WO2025153757A1

WO2025153757A1 - Apparatus, method and computer program for direct exposure

Info

Publication number: WO2025153757A1
Application number: PCT/FI2024/050617
Authority: WO
Inventors: Samer Bazzi; Ece GOSHI; Mohammad Soliman; Hannu Flinck
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2024-01-17
Filing date: 2024-11-15
Publication date: 2025-07-24
Anticipated expiration: 2026-07-17
Also published as: GB2637323A; GB202400643D0

Abstract

There is provided an apparatus comprising means for determining, at a distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the core network function, means for discovering the at least one core network function, means for receiving at least one control plane message of the at least one type of control plane messages from one of a user equipment, UE, and the at least one core network function at the distributed unit via a direct transport link between the distributed unit and the core network function and means for providing the received at least one control plane message from the distributed unit to the other of the user equipment and the at least one core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

Description

Title

APPARATUS, METHOD AND COMPUTER PROGRAM FOR DIRECT EXPOSURE

Technical Field

Various example embodiments of this disclosure relate to a method, apparatus, system and computer program, and in particular (but not exclusively) to direct exposure of gNB distributed unit to core network functions.

Background

A communication system can be seen as a facility that enables communication sessions between two or more entities, such as user terminals, base stations and/or other nodes by providing carriers between the various entities involved in the communications path. A communication system can be provided, for example, by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications, such as voice, video, electronic mail (email), text message, multimedia and/or content data and so on. Nonlimiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.

In a wireless communication system, at least a part of a communication session between at least two stations occurs over a wireless link. Examples of wireless systems comprise public land mobile networks (PLMN), satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN). Some wireless systems can be divided into cells, and are therefore often referred to as cellular systems.

A user can access the communication system by means of an appropriate communication device or terminal. A communication device of a user may be referred to as user equipment (UE) or user device. A communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other users. The communication device may access a carrier provided by a station, for example a base station of a cell, and transmit and/or receive communications on the carrier. The communication system and associated devices may operate in accordance with a given standard or specification, which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and/or parameters which shall be used for the connection are also typically defined. One example of a communications system is Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN) (3G radio). Other examples of communication systems are the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology and so-called 5G or New Radio (NR) networks. NR is being standardized by the 3rd Generation Partnership Project (3GPP). Other examples of communication systems include 5G-Advanced (NR Rel-18 and beyond) and 6G.

Some example embodiments of this disclosure will be described with respect to certain aspects. These aspects are not intended to indicate key or essential features of the various example embodiments of this disclosure, nor are they intended to be used to limit the scope of thereof. Other features, aspects, and elements will be readily apparent to a person skilled in the art in view of this disclosure. For example, it should be appreciated that further aspects may be provided by the combination of any two or more of the various aspects described below.

In a first aspect, there is provided an apparatus comprising means for determining, at a distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the core network function, means for discovering the at least one core network function, means for receiving at least one control plane message of the at least one type of control plane messages from one of a user equipment, UE, and the at least one core network function at the distributed unit via a direct transport link between the distributed unit and the core network function and means for providing the received at least one control plane message from the distributed unit to the other of the user equipment and the at least one core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

The direct transport link may comprise a point-to-point application layer protocol or a service based interface. The at least one type of control plane messages may comprise UE registration messages and the apparatus may comprise means for providing a UE registration request message from the distributed unit to the at least one core network function via the direct transport link between the distributed unit and the core network function and means for receiving a UE registration accept message at the distributed unit from the at least one core network function via the direct transport link between the distributed unit and the core network function.

The apparatus may comprise means for receiving a UE identity request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and means for providing a UE identity response message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The apparatus may comprise means for receiving a UE authentication request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and means for providing a UE authentication response message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The at least one type of control plane messages may comprise UE deregistration messages and the apparatus may comprise means for providing a UE deregistration request message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function and means for receiving a UE deregistration accept message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function or means for receiving the UE deregistration request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and means for providing the UE deregistration accept message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The at least one core network function may comprise an access and mobility and management function.

The at least one type of control plane messages may comprise positioning messages and the apparatus may comprise means for receiving a UE positioning capability request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, means for providing a UE positioning capability response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, means for receiving a positioning information request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, means for providing a positioning information response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, means for receiving a positioning activation request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, means for providing a positioning activation response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, means for receiving a positioning measurement request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and means for providing a positioning measurement response to the at least one core network function from the distributed unit to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The at least one core network function may be an access and mobility management function or a location management function.

Means for discovering the at least one core network function may comprise means for obtaining core network function topology information at the distributed unit.

The core network function topology information may comprise at least one of an identifier associated with the at least one core network function or an address associated with the at least one core network function.

The core network function topology information may be configured at the distributed unit or the apparatus may comprise means for receiving the core network function topology information from at least one core network function or a centralised unit of the access node.

Means for determining, at the distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the at least one core network function may comprise means for providing control plane capabilities to a centralised unit of the access node from the distributed unit in an F1 setup request message and means for receiving, from the centralised unit at the distributed unit, an indication of accepted capabilities in an F1 setup response.

Means for determining, at the distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the at least one core network function may comprise means for providing control plane capabilities associated with the user equipment or a slice of the user equipment to a centralised unit of the access node from the distributed unit in a LIE registration message and means for receiving from the centralised unit at the distributed unit an indication of accepted capabilities associated with the user equipment or a slice of the user equipment in a LIE registration response message.

In a second aspect, there is provided an apparatus comprising means for discovering, at a core network function, at least one distributed unit of at least one access node and means for receiving from, or providing to, the at least one distributed unit at least one control plane message of at least one type of control plane messages at the core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

The apparatus may comprise means for receiving the at least one control plane message from the distributed unit at the at least one core network function via a point-to-point application layer protocol or a service based interface.

Means for discovering the at least one core distributed unit may comprise means for obtaining distributed unit topology information at the core network function.

