane signaling associated with managing DU  406  over F1-C interface  410 . CU-CP  402  may signal to DU  406  over a control plane communication protocol stack that includes, for example, F1AP (e.g., the signaling protocol for F1 interface between a CU and a DU). CU-CP  402  may include protocol layers comprising: Radio Resource Control (RRC) layer and a Packet Data Convergence Protocol-Control Plane (PDCP-C). DU  406  may include corresponding stacks to handle/respond to the signaling (not shown). 
     CU-UP  404  may perform user plane functions associated with managing DU  406  over F1-U interface  412 . CU-UP  404  may interact with DU  406  over a user plane communication protocol stack that includes, for example, General Packet Radio Service Tunneling Protocol (GTP)-User plane, the User Datagram Protocol (UDP), and the IP. DU  406  would have corresponding layers to handle/respond to messages from CU-UP  404  (not shown). CP-UP  404  may include processing layers that comprise a Service Data Adaptation Protocol (SDAP) and a PDCP-User Plane (PDCP-U). CU-UP  404  and CU-CP  402  communicate over E1 interface, for example, for exchanging bearer setup messages. 
     Although CU-CP  402  and CU-UP  404  (collectively referred to as CU) and DU  406  are illustrated as part of wireless station  208 , the CU-CP  402 , CU-UP  404 , and DU  406  do not need to be physically located close to one another, as CU-CP  402  and CU-UP  404  may be implemented as cloud computing elements, through network function virtualization capabilities of the cloud. A CU may communicate with the components of core network  206  through S1/NG interfaces and with other CUs through X2/Xn interfaces. 
     DU  406  may provide support for one or more cells covered by radio beams at the RU  408 . DU  406  may handle UE mobility, from a DU to a DU, gNB to gNB, cell to cell, beam to beam, etc. RU  408  may perform physical layer functions, such as antenna functions, transmissions of radio beams, etc. 
     As indicated above, the system described herein permit network functions to change traffic paths/routes, by selecting network nodes based on their geographical locations and inserting the selected nodes in the paths. Some of the components of the system have been described above. In particular, DU  406  has been described above with reference to  FIG.  4   . DU  406  can be part of other network components, however. For example, DU  406  may be included in each of IAB nodes  210 . 
       FIG.  5 A  illustrates an exemplary network layout of IAB nodes  210 . As shown, some IAB nodes  210  may be attached to wireless station  208  (e.g., gNB), otherwise referred to as IAB donor  208 , and to other IAB nodes  210  through backhaul links. Each IAB node  210  may have a parent node upstream (e.g., either a parent IAB node  210  or IAB donor  208 ) and a child node downstream (e.g., either a UE  102  or a child IAB node  210 ). An IAB node  210  that has no child IAB node  210  is herein referred to as a leaf IAB node  210 . UE  102  may establish an access link with any of IAB nodes  210  and not just leaf IAB nodes  210 . 
       FIG.  5 B  illustrates exemplary functional components of IAB donor  208  and IAB nodes  210  in  FIGS.  2  and  5 A . In  FIG.  5 B , although only a single IAB node  210 - 1  is shown to be between IAB node  210 - 2  and IAB donor  208 , in other embodiments, there may be many IAB nodes  210  between an IAB node  210 - 2  and IAB donor  208 . Furthermore, although,  FIG.  5 B  shows only a single path from IAB node  210 - 2  to IAB donor  208 , there may be one or more paths from each IAB node  210 - 2  to IAB donor  208 . As shown, IAB donor  208  includes CU-CP  402 , CU-UP  404 , and DU  406 -D; IAB node  210 - 1  includes MT  518 - 1  and DU  406 - 1 ; and IAB node  210 - 2  includes MT  518 - 2  and DU  406 - 2 . 
     In  FIG.  5 B , the control plane connections from CU-CP  402  and CU-UP  404  in IAB donor/wireless station  208  are shown as terminating at DU  406 - 2  in IAB node  114 - 2 . However, for the path between IAB donor  208  and IAB node  210 - 1 , CU-CP  402  and CU-UP  404  would terminate their connections at DU  406 - 1  in IAB node  210 - 1 , although not shown in  FIG.  5 B . 
