GB2632437A

GB2632437A - Method, apparatus and computer program

Info

Publication number: GB2632437A
Application number: GB2312103.1A
Authority: GB
Inventors: Liebhart Rainer; Chandramouli Devaki; Thiebaut Laurent
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2023-08-08
Filing date: 2023-08-08
Publication date: 2025-02-12
Also published as: GB202312103D0; WO2025031719A1

Abstract

There is provided a method performed at a user equipment, the method comprising: receiving, from a first node providing a first cell, a cluster identifier for a cluster comprising the first node providing the first cell, a second node providing a second cell, and a cluster node; and sending a connection establishment request to the first node or via the first node to the cluster node indicating a cluster connection request; or sending a handover request to the first node upon mobility into the first cell; or storing the cluster identifier for subsequent use when camping in a cell within the cluster.

Description

METHOD, APPARATUS AND COMPUTER PROGRAM

FIELD

The present application relates to methods, apparatuses, systems and computer programs and in particular but not exclusively to enabling user equipment connectivity to and switching of user plane traffic within a cluster of radio nodes.

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. Non-limiting 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 typically 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 UTRAN (3G radio). Other examples of communication systems are the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology, so-called 5G or New Radio (NR) networks or future 6G networks. NR is being standardized by the 3rd Generation Partnership Project (3GPP).

SUMMARY

According to an aspect, there is provided a user equipment comprising means for: receiving, from a first node providing a first cell, a cluster identifier for a cluster comprising the first node providing the first cell, a second node providing a second cell, and a cluster node; and sending a connection establishment request to the first node or via the first node to the cluster node indicating a cluster connection request; or sending a handover request to the first node upon mobility into the first cell; or storing the cluster identifier for subsequent use when camping in a cell within the cluster.

The receiving may comprise: receiving the cluster identifier as broadcast information in the first cell; or receiving at least one of the cluster identifier and the user equipment's cluster identifier in a signalling dedicated to the user equipment, wherein the cluster identifier is unique to the cluster and the user equipment's cluster identifier is unique to the user equipment.

The user equipment may further comprise means for: determining that the user equipment has entered the coverage area of the cluster based on receiving the cluster identifier; and in response to the determining: sending the connection establishment request to the first node or via the first node to the cluster node indicating the cluster connection request; or sending the handover request to the first node.

The user equipment may further comprise means for: receiving, from the first node or from the cluster node, the user equipment's cluster identifier of the user equipment as part of a connection establishment initiated by the first node or cluster node for a hand-over towards the cluster.

The user equipment may further comprise means for: receiving, from the first node or from the cluster node, the user equipment's cluster identifier of the user equipment as part of a connection establishment with the first node or with the cluster node.

The user equipment may further comprise means for: receiving, from the first node, a destination layer 2 address to provide in uplink user plane packets sent by the user equipment to the cluster.

The layer 2 address may comprise a medium access control address.

The user equipment may further comprise means for: sending, to a session management function via the first node, a protocol data unit session request comprising information indicating a support of internet protocol with layer 2 transport; and receiving, from the session management function via the first node, a response indicating that a protocol data unit session providing internet protocol connectivity has been established with usage of layer 2 transport within the cluster.

The protocol data unit session request may further comprise information indicating a layer 2 address of the user equipment.

The user equipment may further comprise means for: determining that the user equipment has entered the coverage area of the second cell; and in response to determining that the user equipment has entered the coverage area of the second cell, executing signalling with the first node and second node to establish a connection to the second node and terminating the connection with the first node, wherein the signalling comprises the user equipment's cluster identifier of the user equipment or a layer 2 address of the user equipment.

Executing the signalling may comprise executing the signalling with the first node and the second node and the cluster node to establish the connection to the second node and terminating the connection with the first node, wherein the signalling may comprise the user equipment's cluster identifier of the user equipment or a layer 2 address of the user equipment.

The user equipment may further comprise means for: sending, via the second node, one or more uplink data packets including a layer 2 address of the user equipment and/or receiving, via the second node, one or more downlink data packets.

The one or more uplink data packets may further comprise a destination address of a target user plane function, or may further comprise an identifier mapping to the destination address of a target user plane function.

The user equipment may further comprise means for: receiving the destination address of the target user plane function via a control plane, for example non-access stratum signalling or radio resource control signalling, or via a user plane procedure.

According to an aspect there is provided a cluster node of a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node, the cluster node comprising means for: receiving, from the first or second node, one or more uplink data packets comprising a destination address of a target user plane function and information indicating a layer 2 address of a user equipment; determining that the layer 2 address of the user equipment is served by one of the first or second node which is reachable via a transmission link over which said one or more uplink data packets have been received; and storing an association between the layer 2 address of the user equipment and the transmission link.

The cluster node may further comprise means for: receiving one or more downlink data packets addressed to the user equipment; based on the information indicating the layer 2 address of the user equipment and on the stored transmission link associated with the layer 2 address of the user equipment, determining the transmission link on which to send downlink data packets addressed to the user equipment; and sending the received one or more downlink data packets on the determined link.

The cluster node may further comprise means for: sending, to the target user plane function and based on the destination address, the one or more uplink data packets.

According to an aspect there is provided a cluster node of a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node, the cluster node comprising means for: receiving, from a user equipment via the first cell, a connection request for a user equipment; based on the user equipment connection request, sending, to the user equipment via the first node, a connection response comprising the user equipment's cluster identifier for the user equipment; and generating user equipment specific context data comprising the user equipment's cluster identifier for the user equipment.

The user equipment specific context data may be stored in a database accessible by at least the first node and the second node.

The cluster node may further comprise means for sending, to the first node and the second node, the user equipment specific context data.

The connection request may comprise a unique layer 2 address of the user equipment.

The cluster node may further comprise means for: receiving, from the user equipment via the first node, a protocol data unit session request for the user equipment, the request comprising information indicating a support of internet protocol with layer 2 transport; based on the protocol data unit session request, establishing a protocol data session providing internet protocol connectivity with usage of layer 2 transport within the cluster; and sending, to the user equipment via the first node, a message indicating that a protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established.

The cluster node may further comprise means for: receiving, from the first node, a request for user equipment specific context data; and in response to receiving the request for the user equipment specific context data, sending, to the first node, the generated user equipment context data.

The cluster node may further comprise means for: receiving, from the first node or the second node, information indicating a change in the user equipment specific context data; and updating the user equipment specific context data stored at the cluster node based on the received information.

The cluster node may further comprise means for: receiving, from the second node, information indicating the layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment.

The cluster node may further comprise means for: binding the layer 2 address of the user equipment to an outgoing port of the cluster node or a signalling path or network information or to the second node.

According to an aspect, there is provided a first node of a cluster comprising the first node providing a first cell, a second node providing a second cell, and a cluster node, the first node comprising means for: sending, to a user equipment, a cluster identifier for the cluster; and receiving, from the user equipment, a connection establishment request indicating a cluster connection request; or receiving, from the user equipment, a handover request indicating handover into the cluster.

The sending may comprise sending the cluster identifier as broadcast information in the first cell or in signalling dedicated to the user equipment.

The first node may further comprise means for: based on the connection establishment request, establishing a connection to user equipment; determining a layer 2 address of the user equipment; and sending, to at least the cluster node and the second node, information indicating the layer 2 address of the user equipment.

The first node may further comprise means for: sending, to the user equipment, the user equipment's cluster identifier of the user equipment as part of a connection establishment with the user equipment.

The first node may further comprise means for: sending, to the user equipment, a destination layer 2 address to provide in uplink user plane packets sent by the user equipment to the cluster.

The layer 2 address may comprise a medium access control address.

Determining the layer 2 address of the user equipment may comprise receiving the layer 2 address from the user equipment.

The first node may further comprise means for: determining a change in user equipment specific context data; and sending, to the cluster node, information indicating the change in user equipment specific context data.

The sending may further comprise sending the information indicating the change in user equipment specific context data to the second node.

The first node may further comprise means for: receiving, from the user equipment, a protocol data unit session request comprising information indicating a support of internet protocol with layer 2 transport; sending, to the cluster node, the protocol data unit session request comprising the information indicating the support of internet protocol with layer 2 transport; receiving, from the cluster node, a response indicating that the requested protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established; and sending, to the user equipment, the response indicating that the requested protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established.

According to an aspect, there is provided a second node of a cluster comprising a first node providing a first cell, the second node providing a second cell, and a cluster node, the second node comprising means for: receiving, from the cluster node, user equipment specific context data associated with a user equipment's cluster identifier for the user equipment; receiving, from the user equipment, signalling messages when the user equipment is in the coverage area of the second cell, wherein the signalling comprises the user equipment's cluster identifier for the user equipment and a layer 2 address of the user equipment; determining the user equipment specific context data based on the user equipment specific context data received from the cluster node and the user equipment's cluster identifier of the user equipment received from the user equipment; and establishing a connection to the user equipment based on the determined user equipment specific context data.

The second node may further comprise means for: determining that the user equipment has connected to the second node; determining the layer 2 address of the user equipment; sending, to at least the cluster node and the first node, information indicating the layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment; and omitting tunnel switching between the first node and the second node due to handover.

Determining that the user equipment has connected to the second node may be based on signalling received from at least one of the user equipment, the first node, the cluster node, or other network node.

The second node may further comprise means for: determining a change in user equipment specific context data; and sending, to the cluster node, information indicating the change in user equipment specific context data.

The sending may further comprise sending the information indicating the change in user equipment specific context data to the first node.

The second node may further comprise means for: after establishing the connection to the user equipment, sending, to at least the cluster node and the first node, information indicating a change in layer 2 address of the user equipment.

The second node may further comprise means for: receiving, from the user equipment, one or more uplink data packets comprising a destination address of a target user plane function; and sending, to the cluster node, the one or more uplink data packets comprising the destination address of the target user plane function and information indicating a layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment.

According to an aspect, there is provided a user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the user equipment at least to: receive, from a first node providing a first cell, a cluster identifier for a cluster comprising the first node providing the first cell, a second node providing a second cell, and a cluster node; and send a connection establishment request to the first node or via the first node to the cluster node indicating a cluster connection request; or send a handover request to the first node upon mobility into the first cell; or store the cluster identifier for subsequent use when camping in a cell within the cluster.

The at least one processor may be further configured to cause the user equipment to: receive the cluster identifier as broadcast information in the first cell; or receive at least one of the cluster identifier and the user equipment's cluster identifier in a signalling dedicated to the user equipment, wherein the cluster identifier is unique to the cluster and the user equipment's cluster identifier is unique to the user equipment.

The at least one processor may be further configured to cause the user equipment to: determine that the user equipment has entered the coverage area of the cluster based on receiving the cluster identifier; and in response to the determining: send the connection establishment request to the first node or via the first node to the cluster node indicating the cluster connection request; or send the handover request to the first node.

