Configuration for lower-layer cell mobility procedures

Abstract

A method is performed by a user equipment The method comprises receiving (502), from a network node, a configuration for use in connecting to and / or communicating with a candidate cell following a lower-layer cell mobility procedure. The configuration comprises information that enables the user equipment to refresh one or more security keys for use in connecting to and / or communicating with the candidate cell. [Figure 8 to accompany the abstract.]

Description

CONFIGURATION FOR LOWER-LAYER CELL MOBILITY PROCEDURESTECHNICAL FIELD[0] Embodiments of the present disclosure relate to communications networks, and particularly to configurations for lower-layer cell mobility procedures.BACKGROUNDLayer 1 (Ll) / Layer 2 (L2) based inter-cell mobility in Release 18 (Rel-18)[1] In 3rd Generation Partnership Project (3GPP) Release 18, a work item known as Further New Radio (NR) mobility enhancements is ongoing. This work item includes a technical area entitled L1 / L2 based inter-cell mobility. According to the MediaTek Inc and Apple 3GPP Work Item Description entitled “Further NR mobility enhancements” (RP -223520), when the User Equipment (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 Layer 3 (L3) measurements and is done by Radio Resource Control (RRC) signalling triggered Reconfiguration with Synchronisation for change of Primary Cell (PCell) and Primary Secondary Cell (PSCell), as well as release / add for Secondary Cells (SCells) when applicable. All cases involve complete L2 (and LI) 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.[2] According to the WID, the following is included as one objective of the work:To specify mechanism and procedures of L1 / L2 based inter-cell mobility for mobility latency reduction:• Configuration and maintenance for multiple candidate cells to allow fast application of configurations for candidate cells [RAN2, RAN3]• Dynamic switch mechanism among candidate serving cells (including SpCell and SCell) for the potential applicable scenarios based on L1 / L2 signalling [RAN2, RANI]• LI enhancements for inter-cell beam management, including LI measurement and reporting, and beam indication [RANI, RAN2]Note 1: Early RAN 2 involvement is necessary, including the possibility of further clarifying the interaction between this bullet with the previous bulletTiming Advance management [RANI, RAN2]Central Unit (CU) - Distributed Unit (DU) interface signaling to support L1 / L2 mobility, if needed [RAN3]Note 2: Frequency Range 2 (FR2) specific enhancements are not precluded, if any.Note 3: The procedure ofLl / L2 based inter-cell mobility are applicable to the following scenarios:• Standalone, Carrier Aggregation (CA) and NR Carrier Aggregation (DC) case with serving cell change within one Cell Group (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 Frequency Range 1 (FR1) and FR2• Source and target cells may be synchronized or non-synchronized[3] 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”).[4] A basic principle with Ll / L2-triggered mobility 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 or one or more Information Elements (IEs) / fields / parameters such as CellGroupConfig. The UE performs measurements on these LTM candidate cells and transmits corresponding measurement reports to the network. The network then triggers the execution of a LTM cell switch procedure in the UE to one of these LTM candidate cells by transmitting lower layer signaling in a Medium Access Control (MAC) Control Element (CE), sometimes also referred to as a “LTM cell switch command”, to the UE, which then connects to the particular LTM candidate cell and switches to the LTM candidate cell configuration.[5] RAN2 has also agreed the following for LI / L2 -triggered mobility in Rel-18:- No security update support in Rel-18 with L1 / L2 based mobility.- RAN2 to confirm that the CellGroupConfig IE is (mandatory) needed within an LTM candidate cell configuration.The RadioBearerConfig IE can be optionally supported in an LTM candidate configurationThe MeasConfig IE can be optionally supported in an LTM candidate configuration.The OtherConfig IE is not required to be part of the LTM candidate cell configuration.The LTM candidate cell configuration should be designed as a To AddMod / ToRelease structure.The LTM candidate cell configuration Abstract Syntax Notation (ASN.1) structure comprises at least a CellGroupConfig IE and a configuration Identifier (ID).On Delta ConfigurationA UE stores the reference configuration as a separate configuration.The reference configuration is managed separately agree to use Model 1 : One RRCReconfiguration message for each candidate target configuration RRCReconfiguration to configure target candidate cells[6] Further, RAN3 has agreed for Ll / L2-triggered mobility in Rel-18:- For inter-DU case, the target NR base station (gNB) DU indicates the gNB-CU about the UE successful access to the target cell by Access Success message.Intra-CU User Plane (UP) case: CU will start data transmission after LTM cells switch signaling from DU including target cell ID.L3 Mobility in RRC CONNECTED in Long-Term Evolution (LTE) and NR[7] An RRC CONNECTED UE in LTE (also called “EUTRA”) can be configured by the network to perform measurements and, upon triggering measurement reports, the network may send a handover command to the UE (in LTE an RRConnectionReconfiguration with a field called mobilityControlInfo, and in NR, an RRCReconfiguration with a reconfigurationWithSync field).[8] These reconfigurations are prepared by the target cell upon a request from the source node (over an X2 interface in the case of EUTRA Evolved Packet Core (EPC), or an Xn interface in the case of EUTRA5G Core Network (5GC) or NR) and takes into account theexisting RRC configuration the UE has with the source cell (which are provided in the internode request). Among other parameters, the reconfiguration provided by the target cell contains all the information the UE needs to access the target cell, e.g., random access configuration, a new Cell Radio Network Temporary Identifier (C-RNTI) assigned by the target cell and security parameters enabling the UE to calculate new security keys associated to the target cell so the UE can send a handover complete message on Signaling Radio Bearer 1 (SRB1) (encrypted and integrity protected) based on new security keys upon accessing the target cell.[9] Figure 1 summarizes the signalling flow between a UE 102, source node 104 and target node 106 during a layer 3 handover procedure, as also described in 3 GPP Technical Specification (TS) 38.300 vl7.4.0.

