Standalone user plane function for replication and elimination function

Abstract

According to one aspect, a method in a session management function (SMF) network node is described. The method includes determining that at least one of a first packet data unit (PDU) session and a second PDU session is associated with a redundant traffic handling of data packets associated with at least one user equipment (UE). The method also includes selecting the first UPF network node to perform the redundant traffic handling of data packets associated with the at least one UE, the first PDU session, and the second PDU session based on the determination. The redundant traffic handling is performed using a first PREOF, a first tunnel associated with the first PDU session and a second tunnel associated with the second PDU session. The method also includes causing the first UPF network node to perform the redundant traffic handling.

Description

[0001] STANDALONE USER PLANE FUNCTION FOR REPLICATION AND

[0002] ELIMINATION FUNCTION

[0003] TECHNICAL FIELD

[0004] The present disclosure relates to wireless communications, and in particular, to configuration and use of a standalone user plane function (UPF) for replication and elimination of communication packets.

[0005] BACKGROUND

[0006] The Third Generation Partnership Project (3 GPP) has developed and is developing standards for Fourth Generation (4G) (also referred to as Long Term Evolution (LTE)) and Fifth Generation (5G) (also referred to as New Radio (NR)) wireless communication systems. Such systems provide, among other features, broadband communication between network nodes (NNs), such as base stations, and user equipment (UE), as well as communication between network nodes and between UEs. The 3GPP is also developing standards for Sixth Generation (6G) wireless communication networks.

[0007] A 3GPP network may provide mechanisms for redundant transmission of traffic flows within the 3 GPP system, where two (or more) copies of data packets are sent and delivered through separate paths, where the paths may be disjoint to the maximum extent possible at a given deployment. On the receiving side, the duplicate data packets may be eliminated, and only a single copy may be delivered. The redundant traffic handling allows hiding the effect of any error on one transmission path without losses. Hence, the use of redundancy mechanisms may increase the availability of the communication system. In certain cases, the 3 GPP network may provide the full redundancy solution, while in other cases the 3GPP network may provide some of the mechanisms for redundancy which are used in combination with other mechanisms defined by other industry or standardization fora, so that in combination a full solution is provided.

[0008] Packet data convergence protocol (PDCP) duplication (e.g., as described in 3GPP Technical Specification (TS) 38.300 V17.7.0, section 16.1.3) may be used within a radio access network (RAN) to send the same packet over multiple data bearers. Using PDCP duplication, duplicate copies of the same packet may be transmitted via different RAN nodes using dual connectivity (DC), so that the receiving PDCP entity eliminates the duplicate copies. The use of PDCP duplication can be configured into the RAN and can be used based on 5G quality of service (QoS) identifier (5QI) values. QoS Flow ID (QFI) carried in the packet header may determine the 5QI of the given packet flow.

[0009] Further, support for redundant transmission on interfaces such as N3 / N9 interfaces is defined in 3GPP TS 23.501 V17.9.0, section 5.33.2.2. A session management function (SMF) may configure two redundant general packet radio services (GPRS) tunnelling protocol (GTP) tunnels between the RAN node and a protocol data unit (PDU) session anchor (PSA) user plane function (UPF). The packets are duplicated and transmitted with the same GTP user plane (GTP-U) sequence number, which is used by the receiving side to eliminate the duplicated transmissions. The use of the redundant transmission can be applied on a per flow basis based on the SMF’s configuration. Redundant data transmission on the N3 / N9 is also possible using redundancy mechanisms in the transport layer, e.g., as described in 3GPP TS 23.501 V17.9.0, section 5.33.2.3. In this case, the redundancy mechanism is used in the transport layer to duplicate packets and eliminate duplicate copies on the receiving side.

[0010] End to end redundant transmission using dual connectivity may be supported, e.g., as defined in 3GPP TS 23.501 V17.9.0, section 5.33.2.1. The terminals may establish two redundant PDU Sessions and use upper layer protocols to send the same traffic over the two PDU Sessions through both the RAN and the core network (CN). For example, Annex F in 3GPP TS 23.501 V17.9.0 describes the case of multiple UEs per device, each connecting to the 3 GPP network, such that the path over the 3 GPP network is redundant. This is applicable for devices which are equipped with multiple UEs, and where the network supports this deployment.

[0011] In addition, user plane redundancy between UE and UPF may be used, where a single UPF is selected to perform the replication and elimination function. The replication may be realized under the 3 GPP operator’s control between the terminal and the common UPF. A single UE with dual connectivity, or multiple UEs may be used.

[0012] However, PDCP duplication applies redundancy to the air interface only and is not applicable for the rest of the end to end user plane path. N3 / N9 duplication applies redundancy only over the N3 / N9 interface and is not applicable for the rest of the end to end user plane path. The case is the same with transport network-based redundancy on N3 / N9. For dual connectivity based redundancy and for the multiple UE approach, the 3 GPP solution provides a way to establish two PDU Sessions that have different paths. This can be utilized in an end to end redundancy solution as components, but the actual replication and elimination of the packets takes place outside the 3GPP network, defined by other mechanisms such as the Institute of Electrical and Electronics Engineers (IEEE) time-sensitive networking (TSN) frame replication and elimination (FRER) or The Internet Engineering Task Force (IETF) deterministic networking (DetNet) packet replication and elimination (and ordering) function (PREOF). This may be used for redundancy, but in many scenarios, it requires extra effort and cost to deploy such solutions due to the dependency to set up the redundancy by entities that are external to the 3 GPP operator.

[0013] Although a single UPF may selected to perform the replication and elimination function, selecting a single UPF for the PDU Sessions taking part in the redundant handling has drawbacks, and a network operator may want to choose a separate UPF for terminating the redundant paths. Such motivations may be, for example, that only a limited number of UPFs in the network support the termination of redundant paths, and some of the regular UPFs cannot perform such tasks. The UPF which terminates the redundant paths is deployed next to the Application Server (AS) so that the AS provider can avoid deploying redundancy solutions on its own, and instead relies on the 3GPP operator provided function.

[0014] SUMMARY

[0015] Some embodiments advantageously provide methods, systems, and apparatuses for configuration and use of a standalone UPF network node for replication and elimination function. It may be beneficial for a 3GPP operator to be able to start / terminate redundant path within a 5G system (5GS), e.g., so that the operator does not have to rely on an external node or entity for this function. Further, replication and elimination may be realized in a separate node that is co-located with a UPF network node, e.g., by terminating redundant paths at standalone UPF network node.

[0016] According to one aspect, a method in a session management function (SMF) network node configured to communicate with at least one of a first user plane function (UPF) network node, a second UPF network node, and a third UPF network node is described. The first UPF network node is associated with a first packet replication and elimination and ordering function (PREOF). The method includes determining that at least one of a first packet data unit (PDU) session and a second PDU session is associated with a redundant traffic handling of data packets associated with at least one user equipment (UE) based on at least one of a configuration, subscription information, a UE indication, and a request or response from a control entity. The method also includes selecting the first UPF network node to perform the redundant traffic handling of data packets associated with the at least one UE, the first PDU session, and the second PDU session based on the determination. The redundant traffic handling is performed using the first PREOF, a first tunnel associated with the first PDU session, where the first tunnel is at least between the first UPF network node and the second UPF network node, and a second tunnel associated with the second PDU session. The second tunnel is at least between the first UPF network node and the third UPF network node. The method also includes causing the first UPF network node to perform the redundant traffic handling.

[0017] In some embodiments, performing the redundant traffic handling includes performing an action associated with the first PREOF.

[0018] In some other embodiments, the method further includes receiving an indication indicating at least one of whether at least one of the first PDU session and the second PDU session is associated with the redundant traffic handling and whether one UPF network node is needed for the redundant traffic handling.

[0019] In some embodiments, the selection of the first UPF network node is based on at least one of a data network name (DNN) and single network slice selection assistance information (S-NSSAI).

[0020] In some other embodiments, the method further includes establishing the first tunnel at least between the first UPF network node and the second UPF network node and the second tunnel at least between the first UPF network node and the third UPF network node. The second UPF network node is configured as a first PDU session anchor, and the third UPF network node is configured as a second PDU session anchor.

[0021] In some embodiments, the first tunnel and the second tunnel are each a general packet radio services (GPRS) tunnelling protocol (GTP) tunnel.

[0022] In some other embodiments, the method further includes determining a first tunnel endpoint of the first tunnel at the second UPF network node, determining a second tunnel endpoint of the second tunnel at the third UPF network node, establishing a first tunnel forwarding from the second UPF network node to the first UPF network node, and establishing a second tunnel forwarding from the third UPF network node to the first UPF network node.

[0023] In some embodiments, the method further includes updating the first tunnel endpoint and the second tunnel endpoint to establish forwarding from the first UPF network node to the second UPF network node and the third UPF network node, respectively.

[0024] In some other embodiments, the at least one UE is associated with a second PREOF, and the method further includes establishing the first tunnel and the second tunnel between the first PREOF and the second PREOF via the first UPF network node.

[0025] In some embodiments, the selection of the first UPF network node is further based on a query to a database network node.

[0026] In some other embodiments, the method further includes configuring filtering rules for the first UPF network node and the second UPF network node to separate traffic to be tunneled to the first UPF network node.

[0027] In some embodiments, the SMF network node is a first SMF network node configured to manage the first PDU session and the second PDU session, a second SMF network node configured to manage the first PDU session, or a third SMF network node configured to manage the second PDU session.

[0028] In some other embodiments, the method further includes when the SMF network node is configured to manage the first PDU session and the second PDU session, receiving identity information of the second UPF network node and the third UPF network node to identify traffic assigned to the first PDU session and the second PDU session.