The distributed unit topology information may comprise at least one of an identifier associated with the at least one distributed unit or an address associated with the at least one distributed unit. The distributed unit topology information may be configured at the core network function or the apparatus may comprise means for receiving the distributed unit topology information from at least one distributed unit or a centralised unit of the access node.

In a third aspect, there is provided a method comprising determining, at a distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the core network function, discovering the at least one core network function, receiving at least one control plane message of the at least one type of control plane messages from one of a user equipment, LIE, and the at least one core network function at the distributed unit via a direct transport link between the distributed unit and the core network function and providing the received at least one control plane message from the distributed unit to the other of the user equipment and the at least one core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

The direct transport link may comprise a point-to-point application layer protocol or a service based interface.

The at least one type of control plane messages may comprise LIE registration messages and the method may comprise providing a LIE registration request message from the distributed unit to the at least one core network function via the direct transport link between the distributed unit and the core network function and receiving a LIE registration accept message at the distributed unit from the at least one core network function via the direct transport link between the distributed unit and the core network function.

The method may comprise receiving a LIE identity request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and providing a LIE identity response message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The method may comprise receiving a LIE authentication request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and providing a LIE authentication response message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The at least one type of control plane messages may comprise UE deregistration messages and the method may comprise providing a UE deregistration request message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function and receiving a UE deregistration accept message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function or receiving the UE deregistration request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and providing the UE deregistration accept message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The at least one type of control plane messages may comprise positioning messages and the method may comprise receiving a UE positioning capability request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, providing a UE positioning capability response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, receiving a positioning information request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, providing a positioning information response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, receiving a positioning activation request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, providing a positioning activation response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, receiving a positioning measurement request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and mea providing a positioning measurement response to the at least one core network function from the distributed unit to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

Discovering the at least one core network function may comprise obtaining core network function topology information at the distributed unit.

The core network function topology information may be configured at the distributed unit or the method may comprise receiving the core network function topology information from at least one core network function or a centralised unit of the access node.

Determining, at the distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the at least one core network function may comprise providing control plane capabilities to a centralised unit of the access node from the distributed unit in an F1 setup request message and receiving, from the centralised unit at the distributed unit, an indication of accepted capabilities in an F1 setup response.

Determining, at the distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the at least one core network function may comprise providing control plane capabilities associated with the user equipment or a slice of the user equipment to a centralised unit of the access node from the distributed unit in a UE registration message and receiving from the centralised unit at the distributed unit an indication of accepted capabilities associated with the user equipment or a slice of the user equipment in a UE registration response message.

In a fourth aspect, there is provided a method comprising discovering, at a core network function, at least one distributed unit of at least one access node and receiving from, or providing to, the at least one distributed unit at least one control plane message of at least one type of control plane messages at the core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

The method may comprise receiving the at least one control plane message from the distributed unit at the at least one core network function via a point-to-point application layer protocol or a service based interface.

Discovering the at least one core distributed unit may comprise obtaining distributed unit topology information at the core network function.

The distributed unit topology information may comprise at least one of an identifier associated with the at least one distributed unit or an address associated with the at least one distributed unit.

The distributed unit topology information may be configured at the core network function or the method may comprise receiving the distributed unit topology information from at least one distributed unit or a centralised unit of the access node.

In a fifth aspect, there is provided an apparatus comprising at least one processor, and at least one memory storing instructions which, when executed by the processor, cause the apparatus at least to determine, at a distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the core network function, discover the at least one core network function, receive at least one control plane message of the at least one type of control plane messages from one of a user equipment, LIE, and the at least one core network function at the distributed unit via a direct transport link between the distributed unit and the core network function and provide the received at least one control plane message from the distributed unit to the other of the user equipment and the at least one core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages. The direct transport link may comprise a point-to-point application layer protocol or a service based interface.

The at least one type of control plane messages may comprises UE registration messages and the apparatus may be caused to provide a UE registration request message from the distributed unit to the at least one core network function via the direct transport link between the distributed unit and the core network function and receive a UE registration accept message at the distributed unit from the at least one core network function via the direct transport link between the distributed unit and the core network function.

The apparatus may be caused to receive a UE identity request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and provide a UE identity response message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The apparatus may be caused to receive a UE authentication request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and provide a UE authentication response message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The at least one type of control plane messages may comprise UE deregistration messages and the apparatus may be caused to provide a UE deregistration request message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function and receive a UE deregistration accept message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function or receive the UE deregistration request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and provide the UE deregistration accept message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The at least one core network function may comprise an access and mobility and management function. The at least one type of control plane messages may comprise positioning messages and the apparatus may be caused to receive a UE positioning capability request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, provide a UE positioning capability response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, receive a positioning information request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, provide a positioning information response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, receive a positioning activation request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, provide a positioning activation response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, receive a positioning measurement request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and provide a positioning measurement response to the at least one core network function from the distributed unit to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The apparatus may be caused to obtain core network function topology information at the distributed unit.

The core network function topology information may be configured at the distributed unit or the apparatus may be caused to receive the core network function topology information from at least one core network function or a centralised unit of the access node.

The apparatus may be caused to provide control plane capabilities to a centralised unit of the access node from the distributed unit in an F1 setup request message and receive, from the centralised unit at the distributed unit, an indication of accepted capabilities in an F1 setup response.

The apparatus may be caused to provide control plane capabilities associated with the user equipment or a slice of the user equipment to a centralised unit of the access node from the distributed unit in a LIE registration message and receive from the centralised unit at the distributed unit an indication of accepted capabilities associated with the user equipment or a slice of the user equipment in a LIE registration response message.

In a sixth aspect, there is provided at least one processor, and at least one memory storing instructions which, when executed by the processor, cause the apparatus at least to discover, at a core network function, at least one distributed unit of at least one access node and receive from, or provide to, the at least one distributed unit at least one control plane message of at least one type of control plane messages at the core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

The apparatus may be caused to receive the at least one control plane message from the distributed unit at the at least one core network function via a point-to-point application layer protocol or a service based interface.

