EP4690962A1

EP4690962A1 - Layer 1/layer 2 triggered mobility (ltm) cell switch procedure

Info

Publication number: EP4690962A1
Application number: EP24719315.4A
Authority: EP
Inventors: Antonino ORSINO; Icaro Leonardo DA SILVA; Pontus Wallentin
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2023-04-06
Filing date: 2024-04-04
Publication date: 2026-02-11
Also published as: CN120937434A; WO2024210808A1

Abstract

In an example, a method performed by a User Equipment (UE) for performing a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch procedure is provided. The method comprises receiving one or more LTM candidate cell configurations, and receiving a LTM cell switch command including an indication of one of the one or more LTM candidate cell configurations. The method also comprises applying the indicated LTM candidate cell configuration to switch to a cell associated with the indicated LTM candidate cell configuration and, in response to applying the indicated LTM candidate cell configuration, sending signalling on the cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

Description

LAYER 1/LAYER 2 TRIGGERED MOBILITY (LTM) CELL SWITCH PROCEDURE

Technical Field

Examples of this disclosure relate to a Layer 1 /Layer 2 Triggered Mobility (LTM) cell switch procedure, for example including a LTM candidate cell configuration. Background

In 3GPP Release 18, a work item known as Further NR mobility enhancements has been agreed. This work item includes a technical area entitled L1/L2 based inter-cell mobility. According to the Work Item Description, WID (RP-223520, 3GPP work item description: Further NR mobility enhancements, MediaTek Inc, Apple, 3GPP TSG RAN Meeting #98-e, Electronic Meeting, December 12-16, 2022), when the UE moves from the coverage area of one cell to another cell, at some point a serving cell change needs to be performed.

Currently serving cell change is triggered by L3 measurements and is done by RRC signalling triggered Reconfiguration with Synchronisation for change of PCell and PSCell, as well as release add for SCells when applicable. All cases involve complete L2 (and L1) resets, leading to longer latency, larger overhead and longer interruption time than beam switch mobility. The goal of L1/L2 based inter-cell mobility is to enable a serving cell change via L1/L2 signalling, in order to reduce the latency, overhead and interruption time.

In this work item, according to the WID, the following is included as one objective of the work:

1 . To specify mechanism and procedures of L1/L2 based inter-cell mobility for mobility latency reduction: o Configuration and maintenance for multiple candidate cells to allow fast application of configurations for candidate cells [RAN2, RAN3] o Dynamic switch mechanism among candidate serving cells (including SpCell and SCell) for the potential applicable scenarios based on L1/L2 signalling [RAN2, RAN1] o L1 enhancements for inter-cell beam management, including L1 measurement and reporting, and beam indication [RAN1 , RAN2]

- Note 1: Early RAN2 involvement is necessary, including the possibility of further clarifying the interaction between this bullet with the previous bullet o Timing Advance management [RAN1 , RAN2] o CU-DU interface signaling to support L1/L2 mobility, if needed [RAN3] Note 2: FR2 specific enhancements are not precluded, if any.

Note 3: The procedure of L1/L2 based inter-cell mobility are applicable to the following scenarios:

■ Standalone, CA and NR-DC case with serving cell change within one CG

■ Intra-DU case and intra-CU inter-DU case (applicable for Standalone and CA: no new RAN interfaces are expected)

■ Both intra-frequency and inter-frequency

■ Both FR1 and FR2

■ Source and target cells may be synchronized or non-synchronized

In 3GPP, discussions have started on solutions for L1/L2 based inter-cell mobility (sometimes also referred to as LTM, L1/L2-triggered mobility or lower layer-triggered mobility).

A basic principle with L1/L2-triggered mobility (LTM) is that the UE is pre-configured, by the network, with an RRC configuration per LTM candidate cell, sometimes also known as a LTM candidate cell configuration. Such a LTM candidate cell configuration may be an RRCReconfiguration message (e.g. delta signaling associated to a reference configuration or the UE’s current configuration) or one or more IEs/ fields/ parameters such as CellGroupConfig. The UE performs L1 measurements (e.g. CSI measurements, such as SS- RSRP, L1 RSRP per SSB) on these LTM candidate cells and transmits corresponding L1 measurement reports to the network (e.g. on PUCCH and/or PUSCH). The network then triggers the execution of a LTM cell switch in the UE to one of these LTM candidate cells by transmitting an LTM cell switch command (such as a MAC CE), to the UE, which then connects to the particular LTM candidate cell and switches to an RRC configuration of this LTM candidate cell. The following has also been agreed for the LTM cell switch:

• UE arrival in the target cell needs to be indicated (somehow)

There currently exist certain challenge(s). For example, many details of the procedures for L1/L2-based inter-cell mobility are still open in 3GPP. This applies also for the details of the so called LTM cell switch procedure. So far RAN2 and RAN1 has concluded that a LTM cell switch command in form of a MAC Control Element, MAC CE, is received by the UE and triggers the LTM cell switch procedure. This command contains also the necessary information for the UE to perform the cell switch, including an indication of an LTM candidate cell configuration. When the UE receives this command, it executes the LTM cell switch and the UE arrival in the target cell (i.e. candidate cell indicated in the LTM cell switch command) needs to be indicated (somehow).

One problem is that is not yet specified how, under which conditions and when the UE should indicate its arrival to the target cell. In particular, as the LTM cell switch command is received on by the UE’s MAC entity from the serving cell, and triggers both MAC and RRC actions at the UE, it is not yet defined how the UE indicates its arrival, whether it needs to generate something, transmit, etc. Figure 1 shows the latest signaling flow, for the inter-DU case, captured in TS 38.401.

Summary

Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. For example, in order to address the above challenges, examples of this disclosure include methods for a User Equipment (UE), to execute an LTM cell switch procedure, comprising receiving at least one LTM candidate cell configuration, and further receiving, from a source network node (e.g. S-DU via CU, CU), an LTM cell switch command (e.g. MAC CE) including an indication of the LTM candidate cell configuration (e.g. LTM candidate configuration ID), applying the received indicated LTM candidate cell configuration (that can be a delta configuration with respect the current UE configuration, a complete LTM configuration, or an LTM reference configuration), and sending an LTM cell switch complete signalling to the target candidate cell based on one or more conditions.

One aspect of the present disclosure provides a method performed by a User Equipment, UE, for performing a Layer 1 /Layer 2 Triggered Mobility, LTM, cell switch procedure. The method comprises receiving one or more LTM candidate cell configurations, and receiving a LTM cell switch command including an indication of one of the one or more LTM candidate cell configurations. The method also comprises applying the indicated LTM candidate cell configuration to switch to a cell associated with the indicated LTM candidate cell configuration, and in response to applying the indicated LTM candidate cell configuration, sending signalling on the cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

Another aspect of the present disclosure provides a method performed by a network node for causing a User Equipment, UE, to perform a Layer 1 /Layer 2 Triggered Mobility, LTM, cell switch procedure, wherein the network node is associated with a serving cell of the UE. The method comprises sending, to the UE, one or more LTM candidate cell configurations and sending, to the UE, a LTM cell switch command including an indication of one of the one or more LTM candidate target cell configurations. The method also comprises receiving signalling from the UE on a cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

A further aspect of the present disclosure provides a method performed by a network node, wherein the network node is associated with a cell associated with a L1/L2-triggered mobility, LTM, candidate cell configuration for a LTM cell switch procedure by a User Equipment, UE. The method comprises receiving signalling from the UE on the cell associated with the LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

A further aspect of the present disclosure provides apparatus in a User Equipment, UE, for performing a Layer 1/Layer 2 Triggered Mobility, LTM, cell switch procedure. The apparatus comprises a processor and a memory. The memory contains instructions executable by the processor such that the apparatus is operable to receive one or more LTM candidate target cell configurations, receive a LTM cell switch command including an indication of one of the one or more LTM candidate cell configurations, apply the indicated LTM candidate cell configuration to switch to a cell associated with the indicated LTM candidate cell configuration, and in response to applying the indicated LTM candidate cell configuration, send signalling on the cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

A still further aspect of the present disclosure provides apparatus in a network node for causing a User Equipment, UE, to perform a Layer 1/Layer 2 Triggered Mobility, LTM, cell switch procedure, wherein the network node is associated with a serving cell of the UE. The apparatus comprises a processor and a memory. The memory contains instructions executable by the processor such that the apparatus is operable to send, to the UE, one or more LTM candidate target cell configurations, send, to the UE, a LTM cell switch command including an indication of one of the one or more LTM candidate target cell configurations, and receive signalling from the UE on a cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

An additional aspect of the present disclosure provides apparatus in a network node, wherein the network node is associated with a cell associated with a L1/L2-triggered mobility, LTM, candidate cell configuration for a LTM cell switch procedure by a User Equipment, UE. The apparatus comprises a processor and a memory. The memory contains instructions executable by the processor such that the apparatus is operable to receive signalling from the UE on the cell associated with the LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

Another aspect of the present disclosure provides apparatus in a User Equipment, UE, for performing a Layer 1/Layer 2 Triggered Mobility, LTM, cell switch procedure. The apparatus is configured to receive one or more LTM candidate target cell configurations, receive a LTM cell switch command including an indication of one of the one or more LTM candidate cell configurations, apply the indicated LTM candidate cell configuration to switch to a cell associated with the indicated LTM candidate cell configuration, and in response to applying the indicated LTM candidate cell configuration, send signalling on the cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

A further aspect of the present disclosure provides apparatus in a network node for causing a User Equipment, UE, to perform a Layer 1/Layer 2 Triggered Mobility, LTM, cell switch procedure, wherein the network node is associated with a serving cell of the UE. The apparatus is configured to send, to the UE, one or more LTM candidate target cell configurations, send, to the UE, a LTM cell switch command including an indication of one of the one or more LTM candidate target cell configurations, and receive signalling from the UE on a cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

Another aspect of the present disclosure provides apparatus in a network node, wherein the network node is associated with a cell associated with a L1/L2-triggered mobility, LTM, candidate cell configuration for a LTM cell switch procedure by a User Equipment, UE. The apparatus is configured to receive signalling from the UE on the cell associated with the LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

Brief Description of the Drawings

For a better understanding of the embodiments of the present disclosure, and to show how it may be put into effect, reference will now be made, by way of example only, to the accompanying drawings, in which: Figure 1 shows the latest signaling flow for the inter-DU case captured in TS 38.401 ;

Figure 2 shows a method performed by a wireless device according to embodiments of the disclosure;

Figure 3 shows a method performed by a network node according to embodiments of the disclosure;

Figure 4 shows a method performed by a second core network entity according to embodiments of the disclosure;

Figure 5 illustrates an example of a system structure;

Figure 6 shows an example of a signaling flow in a method according to examples of this disclosure;

Figure 7 shows an example of a signaling flow in a method according to examples of this disclosure for the case when the C-DU receives the LTM cell switch complete signaling;

Figure 8 shows an example of a signaling flow in a method according to examples of this disclosure for the case when the C-DU does not receive the LTM cell switch complete signaling;

Figure 9 shows an example of a communication system in accordance with some embodiments;

Figure 10 shows a UE in accordance with some embodiments;

Figure 11 shows a network node in accordance with some embodiments;

Figure 12 is a block diagram of a host in accordance with various aspects described herein;

Figure 13 is a block diagram illustrating a virtualization environment in which functions implemented by some embodiments may be virtualized;

Figure 14 shows a communication diagram of a host communicating via a network node with a UE over a partially wireless connection in accordance with some embodiments; and

Figure 15 shows a network node in accordance with further embodiments.

Detailed Description of Example Embodiments

Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

This disclosure refers to the term “L1/L2 based inter-cell mobility” as used in the Work Item Description in 3GPP, though it interchangeably also uses the terms L1/L2 mobility, L1- mobility, L1 based mobility, L1/L2-centric inter-cell mobility, L1/L2 inter-cell mobility L1/L2- Triggered Mobility, Lower-layer triggered Mobility or LTM. The basic principle is that the UE receives a lower layer signaling from the network indicating to the UE a change (or switch or activation) of its serving cell (e.g. change of PCell, from a source to a target PCell), wherein a lower layer signaling is a message/ signaling of a lower layer protocol, which may be referred as a L1/L2 inter-cell mobility execution command or LTM cell switch command. The change of serving cell (e.g. change of PCell) may also lead to a change in Scell(s) for the same cell group e.g. in case the command triggers the UE to change to another cell group configuration of the same type (e.g. another MCG configuration). Before the UE receives the LTM cell switch command, the UE is configured by the network with one or more LTM candidate cell configurations (e.g. reception of an RRC Reconfiguration message, with at least one LTM candidate cell configuration) A LTM candidate cell configuration may include parameters in the IE CellGroupConfig for an LTM candidate cell and/or an embedded RRC Reconfiguration for an LTM candidate cell.