[0010] As illustrated in Figure 1, the main steps during an inter-gNB handover procedure are as follows:Step 108: The source gNB 104 initiates handover and issues a HANDOVER REQUEST over the Xn interface.Step 110 and 112: The target gNB 106 performs admission control and provides the new RRC configuration as part of the HANDOVER REQUEST ACKNOWLEDGE.Step 114: The source gNB 104 provides the RRC configuration to the UE 102 by forwarding the RRCReconfiguration message received in the HANDOVER REQUEST ACKNOWLEDGE. The RRCReconfiguration message includes at least cell ID and all information required to access the target cell so that the UE 102 can access the target cell without reading system information. In some cases, the information required for contention-based and contention-free random access can be included in the RRCReconfiguration message. The access information to the target cell may include beam specific information, if any.Step 116 and 118: The UE 102 moves the RRC connection to the target gNB 106 and replies with the RRCReconfigurationComplete.SUMMARY

[0011] There currently exist certain challenge(s). As can be read in the above discussed 3GPP Rel-18 Work Item Description (WID) for Further NR Mobility Enhancements, it is limited to “Intra-DU case and intra-CU inter-DU case”, where DU and CU refers to the Distributed Unit and Central Unit in a distributed CU / DU RAN architecture. This means that in Rel-18, L1 / L2-triggered mobility is limited to intra-CU cases. Thus, for mobility between gNBs / CUs, LTM cannot be used.

[0012] A possible evolution of LTM is to extend it to cover also inter-CU / inter-gNB mobility. As part of such an evolution, one problem is to perform the configuration of inter-CU mobility, including adding, modifying, and releasing the LTM candidate cell configuration for inter-CU LTM candidate cells.