The apparatus may be caused to obtain distributed unit topology information at the core network function.

The distributed unit topology information may be configured at the core network function or the apparatus may be caused to receive the distributed unit topology information from at least one distributed unit or a centralised unit of the access node. In a seventh aspect, there is provided a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: determining, at a distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the core network function, discovering the at least one core network function, receiving at least one control plane message of the at least one type of control plane messages from one of a user equipment, LIE, and the at least one core network function at the distributed unit via a direct transport link between the distributed unit and the core network function and providing the received at least one control plane message from the distributed unit to the other of the user equipment and the at least one core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

The at least one type of control plane messages may comprise LIE registration messages and the apparatus may be caused to perform providing a LIE registration request message from the distributed unit to the at least one core network function via the direct transport link between the distributed unit and the core network function and receiving a LIE registration accept message at the distributed unit from the at least one core network function via the direct transport link between the distributed unit and the core network function.

The apparatus may be caused to perform receiving a LIE identity request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and providing a LIE identity response message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The apparatus may be caused to perform receiving a LIE authentication request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and providing a LIE authentication response message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function. The at least one type of control plane messages may comprise UE deregistration messages and the apparatus may be caused to perform providing a UE deregistration request message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function and receiving a UE deregistration accept message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function or receiving the UE deregistration request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and providing the UE deregistration accept message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The at least one type of control plane messages may comprise positioning messages and the apparatus may be caused to perform receiving a UE positioning capability request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, providing a UE positioning capability response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, receiving a positioning information request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, providing a positioning information response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, receiving a positioning activation request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, providing a positioning activation response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, receiving a positioning measurement request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and providing a positioning measurement response to the at least one core network function from the distributed unit to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function. The at least one core network function may be an access and mobility management function or a location management function.

The core network function topology information may be configured at the distributed unit or the apparatus may be caused to perform receiving the core network function topology information from at least one core network function or a centralised unit of the access node.

In an eighth aspect, there is provided a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: discovering, at a core network function, at least one distributed unit of at least one access node and receiving from, or providing to, the at least one distributed unit at least one control plane message of at least one type of control plane messages at the core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

The apparatus may be caused to perform receiving the at least one control plane message from the distributed unit at the at least one core network function via a point-to-point application layer protocol or a service based interface.

The distributed unit topology information may be configured at the core network function or the apparatus may be caused to perform receiving the distributed unit topology information from at least one distributed unit or a centralised unit of the access node.

In a ninth aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to the third or fourth aspect.

Description of Figures

Some example embodiments will now be described, by way of example only, with reference to the accompanying Figures in which:

Figure 1 shows a schematic diagram of an example 5GS communication system;

Figure 2 shows a schematic diagram of an example mobile communication device;

Figure 3 shows a schematic diagram of an example control apparatus;

Figure 4 shows a flowchart of a method according to an example embodiment;

Figure 5 shows a flowchart of a method according to an example embodiment;

Figure 6 shows a signalling flow according to an example embodiment;

Figure 7 shows a signalling flow according to an example embodiment; Figure 8 shows a signalling flow according to an example embodiment;

Figure 9 shows a signalling flow according to an example embodiment;

Figure 10 shows a signalling flow according to an example embodiment; Figure 11 shows a signalling flow according to an example embodiment;

Detailed Description

Before explaining in detail the various example embodiments, certain general aspects of a wireless communication system and mobile communication devices are briefly explained with reference to Figure 1 , Figure 2 and Figure 3 to assist in understanding the technology underlying the described example embodiments.

An example of a communications system is the 5G or NR concept. Network architecture in NR may be similar to that of LTE-advanced. Base stations of NR systems may be known as next generation NodeBs (gNBs). Changes to the network architecture may depend on the need to support various radio technologies and finer Quality of Service (QoS) support, and some on- demand requirements for, e.g., QoS levels to support Quality of Experience (QoE) for a user. Also network aware services and applications, and service and application aware networks may bring changes to the architecture. Those are related to Information Centric Network (ICN) and User-Centric Content Delivery Network (UC-CDN) approaches. NR may use Multiple Input - Multiple Output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates.

Future networks may utilise network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into “building blocks” or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In radio communications this may mean node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be non-existent. Figure 1 shows a schematic representation of a 5G system (5GS) 100. The 5GS may comprise a user equipment (UE) 102 (which may also be referred to as a communication device or a terminal), a 5G radio access network (5GRAN) 104, a 5G core network (5GCN) 106, one or more internal or external application functions (AF) 108 and one or more data networks (DN) 110.

An example 5G core network (GN) comprises functional entities. The 5GCN 106 may comprise one or more Access and mobility Management Functions (AMF) 112, one or more session management functions (SMF) 114, an authentication server function (ALISF) 116, a Unified Data Management (UDM) 118, one or more user plane functions (UPF) 120, a Unified Data Repository (UDR) 122 and/or a Network Exposure Function (NEF) 124. The UPF is controlled by the SMF (Session Management Function) that receives policies from a PCF (Policy Control Function).

The CN is connected to a UE via the Radio Access Network (RAN). The 5GRAN may comprise one or more gNodeB (gNB) Distributed Unit (DU) functions connected to one or more gNodeB (gNB) Centralized Unit (CU) functions. The RAN may comprise one or more access nodes.

A User Plane Function (UPF) referred to as PDU Session Anchor (PSA) may be responsible for forwarding frames back and forth between the DN and the tunnels established over the 5G towards the UE(s) exchanging traffic with the DN.

A possible mobile communication device will now be described in more detail with reference to Figure 2 showing a schematic, partially sectioned view of a communication device 200. Such a communication device is often referred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a mobile station (MS) or mobile device such as a mobile phone or what is known as a ’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), personal data assistant (PDA) or a tablet provided with wireless communication capabilities, voice over IP (VoIP) phones, portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehiclemounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart devices, wireless customerpremises equipment (CPE), or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services comprise two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided broadcast or multicast data. Non-limiting examples of the content comprise downloads, television and radio programs, videos, advertisements, various alerts, and other information.