The term LTM cell switch procedure refers to the process of a UE switching (or changing) its cell from a source cell to a target cell (which may be called here an LTM candidate cell or a neighbour cell), using L1/L2-triggered mobility (LTM). In the context of L1/L2-triggered mobility (LTM), an LTM cell switch procedure may sometimes also be known as L1/L2 based inter-cell mobility execution, LTM execution, dynamic switch, LTM switch, (LTM) cell switch, (LTM) serving cell change or (LTM) cell change. In the context of examples of this disclosure, switching to the LTM candidate cell configuration comprises the UE considering that an LTM candidate cell becomes its new special cell (SpCell) e.g. PCell in case of LTM being configured for a Master Cell Group (MCG) and/or PSCell in case of LTM being configured for a Secondary Cell Group (SCG); or, changing its SpCell from the current PCell to an LTM candidate cell.

Even if the term switch or change of cells is used, that may comprise a switch or change of a whole cell group configuration, which includes a change in the SpCell (e.g. change of PCell, or change of PSCell) and a change in SCells of the cell group (e.g. addition, modification and/or release of one or more SCells).

This disclosure refers to a LTM candidate cell, which is a cell the UE is configured with when configured with L1/L2-triggered mobility. That is a cell the UE can move to in a LTM cell switch procedure, upon reception of a LTM cell switch command. Such cells may also be called candidate cell(s), candidates, mobility candidates, non-serving cells, additional cells, target candidate cell, target candidate, etc. A LTM candidate cell is a cell the UE may perform measurements on (e.g. CSI measurements) so that the UE reports these measurements and network may take educated decision on which beam (e.g. TCI state) and/or cell the UE is to be switched to. An LTM candidate cell may be a candidate to be a target PCell or PSCell, or an SCell of a cell group (e.g. MCG SCell or a SCG SCell).

This disclosure refers to at least one LTM candidate cell configuration and that the UE has received at least one LTM candidate cell configuration. This is also sometimes referred to as a configuration of a LTM candidate cell, which may be an RRC configuration, such as encapsulated in an RRC Reconfiguration message, that the UE receives when being configured with L1/L2-Triggered Mobility. A LTM candidate cell configuration comprises the configuration which the UE needs to start to operate accordingly when it performs an LTM cell switch procedure to that LTM candidate cell e.g. upon reception of the LTM cell switch command to that LTM candidate cell, which becomes the target cell and the current (new) SpCell, or an SCell in a serving frequency. The LTM candidate cell configuration comprises parameters of a serving cell (or multiple serving cells, such as a cell group), comprising one or more of the groups of parameters, such as an RRCReconfiguration message an IE CellGroupConfig or an IE SpCellConfig (or the IE SCellConfig, in the case of a Secondary Cell). A LTM candidate cell configuration may in one example comprise one or more of: i) the PCell configuration and one or more SCell configuration(s) of a Master Cell Group (MCG); i) the PSCell configuration and one or more SCell configuration(s) of a secondary Cell Group (SCG). The terms (LTM) candidate configuration, LTM configuration, (LTM) candidate target cell configuration, (LTM) target candidate (cell) configuration may be used interchangeably when referring to LTM candidate cell configuration.

The actual LTM candidate cell configuration and its exact content and/or structure of this IE and/or embedded message may be called an RRC model for the candidate configuration, or simply RRC model. An LTM candidate cell configuration comprises the configuration which the UE needs to operate accordingly when it performs (executes) L1/L2 based inter-cell mobility execution to a LTM candidate cell, upon reception of the lower layer signaling (MAC CE) indicating a L1/L2 based inter-cell mobility to a LTM candidate cell (which becomes the target cell and the current (new) PCell, or an SCell in a serving frequency), or upon reception of the lower layer signaling (MAC CE) indicating a L1/L2 based inter-cell mobility to a LTM candidate cell configuration indicated with a candidate configuration identifier, identity or index (sometimes also denoted candidate configuration ID). The UE may be configured with multiple LTM candidate cell configurations, so a Candidate DU (C-DU) generates and sends to the CU multiple configuration(s). The actual LTM candidate cell configuration the UE receives during the LTM configuration may be a delta signaling to be applied on top of a reference configuration, so that the actual configuration the UE is to use in the LTM candidate cell upon LTM cell switch is the combination of the LTM candidate cell configuration and the reference configuration (e.g. separately signaled by the network to the UE). That combination of the LTM candidate cell configuration and the reference configuration the UE uses may also be called a complete LTM candidate cell configuration. For the context of examples of this disclosure, unless stated otherwise, this complete LTM candidate cell configuration may also be considered as an LTM candidate cell configuration.

The term “beam” may correspond to a spatial direction in which a signal is transmitted (e.g. by a network node) or received (e.g. by the UE), or a spatial filter applied to a signal which is transmitted or received. Thus, transmitting signals different beams could correspond to transmitting signals in different spatial directions. When the text refers to a “beam which is selected” it may refer to a beam index and/or a Reference Signal (RS) index or identifier, such as a Synchronization Signal block (SSB) index, or a CSI-RS resource identifier. Thus, selecting a beam may correspond to selecting an SSB, associated to an SSB index. Or, selecting a beam may correspond to selecting a CSI-RS, associated to a CSI-RS resource identifier.

This disclosure refers to “LTM cell switch complete signalling”. This complete signalling may in some examples be used by the UE to indicate to the network that the configuration of the target cell is now in use, that the UE was able to process and decode the configuration of the target cell without any error, and that the LTM cell switch procedure was successful. Here successful means that the UE was able to switch to a new cell according to the received LTM cell switch command and that is ready to receive and send traffic over the new source cell (e.g., the target cell indicated in the LTM cell switch command).

Assuming that the signalling is an RRCReconfigurationComplete message, the UE may in some examples generate generates a complete configuration per LTM candidate by applying LTM candidate delta to a reference configuration, which leads to the generation of the RRCReconfigurationComplete, which is not transmitted until the UE receives an LTM cell switch command indicating that LTM candidate cell.

Assuming that the signalling is an RRCReconfigurationComplete message, the UE may in some examples generate a complete configuration per LTM candidate by applying LTM candidate delta to a reference configuration, which leads to the generation of the RRCReconfigurationComplete, which is not transmitted until the UE receives an LTM cell switch command indicating that LTM candidate cell, but only the first time the UE applies the message for a candidate. UE needs to maintain a UE variable indicating that state e.g. completeTransmitted=’true’, which starts with false when that is configured. If the LTM candidate is modified, that is changed to false again. Assuming that the signalling is an uplink (UL) MAC Control Element (MAC CE), the UE may in some examples generate a complete configuration per LTM candidate by applying LTM candidate delta to a reference configuration, so that the generation of an RRCReconfigurationComplete is skipped (exception in 5.3.5.3) When the UE receives an LTM cell switch command indicating that LTM candidate cell, the UE transmits an LTM cell switch command.

In example methods of this disclosure, the UE first processes the received LTM cell switch command, then applies the indicated LTM candidate cell configuration, and then it sends the LTM cell switch complete signalling, such as an RRCReconfigurationComplete message, on the new cell.

In example methods, when the UE receives at least one LTM candidate cell configuration, e.g. in an LTM configuration, the UE creates/ generates I builds the LTM cell switch complete signalling, but only transmits it when the UE receives the LTM cell switch command, indicating the LTM candidate cell configuration.

In example methods, when the UE receives at least one LTM candidate cell configuration, e.g. in an LTM configuration, the UE creates/ generates I builds the LTM cell switch complete signalling, but only transmits the first time the UE applies the LTM candidate cell configuration for a given LTM candidate cell i.e. subsequent LTM cell switches to an LTM candidate cell do not trigger the UE to transmit the LTM cell switch complete signalling.

Certain embodiments may provide one or more of the following technical advantage(s). For example, examples of this disclosure may enable the UE to perform an LTM cell switch procedure and send a positive acknowledge (referred in the document as LTM cell switch complete signalling e.g. RRCReconfigurationComplete) to the network (e.g. Candidate-DU) when the UE receives the LTM cell switch command, even though that LTM cell switch complete signalling may have been generated when the UE receives the LTM candidate configuration. This may ensure that the network is aware that the received LTM configuration is applied on the configuration the UE uses in the target cell, and not in the source cell.

Examples of this disclosure may also enable the UE to determine when to transmit LTM cell switch complete signalling, such as an RRCReconfigurationComplete message, using the target cell configuration.

In addition, advantages provided by at least some example embodiments may ensure that the UE transmits LTM cell switch complete signalling, e.g. RRCReconfigurationComplete message, to the network during or after execution of the LTM cell switch procedure and not when it received the LTM candidate cell configuration. This may for example avoid the network receiving a message too early relating to the UE applying an LTM candidate cell (e.g. receiving a message when the UE received the LTM candidate cell configuration rather than when it performed the LTM cell switch). Examples of this disclosure may therefore ensure that the protocol states in the UE and network are synchronized, i.e. that network is aware of the current UE configuration.

Figure 2 depicts a method 200 in accordance with particular embodiments, for example a method performed by a User Equipment (UE) for performing a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch procedure. The method 200 may be performed by a UE or wireless device (e.g. the UE QQ112 or UE QQ200 as described later with reference to Figures 9 and 10 respectively). The method 200 begins at step 202 with receiving one or more LTM candidate cell configurations. Step 204 of the method comprises receiving a LTM cell switch command including an indication of one of the one or more LTM candidate cell configurations. Step 206 comprises applying the indicated LTM candidate cell configuration to switch to a cell associated with the indicated LTM candidate cell configuration. Step 208 comprises, in response to applying the indicated LTM candidate cell configuration, sending signalling on the cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

In some examples, the method 200 may comprise generating or preparing the signalling in response to receiving the LTM cell switch command; or after applying the indicated LTM candidate cell configuration; or after the UE has synchronized with the cell associated with the indicated LTM candidate cell configuration; or in response to an indication from a MAC layer. For example, there the method 200 comprises generating or preparing the signalling in response to an indication from a MAC layer, the indication from the MAC layer may for example indicate that the indicated LTM candidate cell configuration has been applied and/or the UE has synchronized with the cell associated with the indicated LTM candidate cell configuration.

In some examples, the method 200 may comprise performing a random access procedure on the cell associated with the indicated LTM candidate cell configuration after applying the indicated LTM candidate cell configuration. In some examples, a message transmitted in the random access procedure (e.g. Msg1 , Msg3 or MsgA) may be the signalling that indicates that the cell switch procedure is complete, though in other examples the signalling may be other signalling. In some examples, the signalling may be sent in step 208 of the method 200 after completion of the random access procedure and/or after receiving, on the cell associated with the indicated LTM candidate cell configuration, a random access response and/or contention resolution information (e.g. Msg2, Msg4 or MsgB). In other examples, the signalling may comprise one or more Radio Resource Control (RRC) messages and/or one or more RRCReconfigurationComplete messages and/or one or more MAC Control Elements (CEs) and/or Layer 1 (L1) signalling.

The method 200 may in some examples comprise generating a complete LTM candidate cell configuration based on the indicated LTM cell configuration (which may be for example an incomplete LTM cell configuration) and a reference configuration. Thus, in some examples, applying the indicated LTM candidate cell configuration in step 206 of the method 200 may comprise applying the complete LTM candidate cell configuration.

In some examples, the method 200 may comprise, in response to receiving the one or more LTM candidate cell configurations in step 202 of the method 200, sending signalling on a serving cell and/or the cell associated with the indicated LTM candidate cell configuration to indicate that the indicated LTM candidate cell configuration has been received and/or decoded and/or applied. Alternatively, in some examples, the method 200 may comprise, in response to receiving the one or more LTM candidate cell configurations in step 202 of the method 200, sending, for each of the one or more LTM candidate cell configurations, signalling on the serving cell and/or a respective cell associated with the LTM candidate cell configuration to indicate that the LTM candidate cell configuration has been received and/or decoded and/or applied.