     Each of MTs  518 - 1  and  518 - 2  permits its host device to act like a mobile terminal (e.g., UE  102 ). For example, to DU  406 -D in IAB donor  208 , MT  518 - 1  in IAB node  210 - 1  behaves similarly as a mobile terminal wirelessly attached to DU  406 -D. The relationship between MT  518 - 1  and DU  406 -D, and between MT  518 - 2  and DU  406 - 1 , is established over a Backhaul (BH) channel  526  between DU  406 -D of IAB donor  208  and MT  518 - 1  of IAB node  210 - 1  and over BH channel  528  between DU  406 - 1  of IAB node  210 - 1  and MT  518 - 2  of IAB node  210 - 2 . 
     Each of BH channels  526  and  528  in  FIG.  5 B  includes multiple network layers that comprise, for example, a Backhaul Adaptation Layer (BAP), a Radio Link Control (RLC), a Media Access Control (MAC), and a Physical layer (PHY. These layers are not illustrated in  FIG.  5 B . 
     As BH channels may be RF channels, IAB nodes  210  may be part of access network  204  through wireless connections and therefore do not need to be interconnected through cables or optical fibers. In contrast to other wireless stations that are bound to access network  204  through cables or optical fibers, IAB nodes  210  may be placed in locations where cables or fibers are difficult to lay, and therefore, may easily provide access points for UEs  102 . If necessary, IAB nodes  210  may be moved from one geographical location to another without re-cabling, as communication demands at different locations change. 
       FIG.  6    illustrates exemplary functional components of the system  600  for changing traffic paths/routes, by selecting network nodes based on their physical locations and inserting the selected nodes in the paths. As shown, system  600  may include AMF  302 , SMF  304 , UPF  306 , PCF  308 , CU-CP  402 , CU-UP  404 , and DU  406 . Although system  600  may include multiple instances of AMF  302 , SMF  304 , UPF  306 , PCF  308 , CU-CP  402 , CU-UP  404 , and DU  406 , they are not illustrated in  FIG.  6   . Also, depending on the implementation, system  600  may include fewer or additional components than those shown in  FIG.  6   . For example, in some implementations, system  600  may not include PCF  308  for setting network policies on selecting nodes for routing traffic based on the locations of the nodes. In another example, system  600  may include a Network Repository Function (NRF) for component registration and/or storing network component identifiers, location IDs, instance IDs, etc. 
     As part of system  600 , PCF  308  may send messages to AMF  302  and/or SMF  304 , indicating that AMF  302  and/or SMF  304  are to enforce location based selections of UPF  306  and CU-UP  404  for routing UE-originated data between DU  406  and an endpoint (e.g., an endpoint in MEC cluster  212 , external network  214 , or another network). 
     As part of system  600 , when SMF  304  receives the message from PCF  308 , SMF  304  ensures that the Internet Protocol (IP) address fields of its messages to/from UPF  306  include location information or follows a particular format. In other implementations, UPF  306  may follow the format without receiving any message from SMF  304 .  FIG.  7 A  shows the format, according to an implementation. In  FIG.  7 A , the address  702  is an IP version 6 (IPv6)  702 , which is 128 bits long. The IPv6 address  702  may include several fields, such as General Routing Prefix and Subnet Identifier (ID) field  704  and other fields that are implementation dependent. For the system described herein, the other fields include a location ID field  706 , an Element ID field  708 , a to-be-determined (TBD) field  710 , and an Element Instance ID field  712 . 
     General Routing Prefix and Subnet ID field  702  is 64 bits long and identifies the address of the network. Location ID field  706  includes a code (e.g., an alphanumeric value, a numeric value, etc.) that identifies the physical location of the source/destination. For example, if number  40  is a code for a particular location (e.g., a shelf location, a site location, an area location, etc.), and the network element that sent the message with the IPv6 address is at the location, then Location ID  706  may include number  40 . 
     Element ID field  708  indicates a type of network function that is the source or the destination of the packet that carries the IPv6 address. For example, Element ID field  708  within an IPv6 address of a message from UPF  306  may indicate that the element type is “UPF.” TBD field  710  may be yet to be determined. Element Instance ID field  712  may indicate a particular instance of an element type. For example, if there are 10 instances of UPF  306  implemented on hardware at a data site, each one of the UPF instances may be identified by the Element Instance ID. Element Instance ID field  712  may carry the element instance ID of the instance which sent the message with the IPv6 address that includes the Element Instance ID field  712 . 