A mobile device is typically provided with at least one data processing entity 201 , at least one memory 202 and other possible components 203 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The data processing, storage and other relevant components can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 204. The user may control the operation of the mobile device by means of a suitable user interface, such as keypad 205, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 208, a speaker and a microphone can be also provided. Furthermore, a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.

The mobile device 200 may receive signals over an air or radio interface 207 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 2, a transceiver apparatus is designated schematically by block 206. The transceiver apparatus 206 may be provided, for example, by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally and/or externally to the mobile device.

Figure 3 shows an example of a control apparatus 300 for a communication system, for example to be coupled to and/or for controlling a station of an access system, such as a RAN node, e.g. a base station, eNB or gNB, a relay node or a core network node, such as an MME or Serving Gateway (S-GW) or Packet Data Network Gateway (P-GW), or a core network function, such as AMF/SMF, or a server or host. The method may be implemented in a single control apparatus or across more than one control apparatus. The control apparatus may be integrated with or external to a node or module of a core network or RAN. In some example embodiments, base stations comprise a separate control apparatus unit or module. In other example embodiments, the control apparatus can be another network element, such as a radio network controller or a spectrum controller. In some example embodiments, each base station may have such a control apparatus as well as a control apparatus being provided in a radio network controller. The control apparatus 300 can be arranged to provide control on communications in the service area of the system. The control apparatus 300 comprises at least one memory 301 , at least one data processing unit 302, 303 and an input/output interface 304. Via the interface the control apparatus can be coupled to a receiver and a transmitter of the base station. The receiver and/or the transmitter may be implemented as a radio front end or a remote radio head.

A majority of gNodeBs (gNBs) deployed worldwide are monolithic, e.g., the gNB is a single node containing protocol stack layers from the radio resource control (RRC) layer to the PHY layer in the control plane (and SDAP to PHY layer in the user plane). Monolithic solutions may not be necessary or desired in all scenarios and the concept of split gNB, which divides the protocol stack among two logical nodes has been introduced.

In a split gNB 5G architecture, focusing on the control plane (CP), the gNB-central unit (CLI) hosts the RRC and PDCP layers, while the gNB-distributed unit (DU) hosts the RLC, MAC, and PHY layers according to definitions in 3GPP standards. The CU may serve a plurality of DUs and may be located in remote sites with cloud infrastructures. The CU is responsible for mobility procedures in 5G. One feature of the split architecture is its ability to provide resource pooling gains and enhanced (e.g., efficient) scaling of computing capabilities. In 6G, the CU and DU responsibilities may be revisited, e.g., a future DU may have RRC capabilities similar to the ones described below or more.

The 5G CN implements a service-based architecture (SBA). The functions provided by each CN NF are categorized into services. Network functions (NFs) have URI/IP addresses and can contact each other if they have the necessary authorization, without having to go through additional hops/NFs as in previous generations employing point-to-point (P2P) interfaces. Additional hops may introduce latency and be energy inefficient.

Within split gNB architecture in 5G, the CU is the gNB logical node with a connection to the core network (CN). As specified in 3GPP standards, the CU has a P2P connection (NG interface) to the access and mobility management function (AMF) of the CN. Any message originating from the UE or DU to the AMF passes through the CU and vice versa. As a result, the CU may become a bottleneck for messages between the UE/DU and the AMF, for example, if the CU serves tens of DUs. An even larger number (in the order of hundreds) of DUs served by a CU is envisioned in future systems. A current architecture standard does not specify direct Dll-CN interfaces, but the introduction of SBA to RAN is being discussed as a possible solution for 6G. This introduction may allow direct Dll-CN communication using service-based interfaces (SBIs). This is another motivation for studying the benefits of direct Dll-CN communication.

It would be thus beneficial to analyze which type of messages can bypass the ClI (messages in which the CLI acts as a relay and doesn’t do any processing) and to describe in detail the required changes at the affected network entities, and the corresponding simplified procedures.

Figure 4 shows a flowchart of a method according to an example embodiment. The method many be performed at a distributed unit of an access node (such as gNB).

In 401 , the method comprises determining, at a distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the core network function.

In 402, the method comprises discovering the at least one core network function.

In 403, the method comprises receiving at least one control plane message of the at least one type of control plane messages from one of a user equipment and the at least one core network function at the distributed unit via a direct transport link between the distributed unit and the core network function.

In 404, the method comprises providing the received at least one control plane message to the other of the user equipment and the at least one core network function from the distributed unit via a direct transport link between the distributed unit and the core network function.

The plurality of types of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages. That is, the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

Figure 5 shows a flowchart of a method according to an example embodiment. The method may be performed at an apparatus associated with a core network function (or CN NF). The apparatus may be configured to operate as one or more CN NFs, such as an LMF and/or an AMF. For example, the apparatus may be configured to perform at least some actions of a first core network function (e.g., LMF) and/or at least some actions of a second core network function (e.g., AMF).

In 501 , the method comprises discovering, at a core network function, at least one distributed unit of at least one access node.

In 502, the method comprises receiving from, or providing to, the at least one distributed unit at least one control plane message of at least one type of control plane messages at the core network function via a direct transport link between the distributed unit and the core network function.

The at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

The DU and CN may be enabled to communicate directly with each other bypassing CU regarding at least UE registration messages, UE deregistration messages and UE positioning messages.

The method may enable (or otherwise facilitate/realize) direct DU-CN communications by assuming and extending an RRC split between DU and CU.

In an example embodiment, the DU has the processing capability to decode a UL RRC message header to know the message content final destination (e.g. AMF or CU). The DU is also able to form a DL RRC message to the UE. This is an example of receiving at least one control plane message of the at least one type of control plane messages from a user equipment at the distributed unit and providing the received at least one control plane message to the at least one core network function from the distributed unit.

