Patent Application
20220151004
The present disclosure relates to Protocol Data Unit (PDU) session establishment in a cellular communications system.
The Third Generation Partnership Project (3GPP) Technical Specification (TS) 23.502 provides a procedure for user equipment (UE)-requested Protocol Data Unit (PDU) Session Establishment for non-roaming and roaming with local breakout. The baseline procedure shown below in table 1 and illustrated in
The 3GPP Specification Group on Service and Systems Aspects, Architecture Subgroup (SA2) agreed in document S2-1901089 that the operations in step 13 above provide that the DL NAS transport carrying the PDU session establishment accept message is not sent by the 5G access network to the UE if the 5G access network cannot allocate radio resources needed for the PDU session. Consequently, if the DL NAS transport carrying the PDU session establishment accept message is not sent to the UE, according to TS 24.501 subclause 6.4.1.6 bullet (a), upon expiration of timer T3580, the UE will retransmit a PDU session establishment request message and transport it using an UL NAS transport to the AMF. Subsequently, according to TS 24.501 subclause 5.4.5.2.5 bullet (a)(12), upon reception of the UL NAS transport with the retransmitted PDU session establishment request message from the UE, the AMF performs a local release of the existing PDU session and requests the SMF perform a local release of the existing PDU session, after which the AMF performs a new SMF selection and forwards the retransmitted PDU session establishment request message to a new SMF. If the new SMF attempts to set up the PDU session with resources which the 5G access network is again unable to allocate, and the 5G access network does not send the DL NAS transport carrying the PDU session establishment accept message to the UE again, the process described in the above paragraph will repeat five (5) times.
However, there currently exist certain challenge(s). As noted above, if the 5G access network does not send the DL NAS transport carrying PDU session establishment accept message to the UE, the process described above will repeat five (5) times, which may generate an excessive number of unnecessary 5G session management (SM) messages sent over the radio and may further result in unnecessary network actions (e.g., the AMF will select an SMF, the SMF will attempt to establish a PDU session, the AMF and the SMF will locally release the PDU session, and so forth, all repeated up to five (5) times).
Systems and methods for avoiding transmission of unnecessary 5G session management (SM) messages are disclosed herein. Embodiments of a method performed in a core network of a cellular communications system to avoid transmission of unnecessary SM messages are disclosed. In some embodiments, the method comprises, at a radio access network (RAN), determining that a non-access stratum (NAS) message carrying a Protocol Data Unit (PDU) session establishment accept indication was not sent to a user equipment (UE). The method further comprises sending, to an Access and Mobility Management Function (AMF), an N2 PDU session request acknowledgment indication comprising a cause indicating that the NAS message carrying the PDU session establishment accept indication was not sent to the UE. The method also comprises, at the AMF, receiving, from the RAN, the N2 PDU session request acknowledgment indication comprising the cause. The method additionally comprises sending an Nsmf_PDUSession_UpdateSMContext request comprising the cause to a Session Management Function (SME). The method further comprises, at the SMF, determining that the NAS message carrying the PDU session establishment accept indication was not sent to the UE by the RAN. The method also comprises, responsive to determining that the NAS message carrying the PDU session establishment accept indication was not sent to the UE, sending a PDU session establishment reject indication to the UE.
Embodiments of a method performed by an SMF in a core network of a cellular communications system to avoid transmission of unnecessary SM messages are disclosed. In some embodiments, the method comprises determining that an NAS message carrying a PDU session establishment accept indication was not sent to a UE by a RAN. The method further comprises, responsive to determining that the NAS message carrying the PDU session establishment accept indication was not sent to the UE, sending a PDU session establishment reject indication to the UE. In some embodiments, determining that the NAS message carrying the PDU session establishment accept indication was not sent to the UE comprises receiving, from an AMF, an Nsmf_PDUSession_UpdateSMContext request comprising a cause, and determining that the NAS message carrying the PDU session establishment accept indication was not sent to the UE based on the cause. In some embodiments, sending the PDU session establishment reject indication to the UE comprises sending an Namf_Communication_N1N2MessageTransfer comprising the PDU session establishment reject indication to the AMF.
Embodiments of an SMF for a core network of a cellular communications system enabled to avoid transmission of unnecessary SM messages are disclosed. In some embodiments, the SMF is adapted to determine that an NAS message carrying a PDU session establishment accept indication was not sent to a UE by a radio access network. The SMF is further adapted to send a PDU session establishment reject indication to the UE responsive to determining that the NAS message carrying the PDU session establishment accept indication was not sent to the UE. In some embodiments, the SMF is further adapted to perform any of the steps attributed to the SMF in any of the above-disclosed methods.
Embodiments of a network node for implementing an SMF for a core network of a cellular communications system, where the SMF is enabled to avoid transmission of unnecessary SM messages, are disclosed. In some embodiments, the network node comprises a network interface, and processing circuitry associated with the network interface. The processing circuitry is adapted to cause the network node to implement the SMF such that the SMF is configured to determine that an NAS message carrying a PDU session establishment accept indication was not sent to a UE by a radio access network. The processing circuitry is further adapted to cause the network node to implement the SMF such that the SMF is further configured to send a PDU session establishment reject indication to the UE, responsive to determining that the NAS message carrying the PDU session establishment accept indication was not sent to the UE. In some embodiments, the processing circuitry is adapted to cause the network node to implement the SMF such that the SMF is further configured to perform any of the steps attributed to the SMF in any of the above-disclosed methods.