[0013] Figure 2 illustrates the signaling flow between a UE 202, a gNB-DU 204, and a gNB- CU 206, for the intra-CU inter-DU case, to be captured in 3GPP TS 38.401 vl8.1.0. The steps of Figure 2 are as follows.At step 208, user data is exchanged between the UE 202 and the gNB-DU 204, and between the gNB-DU 204 and the gNB-CU 206.At step 210, an L3 measurement control and reports procedure is performed between the UE 202, the gNB-DU 204, and the gNB-CU 206.At step 212, an LTM configuration decision is made at the gNB-CU 206.At step 214, the gNB-CU 206 transmits, to the gNB-DU 204, a UE CONTEXT MODIFICATION REQUEST message.At step 216, the gNB-DU 204 transmits, to the gNB-CU 206, a UE CONTEXT MODIFICATION RESPONSE message.At step 218, the gNB-CU 206 transmits, to the gNB-DU 204, a Downlink (DL) RRC MESSAGE TRANSFER message (including an RRCReconfiguration message).At step 220, the gNB-DU 204 transmits, to the UE 202, an RRCReconfiguration message. At step 222, the UE 202 transmits, to the gNB-DU 204, an RRCReconfigurationComplete message.At step 224, the gNB-DU 204 transmits, to the gNB-CU 206, an Uplink (UL) RRC MESSAGE TRANSFER message (including an RRCReconfigurationComplete message). At step 226, the UE 202 transmits, to the gNB-DU 204, a lower layer measurement report. At step 228, the gNB-DU 204 makes an inter-cell mobility execution decision.At step 230, the gNB-DU 204 transmits, to the UE 202, an LTM command.At step 232, the gNB-DU 204 transmits, to the gNB-CU 206, LTM signalling (including a Target Cell ID).At step 234, the gNB-DU 204 transmits, to the gNB-CU 206, a DL data delivery status.At step 236, the gNB-DU 204 detects the UE 202 access. The details of this step are for future study.- At step 238, the gNB-DU 204 transmits, to the gNB-CU 206, an ACCESS SUCCESS message (including a Target Cell ID).At step 240, the gNB-CU 206 transmits, to the gNB-DU 204, a UE CONTEXT MODIFICATION REQUEST message (including prepared cells to be released).At step 242, the gNB-DU 204 transmits, to the gNB-CU 206, a UE CONTEXT MODIFICATION RESPONSE message.At step 244, user data is exchanged between the UE 202 and the gNB-DU 204, and between the gNB-DU 204 and gNB-CU 206.

[0014] One challenge when extending LTM to include also the inter-CU use case is the control of whether a security key change is needed or not for each LTM cell switch. If the LTM candidate cell is controlled by a different CU than the current serving cell, a security key change is needed at LTM cell switch. If the LTM candidate cell is controlled by the same CU as the serving cell, a security key change is not needed. In case the UE is configured with several LTM candidate cells, controlled by different CUs, it may not be possible to determine whether a security key is needed or not at the time of LTM candidate cell configuration. The UE may trigger subsequent LTM cell switches within the set of configured LTM candidate cells, and thus the need for security key change will depend on from which LTM candidate cell to which LTM candidate cell the UE is moving.

[0015] Figure 3 illustrates an example of distributed CU / DU RAN architecture with two CUs, CUI 302 and CU2 304, each controlling a DU, DU1 306 and DU2 308, where DU1 306 controls cells X and A and DU2 308 controls cells B and C. It is assumed that the UE has cell X as a serving cell and receives LTM candidate cell configurations for cells A, B and C. Since cell A is connected to the same CU as cell X, security key change is not needed for that LTM candidate configuration, but for cells B and C, which are connected to another CU, the security key change is needed. It is assumed that an LTM cell switch is executed to cell B. The LTM candidate cell configuration for cell B indicates to the UE to change the security key, which is correct since the CU was changed from CUI 302 to CU2 304. However, consider now that a second LTM cell switch is executed to cell C. The LTM candidate cell configuration for cell C also indicates to the UE to change the security key, since coming from cell X a security key change would have been needed. However, the UE is now moving from cell B to cell C, which does not require a security key change since they are controlled by the same CU2 304, so the key change is in this case unnecessary. A worse situation occurs if a subsequent LTM cell switch is now triggered from cell C to cell A. The LTM candidate cell configuration for cell Aindicates that no security key change is needed, since coming from cell X to cell A, a security key change is not needed. However, the UE is now moving from cell C to cell A, which does require a security key change since they are controlled by different CUs. Not executing the security key change in this case would compromise security as the same security key may not be used by two network nodes. A challenge is that the need for security key change during LTM will depend on whether the source and target cells during LTM execution are operated by the same or different CUs. Since this situation will change as the UE executes subsequent LTM cell changes, it would require the network to provide updated LTM candidate cell configurations to the UE each time the UE changes the CU. This would cause additional signalling, especially in ping-pong LTM cell switch situations between different CUs.

