Patent Description:
<NUM>rd Generation Partnership Project (3GPP) specifies interworking between <NUM>th Generation (<NUM>) communication networks and <NUM>th Generation (<NUM>) communication networks and also provides procedures in <NUM> Standalone (SA) architecture for enabling a <NUM> capable user equipment (UE) to handover from <NUM> New Radio (NR) to <NUM> Evolved UMTS Terrestrial Radio Access Network (EUTRAN) and vice-versa.

When a Protocol Data Unit (PDU) session is created on a <NUM> core for a UE, a User Plane Function (UPF) node is selected by a Session Management Function (SMF) to forward and process the data packets destined for and/or originating from the UE. During a handover of the UE from <NUM> to <NUM> EUTRAN, the Access and Mobility Management Function (AMF) node of the <NUM> network selects a <NUM> Mobility Management Entity (MME) node and initiates a context transfer to LTE core of the <NUM> EUTRAN network. As a part of this process, the MME node selects a Serving Gateway Control Plane (SGW-C) node and the SGW-C node in turn selects a Serving Gateway User Plane (SGW-U) node (in a Control and User Plane Separation of Evolved Packet Core nodes (CUPS) based LTE core). This SGW-C node then communicates with the Packet Gateway Control Plane (PGW-C) component of the SMF node to setup the LTE session.

Due to addition of SGW-U node in data path, the data to/from the UE in the <NUM> network now has one additional hop to travel (eNodeB-->SGW-U-->UPF-->Data Network (DN) for uplink and DN --> UPF --> SGW-U-->eNodeB for downlink). A typical user plane node can support functionalities of all SGW-U, PGW-U and UPF nodes. However in the currently defined 3GPP procedure for <NUM> to <NUM> handover, there is no mechanism for the SGW-C node to know whether the UPF node in the <NUM> core can also act as a SGW-U node in the <NUM> network for the UE. Also, SGW-C has no mechanism to know the identity of the UPF node selected by SMF node in <NUM> core. Hence, a SGW-C node, as of today, cannot guarantee selection of same user plane node to avoid the extra hop in data path as mentioned above. This lack of guarantee of the selection of the same user plane node as the SGW-U results in the above four-hop process, examples of which are visually depicted in <FIG> and <FIG>.

<FIG> illustrates an example of a four-hop process after a <NUM> to <NUM> handover of a UE. As noted above, the handover process currently specified by 3GPP does not guarantee that the same user plane node <NUM> used as the UPF node in the <NUM> network for UE <NUM> is again selected as the SGW-U for UE <NUM> when UE <NUM> is handed over to the <NUM> network (from the <NUM> plane to the <NUM> plane shown in <FIG>). Instead, SGW-U <NUM> may have been selected. Therefore, any communication between UE <NUM> and DN <NUM> involves UE <NUM> communicating with eNB <NUM> (D1), eNB <NUM> communicating with the selected SGW-U <NUM> (D2), SGW-U <NUM> communicating with the old SGW-U + UPF/PGW-U node <NUM> (D3) and SGW-U + UPF/PGW-U node <NUM> communicating with DN <NUM> (D4). Therefore, a data path between UE <NUM> and DN <NUM> includes D1->D2->D3->D4.

<FIG> illustrates another example of a four-hop process after a <NUM> to <NUM> handover of a UE. Similar to <FIG>, the handover process currently specified by 3GPP does not guarantee that the same user plane node <NUM> used as the UPF node in the <NUM> network for UE <NUM> is again selected as the SGW-U for UE <NUM> when handed over to the <NUM> network (from the <NUM> plane to the <NUM> plane shown in <FIG>). Instead, SGW-U <NUM> may have been selected. Therefore, any communication between UE <NUM> and DN <NUM> involves UE <NUM> communicating with eNB <NUM> (D1), eNB <NUM> communicating with the selected SGW-U <NUM> (D2), SGW-U <NUM> communicating with the old SGW-U + UPF/PGW-U node <NUM> (D3) and SGW-U + UPF/PGW-U node <NUM> communicating with DN <NUM> (D4). Therefore, a data path between UE <NUM> and DN <NUM> includes D1->D2->D3->D4.

This four-hop process in the data path can also add to latency and may impact the low latency requirement for <NUM> applications.