[0029] According to another aspect, a session management function (SMF) network node configured to communicate with at least one of a first user plane function (UPF) network node, a second UPF network node, and a third UPF network node is described. The first UPF network node is associated with a first packet replication and elimination and ordering function (PREOF). The SMF network node is configured to determine that at least one of a first packet data unit (PDU) session and a second PDU session is associated with a redundant traffic handling of data packets associated with at least one user equipment (UE) based on at least one of a configuration, subscription information, a UE indication, and a request or response from a control entity. The SMF network node is also configured to select the first UPF network node to perform the redundant traffic handling of data packets associated with the at least one UE, the first PDU session, and the second PDU session based on the determination. The redundant traffic handling being performed using the first PREOF, a first tunnel associated with the first PDU session, where the first tunnel being at least between the first UPF network node and the second UPF network node, and a second tunnel associated with the second PDU session. The second tunnel is at least between the first UPF network node and the third UPF network node. The SMF network node is configured to cause the first UPF network node to perform the redundant traffic handling.

[0030] In some embodiments, performing the redundant traffic handling includes performing an action associated with the first PREOF.

[0031] In some other embodiments, the SMF network node is further configured to receive an indication indicating at least one of whether at least one of the first PDU session and the second PDU session is associated with the redundant traffic handling and whether one UPF network node is needed for the redundant traffic handling.

[0032] In some embodiments, the selection of the first UPF network node is based on at least one of a data network name (DNN) and single network slice selection assistance information (S-NSSAI).

[0033] In some other embodiments, the SMF network node is further configured to establish the first tunnel at least between the first UPF network node and the second UPF network node and the second tunnel at least between the first UPF network node and the third UPF network node. The second UPF network node is configured as a first PDU session anchor, and the third UPF network node is configured as a second PDU session anchor.

[0034] In some embodiments, the first tunnel and the second tunnel are each a general packet radio services (GPRS) tunnelling protocol (GTP) tunnel.

[0035] In some other embodiments, the SMF network node is further configured to determine a first tunnel endpoint of the first tunnel at the second UPF network node, determine a second tunnel endpoint of the second tunnel at the third UPF network node, establish a first tunnel forwarding from the second UPF network node to the first UPF network node, and establish a second tunnel forwarding from the third UPF network node to the first UPF network node.

[0036] In some embodiments, the SMF network node is further configured to update the first tunnel endpoint and the second tunnel endpoint to establish forwarding from the first UPF network node to the second UPF network node and the third UPF network node, respectively. In some other embodiments, the at least one UE is associated with a second PREOF, and the SMF network node is further configured to establish the first tunnel and the second tunnel between the first PREOF and the second PREOF via the first UPF network node.

[0037] In some embodiments, the selection of the first UPF network node is further based on a query to a database network node.

[0038] In some other embodiments, the SMF network node is further configured to configure filtering rules for the first UPF network node and the second UPF network node to separate traffic to be tunneled to the first UPF network node.

[0039] In some embodiments, the SMF network node is a first SMF network node configured to manage the first PDU session and the second PDU session, a second SMF network node configured to manage the first PDU session, or a third SMF network node configured to manage the second PDU session.

[0040] In some other embodiments, the SMF network node is further configured to when the SMF network node is configured to manage the first PDU session and the second PDU session, receive identity information of the second UPF network node and the third UPF network node to identify traffic assigned to the first PDU session and the second PDU session.

[0041] According to one aspect, a method in a first user plane function (UPF) network node configured to communicate with a second UPF network node, a third UPF network node, and at least one user equipment (UE) is described. The first UPF network node is different from at least one of the second UPF network node and the third UPF network node. The first UPF network node is associated with a first packet replication and elimination and ordering function (PREOF). The method includes performing redundant traffic handling of data packets associated with the at least one UE, a first packet data unit (PDU) session, and a second PDU session. The redundant traffic handling being performed using the first PREOF. a first tunnel associated with the first PDU session and a second tunnel associated with the second PDU session. The first tunnel is at least between the first UPF network node and the second UPF network node, and the second tunnel is at least between the first UPF network node and the third UPF network node.

[0042] In some embodiments, performing the redundant traffic handling includes performing an action associated with the first PREOF. In some other embodiments, the first UPF network node is selected by a session management function (SMF) network node to perform the redundant traffic handling based on at least one of a data network name (DNN) and single network slice selection assistance information (S-NSSAI).

[0043] In some embodiments, the second UPF network node is configured as a first PDU session anchor, and the third UPF network node is configured as a second PDU session anchor.

[0044] In some other embodiments, the first tunnel and the second tunnel are each a general packet radio services (GPRS) tunnelling protocol (GTP) tunnel.

[0045] In some embodiments, the first tunnel has a first tunnel endpoint at the second UPF network node, and the second tunnel has a second tunnel endpoint at the third UPF network node. A first tunnel forwarding is established from the second UPF network node to the first UPF network node and a second tunnel forwarding is established from the third UPF network node to the first UPF network node.

[0046] In some other embodiments, the first tunnel endpoint and the second tunnel endpoint are updated to establish forwarding from the first UPF network node to the second UPF network node and the third UPF network node, respectively.

[0047] In some embodiments, the at least one UE is associated with a second PREOF, and the method further includes at least one of transmitting and receiving the data packets via the first tunnel and the second tunnel between the first PREOF and the second PREOF.

[0048] According to another aspect, a first user plane function (UPF) network node configured to communicate with a second UPF network node, a third UPF network node, and at least one user equipment (UE) is described. The first UPF network node is different from at least one of the second UPF network node and the third UPF network node. The first UPF network node is associated with a first packet replication and elimination and ordering function (PREOF). The first UPF network node is configured to perform redundant traffic handling of data packets associated with the at least one UE, a first packet data unit (PDU) session, and a second PDU session. The redundant traffic handling being performed using the first PREOF. a first tunnel associated with the first PDU session and a second tunnel associated with the second PDU session. The first tunnel is at least between the first UPF network node and the second UPF network node, and the second tunnel is at least between the first UPF network node and the third UPF network node. In some embodiments, performing the redundant traffic handling includes performing an action associated with the first PREOF.

[0049] In some other embodiments, the first UPF network node is selected by a session management function (SMF) network node to perform the redundant traffic handling based on at least one of a data network name (DNN) and single network slice selection assistance information (S-NSSAI).

[0050] In some embodiments, the second UPF network node is configured as a first PDU session anchor, and the third UPF network node is configured as a second PDU session anchor.

[0051] In some other embodiments, the first tunnel and the second tunnel are each a general packet radio services (GPRS) tunnelling protocol (GTP) tunnel.

[0052] In some embodiments, the first tunnel has a first tunnel endpoint at the second UPF network node, the second tunnel has a second tunnel endpoint at the third UPF network node, a first tunnel forwarding is established from the second UPF network node to the first UPF network node, and a second tunnel forwarding is established from the third UPF network node to the first UPF network node.

[0053] In some other embodiments, the first tunnel endpoint and the second tunnel endpoint are updated to establish forwarding from the first UPF network node to the second UPF network node and the third UPF network node, respectively.

[0054] In some embodiments, the at least one UE is associated with a second PREOF, and first UPF network node is further configured to at least one of transmit and receive the data packets via the first tunnel and the second tunnel between the first PREOF and the second PREOF.

[0055] BRIEF DESCRIPTION OF THE DRAWINGS

[0056] A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

[0057] FIG. 1 is a schematic diagram of an example network architecture illustrating a communication system according to principles disclosed herein;

[0058] FIG. 2 is a block diagram of a network node in communication with a user equipment over a wireless connection according to some embodiments of the present disclosure; FIG. 3 is a flowchart of an example process in an SMF network node according to some embodiments of the present disclosure;

[0059] FIG. 4 is a flowchart of an example process in a standalone UPF network node according to some embodiments of the present disclosure;

[0060] FIG. 5 shows an example system setup according to some embodiments of the present disclosure;

[0061] FIG. 6 shows an example PREOF functionality realized as a function inside a UPF network node according to some embodiments of the present disclosure;

[0062] FIG. 7 shows another example PREOF realized in a separate network node which may be co-located with a UPF network node according to some embodiments of the present disclosure;

[0063] FIG. 8 shows another example PREOF deployed outside of a 5GS according to some embodiments of the present disclosure;

[0064] FIG. 9 shows another example PREOF deployed co-located with an AS according to some embodiments of the present disclosure;

[0065] FIG. 10 shows example steps of a process for configuring a UPF network node according to some embodiments of the present disclosure;

[0066] FIG. 11 shows other example steps of the process for configuring the UPF network node according to some embodiments of the present disclosure; and

[0067] FIG. 12 shows an example process for selecting and using a UPF network node according to some embodiments of the present disclosure.

[0068] DETAILED DESCRIPTION

[0069] Before describing in detail exemplary embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to configuration and use of a standalone UPF network node for replication and elimination function. Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0070] As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and / or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0071] In embodiments described herein, the joining term, “in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate, and modifications and variations are possible of achieving the electrical and data communication.

[0072] In some embodiments described herein, the term “coupled,” “connected,” and the like, may be used herein to indicate a connection, although not necessarily directly, and may include wired and / or wireless connections.

[0073] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and / or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0074] The term “network node” used herein can be any kind of network node comprised in a radio network which may further comprise any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multi- standard radio (MSR) radio node such as MSR BS, multi-cell / multicast coordination entity (MCE), relay node, donor node controlling relay, radio access point (AP), transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH), a core network node (e.g., mobile management entity (MME), selforganizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc. The network node may also comprise test equipment. In some embodiments, the network node may comprise and / or configured to perform functions associated with a UPF, RAN node, an application management function (AMF), an SMF, etc. In some other embodiments, a network node that comprises and / or is configured to perform functions associated with a UPF, RAN node, an application management function (AMF), and an SMF may be referred to as a UPF network node, a RAN network node, an AMF network node, an SMF network node, respectively. Other network nodes may be referred to by the term network node preceded by the function for which the network node is configured or entity that the network node comprises. The term “radio node” used herein may be used to also denote a user equipment (UE) such as a wireless device (WD) or a radio network node.