Embodiments of a method performed by a RAN in a core network of a cellular communications system to avoid transmission of unnecessary SM messages are disclosed. In some embodiments, the method comprises determining that an NAS message carrying a PDU session establishment accept indication was not sent to a UE. The method further comprises sending, to an AMF, an N2 PDU session request acknowledgment indication comprising a cause indicating that the NAS message carrying the PDU session establishment accept indication was not sent to the UE. In some embodiments, the method also comprises receiving a PDU session establishment reject indication from the AMF. The method additionally comprises sending the PDU session establishment reject indication to the UE using access network signaling.
Embodiments of a RAN for a core network of a cellular communications system enabled to avoid transmission of unnecessary SM messages are disclosed. In some embodiments, the RAN is adapted to determine that an NAS message carrying a PDU session establishment accept indication was not sent to a UE. The RAN is further adapted to send, to an AMF, an N2 PDU session request acknowledgment indication comprising a cause indicating that the NAS message carrying the PDU session establishment accept indication was not sent to the UE. In some embodiments, the RAN is further adapted to perform any of the steps attributed to the RAN in any of the above-disclosed methods.
Embodiments of a network node for implementing a RAN for a core network of a cellular communications system where the RAN is enabled to avoid transmission of unnecessary SM messages are disclosed. In some embodiments, the network node comprises a network interface, and processing circuitry associated with the network interface. The processing circuitry is adapted to cause the network node to implement the RAN such that the RAN is configured to determine that an NAS message carrying a PDU session establishment accept indication was not sent to a UE. The processing circuitry is further adapted to cause the network node to implement the RAN such that the RAN is further configured to send, to an AMF, an N2 PDU session request acknowledgment indication comprising a cause indicating that the NAS message carrying the PDU session establishment accept indication was not sent to the UE. In some embodiments, the processing circuitry is further adapted to cause the network node to implement the RAN such that the RAN is further configured to perform any of the steps attributed to the RAN in any of the above-disclosed methods.
The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.
The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.
Radio Node: As used herein, a “radio node” is either a radio access node or a wireless device.
Radio Access Node: As used herein, a “radio access node” or “radio network node” is any node in a radio access network of a cellular communications system 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 pica base station, a home eNB, or the like), and a relay node.
Core Network Entity: As used herein, a “core network entity” is any type of entity in a core network. Some examples of a core network entity include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), or the like in an Evolved Packet Core (EPC). Some other examples of a core network entity include, e.g., an Access and Mobility Management Function (AMF), a Network Slice Selection Function (NSSF), an Authentication Server Function (AUSF), a UDM, a Session Management Function (SMF), a Policy Control Function (PCF), an AF, a NEF, a User Plane Function (UPF), or the like in a 5G Core (5GC). A core network entity may be implemented as a physical network node (e.g., including hardware or a combination of hardware and software) or implemented as a functional entity (e.g., as software) that is, e.g., implemented on a physical network node or distributed across two or more physical network nodes.
Wireless Device: As used herein, a “wireless device” is any type of device that has access to (i.e., is served by) a cellular communications system by wirelessly transmitting and/or receiving signals to a radio access node(s). Some examples of a wireless device include, but are not limited to, a User Equipment device (UE) in a 3GPP network and a Machine Type Communication (MTC) device.
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.
Systems and methods for avoiding transmission of unnecessary 5GSM messages are disclosed herein.
In this regard,
The base stations 202 and the low power nodes 206 provide service to wireless devices 212-1 through 212-5 in the corresponding cells 204 and 208. The wireless devices 212-1 through 212-5 are generally referred to herein collectively as wireless devices 212 and individually as wireless device 212. The wireless devices 212 are also sometimes referred to herein as UEs.
Reference point representations of the 5G network architecture are used to develop detailed call flows in the normative standardization. The N1 reference point is defined to carry signaling between the UE 212 and AMF 302. The reference points for connecting between the RAN 300 and the AMF 302 and between the RAN 300 and the UPF 316 are defined as N2 and N3, respectively. There is a reference point, N11, between the AMF 302 and the SMF 310, which implies that the SMF 310 is at least partly controlled by the AMF 302. N4 is used by the SMF 310 and the UPF 316 so that the UPF 316 can be set using the control signal generated by the SMF 310, and the UPF 316 can report its state to the SMF 310. N9 is the reference point for the connection between different UPFs 316, and N14 is the reference point connecting between different AMFs 302, respectively. N15 and N7 are defined since the PCF 312 applies policy to the AMF 302 and the SMF 310, respectively. N12 is required for the AMF 302 to perform authentication of the UE 212. N8 and N10 are defined because the subscription data of the UE 212 is required for the AMF 302 and the SMF 310.