<CIT> is directed to Node Selection in a Packet Core Network.

Various example embodiments of the disclosure are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the scope of the disclosure. Thus, the following description and drawings are illustrative and are not to be construed as limiting. Numerous specific details are described to provide a thorough understanding of the disclosure. However, in certain instances, well-known or conventional details are not described in order to avoid obscuring the description. References to one or an embodiment in the present disclosure can be references to the same embodiment or any embodiment; and, such references mean at least one of the embodiments.

Disclosed are systems, methods, and computer-readable media for ensuring that when a <NUM> capable UE that is currently having an active communication session within a <NUM> or a <NUM> network, using a user plane PDN gateway (PGW-U)/UPF node, can be handed over to the other one of a <NUM> or a <NUM> network, where after the handover, the same user plane PDN gateway (PGW-U)/UPF node is selected as the SGW-U for the UE.

The disclosed technology addresses the need in the art for reducing a number of hops or network nodes through which a data packet can be exchanged between a user equipment and a data network within a <NUM> or a <NUM> network after the user equipment is handed over from a <NUM> network to a <NUM> network or vice-versa. In other words, the disclosed technology herein ensures an optimized user plane node selection process after the handover to ensure the reduction in the number of hops.

The disclosure begins with a description of example <NUM> network architecture.

<FIG> illustrates an example of network architecture and associated components, according to an aspect of the present disclosure. As shown in <FIG>, network <NUM> is a <NUM> wireless communication network. Network <NUM> can include a number of user equipment (UE) <NUM>. UEs <NUM> can be any type of known or to be developed device capable of establishing communication over a wireless/radio access technology with other devices. Examples of UEs <NUM> include, but are not limited to, various types of known or to be developed smart phones, laptops, tablets, desktop computers, Internet of Things (IoT) devices, etc..

UEs <NUM> can have multiple different radio access technology (RAT) interfaces to establish a wireless communication session with one or more different types of base stations (nodes) that operate using different RATs with network <NUM>. For example, a UE <NUM> can have a <NUM> interface as well as a <NUM> interface. Therefore, such UE <NUM> can be, from time to time and as the need may arise, be handed over from a <NUM> network to a neighboring <NUM> network and vice-versa.

Network <NUM> may also include nodes <NUM>, <NUM>, <NUM> and <NUM>. Nodes <NUM>, <NUM>, <NUM> and <NUM> can also be referred to as base stations or access points <NUM>, <NUM>, <NUM> and <NUM>. For example, node <NUM> can be a WiFi router or access point providing a small cell site or coverage area <NUM> for several of the UEs <NUM> therein. Therefore, node <NUM> may be referred to as a small cell node. Nodes <NUM> and <NUM> can be any one of various types of known or to be developed base stations providing one or more different types of Radio Access Networks (RANs) to devices connecting thereto. Examples of different RANs include, but are not limited to, Global System for Mobile Communication (GSM), General Packet Radio Service (GPRS)/Enhanced Data Rates for GSM Evolution (EDGE), Universal Mobile Telecommunications System (UMTS), Long-Term Evolution (LTE), LTE-advanced, Worldwide Interoperability for Microwave Access (WiMAX), WiFi, Code Division Multiple Access (CDMA), Evolution- Data Optimized (EV-DO), IS-<NUM> etc..

Node <NUM> can provide coverage area <NUM> for end points <NUM> within coverage area <NUM>. As shown in <FIG>, one or more UEs <NUM> can be located on an overlapping portion of coverage areas <NUM> and <NUM>. Therefore, such one or more UEs <NUM> can communicate with node <NUM> or node <NUM>.

Furthermore, node <NUM> can provide coverage area <NUM> for some of UEs <NUM> in coverage area <NUM>. Node <NUM> can provide coverage area <NUM> for all UEs <NUM> shown in <FIG>.

Within the <NUM> structure of network <NUM>, nodes <NUM>, <NUM>, <NUM> and <NUM> may operate in a connected manner to expand the coverage area provide by node <NUM> and/or to serve more UEs <NUM> than node <NUM> or some of the nodes <NUM>, <NUM>, <NUM> and <NUM> can handle individually. Node <NUM> may be communicatively coupled to node <NUM>, which may in turn be communicatively coupled to node <NUM>. Similarly node <NUM> can be communicatively coupled to node <NUM> and/or node <NUM>. Node <NUM> and node <NUM> can communicate with node <NUM> via any known or to be developed wireless communication standard. Also, node <NUM> can communicate with node <NUM> via any known or to be developed wireless communication standard.