[0075] In some embodiments, the non-limiting terms wireless device (WD) or a user equipment (UE) are used interchangeably. The UE herein can be any type of wireless device capable of communicating with a network node or another UE over radio signals, such as a wireless device (WD). The UE may also be a radio communication device, target device, device to device (D2D) UE, machine type UE or UE capable of machine to machine communication (M2M), low-cost and / or low-complexity UE, a sensor equipped with UE, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (loT) device, or a Narrowband loT (NB-IOT) device etc.

[0076] Also, in some embodiments the generic term “radio network node” is used. It can be any kind of a radio network node which may comprise any of base station, radio base station, base transceiver station, base station controller, network controller, RNC, evolved Node B (eNB), Node B, gNB, Multi-cell / multicast Coordination Entity (MCE), relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH).

[0077] Note that although terminology from one particular wireless system, such as, for example, 3GPP LTE and / or New Radio (NR), may be used in this disclosure, this should not be seen as limiting the scope of the disclosure to only the aforementioned system. Other wireless systems, including without limitation Wide Band Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM), may also benefit from exploiting the ideas covered within this disclosure.

[0078] Note further, that functions described herein as being performed by a user equipment or a network node may be distributed over a plurality of user equipments and / or network nodes. In other words, it is contemplated that the functions of the network node and user equipment described herein are not limited to performance by a single physical device and, in fact, can be distributed among several physical devices.

[0079] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0080] Referring to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in FIG. 1 a schematic diagram of a communication system 10, according to an embodiment, such as a 3GPP-type cellular network that may support standards such as LTE and / or NR (5G), which comprises an access network 12, such as a radio access network, and a core network 14. The access network 12 comprises a plurality of network nodes 16a, 16b, 16c (referred to collectively as network nodes 16), such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (referred to collectively as coverage areas 18). Core network node may include one or more network nodes 16 such as network node 16d. Each network node 16a, 16b, 16c is connectable to the core network 14 (and / or any of the network nodes 16 in the core network 14 such as network node 16) over a wired or wireless connection 20. A first user equipment (UE) 22a located in coverage area 18a is configured to wirelessly connect to, or be paged by, the corresponding network node 16a. A second UE 22b in coverage area 18b is wirelessly connectable to the corresponding network node 16b. While a plurality of UEs 22a, 22b (collectively referred to as user equipment 22) are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding network node 16. Note that although only two UEs 22 and three network nodes 16 are shown for convenience, the communication system may include many more UEs 22 and network nodes 16.

[0081] Also, it is contemplated that a UE 22 can be in simultaneous communication and / or configured to separately communicate with more than one network node 16 and more than one type of network node 16. For example, a UE 22 can have dual connectivity with a network node 16 that supports LTE and the same or a different network node 16 that supports NR. As an example, UE 22 can be in communication with an eNB for LTE / E-UTRAN and a gNB for NR / NG-RAN.

[0082] A network node 16 is configured to include a node management unit 24 which is configured to perform any step and / or task and / or process and / or method and / or feature described in the present disclosure, e.g., network node functions. A UE 22 is configured to include a UE management unit 26 which is configured to perform any step and / or task and / or process and / or method and / or feature described in the present disclosure, e.g., UE functions.

[0083] Example implementations, in accordance with an embodiment, of the UE 22 and network node 16 discussed in the preceding paragraphs will now be described with reference to FIG. 2.

[0084] The communication system 10 includes a network node 16 provided in a communication system 10 which includes hardware 28 enabling it to communicate with the UE 22. The hardware 28 may include a radio interface 30 for setting up and maintaining at least a wireless connection 32 with a UE 22 located in a coverage area 18 served by the network node 16. The radio interface 30 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and / or one or more RF transceivers. The radio interface 30 includes an array of antennas 34 to radiate and receive signal(s) carrying electromagnetic waves.

[0085] In the embodiment shown, the hardware 28 of the network node 16 further includes processing circuitry 36. The processing circuitry 36 may include a processor 38 and a memory 40. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 36 may comprise integrated circuitry for processing and / or control, e.g., one or more processors and / or processor cores and / or FPGAs (Field Programmable Gate Array) and / or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 38 may be configured to access (e.g., write to and / or read from) the memory 40, which may comprise any kind of volatile and / or nonvolatile memory, e.g., cache and / or buffer memory and / or RAM (Random Access Memory) and / or ROM (Read- Only Memory) and / or optical memory and / or EPROM (Erasable Programmable Read- Only Memory).

[0086] Thus, the network node 16 further has software 42 stored internally in, for example, memory 40, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the network node 16 via an external connection. The software 42 may be executable by the processing circuitry 36. The processing circuitry 36 may be configured to control any of the methods and / or processes described herein and / or to cause such methods, and / or processes to be performed, e.g., by network node 16. Processor 38 corresponds to one or more processors 38 for performing network node 16 functions described herein. The memory 40 is configured to store data, programmatic software code and / or other information described herein. In some embodiments, the software 42 may include instructions that, when executed by the processor 38 and / or processing circuitry 36, causes the processor 38 and / or processing circuitry 36 to perform the processes described herein with respect to network node 16. For example, processing circuitry 36 of the network node 16 may include a node management unit 24 which is configured to perform any step and / or task and / or process and / or method and / or feature described in the present disclosure, e.g., network node functions.

[0087] The communication system 10 further includes the UE 22 already referred to. The UE 22 may have hardware 44 that may include a radio interface 46 configured to set up and maintain a wireless connection 32 with a network node 16 serving a coverage area 18 in which the UE 22 is currently located. The radio interface 46 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and / or one or more RF transceivers. The radio interface 46 includes an array of antennas 48 to radiate and receive signal(s) carrying electromagnetic waves.

[0088] The hardware 44 of the UE 22 further includes processing circuitry 50. The processing circuitry 50 may include a processor 52 and memory 54. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 50 may comprise integrated circuitry for processing and / or control, e.g., one or more processors and / or processor cores and / or FPGAs (Field Programmable Gate Array) and / or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 52 may be configured to access (e.g., write to and / or read from) memory 54, which may comprise any kind of volatile and / or nonvolatile memory, e.g., cache and / or buffer memory and / or RAM (Random Access Memory) and / or ROM (Read-Only Memory) and / or optical memory and / or EPROM (Erasable Programmable Read-Only Memory).

[0089] Thus, the UE 22 may further comprise software 56, which is stored in, for example, memory 54 at the UE 22, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the UE 22. The software 56 may be executable by the processing circuitry 50. The software 56 may include a client application 58. The client application 58 may be operable to provide a service to a human or non-human user via the UE 22.

[0090] The processing circuitry 50 may be configured to control any of the methods and / or processes described herein and / or to cause such methods, and / or processes to be performed, e.g., by UE 22. The processor 52 corresponds to one or more processors 52 for performing UE 22 functions described herein. The UE 22 includes memory 54 that is configured to store data, programmatic software code and / or other information described herein. In some embodiments, the software 56 and / or the client application 58 may include instructions that, when executed by the processor 52 and / or processing circuitry 50, causes the processor 52 and / or processing circuitry 50 to perform the processes described herein with respect to UE 22. For example, the processing circuitry 50 of the user equipment 22 may include a UE management unit 26 which is configured to perform any step and / or task and / or process and / or method and / or feature described in the present disclosure, e.g., UE functions.

[0091] In some embodiments, the inner workings of the network node 16 and UE 22 may be as shown in FIG. 2 and independently, the surrounding network topology may be that of FIG. 1.

[0092] The wireless connection 32 between the UE 22 and the network node 16 is in accordance with the teachings of the embodiments described throughout this disclosure. More precisely, the teachings of some of these embodiments may improve the data rate, latency, and / or power consumption and thereby provide benefits such as reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime, etc. In some embodiments, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. Although FIGS. 1 and 2 show various “units” such as node management unit 24 and UE management unit 26 as being within a respective processor, it is contemplated that these units may be implemented such that a portion of the unit is stored in a corresponding memory within the processing circuitry. In other words, the units may be implemented in hardware or in a combination of hardware and software within the processing circuitry.

[0093] FIG. 3 is a flowchart of an example process in an SMF network node 16. One or more blocks described herein may be performed by one or more elements of network node 16 such as by one or more of processing circuitry 36 (including the node management unit 24), processor 38, and / or radio interface 30. SMF network node 16 such as via processing circuitry 36 and / or processor 38 and / or radio interface 30 is configured to determine (Block S 100) that at least one of a first packet data unit (PDU) session and a second PDU session is associated with a redundant traffic handling of data packets associated with at least one user equipment (UE) 22 based on at least one of a configuration, subscription information, a UE indication, and a request or response from a control entity. SMF network node 16 is also configured to select (Block S 102) the first UPF network node 16a to perform the redundant traffic handling of data packets associated with the at least one UE 22, the first PDU session, and the second PDU session based on the determination. The redundant traffic handling is performed using the first PREOF 102a, a first tunnel 102a, 104a associated with the first PDU session and a second tunnel 102b, 104b associated with the second PDU session. The first tunnel 102a, 104a is at least between the first UPF network node 16a and the second UPF network node 16b. The second tunnel 102b, 104b is at least between the first UPF network node 16a and the third UPF network node 16c. SMF network node 16 is also configured to cause (Block S 104) the first UPF network node 16a to perform the redundant traffic handling (e.g., via a configuration, indication, signaling, etc.).

[0094] In some embodiments, performing the redundant traffic handling includes performing an action associated with the first PREOF 102a.