The one or more LTM candidate cell configurations and/or the LTM cell switch command may in some examples be received from a serving cell and/or a network node associated with the serving cell.

The signalling on the cell associated with the indicated LTM candidate cell configuration may in some examples be sent in step 208 of the method 200 to a network node associated with the cell associated with the indicated LTM candidate cell configuration. That is, for example, the network node may serve or provide the cell.

In some examples, applying the indicated LTM candidate cell configuration in step 206 of the method 200 may be performed by a RRC layer. For example, the RRC layer may apply the indicated LTM candidate cell configuration in response to an indication from a layer lower than the RRC layer. The indication from the layer lower than the RRC layer may in some examples identify the indicated LTM candidate cell configuration. In some examples, the RRC layer may send an indication to the layer lower than the RRC layer after applying the indicated LTM candidate cell configuration. The indicated LTM candidate cell configuration or each of the one or more LTM candidate cell configurations may in some examples comprise one or more of the following non-limiting examples:

• A cell group configuration for a Master Cell Group, MCG, or a Secondary Cell Group, SCG;

• A serving cell configuration for a SpCell, PCell, PSCell or SCell;

• A bandwidth Part, BWP configuration;

• An RRCReconfiguration message;

• A measurement configuration;

• A radio bearer configuration;

• A UE identity or C-RNTI;

• System information;

• A timer configuration;

• Another candidate cell configuration;

• An indication for the UE to perform a full configuration;

• An indication for the UE to perform a delta configuration;

• A reference configuration; and/or

• Indication(s) whether or not to perform L2 reset, MAC reset, partial MAC reset, full MAC reset, RLC re-establishment and/or PDCP recovery or re-establishment.

Figure 3 depicts a method 300 in accordance with particular embodiments, for example a method performed by a network node for causing a User Equipment (UE) to perform a Layer 1/Layer 2 Triggered Mobility (LTM) cell switch procedure, wherein the network node is associated with a serving cell of the UE. The method 300 may be performed by a network node (e.g. the network node QQ110 or network node QQ300 as described later with reference to Figures 9 and 11 respectively). The method 300 begins at step 302 with sending, to the UE, one or more LTM candidate cell configurations. Step 304 of the method 300 comprises sending, to the UE, a LTM cell switch command including an indication of one of the one or more LTM candidate target cell configurations. Step 306 comprises receiving signalling from the UE on a cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

The The method of claim 17, wherein the signalling comprises one or more RRC messages and/or one or more RRCReconfigurationComplete messages and/or one or more MAC Control Elements, CEs, and/or Layer 1 , L1 , signalling.

Figure 4 depicts a method 400 in accordance with particular embodiments, for example a method performed by a network node, wherein the network node is associated with a cell associated with a L1/L2-triggered mobility, LTM, candidate cell configuration for a LTM cell switch procedure by a User Equipment, UE. The method 400 may be performed by a network node (e.g. the network node QQ110 or network node QQ300 as described later with reference to Figures 9 and 11 respectively). The method 400 begins at step 402 with receiving signalling from the UE on the cell associated with the LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

The signalling may in some examples be received in step 402 after the UE has synchronized with the cell associated with the LTM candidate cell configuration. The signalling may comprise for example one or more RRC messages and/or one or more RRCReconfigurationComplete messages and/or one or more MAC Control Elements, CEs, and/or Layer 1 , L1 , signalling. The method 400 may also in some examples comprise receiving the signalling in response to the LTM candidate cell configuration including or being associated with an indication to send the signalling on the cell.

Particular example embodiments will now be described.

Figure 5 illustrates an example of a system structure including the entities involved in examples of this disclosure. The User Equipment (UE) 1001 is a wireless terminal, such as a cellular smartphone, sometimes connected to the source network node 1002 over a wireless interface 1004 and sometimes connected to a target network node 1003, to which the UE

1001 is connected over a wireless interface 1005.

In the context of a mobility procedure, such as a LTM cell switch procedure, for the UE, the source network node 1002, sometimes also referred to as the serving network node, controls a source cell 1009 (sometimes called serving cell or Special Cell (SpCell)). The target network node 1003 controls a target cell 1010 (sometimes called neighbour cell, candidate cell or LTM candidate cell). Each of source network node 1002 and the target network node 1003 may be a base station such as e.g. gNB, or, e.g. in case of a distributed CU/DU RAN architecture, a distributed unit, sometimes known as either gNB-DU or DU. Hence the source network node 1002 corresponds to a source DU, S-DU, sometimes also known as serving DU, and the target network node 1003 corresponds to a target DU. T-DU (sometimes called neighbour DU or candidate DU, C-DU). Both the source network node

1002 and the target network node 1003 are connected to a third network node 1006, sometime also referred to as serving network node. The source network node and the target network node may be the same network node. In some scenarios the source network node 1002 and the target network node 1003 may be connected to different third network nodes 1006. Further, the third network node 1006 may, e.g. in case of a distributed CU/DU RAN architecture, be a central unit, CU, sometimes referred to as the serving CU, known as either a gNB-CU, CU, gNB-CU-CP or gNB-CU-UP, or a core network node such as an User Plane Function, UPF or an Access and Mobility management Function, AMF.

In an example according to this disclosure, a method for a User Equipment, UE, to transmit an LTM cell switch complete signalling (e.g. RRCReconfigurationComplete or UL MAC CE), comprises receiving at least one LTM candidate cell configuration, further receiving, from a source network node, an LTM cell switch command (e.g. a MAC CE), including an indication of an LTM candidate cell configuration, applying (or start using, switching to) the received indicated LTM candidate cell configuration and in response sending an LTM cell switch complete signalling according to one or more rules. The UE may in some examples generate (e.g. builds, creates, constructs, sets its content) the LTM cell switch complete signalling upon the reception of the LTM candidate cell configuration from the source node (e.g. CU and/or S-DU). In one example, the generation of the LTM cell switch complete signalling is included within the received LTM candidate cell configuration. Therefore, the LTM candidate cell configuration will configure/instruct the UE to also generate the LTM cell switch complete signalling. In another example, the trigger for the generation of the LTM cell switch complete signalling is the reception of the LTM candidate cell configuration itself (regardless if the UE process the content of the LTM candidate cell configuration or not). In other words, the UE generates the LTM cell switch complete signalling in response to the reception of the LTM candidate cell configuration. In one example, when the UE receives the LTM candidate cell configuration (e.g. RRCReconfiguration message) the UE generates a complete LTM candidate cell configuration, by applying the LTM candidate cell configuration on top of a reference configuration e.g. by performing the actions as specified in § 5.3.5.3 of 3GPP 38.331 . When the UE generates the complete LTM candidate cell configuration the UE also generates the LTM cell switch complete signalling (e.g. an RRCReconfigurationComplete), but the UE does not transmit it until it receives the LTM cell switch command. When the UE is configured with a number of K LTM candidate cells, and generates K complete LTM candidate cell configurations, and the UE also generates K LTM cell switch complete signaling. When the UE receives the LTM cell switch command indicating one of the LTM candidate cells, the UE applies the complete LTM candidate cell configuration which has been generated (associated to the indicated LTM candidate cell) and, after it switches to the LTM candidate cell, it transmits the generated LTM cell switch complete signalling to the LTM candidate cell. At the network side, the C-DU may in some examples receive the LTM cell switch complete signalling e.g. an RRCReconfigurationComplete message, and transmit to the CU in an UL RRC MESSAGE TRANSFER, possibly also transmits to the CU an ACCESS SUCCESS message including the Target cell ID of the LTM candidate cell, as shown in the signaling flow in Figure 6, which shows an example of a signaling flow in a method according to examples of this disclosure.

The UE may in some examples generate the LTM cell switch complete signalling upon the reception of an LTM cell switch command. In one example the trigger for the generation of the LTM cell switch complete signalling is included within the received LTM cell switch command. Therefore, the LTM cell switch command will configure/instruct the UE to also generate the LTM cell switch complete signalling. In another example, the trigger for the generation of the LTM cell switch complete signalling is the reception of the LTM cell switch command itself (regardless if the UE process the content of the LTM cell switch command or not). In another example, when the UE receives the LTM candidate cell configuration (e.g. RRCReconfiguration message) the UE generates a complete LTM candidate cell configuration, by applying the LTM candidate cell configuration on top of a reference configuration by performing the actions as specified in § 5.3.5.3 of 3GPP 38.331.

When the UE generates the complete LTM candidate cell configuration, e.g., by performing the actions as specified in § 5.3.5.3 of 3GPP 38.331 , the UE may in some examples skip the step of generating an RRCReconfigurationComplete. For example, an exception may be added to the procedure so that when the UE is applying the procedure (e.g. 5§5.3.5.3 of 3GPP TS 38.331) for generating the complete LTM candidate cell, the UE does not generate (build, create, set) the RRCReconfigurationComplete message. When the UE receives the LTM cell switch command indicating one of the LTM candidate cells, the UE applies the complete LTM candidate cell configuration which has been generated (associated to the indicated LTM candidate cell) and, after it switches to the LTM candidate cell, it generates an LTM cell switch complete signalling (e.g. an UL MAC CE) and transmits to the LTM candidate cell. The steps could be as follows in some examples:

■ UE receives the LTM candidate cell configuration;

■ UE (MAC entity) furthers receives the LTM cell switch command and indicates that to upper/ higher layers (RRC entity)

■ UE (MAC entity) receives an indication from upper layers (e.g. RRC entity) that the LTM candidate cell configuration has been applied. UE (MAC entity) generates the LTM cell switch complete signalling (e.g. UL MAC CE) and transmits to the LTM candidate cell (e.g. by submitting to a MAC buffer and/or submitting to lower layers).

The UE may in some examples generate the LTM cell switch complete signalling only after that the LTM cell switch procedure has been successfully completed. In one example, the generation of the LTM cell switch complete signalling is done only after that the UE has performed the actions included in the LTM cell switch command, and applied the indicated LTM candidate cell configuration within the LTM cell switch command, or, only after the UE has synchronized with the LTM candidate cell and applied the complete LTM candidate configuration and possibly other fields from the LTM cell switch command. Since the reception and application of the LTM cell switch command and LTM candidate cell configuration may happen on different layers of the UE protocol stack (e.g., the LTM cell switch command may corresponds to a MAC CE and the LTM candidate cell configuration may correspond to an RRC message e.g. RRCReconfiguration), the indication that the LTM cell switch procedure is finished may come from multiple layers. In one example, the indication that the LTM cell switch procedure may come from the MAC layer and is when the LTM cell switch command has been processed and applied. In one example, the indication that the LTM cell switch procedure may come from the RRC layer and is when the LTM candidate cell configuration has been processed and applied. In one example, the indication that the LTM cell switch procedure is when both the MAC and RRC layer indicated that the LTM cell switch command and LTM candidate cell configuration has been processed and applied.

The UE may in some examples generate the LTM cell switch complete signalling only after that a random access procedure, due to an LTM cell switch procedure, has been successfully completed. In one option the UE transmits the LTM cell switch complete signalling to the LTM candidate cell after the UE receives a MAC CE from the network for contention resolution (in the case of a contention based random access procedure) or, after the UE receives a Random Access Response MAC CE from the network (in the case of a an LTM cell switch with contention free random access procedure).

The LTM cell switch complete signalling may in some examples be an RRC message, such as a RRCReconfigurationComplete message or a new RRC message for LTM. The LTM cell switch complete signalling may in some examples be a MAC CE. The UE may in some examples transmit to a target node the LTM cell switch complete signalling, only upon receiving an indication that the LTM cell switch procedure has been successfully completed. The LTM cell switch complete signalling may in some examples be the last signalling sent by the UE and that conclude the LTM cell switch procedure. This also mean that the UE has processed and completed all the actions that are included in the received LTM cell switch command. The indication that the LTM cell switch procedure has been completed may in some examples be received by the MAC or RRC layer.