[0016] Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. In order to address the above challenges, the disclosure presents methods for a User Equipment (UE) to execute inter-CU LTM configuration, comprising receiving, from a first network node, a reconfiguration message including at least one inter-CU LTM candidate cell configuration.

[0017] In a first aspect of the disclosure, there is provided a method performed by a user equipment. The method comprises receiving, from a network node, a configuration for use in connecting to and / or communicating with a candidate cell following a lower-layer cell mobility procedure. The configuration comprises information that enables the user equipment to refresh one or more security keys for use in connecting to and / or communicating with the candidate cell.

[0018] In a second aspect of the disclosure, there is provided a method performed by a network node. The method comprises transmitting, to a user equipment, a configuration for use in connecting to and / or communicating with a candidate cell following a lower-layer cell mobility procedure. The configuration comprises information that enables the user equipment to refresh one or more security keys for use in connecting to and / or communicating with the candidate cell.

[0019] In a third aspect of the disclosure, there is provided a method performed by a second network node. The method comprises receiving, from a first network node, a request message comprising a request for the second network node to transmit a configuration for use by a user equipment in connecting to and / or communicating with a candidate cell served by the second network node following the lower-layer cell mobility procedure.

[0020] In a fourth aspect of the disclosure, there is provided a user equipment. The user equipment comprises processing circuitry configured to cause the user equipment to perform the method of any embodiment of the first aspect.

[0021] In a fifth aspect of the disclosure, there is provided a network node. The network node comprises processing circuitry configured to cause the network node to perform the method of any embodiment of the second aspect.

[0022] In a sixth aspect of the disclosure, there is provided a second network node. The second network node comprises processing circuitry configured to cause the second network node to perform the method of any embodiment of the third aspect.

[0023] In some methods, the at least one inter-CU LTM candidate cell configuration includes information to perform security key refresh, (such as a RRC IE MasterKeyUpdate or a RRC IE RadioBearerConfig that includes SecurityConfig with Security AlgorithmConfig).

[0024] In some methods, the UE receives, from the network, with the inter-CU LTM candidate cell configuration, the security information enabling the UE to perform security key refresh (e.g., configuration of ciphering and integrity protection algorithm(s)); and, at least partially derives one or more security keys before the UE receives the LTM cell switch command indicating the inter-CU LTM candidate cell configuration.

[0025] In some methods, the at least one inter-CU LTM candidate cell configuration uses delta configuration on top of a reference configuration.

[0026] The disclosure also presents methods for a first network node, such as a first gNB or a first CU, to perform inter-CU LTM configuration for a UE, comprising, transmitting, to the UE, a reconfiguration message including an inter-CU LTM candidate cell configuration.

[0027] In some methods, the first network node transmits, to a second network node, a request message to perform configuration of an inter-CU LTM candidate cell. In some methods, the first network node receives, from a second network node, a response message including at least one inter-CU LTM candidate cell configuration.

[0028] The disclosure also presents methods for a second network node, such as a second gNB or a second CU, to perform inter-CU LTM configuration for a UE, comprising, receiving, from a first network node, a request message to perform configuration of an inter-CU LTM candidate cell.

[0029] In some methods, the second network node transmits, to the first network node, a response message including at least one inter-CU LTM candidate cell configuration.

