WO2020197451A1

WO2020197451A1 - Methods and devices for connecting a wireless communication device to a user plane in a wireless communication network

Info

Publication number: WO2020197451A1
Application number: PCT/SE2019/050267
Authority: WO
Inventors: Jari Vikberg; Göran HALL; Ulf Mattsson; Gunnar Mildh; Göran RUNE
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2019-03-25
Filing date: 2019-03-25
Publication date: 2020-10-01

Abstract

A network node ( ₂₂8 ) configured to connect a wireless communication device ( ₂₁₀) to a user plane in a wireless communication network ( ₂₀₀ ) in which the network node ( ₂₂8 ) is arranged is provided, the network node ( ₂₂8 ) comprising a processing unit ( ₁₁₅) and a memory ( ₁₁₇), said memory containing instructions ( ₁₁ 6 ) executable by said processing unit, whereby the network node ( ₂₂ 8 ) is operative to provide core network user plane functionality, provide radio access network user plane functionality, the network node ( ₂₂8 ) further being arranged with a first direct interface to a core network control plane function ( ₂₂₂) configured to provide session management via which the core network user plane functionality is configured and a second direct interface to a radio access network control plane function ( ₂₂₅) via which the radio access network user plane functionality is configured

Description

METHODS AND DEVICES FOR CONNECTING A WIRELESS COMMUNICATION DEVICE TO A USER PLANE IN A WIRELESS COMMUNICATION NETWORK

TECHNICAL FIELD

The invention relates to methods of connecting a wireless communication device to a user plane in a wireless communication network, and devices performing the methods.

BACKGROUND

Now, 3rd Generation Partnership Project (3GPP) is standardizing a fifth generation (5G) Core Network (CN), being referred to as 5GC, and Next Generation Radio Access Network (NG-RAN).

Figure 1 shows a 5G wireless communication network 100 as depicted in 3GPP TS 23.501 comprising a User Equipment (UE, 110) in the form of for instance a mobile phone, tablet, smart phone, Internet-of-Things (IoT) sensor, etc., connecting to a (Radio) Access Network ((R)AN, 111), and to a Data Network (DN, 113) via a User Plane Function (UPF, 112). The UPF is a service function that processes user plane packets; processing may include altering the packet’s payload and/or header, interconnection to data network(s), packet routing and forwarding, etc. Further, the network is shown to comprise a Network Slice Selection Function (NSSF, 114) for handling network slicing, a Network Exposure Function (NEF, 115) for exposing capabilities and events, an NF (Network Function) Repository Function (NRF, 116) for providing discovery and registration functionality for NFs, a Policy Control Function (PCF, 117), Unified Data Management (UDM, 118) for storing subscriber data and profiles, and an Application Function (AF, 119) for supporting specific applications and optionally application influence on traffic routing.

Moreover, the network is shown to comprise an Authentication Server Function (AUSF, 120) for storing data for authentication of UE, a core network control plane function configured to provide mobility management in the form of an Access and Mobility Function (AMF, 121) for providing UE- based authentication, authorization, mobility management, etc., and a core network control plane function configured to provide session management in the form of a Session Management Function (SMF, 122) configured to perform session management, e.g. session establishment, modify and release, etc.

Figure 2 illustrates a prior art 5G wireless communication network 100 in a different view illustrating a radio base station 124, a so called Next

Generation NodeB (gNB), forming part of the NG-RAN. The gNB 124 comprises a radio access network control plane function in the form of a Central Unit Control Plane (CU-CP, 125), a radio access network user plane function in the form of a Central Unit User Plane (CU-UP, 126) and a

Distributed Unit (DU, 127) for connecting the NG UE no to the control plane and the user plane, respectively, which is referred to as a High Layer Split (HLS). The gNB provides NR control and user plane terminations towards the UE, and is connected via NG-C/N2 and NG-U/N3 interfaces to the 5GC. Further, the NG-RAN may comprise Long Term Evolution (LTE) base stations, referred to as ng-eNBs. The CU-CP 125 hosts the Radio Resource Control (RRC) protocol and the Packet Data Convergence Protocol (PDCP) protocol used for control plane, while the CU-UP 126 hosts the Service Data Adaptation Protocol (SDAP) protocol and the PDCP protocol used for user plane. The CU-CP 125 is controlling the CU-UP 126 via an El interface. As shown in Figure 2, the CU-CP 125 is the function that terminates an N2 interface from the AMF 121 in the 5GC, and the CU-UP 126 is the function terminating an N3 interface from the UPF 112b in the 5GC. Logically, the NG UE no has one CU-UP 126 configured per PDU session.

The SMF 122 connects to UPFs 112a, 112b via the N4 interface and to the AMF 121 via the Nil interface. The Nil interface can alternatively be realized using service-based interfaces utilized by the AMF 121 and SMF 122, i.e.

Namf and Nsmf, respectively.

Figure 2 illustrates that the network 100 comprises a plurality of UPFs 112a, 112b, but it is also envisaged that the UPF 112b connecting the NG UE 110 to a local service network 123 via local breakout is omitted, in which case the interface N3 extends between the CU-UP 126 and the UPF 112a.

A problem with this structure is that it results in inefficient user plane handling with multiple different user plane related functions, i.e. DU, CU-UP and one or more UPFs. SUMMARY

An object of the present invention is to solve, or at least mitigate this problem in the art, and thus to provide an improved method of connecting a wireless communication device to a user plane in a wireless communication network.

This object is attained in a first aspect by a network node configured to connect a wireless communication device to a user plane in a wireless communication network in which the network node is arranged. The network node comprises a processing unit and a memory, said memory containing instructions executable by said processing unit, whereby the network node is operative to provide core network user plane functionality, and provide radio access network user plane functionality; the network node further being arranged with a first direct interface to a core network control plane function configured to provide session management via which the core network user plane functionality is configured and a second direct interface to a radio access network control plane function via which the radio access network user plane functionality is configured.

This object is attained in a second aspect of the invention by a method performed by the network node of the first aspect for enabling establishment of user plane connectivity for a wireless communication device with a wireless communication network. The method comprises receiving, from the radio access network control plane function via the second direct interface, configuration data arranged to configure the provided radio access network user plane functionality, the configuration data having been prepared at the radio access network control plane function, configuring the radio access network user plane functionality based on the received configuration data prepared at the radio access network control plane function, allocating an address for the network node and creating a core network user plane context information and a reference to the created core network user plane context information, the address being configured to designate the network node via the first interface, transmitting the reference to the created core network user plane context information and information identifying the allocated address, to the radio access network control plane function via the second direct interface, for further transfer to the core network control plane function configured to provide session management, receiving, from the core network control plane function configured to provide session management via the first direct interface, configuration data arranged to configure the provided core network user plane functionality and the reference to the created core network user plane context information, configuring the created core network user plane context information based on the received configuration data prepared at the core network control plane function configured to provide session management, the created core network user plane context information being identified by the received reference to the created core network user plane context information, wherein the providing of the core network user plane functionality of the network node is enabled and establishing the user plane connectivity with the wireless communication device.

This object is attained in a third aspect of the invention by a method performed by the network node of the first aspect for enabling establishment of user plane connectivity for a wireless communication device with a wireless communication network. The method comprises receiving, from the core network control plane function configured to provide session

management via the first direct interface, configuration data arranged to configure the provided core network user plane functionality, the configuration data having been prepared at the core network control plane function, configuring the core network user plane functionality based on the received configuration data prepared at the core network control plane function, allocating an address for the network node and creating a radio access network user plane context information and a reference to the created radio access network user plane context information, the address being configured to designate the network node via the second interface, transmitting the reference to the created radio access network user plane context information and information identifying the allocated address, to the core network control plane function configured to provide session

management via the first direct interface, for further transfer to the radio access network control plane function, receiving, from the radio access network control plane function via the second direct interface, configuration data arranged to configure the provided radio access network user plane functionality and the reference to the created radio access network user plane context information, configuring the created radio access network user plane information based on the received configuration data prepared at the radio access network control plane function, the created radio access network user plane functionality being identified by the received reference to the created radio access network user plane context information, wherein the providing of the radio access network user plane functionality of the network node is enabled, and establishing the user plane connectivity with the wireless communication device.

This object is attained in a fourth aspect of the invention by a core network control plane function configured to provide session management for enabling establishment of user plane connectivity for a wireless

communication device with a wireless communication network, the core network control plane function configured to provide session management comprising a processing unit and a memory, said memory containing instructions executable by said processing unit, whereby the core network control plane function configured to provide session management is operative to receive, from a core network control plane function configured to provide mobility management, a request to establish user plane connectivity for a wireless communication device, select a network node providing core network user plane functionality and radio access network user plane functionality, prepare configuration data arranged to configure core network user plane functionality of the selected network node providing said core network user plane functionality and radio access network user plane functionality, and to transmit, to the network node via a direct interface, the configuration data to the network node.