The UE may in some examples transmit to a target node the LTM cell switch complete signalling, upon receiving an indication that a LTM cell switch command has been received and that a LTM candidate cell configuration needs to be applied. The LTM cell switch complete signalling may for example indicate to the network that the UE has started to use the LTM candidate cell configuration indicated in the received LTM cell switch command but that the LTM cell switch procedure is not yet completed as the UE has not yet applied all the configurations received in the LTM cell switch command. In order to indicate to the network that the LTM cell switch procedure has been successfully complete a further uplink signalling will be sent from the UE to the network. The indication that the LTM cell switch procedure has been completed may in some examples be received by the MAC or RRC layer.

The UE may in some examples transmit to a target node the LTM cell switch complete signalling, upon receiving an indication included in the LTM cell switch command, wherein the indication indicates that the UE shall transmit the LTM cell switch complete signalling to the LTM candidate cell in the LTM cell switch. When the indication is not included, the UE instead starts monitoring PDCCH in the LTM candidate cell, instead of starting by transmitting the LTM cell switch complete message. That indication could be included in the LTM cell switch command the first time the UE needs to apply the LTM candidate configuration or when the network has some uncertainty about the timing the UE starts to monitor PDCCH on the LTM candidate cell e.g. in inter-DU scenarios and/or when the LTM candidate cell is in a different DU than the serving cell the UE comes from. In other words, the LTM cell switch complete signalling is not always transmitted, but when requested by the network in the LTM cell switch command.

The UE may in some examples generate and/or transmit to a target node the LTM cell switch complete signalling, upon obtaining an indication associated to the LTM candidate cell configuration. This may be a field in the LTM candidate cell configuration and/or associated to it, so that when the UE applies the the LTM candidate cell configuration e.g. to generate the complete LTM candidate cell configuration (on top of the reference configuration) the UE determines whether it needs to generate and/or transmit upon LTM cell switch the LTM cell switch complete signalling for that particular LTM candidate cell. The reasoning could be that for certain LTM candidate cells, there is no need to generate and/or transmit an LTM cell switch complete signalling, because of the higher certainty in terms of timing the UE is able to received PDCCH in the LTM candidate cell after the cell switch procedure, e.g., for LTM candidate cells in the same DU.

The UE may in some examples determine to generate and/or transmit to a target node (e.g. C-DU, CU) the LTM cell switch complete signalling, upon obtaining an indication associated to a set of LTM candidate cell(s). When the UE is performing an LTM cell switch from a serving cell within the set to an LTM candidate cell within the same set, the UE may in some examples not generate and/or transmit the LTM cell switch complete signalling. When the UE is performing an LTM cell switch from a serving cell within a set to an LTM candidate cell from another set, the UE may in some examples generate and transmit the LTM cell switch complete signalling. Such a set may for example be configured at the UE by the network e.g. set 1 : LTM candidate A, LTM candidate B, LTM candidate C; set 2: LTM candidate D, LTM candidate E, LTM candidate F. When the UE performs LTM cell switch between A->B, B->A, A->C, C->A, B->C, C->B the UE may in some examples not generate and/or transmit the LTM cell switch complete signalling; However, when the UE performs LTM cell switch between cells from different sets the UE generates and transmits the LTM cell switch complete signalling e.g. A-> F.

The UE may in some examples transmit to a target node the LTM cell switch complete signalling upon the reception of an LTM candidate cell configuration by the source node, even if an LTM cell switch procedure has not initiated. The UE may in some examples be configured with one or more LTM candidate cell configuration by the source node and the UE will send an LTM cell switch complete signalling to indicate to the target node that the LTM candidate cell configuration has been correctly received and decoded. In one example, the UE sends one LTM cell switch complete signalling for each LTM candidate cell configuration received.

The UE may in some examples transmit the LTM cell switch complete signalling to the source node. The UE may in some examples be configured with one or more LTM candidate cell configuration by the source node and the UE will send an LTM cell switch complete signalling to indicate to the target node that the LTM candidate cell configuration has been correctly received and decoded. In one example, the UE sends one LTM cell switch complete signalling for each LTM candidate cell configuration received. In one example, the UE sends one LTM cell switch complete signalling that include an indication of all the LTM candidate cells configurations that have been correctly received and decoded.

The UE may in some examples be configured with a first cell group and a second cell group and transmits the LTM cell switch complete signalling for a LTM candidate cell configuration received for a second cell group. The UE may in some examples transmit the LTM cell switch complete signalling in the first cell group. The UE may in some examples transmit the LTM cell switch complete signalling in the second cell group. The first cell group may in some examples be a Master Cell Group (MCG) and the second cell group a Secondary Cell Group (SCG). The first cell group may in some examples be a Secondary Cell Group (SCG) and the second cell group a Master Cell Group (MCG)

The UE may in some examples transmit the LTM cell switch complete signalling upon the completion of an LTM cell switch procedure only after that an LTM cell switch procedure has been initiated for the first time for the LTM candidate cell configuration. If subsequent LTM cell switch procedures are initiated for the same LTM candidate cell configuration the UE does not transmit an LTM cell switch complete signalling (but a different uplink signalling and/or the UE first starts monitoring PDCCH in the LTM candidate cell upon LTM cell switch, unless the UE has UL data in buffer to transmit). In one example, the UE has a counter for each LTM candidate cell configuration received by the source node and this counter is initialized to zero (0). In case a first LTM cell switch procedure is initiated for a certain LTM candidate cell configuration, the counter for the LTM candidate cell configuration is increased by one (+1). If the counter for the LTM candidate cell configuration is more than zero, for each subsequent LTM cell switch procedure initiated for the LTM candidate cell configuration the UE transmit an uplink signalling that is not the LTM cell switch complete signalling. In one example, the UE has a 1 -bit indicator for each LTM candidate cell configuration received by the source node and this 1 -bit indicator has a value to indicate whether at least one LTM cell switch procedure is initiated for a certain LTM candidate cell configuration (e.g., value 0 indicate no LTM cell switch procedure initiated for a certain LTM candidate cell configuration). In case a first LTM cell switch procedure is initiated for a certain LTM candidate cell configuration, the value of the 1-bit indicator for the LTM candidate cell configuration is changed to indicate that at least one LTM cell switch procedure has been initiated for a certain LTM candidate cell configuration (e.g., value 0 indicate at least one LTM cell switch procedure initiated for a certain LTM candidate cell configuration). Based on the example, if the value of the 1-bit indicator is 1 for a LTM candidate cell configuration, for each subsequent LTM cell switch procedure initiated for the LTM candidate cell configuration the UE transmit an uplink signalling that is not the LTM cell switch complete signalling. In one example, the uplink signalling that the UE transmit for the subsequent LTM cell switch procedure initiated for the LTM candidate cell configuration is a MAC CE. In one example, the uplink signalling that the UE transmit for the subsequent LTM cell switch procedure initiated for the LTM candidate cell configuration is a RRC message (a new or an existing one). In one example, the uplink signalling that the UE transmit for the subsequent LTM cell switch procedure initiated for the LTM candidate cell configuration is a L1 signalling.

The UE may in some examples be configured with a first cell group and a second cell group and transmits the LTM cell switch complete signalling upon the completion of an LTM cell switch procedure initiated for a LTM candidate cell configuration for a second cell group. The UE may in some examples transmit the LTM cell switch complete signalling in the first cell group. The UE may in some examples transmit the LTM cell switch complete signalling in the second cell group. The first cell group may in some examples be a Master Cell Group (MCG) and the second cell group a Secondary Cell Group (SCG). The first cell group may in some examples be a Secondary Cell Group (SCG) and the second cell group a Master Cell Group (MCG).

The LTM candidate cell configuration may in some examples include the LTM cell switch complete signalling. The UE may in some examples transmit the LTM cell switch complete signalling in the LTM candidate cell configuration upon execution of an LTM cell switch procedure initiated for the LTM candidate cell configuration. The UE may in some examples transmit the LTM cell switch complete signalling in the LTM candidate cell configuration upon reception of the LTM candidate cell configuration.

In some examples, based on different rules disclosed above, the UE may or may not transmit the LTM cell switch complete signalling. Thus, at the C-DU, the C-DU may or may not expect the LTM cell switch complete signalling.

In some examples, the LTM candidate cell configuration, for a given LTM candidate cell, may be provided to the UE in an RRCReconfiguration (in a series of nested Information Elements (IEs)) the UE receives from a serving cell e.g. while connected to the S-DU. That RRCReconfiguration includes a field/IE corresponding to an LTM configuration (e.g. LTM- CandidateConfig) and the LTM candidate cell configuration is included in that LTM configuration, as shown in the example below:

OPTIONAL

}

Within the LTM configuration the UE obtains the one or more LTM candidate cell configuration(s), in an AddMod list e.g. LTM-CandidateToAddModList, as shown below:

Each LTM candidate cell configuration corresponds to an element in the AddMod list and is associated to an LTM candidate identifier (ID) e.g. ltm-Candidateld-r18 or IE LTM-

Candidateld-r18, as shown below:

LTM-Candidate-rl 8 : : = SEQUENCE {

Ltm-CandidateId-rl 8 LTM-CandidateI d-rl 8 ,

Itm-Conf i g-r! 8 OCTET STRING ( CONTAINING

RRCReconfiguration ) , possibly in the form of e.g. an RRCReconfiguration message.

In some examples, the indication of the LTM configuration included in the LTM cell switch command the UE receives may correspond to an LTM candidate configuration ID e.g. Itm- Candidateld-r18 of IE LTM-Candidateld-r18,. Which points to one of the LTM candidate configuration(s) the UE applies I switches to I starts using upon LTM cell switch.

In some examples, the UE generating the LTM cell switch complete signalling comprises the UE creating and/or building and/or setting the content of the LTM cell switch complete signalling.

Examples of this disclosure include methods for a source network node, such as a source gNB, a source DU or a source CU, to handle the reception of LTM cell switch complete signalling from a UE, comprising receiving an LTM cell switch complete signalling that is related to a LTM candidate cell configuration.

Examples of this disclosure include methods for a target network node, such as a target gNB, a target DU, or a target CU, to handle the reception of LTM cell switch complete signalling from a UE, comprising receiving an LTM cell switch complete signalling that is related to a LTM candidate cell configuration and in response, transmitting to the CU the LTM cell switch complete signalling.

In some examples, the C-DU receives the LTM cell switch complete signalling which corresponds to an RRCReconfigurationComplete and, upon reception, the C-DU transmits to the CU an UL RRC MESSAGE TRANSFER including the received RRCReconfigurationComplete. In one option, the C-DU also transmits to the CU an ACCESS SUCCESS message including the Target Cell ID of the LTM candidate cell the UE has accessed (i.e. the cell in which the UE transmits the RRCReconfigurationComplete).

This is illustrated below in a signaling flow.

Examples of this disclosure include methods for a target network node, such as a target gNB, a target DU, or a target CU, comprising:

• Determining whether an LTM cell switch complete signalling corresponding to an RRCReconfigurationComplete related to a LTM candidate cell configuration has been received or not, when a UE performs an LTM cell switch in the target network node;

• In response to determining that the LTM cell switch complete signalling has been received, transmitting the LTM cell switch complete signalling to the CU (e.g. an RRCReconfigurationComplete within an UL RRC MESSAGE TRANSFER);

• and, in response to determining that the LTM cell switch complete signalling has not been received, transmitting an ACCESS SUCCESS message to the CU (e.g. including the Target cell ID of the LTM candidate cell which the UE accessed).

This is illustrated below in the signaling flow in Figure 7, which shows an example of a signaling flow in a method according to examples of this disclosure for the case when the C- DU receives the LTM cell switch complete signaling. Figure 8 on the other hand shows an example of a signaling flow in a method according to examples of this disclosure for the case when the C-DU does not receive the LTM cell switch complete signaling.

In some examples, the C-DU may transmit the UL MESSAGE TRANSFER including the RRCReconfigurationComplete message, also including the Target cell ID (which otherwise would have been included in an Access success, which according to C1 is not transmitted as the C-DU has received from the UE the LTM cell switch complete signaling.

Examples of this disclosure include methods for a third network node (or serving network node), such as a (serving) Central Unit (CU), (serving) gNB-CU, to handle the reception of LTM cell switch complete signalling from a UE, comprising determining whether an LTM cell switch complete signalling corresponding to an RRCReconfigurationComplete related to a LTM candidate cell configuration has been received or not, when a UE performs an LTM cell switch by performing one of: o Receiving, from a target network node, LTM cell switch complete signalling (e.g. an RRCReconfigurationComplete within an UL RRC MESSAGE TRANSFER); o Receiving, from a target network node, an ACCESS SUCCESS message (e.g. including the Target cell ID of the LTM candidate cell which the UE accessed).