[0095] In some other embodiments, the method further includes receiving an indication indicating at least one of whether at least one of the first PDU session and the second PDU session is associated with the redundant traffic handling and whether one UPF network node 16 is needed for the redundant traffic handling. In some embodiments, the selection of the first UPF network node 16a is based on at least one of a data network name (DNN) and single network slice selection assistance information (S-NSSAI).

[0096] In some other embodiments, the method further includes establishing the first tunnel 102a, 104a at least between the first UPF network node 16a and the second UPF network node 16b and the second tunnel 102b, 104b at least between the first UPF network node 16a and the third UPF network node 16c. The second UPF network node 16b is configured as a first PDU session anchor, and the third UPF network node 16c is configured as a second PDU session anchor.

[0097] In some embodiments, the first tunnel 102a, 104a and the second tunnel 102b, 104b are each a general packet radio services (GPRS) tunnelling protocol (GTP) tunnel.

[0098] In some other embodiments, the method further includes determining a first tunnel endpoint of the first tunnel 102a, 104a at the second UPF network node 16b, determining a second tunnel endpoint of the second tunnel 102a, 104a at the third UPF network node 16c, establishing a first tunnel forwarding from the second UPF network node 16b to the first UPF network node 16a, and establishing a second tunnel forwarding from the third UPF network node 16c to the first UPF network node 16a.

[0099] In some embodiments, the method further includes updating the first tunnel endpoint and the second tunnel endpoint to establish forwarding from the first UPF network node 16a to the second UPF network node 16b and the third UPF network node 16c, respectively.

[0100] In some other embodiments, the at least one UE 22 is associated with a second PREOF 102b, and the method further includes establishing the first tunnel 102a and the second tunnel 102b between the first PREOF 102a and the second PREOF 102b via the first UPF network node 16a.

[0101] In some embodiments, the selection of the first UPF network node 16a is further based on a query to a database network node 16j.

[0102] In some other embodiments, the method further includes configuring filtering rules for the first UPF network node 16a and the second UPF network node 16b to separate traffic to be tunneled to the first UPF network node 16a.

[0103] In some embodiments, the SMF network node 16 is a first SMF network node 16d configured to manage the first PDU session and the second PDU session (e.g., as SMF0), a second SMF network node 16e configured to manage the first PDU session, or a third SMF network node 16f configured to manage the second PDU session. In some other embodiments, the method further includes when the SMF network node 16 is configured to manage the first PDU session and the second PDU session, receiving identity information of the second UPF network node 16b and the third UPF network node to identify traffic assigned to the first PDU session and the second PDU session.

[0104] FIG. 4 is a flowchart of an example process in a UPF network node 16 (e.g., UPF network node 16a). One or more blocks described herein may be performed by one or more elements of network node 16 such as by one or more of processing circuitry 36 (including the node management unit 24), processor 38, and / or radio interface 30. UPF network node 16 such as via processing circuitry 36 and / or processor 38 and / or radio interface 30 is configured to perform (Block S 106) redundant traffic handling of data packets associated with the at least one UE 22, a first packet data unit (PDU) session, and a second PDU session. The redundant traffic handling is performed using the first PREOF 102a, a first tunnel 102a, 104a associated with the first PDU session, where the first tunnel 102a, 104a is at least between the first UPF network node 16a and the second UPF network node 16b, and a second tunnel 102b, 104b associated with the second PDU session. The second tunnel 102b, 104b is at least between the first UPF network node 16a and the third UPF network node 16c.

[0105] In some embodiments, performing the redundant traffic handling includes performing an action associated with the first PREOF 102a.

[0106] In some other embodiments, the first UPF network node 16a is selected by a session management function (SMF) network node 16 to perform the redundant traffic handling based on at least one of a data network name (DNN) and single network slice selection assistance information (S-NSSAI).

[0107] In some embodiments, the second UPF network node 16b is configured as a first PDU session anchor, and the third UPF network node 16c is configured as a second PDU session anchor.

[0108] In some other embodiments, the first tunnel 102a, 104a and the second tunnel are each a general packet radio services (GPRS) tunnelling protocol (GTP) tunnel.

[0109] In some embodiments, the first tunnel 102a, 104a has a first tunnel endpoint at the second UPF network node 16b, and the second tunnel 102b, 104b has a second tunnel endpoint at the third UPF network node 16c. A first tunnel forwarding is established from the second UPF network node 16b to the first UPF network node 16a and a second tunnel forwarding is established from the third UPF network node 16c to the first UPF network node 16a.

[0110] In some other embodiments, the first tunnel endpoint and the second tunnel endpoint are updated to establish forwarding from the first UPF network node 16a to the second UPF network node 16b and the third UPF network node 16c, respectively.

[0111] In some embodiments, the at least one UE 22 is associated with a second PREOF 102b, and the method further includes at least one of transmitting and receiving the data packets via the first tunnel 102a and the second tunnel 102b between the first PREOF 102a and the second PREOF 102b.

[0112] Having described the general process flow of arrangements of the disclosure and having provided examples of hardware and software arrangements for implementing the processes and functions of the disclosure, the sections below provide details and examples of arrangements for configuration and use of a standalone UPF network node 16 for replication and elimination function. In some embodiments, the term UPFx is used and may refer to one or more UPF network nodes 16 (such as UPF1, UPF2, etc.).

[0113] In some embodiments, the user plane (or data packets associated with the user plane) passes through a first UPF network node 16, e.g., UPF0, that is different from at least one of two other UPF network nodes 16, i.e., a second UPF network node 16 and a third UPF network node 16 (e.g., UPF1 and UPF2, respectively), corresponding to two PDU Sessions that take part in the redundant user plane handling. GTP tunneling is used between the first UPF network node 16 and the second and third UPF network nodes 16 (where at least one of second and third UPF network nodes 16 is separate from the first UPF network node 16). The function for packet replication and elimination of the redundant traffic is located at or near the first UPF network node 16. The tunneling to and from the first UPF network node 16 is established by an SMF function, i.e., an SMF network node 16.

[0114] In some embodiments, a single UE 22 (e.g., as part of a device) is described as being associated with multiple PDU sessions. However, the embodiments are not limited as such and multiple UEs 22 devices (as part of a device or more) may be supported, e.g., where each UE 22 is associated with one or more PDU Sessions.

[0115] An example system setup is shown in FIG. 5. System 10 includes a first UPF network node 16a (UPF0), a second UPF network node 16b (UPF1), a third UPF network node 16c (UPF2), a first SMF network node 16d (SMF0) (which may be optional), a second SFM network node 16e (SMF1), a third SMF network node 16f (SMF2), an AMF network node 16g (AMF), a first RAN network node 16h (RANI), a second RAN network node 16i (RAN2), a UE 22 (or more UEs), PREOF 100a, and PREOF 100b.

[0116] Signaling (e.g., such as data packets associated with PDU sessions) may be transmitted between the UE 22 (and / or PREOF 100b) and the first UPF network node 16a (and / or PREOF 100a) via tunnel 102a and tunnel 102b, where the signaling may be associated with redundant traffic handling. Signaling transmitted via tunnel 102a may be redundant with respect to signaling that is transmitted via tunnel 102b. Tunnels 102a, 102b may be referred to as paths. Further, signaling transmitted using tunnel 102a may be processed by the first RAN network node 16h and second UPF network node 16b. Similarly, signaling transmitted using tunnel 102b may be processed by the second RAN network node 16i and third UPF network node 16c.

[0117] Further, tunnel 104a may be established between the first UPF network node 16a and second UPF network node 16b. Similarly, tunnel 104b may be established between the first UPF network node 16a and third UPF network node 16c. In some embodiments, tunnel 104a is comprised in or associated with tunnel 102a, and tunnel 104b is comprised in or associated with tunnel 102b. Although not all connections are shown for ease of understanding, any component of system 10 shown in FIG. 5 may communicate with any other component of the system 10.

[0118] PREOFs 100a, 100b may be configured to perform packet replication and elimination (and ordering) functions and may be comprised in a network node 16. In some embodiments, PREOFs 100a, 100b are located at or near the first UPF network node 16a and at or near the UE 22 on the terminal side, respectively. The first and second SMF network nodes 16e, 16f may be configured to establish two PDU Sessions which are responsible for establishing tunnels 104a, 104b (GTP tunnels), respectively.

[0119] There may be different usage scenarios depending on the deployment, whether PREOF 100a at the network and PREOF 100b at the terminal side are managed by the network operator in the 5G domain or are outside of the 5G domain. In some embodiments, the first UPF network node 16a may be co-located with a PREOF 100a that is managed by the network operator. In some other embodiments, first UPF network node 16a is co-located with a PREOF 100a at the same location where PREOF functionality is managed by an external operator or service provider. FIG. 6 shows an example PREOF functionality realized as a function inside a first UPF network node 16a. In this case, the role of UPF of the first UPF network node 16a is to terminate the tunnels to and from second UPF network node 16b and third UPF network node 16c and realize the PREOF 100a functionality as a node internal function. In this case, the first UPF network node 16a and the PREOF function within first UPF network node 16a is part of subsystem 110 (e.g., 5GS).

[0120] In some embodiments, the PREOF functionality is realized in a separate network node 16 which may be co-located with the first UPF network node 16a as shown in FIG. 7. In this case, the role of the first UPF network node 16a is to terminate the tunnels towards the second UPF network node 16b and the third UPF network node 16c, and to relay the traffic to and from PREOF 100a, but the actual PREOF functionality is realized separately, e.g., in a standalone network node 16. In this example, the PREOF functionality is part of the operator network.

[0121] In some embodiments, the PREOF 100a is deployed outside of the subsystem 110 (e.g., 5GS), as shown in FIG. 8. For example, the PREOF 100a may be owned by an external provider. The operator may help the deployment with the use of the first UPF network node 16a that manages the tunneling, but the PREOF functionality is kept outside of 5GS.