The at least one processor may be further configured to cause the user equipment to: receive, from the first node or from the cluster node, the user equipment's cluster identifier of the user equipment as part of a connection establishment initiated by the first node or cluster node for a hand-over towards the cluster.

The at least one processor may be further configured to cause the user equipment to: receive, from the first node or from the cluster node, the user equipment's cluster identifier of the user equipment as part of a connection establishment with the first node or with the cluster node.

The at least one processor may be further configured to cause the user equipment to: receive, from the first node, a destination layer 2 address to provide in uplink user plane packets sent by the user equipment to the cluster.

The layer 2 address may comprise a medium access control address.

The at least one processor may be further configured to cause the user equipment to: send, to a session management function via the first node, a protocol data unit session request comprising information indicating a support of internet protocol with layer 2 transport; and receive, from the session management function via the first node, a response indicating that a protocol data unit session providing internet protocol connectivity has been established with usage of layer 2 transport within the cluster.

The at least one processor may be further configured to cause the user equipment to: determine that the user equipment has entered the coverage area of the second cell; and in response to determining that the user equipment has entered the coverage area of the second cell, execute signalling with the first node and second node to establish a connection to the second node and terminate the connection with the first node, wherein the signalling comprises the user equipment's cluster identifier of the user equipment or a layer 2 address of the user equipment.

The at least one processor may be further configured to cause the user equipment to execute the signalling with the first node and the second node and the cluster node to establish the connection to the second node and terminate the connection with the first node, wherein the signalling may comprise the user equipment's cluster identifier of the user equipment or a layer 2 address of the user equipment.

The at least one processor may be further configured to cause the user equipment to: send, via the second node, one or more uplink data packets including a layer 2 address of the user equipment and/or receiving, via the second node, one or more downlink data packets.

The at least one processor may be further configured to cause the user equipment to: receive the destination address of the target user plane function via a control plane, for example non-access stratum signalling or radio resource control signalling, or via a user plane procedure.

According to an aspect, there is provided a cluster node of a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node, the cluster node comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the cluster node at least to: receive, from the first or second node, one or more uplink data packets comprising a destination address of a target user plane function and information indicating a layer 2 address of a user equipment; determine that the layer 2 address of the user equipment is served by one of the first or second node which is reachable via a transmission link over which said one or more uplink data packets have been received; and store an association between the layer 2 address of the user equipment and the transmission link.

The at least one processor may be further configured to cause the cluster node to: receive one or more downlink data packets addressed to the user equipment; based on the information indicating the layer 2 address of the user equipment and on the stored transmission link associated with the layer 2 address of the user equipment, determine the transmission link on which to send downlink data packets addressed to the user equipment; and send the received one or more downlink data packets on the determined link.

The at least one processor may be further configured to cause the cluster node to: send, to the target user plane function and based on the destination address, the one or more uplink data packets.

According to an aspect, there is provided a cluster node of a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node, the cluster node comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the cluster node at least to: receive, from a user equipment via the first cell, a connection request for a user equipment; based on the user equipment connection request, send, to the user equipment via the first node, a connection response comprising the user equipment's cluster identifier for the user equipment; and generate user equipment specific context data comprising the user equipment's cluster identifier for the user equipment.

The at least one processor may be further configured to cause the cluster node to: send, to the first node and the second node, the user equipment specific context data.

The at least one processor may be further configured to cause the cluster node to: receive, from the user equipment via the first node, a protocol data unit session request for the user equipment, the request comprising information indicating a support of internet protocol with layer 2 transport; based on the protocol data unit session request, establish a protocol data session providing internet protocol connectivity with usage of layer 2 transport within the cluster; and send, to the user equipment via the first node, a message indicating that a protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established.

The at least one processor may be further configured to cause the cluster node to: receive, from the first node, a request for user equipment specific context data; and in response to receiving the request for the user equipment specific context data, send, to the first node, the generated user equipment context data.

The at least one processor may be further configured to cause the cluster node to: receive, from the first node or the second node, information indicating a change in the user equipment specific context data; and update the user equipment specific context data stored at the cluster node based on the received information.

The at least one processor may be further configured to cause the cluster node to: receive, from the second node, information indicating the layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment.

The at least one processor may be further configured to cause the cluster node to: bind the layer 2 address of the user equipment to an outgoing port of the cluster node or a signalling path or network information or to the second node.

According to an aspect, there is provided a first node of a cluster comprising the first node providing a first cell, a second node providing a second cell, and a cluster node, the first node comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the first node at least to: send, to a user equipment, a cluster identifier for the cluster; and receive, from the user equipment, a connection establishment request indicating a cluster connection request; or receive, from the user equipment, a handover request indicating handover into the cluster.

The at least one processor may be further configured to cause the first node to send the cluster identifier as broadcast information in the first cell or in signalling dedicated to the user equipment.

The at least one processor may be further configured to cause the first node to: based on the connection establishment request, establish a connection to user equipment; determine a layer 2 address of the user equipment; and send, to at least the cluster node and the second node, information indicating the layer 2 address of the user equipment.

The at least one processor may be further configured to cause the first node to: send, to the user equipment, the user equipment's cluster identifier of the user equipment as part of a connection establishment with the user equipment.

The at least one processor may be further configured to cause the first node to: send, to the user equipment, a destination layer 2 address to provide in uplink user plane packets sent by the user equipment to the cluster.

The layer 2 address may comprise a medium access control address.

The at least one processor may be further configured to cause the first node to receive the layer 2 address from the user equipment.

The at least one processor may be further configured to cause the first node to: determine a change in user equipment specific context data; and send, to the cluster node, information indicating the change in user equipment specific context data.

The at least one processor may be further configured to cause the first node to send the information indicating the change in user equipment specific context data to the second node.

The at least one processor may be further configured to cause the first node to: receive, from the user equipment, a protocol data unit session request comprising information indicating a support of internet protocol with layer 2 transport; send, to the cluster node, the protocol data unit session request comprising the information indicating the support of internet protocol with layer 2 transport; receive, from the cluster node, a response indicating that the requested protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established; and send, to the user equipment, the response indicating that the requested protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established.

According to an aspect, there is provided a second node of a cluster comprising the first node providing a first cell, the second node providing a second cell, and a cluster node, the second node comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the first node at least to: receive, from the cluster node, user equipment specific context data associated with a user equipment's cluster identifier for the user equipment; receive, from the user equipment, signalling messages when the user equipment is in the coverage area of the second cell, wherein the signalling comprises the user equipment's cluster identifier for the user equipment and a layer 2 address of the user equipment; determining the user equipment specific context data based on the user equipment specific context data received from the cluster node and the user equipment's cluster identifier of the user equipment received from the user equipment; and establishing a connection to the user equipment based on the determined user equipment specific context data.

The at least one processor may be further configured to cause the second node to: determine that the user equipment has connected to the second node; determine the layer 2 address of the user equipment; send, to at least the cluster node and the first node, information indicating the layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment; and omit tunnel switching between the first node and the second node due to handover.

The at least one processor may be further configured to cause the second node to determine that the user equipment has connected to the second node based on signalling received from at least one of: the user equipment, the first node, the cluster node, or other network node.

The at least one processor may be further configured to cause the second node to: determine a change in user equipment specific context data; and send, to the cluster node, information indicating the change in user equipment specific context data.

The at least one processor may be further configured to cause the second node to send the information indicating the change in user equipment specific context data to the first node.

The at least one processor may be further configured to cause the second node to: after establishing the connection to the user equipment, send, to at least the cluster node and the first node, information indicating a change in layer 2 address of the user equipment.

The at least one processor may be further configured to cause the second node to: receive, from the user equipment, one or more uplink data packets comprising a destination address of a target user plane function; and send, to the cluster node, the one or more uplink data packets comprising the destination address of the target user plane function and information indicating a layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment.

According to an aspect, there is provided a method performed at a user equipment, the method comprising: receiving, from a first node providing a first cell, a cluster identifier for a cluster comprising the first node providing the first cell, a second node providing a second cell, and a cluster node; and sending a connection establishment request to the first node or via the first node to the cluster node indicating a cluster connection request; or sending a handover request to the first node upon mobility into the first cell; or storing the cluster identifier for subsequent use when camping in a cell within the cluster.

The method may further comprise: determining that the user equipment has entered the coverage area of the cluster based on receiving the cluster identifier; and in response to the determining: sending the connection establishment request to the first node or via the first node to the cluster node indicating the cluster connection request; or sending the handover request to the first node.

The method may further comprise: receiving, from the first node or from the cluster node, the user equipment's cluster identifier of the user equipment as part of a connection establishment initiated by the first node or cluster node for a hand-over towards the cluster.

The method may further comprise: receiving, from the first node or from the cluster node, the user equipment's cluster identifier of the user equipment as part of a connection establishment with the first node or with the cluster node.

The method may further comprise: receiving, from the first node, a destination layer 2 address to provide in uplink user plane packets sent by the user equipment to the cluster.

The layer 2 address may comprise a medium access control address.

The method may further comprise: sending, to a session management function via the first node, a protocol data unit session request comprising information indicating a support of internet protocol with layer 2 transport; and receiving, from the session management function via the first node, a response indicating that a protocol data unit session providing internet protocol connectivity has been established with usage of layer 2 transport within the cluster.

The method may further comprise: determining that the user equipment has entered the coverage area of the second cell; and in response to determining that the user equipment has entered the coverage area of the second cell, executing signalling with the first node and second node to establish a connection to the second node and terminating the connection with the first node, wherein the signalling comprises the user equipment's cluster identifier of the user equipment or a layer 2 address of the user equipment.

The method may further comprise: sending, via the second node, one or more uplink data packets including a layer 2 address of the user equipment and/or receiving, via the second node, one or more downlink data packets.

The method may further comprise: receiving the destination address of the target user plane function via a control plane, for example non-access stratum signalling or radio resource control signalling, or via a user plane procedure.

According to an aspect there is provided a method performed at cluster node of a cluster comprising a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node, the method comprising: receiving, from the first or second node, one or more uplink data packets comprising a destination address of a target user plane function and information indicating a layer 2 address of a user equipment; determining that the layer 2 address of the user equipment is served by one of the first or second node which is reachable via a transmission link over which said one or more uplink data packets have been received; and storing an association between the layer 2 address of the user equipment and the transmission link.

The method may further comprise: receiving one or more downlink data packets addressed to the user equipment; based on the information indicating the layer 2 address of the user equipment and on the stored transmission link associated with the layer 2 address of the user equipment, determining the transmission link on which to send downlink data packets addressed to the user equipment; and sending the received one or more downlink data packets on the determined link.

The method may further comprise: sending, to the target user plane function and based on the destination address, the one or more uplink data packets.

According to an aspect there is provided a method performed at a cluster node of a cluster comprising a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node, the method comprising: receiving, from a user equipment via the first cell, a connection request for a user equipment; based on the user equipment connection request, sending, to the user equipment via the first node, a connection response comprising the user equipment's cluster identifier for the user equipment; and generating user equipment specific context data comprising the user equipment's cluster identifier for the user equipment.