Within network <NUM>, node <NUM> can have a wired connection to core network <NUM> via, for example, fiber optics cables. This may be referred to as backhaul <NUM> or backhaul connection <NUM>. While fiber optic cables is mentioned as one example connection medium for backhaul <NUM>, the present disclosure is not limited thereto and the wired connection can be any other type of know or to be developed wire.

Furthermore, each of nodes <NUM>, <NUM> and <NUM> can be any type of know or to be developed base station such as a next generation or <NUM> e-NodeB, which may also be referred to a global NodeB (gNB). Each of nodes <NUM> and <NUM> can have separate backhaul connections <NUM> and <NUM> to core network <NUM>. Connections <NUM> and <NUM> can be the same as backhaul connection <NUM>. In an example, where node <NUM> is a WiFi node, node <NUM> can connect to Core network <NUM> via a node <NUM>, which can be a N3 Interworking Function (N3IWF) node. Connection <NUM> between node <NUM> and Core network <NUM> can be the same as backhaul connection <NUM>.

<FIG> further illustrates a <NUM>/LTE network <NUM> which may overlap, geographically, with <NUM> network <NUM>. <NUM> network <NUM> may have a corresponding eNodeB <NUM> and <NUM>/LTE core <NUM>. For purposes of this disclosure, an assumption is made that UE <NUM> (e.g., UE <NUM> shown in <FIG> having a direct connection to anchor node <NUM>) can be handed over from <NUM> network <NUM> to <NUM> network <NUM> and vice-versa.

<FIG> illustrates another example architecture with components of core network <NUM> of <FIG>, according to an aspect of the present disclosure. A simplified version of network <NUM> is shown in <FIG>, where a single UE <NUM> has a wireless communication session established with anchor node <NUM>. Anchor node <NUM> is in turn connected to core network <NUM> via backhaul <NUM>.

Furthermore, <FIG> illustrates example logical components of core network <NUM>. Example components/nodes of core network <NUM> include various network functions implemented via one or more dedicated and/or distributed servers (can be cloud based). Core network <NUM> of <NUM> network <NUM> can be highly flexible, modular and scalable. It can include many functions including network slicing. It offers distributed cloud-based functionalities, Network functions virtualization (NFV) and Software Defined Networking (SDN).

For example and as shown in <FIG>, core network <NUM> has Application and Mobility Management Function (AMF) <NUM>, with which anchor node <NUM> communicates (e.g., using an N2 interface). Core network <NUM> further has a bus <NUM> connecting various servers providing different example functionalities. For example, bus <NUM> can connect AMF <NUM> to Network Slice Selection Function (NSSF) <NUM>, Network Exposure Function (NEF) <NUM>, Network Repository Function (NRF) <NUM>, Unified Data Control (UDC) <NUM>, which itself can include example functions including Unified Data Management (UDM) <NUM>, Authentication Server Function (AUSF) <NUM>, Policy Control Function (PCF) <NUM>, Application Function (AF) <NUM> and Session Management Function (SMF) <NUM>. In one example, a node serving as SMF <NUM> may also function as a control plane Packet Gateway (PGW-C) node. Various components of core network <NUM>, examples of which are described above, provide known or to be developed functionalities for operation of <NUM> networks including, but not limited to, device registration, attachment and authentication, implementing network policies, billing policies, etc..

Furthermore, as shown in <FIG>, SMF <NUM> is connected to User Plane Function (UPF) <NUM>, which in turns connects core network <NUM> and/or UE <NUM> (after authentication and registration with core network <NUM>) to data network (DN) <NUM>. In one example, a node serving as UPF <NUM> may also function as a user plane Packet Gateway (PGW-C) node and/or a user plane Serving Gateway (SGW-U) node.

While <FIG> illustrates an example structure and components of core network <NUM>, the present disclosure is not limited thereto. Core network <NUM> can include any other number of known or to be developed logical functions and components and/or can have other known or to be developed architecture.