     Referring back to  FIG.  6   , after SMF  304  receives the messages from PCF  308  on selecting UPF  306  based on its location, SMF  306  may use Network Repository Function (NRF) (not shown) to determine the UPF  306  that is closest to a given site (e.g., a MEC cluster  212  site). At the NRF, a MEC cluster site can be referred to using Data Network Access Identifier (DNAI). Within NRF, each UPF  306  may be registered with DNAIs for the data networks (DNs) that the UPF  306  can support. In a different embodiment, SMF  304  may have locally stored information on UPFs  306  and the corresponding DNAIs. 
     In addition, when UPF  306  sends messages to other network components, the messages may include IPv6 source address whose Location ID field  706  indicates the location of the UPF  306 . When SMF  304  receives messages from different UPFs  306 , SMF  304  extracts the location IDs of UPFs  306  and stores the location IDs, along with corresponding IDs for the UPFs  306  (e.g., Element Instance IDs  712 ). Accordingly, SMF  304  builds a lookup table of locations for UPFs  306 . Given an identifier or coordinates of a location, 
     In system  600 , a network component (e.g., PCF  308 , AMF  302 , etc.) may request SMF  304  to select a UPF  306  that can break out traffic to a particular edge site. In response to the request, SMF  304  may query the NRF or use the look up table of UPF locations, to identify a UPF  306  whose location is closest to a reference location provided by the requesting network component. Furthermore, SMF  304  may notify other network components about the location of the selected UPF  306 . For example, SMF  304  may send a message to AMF  302  or to CU-CP  402 , identifying the newly selected UPF  306  and its location. In system  600 , a message that identifies the location of UPF  306  may include what is referred to herein as information Elements (IEs). Thus, if SMF  304  sends a message that indicates the location of UPF  308 , the message may include IEs that specifically identify the location of the UPF  306 . 
     The types of IEs that identify the location of UPF  306  may be included in various messages between network components of access network  204 , core network  206 , and/or external network  214 . For example, in one implementation, SMF  304  may send a message, to CU-CP  402 , requesting CU-CP  402  to modify its resources when SMF  304  selects a new UPF  306  based on its physical location. More specifically, SMF  304  may send a Protocol Data Unit (PDU) Session Resource Modify Request message. The message may include IEs that identify the location of a selected UPF  306 , as well as other IEs. 
       FIG.  7 B  illustrates some IEs that are included in the PDU Session Resource Modify Request message  720 . As shown, message  720  includes a list IE. The list IE is PDU SESSION RESOURCE MODIFY LIST. The list comprises other IEs, each of which is PDU SESSION RESOURCE MODIFY REQUEST ITEM. One of these IEs includes PDU SESSION RESOURCE MODIFY REQUEST TRANSFER. The IE indicates that the request for changing resource is for a transfer of a resource. 
     As further shown in  FIG.  7 B , PDU SESSION RESOURCE MODIFY REQUEST  730  in turn comprises an Uplink Next Generation to UE Transport Network Layer Modify List (UL NG-U TNL MODIFY LIST). The IE indicates that the transfer involves the transport layer connection between UE  102  and an endpoint. As further shown in  FIG.  7 B , UL NG-U TNL MODIFY LIST includes UL NG-U UP TNL MODIFY ITEMs. UL NG-U TNL MODIFY ITEM includes a UL NG-U TNL MODIFY INFORMATON. The IE identifies components of a tunnel. 
     As further shown, UL NG-U TNL MODIFY INFORMATION  7740  comprises a CHOICE User Plane (UP) TRANSPORT LAYER INFORMATION, which includes GTP TUNNEL. GTP TUNNEL in turn includes an ENDPOINT IP ADDRESS and a UPF LOCATION INFORMATION. These IEs include the IP address of the UPF  306  and location information (e.g., a location ID) associated with the UPF  306 . 
     In  FIG.  7 B , not all IEs for PDU Session Resource Modify Request  720  are shown. Furthermore, not all IEs that are included in other IEs are shown. For example, the GTP TUNNEL may include IEs other than the ENDPOINT ADDRESS or the UPF LOCATION INFORMATION. Similarly, IE  730  may include IEs other than those shown in  FIG.  7 B . 