This object is attained in a fifth aspect of the invention by a method

performed by a core network control plane function configured to provide session management for enabling establishment of user plane connectivity for a wireless communication device with a wireless communication network. The method comprises receiving, from a core network control plane function configured to provide mobility management, a request to establish user plane connectivity for a wireless communication device, selecting a network node providing core network user plane functionality and radio access network user plane functionality, preparing configuration data arranged to configure core network user plane functionality of the selected network node providing said core network user plane functionality and radio access network user plane functionality, and transmitting, to the network node via a direct interface, the configuration data to the network node.

This object is attained in a sixth aspect of the invention by a core network control plane function configured to provide session management for enabling establishment of user plane connectivity for a wireless

communication device with a wireless communication network, the core network control plane function configured to provide session management comprising a processing unit and a memory, said memory containing instructions executable by said processing unit, whereby the core network control plane function configured to provide session management is operative to receive, from a core network control plane function configured to provide mobility management, a reference to a core network user plane context information prepared at a network node providing core network user plane functionality and radio access network user plane functionality and information identifying an allocated address to the network node, prepare configuration data arranged to configure core network user plane

functionality of the network node identified by the received address information, and to transmit, to the network node via a direct interface, the prepared configuration data arranged to configure the core network user plane functionality of the network node and the reference to a core network user plane context information.

This object is attained in a seventh aspect of the invention by a method performed by a core network control plane function configured to provide session management for enabling establishment of user plane connectivity for a wireless communication device with a wireless communication network. The method comprises receiving, from a core network control plane function configured to provide mobility management, a reference to a core network user plane context information prepared at a network node providing core network user plane functionality and radio access network user plane functionality and information identifying an allocated address to the network node, prepare configuration data arranged to configure core network user plane functionality of the network node identified by the received address information, and transmitting, to the network node via a direct interface, the prepared configuration data arranged to configure the core network user plane functionality of the network node and the reference to a core network user plane context information.

This object is attained in a eighth aspect of the invention by a radio access network control plane function for enabling establishment of user plane connectivity for a wireless communication device with a wireless

communication network, the radio access network control plane function comprising a processing unit and a memory, said memory containing instructions executable by said processing unit, whereby the radio access control network control plane function is operative to receive, from a core network control plane function configured to provide session management, a request to establish user plane connectivity for a wireless communication device, select a network node providing core network user plane functionality and radio access network user plane functionality, preparing configuration data arranged to configure radio access network user plane functionality of the selected network node providing core network user plane functionality and said radio access network user plane functionality, and to transmit, to the selected network node providing core network user plane functionality and radio access network user plane functionality via a direct interface, the prepared configuration data.

This object is attained in a ninth aspect of the invention by a method performed by a radio access network control plane function for enabling establishment of user plane connectivity for a wireless communication device with a wireless communication network. The method comprises receiving, from a core network control plane function configured to provide session management, a request to establish user plane connectivity for a wireless communication device, selecting a network node providing core network user plane functionality and radio access network user plane functionality, preparing configuration data arranged to configure radio access network user plane functionality of the selected network node providing core network user plane functionality and said radio access network user plane functionality, and transmitting, to the selected network node providing core network user plane functionality and radio access network user plane functionality via a direct interface, the prepared configuration data.

This object is attained in a tenth aspect of the invention by a radio access network control plane function for enabling establishment of user plane connectivity for a wireless communication device with a wireless

communication network, the radio access network control plane function comprising a processing unit and a memory, said memory containing instructions executable by said processing unit, whereby the radio access control network control plane function is operative to receive, from a core network control plane function configured to provide session management, a request to establish user plane connectivity for a wireless communication device, the request comprising a reference to a radio access network user plane context information prepared at a network node providing radio access network user plane functionality and core network user plane functionality, and information identifying an allocated address to the network node, prepare configuration data arranged to configure radio access network user plane functionality of the network node identified by the received address information, and to transmit the prepared configuration data arranged to configure the radio access network user plane functionality and the reference to a radio access network user plane context information to the network node via a direct interface. This object is attained in a eleventh aspect of the invention by a method performed by a radio access network control plane function for enabling establishment of user plane connectivity for a wireless communication device with a wireless communication network. The method comprises receiving, from a core network control plane function configured to provide session management, a request to establish user plane connectivity for a wireless communication device, the request comprising a reference to a radio access network user plane context information prepared at a network node providing radio access network user plane functionality and core network user plane functionality, and information identifying an allocated address to the network node, prepare configuration data arranged to configure radio access network user plane functionality of the network node identified by the received address information, and transmitting the prepared configuration data arranged to configure the radio access network user plane functionality and the reference to a radio access network user plane context information to the network node via a direct interface.

Hence, in some aspects, a network node referred to herein as a Combined RAN and CN User Plane Function (CRC-UPF) is introduced in which UPF functionality and CU-UP functionality are integrated.

Hence, the CRC-UPF hosts the SDAP protocol and the user plane part of the PDCP protocol. The CU-CP may control the CU-UP functionality of the CRC- UPF via a direct El interface, while the SMF may control the UPF

functionality of the CRC-UPF via a direct N4 interface.

The CRC-UPF advantageously enables removal of the user plane tunnel between 5GC and NG-RAN as the N3 interface becomes an internal interface in the CRC-UPF. Further, with the CRC-UPF user plane latency is reduced.

Advantageously, embodiments described herein enables reuse of the existing interfaces N4 (i.e. a first direct interface to the SMF) and El (i.e. a second direct interface to the CU-CP) with small additions or modifications, thereby enabling the deployment of a CRC-UPF without the need to define new interfaces or tunnel one interface over the other. This reduces the overall system complexity and costs for deploying CRC-UPFs.

Various embodiments will be discussed in the following.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 shows a prior art 5G wireless communication network;

Figure 2 illustrates a prior art 5G wireless communication network in a different view;

Figure 3 shows a signalling diagram illustrating establishment of a

communication session for a wireless communication device in the prior art 5G communication network of Figure 2; Figure 4 illustrates a 5G communication network implementing a network node configured to connect a wireless communication device to a user plane in the network according to an embodiment;

Figure 5 shows a signalling diagram illustrating a method of an embodiment; Figure 6 shows a signalling diagram illustrating a method of a further embodiment;

Figure 7 shows a signalling diagram illustrating a method of yet a further embodiment;

Figure 8 shows a signalling diagram illustrating a method of still a further embodiment;

Figure 9 illustrates a 5G communication network implementing a network node configured to connect a wireless communication device to a user plane in the network according to another embodiment;

Figure 10 shows a CRC-UPF according to an embodiment; Figure 11 shows an SMF according to an embodiment; and

Figure 12 shows a CU-CP according to an embodiment.

DETAILED DESCRIPTION

Embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments are shown. The disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like numbers refer to like elements throughout the description.

Figure 1 shows a prior art 5G wireless communication network having been previously discussed. Figure 2 illustrates a prior art 5G wireless communication network in a different view, also having been previously discussed.

Figure 3 shows a signalling diagram illustrating establishment of Packet Data Unit (PDU) session for an NG UE 110 in the prior art 5G communication network 100 previously described with reference to Figure 2.

In a first step S101, the NG UE 110 sends a request for establishment of a PDU session to the AMF 121 which in step S102 selects an SMF 122 via which the PDU session will be managed.

In step S103, the AMF 121 sends the PDU session request to the selected SMF 122, which transmits a response message back to the AMF 121 in step S104 before carrying through a PDU Session authentication/authorization procedure with the NG UE 110 in step S105.

If the SMF 122 successfully authenticates the NG UE 110, a UPF 112 is selected in step S106, via which the NG UE 110 will connect to the user plane of the network 100. The SMF 122 sends an N4 session establishment request to the selected UPF 112 in step S107, and the UPF 112 sends a response accordingly in step S108 comprising for instance an UPF transport address and an UPF Tunnel Endpoint Identifier (TEID).

The SMF 122 will in its turn forward the received data to the AMF 121 in step S109, which sends a request to the CU-CP 125 in step S110 to setup PDU session resources for the PDU session to be established, the request comprising the UPF transport address and the UPF TEID.

The CU-CP 125 selects a CU-UP 126 in step S111 via which the PDU session is to be established with the UPF 112, and a request to this effect is sent to the selected CU-UP 126 in step S112, which responds in step S113 with a CU-UP establishment response comprising for instance a CU-UP transport address and a CU-UP TEID.