This is in contrast to the current 5G system where the DU transparently forwards all UL RRC messages to the CU and all DL RRC messages to the UE.

The direct transport link may comprise a point-to-point application layer protocol or a service based interface (SBI). In an example embodiment, the interface between the DU and CN is realized with a dedicated P2P NGAP interfaces or with an SBI. A first option, which is an example of a point-to-point application layer protocol, is a P2P interface between DU and AMF.

A second option, which is an example of a SBI, is an extension of the SBA into the RAN nodes (DU and CU), thereby allowing the DU to contact the AMF (or any other core NF) via an SBI. This may require a cross (RAN-core) domain network repository function where the entities can register their functionalities as services. This enables (or otherwise facilitates/realizes) the DU to contact other CN NFs as well and vice versa, skipping the AMF (in addition to the CU) in case the AMF is acting as a transparent relay.

DU and CN may be enabled to discover each other which means that CN is aware of the DU- CU and DU-cell associations via proper identifiers as well as the DU being aware of the related CN NF addresses and performing address/identifier mapping. This is an example of discovering the at least one core network function (at the DU) or discovering at least one DU (at the core network function).

Discovering the at least one core network function at the DU may comprise obtaining core network function topology information at the distributed unit. The core network function topology information may comprise at least one of an identifier (ID) associated with the at least one core network function or an address (e.g., transport address) associated with the at least one core network function.

The core network function topology information may be configured at the distributed unit or may be received from at least one core network function or a centralised unit of the access node.

Discovering the at least one DU at the CN NF may comprise obtaining DU topology information at the CN NF. The DU topology information may comprise at least one of an identifier (ID) associated with the at least one DU or an address (e.g., transport address) associated with the at least one DU.

The DU topology information may be configured at the CN NF or may be received from at least one DU or a CU of the access node.

In an example embodiment, a 5G system architecture is modified to include means to obtain CN NF topology knowledge (IDs, transport addresses) at the DU, enabling (or otherwise facilitating/realizing) the DU to contact relevant CN NFs whenever necessary. The means may include proper configuration at DU (e.g., the CN NF topology information is configured at the DU) or via a registry functionality like NRF (in this case, the CN NF topology information is received from the CN NF or CU). The latter is for the case of SBA as described above.

In an example embodiment, a 5G system architecture is modified to include means to obtain DU topology knowledge (IDs, transport addresses) at the CN NFs, enabling (or otherwise facilitating/realizing) the CN NFs to contact the relevant DUs whenever necessary. The means may include proper configuration at relevant CN NFs (e.g., the DU topology information is configured at the CN NF) or via a registry functionality like NRF (in this case, the DU topology information is received from the DU or CU). The latter is for the case of SBA.

In the case where the at least one type of control plane messages comprise registration messages, the method may comprise providing a registration request message from the distributed unit to the at least one core network function via the direct transport link between the distributed unit and the core network function and receiving a registration accept message at the distributed unit from the at least one core network function via the direct transport link between the distributed unit and the core network function in response.

The method may further comprise receiving an identity request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and providing an identity response message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

The method may further comprise receiving an authentication request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and providing an authentication response message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

Figure 6 shows an example signalling flow for UE registration with enabled DU-CN communication. In this example embodiment, the CN NF is an AMF. By defining the AMF services that can be consumed at the DU and vice versa, the resulting procedure can be simplified. The messages in steps 3, 4, 7, 10, 14 and 21 bypass the CU.

In step 1 , the DU receives a registration request from a UE. In step 2, the DU selects an AMF.

In step 3, the DU sends a registration request to the AMF. This is an example of providing a registration request message from the distributed unit to the at least one core network function via the direct transport link between the distributed unit and the core network function.

Optionally, if SUCI is not provided by the UE, in step 4, the AMF sends an identity request to the DU. This is an example of receiving an identity request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function.

In step 5, the DU forwards the identity request to the UE and receives an identity response form the UE in step 6. The DU sends the identity response to the AMF is step 7. Step 7 is an example of providing an identity response message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

If required, the AMF sends an authentication request (for SUCI or SUPI) to AUSF in step 8 and the AUSF starts authentication in step 9. The AMF sends an authentication request to DU in step 10. This is an example of receiving an authentication request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function. The authentication request may be a EAP request or AKA challenge.

The DU sends the authentication request to the UE in step 11 . In step 12, the UE calculates the authentication response and sends an authentication response to the DU in step 13. In step 14, the DU sends the authentication response to the AMF. Step 14 is an example of providing an authentication request message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

In step 15, the AMF sends the authentication response to the AUSF. The AUSF verifies the response in step 16 and sends the authentication result (e.g., EAP success or anchor key KSEAF) to the AMF.

In step 18, the AMF sends the authentication result to the CU and the CU sends the authentication result to the DU in step 19. The DU sends the authentication result to the UE in step 20. The CU is notified of the authentication response by the AMF in step 18 as it contains authentication keys used for access stratum authentication by the CU.

In step 21 , the AMF sends a registration accept message to the DU and the DU sends the registration accept message to the UE in step 22. This is an example of receiving a registration accept message at the distributed unit from the at least one core network function via the direct transport link between the distributed unit and the core network function.

In the case where the at least one type of control plane messages comprises deregistration messages the method may comprise providing a deregistration request message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function and receiving a deregistration accept message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function.

Alternatively, in the case where the at least one type of control plane messages comprises deregistration messages, the method may comprise receiving the deregistration request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and providing the deregistration accept message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

Figures 7 and 8 show a signalling flow for UE-initiated deregistration and network-initiated deregistration, respectively, in a system with enabled DU-CN communications.

In step 1 of Figure 7, the UE provides a deregistration request to the DU. In step 2, the DU provides the deregistration request to the AMF. In step 3, the AMF provides a deregistration accept message to the DU and in step 4, the DU provides the deregistration accept message to the UE.