The cluster node may further comprise means for: sending, to the first node and the second node, the user equipment specific context data.

The method may further comprise: receiving, from the user equipment via the first node, a protocol data unit session request for the user equipment, the request comprising information indicating a support of internet protocol with layer 2 transport; based on the protocol data unit session request, establishing a protocol data session providing internet protocol connectivity with usage of layer 2 transport within the cluster; and sending, to the user equipment via the first node, a message indicating that a protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established.

The method may further comprise: receiving, from the first node, a request for user equipment specific context data; and in response to receiving the request for the user equipment specific context data, sending, to the first node, the generated user equipment context data.

The method may further comprise: receiving, from the first node or the second node, information indicating a change in the user equipment specific context data; and updating the user equipment specific context data stored at the cluster node based on the received information.

The method may further comprise: receiving, from the second node, information indicating the layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment.

The method may further comprise: binding the layer 2 address of the user equipment to an outgoing port of the cluster node or a signalling path or network information or to the second node.

According to an aspect, there is provided a method performed at a first node of a cluster comprising the first node providing a first cell, a second node providing a second cell, and a cluster node, the method comprising: sending, to a user equipment, a cluster identifier for the cluster; and receiving, from the user equipment, a connection establishment request indicating a cluster connection request; or receiving, from the user equipment, a handover request indicating handover into the cluster.

The method may further comprise: based on the connection establishment request, establishing a connection to user equipment; determining a layer 2 address of the user equipment; and sending, to at least the cluster node and the second node, information indicating the layer 2 address of the user equipment.

The method may further comprise: sending, to the user equipment, the user equipment's cluster identifier of the user equipment as part of a connection establishment with the user equipment.

The method may further comprise: sending, to the user equipment, a destination layer 2 address to provide in uplink user plane packets sent by the user equipment to the cluster.

The layer 2 address may comprise a medium access control address.

The method may further comprise: determining a change in user equipment specific context data; and sending, to the cluster node, information indicating the change in user equipment specific context data.

The method may further comprise: receiving, from the user equipment, a protocol data unit session request comprising information indicating a support of internet protocol with layer 2 transport; sending, to the cluster node, the protocol data unit session request comprising the information indicating the support of internet protocol with layer 2 transport; receiving, from the cluster node, a response indicating that the requested protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established; and sending, to the user equipment, the response indicating that the requested protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established.

According to an aspect, there is provided a method performed at a second node of a cluster comprising a first node providing a first cell, the second node providing a second cell, and a cluster node, the method comprising: receiving, from the cluster node, user equipment specific context data associated with the user equipment's cluster identifier for the user equipment; receiving, from the user equipment, signalling messages when the user equipment is in the coverage area of the second cell, wherein the signalling comprises the user equipment's cluster identifier for the user equipment and a layer 2 address of the user equipment; determining the user equipment specific context data based on the user equipment specific context data received from the cluster node and the user equipment's cluster identifier of the user equipment received from the user equipment; and establishing a connection to the user equipment based on the determined user equipment specific context data.

The method may further comprise: determining that the user equipment has connected to the second node; determining the layer 2 address of the user equipment; sending, to at least the cluster node and the first node, information indicating the layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment; and omitting tunnel switching between the first node and the second node due to handover.

The method may further comprise: after establishing the connection to the user equipment, sending, to at least the cluster node and the first node, information indicating a change in layer 2 address of the user equipment.

The method may further comprise: receiving, from the user equipment, one or more uplink data packets comprising a destination address of a target user plane function; and sending, to the cluster node, the one or more uplink data packets comprising the destination address of the target user plane function and information indicating a layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment.

According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by a user equipment, cause the user equipment to perform at least the following: receiving, from a first node providing a first cell, a cluster identifier for a cluster comprising the first node providing the first cell, a second node providing a second cell, and a cluster node; and sending a connection establishment request to the first node or via the first node to the cluster node indicating a cluster connection request; or sending a handover request to the first node upon mobility into the first cell; or storing the cluster identifier for subsequent use when camping in a cell within the cluster.

The instructions, when executed by the user equipment, may cause the user equipment to further perform: determining that the user equipment has entered the coverage area of the cluster based on receiving the cluster identifier; and in response to the determining: sending the connection establishment request to the first node or via the first node to the cluster node indicating the cluster connection request; or sending the handover request to the first node.

The instructions, when executed by the user equipment, may cause the user equipment to further perform: receiving, from the first node or from the cluster node, the user equipment's cluster identifier of the user equipment as part of a connection establishment initiated by the first node or cluster node for a hand-over towards the cluster.

The instructions, when executed by the user equipment, may cause the user equipment to further perform: receiving, from the first node or from the cluster node, the user equipment's cluster identifier of the user equipment as part of a connection establishment with the first node or with the cluster node.

The instructions, when executed by the user equipment, may cause the user equipment to further perform: receiving, from the first node, a destination layer 2 address to provide in uplink user plane packets sent by the user equipment to the cluster.

The layer 2 address may comprise a medium access control address.

The instructions, when executed by the user equipment, may cause the user equipment to further perform: sending, to a session management function via the first node, a protocol data unit session request comprising information indicating a support of internet protocol with layer 2 transport; and receiving, from the session management function via the first node, a response indicating that a protocol data unit session providing internet protocol connectivity has been established with usage of layer 2 transport within the cluster.

The instructions, when executed by the user equipment, may cause the user equipment to further perform: determining that the user equipment has entered the coverage area of the second cell; and in response to determining that the user equipment has entered the coverage area of the second cell, executing signalling with the first node and second node to establish a connection to the second node and terminating the connection with the first node, wherein the signalling comprises the user equipment's cluster identifier of the user equipment or a layer 2 address of the user equipment.

Executing the signalling may comprise executing the signalling with the first node and the second node and the cluster node to establish the connection to the second node and terminating the connection with the first node, wherein the signalling may comprise the the user equipment's cluster identifier of the user equipment or a layer 2 address of the user equipment.

The instructions, when executed by the user equipment, may cause the user equipment to further perform: sending, via the second node, one or more uplink data packets including a layer 2 address of the user equipment and/or receiving, via the second node, one or more downlink data packets.

The instructions, when executed by the user equipment, may cause the user equipment to further perform: receiving the destination address of the target user plane function via a control plane, for example non-access stratum signalling or radio resource control signalling, or via a user plane procedure.

According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by a cluster node of a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node, cause the cluster node to perform at least the following: receiving, from the first or second node, one or more uplink data packets comprising a destination address of a target user plane function and information indicating a layer 2 address of a user equipment; determining that the layer 2 address of the user equipment is served by one of the first or second node which is reachable via a transmission link over which said one or more uplink data packets have been received; and storing an association between the layer 2 address of the user equipment and the transmission link.

The instructions, when executed by the cluster node, may cause the cluster node to further perform: receiving one or more downlink data packets addressed to the user equipment; based on the information indicating the layer 2 address of the user equipment and on the stored transmission link associated with the layer 2 address of the user equipment, determining the transmission link on which to send downlink data packets addressed to the user equipment; and sending the received one or more downlink data packets on the determined link.

The instructions, when executed by the cluster node, may cause the cluster node to further perform: sending, to the target user plane function and based on the destination address, the one or more uplink data packets.

According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by a cluster node of a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node, cause the cluster node to perform at least the following: receiving, from a user equipment via the first cell, a connection request for a user equipment; based on the user equipment connection request, sending, to the user equipment via the first node, a connection response comprising the user equipment's cluster identifier for the user equipment; and generating user equipment specific context data comprising the user equipment's cluster identifier for the user equipment.

The instructions, when executed by the cluster node, may cause the cluster node to further perform: sending, to the first node and the second node, the user equipment specific context data.

The instructions, when executed by the cluster node, may cause the cluster node to further perform: receiving, from the user equipment via the first node, a protocol data unit session request for the user equipment, the request comprising information indicating a support of internet protocol with layer 2 transport; based on the protocol data unit session request, establishing a protocol data session providing internet protocol connectivity with usage of layer 2 transport within the cluster; and sending, to the user equipment via the first node, a message indicating that a protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established.

The instructions, when executed by the cluster node, may cause the cluster node to further perform: receiving, from the first node, a request for user equipment specific context data; and in response to receiving the request for the user equipment specific context data, sending, to the first node, the generated user equipment context data.

The instructions, when executed by the cluster node, may cause the cluster node to further perform: receiving, from the first node or the second node, information indicating a change in the user equipment specific context data; and updating the user equipment specific context data stored at the cluster node based on the received information.

The instructions, when executed by the cluster node, may cause the cluster node to further perform: receiving, from the second node, information indicating the layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment.

The instructions, when executed by the cluster node, may cause the cluster node to further perform: binding the layer 2 address of the user equipment to an outgoing port of the cluster node or a signalling path or network information or to the second node.

According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by a first node of a cluster comprising the first node providing a first cell, a second node providing a second cell, and a cluster node, cause the first node to perform at least the following: sending, to a user equipment, a cluster identifier for the cluster; and receiving, from the user equipment, a connection establishment request indicating a cluster connection request; or receiving, from the user equipment, a handover request indicating handover into the cluster.

The instructions, when executed by the first node, may cause the first node to further perform: based on the connection establishment request, establishing a connection to user equipment; determining a layer 2 address of the user equipment; and sending, to at least the cluster node and the second node, information indicating the layer 2 address of the user equipment.

The instructions, when executed by the first node, may cause the first node to further perform: sending, to the user equipment, the user equipment's cluster identifier of the user equipment as part of a connection establishment with the user equipment.

The instructions, when executed by the first node, may cause the first node to further perform: sending, to the user equipment, a destination layer 2 address to provide in uplink user plane packets sent by the user equipment to the cluster.

The layer 2 address may comprise a medium access control address.

The instructions, when executed by the first node, may cause the first node to further perform: determining a change in user equipment specific context data; and sending, to the cluster node, information indicating the change in user equipment specific context data.

The instructions, when executed by the first node, may cause the first node to further perform sending the information indicating the change in user equipment specific context data to the second node.

The instructions, when executed by the first node, may cause the first node to further perform: receiving, from the user equipment, a protocol data unit session request comprising information indicating a support of internet protocol with layer 2 transport; sending, to the cluster node, the protocol data unit session request comprising the information indicating the support of internet protocol with layer 2 transport; receiving, from the cluster node, a response indicating that the requested protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established; and sending, to the user equipment, the response indicating that the requested protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established.

According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by a second node of a cluster comprising a first node providing a first cell, the second node providing a second cell, and a cluster node, cause the second node to perform at least the following: receiving, from the cluster node, user equipment specific context data associated with a user equipment's cluster identifier for the user equipment; receiving, from the user equipment, signalling messages when the user equipment is in the coverage area of the second cell, wherein the signalling comprises the user equipment's cluster identifier for the user equipment and a layer 2 address of the user equipment; determining the user equipment specific context data based on the user equipment specific context data received from the cluster node and the user equipment's cluster identifier of the user equipment received from the user equipment; and establishing a connection to the user equipment based on the determined user equipment specific context data.