     Referring back to  FIG.  6   , CU-CP  402  may comprise a lookup table that indicates locations of CU-UPs  404 . In other implementations, each of CU-UPs  404  is co-located with a corresponding UPF  306 , and in such implementations, CU-CP  402  may not include or use a lookup table of locations for CU-UPs  404 . When CU-CP  402  receives appropriate signaling (e.g., from AMF  302  or SMF  304 ), CU-CP  402  may send configuration information, over E1 interface, to CU-UP  404  that is co-located with a UPF  306  identified by the signaling. In a different implementation, CU-CP  402  may select a CU-UP  404  based on the location of CU-UP  404  and the location of the UPF  306  identified in the signaling, by using the lookup table of CU-UPs  404  and their location IDs. 
       FIG.  8    is a processing diagram that is associated with system  600  modifying a traffic path between a UE  102  and an endpoint, by inserting a UPF  306  and CP-UP  404  in the path.  FIG.  9    depicts signaling paths between different network components of system  600  during the process of  FIG.  8   . The process may be performed by various components of system  600 . 
     As shown in  FIG.  8   , the process may begin with UE  102  establishing a connection with UPF  306 - 1  as a Protocol Data Unit session anchor (PSA) point (block  802 ). Through UPF  306 - 1 , UE  102  may establish a session with an application in a network portion to which UPF  306 - 1  serves as a gateway. 
     Referring to  FIG.  9   , establishing the session may start with UE  102  establishing a connection with DU  406  over a Data Radio Bearer (DRB). When DU  406  receives a request for session from UE  102 , DU  406  may send a UE context message to CU-CP  402  over path  902 , over F1-C interface. A context message may include a DRB identifier (DRB ID or DRB #), possibly an identifier associated with a network slice, such as Single-Network Slice Selection Assistance Information (S-NSSAI) (provided by UE  102  in its session request), a QoS Flow level parameter, and/or other information. When CU-CP  402  receives the UE context and/or other information from a DU  406 , CU-CP  402  may send a message to AMF  302  over path  904  (N4 interface) requesting a session establishment/modification. In one implementation, CU-CP  402  is aware of the identity of DU  406  that sent the message and may look up the physical location of DU  406 . CU-CP  402  may store the location information for later use. 
     When AMF  302  receives the request for session from CU-CP  402 , in response, AMF  302  may request, over path  906 , SMF  304  to create or modify a session. Upon receipt of the message, SMF  304  may select a UPF  306 - 1  based on the endpoint with which UE  102  is to establish the session. SMF  304  may exchange signals with UPF  306 - 1  over path  908  to set UPF  306 - 1  as a PSA point. SMF  304  then messages AMF  302  about the UPF  306 - 1 , indicating the location of UPF  306 - 1 , in an IE within the message, over path  906 . 
     After AMF  302  receives the message, AMF  302  may inform CU-CP  402  over path  904 , that the anchor point is set. At this juncture, depending on the implementation, CU-CP  402  may be aware of the location of UPF  306 - 1  (if AMF  304  indicates the location of UPF  306 - 1  in its message through IEs). Furthermore, depending on the implementation, CU-CP  402  may select CU-UP  404 - 1  based on the locations of available CU-CPs  404  and the location of UPF  306 - 1  (e.g., by using its internal lookup table of CU-UPs  404  and their location information). For example, CU-CP  402  may select the CU-UP  404  that is closest to DU  406  and/or UPF  306 - 1 . In other implementations, a default CU-UP  404 - 1  that is associated with UPF  306 - 1  may be selected, without accounting for the locations of CU-UPs  404  and/or UPF  306 - 1 . After selecting CU-UP  404 - 1 , CU-CP  402  may send a bearer context message over path  910  (E1 interface) so that CU-UP  404 - 1  can map the DRB to a particular flow path  912 . Once the mapping is complete, the requested session can be established from UE  102  to the endpoint via UPF  306 - 1 . Thereafter, CU-UP  404 - 1  can receive session data from DU  406  over path  914  (F1-U) and forward the data to UPF  306 - 1 , over path  912 . CU-UP  404 - 1  may also forward session data received from UPF  306 - 1  to DU  406 . DU  406  may forward any uplink data to CU-UP  404  and downlink data to UE  102 . 
