Patent Application
20230164652
Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and/or is implied from the context in which it is used. All references to a/an/the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and/or where it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features, and advantages of the enclosed embodiments will be apparent from the following description.
Interworking between the Evolved Packet Core (EPC) of 4G and the 5G Core (5GC) requires the selection of a Session Management Function (SMF)/Packet Data Network Gateway-Control Plane (PGW-C) (which may be implemented as a combined SMF/PGW-C network function) together with a User Plane Function (UPF)/Packet Data Network Gateway-User Plane (PGW-U) (which may be implemented as a combined UPF/PGW-U network function). This is vital to maintain session continuity when the User Equipment (UE) moves between a 4G radio access network and a 5G radio access network (see, e.g., 3rd Generation Partnership Project (3GPP) Technical Specification (TS) 23.501 ch. 5.17.2; TS 23.502 ch. 4.11; TS 29.303 ch.
5.12.3).
A UE may attempt to access services available over a 5GC radio access via 5G radio access (i.e., over a 5G/NR radio access network (RAN)), or by accessing the 5GC through a 4G radio access (i.e., via a 4G/LTE RAN).
An alternative situation is illustrated in
To initiate UE access to a network slice of the 5GC via 4G radio access, as illustrated in
The following tables shows some key parameters for a combined SMF/PGW-C in its Network Function (NF) profile stored in the NF Repository Function (NRF), where the SMF is configured to support an array of network slices (Network Slice Selection Assistance Information (NSSAI)), and each network slice is configured with a number of supported Data Network Names (i.e. Access Point Names (APNs) for 4G/3G/2G network). Note that the NSSAI is a collection of S-NSSAIs. An S-NSSAI identifies a network slice.
During an Evolved Packet System (EPS) to 5G System (5GS) mobility procedure (i.e., EPC to 5GC), the PGW Node Name is transferred from the Source MME to the target AMF when an N26 interface is available, or the target AMF receives the PGW Node Name from the Unified Data Management (UDM)/Home Subscriber Server (HSS) when an N26 interface is not available.
As an example, in TS 23.502, 4.11.1.2.2, step 4 (for the case in which N26 is available):
As another example, in TS 23.502, 4.11.2.3 EPS to 5GS Mobility, step 9:
This is also reflected in stage 3 specification e.g. in TS 29.274, the Forward Relocation Request message is used for connected mode mobility procedure.
And the Context Response message is used for Idle mode mobility procedure.
There currently exist certain challenge(s). In general, the MME does not have sufficient information (i.e. no network slice information, which is part of 5G subscription information) to select an SMF/PGW-C supporting the correct network slice.
The key parameter used by the MME to select a PGW is the Access Point Name (APN), which may be used across a number of network slices, i.e. multiple network slices may support access to the same Data network (identified by the APN). However, the PGW may be configured to support only a subset of network slices for a given APN, and the UE may have a subscription only allowing access to specific network slices for that APN. In other words, the APN may be used across a number of network slices, where only some of those network slices may be supported by the selected PGW, and the UE may have a subscription to a network slice that is not supported by the selected PGW.
In short, the PGW selected by the MME may not be able to accept a request for creation of a session for the PDN connection if the PGW is not configured to support the network slice that the UE subscription allows among the network slices for the requested APN.
The standard does not specify any requirement when the above scenario takes place. One approach is certainly to reject the request, however such rejection results in a very bad Key Performance Indicator (KPI) and, when the UE tries again to establish the PDN connection, the request may be rejected again.
Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges.
There are, proposed herein, various embodiments which address one or more of the issues disclosed herein.
In some embodiments, a method for interworking between a 4G EPC and a 5G EPC in a network node is disclosed. In some embodiments, a method of operation of a first network node (e.g., a first SMF/PGW-C) comprises receiving a request to create a session for a UE for a particular APN/DNN and determining that the first network node is not configured to support a subscribed network slice of the UE that contains the particular APN/DNN. In some embodiments, the method further comprises identifying a second network node (e.g., PGW2 or second SMF/PGW-C) that is configured to support the subscribed network slice of the UE that contains the particular APN/DNN and transferring the request to create a session for the UE for the particular APN/DNN.
In some embodiments, a method of operation of a first network node (e.g., a first SMF/PGW-C) comprises receiving a request to create a session for a UE for a particular APN/DNN and determining that the first network node is not configured to support a subscribed network slice of the UE that contains the particular APN/DNN. In some embodiments, the method further comprises identifying a second network node (e.g., PGW2 or second SMF/PGW-C) that is configured to support the subscribed network slice of the UE that contains the particular APN/DNN, and sending a response to the request, the response comprising information that indicates the second network node.
In some embodiments, a method of operation of a first network node comprises sending to a second network node (e.g., SMF/PGW-C #1), a request to create a session for a UE for a particular APN/DNN, and receiving, from a third network node (e.g., SMF/PGW-C #2), a response to the request.
In some embodiments, a method includes a first network node sending, to a second network node (e.g., SMF/PGW-C #1), a request to create a session for a UE for a particular APN/DNN, receiving, from the second network node, a response to the request, the response comprising information that indicates a third network node (e.g., SMF/PGW-C #2), and sending the request to the third network node.
In some embodiments, method includes a second network node receiving, from a first network node (e.g., SMF/PGW-C #2), a request to create a session for a UE for a particular APN/DNN, the request comprising information that enables or otherwise causes the second network node to send the response to an originating node of the request wherein the originating node is a node from which the first network node received the request, and sending, to the originating node, a response to the request.
Certain embodiments may provide one or more of the following technical advantage(s). The proposed solution significantly increases the probability that session continuity can be maintained within the correct Network Slice when the UE first attaches to E-UTRAN and then moves into 5G access.