The instructions, when executed by the second node, may cause the second node to further perform: determining that the user equipment has connected to the second node; determining the layer 2 address of the user equipment; sending, to at least the cluster node and the first node, information indicating the layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment; and omitting tunnel switching between the first node and the second node due to handover.

The instructions, when executed by the second node, may cause the second node to further perform: determining a change in user equipment specific context data; and sending, to the cluster node, information indicating the change in user equipment specific context data.

The instructions, when executed by the second node, may cause the second node to further perform: after establishing the connection to the user equipment, sending, to at least the cluster node and the first node, information indicating a change in layer 2 address of the user equipment.

The instructions, when executed by the second node, may cause the second node to further perform: receiving, from the user equipment, one or more uplink data packets comprising a destination address of a target user plane function; and sending, to the cluster node, the one or more uplink data packets comprising the destination address of the target user plane function and information indicating a layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment.

According to an aspect, there is provided a non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the method according to any of the preceding aspects.

In examples of any of the abovementioned aspects, the cluster node may comprises one of: radio central unit; a user plane function; and a combined central unit and user plane function.

In examples of any of the abovementioned aspects, the first cell and second cell may be small cells.

In examples of any of the abovementioned aspects, the first node and/or second node may comprise a radio unit and a radio distributed unit or a radio access point.

In the above, many different embodiments have been described. It should be appreciated that further embodiments may be provided by the combination of any two or more of the embodiments described above.

DESCRIPTION OF FIGURES

Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which: Figure 1 shows a representation of a network system according to some examples; Figure 2 shows a representation of a control apparatus according to some examples; Figure 3 shows a representation of an apparatus according to some examples; Figure 4 shows methods according to some examples; Figure 5 shows an example cluster configuration; and Figures 6 to 9 show signalling exchanges according to some examples.

DETAILED DESCRIPTION

A non-exhaustive list of some abbreviations used throughout the present disclosure is provided below for reference: 3GPP 31d Generation Partnership Program 5G 51h Generation 5GC 5G Core Network 5G-RAN 5G Radio Access Network 5GS 5G System 6G 61h Generation AMF Access and Mobility management Function AP Access Point CU Central Unit CU-CP Central Unit Control Plane CU-UP Central Unit User Plane DC Dual-Connectivity DL Downlink DNN Data Network Name DRB Data Radio Bearer DU Distributed Unit ePDG evolved Packet Data Gateway HO Handover HSS Home Subscriber Server IMSI International Mobile Subscriber Identity L2/3 Layer 2/3 LAN Local Area Network MAC Medium Access Control MC Multi-connectivity MP-QUIC Multipath QUIC MP-TCP Multipath TCP N3IWF Non-3GPP Interworking Function NAS Non-access stratum NEF Network Exposure Function NF Network Function NGAP Next Generation Application Part NG-RAN Next Generation Radio Access Network NR New Radio PDCP Packet Data Convergence Protocol PDU Packet Data Unit PSA PDU Session Anchor QoS Quality of Service RLC Radio Link Control RRC Radio Resource Control RU Radio Unit SMF Session Management Function TA Tracking Area TAC Tracking Area Code TNGF Trusted Non-3GPP Gateway Function UDM Unified Data Management UE User Equipment UL Uplink UP User Plane UPF User Plane Function In the following certain embodiments are explained with reference to mobile communication devices capable of communication via a wireless cellular system and mobile communication systems serving such mobile communication devices. Before explaining in detail, the exemplifying embodiments, certain general principles of a wireless communication system, access systems thereof, and mobile communication devices are briefly explained with reference to Figures 1, 2 and 3 to assist in understanding the technology underlying the described examples.

Figure 1 shows a schematic representation of a 5G system (5GS). The 5GS may be comprised by a terminal or user equipment (UE), a 5G radio access network (5GRAN) or next generation radio access network (NG-RAN), a 5G core network (5GC), one or more application function (AF) and one or more data networks (DN).

The 5G-RAN may comprise one or more gNodeB (GNB) or one or more gNodeB (GNB) distributed unit functions connected to one or more gNodeB (GNB) centralized unit functions.

The 5GC may comprise the following entities: Network Slice Selection Function (NSSF); Network Exposure Function (NEF); Network Repository Function (NRF); Policy Control Function (PCF); Unified Data Management (UDM); Application Function (An; Authentication Server Function (AUSF); an Access and Mobility Management Function (AMF); and Session Management Function (SMF). Figure 1 also shows the various interfaces (N1, N2 etc.) that may be implemented between the various elements of the system.

Figure 2 illustrates an example of a control apparatus 200 for controlling a function of the 5GRAN or the 5GC as illustrated on Figure 1. The control apparatus may comprise at least one random access memory (RAM) 211a, at least on read only memory (ROM) 211b, at least one processor 212, 213 and an input/output interface 214. The at least one processor 212, 213 may be coupled to the RAM 211a and the ROM 211b. The at least one processor 212, 213 may be configured to execute an appropriate software code 215. The software code 215 may for example allow to perform one or more steps to perform one or more of the present aspects. The software code 215 may be stored in the ROM 211b. The control apparatus 200 may be interconnected with another control apparatus 200 controlling another function of the 5GRAN or the 5GC. In some embodiments, each function of the 5GRAN or the 5GC comprises a control apparatus 200. In alternative embodiments, two or more functions of the 5GRAN or the 5GC may share a control apparatus.

Figure 3 illustrates an example of a terminal 300, such as the terminal illustrated on Figure 1.

The terminal 300 may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a user equipment, 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), a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, an Internet of things (loT) type communication device or any combinations of these or the like. The terminal 300 may provide, for example, communication of data for carrying communications. The communications may be one or more of voice, electronic mail (email), text message, multimedia, data, machine data and so on.

The terminal 300 may receive signals over an air or radio interface 307 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 3 transceiver apparatus is designated schematically by block 306. The transceiver apparatus 306 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

The terminal 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b and other possible components 303 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 at least one processor 301 is coupled to the RAM 302b and the ROM 302a. The at least one processor 301 may be configured to execute an appropriate software code 308. The software code 308 may for example allow to perform one or more of the present aspects. The software code 308 may be stored in the ROM 302a.

The processor, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 304. The device may optionally have a user interface such as keypad 305, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided depending on the type of the device.

Some cellular radio technologies, such as 5G or with the next-generation cellular radio technologies (6G), frequency bands beyond 100GHz and even expanding to terahertz frequencies are considered. As a result, the cell size and ISD (inter-site distance) may begin to decrease. Cell radius of only 10's of meters or less (in maximum around 100m) may be possible,. Line-of-sight (LOS) may be one of the only feasible ways for sender and receiver to communicate. In addition, the next gen cellular radio technology may be deployable in low bands to allow wide area coverage retaining the benefits of traditional cellular network. It should be understood that examples of the present disclosure may apply to other constellations or configurations and are not necessarily limited to small cells using terahertz bands.

Another possible future use case is the deployment of private networks based on 5G or 6G radio technology where 5G/6G replaces or is an add-on access technology to Wi-Fi or fixed access, which may involve integrating cellular access technologies as smoothly as possible into existing Local Area Network (LAN) infrastructure, re-using e.g., L2 switching technologies or simple bridging as much as possible.

Several possible solutions to cope with some of the problems mentioned above can be considered. These include: 1. Using dual-connectivity (DC) or multi-connectivity (MC) at PDCP layer with low bands. This may require extra signalling between master and secondary node and may lead to change of PDCP in case of mobility. It may also require availability of a low band coverage layer, which in general may not be assumed, particularly with high frequency deployments.

2. Higher layer techniques allowing for multi-connectivity like MP-TCP, MP-QUIC.

Path/link measurements may be necessary with this approach and may lead to excessive signalling and possible ping-pong effects (jumping from one path to another and back). Performance of these higher layer solutions may not be sufficient to allow for seamless handover in case of voice calls or URLLC services.

3. Pure application layer solutions, e.g., application uses different connections over different paths to send/receive data. This may not be suitable for URLLC services due to performance issues.

4. Wi-Fi networks may be considered as an untrusted network by the 3GPP system, and thus interworking between Wi-Fi and 3GPP network may be performed via ePDG/N3IWF architecture. This may have disadvantages with respect to QoS and mobility support -e.g., no guaranteed QoS in the underlay (non-3GPP) network, also no seamless mobility supported with full data integrity. This approach may be limited to basic data connectivity and basic level of service continuity and may create deployment overhead.

Providing full mobility to devices (UE) using small cells radio connectivity may lead to an increased number of signalling messages (both over the air and network internal signalling like path switch signalling) to accomplish idle mode mobility and especially connected mode handover between the small cells, each or several of the small cells being served by a small base station or Access Point (AP).

It should be understood that different configurations may be possible, e.g., an all-in-one solution where radio unit (RU) and baseband unit are collocated or where a central unit (CU) is controlling several distributed units (DU), which may be collocated with the radio unit or separated via a fronthaul interface. As used herein, a "radio access point" refers to a configuration where RU and DU or RU, DU and CU are collocated.

Changes to the network architecture and mobility procedures may be beneficial to avoid excessive signalling between UE and network (radio and core, e.g., RRC and NAS types of signalling) and within the network (e.g. in 5G terminology from RAN to AMF, AMF to UDM), when the UE changes between small cells either in idle or connected mode (which may be more likely considering the size of the small cells decreasing to the order of 10's of meters).

The network architecture and mobility procedures may also provide the means to offer integration with the macro network and the ability to support service continuity.

In short, in the area of clusters of small cells or in a LAN-type environment such as deployed in factories or on a campus, it may be important to emulate the simplicity and signalling efficiency of a Wi-Fi network but at the same time support seamless mobility offered by cellular technology. Currently W-Fi networks can be integrated with the 5G System (or EPS) as untrusted non-3GPP access using an entity called N3IWF (or ePDG) in order to connect to the 3GPP core network. This model has some limitations with respect to mobility, QoS etc. Furthermore, a cluster with small cells may be trusted, thus it may not be required to consider it as untrusted access, thus using ePDG or N3IWF for untrusted access may not be suitable. Integration of W-Fi networks as trusted non-3GPP access networks into the 5GC may also be possible but may require deployment of a TNGF to enable connectivity to the 5GC network functions, which may present barriers to implementation due to higher complexity and cost due to the usage of IPSec between the UE and the TNGF.

Some examples provide an architecture that enables light weight connectivity and switching of user plane (UP) traffic within a cluster of radio nodes. Some examples may also allow mobility with the macro network if required. Some examples may leverage the lightweight connectivity model (similar to what is offered by Wi-Fi) for densified deployments and at the same time leverage the benefit of cellular networks with seamless mobility.

Reference is made to Figure 4, which shows methods according to some examples.