     Referring back to  FIG.  8   , SMF  304  may receive a message from PCF  308  instructing SMF  304  to support a particular application (e.g., an application in MEC cluster  212 ) (block  804 ) for the established session and provide SMF  304  with a Data Network Access Identifier (DNAI) and/or a location ID associate d with the DN. In some implementations, given the DNAI, SMF  304  may be configured to lookup the location ID for the DNAI. 
     In response to the instruction from PCF  308 , SMF  304  may select and establish a PSA point with UPF  306 - 2  (e.g., UL CL) that corresponds to the DNAI. In  FIG.  9   , after the receipt of the instruction from PCF  308 , SMF  304  may exchange signals with UPF  306 - 2  over path  916 , to set UPF  306 - 2  as a PSA point for the existing session. SMF  304  may store the IPv6 address of UPF  306 - 2  and/or its location ID (see  FIG.  7 A ) for later use. 
     In addition to setting UPF  306 - 2  as a PSA point, SMF  304  may also signal UPF  306 - 1 , to make any necessary configuration changes associated with UPF  306 - 1  so that UPF  306 - 1  no longer receives traffic from UE  102  through CU-UP  404 - 1  (e.g., tear down path  912 ). SMF  304  may signal UPF  306 - 1  to have UPF  306 - 1  receive traffic from UE  102  through UPF  306 - 2 , and signal UPF  306 - 2  to forward some of the traffic from UE  102  to UPF  306 - 1 . 
     Next, SMF  304  may send the IP address of UPF  306 - 2  (e.g., IPv6 address) (block  808 ) to access network  204 . More specifically, SMF  304  may send the IP address of UPF  306 - 2  and/or its location information (e.g., location ID) to CU-CP  402  in a PDU Session Resource Modify Request  720  ( FIG.  7 A ). As described above, the request  720  may include the IEs that convey the location information and/or the IPv6 address. 
     Access network  204  may select a CU-UP  404 - 2  in response to the SMF  304  signaling (block  810 ). More specifically, when CU-CP  402  in access network  204  receives the signal and the location information from SMF  304 , CU-CP  402  may use the location information for UPF  306 - 2  and/or location information for DU  406 , to identify a CU-UP  404 - 2  that is closest (e.g., geographically) to UPF  306 - 2  and/or DU  404 . In a different implementation, a default CU-UP  404  for UPF  306 - 2  may exist, and in such an instance, CU-CP  402  may select the default CU-UP  404 , as CU-UP  404 - 2 . After the selection of CU-UP  404 - 2 , CU-CP  402  may configure CU-UP  404 - 2 , in a manner similar to that for configuring CU-UP  404 - 1 , over path  918  (e.g., E1 interface). Once configured, CU-UP  404 - 2  may exchange data with DU  406  over path  920  (F1-U) and with UPF  306 - 2  over path  922 . Furthermore, CU-CP  402  may signal CU-UP  404 - 1  so that CU-CP  404 - 1  no longer relays data between DU  406  and UPF  306 - 1 . CU-UP  404 - 1  may release any resources it allocated for relaying the data. 
       FIG.  10    shows a processing diagram that is associated with modifying a UP traffic path between UE  102  an endpoint when UE  102  moves from one location to another location.  FIG.  11    depicts signaling paths between different network components for system  600  during the process of  FIG.  10   . The process may be performed by various components of system  600 . 
     As shown in  FIGS.  10  and  11   , the process may begin with UE  102  at location  1102 - 1  establishing a connection with UPF  306 - 1  as a PSA point (block  1002 ). For block  1002 , the signaling between the components of system  600  as shown in  FIG.  11    are similar to those illustrated in  FIG.  9    for block  802 , except that in  FIG.  11   , DU  406 - 1  replaces DU  406  in  FIG.  9   . After establishing the session, UE  102  then moves to location  1102 - 2  (block  1003 ), causing various network components to proceed with a handover process (block  1004 ). 
     Referring to  FIG.  11   , the handover may start with UE  102  establishing a connection with DU  406 - 2  over a DRB. When DU  406 - 2  receives a request for session from UE  102 , DU  406 - 2  may send a UE context message to CU-CP  402  over path  1105 , over F1-C interface. A context message may include a DRB identifier (DRB ID or DRB #), possibly an identifier associated with a network slice, such as S-NSSAI (provided by UE  102  in its session request), a QoS Flow level parameter, and/or other information. When CU-CP  402  receives the UE context and/or other information from a DU  406 , CU-CP  402  may send a message to AMF  302  over path  904  (N4 interface) requesting a session modification. In one implementation, CU-CP  402  is aware of the identity of DU  406 - 2  that sent the context message and may look up the physical location of DU  406 - 2 . CU-CP  402  may store the location information for later use. 