Thereafter, the CU-CP 125 performs an AN resources setup procedure with the NG UE no in step S114 (the DU can also be configured in relation to this step) and sends a setup PDU session resources response (to the message received in step S110) to the AMF 121 containing the CU-UP transport address and the CU-UP TEID in step S115. The AMF 121 will in its turn send a message comprising the CU-UP transport address and the CU-UP TEID to the SMF 122 in step S116, which sends the CU-UP transport address and the CU-UP TEID to the UPF 112 in step S117.

Finally, in step S118, the PDU session is established with a user plane between the NG UE 110, the DU 127, the CU-UP 126 and the UPF 112.

As described with reference to Figure 3, the UPF 112 and CU-UP 126 are selected independently of each other and these functions are also configured using separate interfaces, i.e. the UPF 112 is configured by the SMF 122 using the N4 interface and the CU-UP 126 is configured by the CU-CP 125 using the Ei interface. Figure 3 shows a scenario where a single UPF 112 is selected by the SMF 122. The SMF 122 may also select multiple UPFs 112a, 112b connected via N9 interface as shown in Figure 2.

The separation of 5GC UPF 112 and NG-RAN CU-UP 126 functions has its reasons; e.g. that different domains control their own functionality (in 3GPP, in the operator community and in the vendor community). The separation does however include user plane efficiency aspects as each user plane PDU needs to traverse through both 5GC UPF 112 and NG-RAN CU-UP 126 functions, and a possible transport network between these functions. This creates unnecessary user plane latency. This is particularly apparent in a scenario where both 5GC UPF 112 and NG-RAN CU-UP 126 would be virtualized and run on a same virtualization platform on different virtual machines or containers (as each user plane PDU must pass via the

virtualization platform between the different user plane functions).

Further, as can be concluded from the signalling diagram of Figure 3, establishing a PDU session in a 5G network requires quite a few rounds of signalling, as user plane functions are selected and configured separately and also in sequence, i.e. 5GC UPF 112 is selected first followed by selection of NG-RAN CU-UP 126.

Figure 4 illustrates a 5G communication network 200 implementing a network node 228 configured to connect a wireless communication device 210 (i.e. the NG UE) to a user plane in the network 200.

In the following, the network node 228 will be referred to as a Combined RAN and CN User Plane Function (CRC-UPF).

As is shown in Figure 4, the NG-RAN comprises a CU-CP 225 hosting the RRC protocol and the PDCP protocol used for control plane. The CU-CP 225 connects to an AMF 221 via the N2 interface and further to the SMF 222 via the Nil interface, and to a DU 227 via an Fi-C interface, which DU 227 is responsible for connecting the NG UE 210 to the control plane via interface Fi-C and to the user plane via interface Fi-U. The Nil interface can alternatively be realized using service-based interfaces utilized by the AMF 221 and SMF 222, i.e. Namf and Nsmf, respectively.

As can be seen, the UPF functionality and CU-UP functionality is integrated within the CRC-UPF 228. Hence, the CRC-UPF 228 hosts the SDAP protocol and the PDCP protocol used for user plane. The CU-CP 225 may control the CU-UP functionality of the CRC-UPF via the El interface. Further, the CRC- UPF 228 connects to the SMF 222 via the N4 interface, over which the UPF functionality of the CRC-UPF 228 maybe controlled. The CRC-UPF 228 connects to data network 213 via an N6 interface (and possibly also via an N9 interface in case multiple UPFs are used, as discussed hereinabove).

The CRC-UPF 228 advantageously enables removal of the user plane tunnel between 5GC and NG-RAN as the N3 interface becomes an internal interface in the CRC-UPF 228. Further, with the CRC-UPF 228 user plane latency is reduced.

Advantageously, embodiments described herein enables reuse of the existing interfaces N4 (i.e. a first direct interface to the SMF 222) and El (i.e. a second direct interface to the CU-CP 225) with small additions or modifications, thereby enabling the deployment of a CRC-UPF 228 without the need to define new interfaces or tunnel one interface over the other. This reduces the overall system complexity and costs for deploying CRC-UPFs. The selection of the CRC-UPF 228 could be based on local conditions in the domain that performs the selections leading to optimal selection of the CRC- UPF 228 considering multiple factors, such as: a) the RAN could select the CRC-UPF 228 (as illustrated in Figure 5) based on knowledge about UE mobility patterns or QoS characteristics related to ongoing or active or allowed PDU sessions or slices or bearers. The selection could also be based on the availability of RAN processing resources, for example processing resources for Packet Data Convergence Protocol (PDCP), and b) The CN could select the CRC-UPF 228 (as illustrated in Figure 6) based on knowledge on UE services or subscription or charging or policy aspects. It could also be based on knowledge of the transport topology or need for local services.

The solutions also allow selecting different CRC-UPF(s) for different PDU sessions, bearers, slices, services, etc., thereby enabling the operator to optimize the configuration or deployment of the CRC-UPF based on the needs and advantageously reduces user plane latency. Information about the selected CRC-UPF 228 for a given PDU session (or for a group or all PDU sessions) is provided to the other domain (e.g. when the CRC-UPF 228 is selected by CU-UP 225, then information is provided to SMF 222 and vice versa). The information provided consists of interface address for the selected CRC-UPF 228 (could be Transport Network Address (TNL) incl. L3(IP) address, L2 address, protocol ports etc.) and a reference to an user plane context information (e.g. when the CRC-UPF 228 is selected by the CU-CP 225 then the interface address information is for the N4 interface termination in the CRC-UPF 228 selected by CU-CP 225 and the reference to an user plane context information indicates the user plane context in the UPF part of the CRC-UPF 228 to be configured via N4 interface). The reference to an user plane context could include any numerical value, 3GPP defined UE identifiers IMSI, SUPI (subscriber permanent identifier), SUCI (subscriber concealed identifier), or an identifier allocated for a certain node or interface such as AMF UE NGAP ID or RAN UE NGAP ID used on NG/N2 interface, or gNB- CU-CP UE EiAP ID or gNB-CU-UP UE ElAP ID used over El interface, or CP F-SEID or UP F-SEID used over N4 interface.

When the information is received, it is used to configure the other part of the CRC-UPF 228 (e.g. when information is received by the SMF 222, the SMF 222 uses the received N4 interface address and the reference to an user plane context information to configure the UPF part of the CRC-UPF 228).

With reference to Figure 4, in this embodiment, the CU-CP 225 performs the selection of the CRC-UPF 228 and provides the control interface to the CRC- UPF 228 via the El interface to configure the CU-UP part of the CRC-UPF 228. The SMF 222 configures the UPF part of the CRC-UPF 228 via a direct N4 interface based on information about the selected CRC-UPF 228 from the CU-CP 225. It should be noted that the Nil interface is used as an example only, and may alternatively be realized using service-based interfaces exhibited by the AMF 221 and the SMF 222, i.e. Namf and Nsmf, respectively.

Figure 4 shows the overall architecture for single UPF case, i.e. there is a single UPF as the UPF part of the CRC-UPF. In this case the CRC-UPF 228 supports any N6 interface to Data Network(s). Multiple UPFs may also be envisaged, i.e. embodied by the UPF part of the CRC-UPF 228 and one or more standalone UPFs. In such a scenario, the CRC-UPF 228 may support both N6 and N9 interfaces. The different arrangements of UPFs are per UE PDU session, i.e. different UE PDU sessions may use either CRC-UPF with N6 or N9 interface. It is also possible that some PDU sessions for a UE are using normal UPFs, e.g. as shown in Figures 1 and 2 and simultaneously a CRC-UPF (with either N6 or N9) is used for another UE PDU Session. Figure 5 shows a signalling diagram illustrating establishment of a PDU session for the NG UE 210 in the 5G communication network 200 of Figure 4 according to an embodiment, where the CU-CP 225 performs the selection of the CRC-UPF 228. The first five steps S301-S305 of the PDU session establishment process are identical to the first five steps S101-S105 as illustrated in Figure 3.

Hence, in a first step S301, the NG UE 210 sends a request for establishment of a PDU session to the AMF 221 which in step S302 selects an SMF 222 via which the PDU session will be managed. In step S303, the AMF 221 sends the PDU session request to the selected SMF 222, which transmits a response message back to the AMF 221 in step S304 before carrying through a PDU session authentication/authorization procedure with the NG UE 210 in step S305.

In this embodiment, if the SMF 222 successfully authenticates the NG UE 210, it does not select a UPF (i.e. in this scenario the UPF of the CRC-UPF

228) and thus refrains from preparing a data container comprising configuration data for configuring UPF functionality in the CRC-UPF 228.