In step 1 of Figure 8, the AMF provides a deregistration request to the DU. In step 2, the DU provides the deregistration request to the UE. In step 3, the UE provides a deregistration accept message to the DU and in step 4, the DU provides the deregistration accept message to the AMF.

When the at least one type of control plane messages comprises positioning messages the method may comprise receiving a UE positioning capability request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, providing a UE positioning capability response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, receiving a positioning information request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, providing a positioning information response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, receiving a positioning activation request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function, providing a positioning activation response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function, receiving a positioning measurement request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and providing a positioning measurement response to the at least one core network function from the distributed unit to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

Figure 9 shows an example signalling flow for a UL positioning procedure in a system with enabled Dll-CN communication.

The CU acts as a transparent relay in the positioning procedure in the 5GS. The DU is the entity responsible for reporting of UE capabilities, setting up the over-the-air positioning procedure, and performing the actual measurements in step 7 (angle of arrival, relative time of arrival, etc.). These measurements are transmitted to the CU via the F1 interface which then transparently relays them to the CN in step 8.

Note that in the example embodiment shown in Figure 9, there is a direct link from the DU to the AMF (Option 1 of the direct transport link discussed above). In an alternative example embodiment, an SBA implementation (Option 2 of the direct transport link) allows direct DU- LMF communication where the AMF can be skipped in all messages.

Figure 9 shows a positioning procedure for UL methods (e.g. UL angle of arrival or TDOA methods). For DL AoD and DL TDoA methods, the measurements are done at the UE. Thus, the Positioning measurement response message is created at the UE and sent to the DU. Distributed NAS may be exploited here where the destination (LMF) can be included in the UE message (RRC header) when sending it to the DU. That way, the DU can forward the message to the LMF directly. The RAN handler (entity processing the NAS messages) here is the DU.

DU and CU can negotiate on which procedures each logical entity will handle. This is an example of determining, at a distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the core network function.

DU and CU may be enabled to negotiate on the messages that each will handle from and towards UE(s) either at fire up of the RAN logical entities or at registration of UE to the network.

The at least one type of control plane message of a plurality of control plane messages may be determined via F1 setup procedure if the negotiated procedures to be handled should cover all the cells/TRPs in the DU coverage. This is an example where the DU and CU are enabled to negotiate on the messages that each will handle at fire up of the RAN logical entities.

For example, determining, at the distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the at least one core network function may comprise providing control plane capabilities to a centralised unit of the access node from the distributed unit in an F1 setup request message and means for receiving, from the centralised unit at the distributed unit, an indication of accepted capabilities in an F1 setup response.

In this alternative, a CU-DU negotiation covers all UEs and cells. This means that the chosen entity to handle UE procedures to/from CN is the same for all UEs. Therefore, such decision can be done at the fire up of the DU, impacting the interface setup procedures.

In an example embodiment, as shown in step 1 of Figure 10, an F1 Setup Request from DU to CU includes control plane procedure capabilities of DU. Control plane procedure capabilities may comprise the control plane message that the DU can handle (e.g., process and forward to the core network or UE, bypassing the CU). CU has the mechanism to decide on which DU control plane capabilities it would accept to hand over and correspondingly the F1 Setup Response includes control plane procedure capabilities of DU that the CU accepts (e.g., accepted capabilities). Based on this both DU and CU can store their context either locally or at an external database (DB). If the storage is external the contexts may be stored with a proper key, such as CU-Dll Pair ID corresponding to a pair formation of ClI ID and DU ID. The ID may be used by both entities and the corresponding value it holds point to a list entry with CU Context and DU Context.

When UE(s) enters such an area where DU and CU negotiated to split the handling of messages for all UEs, the UE contexts may be saved internally in each entity (DU and CU) or externally at a database with a proper key, such as UE ID. UE ID can be different for each entity. Each entity may share/synchronize the UE context with each other. This may be done via 1 ) in case of internal or external storage of UE context, CU-DU interface interaction carrying the UE context or 2) in case of external database use for UE context storage, the key sharing over CU-DU interface and UE context can be fetched from the database.

Figure 10 shows an example signalling flow for DU and CU negotiation of control plane message type at fire up.

In step 1 , the DU sends a F1 setup request including an indication of control plane capabilities that DU can handle. In step 2, the DU receives a F1 setup response including an indication of control plane procedure capabilities that CU accepts (e.g., accepted capabilities).

The at least one type of control plane message of a plurality of control plane messages may be determined via RRC transfer procedure if the negotiated procedures to be handled should be decided on a per UE or per slice per UE basis.

For example, determining, at the distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the at least one core network function may comprises providing control plane capabilities associated with the user equipment or a slice of the user equipment to a centralised unit of the access node from the distributed unit in a UE registration message and means for receiving from the centralised unit at the distributed unit an indication of accepted capabilities associated with the user equipment or a slice of the user equipment in a UE registration response message.

Figure 11 shows an example signalling flow for DU and CU negotiation of control plane message type at UE registration. In step 1 , the DU sends an UL RRC message including an indication of control plane capabilities that DU can handle for a UE or for a slice of the UE. In step 2, the DU receives a DL RRC message including an indication of control plane procedure capabilities that CU accepts (e.g., accepted capabilities) for the UE or for the slice of the UE.

In the example embodiment as described with reference to Figure 11 , CU-DU negotiation customized per UE or per UE per slice, etc. This can be advantageous in cases where the served UE(s) in a DU area consume different services with varying service requirements. Therefore, such decision may be done at the UE registration, impacting the RRC message transfer messages.

As shown in step 1 of Figure 11 , when UE sends a RRC Setup Request to a DU, DU initiates UL RRC Message Transfer procedure towards CU including the control plane procedure capabilities of DU. CU has the mechanism to decide on which DU control plane capabilities it would accept to handover and correspondingly the DL RRC Message Transfer procedure towards DU includes control plane procedure capabilities of DU that the CU accepts. Based on the decision the corresponding messages to CN are either handled by DU or CU. Based on this, once the UE context is created, both DU and CU may store the UE context either locally or at an external database. If the storage is external the contexts are stored with a proper key, such as CU-DU Pair UE ID corresponding to a pair formation of CU ID, DU ID and UE ID. The pair ID may be used by both entities as well as CN and the corresponding value it holds point to UE Context. Formation of the ID may follow similar principles as the RAN UE NGAP ID.