At 400, a method comprises receiving, from a first node providing a first cell, a cluster identifier for a cluster comprising the first node providing the first cell, a second node providing a second cell, and a cluster node.

At 402a, the method comprises sending a connection establishment request to the first node or via the first node to the cluster node indicating a cluster connection request; or at 402b the method comprises sending a handover request to the first node upon mobility into the first cell; or at 402c the method comprises storing the cluster identifier for subsequent use when camping in a cell within the cluster.

In some examples the method of steps 400, and 402a-c may be performed at a user equipment.

At 404, a method comprises receiving, from a first or second node, one or more uplink data packets comprising a destination address of a target user plane function and information indicating a layer 2 address of a user equipment.

At 406, the method comprises determining that the layer 2 address of the user equipment is served by one of the first or second node which is reachable via a transmission link over which said one or more uplink data packets have been received.

At 408, the method comprises storing an association between the layer 2 address of the user equipment and the transmission link.

In some examples, the method of steps 404-408 may be performed at a cluster node of a cluster comprising a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node.

At 410, a method comprises receiving, from a user equipment via the first cell, a connection request for a user equipment.

At 412, the method comprises, based on the user equipment connection request, sending, to the user equipment via the first node, a connection response comprising the user equipment's cluster identifier for the user equipment.

At 414, the method comprises generating user equipment specific context data comprising the user equipment's cluster identifier for the user equipment.

In some examples, the method of steps 410-414 may be performed at a cluster node of a cluster comprising a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node.

At 416, a method comprises sending, to a user equipment, a cluster identifier for a cluster.

At 418a, the method comprises receiving, from the user equipment, a connection establishment request indicating a cluster connection request; or at 418b the method comprises receiving, from the user equipment, a handover request indicating handover into the cluster.

In some examples, the method of steps 416, 418a and 418b may be performed at a first node of a cluster comprising a cluster comprising the first node providing a first cell, a second node providing a second cell, and a cluster node.

At 420, a method comprises receiving, from a cluster node, user equipment specific context data associated with the user equipment's cluster identifier for a user equipment.

At 422, the method comprises receiving, from the user equipment, signalling messages when the user equipment is in the coverage area of the second cell, wherein the signalling comprises the user equipment's cluster identifier and a layer 2 address of the user equipment.

At 424, the method comprises determining the user equipment specific context data based on the user equipment specific context data received from the cluster node and the user equipment's cluster identifier of the user equipment received from the user equipment.

At 426, the method comprises establishing a connection to the user equipment based on the determined user equipment specific context data.

In some examples, the method of steps 420-426 may be performed at a second node of a cluster comprising a cluster comprising a first node providing a first cell, the second node providing a second cell, and a cluster node.

In some examples, cells may be combined to a logical radio cluster. Figure 5 illustrates an example cluster configuration comprising a plurality of clusters 500a-c and a UPF 502, which may be referred to herein as a cluster UPF. In some examples the cluster node can be combined with the UPF. The cluster node may in some examples provide L2 switching inside the cluster and L3 routing outside the cluster.

Each cluster may comprise one or more cluster nodes and one or more other nodes (e.g., access points) controlled by the one or more cluster nodes. For example, with reference to Figure 5, CU 506 may act as a cluster node for DUs 504a-c in cluster 500a. In cluster 500b, the cluster UPF 502 may act as a cluster node for gNBs 508a-c. In some examples the cluster node may comprise a combined UPF and CU-UP.

In some examples, as illustrated for cluster 500a, the cluster may comprise one or more DU nodes 504a-c which are connected to one or more central CU nodes 506. In such cases neither explicit RRC nor N2 signalling (between RAN and Core) may be needed in case of UE mobility within the cluster (e.g., from DU 504a to DU 504b).

In some examples, as illustrated for cluster 500b, the cluster may comprise one or more gNBs 508a-c, which contain a radio unit and baseband part (e.g., as per a classical distributed RAN configuration). In such cases, for mobility within the cluster, RRC signalling may not be needed but N2 signalling may be needed depending on the capability of the UPF (if the UPF supports the capability to detect UE mobility based on the inspection of the source MAC address of the frames it receives, N2 signalling is not needed).

In some examples, each cluster may be served by one or more CU-UP functions, as illustrated by CU-UP 510. In some examples the CU-UP may be connected to one or more dUs, as illustrated by DUs 512a-c.

In some examples, the CU-UP functions(s) may terminate PDCP and be capable of detecting UE mobility based on the reception of UL traffic from the UE. Detection of UE mobility may happen in the CU-UP, for example by inspecting the source MAC address (e.g., a DU address) where a packet is originated from. To simplify the deployment of the solution (making it a radio only solution) the CU-UP may in some examples be distinct from the UPF as this may avoid any changes to existing UPF deployments.

In some examples the cluster node(s) may control the cluster and may comprise CU (central unit) functionality (e.g., containing RRC and PDCP). The access points may provide radio unit (RU) and DU functions (up to RLC layer). The access points (RU+DU) may store UE context data in the cluster node and request UE identifier assignment from the cluster node.

In some examples, the CU functionality may be distributed to the DU(s). That is to say, in some examples the access point may comprise CU+DU+RU functionality. A combined CU+DU+RU functionality may also be referred to as a gNodeB. This may lead to some drawbacks with regards to mobility and increased signalling, for example depending on the used frequency bands.

In some examples, the DUs or access points may register at the cluster node when configured in a cluster. In this way the cluster node may be aware of the access points that are part of its cluster.

In some examples the size of the cluster can vary, for example based on different conditions, and may or may not vary dynamically -that is to say the cluster can grow or shrink.

In some examples the cluster may be defined by a certain serving area, which may be identified either by a cluster ID within a TA (Tracking Area) or identified by a single TAC (TA code). The TAC may be defined in a special way so that the UE can identify the TA as a cluster. The UE may take the TAC and/or cluster ID into account for cell (re-)selection. . The UE may take the TAC and/or cluster ID into account for the way mobility between cells takes place. Furthermore, the UE may take TAC and/or cluster ID into consideration to determine when to perform RAN notification in case of RRC_INACTIVE mode and Registration Area update.

In some examples when the cluster is identified by a cluster ID, the access point (DU) may broadcast the cluster ID allowing the UE to recognize when it is moving in and out of the cluster. The cluster ID can be unique for a given cluster. In some implementations, a UE's cluster identifier of the user equipment may be allocated to identify the UE and provided to the UE -for example assigning a UE's cluster identifier of the user equipment in a unique way per UE. . When the UE is moving in or out of the cluster, cell (re-)selection principles and HO procedures, such as those defined by R18 3GPP TS 23.502, TS 38.331 or 38.300, may apply.

While inside the cluster, the UE may provide measurement data to the access points and/or cluster node, but no explicit HO signalling may be sent as all access nodes (e.g., DU+RU, access point or gNodeB) can receive user plane traffic from and for all UE(s) camping within the cluster. Signalling between UE and cluster nodes may be exchanged to establish radio bearers for subsequent exchanges of signalling and user plane traffic. Cell (re-)selection principles within the UE may be updated to use the cluster ID (if available) in addition to the TAC for deciding which cell to select.

Thus, in some examples a UE can move inside the cluster and send/receive data while minimizing the control and user plane related signalling between UE and network, also minimize signalling overhead within the network as a result to UE mobility between cells of a cluster.

Some examples may enable L2 mobility within a cluster of radio nodes along with support for L3 mobility between clusters and/or L3 mobility between clusters and the macro network. Some examples may enable both the UE and the network (e.g., CU-UP or UPF at the edge of the cluster) to support both L2/L3 based networking for a given session (e.g., L2 switching inside the cluster and L3 routing outside). In this way, some examples may enable light weight connectivity and simplified HO when the UE moves within the cluster and may enable seamless mobility between the cluster and the macro network.

As used herein, L3 mobility may refer to existing Handover RRC signalling between UE and network and N2 signalling between RAN and Core while preserving the UE's IP address (which in some examples may be allocated by a PSA UPF which may be the same as the cluster UPF or a separated entity); L2 mobility may refer to cluster nodes using MAC address learning techniques such as in ethernet based networking to associate the UE's MAC (or L2) address with a specific outgoing port; and L2-L3 mobility may refer to the ability to support interworking between L2 switching and L3 HO for a given session.

Reference is made to Figure 6, which shows a signalling exchange according to some examples.

In the example of Figure 6, a cluster comprises a cluster node (e.g., UPF+CU), a first cell provided by a first node and a second cell provided by a second node. The cluster may be served by one or more cluster UPFs. For a given UE, there may be one cluster UPF assigned which serves the UE. The first node and second node may for example comprise dUs and the cluster node may comprise a CU. The cluster node can comprise a UPF.

At 600, when UE enters the first cell, the UE may receive, from the first node, a tracking area code (TAC) and a cluster indicator and/or cluster ID. In response to receiving the TAC and/or cluster ID, the UE may determine that it has entered the coverage area of the cluster. The cluster ID may be received from the first node as broadcast information or in dedicated signalling. The cluster ID may correspond to a different information than a tracking area code (TAC) or may correspond to a tracking area code (TAC) together with an indication that the tracking area corresponds to a cluster.

At 602, the UE may establish a connection with the first node. The UE may for example establish the connection in response to receiving the TAC and/or cluster identifier. The establishing may include indicating a cluster connection request when requesting the connection. As part of the connection establishment (or later in step 606 when receiving a connection response, the UE may receive, from the first node, a destination layer 2 address to provide in uplink user plane packets sent by the user equipment to the cluster.

In some examples, as part of the connection establishment, the UE may send, to the first node, information indicating a layer 2 address of the user equipment. The first node may send the information indicating a layer 2 address of the user equipment to the other nodes in the cluster -for example the cluster node and second node.

In some examples, as part of the connection establishment, the UE may send a layer 2 address to the other nodes in the cluster.

In some examples, the connection establishment may be initiated by the UE, as shown in Figure 6. In other examples, the connection establishment may be initiated by a handover of the UE from a cell outside the cluster. In the latter case (handover of the UE from a cell outside the cluster) step 604/606 may not apply and the UE may receive the UE's cluster identifier for UE as part of the L3 handover procedure In some examples when the UE is entering the cluster for the first time, the UE may connect to the cluster which depending on whether the UE is entering the cluster in IDLE mode or in CONNECTED mode (via a L3 Handover) may correspond to an explicit RRC connection request from the UE (the UE is entering the cluster in IDLE mode) or to a Hand-over related signalling. For example, the UE may perform an RRC procedure with the CU or any unit providing RRC functionality that may trigger UE specific cluster identifier assignment and/or other procedures resulting in UE connect to the cluster.

For example, at 604, after establishing the connection, the UE may send a connection request to the cluster node via the first node. The connection request may comprise a unique layer 2 address of the user equipment.

In some examples, the UE may follow an initial access procedure as defined in 3GPP TS 38.401. However, it should be understood that examples of the present disclosure are not limited to such an access procedure, and that other procedures for initial UE access are considered within the scope of the present disclosure.