[0030] Certain embodiments may provide one or more of the following technical advantage(s). The proposed solution enables the UE to receive from the first network node (such as a source gNB or a source CU) a measurement configuration for inter-CU LTM candidate cell(s) and at least one inter-CU LTM candidate cell configuration, which can be used to for inter-CU LTM configuration and therefore enables LI measurements on inter-CU LTM candidate cell(s) execution of an inter-CU LTM cell switch procedure.BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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:

[0032] Fig. 1 shows an L3 handover procedure;

[0033] Fig. 2 shows a signaling flow for LTM in intra-CU / inter-DU;

[0034] Fig. 3 shows an example distributed CU / DU RAN architecture;

[0035] Fig. 4 shows a system according to embodiments of the disclosure;

[0036] Fig. 5 is a flow chart illustrating a method in accordance with some embodiments;

[0037] Fig. 6 is a flow chart illustrating a method in accordance with some embodiments;

[0038] Fig. 7 is a flow chart illustrating a method in accordance with some embodiments;

[0039] Figs. 8 and 9 are signalling diagrams according to embodiments of the disclosure;

[0040] Fig. 10 is a flow chart illustrating a method according to an embodiment of the disclosure;

[0041] Fig. 11 is a signaling diagram illustrating a handover preparation procedure;

[0042] Fig. 12 is a signaling diagram illustrating an unsuccessful operation in a handover preparation procedure;

[0043] Fig. 13 shows an example of a communication system in accordance with some embodiments;

[0044] Fig. 14 shows a UE in accordance with some embodiments;

[0045] Fig. 15 shows a network node in accordance with some embodiments;

[0046] Fig. 16 is a block diagram of a host;

[0047] Fig. 17 is a block diagram illustrating a virtualization environment in which functions implemented by some embodiments may be virtualized; and

[0048] Fig. 18 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.DETAILED DESCRIPTION

[0049] 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.

[0050] The text 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”, “Ll- mobility”, “LI based mobility”, “Ll / L2-centric inter-cell mobility”, “L1 / L2 inter-cell mobility”, “Ll / L2-Triggered Mobility”, “Lower-layer triggered Mobility” or “LTM”. The basic principle is that the UE normally 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 sometimes 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 Master Cell Group (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.

[0051] 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 the 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.

[0052] 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).

[0053] An LTM cell switch procedure may be triggered in the UE by reception of a LTM cell switch command, or alternatively, triggered by some other event, such as a condition, e,g, a triggering condition used for conditional configuration, such as conditional handover, being fulfilled, as a result of recovery from radio link failure or handover failure.

[0054] The text refers to an inter-CU LTM cell switch procedure, which is an LTM cell switch procedure resulting in a change of serving cell, e.g. change of SpCell, PCell, PSCell, to an LTM candidate cell controlled by a different gNB than the source gNB or serving gNB of the UE upon reception of the LTM cell switch command. From UE point of view, the actions performed during an inter-CU LTM cell switch procedure may be the same type of actions of an LTM cell switch procedure, but may also include additional actions, such as change of security key.

[0055] The text 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 an LTM cell switch procedure. 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. Channel State Information (CSI) measurements) so that the UE reports these measurements and network may take educated decision on which beam (e.g. Transmission Configuration Indication (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).

[0056] The text 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 Ll / 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 indicating the UE to perform a LTM cell switch procedure to that LTM candidate cell, which becomes the target cell and the current (new) SpCell, or an SCell in a servingfrequency. 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. An LTM candidate cell configuration is associated with an identifier which is used in the signaling when referring to a certain LTM candidate cell configuration, such as when the UE receives the LTM candidate cell configuration and when the UE receives an LTM cell switch command indicating the UE to perform a LTM cell switch procedure to that LTM candidate cell. This identifier is sometimes known as the LTM candidate cell configuration identity or LTM candidate configuration index (or similar).