The third network node may in some examples transmit an indication to the source network node an indication of the reception of the LTM cell switch complete signalling. The UE may in some examples be configured with a first cell group and a second cell group and the third network node controls the first cell group. The third network node may in some examples transmit an indication to a fourth network node, controlling the second cell group, an indication of the reception of the LTM cell switch complete signalling. The UE may in some examples be configured with a first cell group and a second cell group and the third network node controls the second cell group. The third network node may in some examples transmit an indication to a fourth network node, controlling the first cell group, an indication of the reception of the LTM cell switch complete signalling. The first cell group may in some examples be a Master Cell Group (MCG) and the second cell group a Secondary Cell Group (SCG). The first cell group may in some examples be a Secondary Cell Group (SCG) and the second cell group a Master Cell Group (MCG).

Examples of this disclosure include methods for a fourth network node (or serving network node), such as a (serving) Central Unit (CU), (serving) gNB-CU, to handle the reception of LTM cell switch complete signalling from a UE, configured with a first cell group and a second cell group, comprising receiving, from a third network node, an indication of the reception of the LTM cell switch complete signalling. The fourth network node may in some examples control the second cell group. The fourth network node may in some examples control the first cell group. The first cell group may in some examples be a Master Cell Group (MCG) and the second cell group a Secondary Cell Group (SCG). The first cell group may in some examples be a Secondary Cell Group (SCG) and the second cell group a Master Cell Group (MCG)

Figure 9 shows an example of a communication system QQ100 in accordance with some embodiments. In the example, the communication system QQ100 includes a telecommunication network QQ102 that includes an access network QQ104, such as a radio access network (RAN), and a core network QQ106, which includes one or more core network nodes QQ108. The access network QQ104 includes one or more access network nodes, such as network nodes QQ110a and QQ110b (one or more of which may be generally referred to as network nodes QQ110), or any other similar 3^rd Generation Partnership Project (3GPP) access nodes or non-3GPP access points. Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network QQ102 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network QQ102 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network QQ102, including one or more network nodes QQ110 and/or core network nodes QQ108.

Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU-CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an A1 , F1 , W1 , E1 , E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an 0-2 interface defined by the O-RAN Alliance or comparable technologies. The network nodes QQ110 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs QQ112a, QQ112b, QQ112c, and QQ112d (one or more of which may be generally referred to as UEs QQ112) to the core network QQ106 over one or more wireless connections. Example wireless communications over a wireless connection include transmitting and/or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and/or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system QQ100 may include any number of wired or wireless networks, network nodes, UEs, and/or any other components or systems that may facilitate or participate in the communication of data and/or signals whether via wired or wireless connections. The communication system QQ100 may include and/or interface with any type of communication, telecommunication, data, cellular, radio network, and/or other similar type of system.

The UEs QQ112 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and/or operable to communicate wirelessly with the network nodes QQ110 and other communication devices. Similarly, the network nodes QQ110 are arranged, capable, configured, and/or operable to communicate directly or indirectly with the UEs QQ112 and/or with other network nodes or equipment in the telecommunication network QQ102 to enable and/or provide network access, such as wireless network access, and/or to perform other functions, such as administration in the telecommunication network QQ102.

In the depicted example, the core network QQ106 connects the network nodes QQ110 to one or more hosts, such as host QQ116. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network QQ106 includes one more core network nodes (e.g., core network node QQ108) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and/or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node QQ108. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), Policy Control Function (PCF) and/or a User Plane Function (UPF).

The host QQ116 may be under the ownership or control of a service provider other than an operator or provider of the access network QQ104 and/or the telecommunication network QQ102, and may be operated by the service provider or on behalf of the service provider. The host QQ116 may host a variety of applications to provide one or more services. Examples of such applications include the provision of live and/or pre-recorded audio/video content, data collection services, for example, retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

As a whole, the communication system QQ100 of Figure 9 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and/or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and/or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and/or any low- power wide-area network (LPWAN) standards such as LoRa and Sigfox.

In some examples, the telecommunication network QQ102 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunications network QQ102 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network QQ102. For example, the telecommunications network QQ102 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and/or Massive Machine Type Communication (mMTC)ZMassive loT services to yet further UEs.

In some examples, the UEs QQ112 are configured to transmit and/or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network QQ104 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network QQ104. Additionally, a UE may be configured for operating in single- or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved- UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).

In the example illustrated in Figure 9, the hub QQ114 communicates with the access network QQ104 to facilitate indirect communication between one or more UEs (e.g., UE QQ112c and/or QQ112d) and network nodes (e.g., network node QQ110b). In some examples, the hub QQ114 may be a controller, router, a content source and analytics node, or any of the other communication devices described herein regarding UEs. For example, the hub QQ114 may be a broadband router enabling access to the core network QQ106 for the UEs. As another example, the hub QQ114 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes QQ110, or by executable code, script, process, or other instructions in the hub QQ114. As another example, the hub QQ114 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub QQ114 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub QQ114 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub QQ114 then provides to the UE either directly, after performing local processing, and/or after adding additional local content. In still another example, the hub QQ114 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

The hub QQ114 may have a constant/persistent or intermittent connection to the network node QQ110b. The hub QQ114 may also allow for a different communication scheme and/or schedule between the hub QQ114 and UEs (e.g., UE QQ112c and/or QQ112d), and between the hub QQ114 and the core network QQ106. In other examples, the hub QQ114 is connected to the core network QQ106 and/or one or more UEs via a wired connection. Moreover, the hub QQ114 may be configured to connect to an M2M service provider over the access network QQ104 and/or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes QQ110 while still connected via the hub QQ114 via a wired or wireless connection. In some embodiments, the hub QQ114 may be a dedicated hub - that is, a hub whose primary function is to route communications to/from the UEs from/to the network node QQ110b. In other embodiments, the hub QQ114 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node QQ110b, but which is additionally capable of operating as a communication start and/or end point for certain data channels.

Figure 10 shows a UE QQ200 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged and/or operable to communicate wirelessly with network nodes and/or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless camera, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart device, wireless customer-premise equipment (CPE), vehicle, vehicle-mounted or vehicle embedded/integrated wireless device, etc. Other examples include any UE identified by the 3rd Generation Partnership Project (3GPP), including a narrow band internet of things (NB-loT) UE, a machine type communication (MTC) UE, and/or an enhanced MTC (eMTC) UE.

A UE may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to-everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and/or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

The UE QQ200 includes processing circuitry QQ202 that is operatively coupled via a bus QQ204 to an input/output interface QQ206, a power source QQ208, a memory QQ210, a communication interface QQ212, and/or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 10. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

The processing circuitry QQ202 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory QQ210. The processing circuitry QQ202 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry QQ202 may include multiple central processing units (CPUs). The processing circuitry QQ202 may be operable to provide, either alone or in conjunction with other UE QQ200 components, such as the memory QQ210, UE QQ200 functionality. For example, the processing circuitry QQ202 may be configured to cause the UE QQ202 to perform the methods as described with reference to Figure 2.

In the example, the input/output interface QQ206 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and/or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE QQ200. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

In some embodiments, the power source QQ208 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source QQ208 may further include power circuitry for delivering power from the power source QQ208 itself, and/or an external power source, to the various parts of the UE QQ200 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source QQ208. Power circuitry may perform any formatting, converting, or other modification to the power from the power source QQ208 to make the power suitable for the respective components of the UE QQ200 to which power is supplied.

The memory QQ210 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory QQ210 includes one or more application programs QQ214, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data QQ216. The memory QQ210 may store, for use by the UE QQ200, any of a variety of various operating systems or combinations of operating systems.

The memory QQ210 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and/or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUlCC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory QQ210 may allow the UE QQ200 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory QQ210, which may be or comprise a device-readable storage medium.

The processing circuitry QQ202 may be configured to communicate with an access network or other network using the communication interface QQ212. The communication interface QQ212 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna QQ222. The communication interface QQ212 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter QQ218 and/or a receiver QQ220 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter QQ218 and receiver QQ220 may be coupled to one or more antennas (e.g., antenna QQ222) and may share circuit components, software or firmware, or alternatively be implemented separately.

In some embodiments, communication functions of the communication interface QQ212 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented in according to one or more communication protocols and/or standards, such as IEEE 802.11 , Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol/internet protocol (TCP/IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface QQ212, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

As another example, a UE comprises an actuator, a motor, or a switch, related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or controls a robotic arm performing a medical procedure according to the received input.

A UE, when in the form of an Internet of Things (loT) device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are devices which are or which are embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door/window sensor, a flood/moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or Virtual Reality (VR), a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an loT device comprises circuitry and/or software in dependence on the intended application of the loT device in addition to other components as described in relation to the UE QQ200 shown in Figure 10.

As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another UE and/or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-loT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation.

In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and/or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.

Figure 11 shows a network node QQ300 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and/or operable to communicate directly or indirectly with a UE and/or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)), O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU).

Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O- RAN access node) and/or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

Other examples of network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell/multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and/or Minimization of Drive Tests (MDTs).

The network node QQ300 includes processing circuitry QQ302, a memory QQ304, a communication interface QQ306, and a power source QQ308, and/or any other component, or any combination thereof. The network node QQ300 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node QQ300 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node QQ300 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory QQ304 for different RATs) and some components may be reused (e.g., a same antenna QQ310 may be shared by different RATs). The network node QQ300 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node QQ300, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z- wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node QQ300.

The processing circuitry QQ302 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and/or encoded logic operable to provide, either alone or in conjunction with other network node QQ300 components, such as the memory QQ304, network node QQ300 functionality. For example, the processing circuitry QQ302 may be configured to cause the network node to perform the methods as described with reference to Figure 3 and/or W3.

In some embodiments, the processing circuitry QQ302 includes a system on a chip (SOC). In some embodiments, the processing circuitry QQ302 includes one or more of radio frequency (RF) transceiver circuitry QQ312 and baseband processing circuitry QQ314. In some embodiments, the radio frequency (RF) transceiver circuitry QQ312 and the baseband processing circuitry QQ314 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry QQ312 and baseband processing circuitry QQ314 may be on the same chip or set of chips, boards, or units.

The memory QQ304 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or any other volatile or non-volatile, non-transitory device-readable and/or computer-executable memory devices that store information, data, and/or instructions that may be used by the processing circuitry QQ302. The memory QQ304 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and/or other instructions capable of being executed by the processing circuitry QQ302 and utilized by the network node QQ300. The memory QQ304 may be used to store any calculations made by the processing circuitry QQ302 and/or any data received via the communication interface QQ306. In some embodiments, the processing circuitry QQ302 and memory QQ304 is integrated.

The communication interface QQ306 is used in wired or wireless communication of signaling and/or data between a network node, access network, and/or UE. As illustrated, the communication interface QQ306 comprises port(s)/terminal(s) QQ316 to send and receive data, for example to and from a network over a wired connection. The communication interface QQ306 also includes radio front-end circuitry QQ318 that may be coupled to, or in certain embodiments a part of, the antenna QQ310. Radio front-end circuitry QQ318 comprises filters QQ320 and amplifiers QQ322. The radio front-end circuitry QQ318 may be connected to an antenna QQ310 and processing circuitry QQ302. The radio front-end circuitry may be configured to condition signals communicated between antenna QQ310 and processing circuitry QQ302. The radio front-end circuitry QQ318 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry QQ318 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters QQ320 and/or amplifiers QQ322. The radio signal may then be transmitted via the antenna QQ310.

Similarly, when receiving data, the antenna QQ310 may collect radio signals which are then converted into digital data by the radio front-end circuitry QQ318. The digital data may be passed to the processing circuitry QQ302. In other embodiments, the communication interface may comprise different components and/or different combinations of components.

In certain alternative embodiments, the network node QQ300 does not include separate radio front-end circuitry QQ318, instead, the processing circuitry QQ302 includes radio frontend circuitry and is connected to the antenna QQ310. Similarly, in some embodiments, all or some of the RF transceiver circuitry QQ312 is part of the communication interface QQ306. In still other embodiments, the communication interface QQ306 includes one or more ports or terminals QQ316, the radio front-end circuitry QQ318, and the RF transceiver circuitry QQ312, as part of a radio unit (not shown), and the communication interface QQ306 communicates with the baseband processing circuitry QQ314, which is part of a digital unit (not shown).