However, the SMF 222 sends a message for subsequently enabling

establishment of a communication session with the UE 210 to the AMF 221 in step S307 over the Nil interface, which sends a request to the CU-CP 225 in step S308 over the N2 interface to setup PDU session resources for the PDU session to be established.

In this embodiment, the CU-CP 225 selects the CRC-UPF 228 in step S309 via which the PDU session is to be established and prepares configuration data for configuring CU-UP functionality in the CRC-UPF 228, and a request to this effect is sent to the selected CRC-UPF 228 in step S310 over interface El.

The CRC-UPF 228 will thus, in step S311, configure the CU-UP functionality based on the configuration data prepared at the CU-CP 225, including creating CU-UP user plane context information for the CU-UP part of the CRC-UPF 228.

In step S312, the CRC-UPF 228 creates UPF user plane context information for the UPF part of the CRC-UPF 228 (i.e. core network user plane context information), and a reference to the UPF user plane context information (i.e. a reference to the core network user plane context information), and associates the UPF user plane context information with the created CU-UP user plane context information; the UPF and CU-UP parts of the CRC-UPF 228 are thereby associated such that the CU-UP knows to which UPF it should forward data in the uplink, and vice versa in the downlink. Further, an N4 interface address designating the CRC-UPF 228 (i.e. the UPF part of the CRC-UPF 228) is allocated and associated with the reference to the created UPF user plane context information, thereby creating an N4 information set, which is sent to the SMF 222 via the CU-CP 225 and the AMF 221 in steps S313, S315 and S316. As previously described, the CU-CP 225 performs an

AN resources setup procedure with the NG UE 210 in step S314. Information sent to the NG UE 210 in step S314 comprises the NAS message previously received from the AMF 221 in step S308.

Different approaches are possible for the UPF user plane context information created in step S312; it may be the same as the CU-UP user plane context information and in such case thus constitute a common CRC-UPF user plane context information that either is used for both the CU-UP and the UPF part or it maybe used to associate the CU-UP and UPF user plane contexts internally in the CRC-UPF 228. In step S317, the SMF 222 utilizes the N4 interface address in the received N4 information set to identify the CRC-UPF 228 to be configured. The SMF 222 also prepares UPF functionality configuration data for the UPF to be configured. The SMF 222 sends the UPF functionality configuration data and the reference to the created UPF user plane context information to the CRC- UPF 228 - directly via the N4 interface - in step S318.

In step S319, the CRC-UPF 228 configures the previously created UPF user plane context information based on the UPF functionality configuration data prepared by, and received from, the SMF 222. The received reference to the UPF user plane context information is used to identify the correct user plane context in the CRC-UPF (different alternatives are possible as described above in connection to step S312). Hence, with the configuration of the previously created UPF user plane context information, the UPF functionality of the CRC-UPF 228 is enabled.

Thereafter, the CRC-UPF 228 sends a response (to the N4 session

establishment request received in step S318) to the SMF 222 in step S320 over the N4 interface. The UPF transport address and the CRC-UPF TEID possibly included in the response would enable establishment of a N9 interface between the CRC-UPF 228 and a further UPF in a scenario where a plurality of UPFs are utilized.

Finally, in step S321, the PDU session is established with a user plane tunnel between the NG UE 210, the DU 227 and the CRC-UPF 228. It is further envisaged that the NG-RAN may perform an initial selection of the CRC-UPF 228 already at initial attach of the UE 210, or when the UE 219 is transitioning from IDLE to CONNECTED state. The NG-RAN would then indicate the selected CRC-UPF in conjunction with step S301.

In this case the NG-RAN has not yet received any PDU session resource request from the CN and therefore the selection would happen before any resources are setup on the CRC-UPF 228. The advantage of this is that the SMF 222 can start setting up N4 resources in the CRC-UPF 228 selected by NG-RAN already at steps S303-S304, prior to resources being setup in NG- RAN. When the SMF 222 configures the UPF part of the CRC-UPF 228 selected by NG-RAN, the CRC-UPF 228 allocates the El information as will be described in Figure 6 where the El information is transferred from the CRC-UPF 228 to the CU-CP 225. This embodiment could be seen as a hybrid of the

embodiments of Figures 5 and 6 as NG-RAN/CU-CP 225 selects the CRC- UPF 228 but El information is provided from the CRC-UPF 228 to the NG- RAN/CU-CP 225 via the SMF 222 and the AMF 221 to enable the CU-CP 225 to configure the CU-UP part of the CRC-UPF 228.

Figure 6 shows a signalling diagram illustrating establishment of a PDU session for the NG UE 210 in the 5G communication network 200 of Figure 4 according to an embodiment, where the SMF 222 performs the selection of the CRC-UPF 228. Again, the first five steps S401-S405 of the PDU session establishment process are identical to the first five steps S101-S105 as illustrated in Figure 3.

Hence, in a first step S401, the NG UE 210 sends a request for establishment of a PDU session to the AMF 221 which in step S402 selects an SMF 222 via which the PDU session will be managed.

In step S403, the AMF 221 sends the PDU session request to the selected SMF 222, which transmits a response message back to the AMF 221 in step S404 before carrying through a PDU session authentication/ authorization procedure with the NG UE 210 in step S405.

Now, in contrast to the embodiment of Figure 5, in this embodiment, if the SMF 222 successfully authenticates the NG UE 210, the SMF 222 selects the CRC-UPF 228 in step S406 via which the PDU session is to be established and prepares configuration data for configuring UPF functionality in the CRC-UPF 228, and a request to this effect is sent to the selected CRC-UPF 228 in step S407 directly over interface N4.

In step S408, the CRC-UPF 228 will thus configure the UPF functionality based on the configuration data prepared at, and received from, the SMF 222, including creating UPF user plane context information for the UPF part of the CRC-UPF 228.

In step S409, the CRC-UPF 228 creates CU-UP user plane context

information for the CU-UP part of the CRC-UPF 228 (i.e. radio access network user plane context information), and a reference to the CU-UP user plane context information (i.e. a reference to the radio access network user plane context information), and associates the UPF user plane context information with the created CU-UP user plane context information; the UPF and CU-UP parts of the CRC-UPF 228 are thereby associated such that the CU-UP knows to which UPF it should forward data in the uplink, and vice versa in the downlink. Further, an El interface address designating the CRC- UPF 228 (i.e. the CU-UP part of the CRC-UPF 228) is allocated and associated with the reference to the created CU-UP user plane context information, thereby creating an El information set, which is sent to the CU- CP 225 via the SMF 222 and the AMF 221 in steps S410, S411 and S412 along with a message intended for the UE 210 for enabling establishment of a communication session.

Again, different approaches are possible for the CU-UP user plane context information created in step S409; it maybe the same as the UPF user plane context information and in such case thus constitute a common CRC-UPF user plane context information that either is used for both the CU-UP and the UPF part or it maybe used to associate the CU-UP and UPF user plane contexts internally in the CRC-UPF 228.

In step S413, the CU-CP 225 utilizes the El interface address in the received El information set to identify the CU-UP in the CRC-UPF 228 to be configured. The CU-CP 225 also prepares CU-UP functionality configuration data for the CU-UP to be configured.

The CU-CP 225 sends the CU-CP functionality configuration data and the reference to the created CU-UP user plane context information to the CRC- UPF 228 - directly via the El interface - in step S414. In step S415, the CRC-UPF 228 configures the previously created CU-UP user plane context information based on the CU-UP functionality configuration data prepared by, and received from, the CU-CP 225. The received reference to the created CU-UP user plane context information is used to identify the correct user plane context in the CRC-UPF (different alternatives are possible as described above in connection to step S409). Hence, with the

configuration of the previously created CU-UP user plane context

information, the CU-UP functionality of the CRC-UPF 228 is enabled.

Thereafter, the CRC-UPF 228 sends a response (to the El session

establishment request received in step S414) to the CU-CP 225 in step S416 over the El interface.

As previously described, the CU-CP 225 performs an AN resources setup procedure with the NG UE 210 in step S417.

The CU-CP 225 sends a response to the AMF in step S418 that the PDU session is successfully setup, and the AMF 221 in its turn confirms the successful setup to the SMF 222 in step S419.

Finally, in step S420, the PDU session is established with a user plane tunnel between the NG UE 210, the DU 227 and the CRC-UPF 228.

It is also envisaged that the NG-RAN provides recommendation of the CRC- UPF 228 to be selected already at initial attach of the UE 210, or when the UE 210 is transitioning from IDLE to CONNECTED state. The NG-RAN would then indicate the recommended CRC-UPF 228 in conjunction with step S301 of Figure 5.