As part of the initial UE access, the cluster node may ensure that the UE has been authenticated once it enters the cluster. Thereafter the UE may be "trusted" and may be allowed to move across access points within the cluster, for example using L2 techniques. This will be discussed in more detail below with reference to Figure 7.

At 606, the UE may receive a connection response from the cluster node via the first node.

The connection response may comprise a UE's cluster identifier for the user equipment.

In some examples the connection response may further comprise information indicating support for certain capabilities provided by the cluster node (e.g., emergency services support), and/or UE specific feature capability (e.g., DRB ID and other parameters, such as SRB information, etc.).

In some examples the cluster node may generate and/or allocate the user equipment's cluster identifier during first connection establishment. Otherwise, the access point (e.g., first node) may request the user equipment's cluster identifier for the user equipment from the cluster node via extra signalling. In some examples the user equipment's cluster identifier for the user equipment may be allocated by the respective access point from a pool and distributed to all other access points or stored centrally in the cluster node and distributed by the cluster node to all other nodes in the cluster.

In some examples the user equipment's cluster identifier for the user equipment may be a L3 (e.g., IP address) or L2 (e.g., MAC ID) derived identifier. In some examples the cluster node may ensure that the identifier is not predictable to ensure privacy and subscriber confidentiality. The identifier may be renewed periodically to avoid being traced back to a certain UE.

At 608, after successful UE registration, the cluster node may generate UE specific context data (e.g., UE identifiers, security keys, radio bearers, timers, etc.) and at 610 send the UE specific context data to other nodes (e.g., DUs/gNBs) in the cluster. In some examples the UE context data may include the user equipment's cluster identifier. The UE context data may also include one or more UE specific keys. The UE context data may be updated periodically, if necessary.

For example, as shown in Figure 6, the cluster node may send the UE specific context data to the first and second nodes. The UE specific context data may comprise or otherwise be associated with the user equipment's cluster identifier.

In other examples the UE context data may be stored centrally in the cluster node or a database where the context data can be requested by the access points. Access to the context data can be provided based on the user equipment's cluster identifier.

In some examples, when the serving node determines that UE context data changes, the serving node may inform the cluster node, and optionally the other nodes, of the change in UE context data.

In some examples when the UE is leaving the cluster, the cluster node may remove UE context data in the access points and the central data base. In some examples the removal may be performed after the UE has left the cluster and a period of time has expired after the UE has left the cluster.

In some examples, to ensure privacy and confidentiality, the cluster node and access point may maintain a per UE association, and the cluster node may encrypt UE specific parts of the identifier using a key it receives during UE registration. In some examples only the part addressing the UE or the UE association in the access point may be used for packet forwarding. The access point may receive a DL packet and forward it to the corresponding data radio bearer.

At 612 the UE may establish a PDU session with the network. An example of establishing the PDU session is described below with reference to Figure 9.

Reference is made to Figure 8, which shows a signalling exchange according to some examples.

In the example of Figure 8, a cluster comprises a cluster node (e.g., UPF+CU), a first cell provided by a first node and a second cell provided by a second node. The cluster may be served by one or more cluster UPFs. For a given UE, there may be one cluster UPF assigned which serves the UE. The first node and second node may for example comprise of an access node (e.g., gNodeB) providing combined CU+DU functionality. The cluster node can comprise a UPF.

At 800, when UE enters the first cell, the UE may receive, from the first node, a tracking area code (TAC) and a cluster indicator and/or cluster ID. In response to receiving the TAO and/or cluster ID, the UE may determine that it has entered the coverage area of the cluster. The cluster ID may be received from the first node as broadcast information or in dedicated signalling. The cluster ID may correspond to a different information than a tracking area code (TAC)or may correspond to a tracking area code (TAC) together with an indication that the tracking area corresponds to a cluster.

At 802, the UE may establish a connection with the first node. The UE may for example establish the connection in response to receiving the TAO and cluster indicator and/or cluster identifier. The establishing may include indicating a cluster connection request when requesting the connection. As part of the connection establishment (or later in step 806 when receiving a connection response, the UE may receive, from the first node, a destination layer 2 address to provide in uplink user plane packets sent by the user equipment to the cluster.

In some examples, the connection establishment may be initiated by the UE, as shown in steps 804/806 of Figure 8. In other examples, the connection establishment may be initiated by a handover of the UE from a cell outside the cluster. In the latter case (handover of the UE from a cell outside the cluster) steps 804/806 may not apply and the UE may receive the UE's cluster identifier for UE as part of the L3 handover procedure In some examples when the UE is entering the cluster for the first time, the UE may connect to the cluster which depending on whether the UE is entering the cluster in IDLE mode or in CONNECTED mode (via a L3 Handover) may correspond to an explicit RRC connection request from the UE (e.g., the UE is entering the cluster in IDLE mode) or to a Hand-over related signalling. For example, the UE may perform an RRC procedure with the CU or any unit providing RRC functionality that may trigger, UE specific UE's cluster identifier assignment and/or other procedures resulting in UE connect to the cluster.

For example, at 804, after establishing the connection, the UE may send a connection request to the first node. The connection request may comprise a unique layer 2 address of the user equipment.

As part of the initial UE access, the first node may ensure that the UE has been authenticated once it enters the cluster. Thereafter the UE may be "trusted" and may be allowed to move across access points within the cluster, for example using L2 techniques. This will be discussed in more detail below with reference to Figure 7.

At 806, the UE may receive a connection response from the first node. The connection response may comprise a UE's cluster identifier for the user equipment.

In some examples the connection response may further comprise information indicating support for certain capabilities provided by the cluster (e.g., emergency services support), and/or UE specific feature capability (e.g., DRB ID and other parameters, such as SRB information, etc.).

In some examples the cluster node may generate and/or allocate the user equipment's cluster identifier during first connection establishment. Otherwise, the access point (e.g., first node) may request the user equipment's cluster identifier from the cluster node via extra signalling. In some examples the user equipment's cluster identifier may be allocated by the respective access point from a pool and distributed to all other access points or stored centrally in the cluster node and distributed by the cluster node to all other nodes in the cluster.

In some examples the user equipment's cluster identifier may be a L3 (e.g., IP address) or L2 (e.g., MAC ID) derived identifier. In some examples the cluster node may ensure that the identifier is not predictable to ensure privacy and subscriber confidentiality. The identifier may be renewed periodically to avoid being traced back to a certain UE.

At 808, after successful UE connection to the cluster, the first node may generate UE specific context data (e.g., UE identifiers, security keys, radio bearers, timers, etc.).

At 810 the UE may send information to the cluster node indicating the user equipment connection.

The cluster node may at 812 send the UE specific context data to other nodes (e.g., second node) in the cluster. In some examples the UE context data may include the user equipment's cluster identifier. The UE context data may also include one or more UE specific keys. The UE context data may be updated periodically, if necessary. The UE specific context data may comprise or otherwise be associated with the user equipment's cluster identifier.

In some examples, to ensure privacy and confidentiality, the cluster node and access point may maintain a per UE association, and the cluster node may encrypt UE specific parts of the identifier using a key it receives during UE registration. In some examples only the part addressing the UE or the UE association in the access point may be used for packet forwarding.

In some examples, as part of the initial UE access with the cluster, the UE and cluster node may exchange capability information for supporting a "hybrid" IP/L2 PDU session, enabling L2 mobility within the cluster and L3 mobility outside the cluster.

In some examples, when the UE and cluster node support the hybrid IP/L2 PDU session, the first node, second node or the UE may advertise the UE's new L2 address to the cluster node -for example via L2 mechanisms. This may allow the cluster node to forward DL packets addressed to the UE to this new cell. This may for example occur when the UE first enters the cluster, or when the UE moves within the cluster. An example of this behaviour is described below with reference to Figure 7.

At 814 the UE may establish a PDU session with the network. An example of establishing the PDU session is described below with reference to Figure 9.

Reference is made to Figure 9, which shows a signalling exchange according to some examples. The signalling exchange of Figure 9 may for example be used to establish a PDU session, such as that described above at step 612 of Figure 6 or step 814 of Figure 8.

At 900,the UE may send a PDU session request via the first node to the session management function. The PDU session request may comprise information indicating support of IP with L2 transport or IP and Ethernet (hybrid PDU Session). The PDU session request may further comprise information indicating a layer 2 address of the UE.

At 902, based on the request, the session management function may establish a PDU session in the core network and may inform the cluster node. The PDU session may be a PDU session providing IP connectivity with usage of L2 transport/Ethernet enabled within the cluster.

At 904, the session management function may send to the UE via the first node, a message indicating that a PDU session has been established, for example a message indicating that a PDU session providing IP connectivity with usage of L2 transport/Ethernet within the cluster has been established.

When the PDU session for IP with layer 2 transport/Ethernet is established, the cluster node and/or UPF may act as a L2 switch inside the cluster (e.g., may forward ethernet frames to the UE based on UE source address, e.g., MAC ID) and as a L3 router outside of the cluster (e.g., may forward packets based on destination address, e.g., IP address).

Reference is made to Figure 7, which shows a signalling exchange according to some examples. In this example, it is assumed that the UE and cluster node support the hybrid IP/L2 PDU session, such that L2 mobility within the cluster is enabled. It is further assumed that the UE has established a hybrid I P/ETH PDU session with the cluster node.

At 700, the UE may determine that the UE has moved from the first cell to the second cell e.g., from the coverage area of the first node to the coverage area of the second node. This may for example be based on one or more measurements made by the UE.

At 702, the UE executes signalling with the first node and second node (e.g., lower layer signalling) to establish a connection with the second node and disconnect from the first node. Establishing the new connection to the second node and terminating the existing connection to the first node can be triggered by the network during HO signalling or by the UE without explicit handover signalling.

As part of the signalling the UE may provide the UE's cluster identifier of the user equipment to the second node. The UE may also provide a layer 2 address of the UE. The second node may retrieve the UE specific context data associated with the UE's cluster identifier of the UE or using layer 2 address of the UE. The UE specific context data may be either locally stored at the second node when it is sent by the cluster node or may be fetched from the cluster node or a central data base when not locally available. The second node may establish the connection based on the UE specific context data.

In some examples, the first cell and the second cell may be controlled or provided by different entities -for example a first DU may cover the first cell and a second DU may cover the second cell. However, in other examples, the first cell and second cell may be covered by the same entity (e.g., the same DU). In such cases the UE may not execute the lower layer signalling at 702 when moving from the first cell to the second cell.

In some examples, when the UE is connected to the second node, the second node or the UE may advertise the UE's new L2 address (e.g., MAC ID or MAC address) to the nodes in the cluster ( e.g., at least the cluster node and the first node) -for example via an L2 mechanism. In some examples, the second node may determine that the UE context data has changed and may inform the cluster node, and optionally the nodes covering the other cells, of the change in UE context data.

Once the UE has established a signalling connection with the second node, at 704 the second node may send to the other nodes in the cluster (e.g., cluster node and first node), information indicating the layer 2 address of the user equipment. The information indicating the layer 2 address of the user equipment may comprise information indicating that the second node is serving the user equipment.