     When AMF  302  receives the request for session from CU-CP  402 , AMF  302  may request, over path  906 , SMF  304  to modify or create a session. In  FIG.  10   , after the receipt of the request from AMF  302 , SMF  304  may exchange signals with UPF  306 - 2  over path  916 , to set UPF  306 - 2  as a PSA point for the session (block  1006 ). SMF  304  may store the IPv6 address of UPF  306 - 2  and/or its location ID (see  FIG.  7 A ) for later use. 
     In addition to setting UPF  306 - 2  as the PSA point, SMF  304  may also signal UPF  306 - 1 , to make any necessary configuration changes associated with UPF  306 - 1  so that UPF  306 - 1  no longer receives traffic from UE  102  through CU-UP  404 - 1  (e.g., tear down path  912 ). SMF  304  may signal UPF  306 - 1  to have UPF  306 - 1  receive none or some of the traffic from UE  102  through UPF  306 - 2 , and signal UPF  306 - 2  to forward some of the traffic from UE  102  to UPF  306 - 1 , over path  924 . 
     Next, SMF  304  may reply to AMF  302 , indicating that the session has been modified. SMF  304  may send, in the reply, the IEs that include the IP address of UPF  306 - 2  (e.g., IPv6 address) and/or UPF  306 - 2  location ID (block  1008 ). In response, AMF  302  may send a message to CU-CP  402 , indicating that the session is modified. The message may include the IEs which indicate the IPv6 address of UPF  306 - 2  and/or location information for UPF  3065 - 2  (block  1008 ). 
     Access network  204  may select a CU-UP  404 - 2  in response to the AMF  304  reply (block  1010 ). More specifically, when CU-CP  402  in access network  204  receives the signal and the location information from AMF  302 , CU-CP  402  may use the location information for UPF  306 - 2  and the location information for DU  406 - 2 , to identify a CU-UP  406 - 2  that is closest to UPF  306 - 2  and/or DU  406 - 2  (e.g., by using its internal table of CU-UPs  404  and their locations). In a different implementation, a default CU-UP  404  for UPF  306 - 2  may exist, and in such an instance, CU-CP  402  may select the default CU-UP  404 , as CU-UP  404 - 2 . After the selection of CU-UP  404 - 2 , CU-CP  402  may configure CU-UP  404 - 2 , in a manner similar to that for configuring CU-UP  404 - 1 , over path  918  (e.g., E1 interface). In addition, CU-CP  402  may send a reply to the UE context message sent by DU  404 - 2 . 
     Once configured, CU-UP  404 - 2  may exchange data with DU  406 - 2  over path  1120  (F1-U) and with UPF  306 - 2  over path  922 . Furthermore, CU-CP  402  may signal CU-UP  404 - 1  so that CU-CP  404 - 1  no longer relays data between DU  406 - 1  and UPF  306 - 1 . CU-UP  404 - 1  may release any resources it allocated for relaying the data. 
       FIG.  12    depicts exemplary components of an exemplary network device  1200 . Network device  1200  corresponds to or is included in UE  102 , IAB nodes  210 , and any of the network components of  FIGS.  1 - 6  and  8 - 11    (e.g., a router, a network switch, servers, gateways, wireless stations  208 , MEC cluster  212 , CU-CP  402 , CU-UP  404 , DU  406 , CU, etc.). As shown, network device  1200  includes a processor  1202 , memory/storage  1204 , input component  1206 , output component  1208 , network interface  1210 , and communication path  1212 . In different implementations, network device  1200  may include additional, fewer, different, or a different arrangement of components than the ones illustrated in  FIG.  12   . For example, network device  1200  may include a display, network card, etc. 
     Processor  1202  may include a processor, a microprocessor, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a programmable logic device, a chipset, an application specific instruction-set processor (ASIP), a system-on-chip (SoC), a central processing unit (CPU) (e.g., one or multiple cores), a microcontroller, and/or another processing logic device (e.g., embedded device) capable of controlling network device  1200  and/or executing programs/instructions. 