Furthermore, core network <NUM> can have a centralized Self Organizing Network (CSON) function/server <NUM> connected to AMF <NUM>. CSON server <NUM> can have a dedicated server for performing functionalities thereof, which will be described below, or can have functionalities thereof distributed among existing servers of core network <NUM>.

For purposes of illustration and discussion, network <NUM> has been described with reference to a limited number of UEs <NUM>, nodes <NUM>, <NUM>, <NUM>, <NUM>, etc. However, inventive concepts are not limited thereto.

Furthermore, while certain components have been illustrated and described with reference to <FIG>, network <NUM> can include any other known or to be developed elements or components for its operation.

As noted above, when UE <NUM> has an active session established with <NUM> core network <NUM>, a PDU session is created in core network <NUM> where a UPF node such as UPF <NUM> is selected by SMF <NUM> to forward and process data packets destined for or originating from UE <NUM>. In other words, UE <NUM> is connected to gNB (anchor node), AMF <NUM>, SMF <NUM>, UPF <NUM> and ultimately DN <NUM>.

<FIG> illustrates a handover process of a UE from a <NUM> network to a <NUM> network, according to one aspect of the present disclosure. <FIG> illustrates the interaction among several components some of which include UE <NUM>, gNB <NUM>, AMF <NUM>, PGW-C+SMF <NUM> (which will also be referred to as simply SMF <NUM>) and PGW-U+UPF <NUM> (which will also be referred to as simply UPF <NUM>) described above with reference to <FIG>. <FIG> illustrates a number of additional components such as Mobility Management Entity (MME) <NUM> and SGW-C <NUM>, both of which can form elements of LTE/<NUM> core <NUM> shown in <FIG>. <FIG> also illustrates a Domain Name System (DNS) server <NUM>, the use of which will be further described with reference to the handover process in <FIG>.

As noted above, a current active PDU session in <NUM> network <NUM> may exist for UE <NUM> shown as at S410 in <FIG>. Thereafter, a determination is made that UE <NUM> should be handed over from <NUM> network <NUM> to <NUM> network <NUM>. Such handover may be due to reasons including, but not limited to, better <NUM> coverage for UE <NUM>, offloading of traffic from <NUM> network to <NUM> network for load balancing, etc. Therefore, at S415, gNB <NUM> sends a Handover Required message to AMF <NUM> indicating a need to perform a <NUM> to <NUM> handover.

At S420, AMF <NUM> sends a message to SMF <NUM> (PGW-C+SMF <NUM>) to fetch Session Management (SM) context for the PDU session of S410. The message can be a Nsmf_PDUSession_ContextRequest message.

At S425, SMF <NUM> communicates with UPF <NUM> (SGW-U + UPF <NUM>) to obtain EPS bearer context for the PDU session as part of the requested SM context received at S420.

At S430, SMF <NUM> sends a response to the SM context back to AMF <NUM> as part of a Nsmf_PDUSession_ContextResponse message. As part of the response sent at S430, SMF <NUM> also sends a UPF node name of UPF <NUM> to the SMF <NUM>. UPF node name can be UPF <NUM>'s Fully Qualified Domain Name (FQDN), which can be sent in a custom Jason attribute back to AMF <NUM>.

At S435 and upon performing a MME selection in the <NUM> plane of <NUM> network <NUM> (according to any known or to be developed method of MME selection, which in one example can result in MME <NUM> being selected), AMF <NUM> forwards the SM context received from SMF <NUM> along with the UPF node Name is a custom attribute of a Relocation Request message to MME <NUM>.

At S440 and upon performing a SGW-C selection in the <NUM> plane of <NUM> network <NUM> (according to any known or to be developed method of SGW-C selection, which in one example can result in SGW-C <NUM> being selected), MME <NUM> forwards SM context along with the UPF Node Name to SGW-C <NUM> in a custom attribute of a Create Session Request message.

At S445, SGW-C <NUM> initiates SGW-U selection by sending a Name Authority Pointer (NAPTR) query to DNS <NUM> to fetch all possible SGW-U candidates to SGW-C <NUM>. In one example such candidates can include SGW-U <NUM>, <NUM> and <NUM> shown in <FIG> and <FIG>.