[0122] In some other embodiment, the PREOF 100a is also co-located with the application (i.e., as AS 106) as shown in FIG. 9. The operator may provide redundancy as a service, and as a way to address redundancy, the operator deploys the first UPF network node 16a close (co-located) with the application function (AF) site, and also deploy PREOF functionality (either in a separate node or within the first UPF network node 16a). In this way, the operator can take the burden of setting up redundancy so that the application does not have to.

[0123] Although embodiments are described with respect to the first UPF network node 16a, similar functions may be performed by the UE 22 or any other component on the UE 22 side.

[0124] In some embodiments, for a PDU session that takes part in redundant handling of traffic, an additional UPF function (i.e., the first UPF network node 16a) is inserted into the user place path above the current PSA. The packet replication and elimination are performed at or near the first UPF network node 16a. GTP tunneling is used to tunnel traffic between the second and third UPF network nodes 16b, 16c acting as the current PSA and the first UPF network node 16a. The embodiments of the present disclosure are beneficial at least because:

[0125] • Packet replication and elimination in the 5GS is supported even if only a limited number of UPFs support the PREOF functionality.

[0126] • It becomes possible to deploy a UPF which terminates the redundant paths next to AS 106 so that the AS provider can avoid deploying redundancy solutions on its own, and instead rely on the 3 GPP operator provided function.

[0127] • In deployments where a separate node implements the PREOF functionality, it becomes possible to co-locate the PREOF with a UPF network node, so the use of the PREOF implemented in a separate node is enabled.

[0128] • Only PREOF traffic may be served at the first UPF network node 16a without an additional PDU session.

[0129] • Dynamic serving of TSN / DetNet traffic may be provided.

[0130] Some embodiments provide setting up the additional UPF node (i.e., the first UPF network node 16a) during PDU Session Establishment. The solution involves the establishment of multiple PDU Sessions from the same end device (i.e., UE 22), so that the selected second UPF network node 16b and third UPF network node 16c for the PDU Sessions are different.

[0131] During the PDU Session establishment, the an SMF network node 16 (e.g., the first, second, or third SMF network node) determines that the PDU Session takes part in redundant handling, and that the first UPF network node 16a (a separate UPFO) is to be selected to perform PREOF functions. This determination may be based on SMF configuration, or subscription information, or terminal (UE) indication, or based on a request / response from a control entity (e.g., central control entity or network node 16). The control entity may include a time sensitive communication and time synchronization function (TSCTSF) or a services digital network (SDN) controller or any other network node or component of system 10. With each of these methods, there may be a separate indication whether the PDU Session takes part in redundant handling, and whether a separate UPFO (i.e., the first UPF network node 16a) is needed for PREOF handling. There may be other scenarios where redundant handling does not require a separate UPF for PREOF function, relying on PREOF functions outside of the 3GPP system. In some embodiments, the SMF network nodes 16 may be different for the two (or more) PDU Sessions taking part in the redundant handling. Nevertheless, they may make the same determination using the same or similar configuration regarding the need for a separate UPF entity.

[0132] In some embodiments, once the SMF network node 16 (e.g., the first, second, or third SMF network node 16d, 16e, 16f) has made the determination that an additional UPF (i.e., the first UPF network node 16a) is needed, the SMF network node 16 (e.g., the first, second, or third SMF network node) selects the first UPF network node 16a. It is ensured that the same first UPF network node 16a is selected for all the redundant PDU Sessions. The selection of the first UPF network node 16a may be based on data network name (DNN), single network slice selection assistance information (S- NSSAI), and any other criteria that can be used for UPF selection (e.g., 3GPP TS 23.501 V17.9.0, section 6.3.3). Additionally, the first UPF network node 16a is selected in such a way that the first UPF network node 16a is capable of performing the PREOF functionality or be co-located with a node that can perform PREOF functionality.

[0133] In some other embodiments, the SMF network node 16 (e.g., the first, second, or third SMF network node 16d, 16e, 16f) establishes the GTP tunneling between the the second UPF network node 16b and / or the third UPF netowrk node 16c acting as the PSA (i.e., UPF1 or UPF2) and the first UPF network node 16a (UPFO). For this, the SMF network node 16 establishes a session at the first UPF network node 16a (may be considered as a special type of N4 session), determines the GTP tunnel endpoint. Further, the SMF network node 16 establishes the GTP tunnel endpoint at the the second UPF network node 16b and / or the third UPF netowrk node 16c and sets up GTP forwarding from the second UPF network node 16b and / or the third UPF netowrk node 16c to the first UPF network node 16a. In addition, the SMF network node 16 updates the GTP endpoint to establish the GTP forwarding from the first UPF network node 16a to the second UPF network node 16b and / or the third UPF netowrk node 16c.

[0134] To prepare for the use of PREOF functionality, a tunnelling may be set up and used between the PREOF functions, e.g., as described e.g., in draft-ietf-detnet-mpls- over-ip-preof-07 (DetNet PREOF via MPLS over UDP / IP) where user datagram protocol (UDP) tunneling is used between the PREOF entities. In some embodiments, “Tunnel termination in 5GS” may refer to a way to establish tunnels to / from 5GS entities. The PREOF functionality may be configured using a controller, such as a DetNet controller (e.g., comprised in a network node 16). The controller may become aware of the PREOF functionality based on topology and capability reporting. As part of the PREOF configuration, it is also configured which traffic the redundancy applies to. The PREOF functionality uses the corresponding filters so that it is applied only for the flows that require redundancy.

[0135] FIGS. 10 and 11 show steps of an example process for configuring a UPF. Additional steps may be merged in as steps within the PDU Session Establishment procedure. UE 22 may include more than one UE and may be referred to as a terminal. On FIG. 10, at step S200, a PDU session is established. At step S202, SMF network node 16e determines the need for redundant handling and a UPF (such as the first UPF network node 16a). At step S204, the SMF network node 16e selects the first UPF network node 16a (UPFO). The SMF (e.g., an SMF network node 16) may establish the GTP tunneling between the UPFx acting as the PSA (i.e., network node 16b (UPF1) or network node 16c (UPF2)) and the network node 16a (UPFO). For this, the SMF establishes a session at network node 16a (UPFO) (may be considered as a special type of N4 session), determines the GTP tunnel endpoint; then the SMF establishes the GTP tunnel endpoint at the UPFx (i.e., network node 16b (UPF1) or network node 16c (UPF2)) and sets up GTP forwarding from the UPFx (i.e., network node 16b (UPF1) or network node 16c (UPF2)) to network node 16a (UPFO) using the following steps. At step S206a, a GTP endpoint is set up, and a response is provided by the first UPF network node 16a, at step S206b. The response may include a successful / failure indication for establishing the tunnel and / or information related to the tunnel endpoints as established at the UPF. At step S208a, a GTP endpoint is set up, and a response is provided by the second UPF network node 16b, at step S208b. The response may include a successful / failure indication for establishing the tunnel and / or information related to the tunnel endpoints as established at the UPF. At step S210a, the GTP tunnel is updated and a response provided, at step S210b. The response may include a successful / failure indication for establishing the tunnel and / or information related to the tunnel endpoints as established at the UPF. On FIG. 11, at step S212, a PDU session is established. At step S214, SMF network node 16f determines the need for redundant handling and a UPF (such as the first UPF network node 16a). At step S216, the first UPF network node 16a is selected. At step S218a, a GTP endpoint is set up, and a response is provided by the first UPF network node 16a, at step S218b. The response may include a successful / failure indication for establishing the tunnel and / or information related to the tunnel endpoints as established at the UPF. At step S220a, a GTP endpoint is set up between network node 16a (UPFO) and network node 16b and / or network node 16c (i.e., UPFx (UPF1 or UPF2)), and a response is provided, e.g., by the third UPF network node 16c, at step S220b. At step S222a, the SMF (e.g., network node 16f (SMF2)) updates the GTP endpoint to establish the GTP forwarding from network node 16a (UPFO) to the network node 16b and / or network node 16c (i.e., UPFx (UPF1 or UPF2)), the GTP tunnel is updated, and a response provided, at step S222b. To prepare for the use of PREOF functionality, a tunnelling may be set up and used between the PREOF functions, as described e.g., in draft-ietf-detnet-mpls-over-ip- preof-07 (DetNet PREOF via MPLS over UDP / IP) where UDP tunneling is used between the PREOF entities (i.e., PREOFs 100a, 100b. At step S224, PREOF tunneling and PREOF function is configured (e.g., as described above).

[0136] Selecting the same UPF network node (UPFO)

[0137] The SMF network nodes 16 used for the two (or more) PDU Sessions taking part in the redundant handling may be different. However, the same UPF network node 16 is selected for both PDU Sessions.

[0138] In some embodiments, the selected UPF network node 16 (UPFO) or information associated with the selected UPF network node 16 is stored at a central server or network node 16 (such as the TSCTSF, the UDM, or an SDN controller), using a terminal identity as the key. (The DNN, and the S-NSSAI may also be added to the key to support configurations with multiple logical networks.) The terminal identity may be a UE identity (such as the subscriber permanent identifier (SUPI)) in case the two PDU Sessions are established from the same UE 22. Alternatively, the terminal identity may be a device name, or device address or other device identity in cases where the two PDU Sessions from the same device are established using different UEs 22. In other embodiments, where the two PDU Sessions are started from different UEs 22, a correlation identifier (ID) may be configured for the PDU Sessions that acts as the key.