[0057] 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 an LTM candidate cell configuration indicated with a candidate configuration index (sometimes also denoted candidate configuration ID). The UE may be configured with multiple LTM candidate cell configurations, so a Candidate 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 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).

[0058] The text refers to an inter-CU LTM candidate cell configuration. An inter-CU LTM candidate cell configuration is a LTM candidate cell configuration which contains theconfiguration which the UE needs to start to operate accordingly when it performs an LTM cell switch procedure to an LTM candidate cell which is controlled by a different base station, e.g. gNB, from the current source base station e.g. serving gNB of the UE. An inter-CU LTM candidate cell configuration may be the same as an LTM candidate cell configuration but it may also include additional information than what is included in the LTM candidate cell configuration used for inter-CU cell switch. This additional information may be, for example:• Information to perform security key refresh, e.g. the RRC IE MasterKeyUpdate or a RRCIE RadioBearerConfig that includes SecurityConfig with Security AlgorithmConfig• Indication to perform a full configuration, e.g. the RRC field fullConfig

[0059] The term security key refresh refers to that the UE changes its security key, e.g. during a mobility procedure such as an inter-CU LTM cell switch procedure. A security key refresh may comprise at least one of• The UE receives a Master Key Update parameter / IE (e.g. masterKeyUpdate) included in the inter-CU LTM candidate cell configuration (e.g. set by the Target CU).• When a Non-Access Stratum (NAS) indication (e.g. nas-Container) is received (e.g. within the Master Key Update parameter / IE) the UE forwards the NAS indication to the upper layer (e.g. UE NAS layer);• When a key set change indication (e.g. keySetChangelndicator) is received and / or is set to ‘true’ (e.g. within the Master Key Update parameter / IE) the UE derives or updates the KSNB key based on the KAMF key, as specified in TS 33.501 vl8.1.0;• The UE derives or updates the KSNB key (for the inter-CU LTM candidate cell configuration indicated in the LTM cell switch command) based on the current KSNB key or the Next Hop (NH), using the Next Hop Chaining Count (e.g. nextHopChainingCounf) value indicated in the received Master Key Update parameter / IE (e.g. MasterKeyUpdate), as specified in TS 33.501;• The UE derives the KRRCenc and Kupenc keys associated with a ciphering algorithm (e.g. cipheringAlgorithm indicated in the securityAlgorithmConfig), as specified in TS 33.501;• The UE derives the KRRCint and Kupint keys associated with an integrity protection algorithm (e.g. integrityProtAlgorithm indicated in the securityAlgorithmConfig), as specified in TS 33.501;• The UE receives a security algorithm configuration included in the inter-CU LTM candidate cell configuration, based on which the UE derives User plane keys and / or controlplane keys (e.g. for encryption and / or integrity protection) e.g. the KRRCenc and KuPenc keys, the KRRCint and Kupint keys.• The UE uses its current security algorithm configuration, based on which the UE derives User plane keys and / or control plane keys (e.g. for encryption and / or integrity protection) e.g. the KRRCenc and KuPenc keys, the KRRCint and Kupint keys.• The UE applies the provided ciphering algorithm and key during a Packet Data Convergence Protocol (PDCP) entity re-establishment procedure;• The UE applies the provided integrity protection algorithm and key during an PDCP entity re-establishment procedure.

[0060] Certain methods described herein comprise the UE deriving the security key(s) when LTM is configured, which are only used when the UE performs the LTM cell switch. In these cases, when the UE is configured with an LTM candidate cell (e.g. a candidate to be a PCell) the UE derives one or more security key(s) associated to that LTM candidate cell (e.g. UP integrity protection key, Control Plane (CP) integrity protection key, UP encryption / ciphering key, CP encryption / ciphering key), but only starts to use one of the derived security key(s) when it performs the inter-CU LTM cell switch procedure.

[0061] Figure 4 illustrates a system structure including the entities involved in embodiments of the disclosure. The User Equipment (UE) 402 is a wireless terminal, such as a cellular smartphone, sometimes connected to the first network node 404 over a wireless interface 408 and sometimes connected to a second serving network node 406, to which the UE 402 is connected over a wireless interface 410. Further detail regarding a UE and a network node according to embodiments of the disclosure is set out with respect to Figures 14 and 15 respectively.