At S450, DNS <NUM> responds by providing all candidate nodes along with their corresponding FQDN and service parameters. In one example, a service provider of <NUM> network <NUM> can configure a new service parameter for all SGW-U nodes that support Sxa and N4 services. Such service parameter can have the format "x-3gpp-upf:x-sxa+n4.

At S455, SGW-C <NUM> selects one of the SGW-U candidates received from DNS <NUM> by performing a topology match using the service parameter described above and the UPF Node Name of UPF <NUM> received at S430. The process at S445, ensures that SGW-C <NUM> selects, from among all SGW-U candidates (e.g., SGW-U <NUM>, <NUM> and <NUM>), the same PGW-U+UPF node <NUM> that served as the PDU node (peer N4 node) of UE <NUM> while UE <NUM> was active on <NUM> network <NUM>, as the new SGW-U node for UE <NUM> in the <NUM> network <NUM>, making the selected SGW-U and PGW-U+UPF nodes co-located. The co-location can be ensured by performing a topology match between candidate FQDNs received at S450 from DNS <NUM> and FQDN received as part of the SM Context at S440.

Thereafter, at S460, SGW-C <NUM> initiates Sx Session Establishment Request toward the selected SGW-U (which is the same as SGW-C + UPF <NUM>) for setting up sxa related Packet Detection Rule (PDR) and Forwarding Action Rules (FARs).

At S460, selected SGW-U node accepts the parameters in Sx Session Establishment Response message and sends a response back to SGW-C <NUM>.

At S465, SGW-C <NUM> sends a Create Session Response message back to MME <NUM> in response to the Create Session Request received at S440.

Thereafter, at S470, the remaining handover steps for a <NUM> to <NUM> handover, as specified in <NUM>rd Generation Partnership Project (3GPP) specification <NUM> can be implemented to complete the <NUM> to <NUM> handover of UE <NUM>.

The process of <FIG> achieves a reduction in number of hops when UE <NUM> communicates with DN <NUM> after a handover, which will be described below.

While <FIG> has been described with reference to a specific example of a <NUM> to <NUM> handover of a UE, the present disclosure is not limited thereto and the process can be applied equally for a <NUM> to <NUM> handover to ensure selection of the same <NUM> SGW-U node as the PGW-U+UPF node in the <NUM> network.

<FIG> illustrates an example three-hop communication process for a UE after performing handover process of <FIG>, according to one aspect of the present disclosure.

In describing the state of the art with respect to <FIG> and <FIG> above, it was noted that because the selection of the same <NUM> UPF node as the new SGW-U node in the <NUM> network is not guaranteed currently, the resulting communication between UE <NUM> and DN <NUM> is a four-hop process (D1-> D2-> D3-> D4). <FIG> illustrates the efficiency gained and hence the reduction of the four-hop process to a three-hop process because the selection of the <NUM> UPF as the SGW-U node in the <NUM> network is guaranteed.

As shown in <FIG> and using same reference numerals as <FIG> and <FIG> for purposes of illustrating differences, a data path between UE <NUM> (Same as UE <NUM>) and DN <NUM> now includes D1 (from UE <NUM> to eNodeB <NUM>), D2 (from eNodeB <NUM> to SGW-U / PGW-U+UPF <NUM> (which can be the same as SGW-U / PGW-U+UPF <NUM> of <FIG>) and D3 (from SGW-U / PGW-U+UPF <NUM> to DN <NUM>).

This three step process can reduce latency in data paths that can be critical to low latency requirement of <NUM> applications.

Having described example embodiments for ensuring optimized selection of SGW-U after a <NUM> to <NUM> handover (or PGW-U+ UPF after a <NUM> to <NUM> handover), the disclosure now turns to discussion of example devices that can be used as components within <NUM> network <NUM> and/or <NUM> network <NUM> as various nodes thereof (e.g., SGW-C <NUM>, SMF <NUM>, UPF <NUM>, MME <NUM>, AMF <NUM>, etc.) or a controller controlling functionalities of each node of such network to implement the handover processes described above.

<FIG> illustrates an example system including various hardware computing components, according to an aspect of the present disclosure. The more appropriate embodiment will be apparent to those of ordinary skill in the art when practicing the present technology. Persons of ordinary skill in the art will also readily appreciate that other system embodiments are possible.