In this case the NG-RAN has not yet received any PDU session resource request form the CN and therefore the selection of CRC-UPF 228 would happen before any resources are setup on the CRC-UPF 228. The advantage of this is that the SMF 222 can select the CRC-UPF 228 based on knowledge from the RAN. Figure 7 shows a signalling diagram illustrating transmittal of indications from the CU-CP 228 that the CRC-UPF 228 - and thus the functionality provided by the CRC-UPF 228 - indeed is provided in the 5G communication network 200 according to an embodiment. This indication is an important trigger for the SMF 222 to become aware as to whether the CRC-UPF 228 controlled by NG-RAN is supported or not.

In one scenario the indication is sent when a connection is established between the AMF 221 and the CU-CP 225, e.g. indicating that the CRC-UPF functionality is supported for all UEs and all PDU sessions. This can also be enhanced so that the CU-CP 225 indicates for which Data Network Names (DNNs), PDU sessions, network slices (identified e.g. by Network Slice Instance Identifier (NSI ID), or by Network Slice Selection Assistance

Information (NSSAI) and/or Local Area Data Networks (LADNs) the CRC- UPF 228 is supported. The information can be carried for instance in NGAP NG SETUP REQUEST and/or NGAP RAN CONFIGURATION UPDATE messages (as defined in 3GPP TS 38.413) sent from the CU-CP 225 to the AMF 221.

As exemplified in Figure 7, the CU-CP 225 determines in step i) that the CRC- UPF 228 indeed is arranged in the network 200 and which UPF functionality is provided by the CRC-UPF 228 and sends in step ii) an indication thereof to the AMF 221, which stores the received information in step iii) and sends a response to the CU-CP 25 in step iv).

Now, using the reference numerals of previously described Figure 5, the NG UE 210 sends a request for establishment of a PDU session to the AMF 221 in step S301, which AMF in step S302 selects an SMF 222 via which the PDU session will be managed.

In step S303, the AMF 221 sends the PDU session request to the selected SMF 222, which in this embodiment comprises the SMF 222 receiving a message indicating whether the CRC-UPF 228 providing radio access network user plane functionality and core network user plane functionality is arranged in the wireless communication network 200, and which core and radio access network user plane functionality is provided by the CRC-UPF 228.

As is understood, the message indicating whether the CRC-UPF 228 providing radio access network user plane functionality and core network user plane functionality is arranged in the wireless communication network 200, and which core and radio access network user plane functionality is provided by the CRC-UPF 228 could also be a part of the message sent in step S403 of Figure 6. In another scenario the indication is sent as part of UE-related signalling, e.g. when the UE context is created, modified or about to be created in the NG- RAN. In this case, the indication would apply for the UE 210 and all of its PDU sessions. This case can however also be enhanced so that the CU-CP 225 indicates for which UE DNNs/PDU sessions/networks slices/LADNs it supports the CRC-UPF 228. The information can be carried for instance in an

NGAP INITIAL CONTEXT SETUP RESPONSE message (as defined in 3GPP TS 38.413) sent from the CU-CP 225 to the AMF 221 for example during mobility management-related procedures such as registration.

As can be concluded, the signalling from the NG-RAN is to the SMF 222. Following current principles, the AMF 221 would relay the information between the NG-RAN (i.e. the CU-CP 225) and the SMF 222. It is also possible that the NG-RAN would send the indication directly to the SMF 222 if such a direct interface is introduced or standardized in the future. Finally, the SMF 222 uses the indication as to if the CRC-UPF 228 is supported when PDU sessions are created or modified for the UE 210, for example the SMF 222 decides if“normal” UPF(s) or those included in the CRC-UPF 228 is to be used for a PDU session of the UE 210. In still another variant, the NG- RAN indication of CRC-UPF 228 is not signalled to the SMF 222 but instead the SMF 222 is locally configured with this information. A plurality of the above scenarios are based on the CU-CP 225 indicating support for the CRC-UPF 228. A different principle is that the network is configured so that CRC-UPFs 228 are available in specific areas, for example on registration area level. Also in this case different levels are possible i.e. that the CRC-UPFs are supported for all DNNs/PDU sessions/networks slices/LADNs or only for specific DNNs/PDU sessions/networks

slices/LADNs. In this case the configuration of CRC-UPF support can be maintained also in 5GC, e.g. in the AMF 221 and the AMF 221 forwards this information to the SMF 222. The SMF 222 can also maintain the CRC-UPF support on registration area level, assuming that SMF 222 is aware of the current registration area of the UE 210.

Figure 8 shows a signalling diagram illustrating transmittal of indications from the SMF 222 to the CU-CP 225 which CRC-UPF 228 - and thus the functionality provided by the CRC-UPF 228 - indeed can be selected in the 5G communication network 210 according to an embodiment, and possibly which functionality the CRC-UPF 228 provides.

In this embodiment, the SMF 222 provides recommendations about which CRC-UPF 228 the CU-CP 225 should select. The SMF 222 has information on a core network-level, such as UE subscription and policies related

information. In addition, the core network-level information may contain persistent or historical information related to the UE 210, e.g. UE mobility patterns.

This information is useful also in the selection of CRC-UPF 228 as it enables differentiation of network functionality supported for different subscriptions and UE types. In addition, the SMF 222 may recommend a specific CRC-UPF 228 because it is connected to specific local service network or the SMF 222 has knowledge of the optimal path from a CRC-UPF 228 to the next cascaded UPF over the N9 interface. The SMF 222 needs to have some knowledge about the different CRC-UPFs 228 that the CU-CP 225 may select. Otherwise, it would not be possible to provide a recommendation of selection of CRC-UPF.

The knowledge about different CRC-UPFs may differ from situation to situation. For instance, the SMF 222 may have knowledge regarding in which network sites, or types of network sites, the different CRC-UPFs are located and may provide a recommendation accordingly. Hence, the SMF 222 may provide a recommendation identifying one specific network site in which a CRC-UPF should be selected. A network site type maybe defined e.g. as a radio site, hub site, central office site, aggregation site, etc.

In another example, the SMF 222 has knowledge about different CRC-UPF types, for example about the particular UPF functionality supported in the different CRC-UPFs. In this case, the SMF recommendation would then be about a specific CRC-UPF type. In still another example, the SMF 222 has exact knowledge about all CRC- UPFs deployed in the network (and accessible from the current CU-CP). In this case the recommendation would be a specific CRC-UPF to select.

When the CU-CP 225 receives the recommendation(s) from SMF 222, it may take different actions. For instance, the CU-CP 225 may straightforwardly follow the recommendation from the SMF 222 and select a CRC-UPF 225 based on the recommendation (i.e. either based on network site, network site type, CRC-UPF type or a specific CRC-UPF). The CU-CP 225 may also consider local RAN information about the different CRC-UPFs (e.g. load in the different CRC-UPFs, distance between CRC-UPF and the current DU(s) for the UE 210, and any local RAN information related to the UE). In this case, the CU-CP 225 may either follow the SMF recommendation or select another CRC-UPF.

The above description relates to a single SMF recommendation for the CU-CP selection of CRC-UPFs. This may be extended to providing multiple indications of same type, i.e. a list of recommendations. In one example, the list contains two or more different CRC-UPFs that the CU-CP 225 should use in the CRC-UPF selection. In this case, the local RAN information may impact which of the indicated CRC-UPFs is selected by CU-CP 225.

In still another case, the list of recommendations of same type may be prioritized. This means that the SMF 222 provides an indication of the priority or preference in which order the CU-CP 225 should attempt to select CRC-UPFs.

In still another case, the list of recommendations may include indications of different types. This list may also be prioritized, and one example is that highest priority in the list of recommendations may consist of a specific CRC-

UPF while the second highest priority in the list of recommendations may consist of a specific CRC-UPF type.

This can also be used to enable the SMF 222 to send a new recommendation for a CRC-UPF already selected and controlled by the NG-RAN (i.e. by the CU-CP 225). In this case, the recommendation relating to the new CRC-UPF to be selected by the CU-CP 225 is as described above for an initial recommendation of a particular CRC-UPF. Assuming that the CU-CP 225 follows the re-recommendation from the SMF 222, the CU-CP 225 may remain but the selected CRC-UPF changes. Thus, a re-selection of CRC-UPF is performed based on the new recommendation.

Figure 8 shows one example of SMF recommendation for CRC-UPF selection by the CU-CP 225. The first five steps S301-S305 are identical to those described with reference to Figure 5.

However, following the PDU session authentication/authorization of step S305, step S306 will comprise the action of preparing at least one

recommendation to the CU-CP regarding CRC-UPF selection, such as e.g. which particular CRC-UPF 228 should be selected by the CU-CP 225.