The 5G core network aims at separating user plane and control plane. The user plane carries user traffic while the control plane carries signaling in the network. In
The core 5G network architecture is composed of modularized functions. For example, the AMF 302 and the SMF 310 are independent functions in the control plane. Separated AMFs 302 and SMFs 310 allow independent evolution and scaling. Other control plane functions like the PCF 312 and the AUSF 306 can be separated as shown in
Each NF interacts with another NF directly. It is possible to use intermediate functions to route messages from one NF to another NF. In the control plane, a set of interactions between two NFs is defined as service so that its reuse is possible. This service enables support for modularity. The user plane supports interactions such as forwarding operations between different UPFs 316.
Some properties of the NFs shown in
An NF may be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure.
The steps of
At step 532, the SMF 310 determines (e.g., based on the Cause provided by the AMF at step 15) that the NAS message carrying the PDU session establishment accept message was not sent to the UE 212 by the 5G access network, and consequently initiates the release of the PDU session. The SMF 310 at step 534 sends a Nsmf_PDUSession_UpdateSMContext response to the AMF 302. Subsequently, at step 536, the SMF 310 determines that the NAS message carrying the PDU session establishment accept indication was not sent to the UE 212, and sends a PDU session establishment reject message using a Namf_Communication_N1N2MessageTransfer to the AMF 302. In some embodiments, the PDU session establishment reject message includes the 5GSM cause value #26 “insufficient resources,” the 5GSM cause value #69 “insufficient resources for specific slice,” or the 5GSM cause value #67 “insufficient resources for specific slice and DNN” as the 5GSM cause. The AMF 302 then sends the PDU session establishment reject message via an N2 downlink NAS transport request to the RAN 300 at step 538, which then uses access network signaling to send the PDU session establishment reject message to the UE 212 at step 540. The UE 212 then releases the PDU session at step 542.
As used herein, a “virtualized” network node is an implementation of the network node 600 in which at least a portion of the functionality of the network node 600 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)). As illustrated, in this example, the network node 600 includes one or more processing nodes 700 coupled to or included as part of a network(s) 702. Each processing node 700 includes one or more processors 704 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 706, and a network interface 708.
In this example, function(s) 710 of the network node 600 described herein (e.g., the function(s) of a core network entity such as, e.g., an AMF, V-SMF, V-UPF, H-SMF, H-UPF, UDM, or NEF) are implemented at the one or more processing nodes 700 in any desired manner. In some particular embodiments, some or all of the function(s) 710 of the network node 600 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) 700.
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 entity (e.g., an AMF, V-SMF, V-UPF, H-SMF, H-UPF, UDM, or NEF) as 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).
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 the UE 900 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.
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.).
While not being limited thereto, some example embodiments of the present disclosure are provided below.
A method performed in a core network of a cellular communications system to avoid transmission of unnecessary session management, SM, messages, the method comprising:
A method performed by a Session Management Function, SMF, (310) in a core network (210) of a cellular communications system (200) to avoid transmission of unnecessary session management, SM, messages, the method comprising:
The method of embodiment 2, wherein determining that the NAS message carrying the PDU session establishment accept indication was not sent to the UE (212) comprises:
The method of embodiment 2, wherein sending (536) the PDU session establishment reject indication to the UE (212) comprises sending (536) an Namf_Communication_N1N2MessageTransfer comprising the PDU session establishment reject indication to the AMF (302).
A Session Management Function, SMF, (310) for a core network (210) of a cellular communications system (200) enabled to avoid transmission of unnecessary session management, SM, messages, the SMF (310) adapted to:
The SMF (310) of embodiment 5 wherein the SMF (310) is further adapted to perform the method of any one of embodiments 3 to 4.
A network node (600) for implementing a Session Management Function, SMF, (310) for a core network (210) of a cellular communications system (200) where the SMF (310) is enabled to avoid transmission of unnecessary session management, SM, messages, the network node (600) comprising:
The network node (600) of embodiment 7 wherein the processing circuitry (604) is adapted to cause the network node (600) to implement the SMF (310) such that the SMF (310) is further configured to perform the method of any one of embodiments 3 to 4.
A method performed by a radio access network, RAN, (300) in a core network (210) of a cellular communications system (200) to avoid transmission of unnecessary session management, SM, messages, the method comprising:
The method of embodiment 9, further comprising:
A radio access network, RAN, (300) for a core network (210) of a cellular communications system (200) enabled to avoid transmission of unnecessary session management, SM, messages, the RAN (300) adapted to:
The RAN (300) of embodiment 11 wherein the RAN (300) is further adapted to perform the method of embodiment 9.
A network node (600) for implementing a radio access network, RAN, (300) for a core network (210) of a cellular communications system (200) where the RAN (300) is enabled to avoid transmission of unnecessary session management, SM, messages, the network node (600) comprising:
The network node (600) of embodiment 13 wherein the processing circuitry (604) is adapted to cause the network node (600) to implement the RAN (300) such that the RAN (300) is further configured to perform the method of embodiment 9.
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).
Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.
This application claims the benefit of provisional patent application Ser. No. 62/807,078, filed Feb. 18, 2019, the disclosure of which is hereby incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2020/051342 | 2/18/2020 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62807078 | Feb 2019 | US |