<FIG> illustrates a system bus computing system architecture (system) <NUM> wherein the components of the system are in electrical communication with each other using a connection <NUM>. Exemplary system <NUM> includes a cache <NUM> and a processing unit (CPU or processor) <NUM> and a system connection <NUM> that couples various system components including the system memory <NUM>, such as read only memory (ROM) <NUM> and random access memory (RAM) <NUM>, to the processor <NUM>. System <NUM> can include a cache of highspeed memory connected directly with, in close proximity to, or integrated as part of the processor <NUM>. System <NUM> can copy data from the memory <NUM> and/or the storage device <NUM> to the cache <NUM> for quick access by the processor <NUM>. In this way, the cache can provide a performance boost that avoids processor <NUM> delays while waiting for data. These and other modules can control or be configured to control the processor <NUM> to perform various actions. Other system memory <NUM> may be available for use as well. The memory <NUM> can include multiple different types of memory with different performance characteristics. The processor <NUM> can include any general purpose processor and a service component, such as service <NUM><NUM>, service <NUM><NUM>, and service <NUM><NUM> stored in storage device <NUM>, configured to control the processor <NUM> as well as a special-purpose processor where software instructions are incorporated into the actual processor design. The processor <NUM> may essentially be a completely self-contained computing system, containing multiple cores or processors, a bus, memory controller, cache, etc. A multi-core processor may be symmetric or asymmetric.

To enable user interaction with system <NUM>, an input device <NUM> can represent any number of input mechanisms, such as a microphone for speech, a touch-sensitive screen for gesture or graphical input, keyboard, mouse, motion input, speech and so forth. An output device <NUM> can also be one or more of a number of output mechanisms known to those of skill in the art. In some instances, multimodal systems can enable a user to provide multiple types of input to communicate with system <NUM>. The communications interface <NUM> can generally govern and manage the user input and system output. There is no restriction on operating on any particular hardware arrangement and therefore the basic features here may easily be substituted for improved hardware or firmware arrangements as they are developed.

System <NUM> can include an integrated circuit <NUM>, such as an application-specific integrated circuit (ASIC) configured to perform various operations. The integrated circuit <NUM> can be coupled with the connection <NUM> in order to communicate with other components in system <NUM>.

The storage device <NUM> can include software services <NUM>, <NUM>, <NUM> for controlling the processor <NUM>. Other hardware or software modules are contemplated. The storage device <NUM> can be connected to the system connection <NUM>. In one aspect, a hardware module that performs a particular function can include the software component stored in a computer-readable medium in connection with the necessary hardware components, such as the processor <NUM>, connection <NUM>, output device <NUM>, and so forth, to carry out the function.

In some example embodiments the computer-readable storage devices, mediums, and memories can include a cable or wireless signal containing a bit stream and the like.

Claim 1:
A method comprising:
receiving, at a network component, a session creation request (S440) for handing over a user equipment (<NUM>) from a <NUM> communication network to a <NUM> communication network, the network component being included in the <NUM> communication network, the user equipment (<NUM>) having a current active communication session within the <NUM> communication network with a first node (<NUM>) of the <NUM> communication network acting as a User Plane Function, UPF, node of the user equipment (<NUM>), the session creation request including an identifier of the first node (<NUM>);
querying (S445), by the network component, a Domain Name Server, DNS, (<NUM>) for a list of candidates, each candidate having a corresponding service parameter indicating whether the corresponding candidate supports N4 and Sxa services;
receiving (S450), at the network component, the list of candidates to serve as a user plane serving gateway for the user equipment (<NUM>) in the <NUM> communication network along with the corresponding service parameters, the list of candidates including the first node (<NUM>);
selecting (S455), by the network component and based on at least the identifier of the first node (<NUM>) and on performing a topology match using the corresponding service parameters of the candidates, the first node (<NUM>) from the list of candidates to serve as the user plane serving gateway for the user equipment (<NUM>) in the <NUM> communication network; and
establishing, by the network component, a new session for the user equipment (<NUM>) in the <NUM> communication network using the first node (<NUM>) as the user plane serving gateway for the user equipment (<NUM>) in the <NUM> communication network.