The antenna QQ310 may include one or more antennas, or antenna arrays, configured to send and/or receive wireless signals. The antenna QQ310 may be coupled to the radio frontend circuitry QQ318 and may be any type of antenna capable of transmitting and receiving data and/or signals wirelessly. In certain embodiments, the antenna QQ310 is separate from the network node QQ300 and connectable to the network node QQ300 through an interface or port.

The antenna QQ310, communication interface QQ306, and/or the processing circuitry QQ302 may be configured to perform any receiving operations and/or certain obtaining operations described herein as being performed by the network node. Any information, data and/or signals may be received from a UE, another network node and/or any other network equipment. Similarly, the antenna QQ310, the communication interface QQ306, and/or the processing circuitry QQ302 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and/or signals may be transmitted to a UE, another network node and/or any other network equipment.

The power source QQ308 provides power to the various components of network node QQ300 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source QQ308 may further comprise, or be coupled to, power management circuitry to supply the components of the network node QQ300 with power for performing the functionality described herein. For example, the network node QQ300 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source QQ308. As a further example, the power source QQ308 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

Embodiments of the network node QQ300 may include additional components beyond those shown in Figure 11 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and/or any functionality necessary to support the subject matter described herein. For example, the network node QQ300 may include user interface equipment to allow input of information into the network node QQ300 and to allow output of information from the network node QQ300. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node QQ300.

Figure 15 shows a network node QQ700 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and/or operable to communicate directly or indirectly with a UE and/or with other network nodes or equipment, in a telecommunication network. The network node QQ700 may be operable as a core network node, a core network function or, more generally, a core network entity, such as the core network node QQ108 described above with respect to Figure 9). Examples of network nodes in this context include core network entities such as one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), Policy Control Function (PCF) and/or a User Plane Function (UPF).

The network node QQ700 includes processing circuitry QQ702, a memory QQ704, a communication interface QQ706, and a power source QQ708, and/or any other component, or any combination thereof. The network node QQ700 may be composed of multiple physically separate components, which may each have their own respective components. In certain scenarios in which the network node QQ700 comprises multiple separate components, one or more of the separate components may be shared among several network nodes.

The processing circuitry QQ702 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and/or encoded logic operable to provide, either alone or in conjunction with other network node QQ700 components, such as the memory QQ704, network node QQ700 functionality.

The memory QQ704 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or any other volatile or non-volatile, non-transitory device-readable and/or computer-executable memory devices that store information, data, and/or instructions that may be used by the processing circuitry QQ702. The memory QQ704 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and/or other instructions capable of being executed by the processing circuitry QQ702 and utilized by the network node QQ700. The memory QQ704 may be used to store any calculations made by the processing circuitry QQ702 and/or any data received via the communication interface QQ706. In some embodiments, the processing circuitry QQ702 and memory QQ704 is integrated.

The communication interface QQ706 is used in wired or wireless communication of signaling and/or data between a network node, access network, and/or UE.

The power source QQ708 provides power to the various components of network node QQ700 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source QQ708 may further comprise, or be coupled to, power management circuitry to supply the components of the network node QQ700 with power for performing the functionality described herein. For example, the network node QQ700 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source QQ708. As a further example, the power source QQ708 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

Embodiments of the network node QQ700 may include additional components beyond those shown in Figure 15 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and/or any functionality necessary to support the subject matter described herein. For example, the network node QQ700 may include user interface equipment to allow input of information into the network node QQ700 and to allow output of information from the network node QQ700. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node QQ700.

Figure 12 is a block diagram of a host QQ400, which may be an embodiment of the host QQ116 of Figure 9, in accordance with various aspects described herein. As used herein, the host QQ400 may be or comprise various combinations hardware and/or software, including a standalone server, a blade server, a cloud-implemented server, a distributed server, a virtual machine, container, or processing resources in a server farm. The host QQ400 may provide one or more services to one or more UEs.

The host QQ400 includes processing circuitry QQ402 that is operatively coupled via a bus QQ404 to an input/output interface QQ406, a network interface QQ408, a power source QQ410, and a memory QQ412. Other components may be included in other embodiments. Features of these components may be substantially similar to those described with respect to the devices of previous figures, such as Figures 10 and 11 , such that the descriptions thereof are generally applicable to the corresponding components of host QQ400.

The memory QQ412 may include one or more computer programs including one or more host application programs QQ414 and data QQ416, which may include user data, e.g., data generated by a UE for the host QQ400 or data generated by the host QQ400 for a UE. Embodiments of the host QQ400 may utilize only a subset or all of the components shown. The host application programs QQ414 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (WC), High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), MPEG, VP9) and audio codecs (e.g., FLAC, Advanced Audio Coding (AAC), MPEG, G.711), including transcoding for multiple different classes, types, or implementations of UEs (e.g., handsets, desktop computers, wearable display systems, heads-up display systems). The host application programs QQ414 may also provide for user authentication and licensing checks and may periodically report health, routes, and content availability to a central node, such as a device in or on the edge of a core network. Accordingly, the host QQ400 may select and/or indicate a different host for over-the-top services for a UE. The host application programs QQ414 may support various protocols, such as the HTTP Live Streaming (HLS) protocol, Real-Time Messaging Protocol (RTMP), Real-Time Streaming Protocol (RTSP), Dynamic Adaptive Streaming over HTTP (MPEG-DASH), etc.

Figure 13 is a block diagram illustrating a virtualization environment QQ500 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments QQ500 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment QQ500 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an 0-2 interface.

Applications QQ502 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and/or benefits of some of the embodiments disclosed herein.

Hardware QQ504 includes processing circuitry, memory that stores software and/or instructions executable by hardware processing circuitry, and/or other hardware devices as described herein, such as a network interface, input/output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers QQ506 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs QQ508a and QQ508b (one or more of which may be generally referred to as VMs QQ508), and/or perform any of the functions, features and/or benefits described in relation with some embodiments described herein. The virtualization layer QQ506 may present a virtual operating platform that appears like networking hardware to the VMs QQ508. The VMs QQ508 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer QQ506. Different embodiments of the instance of a virtual appliance QQ502 may be implemented on one or more of VMs QQ508, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

In the context of NFV, a VM QQ508 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs QQ508, and that part of hardware QQ504 that executes that VM, be it hardware dedicated to that VM and/or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs QQ508 on top of the hardware QQ504 and corresponds to the application QQ502.

Hardware QQ504 may be implemented in a standalone network node with generic or specific components. Hardware QQ504 may implement some functions via virtualization. Alternatively, hardware QQ504 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration QQ510, which, among others, oversees lifecycle management of applications QQ502. In some embodiments, hardware QQ504 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system QQ512 which may alternatively be used for communication between hardware nodes and radio units.

Figure 14 shows a communication diagram of a host QQ602 communicating via a network node QQ604 with a UE QQ606 over a partially wireless connection in accordance with some embodiments. Example implementations, in accordance with various embodiments, of the UE (such as a UE QQ112a of Figure 9 and/or UE QQ200 of Figure 10), network node (such as network node QQ110a of Figure 9 and/or network node QQ300 of Figure 11), and host (such as host QQ116 of Figure 9 and/or host QQ400 of Figure 12) discussed in the preceding paragraphs will now be described with reference to Figure 14. Like host QQ400, embodiments of host QQ602 include hardware, such as a communication interface, processing circuitry, and memory. The host QQ602 also includes software, which is stored in or accessible by the host QQ602 and executable by the processing circuitry. The software includes a host application that may be operable to provide a service to a remote user, such as the UE QQ606 connecting via an over-the-top (OTT) connection QQ650 extending between the UE QQ606 and host QQ602. In providing the service to the remote user, a host application may provide user data which is transmitted using the OTT connection QQ650.

The network node QQ604 includes hardware enabling it to communicate with the host QQ602 and UE QQ606. The connection QQ660 may be direct or pass through a core network (like core network QQ106 of Figure 9) and/or one or more other intermediate networks, such as one or more public, private, or hosted networks. For example, an intermediate network may be a backbone network or the Internet.

The UE QQ606 includes hardware and software, which is stored in or accessible by UE QQ606 and executable by the UE’s processing circuitry. The software includes a client application, such as a web browser or operator-specific “app” that may be operable to provide a service to a human or non-human user via UE QQ606 with the support of the host QQ602. In the host QQ602, an executing host application may communicate with the executing client application via the OTT connection QQ650 terminating at the UE QQ606 and host QQ602. In providing the service to the user, the UE's client application may receive request data from the host's host application and provide user data in response to the request data. The OTT connection QQ650 may transfer both the request data and the user data. The UE's client application may interact with the user to generate the user data that it provides to the host application through the OTT connection QQ650.

The OTT connection QQ650 may extend via a connection QQ660 between the host QQ602 and the network node QQ604 and via a wireless connection QQ670 between the network node QQ604 and the UE QQ606 to provide the connection between the host QQ602 and the UE QQ606. The connection QQ660 and wireless connection QQ670, over which the OTT connection QQ650 may be provided, have been drawn abstractly to illustrate the communication between the host QQ602 and the UE QQ606 via the network node QQ604, without explicit reference to any intermediary devices and the precise routing of messages via these devices.

As an example of transmitting data via the OTT connection QQ650, in step QQ608, the host QQ602 provides user data, which may be performed by executing a host application. In some embodiments, the user data is associated with a particular human user interacting with the UE QQ606. In other embodiments, the user data is associated with a UE QQ606 that shares data with the host QQ602 without explicit human interaction. In step QQ610, the host QQ602 initiates a transmission carrying the user data towards the UE QQ606. The host QQ602 may initiate the transmission responsive to a request transmitted by the UE QQ606. The request may be caused by human interaction with the UE QQ606 or by operation of the client application executing on the UE QQ606. The transmission may pass via the network node QQ604, in accordance with the teachings of the embodiments described throughout this disclosure. Accordingly, in step QQ612, the network node QQ604 transmits to the UE QQ606 the user data that was carried in the transmission that the host QQ602 initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step QQ614, the UE QQ606 receives the user data carried in the transmission, which may be performed by a client application executed on the UE QQ606 associated with the host application executed by the host QQ602.

In some examples, the UE QQ606 executes a client application which provides user data to the host QQ602. The user data may be provided in reaction or response to the data received from the host QQ602. Accordingly, in step QQ616, the UE QQ606 may provide user data, which may be performed by executing the client application. In providing the user data, the client application may further consider user input received from the user via an input/output interface of the UE QQ606. Regardless of the specific manner in which the user data was provided, the UE QQ606 initiates, in step QQ618, transmission of the user data towards the host QQ602 via the network node QQ604. In step QQ620, in accordance with the teachings of the embodiments described throughout this disclosure, the network node QQ604 receives user data from the UE QQ606 and initiates transmission of the received user data towards the host QQ602. In step QQ622, the host QQ602 receives the user data carried in the transmission initiated by the UE QQ606.

One or more of the various embodiments improve the performance of OTT services provided to the UE QQ606 using the OTT connection QQ650, in which the wireless connection QQ670 forms the last segment. More precisely, the teachings of these embodiments may provide benefits such as, for example, ensuring that the network is aware that the received LTM configuration is applied on the configuration the UE uses in the target cell, and not in the source cell.

In an example scenario, factory status information may be collected and analyzed by the host QQ602. As another example, the host QQ602 may process audio and video data which may have been retrieved from a UE for use in creating maps. As another example, the host QQ602 may collect and analyze real-time data to assist in controlling vehicle congestion (e.g., controlling traffic lights). As another example, the host QQ602 may store surveillance video uploaded by a UE. As another example, the host QQ602 may store or control access to media content such as video, audio, VR or AR which it can broadcast, multicast or unicast to UEs. As other examples, the host QQ602 may be used for energy pricing, remote control of non-time critical electrical load to balance power generation needs, location services, presentation services (such as compiling diagrams etc. from data collected from remote devices), or any other function of collecting, retrieving, storing, analyzing and/or transmitting data.