[0139] When the second SMF network node 16e selects the first UPF network node 16a, it first checks whether there is already a selected first UPF network node 16a (UPFO) with the key. As there is none, the second SMF network node 16e selects the first UPF network node 16a (UPFO) and stores its identity in the database. The third SMF network node 16f (which may be identical with the second) determines that the first UPF network node 16a (UPFO) is already selected with the given key, so no new first UPF network node 16a (UPFO) selection needs to be performed. In case multiple PDU Sessions are used, the same can be applied for additional PDU Sessions. FIG. 12 shows an example process for selecting and using a first UPF network node 16a (UPFO). The DB network node 16j indicates the database that stores the selected UPFO addresses based on the terminal identity (possibly with DNN, S-NSSAI) as the key; the database may be e.g., in the TSCTSF. At step S300, the second SMF network node 16e (SMF1) performs a query related to the first UPF network node 16a (UPFO), e.g., using a UPFO address. At step S302, a response indicating that such address is not found in the database is transmitted. At step S304, the second SMF network node 16e (SMF1) selects the first UPF network node 16a (UPFO), and at step S306, the identity of the selected first UPF network node 16a (UPFO) is stored. A response, confirming that the identity is stored, is transmitted at step S3O8. At step S310, the same first UPF network node 16a (UPFO) is used. At step S312, the third SMF network node 16f (SMF2) transmits a query similar to the query of step S300. At step S314, the address of the first UPF network node 16a (UPFO) is provided. At step S310, the third SMF network node 16f (SMF2) uses the first UPF network node 16a (UPFO).

[0140] In some embodiments when the SMF network node 16 is the same for all the PDU Sessions with redundant traffic handling, the SMF network node 16 may act as the database, and make sure on its own that the same first UPF network node 16a (UPFO) is selected. The same SMF network node 16 can be ensured, e.g., by SMF selection based on the DNN, S-NSSAI.

[0141] In some embodiments, a first UPF network node 16a (UPFO) may be preassigned in a database for all UEs 22, and PDU Sessions for which redundant handling may be possible. Such pre-assigned first UPF network node 16a (UPFO) is possible in the subscription records, and then the SMF network node 16 can select the first UPF network node 16a (UPFO) based on the pre-assigned value in the subscription.

[0142] In some other embodiments, the same first UPF network node 16a (UPFO) is used for all PDU Sessions taking part in redundancy, where all the individual SMF network nodes 16 are configured in such a way that they all select the same first UPF network node 16a (UPFO) without using a central database. For example, the first UPF network node 16a (UPFO) may be selected based on the DNN, S-NSSAI, so that in a given network, a single first UPF network node 16a (UPFO) is used, making sure it is always the same. The key identifying the terminal may be hashed to select the first UPF network node 16a (UPFO) out of the range of possible nodes. Therefore, with the same key for the terminal, all PDU Sessions would get the same first UPF network node 16a (UPFO) assigned.

[0143] Breaking out non-redundant traffic

[0144] The second UPF network node 16b (UPF1) and third UPF network node 16c (UPF2) may use the tunneling towards the first UPF network node 16a (UPFO) for traffic that is subject to redundant handling. In some embodiments, for other traffic, there is no need to use tunneling towards the first UPF network node 16a (UPFO). Other traffic can be broken out locally at the second UPF network node 16b (UPF1) and third UPF network node 16c (UPF2). There may be other reasons to break out traffic at the second UPF network node 16b (UPF1) and third UPF network node 16c (UPF2), e.g., elimination is carried out outside of 5GS.

[0145] The second SMF network node 16e (SMF1) and third SMF network node 16f (SMF2) may configure filtering rules into the second UPF network node 16b (UPF1) and third UPF network node 16c (UPF2) to separate which traffic needs to be tunneled to the first UPF network node 16a (UPFO). As an example, in case UDP tunneling is used for the traffic that is subject to redundant handling, it is possible to filter on the UDP tunnel headers (i.e., with a destination IP address that belongs to the first UPF network node 16a (UPFO)) and forward such traffic to the first UPF network node 16a (UPFO). Other types of tunneling or filtering information may also be possible.

[0146] In some embodiments, an operator may also decide to tunnel all traffic via the first UPF network node 16a (UPFO). In that case, there is no need for special filtering rules at the second UPF network node 16b (UPF1) and third UPF network node 16c (UPF2), and also there is no need to separately show second UPF network node 16b (UPF1) and third UPF network node 16c (UPF2) as routers towards the external controller.

[0147] Using a first SMF network node (SMFO) for a first UPF network node (UPFO)

[0148] In some embodiments, a special SMF, denoted here as the first SMF network node 16d (SMFO), as shown in FIG. 5, may be used to manage the tunneling between the first UPF network node 16a (UPFO) and the individual second and third UPF network nodes (UPF1, UPF2). The second SMF network node 16e (SMF1) and third SMF network node 16f (SMF2) are used for the individual PDU Sessions, and the first SMF network node 16d (SMFO) is used for setting up the tunneling between the first UPF network node 16a (UPFO) and the second UPF network node 16b (UPF1) and / or the third UPF network node 16c (UPF2). During the PDU Session establishment, the second SMF network node 16e (SMF1) and third SMF network node 16f (SMF2) determine that the PDU Session takes part in redundant traffic handling, and a separate the first UPF network node 16a (UPFO) is to be established. When this determination is made, the first SMF network node 16d (SMFO) is selected so that there is a single first SMF network node 16d (SMFO) for both PDU Sessions. This can be guaranteed in a similar way as the single first UPF network node 16a (UPFO): either use a single first SMF network node 16d (SMFO) in the given network instance (identified by DNN, S-NSSAI), or a hash of the terminal identifier to select one first SMF network node 16d (SMFO) out of a range of possibilities. Alternatively, the identity of the selected first SMF network node 16d (SMFO) may be stored which may be used for the second PDU Session once first SMF network node 16d (SMFO) is already selected.

[0149] When first SMF network node 16d (SMFO) is selected, the second SMF network node 16e (SMF1) or third SMF network node 16f (SMF2) contacts the first SMF network node 16d (SMFO) and also provides the identity of the selected second UPF network node 16b (UPF1) and / or third UPF network node 16c (UPF2), and also the information needed to identify the traffic such as the internet protocol (IP) address assigned to the PDU Sessions. Then, the first SMF network node 16d (SMFO) selects the first UPF network node 16a (UPFO), this could be performed as described earlier, or it may also be possible that based on the identity of the first SMF network node 16d (SMFO), the first UPF network node 16a (UPFO) could be uniquely selected. Then, if needed, the first SMF network node 16d (SMFO) sets up the tunneling between the second UPF network node 16b (UPF1) and / or the third UPF network node 16c (UPF2) and the first UPF network node 16a (UPFO).

[0150] The use of a separate the first SMF network node 16d (SMFO) entity may in some cases be beneficial, as a separate the first SMF network node 16d (SMFO) is responsible for managing the tunneling that is on a group level, i.e., can be used for multiple UEs 22, while the individual SMF network nodes 16 are responsible for the individual PDU Sessions.

[0151] Note that in this case, it may be possible to set up only a single GTP tunnel between the individual UPF network nodes 16 that is used for multiple PDU Sessions. For example, between the first UPF network node 16a (UPFO) and the second UPF network node 16b (UPF1), there may be only a single PDU Session that may be used for many UEs 22, and similarly between the first UPF network node 16a (UPFO) and the third UPF network node 16c (UPF2), a single tunnel may be shared by many UEs 22. This can help to reduce the number of tunnels. Each time a new UE 22 is added, it may be sufficient to update the filtering rules and just map the traffic of the new UE 22 to the tunnel, but there is no need to add new tulles as such.

[0152] Topology information from the first UPF network node 16a (UPFO)

[0153] In the network topology that is exposed from the 5GS system, the use of the first UPF network node 16a (UPFO) may be regarded as a separate node. This is not necessarily a requirement in all cases. In some embodimetns, where DetNet or TSN integration of the 5GS system is used, the first UPF network node 16a (UPFO) may be regarded as a separate node. Currently, the UPF network node is regarded as a separate node that is exposed. Similarly, the first UPF network node 16a (UPFO) may also be exposed separately. In some embodiments, the combination of the UPF network nodes 16 (UPFO, UPF1 and UPF2) may be exposed as a single router. To achieve this, the first UPF network node 16a (UPFO) may expose its topology to a 5GS entity such as the TSCTSF or TSN AF, which may further expose the topology to an external node as a customer network controller (CNC) or DetNet controller.

[0154] The topology information may include a node identity of the first UPF network node 16a (UPFO) and / or the list of interfaces where the tunneling could be considered as a virtual interface. The interfaces can be assigned an identity, e.g., the identity could be the combination of IP address and tunnel endpoint identifier (TEID). The interfaces can also be assigned virtual addresses (such as virtual IP addresses) even if they are not used in the actual traffic, though it is not required that each tunneling virtual interface has a separate IP address. It may also be indicated that the given interface is a virtual interface. The information can help a central controller in the subsequent configuration, i.e., no need to configure parameters that are only applicable to physical interfaces. The topology information may also include information about the neighbors, i.e., the peer endpoint (including IP address and possibly TEID) of the GTP tunnel may also be provided.

[0155] The first UPF network node 16a (UPFO) can use the already defined port management information container (PMIC) or user plane node management information container (UMIC) to inform a central node, such as the TSCTSF or TSN AF, about a new tunnel (virtual interface). The central node, such as the TSCTSF or TSN AF, may relay the information (possibly in another format, defined by IETF) to a central controller use as a DetNet controller, CNC or other type of SDN controller. In scenarios where the first UPF network node 16a (UPFO) provides topology information, the second and third UPF network nodes 16b, 16c (UPF1 and UPF2) may also provide topology information including the virtual interface (GTP tunnel) between the second and / or third UPF network nodes 16b, 16c (UPF1 and UPF2) and the first UPF network node 16a (UPFO).