DU and CU may be enabled to renegotiate on the messages that each will handle from and towards UE(s) via reconfiguration of the RAN logical entities or UE context management procedures.

In an example embodiment, DU and CU may renegotiate on which procedures (e.g., control plane message type) each logical entity will handle which may happen based on operator policies, UE RRC state transition, UE mobility, etc. This can be done via gNB-DU Configuration Update and gNB-CU Configuration Update procedures if the negotiated procedures to be handled should cover all the cells/TRPs in the DU coverage or via RRC transfer procedures if the negotiated procedures to be handled should be decided on a per UE or per slice basis. The updated procedures may include the same information as the negotiation cases (e.g., inclusion of control plane capabilities of DU, acceptance/rejection of set of control plane capabilities of DU, DB storage of the relevant context). The UE/RAN Node context stored with the proper ID is updated by either entity. Any entity subscribed to receive notifications on the updates on the UE/RAN Node context receives the updated information.

In an example embodiment, for the CN to be aware that the UE is being handled by two different end points (CU or DU) for e.g., enabling stability and avoiding duplicate signaling in the system, a mechanism that allows a mapping of the different UE IDs between DU-CN and CU-CN should be in place. This may be done during registration where the RAN logical entity that handles the registration procedure can let the CN know in its message that another RAN logical entity is also responsible for handling the UE towards the CN, e.g., with a binary flag “dual handling of UE enabled” and the identifier for the entities, such as CU-DU ID pair. CN may then generate two UE IDs and contact each entity to provide the separate IDs in different messages. CN can store this mapping information and use it to handle the UE with the correct RAN logical entity.

Methods as described with reference to Figures 4 to 11 may provide, among other things, procedural simplification and reduce latency, unnecessary signaling as well as computational complexity at the CU. The direct communication between the DU and the CN may contribute towards achieving a flexible architecture for 6G and reduce unnecessary hierarchy for a flat architecture for 6G.

An apparatus may comprise means for determining, at a distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the core network function, means for discovering the at least one core network function, means for receiving at least one control plane message of the at least one type of control plane messages from one of a user equipment, UE, and the at least one core network function at the distributed unit via a direct transport link between the distributed unit and the core network function and means for providing the received at least one control plane message from the distributed unit to the other of the user equipment and the at least one core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

The apparatus may comprise a distributed unit of a gNB, be the DU or be comprised in the DU or a chipset for performing at least some actions of/for the DU. Alternatively, or in addition, an apparatus may comprise means for discovering, at a core network function, at least one distributed unit of at least one access node and receiving from, or providing to, the at least one distributed unit at least one control plane message of at least one type of control plane messages from at the core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

The apparatus may be configured to operate as one or more core network functions, such as an AMF and/or LMF. For example, the apparatus may be configured to perform at least some actions of a first core network function (e.g., AMF) and/or at least some actions of a second core network function (e.g., LMF).

It should be understood that the apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and/or reception. Although the apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities.

It is noted that whilst some example embodiments have been described in relation to 5G networks, similar aspects can be applied in relation to other networks and communication systems, such as 6G networks or 5G-Advanced networks. Therefore, although certain example embodiments were described above, by way of example, with reference to certain example architectures for wireless networks, technologies and standards, example embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein.

It is also noted herein that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of this disclosure.

It shall be understood that although the terms “first,” “second” and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of the various example embodiments. As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” and similar expressions, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements. As used herein, the expression “and/or” means at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

As used herein, unless to explicitly stated to the contrary, performing a step/operation/functionality “in response to A” does not indicate that the step/operation/functionality is performed immediately after “A” occurs as one or more intervening steps/operations/functionalities may be included therebetween. Analogously, performing a step/operation/functionality “based on A” does not indicate that the step/operation/functionality is performed solely based on “A”, as the referenced step/operation/functionality may be further based on one or more other conditions (such as “B”) in addition to “A”.

In general, the various embodiments may be implemented in hardware or special purpose circuitry, software, logic or any combination thereof. Some aspects of the disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

As used herein, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable):

(i) a combination of analog and/or digital hardware circuit(s) with software/firmware and

(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and I hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.”

This definition of circuitry applies to all uses of this term herein, including in any claims. As a further example, as used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

The various example embodiments of this disclosure may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and/or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computer-executable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it.

Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The physical media is a non-transitory media. The term “non-transitory,” as used herein, is a limitation of the medium itself (e.g., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

Example embodiments of the disclosure may be practiced in various components, such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

The scope of protection sought for various example embodiments of the disclosure is set out by the independent claims. The example embodiments, aspects and features thereof, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various example embodiments of the disclosure.

The foregoing description has provided by way of non-limiting examples a full and informative description of the various embodiments of this disclosure. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the claims. However, all such and similar modifications of the teachings of this disclosure will still fall within the scope of this disclosure as defined in the claims. Indeed, there is a further example embodiment comprising a combination of one or more example embodiments with any of the other example embodiments discussed herein.

Claims

1 . An apparatus comprising: means for determining, at a distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the core network function; means for discovering the at least one core network function; means for receiving at least one control plane message of the at least one type of control plane messages from one of a user equipment, LIE, and the at least one core network function at the distributed unit via a direct transport link between the distributed unit and the core network function; and means for providing the received at least one control plane message from the distributed unit to the other of the user equipment and the at least one core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

2. The apparatus according to claim 1 , wherein the direct transport link comprises a point-to-point application layer protocol or a service based interface.