This recommendation is sent to the AMF 221 in step S307 over the Nil interface, which sends a request to the CU-CP 225 in step S308 over the N2 interface to setup PDU session resources for the PDU session to be

established, the request comprising the recommendation for CRC-UPF selection, which the CU-CP 225 will consider when selecting the CRC-UPF 228. The CU-CP 225 selects, in line with the recommendation prepared by the SMF 222, the CRC-UPF 228 in step S309 via which the PDU session is to be established and prepares configuration data for configuring CU-UP functionality in the CRC-UPF 228, and a request to this effect is sent to the selected CRC-UPF 228 as described in step S310 with reference to Figure 5. The remaining steps S310-S321 are performed as previously described with reference to Figure 5.

It is further envisaged that the SMF 222 provides recommendations about how the CU-CP 225 shall reselect a CRC-UPF, e.g. at UE mobility.

The recommendation can be based on the SMF 222 being aware in which areas a specific DNN is available, e.g. provided through local breakout functionality to a local service network with remotely deployed applications e.g. in a Edge/Distributed Cloud. One example of this is a PDU session for LADN and the related LADN area that defines where the LADN is available. The LADN area can be defined as a specific part of the network, for example as a list of tracking areas. The SMF recommendation is again on a PDU session level and defines that when the UE 210 is about to leave the LADN area, the CU-CP 225 shall take specific actions for the PDU session restricted to the LADN area. One action is to use the recommendation to not select a new CRC-UPF as long as there is connectivity from the target CU-CP 225 to the CRC-UPF 228. Another action is to trigger release of the PDU Session when the UE 210 leaves the LADN Area. This type of release is typically performed by the SMF 222. The CU-CP 225 may however indicate to the SMF 222 the need to release the PDU session.

A number of mechanisms may be envisaged for controlling CRC-UPF selection by either the CU-CP 225 or the SMF 222. The SMF 222 can either provide a recommendation for CRC-UPF selection or perform the selection of the CRC-UPF. These different embodiments can also be used simultaneously in a network. The basic principles for this are as follows: 1 The CU-CP 225 is configured with information and logic defining if SMF recommendations for CRC-UPF selection, or SMF selection of a CRC-UPF, are allowed. This configuration can be for all PDU sessions or for specific PDU sessions only.

2 The SMF 222 is configured with information and logic defining if SMF recommendations for CRC-UPF selection, or SMF selection of a CRC-UPF, are allowed. Again, this configuration can be for all PDU sessions or for specific PDU sessions only.

3 As an alternative to a local configuration in the SMF 222, the CU-CP 225 may signal to the SMF 222 if SMF recommendations for CRC-UPF selection, and/or SMF selection of a CRC-UPF, are allowed. For instance, with reference to Figure 5, this can be signalled to the SMF 222 in step S303.

4 The signalling from the SMF 222 to the CU-CP 225 is extended with an indication if the included information is an SMF recommendation for CRC- UPF selection, or SMF selection of a CRC-UPF 228. This indication can be added to the SMF recommendation for CRC-UPF selection as shown in steps S307 and S308 of previously described Figure 5.

5 The CU-UP 225 uses the locally configured information and logic, and uses in step S309 of Figure 5 the recommendation prepared by the SMF 222 how to perform CRC-UPF selection. As discussed hereinabove, reselection of a CRC-UPF is envisaged after a communication session has been established with the UE 210. For instance, due to UE mobility, an established PDU session of the UE 210 maybe transferred from one CRC-UPF to another. Other scenarios include a) changing the CU-CP but maintaining the CRC-UPF, b) changing the CRC- UPF but maintaining the CU-CP, and c) changing both the CU-CP and the CRC-UPF.

For instance, a UE may initially be connected to a source CU-CP and move from a source DU to a new, target DU, and further from the source CU-CP to a corresponding new, target CU-CP, while the CRC-UPF is maintained. In addition, the El interface signalling for the UE is moved from being performed with the source CU-CP via the CRC-UPF to being performed with the target CU-CP via the CRC-UPF. However, the direct N4 interface is retained. The transfer of the UE communication from the source CU-CP to the target CU-CP is triggered as Xn handover, i.e. via the direct Xn interface connecting the source CU-CP to the target CU-CP (or via N2/NG-C handover). Thus, normal Xn handover signalling takes place and in addition the source CU-CP provides information about the UE context in the CRC-UPF to the target CU- CP. The UE context information contains El interface address for the CRC- UPF and a pointer or an identifier or a reference to the UE context in the CRC-UPF. This enables the target CU-CP to establish the El interface to the CRC-UPF. After the Xn handover, the target CU-CP performs a so called “path switch” to the current AMF and therefore also the N2/NG-C interface for the UE is moved.

In another scenario, the UE is initially connected to a source CRC-UPF and moves from a source DU to a target DU. The CU-CP is maintained, and the CU-CP selects a new, target CRC-UPF for at least one UE PDU session. In addition, the El interface signalling for the UE is transferred from being performed between the source CRC-UPF and the CU-CP to being performed between the target CRC-UPF and the CU-CP. Thus, communication via the direct N4 interface between the SMF 222 and the source CRC-UPF 228 is moved to the direct N4 interface between the target CRC-UPF and the SMF

222. As part of UE mobility, the CU-CP decides to select the target CRC-UPF for the UE. The CU-CP thus establishes the El interface with the target CRC-UPF and configures at least the CU-UP part of the new, target CRC-UPF.

In addition, as the CRC-UPF is changed, the CU-CP informs the AMF and SMF about the change of CRC-UPF and the new N4 information set

(including the N4 interface address and UPF user plane context information. This allows the SMF to configure the target CRC-UPF via the direct N4 interface, and possibly also trigger signalling towards the UE to add an additional IPv6 prefix, for example for the UE to use as a local breakout address in the target CRC-UPF.

In still an additional variant, the CU-CP maintains a local copy of the current N4 configuration, for the source CRC-UPF and forwards this information to the target CRC-UPF when the El interface to the target CRC-UPF is established. The different variants can also be combined i.e. the local copy of the N4 configuration can be used initially and then CU-CP informs the AMF and SMF about the change of the CRC-UPF as above. This allows the SMF to reconfigure the CRC-UPF as/if needed.

In a scenario where both CU-CP and CRC-UPF changes, the UE IP anchor point address or local breakout address would also change with the CRC-UPF change, which also happens in the case above when CRC-UPF changes and CU-CP is kept.

Figure 9 illustrates a 5G communication network 200 implementing a network node 328 configured to connect a wireless communication device 210 (i.e. the NG UE) to the network 200 according to an embodiment, being a variant of that shown in Figure 4.

In the following, the network node 328 according to the embodiment will be referred to as a Combined Central Unit and User Plane Function (CCU-UPF).

As is shown in Figure 9, the NG-RAN comprises a CCU-UPF 328 according to the embodiment hosting the RRC protocol and the PDCP protocol used for control plane, i.e. the functionality of the CU-CP shown in Figure 4. Further, the UPF functionality and CU-UP functionality is integrated within the CCU- UPF 328. Hence, the CCU-UPF 328 further hosts the SDAP protocol and the PDCP protocol used for user plane. The CCU-UPF 328 connects to an AMF 221 via the N2 interface, and to a DU 227 via an Fi-C interface, which DU 227 is responsible for connecting the NG UE 210 to the control plane via interface Fi-C and to the user plane via interface Fi-U.

The CCU-UPF 328 connects to a local service network 223 and a data network 213 via the N6 interface, and to a UPF 212 via the N9 interface (or to only one of the network 213 and the UPF 212). Any combination of these scenarios is possible.

Further, the CCU-UPF 328 is arranged with a direct N4 interface to the SMF 222 via which the SMF 222 is controlling the UPF functionality of the CCU- UPF 328. The Nil interface can alternatively be realized using service-based interfaces utilized by the AMF 221 and SMF 222, i.e. Namf and Nsmf, respectively.

Advantageously, with the CCU-UPF 328 user plane latency, control plane latency, as well as number of signalling interfaces in the network is reduced. Further, the CCU-UPF 328 advantageously also enables removal of the user plane tunnel between 5GC and NG-RAN as the N3 interface becomes an internal interface in the CCU-UPF 328, and so will the El interface.