[0156] The network may include configuration on whether the topology information related to the first UPF network node 16a (UPFO) is to be exposed or not, or alternatively only the first UPF network node 16a (UPFO) is exposed as a node and the individual second and third UPF network nodes 16b, 16c (UPF1 and UPF2) are not exposed. Possible ways for the configuration include one or more of:

[0157] • This configuration may be in the SMF network nodes 16, and be provided to the UPF network nodes 16;

[0158] • The configuration may be in the UPF network nodes 16 as preconfiguration.

[0159] • The configuration may be in the subscription records and downloaded to the SMF network nodes 16.

[0160] • The configuration may in a central node such as the TSCTSF or TSN AF, and the UPF network nodes 16 may query that central node to whether or not to provide this configuration.

[0161] • Even if the UPF network nodes 16 provide the topology information related to the first UPF network node 16a (UPFO), the TSCTSF or TSN AF (central node) may also contain configuration whether or not to expose such information to a central controller such as the DetNet controller or CNC or other type of SDN controller.

[0162] Besides the exposure of the topology information, the central node (TSCTSF and TSN AF) may also be used to transfer configuration (such as the setup of the PREOF functionality) from a central controller to the first UPF network node 16a (UPFO), and also transfer the response back.

[0163] In some deployments, based on configuration, the central node (TSCTSF or TSN AF) to expose the combination of the UPF network nodes 16 as a single node (router or bridge), so that the internal links - the tunneling between the second UPF network node 16b (UPF1) and / or third UPF network node 16c (UPF2) and the first UPF network node 16a (UPFO)- are hidden. In this case, the central node processes the configuration requests, and splits up to individual configurations corresponding to the individual user plane nodes.

[0164] Mapping of explicit flow routing information

[0165] In the case of DetNet, the central controller (DetNet controller) may provide explicit flow routing information, providing information on the traffic flow and the interface that needs to be used at a given node to forward the traffic. When such explicit flow routing is provided, it may be translated to a 3GPP forwarding rule.

[0166] A central 5GS entity, such as the TSCTSF, may map the DetNet flow routing information, and provide the information e.g., to the SMF handling the traffic (signaling may go via the policy control function (PCF)). For example, the DetNet controller may provide information on which traffic needs to be forwarded from the second UPF network node 16b (UPF1) to the first UPF network node 16a (UPFO) using a filter on the header fields. The TSCTSF may provide this information via the PCF to the second SMF network node 16e (SMF1), which would then configure filtering rules on the second UPF network node 16b (UPF1) to forward the traffic to the first UPF network node 16a (UPFO). In scenarios where the second SMF network node 16e (SMF1) is used for the tunneling between the second UPF network node 16b (UPF1) and the first UPF network node 16a (UPFO), the information may be sent to first SMF network node 16d (SMFO), and similarly for third UPF network node 16c (UPF2).

[0167] Also, similar filtering rules may be provided in the downlink direction. However, in the downlink case, it may be typical that the second UPF network node 16b (UPF1) or the third UPF network node 16c (UPF2) forwards all traffic to a given IP address (or given set of IP addresses or prefixes) downlink on the PDU Session. When the explicit flow routing adds rules for a subset of the traffic, while the requested forwarding is already in place, then there is no need to update the forwarding rules at the second UPF network node 16b (UPF1) or the third UPF network node 16c (UPF2) in the downlink.

[0168] Subsequent addition of UPFO

[0169] Although the first UPF network node 16a (UPFO) may be added during PDU Session Establishment, the embodiments of the present disclosure are not limited as such, e.g., it may also be possible to add the first UPF network node 16a (UPFO) later or before. For example, the first UPF network node 16a (UPFO) may be added after the PDU Sessions have been established. The trigger for adding the first UPF network node 16a (UPFO) may be an external signaling, e.g., via an exposure interface through NEF or TSCTSF, that a new PREOF functionality may be needed. The 5GS system (e.g., in the NEF or TSCTSF node) may determine that a separate first UPF network node 16a (UPFO) is needed and indicate this to the SMF network nodes 16 (possibly via the PCFs). The SMF network nodes 16 may then set up the first UPF network node 16a (UPFO) accordingly.

[0170] As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, computer program product and / or computer storage media storing an executable computer program. Accordingly, the concepts described herein may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a “circuit” or “module.” Any process, step, action and / or functionality described herein may be performed by, and / or associated to, a corresponding module, which may be implemented in software and / or firmware and / or hardware. Furthermore, the disclosure may take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in the medium that can be executed by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD- ROMs, electronic storage devices, optical storage devices, or magnetic storage devices.

[0171] Some embodiments are described herein with reference to flowchart illustrations and / or block diagrams of methods, systems and computer program products. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer (to thereby create a special purpose computer), special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0172] These computer program instructions may also be stored in a computer readable memory or storage medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instruction means which implement the function / act specified in the flowchart and / or block diagram block or blocks.

[0173] The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0174] It is to be understood that the functions / acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality / acts involved. Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

[0175] Computer program code for carrying out operations of the concepts described herein may be written in an object oriented programming language such as Python, Java® or C++. However, the computer program code for carrying out operations of the disclosure may also be written in conventional procedural programming languages, such as the "C" programming language. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user's computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0176] Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments can be combined in any way and / or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.

[0177] It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings and following claims.

Claims

What is claimed is:

1. A method in a session management function, SMF, network node (16) configured to communicate with at least one of a first user plane function, UPF, network node (16a), a second UPF network node (16b), and a third UPF network node (16c), the first UPF network node (16a) being associated with a first packet replication and elimination and ordering function, PREOF, (102a) the method comprising: determining (S100) that at least one of a first packet data unit, PDU, session and a second PDU session is associated with a redundant traffic handling of data packets associated with at least one user equipment, UE, (22) based on at least one of a configuration, subscription information, a UE indication, and a request or response from a control entity; selecting (S102) the first UPF network node (16a) to perform the redundant traffic handling of data packets associated with the at least one UE (22), the first PDU session, and the second PDU session based on the determination, the redundant traffic handling being performed using: the first PREOF (102a); a first tunnel (102a, 104a) associated with the first PDU session, the first tunnel (102a, 104a) being at least between the first UPF network node (16a) and the second UPF network node (16b); and a second tunnel (102b, 104b) associated with the second PDU session, the second tunnel (102b, 104b) being at least between the first UPF network node (16a) and the third UPF network node (16c); and causing (S104) the first UPF network node (16a) to perform the redundant traffic handling.

2. The method of Claim 1, wherein performing the redundant traffic handling includes: performing an action associated with the first PREOF (102a).

3. The method of any one of Claims 1 and 2, wherein the method further includes: receiving an indication indicating at least one of:whether at least one of the first PDU session and the second PDU session is associated with the redundant traffic handling; and whether one UPF network node (16) is needed for the redundant traffic handling.

4. The method of any one of Claims 1-3, wherein the selection of the first UPF network node (16a) is based on at least one of a data network name, DNN, and single network slice selection assistance information, S -NS SAI.

5. The method of any one of Claims 1-4, wherein the method further includes: establishing the first tunnel (102a, 104a) at least between the first UPF network node (16a) and the second UPF network node (16b) and the second tunnel (102b, 104b) at least between the first UPF network node (16a) and the third UPF network node (16c), the second UPF network node (16b) being configured as a first PDU session anchor, the third UPF network node (16c) being configured as a second PDU session anchor.

6. The method of Claim 5, wherein the first tunnel (102a, 104a) and the second tunnel (102b, 104b) are each a general packet radio services, GPRS, tunnelling protocol, GTP, tunnel.

7. The method of any one of Claims 5 and 6, wherein the method further includes: determining a first tunnel (102a, 104a) endpoint of the first tunnel (102a, 104a) at the second UPF network node (16b); determining a second tunnel (102b, 104b) endpoint of the second tunnel (102b, 104b) at the third UPF network node (16c); establishing a first tunnel (102a, 104a) forwarding from the second UPF network node (16b) to the first UPF network node (16a); and establishing a second tunnel (102b, 104b) forwarding from the third UPF network node (16c) to the first UPF network node (16a).

8. The method of Claim 7, wherein the method further includes:updating the first tunnel (102a, 104a) endpoint and the second tunnel (102b, 104b) endpoint to establish forwarding from the first UPF network node (16a) to the second UPF network node (16b) and the third UPF network node (16c), respectively.

9. The method of any one of Claims 1-8, wherein the at least one UE (22) is associated with a second PREOF (102b), and the method further includes: establishing the first tunnel (102a, 104a) and the second tunnel (102b, 104b) between the first PREOF (102a) and the second PREOF (102b) via the first UPF network node (16a).

10. The method of any one of Claims 1-9, wherein the selection of the first UPF network node (16a) is further based on a query to a database network node (16k).

11. The method of any one of Claims 1-10, wherein the method further includes: configuring filtering rules for the first UPF network node (16a) and the second UPF network node (16b) to separate traffic to be tunneled to the first UPF network node (16a).

12. The method of any one of Claims 1-11, wherein the SMF network node (16) is: a first SMF network node (16d) configured to manage the first PDU session and the second PDU session; a second SMF network node (16e) configured to manage the first PDU session; or a third SMF network node (16f) configured to manage the second PDU session.

13. The method of Claim 12, wherein the method further includes: when the SMF network node (16) is configured to manage the first PDU session and the second PDU session, receiving identity information of the second UPF network node (16b) and the third UPF network node (16c) to identify traffic assigned to the first PDU session and the second PDU session.