3. The apparatus according to any of claim 1 or claim 2, wherein the at least one type of control plane messages comprises LIE registration messages and comprising: means for providing a LIE registration request message from the distributed unit to the at least one core network function via the direct transport link between the distributed unit and the core network function; and means for receiving a LIE registration accept message at the distributed unit from the at least one core network function via the direct transport link between the distributed unit and the core network function.

4. The apparatus according to claim 3, comprising means for receiving a LIE identity request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and means for providing a LIE identity response message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

5. The apparatus according to claim 3 or claim 4, comprising means for receiving a LIE authentication request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and means for providing a UE authentication response message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

6. The apparatus according to any of claims 1 to 5, wherein the at least one type of control plane messages comprises UE deregistration messages and comprising: means for providing a UE deregistration request message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function and means for receiving a UE deregistration accept message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function; or means for receiving the UE deregistration request message from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function and means for providing the UE deregistration accept message to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

7. The apparatus according to any of claims 1 to 6, wherein the at least one core network function comprises an access and mobility and management function.

8. The apparatus according to any of claims 1 to 6, wherein the at least one type of control plane messages comprises positioning messages and comprising: means for receiving a UE positioning capability request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function; means for providing a UE positioning capability response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function; means for receiving a positioning information request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function; means for providing a positioning information response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function; means for receiving a positioning activation request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function; means for providing a positioning activation response to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function; means for receiving a positioning measurement request from the at least one core network function at the distributed unit via the direct transport link between the distributed unit and the core network function; and means for providing a positioning measurement response to the at least one core network function from the distributed unit to the at least one core network function from the distributed unit via the direct transport link between the distributed unit and the core network function.

9. The apparatus according to any of claims 1 to 2 and 8 wherein the at least one core network function is an access and mobility management function or a location management function.

10. The apparatus according to any of claims 1 to 9, wherein means for discovering the at least one core network function comprises means for obtaining core network function topology information at the distributed unit.

11 . The apparatus according to claim 10, wherein the core network function topology information comprises at least one of an identifier associated with the at least one core network function or an address associated with the at least one core network function.

12. The apparatus according to claim 10 or claim 11 , wherein the core network function topology information is configured at the distributed unit or comprising means for receiving the core network function topology information from at least one core network function or a centralised unit of the access node.

13. The apparatus according to any of claims 1 to 12 wherein means for determining, at the distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the at least one core network function comprises means for providing control plane capabilities to a centralised unit of the access node from the distributed unit in an F1 setup request message and means for receiving, from the centralised unit at the distributed unit, an indication of accepted capabilities in an F1 setup response.

14. The apparatus according to any of claims 1 to 12, wherein means for determining, at the distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the at least one core network function comprises means for providing control plane capabilities associated with the user equipment or a slice of the user equipment to a centralised unit of the access node from the distributed unit in a LIE registration message and means for receiving from the centralised unit at the distributed unit an indication of accepted capabilities associated with the user equipment or a slice of the user equipment in a LIE registration response message.

15. An apparatus comprising: means for discovering, at a core network function, at least one distributed unit of at least one access node; and means for receiving from, or providing to, the at least one distributed unit at least one control plane message of at least one type of control plane messages at the core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

16. The apparatus according to claim 15, comprising means for receiving the at least one control plane message from the distributed unit at the at least one core network function via a point-to-point application layer protocol or a service based interface.

17. The apparatus according to claim 15 or claim 16, wherein the at least one core network function is an access and mobility management function or a location management function.

18. The apparatus according to any of claims 15 to 17, wherein means for discovering the at least one core distributed unit comprises means for obtaining distributed unit topology information at the core network function.

19. The apparatus according to claim 18, wherein the distributed unit topology information comprises at least one of an identifier associated with the at least one distributed unit or an address associated with the at least one distributed unit.

20. The apparatus according to claim 18 or claim 19, wherein the distributed unit topology information is configured at the core network function or comprising means for receiving the distributed unit topology information from at least one distributed unit or a centralised unit of the access node.

21 . A method comprising: determining, at a distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the core network function; discovering the at least one core network function; receiving at least one control plane message of the at least one type of control plane messages from one of a user equipment, LIE, and the at least one core network function at the distributed unit via a direct transport link between the distributed unit and the core network function; and providing the received at least one control plane message from the distributed unit to the other of the user equipment and the at least one core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

22. A method comprising: discovering, at a core network function, at least one distributed unit of at least one access node; and receiving from, or providing to, the at least one distributed unit at least one control plane message of at least one type of control plane messages at the core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

23. An apparatus comprising: at least one processor, and at least one memory storing instructions which, when executed by the processor, cause the apparatus at least to: determine, at a distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the core network function; discover the at least one core network function; receive at least one control plane message of the at least one type of control plane messages from one of a user equipment, LIE, and the at least one core network function at the distributed unit via a direct transport link between the distributed unit and the core network function; and provide the received at least one control plane message from the distributed unit to the other of the user equipment and the at least one core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

24. An apparatus comprising: at least one processor, and at least one memory storing instructions which, when executed by the processor, cause the apparatus at least to: discover, at a core network function, at least one distributed unit of at least one access node; and receive from, or provide to, the at least one distributed unit at least one control plane message of at least one type of control plane messages at the core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

25. A computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: determining, at a distributed unit of an access node, at least one type of control plane message of a plurality of types of control plane messages to send to at least one core network function via a direct transport link between the distributed unit and the core network function; discovering the at least one core network function; receiving at least one control plane message of the at least one type of control plane messages from one of a user equipment, LIE, and the at least one core network function at the distributed unit via a direct transport link between the distributed unit and the core network function; and providing the received at least one control plane message from the distributed unit to the other of the user equipment and the at least one core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.

26. A computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: discovering, at a core network function, at least one distributed unit of at least one access node; and receiving from, or providing to, the at least one distributed unit at least one control plane message of at least one type of control plane messages at the core network function via a direct transport link between the distributed unit and the core network function, wherein the at least one type of control plane messages comprises at least one of the following: registration messages, deregistration messages or positioning messages.