In some examples, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection QQ650 between the host QQ602 and UE QQ606, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection may be implemented in software and hardware of the host QQ602 and/or UE QQ606. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which the OTT connection QQ650 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software may compute or estimate the monitored quantities. The reconfiguring of the OTT connection QQ650 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not directly alter the operation of the network node QQ604. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling that facilitates measurements of throughput, propagation times, latency and the like, by the host QQ602. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection QQ650 while monitoring propagation times, errors, etc.

This disclosure includes the following enumerated embodiments.

EMBODIMENTS

Group A Embodiments

1 . A method performed by a User Equipment (UE) for performing a cell switch procedure, the method comprising: receiving one or more L1/L2-triggered mobility (LTM) candidate target cell configurations; receiving a LTM cell switch command identifying one of the one or more LTM candidate target cell configurations; applying the identified LTM candidate target cell configuration to switch to a target cell; and sending signalling on the target cell to indicate that the identified LTM candidate target cell configuration has been applied.

2. The method of embodiment 1 , wherein the signalling on the target cell indicates that the cell switch procedure is complete.

3. The method of embodiment 1 or 2, comprising generating or preparing the signalling in response to receiving the one or more LTM target cell configurations.

4. The method of embodiment 3, wherein the identified LTM candidate target cell configuration includes or is associated with an instruction to generate or prepare the signalling.

5. The method of embodiment 3 or 4, comprising generating or preparing respective signalling for each of the one or more LTM target cell configurations in response to receiving the one or more LTM target cell configurations.

6. The method of embodiment 1 or 2, comprising generating or preparing the signalling in response to receiving the LTM cell switch command.

7. The method of embodiment 1 or 2, comprising generating or preparing the signalling after applying the identified LTM target cell configuration.

8. The method of any of embodiments 1 , 2 or 7, comprising generating or preparing the signalling after the UE has synchronized with the target cell.

9. The method of embodiment 7 or 8, comprising generating or preparing the signalling in response to an indication from a MAC layer, a Layer 2 (L2) layer, a RRC layer and/or a Layer 3 (L3) layer.

10. The method of embodiment 9, wherein the indication indicates that the identified LTM target cell configuration has been applied and/or the UE has synchronized with the target cell. 11. The method of embodiment 1 or 2, comprising performing a random access procedure on the target cell after applying the identified LTM candidate target cell configuration.

12. The method of embodiment 11 , comprising generating or preparing the signalling in response to completion of the random access procedure and/or in response to receiving, on the target cell, a random access response and/or contention resolution information.

13. The method of embodiment 11 or 12, comprising sending the signalling in response to completion of the random access procedure and/or in response to receiving, on the target cell, a random access response and/or contention resolution information.

14. The method of embodiment 1 or 2, wherein the identified LTM candidate target cell configuration includes or identifies the signaling.

15. The method of any of embodiments 1 to 14, comprising generating a complete LTM target cell configuration based on the identified target cell configuration and a reference configuration.

16. The method of embodiment 15, wherein applying the identified LTM candidate target cell configuration comprises applying the complete LTM target cell configuration.

17. The method of embodiment 15 or 16, comprising generating a respective complete LTM target cell configuration for each of the one or more LTM target cell configurations based on the LTM target cell configuration and the reference configuration.

18. The method of any of embodiments 1 to 17, wherein the signalling comprises one or more RRC messages and/or one or more RRCReconfigurationComplete messages and/or one or more MAC Control Elements (CEs) and/or Layer 1 (L1) signalling.

19. The method of any of embodiments 1 to 18, wherein sending the signalling on the target cell is performed in response to the identified LTM candidate target cell configuration including or being associated with an indication to send the signalling on the target cell. 20. The method of any of embodiments 1 to 18, wherein sending the signalling on the target cell is performed in response to a serving cell of the UE and the target cell being in a same set of cells.

21. The method of embodiment 20, comprising receiving information identifying the set of cells.

22. The method of embodiment 21 , wherein the information identifying the set of cells is received on the serving cell and/or from a network node, gNB, Distributed Unit (DU) or Central Unit (CU).

23. The method of any of embodiments 1 to 22, comprising, in response to receiving the one or more LTM candidate target cell configurations: sending signalling on a serving cell and/or the target cell to indicate that the identified LTM candidate target cell configuration has been received and/or decoded and/or applied; or sending, for each of the one or more LTM candidate target cell configurations, signalling on the serving cell and/or a respective target cell associated with the LTM target cell configuration to indicate that the LTM candidate target cell configuration has been received and/or decoded and/or applied.

24. The method of embodiment 1 to 23, wherein sending the signalling on the target cell is performed only for a first time the UE applies the identified LTM candidate target cell configuration.

25. The method of any of embodiments 1 to 24, wherein the one or more L1/L2-triggered mobility (LTM) candidate target cell configurations and/or the receiving a LTM cell switch command are received from a serving cell and/or a network node associated with the serving cell.

26. The method of embodiment 25, wherein the network node associated with the serving cell comprises a gNB, DU or CU.

27. The method of any of embodiments 1 to 26, wherein sending the signalling on the target cell comprises sending the signalling to a network node associated with the target cell. 28. The method of embodiment 27, wherein the network node associated with the target cell comprises a gNB, DU or CU.

29. The method of any of embodiments 1 to 28, wherein performing the cell switch procedure comprises applying the identified LTM candidate target cell configuration.

30. The method of any of embodiments 1 to 29, wherein applying the identified LTM candidate target cell configuration comprises executing the identified candidate target cell configuration.

31. The method of any of embodiments 1 to 30, wherein applying the identified candidate target cell configuration is performed by a RRC layer.

32. The method of embodiment 31 , wherein the RRC layer applies the identified candidate target cell configuration in response to an indication from a layer lower than the RRC layer.

33. The method of embodiment 32, wherein the indication from the layer lower than the RRC layer identifies the identified LTM candidate target cell configuration.

34. The method of any of embodiments 31 to 33, wherein the RRC layer sends an indication to the layer lower than the RRC layer after applying the identified candidate target cell configuration.

35. The method of any of 1 to 31 , wherein the identified LTM candidate target cell configuration or each of the one or more LTM candidate target cell configurations comprises one or more of:

• A cell group configuration for a Master Cell Group (MCG) or a Secondary Cell Group (SCG);

• A serving cell configuration for a SpCell, PCell, PSCell or SCell;

• A bandwidth Part (BWP) configuration;

• An RRCReconfiguration message;

• A measurement configuration;

• A radio bearer configuration;

• A UE identity or C-RNTI; • System information;

• A timer configuration;

• Another candidate cell configuration;

• An indication for the UE to perform a full configuration;

• An indication for the UE to perform a delta configuration;

• A reference configuration; and/or

• Indication(s) whether or not to perform L2 reset, MAC reset, partial MAC reset, full MAC reset, RLC re-establishment and/or PDCP recovery or reestablishment.

36. The method of any of the previous embodiments, further comprising: providing user data; and forwarding the user data to a host via the transmission to the network node.

Group B Embodiments

37. A method performed by a network node for causing a User Equipment (UE) to perform a cell switch procedure, wherein the network node is associated with a serving cell of the UE, the method comprising: sending, to the UE, one or more L1/L2-triggered mobility (LTM) candidate target cell configurations; and receiving, from the UE, signalling to indicate that the identified LTM candidate target cell configuration has been received and/or decoded and/or applied.

38. The method of embodiment 37, comprising sending, to the UE, a LTM cell switch command identifying one of the one or more LTM candidate target cell configurations.

39. The method of embodiment 38, wherein the signalling is received from the UE after sending the LTM cell switch command to the UE.

40. The method of any of embodiments 37 to 39, wherein receiving, from the UE, signalling to indicate that the identified LTM candidate target cell configuration has been received and/or decoded and/or applied comprises receiving, from the UE, for each of the one or more LTM candidate target cell configurations, signalling on the serving cell and/or a respective target cell associated with the LTM target cell configuration to indicate that the LTM candidate target cell configuration has been received and/or decoded and/or applied. 41 . The method of any of embodiments 37 to 40, wherein the signalling comprises one or more RRC messages and/or one or more RRCReconfigurationComplete messages and/or one or more MAC Control Elements (CEs) and/or Layer 1 (L1) signalling.

42. The method of any of embodiments 37 to 41 , wherein the network node comprises a gNB, DU or CU.

43. A method performed by a network node, wherein the network node is associated with a target cell of a L1/L2-triggered mobility (LTM) candidate target cell configuration for a LTM cell switch procedure by a User Equipment (UE), the method comprising: receiving, from a User Equipment (UE), signalling to indicate that the LTM candidate target cell configuration has been received and/or decoded and/or applied.

44. The method of embodiment 43, wherein the signalling indicates that the cell switch procedure is complete.

45. The method of embodiment 43 or 44, comprising receiving the signalling after the UE has synchronized with the target cell.

46. The method of any of embodiments 43 to 45, wherein the signalling comprises one or more RRC messages and/or one or more RRCReconfigurationComplete messages and/or one or more MAC Control Elements (CEs) and/or Layer 1 (L1) signalling.

47. The method of any of embodiments 43 to 46, comprising receiving the signalling in response to the LTM candidate target cell configuration including or being associated with an indication to send the signalling on the target cell.

48. The method of any of embodiments 43 to 47, comprising receiving the signalling in response to a serving cell of the UE and the target cell being in a same set of cells.

49. The method of any of embodiments 43 to 48, wherein the network node comprises a gNB, DU or CU.

50. The method of any of embodiments 43 to 48, wherein the network node comprises a DU, and the method comprises sending the signalling to a CU.

51 . The method of any of embodiments 43 to 48, wherein the network node comprises a CU, and the method comprises receiving the signalling via a DU. 52. The method of embodiment 51 , comprising sending, to a network node associated with a previous serving cell of the UE, the signalling and/or an indication that the cell switch procedure by the UE is complete and/or an indication that the LTM candidate target cell configuration has been applied by the UE.

53. The method of any of the previous embodiments, further comprising: obtaining user data; and forwarding the user data to a host or a user equipment.

Group D Embodiments

54. A user equipment for performing a cell switch procedure, comprising: processing circuitry configured to cause the user equipment to perform any of the steps of any of the Group A embodiments; and power supply circuitry configured to supply power to the processing circuitry.

55. A network node, the network node comprising: processing circuitry configured to cause the network node to perform any of the steps of any of the Group B embodiments; power supply circuitry configured to supply power to the processing circuitry.

56. A user equipment (UE) for performing a cell switch procedure, the UE comprising: an antenna configured to send and receive wireless signals; radio front-end circuitry connected to the antenna and to processing circuitry, and configured to condition signals communicated between the antenna and the processing circuitry; the processing circuitry being configured to perform any of the steps of any of the Group A embodiments; an input interface connected to the processing circuitry and configured to allow input of information into the UE to be processed by the processing circuitry; an output interface connected to the processing circuitry and configured to output information from the UE that has been processed by the processing circuitry; and a battery connected to the processing circuitry and configured to supply power to the UE.

57. A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising: processing circuitry configured to provide user data; and a network interface configured to initiate transmission of the user data to a network node in a cellular network for transmission to a user equipment (UE), the network node having a communication interface and processing circuitry, the processing circuitry of the network node configured to perform any of the operations of any of the Group B embodiments to transmit the user data from the host to the UE.

58. The host of the previous embodiment, wherein: the processing circuitry of the host is configured to execute a host application that provides the user data; and the UE comprises processing circuitry configured to execute a client application associated with the host application to receive the transmission of user data from the host.

59. A method implemented in a host configured to operate in a communication system that further includes a network node and a user equipment (UE), the method comprising: providing user data for the UE; and initiating a transmission carrying the user data to the UE via a cellular network comprising the network node, wherein the network node performs any of the operations of any of the Group B embodiments to transmit the user data from the host to the UE.

60. The method of the previous embodiment, further comprising, at the network node, transmitting the user data provided by the host for the UE.

61. The method of any of the previous 2 embodiments, wherein the user data is provided at the host by executing a host application that interacts with a client application executing on the UE, the client application being associated with the host application.

62. A communication system configured to provide an over-the-top (OTT) service, the communication system comprising: a host comprising: processing circuitry configured to provide user data for a user equipment (UE), the user data being associated with the over-the-top service; and a network interface configured to initiate transmission of the user data toward a cellular network node for transmission to the UE, the network node having a communication interface and processing circuitry, the processing circuitry of the network node configured to perform any of the operations of any of the Group B embodiments to transmit the user data from the host to the UE.