Once the UE has established a signalling connection with the second node, at 705 the UE may send to the other nodes in the cluster (e.g., cluster node and first node), information indicating the layer 2 address of the user equipment. The information indicating the layer 2 address of the user equipment may comprise information indicating that the second node is serving the user equipment. In some examples, tunnel switching between the first node and the second node due to handover is not performed.

After establishing the signalling connection, the UE may send uplink data packets or receive downlink data packets associated with the established PDU session via the second node.

For example, at 706 the UE may send uplink data packets to the second node. The uplink data packets may comprise a target UPF destination address (e.g., MAC ID or MAC address) and source address (e.g., MAC ID) of the UE.

At 708 the second node may forward the uplink data packets to the cluster node. In some examples, HO and Xn signalling between first and second node is not performed. In some examples, the Fl interface between DU and CU may use Ethernet transport instead of using GTP-U protocol which may avoid the necessity to switch the GTP-U tunnel between first DU and second DU. In some examples, tunnel switching due to handover is not performed.

In some examples, after receiving the uplink data packets, the cluster node may determine that the layer 2 address of the user equipment is served by the second node which is reachable via the transmission link over which said one or more uplink data packets have been received. The cluster node may then store an association between the layer 2 address of the UE and the transmission link.

It should be understood that the cluster node may employ a similar mechanism when receiving uplink data packets from the first node -e.g., the cluster node may determine that the layer 2 address of the user equipment is served by the first node which is reachable via the transmission link over which the one or more uplink data packets have been received. The cluster node may then store an association between the layer 2 address of the UE and the transmission link.

At 710, the cluster node may forward the uplink data packets on to a target UPF based on the destination address. That is to say, the cluster node may act as a L3 router for the uplink data packets to route the uplink data packets to the correct destination.

At 712, downlink data packets for the UE may be received at the cluster node. The downlink data packets may for example be sent by the target UPF.

At 714, the cluster node may determine a transmission link on which to send the downlink data packets. The determination may be based on the information indicating the layer 2 address of the user equipment and on the stored transmission link associated with the layer 2 address of the user equipment.

As described previously, in some examples the cluster node may determine the point of attachment of the UE (e.g., access point, such as DU/gNB) where to send frames to by using MAC learning procedures. Once the UE attaches to an access point, the access point may advertise the UE's MAC address to the cluster or specifically to the cluster node, or the UE may send a MAC frame in uplink direction which may allow the cluster node to associate the UE MAC address with the radio node address or with the next hop where to send a DL packet to. In some examples when the UE's point of attachment is not known to the cluster node or it is outdated, the cluster node can send a broadcast message to all access points within the cluster to learn to which access point the UE is currently connected to.

At 716, the cluster node sends the downlink data packets on the determined link to the determined next hop or another node -in the example of figure 7 this is the second node.

That is to say, the cluster node may act as a L2 switch for the downlink data packets to route the downlink data packets to the correct node within the cluster serving the UE.

At 718, the second node sends the downlink data packets to the UE.

In some examples, the UE and/or cluster node may not support the hybrid IP/L2 PDU session, and thus L2 mobility within the cluster is not enabled. In such cases the UE may establish a normal PDU session with the cluster node for IP connectivity.

In some examples the first node may receive, from the core network, information indicating that the first node is to operate using layer 2 transport (e.g., ethernet transport) within the cluster without UE support -e.g., the first node must rely on signalling (e.g., via Xn interface) with the second node for performing handover of the UE.

In some examples the UE may determine that the UE has moved from the first cell to the second cell -e.g., from the coverage area of the first node to the coverage area of the second node. This may for example be based on one or more measurements made by the UE.

Handover of the UE from the first node to the second node may then be performed according to existing handover mechanisms. As part of the handover, the second node may receive, from the first node, the destination address (e.g., MAC address) of the target UPF for the UE's PDU session.

In some examples, the second node may transmit a dummy packet (e.g., GTP-U packet) to the target UPF. Based on receiving the dummy packet, the target UPF may identify the second node.

In some examples the UE may send, to the second node, uplink data packets, and the second node may send, to the target UPF, the uplink data packets. The second node may further send information identifying the source address of the UE (e.g., a MAC ID) when sending the uplink data packets to the target UPF.

Based on the source address of the UE and the dummy packet, the target UPF may associate the second node with the UE -e.g., may associate the MAC ID of the UE with the GTP-U address of the second node. In this way, the target UPF may determine that the UE is being served by the second node after handover has been performed.

In some examples the target UPF may send, to the cluster UPF, downlink packets addressed to the UE. The cluster UPF may then forward the downlink packets to the nodes in the cluster -for example the first node and second node. The node serving the UE, e.g the second node, may then receive the downlink packets and send the packets to the UE.

In some examples the user plane may be anchored centrally to avoid frequent breaks in the service offering. The UE may support multi-homing to enable frequent relocation without IP anchor change and at the same time enable support of a stable IP anchor in the central UPF. Even if the UE leaves the cluster, in some examples the cluster UPF may be maintained to avoid IP address change. In other examples the cluster UPF can also change. In examples where the central UPF allocates the IP address for the UE, the change of cluster UPF may not break session continuity.

In some examples, the same or similar procedure may be usable for cluster to macro network mobility and cluster to cluster mobility. Cluster to cluster mobility (i.e., UE mobility from a source cluster to a target cluster) may be achieved by forwarding UE context data and packets between the source cluster node and target cluster node. The target cluster node may assign a new cluster identifier and security keys to the UE once it enters the target cluster.

In some examples, when the UE leaves a cluster, the UE may not receive the cluster ID in broadcast messages anymore. Thus, the UE may register in the target cell by the usual means (e.g., providing measurement reports, RRC connection establishment, registration procedure with authentication, etc., for example as set out in 3GPP TS 23.502, TS 38.331 and/or TS 38.300). HO of context data can be provided via Xn-like interface between cluster node and target base station or via AMF using NGAP protocol. After HO execution, cluster node (including CU) may remove UE context data locally and in all dUs of the given cluster.

In some examples the first node and/or second node may comprise a radio unit (RU) + radio distributed unit (DU). In some examples the first and/or second node may comprise a radio access point, such as a gNodeB (gNB) or 6G access point.

Examples have been provided whereby a cluster a cluster node and a plurality of access points are grouped into a logical radio cluster. A UE first entering the coverage area of one of the access points of the cluster may register with the cluster node, and once authorized, may freely move between access points of the cluster using L2 techniques. The cluster node may determine the L2 address of the UE, for example from the UE in uplink data packets, or from an access point when the UE establishes one connection with the access point. Uplink data packets sent by the UE may be routed based on an L3 address, e.g., IP address, while downlink data packets addressed to the UE may be routed to the serving access point based on L2 addresses, e.g., MAC ID. Some examples may therefore enable light weight connectivity and simplified HO when the UE moves within the cluster and may enable seamless mobility between clusters or between a cluster and the macro network.

In some examples, an apparatus may comprise means for performing any of the abovementioned steps.

In some examples a user equipment may comprise means for: receiving, from a first node providing a first cell, a cluster identifier for a cluster comprising the first node providing the first cell, a second node providing a second cell, and a cluster node; and sending a connection establishment request to the first node or via the first node to the cluster node indicating a cluster connection request; or sending a handover request to the first node upon mobility into the first cell; or storing the cluster identifier for subsequent use when camping in a cell within the cluster.

In some examples a cluster node (of a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node) may comprise means for: receiving, from the first or second node, one or more uplink data packets comprising a destination address of a target user plane function and information indicating a layer 2 address of a user equipment; determining that the layer 2 address of the user equipment is served by one of the first or second node which is reachable via a transmission link over which said one or more uplink data packets have been received; and storing an association between the layer 2 address of the user equipment and the transmission link.

In some examples a cluster node (of a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node) may comprise means for: receiving, from a user equipment via the first cell, a connection request for a user equipment; based on the user equipment connection request, sending, to the user equipment via the first node, a connection response comprising 'the user equipment's cluster identifier; and generating user equipment specific context data comprising the 'user equipment's cluster identifier.

In some examples a first node (of a cluster comprising the first node providing a first cell, a second node providing a second cell, and a cluster node) may comprise means for: sending, to a user equipment, a cluster identifier for the cluster; and receiving, from the user equipment, a connection establishment request indicating a cluster connection request; or receiving, from the user equipment, a handover request indicating handover into the cluster.

In some examples a second node (of a cluster comprising a first node providing a first cell, the second node providing a second cell, and a cluster node) may comprise means for: receiving, from the cluster node, user equipment specific context data associated with a UE's cluster identifier for the user equipment; receiving, from the user equipment, signalling messages when the user equipment is in the coverage area of the second cell, wherein the signalling comprises the UE's cluster identifier for the user equipment and a layer 2 address of the user equipment; determining the user equipment specific context data based on the user equipment specific context data received from the cluster node and the cluster unique identifier of the user equipment received from the user equipment; and establishing a connection to the user equipment based on the determined user equipment specific context data.

In some examples, an apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform any of the abovementioned steps.

In some examples a user equipment may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the user equipment at least to: receive, from a first node providing a first cell, a cluster identifier for a cluster comprising the first node providing the first cell, a second node providing a second cell, and a cluster node; and send a connection establishment request to the first node or via the first node to the cluster node indicating a cluster connection request; or send a handover request to the first node upon mobility into the first cell; or store the cluster identifier for subsequent use when camping in a cell within the cluster.

In some examples a cluster node (of a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node) may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the cluster node at least to: receive, from the first or second node, one or more uplink data packets comprising a destination address of a target user plane function and information indicating a layer 2 address of a user equipment; determine that the layer 2 address of the user equipment is served by one of the first or second node which is reachable via a transmission link over which said one or more uplink data packets have been received; and store an association between the layer 2 address of the user equipment and the transmission link.

In some examples a cluster node (of a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node) may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the cluster node at least to: receive, from a user equipment via the first cell, a connection request for a user equipment; based on the user equipment connection request, send, to the user equipment via the first node, a connection response comprising 'the user equipment's cluster identifier; and generate user equipment specific context data comprising the 'user equipment's cluster identifier.

In some examples a first node (of a cluster comprising the first node providing a first cell, a second node providing a second cell, and a cluster node) may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the first node at least to: send, to a user equipment, a cluster identifier for the cluster; and receive, from the user equipment, a connection establishment request indicating a cluster connection request; or receive, from the user equipment, a handover request indicating handover into the cluster.

In some examples a second node (of a cluster comprising the first node providing a first cell, the second node providing a second cell, and a cluster node) may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the first node at least to: receiving, from the cluster node, user equipment specific context data associated with the UE's cluster identifier for the user equipment; receiving, from the user equipment, signalling messages when the user equipment is in the coverage area of the second cell, wherein the signalling comprises the UE's cluster identifier for the user equipment and a layer 2 address of the user equipment; determining the user equipment specific context data based on the user equipment specific context data received from the cluster node and the UE's cluster identifier of the user equipment received from the user equipment; and establishing a connection to the user equipment based on the determined user equipment specific context data.