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in a constitute a part of this application, illustrate certain non-limiting embodiments of inventive concepts. In the drawings:
Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art. Additional information may also be found in the document(s) provided in the Appendix.
Radio Node: As used herein, a “radio node” is either a radio access node or a wireless communication device.
Radio Access Node: As used herein, a “radio access node” or “radio network node” or “radio access network node” is any node in a Radio Access Network (RAN) of a cellular communications network that operates to wirelessly transmit and/or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), a relay node, a network node that implements part of the functionality of a base station (e.g., a network node that implements a gNB Central Unit (gNB-CU) or a network node that implements a gNB Distributed Unit (gNB-DU)) or a network node that implements part of the functionality of some other type of radio access node.
Core Network Node: As used herein, a “core network node” is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing a Access and Mobility Function (AMF), a UPF, a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.
Communication Device: As used herein, a “communication device” is any type of device that has access to an access network. Some examples of a communication device include, but are not limited to: mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or Personal Computer (PC). The communication device may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data via a wireless or wireline connection.
Wireless Communication Device: One type of communication device is a wireless communication device, which may be any type of wireless device that has access to (i.e., is served by) a wireless network (e.g., a cellular network). Some examples of a wireless communication device include, but are not limited to: a User Equipment device (UE) in a 3GPP network, a Machine Type Communication (MTC) device, and an Internet of Things (IoT) device. Such wireless communication devices may be, or may be integrated into, a mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or PC. The wireless communication device may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data via a wireless connection.
Network Node: As used herein, a “network node” is any node that is either part of the radio access network or the core network of a cellular communications network/system.
Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system.
Note that, in the description herein, reference may be made to the term “cell”; however, particularly with respect to 5G NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.
The base stations QQ102 and the low power nodes QQ106 provide service to wireless communication devices QQ112-1 through QQ112-5 in the corresponding cells QQ104 and QQ108. The wireless communication devices QQ112-1 through QQ112-5 are generally referred to herein collectively as wireless communication devices QQ112 and individually as wireless communication device QQ112. In the following description, the wireless communication devices QQ112 are oftentimes UEs, but the present disclosure is not limited thereto.
For interworking between EPC (4G) and 5GC, when an SMF/PGW-C is selected by the MME and the PGW-C/SMF receives the Create Session Request, the SMF/PGW-C will retrieve Session Management Subscription data from the UDM as specified in 5.2.2.2.5 Session Management Subscription Data Retrieval. Among other things, the Create Session Request includes information that indicates the requested APN/DNN, and the subscription data of the UE includes the subscribed S-NSSAI that contains the requested APN/DNN (information that indicates the subscribed network slice that contains the requested APN/DNN). Using this information, the SMF/PGW-C determines whether it is configured to support the subscribed S-NSSAI that contains the requested APN/DNN. In other words, the SMF/PGW-C determines whether it is able to (or configured to) support the subscribed network slice that uses the requested APN/DNN. If the SMF/PGW-C determines that it is not configured to support the subscribed S-NSSAI which contains the requested APN/DNN, the SMF/PGW-C signals to the NRF to perform a service discovery procedure, to find a SMF/PGW-C that does support a session on the UE subscribed S-NSSAI that contains the particular APN/DNN.
After that, there are two alternative approaches, each of which are described below in detail. In general, in the first alternative (Alternative 1), the SMF/PGW-C redirects the Create Session Request message to the SMF/PGW-C, found via the NRF discovery procedure, that does support the subscribed S-NSSAI and the requested APN. In the second alternative (Alternative 2), the SMF/PGW-C sends a Create Session Response message that includes information that indicates the new SMF/PGW-C that does support the subscribed S-NSSAI and the requested APN.
In this alternative, after the MME selected SMF/PGW-C receives the information from the NRF, the SMF/PGW-C redirects the Create Session Request message to the new SMF/PGW-C. One example procedure that illustrates this alternative is illustrated in
In another aspect, after the SMF/PGW-C signals to the NRF to perform a service discovery procedure to find a SMF/PGW-C that does support the subscribed S-NSSAI and the APN for the PDN connection, a second alternative can be used in which information that indicates SMF/PGW-C #2 is returned in the Create Session Response message.
Note that, in Alternative 2, the new SMF/PGW-C(SMF/PGW-C #2) includes its Fully Qualified Domain Name (FQDN) in the Create Session Response, and this information is utilized by the MME. Note that:
The problem being addressed and aspects of the disclosed solution(s) can be summarized as follows:
As used herein, a “virtualized” core network node is an implementation of the core network node QQ200 in which at least a portion of the functionality of the core network node QQ200 is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). The core network node QQ200 includes one or more processing nodes QQ300 each coupled to or included as part of a network(s) QQ302. If present, the control system QQ202 is connected to the processing node(s) QQ300 via the network QQ302. Each processing node QQ300 includes one or more processors QQ304 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory QQ306, and a network interface QQ308.
In this example, functions QQ310 of the core network node QQ200 described herein (e.g., functions of a an EPC node, a 5GC NF, or a combined network function (e.g., SMF/PGG-C) according to any of the embodiments described herein, e.g., with respect to
In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of a core network node QQ200 or a node (e.g., a processing node QQ300) implementing one or more of the functions QQ310 of the core network node QQ200 in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).
Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according one or more embodiments of the present disclosure.
While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).
Some of the embodiments are described above can be summarized in the following manner:
1. A method performed by a first network node (e.g., SMF/PGW-C #1) for interworking between a 4G Evolved Packet Network (EPC) and a 5G core (5GC), the method comprising:
At least some of the following abbreviations may be used in this disclosure. If there is an inconsistency between abbreviations, preference should be given to how it is used above. If listed multiple times below, the first listing should be preferred over any subsequent listing(s).
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/053283 | 2/11/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62976157 | Feb 2020 | US |