14. A session management function, SMF, network node (16) configured to communicate with at least one of a first user plane function, UPF, network node (16a), a second UPF network node (16b), and a third UPF network node (16c), the first UPF network node (16a) being associated with a first packet replication and elimination and ordering function, PREOF (102a), the SMF network node (16) being configured to: determine that at least one of a first packet data unit, PDU, session and a second PDU session is associated with a redundant traffic handling of data packets associated with at least one user equipment, UE, (22) based on at least one of a configuration, subscription information, a UE indication, and a request or response from a control entity; select the first UPF network node (16a) to perform the redundant traffic handling of data packets associated with the at least one UE (22), the first PDU session, and the second PDU session based on the determination, the redundant traffic handling being performed using: the first PREOF (102a); a first tunnel (102a, 104a) associated with the first PDU session, the first tunnel (102a, 104a) being at least between the first UPF network node (16a) and the second UPF network node (16b); and a second tunnel (102b, 104b) associated with the second PDU session, the second tunnel (102b, 104b) being at least between the first UPF network node (16a) and the third UPF network node (16c); and cause the first UPF network node (16a) to perform the redundant traffic handling.

15. The SMF network node (16) of Claim 14, wherein performing the redundant traffic handling includes: performing an action associated with the first PREOF (102a).

16. The SMF network node (16) of any one of Claims 14 and 15, wherein the SMF network node (16) is further configured to: receive an indication indicating at least one of: whether at least one of the first PDU session and the second PDU session is associated with the redundant traffic handling; andwhether one UPF network node (16) is needed for the redundant traffic handling.

17. The SMF network node (16) of any one of Claims 14-16, wherein the selection of the first UPF network node (16a) is based on at least one of a data network name, DNN, and single network slice selection assistance information, S-NSSAI.

18. The SMF network node (16) of any one of Claims 14-17, wherein the SMF network node (16) is further configured to: establish the first tunnel (102a, 104a) at least between the first UPF network node (16a) and the second UPF network node (16b) and the second tunnel (102b, 104b) at least between the first UPF network node (16a) and the third UPF network node (16c), the second UPF network node (16b) being configured as a first PDU session anchor, the third UPF network node (16c) being configured as a second PDU session anchor.

19. The SMF network node (16) of Claim 18, wherein the first tunnel (102a, 104a) and the second tunnel (102b, 104b) are each a general packet radio services, GPRS, tunnelling protocol, GTP, tunnel.

20. The SMF network node (16) of any one of Claims 18 and 19, wherein the SMF network node (16) is further configured to: determine a first tunnel (102a, 104a) endpoint of the first tunnel (102a, 104a) at the second UPF network node (16b); determine a second tunnel (102b, 104b) endpoint of the second tunnel (102b, 104b) at the third UPF network node (16c); establish a first tunnel (102a, 104a) forwarding from the second UPF network node (16b) to the first UPF network node (16a); and establish a second tunnel (102b, 104b) forwarding from the third UPF network node (16c) to the first UPF network node (16a).

21. The SMF network node (16) of Claim 20, wherein the SMF network node (16) is further configured to:update the first tunnel (102a, 104a) endpoint and the second tunnel (102b, 104b) endpoint to establish forwarding from the first UPF network node (16a) to the second UPF network node (16b) and the third UPF network node (16c), respectively.

22. The SMF network node (16) of any one of Claims 14-21, wherein the at least one UE (22) is associated with a second PREOF (102b), and the SMF network node (16) is further configured to: establish the first tunnel (102a, 104a) and the second tunnel (102b, 104b) between the first PREOF (102a) and the second PREOF (102b) via the first UPF network node (16a).

23. The SMF network node (16) of any one of Claims 14-22, wherein the selection of the first UPF network node (16a) is further based on a query to a database network node (16j).

24. The SMF network node (16) of any one of Claims 14-23, wherein the SMF network node (16) is further configured to: configure filtering rules for the first UPF network node (16a) and the second UPF network node (16b) to separate traffic to be tunneled to the first UPF network node (16a).

25. The SMF network node (16) of any one of Claims 14-24, wherein the SMF network node (16) is: a first SMF network node (16d) configured to manage the first PDU session and the second PDU session; a second SMF network node (16e) configured to manage the first PDU session; or a third SMF network node (16f) configured to manage the second PDU session.

26. The SMF network node (16) of Claim 25, wherein the SMF network node (16) is further configured to: when the SMF network node (16) is configured to manage the first PDU session and the second PDU session, receive identity information of the second UPF networknode (16b) and the third UPF network node (16c) to identify traffic assigned to the first PDU session and the second PDU session.

27. A method in a first user plane function, UPF, network node (16a) configured to communicate with a second UPF network node (16b), a third UPF network node (16c), and at least one user equipment, UE, (22) the first UPF network node (16a) being different from at least one of the second UPF network node (16b) and the third UPF network node (16c), the first UPF network node (16a) being associated with a first packet replication and elimination and ordering function, PREOF (102a), the method comprising: performing (S106) redundant traffic handling of data packets associated with the at least one UE (22), a first packet data unit, PDU, session, and a second PDU session, the redundant traffic handling being performed using: the first PREOF (102a); a first tunnel (102a, 104a) associated with the first PDU session, the first tunnel (102a, 104a) being at least between the first UPF network node (16a) and the second UPF network node (16b); and a second tunnel (102b, 104b) associated with the second PDU session, the second tunnel (102b, 104b) being at least between the first UPF network node (16a) and the third UPF network node (16c).

28. The method of Claim 27, wherein performing the redundant traffic handling includes: performing an action associated with the first PREOF (102a).

29. The method of any one of Claims 27 and 28, wherein the first UPF network node (16a) is selected by a session management function, SMF, network node to perform the redundant traffic handling based on at least one of a data network name, DNN, and single network slice selection assistance information, S-NSSAI.

30. The method of any one of Claims 27-29, wherein the second UPF network node (16b) is configured as a first PDU session anchor, and the third UPF network node (16c) is configured as a second PDU session anchor.

31. The method of any one of Claims 27-30, wherein the first tunnel (102a, 104a) and the second tunnel (102b, 104b) are each a general packet radio services, GPRS, tunnelling protocol, GTP, tunnel.

32. The method of any one of Claims 27-31, wherein: the first tunnel (102a, 104a) has a first tunnel (102a, 104a) endpoint at the second UPF network node (16b); the second tunnel (102b, 104b) has a second tunnel (102b, 104b) endpoint at the third UPF network node (16c); a first tunnel (102a, 104a) forwarding is established from the second UPF network node (16b) to the first UPF network node (16a); and a second tunnel (102b, 104b) forwarding is established from the third UPF network node (16c) to the first UPF network node (16a).

33. The method of Claim 32, wherein the first tunnel (102a, 104a) endpoint and the second tunnel (102b, 104b) endpoint are updated to establish forwarding from the first UPF network node (16a) to the second UPF network node (16b) and the third UPF network node (16c), respectively.

34. The method of any one of Claims 27-33, wherein the at least one UE (22) is associated with a second PREOF (102b), and the method further includes: at least one of transmitting and receiving the data packets via the first tunnel (102a, 104a) and the second tunnel (102b, 104b) between the first PREOF (102a) and the second PREOF (102b).

35. A first user plane function, UPF, network node (16a) configured to communicate with a second UPF network node (16b), a third UPF network node (16c), and at least one user equipment, UE, the first UPF network node (16a) being different from at least one of the second UPF network node (16b) and the third UPF network node (16c), the first UPF network node (16a) being associated with a first packet replication and elimination and ordering function, PREOF (102a), the first UPF network node (16a) being configured to:perform redundant traffic handling of data packets associated with the at least one UE (22), a first packet data unit, PDU, session, and a second PDU session, the redundant traffic handling being performed using: the first PREOF (102a); a first tunnel (102a, 104a) associated with the first PDU session, the first tunnel (102a, 104a) being at least between the first UPF network node (16a) and the second UPF network node (16b); and a second tunnel (102b, 104b) associated with the second PDU session, the second tunnel (102b, 104b) being at least between the first UPF network node (16a) and the third UPF network node (16c).

36. The first UPF network node (16a) of Claim 35, wherein performing the redundant traffic handling includes: performing an action associated with the first PREOF (102a).

37. The first UPF network node (16a) of any one of Claims 35 and 36, wherein the first UPF network node (16a) is selected by a session management function, SMF, network node to perform the redundant traffic handling based on at least one of a data network name, DNN, and single network slice selection assistance information, S-NSSAI.

38. The first UPF network node (16a) of any one of Claims 35-37, wherein the second UPF network node (16b) is configured as a first PDU session anchor, and the third UPF network node (16c) is configured as a second PDU session anchor.

39. The first UPF network node (16a) of any one of Claims 35-38, wherein the first tunnel (102a, 104a) and the second tunnel (102b, 104b) are each a general packet radio services, GPRS, tunnelling protocol, GTP, tunnel.

40. The first UPF network node (16a) of any one of Claims 35-39, wherein: the first tunnel (102a, 104a) has a first tunnel (102a, 104a) endpoint at the second UPF network node (16b); the second tunnel (102b, 104b) has a second tunnel (102b, 104b) endpoint at the third UPF network node (16c);a first tunnel (102a, 104a) forwarding is established from the second UPF network node (16b) to the first UPF network node (16a); and a second tunnel (102b, 104b) forwarding is established from the third UPF network node (16c) to the first UPF network node (16a).

41. The first UPF network node (16a) of Claim 40, wherein the first tunnel (102a, 104a) endpoint and the second tunnel (102b, 104b) endpoint are updated to establish forwarding from the first UPF network node (16a) to the second UPF network node (16b) and the third UPF network node (16c), respectively.

42. The first UPF network node (16a) of any one of Claims 35-41, wherein the at least one UE (22) is associated with a second PREOF (102b), and first UPF network node (16a) is further configured to: at least one of transmit and receive the data packets via the first tunnel (102a, 104a) and the second tunnel (102b, 104b) between the first PREOF (102a) and the second PREOF (102b).

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