63. The communication system of the previous embodiment, further comprising: the network node; and/or the UE.

64. A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising: processing circuitry configured to initiate receipt of user data; and a network interface configured to receive the user data from a network node in a cellular network, the network node having a communication interface and processing circuitry, the processing circuitry of the network node configured to perform any of the operations of any of the Group B embodiments to receive the user data from a user equipment (UE) for the host.

65. The host of the previous 2 embodiments, wherein: the processing circuitry of the host is configured to execute a host application that receives the user data; and the host application is configured to interact with a client application executing on the UE, the client application being associated with the host application.

66. The host of the any of the previous 2 embodiments, wherein the initiating receipt of the user data comprises requesting the user data.

67. A method implemented by a host configured to operate in a communication system that further includes a network node and a user equipment (UE), the method comprising: at the host, initiating receipt of user data from the UE, the user data originating from a transmission which the network node has received from the UE, wherein the network node performs any of the steps of any of the Group B embodiments to receive the user data from the UE for the host.

68. The method of the previous embodiment, further comprising at the network node, transmitting the received user data to the host. 69. A host configured to operate in a communication system to provide an over-the-top

(OTT) service, the host comprising: processing circuitry configured to provide user data; and a network interface configured to initiate transmission of the user data to a cellular network for transmission to a user equipment (UE), wherein the UE comprises a communication interface and processing circuitry, the communication interface and processing circuitry of the UE being configured to perform any of the operations of any of the Group A embodiments to receive the user data from the host.

70. The host of the previous embodiment, wherein the cellular network further includes a network node configured to communicate with the UE to transmit the user data to the UE from the host.

71. The host of the previous 2 embodiments, wherein: the processing circuitry of the host is configured to execute a host application, thereby providing the user data; and the host application is configured to interact with a client application executing on the UE, the client application being associated with the host application.

72. A method implemented by a host operating in a communication system that further includes a network node and a user equipment (UE), the method comprising: providing user data for the UE; and initiating a transmission carrying the user data to the UE via a cellular network comprising the network node, wherein the UE performs any of the operations of any of the Group A embodiments to receive the user data from the host.

73. The method of the previous embodiment, further comprising: at the host, executing a host application associated with a client application executing on the UE to receive the user data from the host application.

74. The method of the previous embodiment, further comprising: at the host, transmitting input data to the client application executing on the UE, the input data being provided by executing the host application, wherein the user data is provided by the client application in response to the input data from the host application. 75. A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising: processing circuitry configured to provide user data; and a network interface configured to initiate transmission of the user data to a cellular network for transmission to a user equipment (UE), wherein the UE comprises a communication interface and processing circuitry, the communication interface and processing circuitry of the UE being configured to perform any of the steps of any of the Group A embodiments to transmit the user data to the host.

76. The host of the previous embodiment, wherein the cellular network further includes a network node configured to communicate with the UE to transmit the user data from the UE to the host.

77. The host of the previous 2 embodiments, wherein: the processing circuitry of the host is configured to execute a host application, thereby providing the user data; and the host application is configured to interact with a client application executing on the UE, the client application being associated with the host application.

78. A method implemented by a host configured to operate in a communication system that further includes a network node and a user equipment (UE), the method comprising: at the host, receiving user data transmitted to the host via the network node by the UE, wherein the UE performs any of the steps of any of the Group A embodiments to transmit the user data to the host.

79. The method of the previous embodiment, further comprising: at the host, executing a host application associated with a client application executing on the UE to receive the user data from the UE.

Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and/or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and/or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and/or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer- readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer- readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and/or by end users and a wireless network generally.

Claims

1. A method performed by a User Equipment, UE, for performing a Layer 1/Layer 2 Triggered Mobility, LTM, cell switch procedure, the method comprising: receiving one or more LTM candidate cell configurations; receiving a LTM cell switch command including an indication of one of the one or more LTM candidate cell configurations; applying the indicated LTM candidate cell configuration to switch to a cell associated with the indicated LTM candidate cell configuration; and in response to applying the indicated LTM candidate cell configuration, sending signalling on the cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

2. The method of claim 1 , comprising generating or preparing the signalling in response to receiving the LTM cell switch command, after applying the indicated LTM candidate cell configuration, after the UE has synchronized with the cell associated with the indicated LTM candidate cell configuration, or in response to an indication from a MAC layer.

3. The method of claim 2, wherein the indication from the MAC layer indicates that the indicated LTM candidate cell configuration has been applied and/or the UE has synchronized with the cell associated with the indicated LTM candidate cell configuration.

4. The method of claim 1 , comprising performing a random access procedure on the cell after applying the indicated LTM candidate cell configuration.

5. The method of claim 4, comprising sending the signalling after completion of the random access procedure and/or after receiving, on the cell associated with the indicated LTM candidate cell configuration, a random access response and/or contention resolution information.

6. The method of any of claims 1 to 5, comprising generating a complete LTM candidate cell configuration based on the indicated LTM cell configuration and a reference configuration.

7. The method of claim 6, wherein applying the indicated LTM candidate cell configuration comprises applying the complete LTM candidate cell configuration.

8. The method of any of claims 1 to 7, wherein the signalling comprises one or more RRC messages and/or one or more RRCReconfigurationComplete messages and/or one or more MAC Control Elements, CEs, and/or Layer 1 , L1 , signalling.

9. The method of any of claims 1 to 8, comprising, in response to receiving the one or more LTM candidate cell configurations: sending signalling on a serving cell and/or the cell associated with the indicated LTM candidate cell configuration to indicate that the indicated LTM candidate cell configuration has been received and/or decoded and/or applied; or sending, for each of the one or more LTM candidate cell configurations, signalling on the serving cell and/or a respective cell associated with the LTM candidate cell configuration to indicate that the LTM candidate cell configuration has been received and/or decoded and/or applied.

10. The method of any of claims 1 to 9, wherein the one or more LTM candidate cell configurations and/or the LTM cell switch command are received from a serving cell and/or a network node associated with the serving cell.

11 . The method of any of claims 1 to 10, wherein sending the signalling on the cell associated with the indicated LTM candidate cell configuration comprises sending the signalling to a network node associated with the cell associated with the indicated LTM candidate cell configuration.

12. The method of any of claims 1 to 11 , wherein applying the indicated LTM candidate cell configuration is performed by a RRC layer.

13. The method of claim 12, wherein the RRC layer applies the indicated LTM candidate cell configuration in response to an indication from a layer lower than the RRC layer.

14. The method of claim 13, wherein the indication from the layer lower than the RRC layer identifies the indicated LTM candidate cell configuration.

15. The method of any of claims 12 to 14, wherein the RRC layer sends an indication to the layer lower than the RRC layer after applying the indicated LTM candidate cell configuration.

16. The method of any of claims 1 to 15, wherein the indicated LTM candidate cell configuration or each of the one or more LTM candidate cell configurations comprises one or more of:

• A serving cell configuration for a SpCell, PCell, PSCell or SCell;

• A bandwidth Part, BWP configuration;

• An RRCReconfiguration message;

• A measurement configuration;

• A radio bearer configuration;

• A UE identity or C-RNTI;

• System information;

• A timer configuration;

• Another candidate cell configuration;

• An indication for the UE to perform a full configuration;

• An indication for the UE to perform a delta configuration;

• A reference configuration; and/or

17. A method performed by a network node for causing a User Equipment, UE, to perform a Layer 1/Layer 2 Triggered Mobility, LTM, cell switch procedure, wherein the network node is associated with a serving cell of the UE, the method comprising: sending, to the UE, one or more LTM candidate cell configurations; sending, to the UE, a LTM cell switch command including an indication of one of the one or more LTM candidate target cell configurations; and receiving signalling from the UE on a cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

18. The method of claim 17, wherein the signalling comprises one or more RRC messages and/or one or more RRCReconfigurationComplete messages and/or one or more MAC Control Elements, CEs, and/or Layer 1 , L1 , signalling.

19. A method performed by a network node, wherein the network node is associated with a cell associated with a L1/L2-triggered mobility, LTM, candidate cell configuration for a LTM cell switch procedure by a User Equipment, UE, the method comprising: receiving signalling from the UE on the cell associated with the LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

20. The method of claim 19, comprising receiving the signalling after the UE has synchronized with the cell associated with the LTM candidate cell configuration.

21 . The method of claim 19 or 20, wherein the signalling comprises one or more RRC messages and/or one or more RRCReconfigurationComplete messages and/or one or more MAC Control Elements, CEs, and/or Layer 1 , L1 , signalling.

22. The method of any of claims 19 to 21 , comprising receiving the signalling in response to the LTM candidate cell configuration including or being associated with an indication to send the signalling on the cell.

23. A computer program comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out a method according to any of claims 1 to 22.

24. A carrier containing a computer program according to claim 23, wherein the carrier comprises one of an electronic signal, optical signal, radio signal or computer readable storage medium.

25. A computer program product comprising non transitory computer readable media having stored thereon a computer program according to claim 23.

26. Apparatus in a User Equipment, UE, for performing a Layer 1 /Layer 2 Triggered Mobility, LTM, cell switch procedure, the apparatus comprising a processor and a memory, the memory containing instructions executable by the processor such that the apparatus is operable to: receive one or more LTM candidate target cell configurations; receive a LTM cell switch command including an indication of one of the one or more LTM candidate cell configurations; apply the indicated LTM candidate cell configuration to switch to a cell associated with the indicated LTM candidate cell configuration; and in response to applying the indicated LTM candidate cell configuration, send signalling on the cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

27. The apparatus of claim 26, wherein the memory contains instructions executable by the processor such that the apparatus is operable to perform the method of any of claims 2 to 16.

28. Apparatus in a network node for causing a User Equipment, UE, to perform a Layer 1/Layer 2 Triggered Mobility, LTM, cell switch procedure, wherein the network node is associated with a serving cell of the UE, the apparatus comprising a processor and a memory, the memory containing instructions executable by the processor such that the apparatus is operable to: send, to the UE, one or more LTM candidate target cell configurations; send, to the UE, a LTM cell switch command including an indication of one of the one or more LTM candidate target cell configurations; and receive signalling from the UE on a cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

29. The apparatus of claim 28, wherein the memory contains instructions executable by the processor such that the apparatus is operable to perform the method of claim 18.

30. Apparatus in a network node, wherein the network node is associated with a cell associated with a L1/L2-triggered mobility, LTM, candidate cell configuration for a LTM cell switch procedure by a User Equipment, UE, the apparatus comprising a processor and a memory, the memory containing instructions executable by the processor such that the apparatus is operable to: receive signalling from the UE on the cell associated with the LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

31 . The apparatus of claim 30, wherein the memory contains instructions executable by the processor such that the apparatus is operable to perform the method of any of claims 20 to 22.

32. Apparatus in a User Equipment, UE, for performing a Layer 1 /Layer 2 Triggered Mobility, LTM, cell switch procedure, the apparatus configured to: receive one or more LTM candidate target cell configurations; receive a LTM cell switch command including an indication of one of the one or more LTM candidate cell configurations; apply the indicated LTM candidate cell configuration to switch to a cell associated with the indicated LTM candidate cell configuration; and in response to applying the indicated LTM candidate cell configuration, send signalling on the cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

33. The apparatus of claim 32, wherein the apparatus is configured to perform the method of any of claims 2 to 16.

34. Apparatus in a network node for causing a User Equipment, UE, to perform a Layer 1/Layer 2 Triggered Mobility, LTM, cell switch procedure, wherein the network node is associated with a serving cell of the UE, the apparatus configured to: send, to the UE, one or more LTM candidate target cell configurations; send, to the UE, a LTM cell switch command including an indication of one of the one or more LTM candidate target cell configurations; and receive signalling from the UE on a cell associated with the indicated LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

35. The apparatus of claim 34, wherein the apparatus is configured to perform the method of claim 18.

36. Apparatus in a network node, wherein the network node is associated with a cell associated with a L1/L2-triggered mobility, LTM, candidate cell configuration for a LTM cell switch procedure by a User Equipment, UE, the apparatus configured to: receive signalling from the UE on the cell associated with the LTM candidate cell configuration, wherein the signalling indicates that the cell switch procedure is complete.

37. The apparatus of claim 36, wherein the apparatus is configured to perform the method of any of claims 20 to 22.