Figure 10 illustrates a CRC-UPF 228 according to an embodiment. The steps of the method performed by the CRC-UPF 228 of enabling establishment of user plane connectivity for a wireless communication device with a wireless communication network according to embodiments are in practice performed by a processing unit 415 embodied in the form of one or more microprocessors arranged to execute a computer program 416 downloaded to a suitable storage volatile medium 417 associated with the microprocessor, such as a Random Access Memory (RAM), or a non-volatile storage medium such as a Flash memory or a hard disk drive. The processing unit 415 is arranged to cause the CRC-UPF 228 to carry out the method according to embodiments when the appropriate computer program 416 comprising computer-executable instructions is downloaded to the storage medium 417 and executed by the processing unit 415. The storage medium 417 may also be a computer program product comprising the computer program 416. Alternatively, the computer program 416 may be transferred to the storage medium 417 by means of a suitable computer program product, such as a Digital Versatile Disc (DVD) or a memory stick. As a further alternative, the computer program 416 may be downloaded to the storage medium 417 over a network. The processing unit 415 may alternatively be embodied in the form of a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), etc. Figure 11 illustrates a core network control plane function 222 configured to provide session management according to an embodiment in the form of an SMF. The steps of the method performed by the SMF 222 of enabling establishment of user plane connectivity for a wireless communication device with a wireless communication network according to embodiments are in practice performed by a processing unit 425 embodied in the form of one or more microprocessors arranged to execute a computer program 426 downloaded to a suitable storage volatile medium 427 associated with the microprocessor, such as a Random Access Memory (RAM), or a non-volatile storage medium such as a Flash memory or a hard disk drive. The processing unit 425 is arranged to cause the SMF 222 to carry out the method according to embodiments when the appropriate computer program 426 comprising computer-executable instructions is downloaded to the storage medium 427 and executed by the processing unit 425. The storage medium 427 may also be a computer program product comprising the computer program 426. Alternatively, the computer program 426 maybe transferred to the storage medium 427 by means of a suitable computer program product, such as a Digital Versatile Disc (DVD) or a memory stick. As a further alternative, the computer program 426 maybe downloaded to the storage medium 427 over a network. The processing unit 425 may alternatively be embodied in the form of a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a complex

programmable logic device (CPLD), etc.

Figure 12 illustrates a radio access network control plane function 225 according to an embodiment in the form of a CU-CP. The steps of the method performed by the CU-CP 225 of enabling establishment of user plane connectivity for a wireless communication device with a wireless

communication network according to embodiments are in practice

performed by a processing unit 435 embodied in the form of one or more microprocessors arranged to execute a computer program 436 downloaded to a suitable storage volatile medium 437 associated with the microprocessor, such as a Random Access Memory (RAM), or a non-volatile storage medium such as a Flash memory or a hard disk drive. The processing unit 435 is arranged to cause the CU-CP 225 to carry out the method according to embodiments when the appropriate computer program 436 comprising computer-executable instructions is downloaded to the storage medium 437 and executed by the processing unit 435. The storage medium 437 may also be a computer program product comprising the computer program 436. Alternatively, the computer program 436 maybe transferred to the storage medium 427 by means of a suitable computer program product, such as a Digital Versatile Disc (DVD) or a memory stick. As a further alternative, the computer program 436 maybe downloaded to the storage medium 437 over a network. The processing unit 435 may alternatively be embodied in the form of a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), etc.

The disclosure has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the disclsoure, as defined by the appended patent claims.

Claims

1. A network node (228) configured to connect a wireless communication device (210) to a user plane in a wireless communication network (200) in which the network node (228) is arranged, the network node (228) comprising a processing unit (415) and a memory (417), said memory containing instructions (416) executable by said processing unit, whereby the network node (228) is operative to:

provide core network user plane functionality; and

provide radio access network user plane functionality; the network node (228) further being arranged with:

a first direct interface to a core network control plane function (222) configured to provide session management via which the core network user plane functionality is configured and a second direct interface to a radio access network control plane function (225) via which the radio access network user plane functionality is configured.

2. The network node (228) of claim 1, wherein the provided radio access network user plane functionality is Central Unit User Plane, CU-UP, functionality, and the provided core network user plane functionality is User Plane Function, UPF, functionality.

3. A method performed by the network node (228) of any one of the preceding claims for enabling establishment of user plane connectivity for a wireless communication device (210) with a wireless communication network (200), the method comprising:

receiving (S310), from the radio access network control plane function (225) via the second direct interface, configuration data arranged to configure the provided radio access network user plane functionality, the configuration data having been prepared at the radio access network control plane function (225);

configuring (S311) the radio access network user plane functionality based on the received configuration data prepared at the radio access network control plane function (225); allocating (S312) an address for the network node (228) and creating a core network user plane context information and a reference to the created core network user plane context information, the address being configured to designate the network node (228) via the first interface;

transmitting (S313) the reference to the created core network user plane context information and information identifying the allocated address, to the radio access network control plane function (225) via the second direct interface, for further transfer to the core network control plane function (222) configured to provide session management;

receiving (S318), from the core network control plane function (222) configured to provide session management via the first direct interface, configuration data arranged to configure the provided core network user plane functionality and the reference to the created core network user plane context information;

configuring (S319) the created core network user plane context information based on the received configuration data prepared at the core network control plane function (222) configured to provide session

management, the created core network user plane context information being identified by the received reference to the created core network user plane context information, wherein the providing of the core network user plane functionality of the network node (228) is enabled; and

establishing (S321) the user plane connectivity with the wireless communication device (210).

4. A method performed by the network node (228) of any one of claims 1 or 2 for enabling establishment of user plane connectivity for a wireless communication device (210) with a wireless communication network (200), the method comprising:

receiving (S407), from the core network control plane function (222) configured to provide session management (222) via the first direct interface, configuration data arranged to configure the provided core network user plane functionality, the configuration data having been prepared at the core network control plane function (222); configuring (S408) the core network user plane functionality based on the received configuration data prepared at the core network control plane function (222);

allocating (S409) an address for the network node (228) and creating a radio access network user plane context information and a reference to the created radio access network user plane context information, the address being configured to designate the network node (228) via the second interface;

transmitting (S410) the reference to the created radio access network user plane context information and information identifying the allocated address, to the core network control plane function (222) configured to provide session management (222) via the first direct interface, for further transfer to the radio access network control plane function (225);

receiving (S414), from the radio access network control plane function (225) via the second direct interface, configuration data arranged to configure the provided radio access network user plane functionality and the reference to the created radio access network user plane context information;

configuring (S415) the created radio access network user plane information based on the received configuration data prepared at the radio access network control plane function (225), the created radio access network user plane functionality being identified by the received reference to the created radio access network user plane context information, wherein the providing of the radio access network user plane functionality of the network node (228) is enabled; and

establishing (S420) the user plane connectivity with the wireless communication device (210).

5. A method performed by a core network control plane function (222) configured to provide session management for enabling establishment of user plane connectivity for a wireless communication device (210) with a wireless communication network (200), the method comprising:

receiving (S403), from a core network control plane function (221) configured to provide mobility management, a request to establish user plane connectivity for a wireless communication device (210);

selecting (S406) a network node (228) providing core network user plane functionality and radio access network user plane functionality;

preparing (S406) configuration data arranged to configure core network user plane functionality of the selected network node (228) providing said core network user plane functionality and radio access network user plane functionality; and

transmitting (S407), to the network node (228) via a direct interface, the configuration data to the network node (228).

6. The method of claim 5, further comprising:

receiving (S410), from the network node (228) providing core network user plane functionality and radio access network user plane functionality via the direct interface a reference to a radio access network user plane context information having been prepared by the network node (228) providing said core network user plane functionality and radio access network user plane functionality, and information identifying an allocated address to the network node (228); and

transmitting (S411) the reference to a radio access network user plane context information prepared at the network node (228) and the information identifying the allocated address towards a radio access network control plane function (225).

7. A method performed by a core network control plane function (222) configured to provide session management for enabling establishment of user plane connectivity for a wireless communication device (210) with a wireless communication network (200), the method comprising:

receiving (S316), from a core network control plane function (221) configured to provide mobility management, a reference to a core network user plane context information prepared at a network node (228) providing core network user plane functionality and radio access network user plane functionality and information identifying an allocated address to the network node (228);

preparing (S317) configuration data arranged to configure core network user plane functionality of the network node (228) identified by the received address information; and

transmitting (S318), to the network node (228) via a direct interface, the prepared configuration data arranged to configure the core network user plane functionality of the network node and the reference to a core network user plane context information (228).

8. The method of any one of claims 5-7, wherein the receiving (S303,

S403), from the core network control plane function (221) configured to provide mobility management, of a request to establish a communication session for a wireless communication device (210), further comprises:

receiving a message indicating whether the network node (228) providing core network user plane functionality and radio access network user plane functionality is arranged in the wireless communication network (200) or not, and which core network user plane functionality is provided by the network node (228).