It is understood that references in the above to various network functions (e.g., to an AMF, an SMF, etc.) may comprise apparatus that perform at least some of the functionality associated with those network functions. Further, an apparatus comprising a network function may comprise a virtual network function instance of that network function.

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 embodiments have been described in relation to 5G networks, similar principles can be applied in relation to other networks and communication systems. Therefore, although certain embodiments were described above by way of example with reference to certain example architectures for wireless networks, technologies and standards, 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 the present invention.

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 wording, 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.

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 in this application, 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) andiii) 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 in this application, including in any claims. As a further example, as used in this application, 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 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 (i.e., 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.

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 embodiments of the disclosure is set out by the independent claims. The embodiments and features, 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 embodiments of the disclosure.

The foregoing description has provided by way of non-limiting examples a full and informative description of the exemplary embodiment 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 appended claims. However, all such and similar modifications of the teachings of this disclosure will still fall within the scope of this invention as defined in the appended claims.

Indeed, there is a further embodiment comprising a combination of one or more embodiments with any of the other embodiments previously discussed.

Claims

CLAIMS1. A method performed at a user equipment, the method comprising: receiving, from a first node providing a first cell, a cluster identifier for a cluster comprising the first node providing the first cell, a second node providing a second cell, and a cluster node; and sending a connection establishment request to the first node or via the first node to the cluster node indicating a cluster connection request; or sending a handover request to the first node upon mobility into the first cell; or storing the cluster identifier for subsequent use when camping in a cell within the cluster.
2. The method of claim 1, wherein the receiving comprises: receiving the cluster identifier as broadcast information in the first cell; or receiving at least one of the cluster identifier and the user equipment's cluster identifier in a signalling dedicated to the user equipment, wherein the cluster identifier is unique to the cluster and the user equipment's cluster identifier is unique to the user equipment.
3. The method of claim 1 or 2, further comprising: determining that the user equipment has entered the coverage area of the cluster based on receiving the cluster identifier; and in response to the determining: sending the connection establishment request to the first node or via the first node to the cluster node indicating the cluster connection request; or sending the handover request to the first node.
4. The method of any previous claim, further comprising: receiving, from the first node or from the cluster node, a user equipment's cluster identifier as part of a connection establishment initiated by the first node or cluster node for a hand-over towards the cluster.
5. The method of any previous claim, further comprising: receiving, from the first node or from the cluster node, a user equipment's cluster identifier as part of a connection establishment with the first node or with the cluster node.
6. The method of any previous claim, further comprising: receiving, from the first node, a destination layer 2 address to provide in uplink user plane packets sent by the user equipment to the cluster.
7. The method of claim 6, wherein the layer 2 address comprises a medium access control address.
8. The method of any preceding claim, further comprising: sending, to a session management function via the first node, a protocol data unit session request comprising information indicating a support of internet protocol with layer 2 transport; and receiving, from the session management function via the first node, a response indicating that a protocol data unit session providing internet protocol connectivity has been established with usage of layer 2 transport within the cluster.
9. The method of claim 8, wherein the protocol data unit session request further comprises information indicating a layer 2 address of the user equipment.
10. The method of any preceding claim, further comprising: determining that the user equipment has entered the coverage area of the second cell; and in response to determining that the user equipment has entered the coverage area of the second cell, executing signalling with the first node and second node to establish a connection to the second node and terminating the connection with the first node, wherein the signalling comprises the user equipment's cluster identifier or a layer 2 address of the user equipment.
11. The method of claim 10, wherein executing the signalling comprises executing the signalling with the first node and the second node and the cluster node to establish the connection to the second node and terminating the connection with the first node, wherein the signalling comprises the user equipment's cluster identifier or a layer 2 address of the user equipment.
12. The method of claim 11, further comprising: sending, via the second node, one or more uplink data packets including a layer 2 address of the user equipment and/or receiving, via the second node, one or more downlink data packets.
13. The method of claim 12, wherein the one or more uplink data packets further comprise a destination address of a target user plane function, or further comprises an identifier mapping to the destination address of a target user plane function.
14. The method of claim 13, further comprising: receiving the destination address of the target user plane function via a control plane, for example non-access stratum signalling or radio resource control signalling, or via a user plane procedure.
15. A method performed at a cluster node of a cluster comprising a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node, the method comprising: receiving, from the first or second node, one or more uplink data packets comprising a destination address of a target user plane function and information indicating a layer 2 address of a user equipment; determining that the layer 2 address of the user equipment is served by one of the first or second node which is reachable via a transmission link over which said one or more uplink data packets have been received; and storing an association between the layer 2 address of the user equipment and the transmission link.
16. The method of claim 15, further comprising: receiving one or more downlink data packets addressed to the user equipment; based on the information indicating the layer 2 address of the user equipment and on the stored transmission link associated with the layer 2 address of the user equipment, determining the transmission link on which to send downlink data packets addressed to the user equipment; and sending the received one or more downlink data packets on the determined link.
17. The method of claim 15 or 16, further comprising: sending, to the target user plane function and based on the destination address, the one or more uplink data packets.
18. A method performed at a cluster node of a cluster comprising a cluster comprising a first node providing a first cell, a second node providing a second cell, and the cluster node, the method comprising: receiving, from a user equipment via the first cell, a connection request for a user equipment; based on the user equipment connection request, sending, to the user equipment via the first node, a connection response comprising the user equipment's cluster identifier for the user equipment; and generating user equipment specific context data comprising the user equipment's cluster identifier for the user equipment.
19. The method of claim 18, wherein the user equipment specific context data is stored in a database accessible by at least the first node and the second node.
20. The method of claim 18, further comprising: sending, to the first node and the second node, the user equipment specific context data.
21. The method of any of claims 18 to 20, wherein the connection request comprises a unique layer 2 address of the user equipment.
22. The method of any of claims 18 to 21, further comprising: receiving, from the user equipment via the first node, a protocol data unit session request for the user equipment, the request comprising information indicating a support of internet protocol with layer 2 transport; based on the protocol data unit session request, establishing a protocol data session providing internet protocol connectivity with usage of layer 2 transport within the cluster; and sending, to the user equipment via the first node, a message indicating that a protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established.
23. The method of any of claims 18 to 22, further comprising: receiving, from the first node, a request for user equipment specific context data; and in response to receiving the request for the user equipment specific context data, sending, to the first node, the generated user equipment context data.
24. The method of any of claims 18 to 23, further comprising: receiving, from the first node or the second node, information indicating a change in the user equipment specific context data; and updating the user equipment specific context data stored at the cluster node based on the received information.
25. The method of any of claims 18 to 24, further comprising: receiving, from the second node, information indicating the layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment.
26. The method of claim 25, further comprising: binding the layer 2 address of the user equipment to an outgoing port of the cluster node or a signalling path or network information or to the second node.
27. A method performed at a first node of a cluster comprising the first node providing a first cell, a second node providing a second cell, and a cluster node, the method comprising: sending, to a user equipment, a cluster identifier for the cluster; and receiving, from the user equipment, a connection establishment request indicating a cluster connection request; or receiving, from the user equipment, a handover request indicating handover into the cluster.
28. The method of claim 27, wherein the sending comprises sending the cluster identifier as broadcast information in the first cell or in signalling dedicated to the user equipment.
29. The method of claim 27 or 28, further comprising: based on the connection establishment request, establishing a connection to user equipment; determining a layer 2 address of the user equipment; and sending, to at least the cluster node and the second node, information indicating the layer 2 address of the user equipment.
30. The method of any of claims 27 to 29, further comprising: sending, to the user equipment, a user equipment's cluster identifier as part of a connection establishment with the user equipment.
31. The method of any of claims 27 to 30, further comprising: sending, to the user equipment, a destination layer 2 address to provide in uplink user plane packets sent by the user equipment to the cluster.
32. The method of claim 31, wherein the layer 2 address comprises a medium access control address.34. The method of any of claims 29 to 32, wherein determining the layer 2 address of the user equipment comprises receiving the layer 2 address from the user equipment.35. The method of any of claims 27 to 34, further comprising: determining a change in user equipment specific context data; and sending, to the cluster node, information indicating the change in user equipment specific context data.36. The method of claim 35, wherein the sending further comprises sending the information indicating the change in user equipment specific context data to the second node.37. The method of any of claims 27 to 36, further comprising: receiving, from the user equipment, a protocol data unit session request comprising information indicating a support of internet protocol with layer 2 transport; sending, to the cluster node, the protocol data unit session request comprising the information indicating the support of internet protocol with layer 2 transport; receiving, from the cluster node, a response indicating that the requested protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established; and sending, to the user equipment, the response indicating that the requested protocol data unit session providing internet protocol connectivity with usage of layer 2 transport within the cluster has been established.38. A method performed at a second node of a cluster comprising a first node providing a first cell, the second node providing a second cell, and a cluster node, the method comprising: receiving, from the cluster node, user equipment specific context data associated with a user equipment's cluster identifier; receiving, from the user equipment, signalling messages when the user equipment is in the coverage area of the second cell, wherein the signalling comprises the user equipment's cluster identifier and a layer 2 address of the user equipment; determining the user equipment specific context data based on the user equipment specific context data received from the cluster node and the user equipment's cluster identifier received from the user equipment; and establishing a connection to the user equipment based on the determined user equipment specific context data.39. The method of claim 38, further comprising: determining that the user equipment has connected to the second node; determining the layer 2 address of the user equipment; sending, to at least the cluster node and the first node, information indicating the layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment; and omitting tunnel switching between the first node and the second node due to handover. 15 40. The method of claim 39, wherein determining that the user equipment has connected to the second node is based on signalling received from at least one of: the user equipment, the first node, the cluster node, or other network node.41. The method of any of claims 38 to 40, further comprising: determining a change in user equipment specific context data; and sending, to the cluster node, information indicating the change in user equipment specific context data.42. The method of claim 41, wherein the sending further comprises sending the information indicating the change in user equipment specific context data to the first node.43. The method of any of claims 38 to 42, further comprising: after establishing the connection to the user equipment, sending, to at least the cluster node and the first node, information indicating a change in layer 2 address of the user equipment.44. The method of any of claims 38 to 43, further comprising: receiving, from the user equipment, one or more uplink data packets comprising a destination address of a target user plane function; and sending, to the cluster node, the one or more uplink data packets comprising the destination address of the target user plane function and information indicating a layer 2 address of the user equipment, wherein the information indicating the layer 2 address of the user equipment comprises information indicating that the second node is serving the user equipment.45. An apparatus comprising means for performing the method of any of claims 1 to 44.46. An apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform the method of any of claims 1 to 44.47. A computer readable medium comprising instructions, which, when executed by an apparatus, cause the apparatus to perform the method of any of claims 1 to 44.