     Memory/storage  1204  may include static memory, such as read only memory (ROM), and/or dynamic memory, such as random access memory (RAM), or onboard cache, for storing data and machine-readable instructions (e.g., programs, scripts, etc.). 
     Memory/storage  1204  may also include a CD ROM, CD read/write (R/W) disk, optical disk, magnetic disk, solid state disk, holographic versatile disk (HVD), digital versatile disk (DVD), and/or flash memory, as well as other types of storage device (e.g., Micro-Electromechanical system (MEMS)-based storage medium) for storing data and/or machine-readable instructions (e.g., a program, script, etc.). Memory/storage  1204  may be external to and/or removable from network device  1200 . Memory/storage  1204  may include, for example, a Universal Serial Bus (USB) memory stick, a dongle, a hard disk, off-line storage, a Blu-Ray® disk (BD), etc. Memory/storage  1204  may also include devices that can function both as a RAM-like component or persistent storage, such as Intel® Optane memories. 
     Depending on the context, the term “memory,” “storage,” “storage device,” “storage unit,” and/or “medium” may be used interchangeably. For example, a “computer-readable storage device” or “computer-readable medium” may refer to both a memory and/or storage device. 
     Input component  1206  and output component  1208  may provide input and output from/to a user to/from network device  1200 . Input and output components  1206  and  1208  may include, for example, a display screen, a keyboard, a mouse, a speaker, actuators, sensors, gyroscope, accelerometer, a microphone, a camera, a DVD reader, Universal Serial Bus (USB) lines, and/or other types of components for obtaining, from physical events or phenomena, to and/or from signals that pertain to network device  1200 . 
     Network interface  1210  may include a transceiver (e.g., a transmitter and a receiver) for network device  1200  to communicate with other devices and/or systems. For example, via network interface  1210 , network device  1200  may communicate with wireless station  208 . 
     Network interface  1210  may include an Ethernet interface to a LAN, and/or an interface/connection for connecting network device  1200  to other devices (e.g., a Bluetooth interface). For example, network interface  710  may include a wireless modem for modulation and demodulation. 
     Communication path  1212  may enable components of network device  1200  to communicate with one another. 
     Network device  1200  may perform the operations described herein in response to processor  1202  executing software instructions stored in a non-transient computer-readable medium, such as memory/storage  1204 . The software instructions may be read into memory/storage  1204  from another computer-readable medium or from another device via network interface  1210 . The software instructions stored in memory or storage (e.g., memory/storage  1204 , when executed by processor  1202 , may cause processor  1202  to perform processes that are described herein. For example, UE  102 , AMF  302 , SMF  304 , UPF  306 , wireless station/IAB donor  208 , IAB nodes  210 , CU-CP  402 , CU-UP  404 , and DU  406  may each include various programs for performing some of the above-described functions and processes. 
     In this specification, various preferred embodiments have been described with reference to the accompanying drawings. Modifications may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense. 
     While a series of blocks have been described above with regard to the process illustrated in  FIGS.  8  and  10   , the order of the blocks may be modified in other implementations. In addition, non-dependent blocks may represent blocks that can be performed in parallel. 
     It will be apparent that aspects described herein may be implemented in many different forms of software, firmware, and hardware in the implementations illustrated in the figures. The actual software code or specialized control hardware used to implement aspects does not limit the invention. Thus, the operation and behavior of the aspects were described without reference to the specific software code—it being understood that software and control hardware can be designed to implement the aspects based on the description herein. 
     Further, certain portions of the implementations have been described as “logic” that performs one or more functions. This logic may include hardware, such as a processor, a microprocessor, an application specific integrated circuit, or a field programmable gate array, software, or a combination of hardware and software. 
     To the extent the aforementioned embodiments collect, store, or employ personal information provided by individuals, it should be understood that such information shall be collected, stored, and used in accordance with all applicable laws concerning protection of personal information. The collection, storage and use of such information may be subject to consent of the individual to such activity, for example, through well known “opt-in” or “opt-out” processes as may be appropriate for the situation and type of information. Storage and use of personal information may be in an appropriately secure manner reflective of the type of information, for example, through various encryption and anonymization techniques for particularly sensitive information. 
     No element, block, or instruction used in the present application should be construed as critical or essential to the implementations described herein unless explicitly described as such. Also, as used herein, the articles “a,” “an,” and “the” are intended to include one or more items. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.