9. The method of any one of claims 7-8, further comprising:

creating (8306a) a recommendation to the radio access network control plane function (225) regarding selection of the network node (228) providing said core network user plane functionality and radio network user plane functionality; and

sending (S307) the created recommendation towards the radio access network control plane function (225).

10. A method performed by a radio access network control plane function (225), for enabling establishment of user plane connectivity for a wireless communication device (210) with a wireless communication network (200), the method comprising:

receiving (S308), from a core network control plane function (221) configured to provide session management, a request to establish user plane connectivity for a wireless communication device (210);

selecting (S309) a network node (228) providing core network user plane functionality and radio access network user plane functionality; preparing (S309) configuration data arranged to configure radio access network user plane functionality of the selected network node (228) providing core network user plane functionality and said radio access network user plane functionality; and

transmitting (S310), to the selected network node (228) providing core network user plane functionality and radio access network user plane functionality via a direct interface, the prepared configuration data.

11. The method of claim 10, further comprising:

receiving (S313), from the selected network node (228) providing core network user plane functionality and radio access network user plane functionality via the direct interface, a reference to a core network user plane context information and information identifying an allocated address to the selected network node (228); and

transmitting (S315) the reference to a core network user plane context information and the information identifying an allocated address to the selected network node (228) towards the core network control plane function (222) configured to provide session management.

12. The method of any one of claims 10-11, wherein the receiving (S308), from a core network control plane function (221) configured to provide session management, a request to establish user plane connectivity for a wireless communication device (210) further comprises;

receiving a recommendation created at the core network control plane function (222) configured to provide session management (222) regarding selection of the network node (228) providing said core network user plane functionality and radio network user plane functionality; wherein the selecting (S309) of the network node (228) providing core network user plane functionality and radio access network user plane functionality further comprises:

selecting (S309) the network node (228) providing core network user plane functionality and radio access network user plane functionality based on the received recommendation.

13. A method performed by a radio access network control plane function (225) for enabling establishment of user plane connectivity for a wireless communication device (210) with a wireless communication network (200), the method comprising:

receiving (S412), from a core network control plane function (221) configured to provide session management, a request to establish user plane connectivity for a wireless communication device (210), the request comprising a reference to a radio access network user plane context information prepared at a network node (228) providing radio access network user plane functionality and core network user plane functionality, and information identifying an allocated address to the network node (228); preparing (S413) configuration data arranged to configure radio access network user plane functionality of the network node (228) identified by the received address information ; and

transmitting (S414) the prepared configuration data arranged to configure the radio access network user plane functionality and the reference to a radio access network user plane context information to the network node (228) via a direct interface.

14. A computer program (416) comprising computer-executable

instructions for causing a network node (228) to perform steps recited in any one of claims 3-4 when the computer-executable instructions are executed on a processing unit (415) included in the network node (228).

15. A computer program product comprising a computer readable medium (417), the computer readable medium having the computer program (416) according to claim 14 embodied thereon.

16. A computer program (426) comprising computer-executable

instructions for causing a core network control plane function (222) configured to provide session management to perform steps recited in any one of claims 5-9 when the computer-executable instructions are executed on a processing unit (425) included in the core network control plane function (222) configured to provide session management.

17. A computer program product comprising a computer readable medium (427), the computer readable medium having the computer program (426) according to claim 16 embodied thereon.

18. A computer program (436) comprising computer-executable

instructions for causing a radio access network control plane function (225) to perform steps recited in any one of claims 10-13 when the computer- executable instructions are executed on a processing unit (435) included in the radio access network control plane function (225).

19. A computer program product comprising a computer readable medium (437), the computer readable medium having the computer program (436) according to claim 18 embodied thereon.

20. A core network control plane function (222) configured to provide session management for enabling establishment of user plane connectivity for a wireless communication device (210) with a wireless communication network (200), the core network control plane function (222) configured to provide session management comprising a processing unit (425) and a memory (427), said memory containing instructions (426) executable by said processing unit, whereby the core network control plane function (222) configured to provide session management is operative to:

receive, from a core network control plane function (221) configured to provide mobility management, a request to establish user plane connectivity for a wireless communication device (210);

select a network node (228) providing core network user plane functionality and radio access network user plane functionality;

prepare configuration data arranged to configure core network user plane functionality of the selected network node (228) providing said core network user plane functionality and radio access network user plane functionality; and

transmit, to the network node (228) via a direct interface, the configuration data to the network node (228).

21. The core network control plane function (222) configured to provide session management of claim 20, further being operative to:

receive, from the network node (228) providing core network user plane functionality and radio access network user plane functionality via the direct interface a reference to a radio access network user plane context information having been prepared by the network node (228) providing said core network user plane functionality and radio access network user plane functionality, and information identifying an allocated address to the network node (228); and

transmit the reference to a radio access network user plane context information prepared at the network node (228) and the information identifying the allocated address towards a radio access network control plane function (225).

22. A core network control plane function (222) configured to provide session management for enabling establishment of user plane connectivity for a wireless communication device (210) with a wireless communication network (200), the core network control plane function (222) configured to provide session management comprising a processing unit (425) and a memory (427), said memory containing instructions (426) executable by said processing unit, whereby the core network control plane function (222) configured to provide session management is operative to:

receive, from a core network control plane function (221) configured to provide mobility management, a reference to a core network user plane context information prepared at a network node (228) providing core network user plane functionality and radio access network user plane functionality and information identifying an allocated address to the network node (228);

prepare configuration data arranged to configure core network user plane functionality of the network node (228) identified by the received address information; and

transmit, to the network node (228) via a direct interface, the prepared configuration data arranged to configure the core network user plane functionality of the network node and the reference to a core network user plane context information (228).

23. The core network control plane function (222) configured to provide session management of any one of claims 20-22, further being operative to: receive a message indicating whether the network node (228) providing core network user plane functionality and radio access network user plane functionality is arranged in the wireless communication network (200) or not, and which core network user plane functionality is provided by the network node (228).

24. The core network control plane function (222) configured to provide session management of any one of claims 22-23, further being operative to: create a recommendation to the radio access network control plane function (225) regarding selection of the network node (228) providing said core network user plane functionality and radio network user plane functionality; and

send the created recommendation towards the radio access network control plane function (225).

25. A radio access network control plane function (225) for enabling establishment of user plane connectivity for a wireless communication device (210) with a wireless communication network (200), the radio access control network control plane function (225) comprising a processing unit (435) and a memory (437), said memory containing instructions (436) executable by said processing unit, whereby the radio access control network control plane function (225) is operative to:

receive, from a core network control plane function (221) configured to provide session management, a request to establish user plane connectivity for a wireless communication device (210);

prepare configuration data arranged to configure radio access network user plane functionality of the selected network node (228) providing core network user plane functionality and said radio access network user plane functionality; and

transmit, to the selected network node (228) providing core network user plane functionality and radio access network user plane functionality via a direct interface, the prepared configuration data.

26. The radio access network control plane function (225) of claim 25, further being operative to:

receive, from the selected network node (228) providing core network user plane functionality and radio access network user plane functionality via the direct interface, a reference to a core network user plane context information and information identifying an allocated address to the selected network node (228); and

transmit the reference to a core network user plane context information and the information identifying an allocated address to the selected network node (228) towards the core network control plane function (222) configured to provide session management.

27. The radio access network control plane function (225) of claim 29, further being operative to, when receiving, from a core network control plane function (221) configured to provide session management, a request to establish user plane connectivity for a wireless communication device (210): receive a recommendation created at the core network control plane function (222) configured to provide session management (222) regarding selection of the network node (228) providing said core network user plane functionality and radio network user plane functionality; and when selecting the network node (228) providing core network user plane functionality and radio access network user plane functionality:

select the network node (228) providing core network user plane functionality and radio access network user plane functionality based on the received recommendation.

28. A radio access control network control plane function (225) for enabling establishment of user plane connectivity for a wireless communication device (210) with a wireless communication network (200), the radio access control network control plane function (225) comprising a processing unit (435) and a memory (437), said memory containing instructions (436) executable by said processing unit, whereby the radio access control network control plane function (225) is operative to:

receive, from a core network control plane function (221) configured to provide session management, a request to establish user plane connectivity for a wireless communication device (210), the request comprising a reference to a radio access network user plane context information prepared at a network node (228) providing radio access network user plane functionality and core network user plane functionality, and information identifying an allocated address to the network node (228);

prepare configuration data arranged to configure radio access network user plane functionality of the network node (228) identified by the received address information ; and

transmit the prepared configuration data arranged to configure the radio access network user plane functionality and the reference to a radio access network user plane context information to the network node (228) via a direct interface.