[0062] The first network node 404 controls a first cell 414 (sometimes called cell or SpCell). The second network node 406 controls a second cell 416, which sometimes, e.g. in the context of mobility, is referred to as target cell, neighbour cell, candidate cell, LTM candidate cell or inter-CU LTM candidate cell.

[0063] Each of the first network node 404 and the second network node 406 may be a base station such as, when they e.g. are part of NG-RAN, e.g. a gNB. The first network node and the second network node are connected over an interface 412, which may be an Xn or Xn-C type of interface, for example when the first network node and second network node are of type gNB and part of an NG-RAN.

[0064] In the case of a distributed CU / DU RAN architecture, each of the first network node 404 and / or the second network node 406 may be divided into a distributed unit, sometimes known as gNB-DU or DU, and a central unit, CU, sometimes referred to as gNB-CU, CU, gNB-CU- CP or gNB-CU-UP. Thus, in such a case the first network node 404 may be divided into a first central unit, CU 418 and a first distributed unit, DU, 420, and second network node 406 may be divided into a second central unit, CU 424 and a second distributed unit, DU, 426. The first CU 418 and the first DU 420 are connected over an interface 422, which may be an Fl type of interface in case of NG-RAN. Correspondingly, the second CU 424 and the second DU 426 are connected over an interface 428, which may be an Fl type of interface in case of NG-RAN.

[0065] The first network node 404 and the second network node 406 are connected to a third network node 430 over interfaces 432 and 434, respectively. The third network node 430 may be a core network node such as, in case of 5GC, a User Plane Function (UPF) or an Access and Mobility management Function (AMF). In such a case the interfaces 432 and 434 may be an NG type of interface.

[0066] Figure 5 depicts a method in accordance with particular embodiments. The method of Figure 5 may be performed by a UE or wireless device (e.g. the UE 1312 or UE 1400 as described later with reference to Figures 13 and 14 respectively). The steps provide a method by which a user equipment or wireless device can execute inter-CU LTM configuration and an inter-CU LTM cell switch procedure.

[0067] In some respects, the method of Figure 5 corresponds to the set of embodiments numbered Al to A10 that follow the description of Figure 5, the group A embodiments, the signalling of the UE in any of Figures 8 to 9, and / or the method described below with respect to Figure 10. The description of method of Figure 5 should also be read in conjunction with the methods of Figures 6 and 7, which set out complementary steps performed by the first network node and the second network node respectively.

[0068] The method begins at step 502 with receiving a configuration from a network node.

[0069] In some examples, the configuration may be for use in connecting to and / or communicating with a candidate cell following a lower-layer cell mobility procedure. In some examples, the lower-layer cell mobility procedure comprises an L1 / L2 triggered mobility, LTM, procedure. In some examples, the network node comprises a first centralized unit, CU, or a first base station. In some examples, the candidate cell is served by a second CU or a second base station. In some examples, the configuration comprises information that enables the user equipment to refresh one or more security keys for use in connecting to and / orcommunicating with the candidate cell. It will be appreciated this information enables the UE to change its security key during a mobility procedure such as an inter-CU LTM cell switch procedure.

[0070] For example, the information that enables the user equipment to refresh one or more security keys may comprise one or more of: an indication of a master key update parameter; an indication of one or more security algorithms to be used by the user equipment to derive one or more user plane keys and / or one or more control plane keys. For example, the one or more security keys may comprise a master key for a network node serving the candidate cell.

[0071] In some examples, the configuration further comprises a measurement configuration comprising an instruction for the user equipment to perform measurements on transmissions by the candidate cell. Additionally or alternatively, the configuration may comprise one of: a full configuration; and a delta configuration defining one or more differences relative to a reference configuration. Additionally or alternatively, the configuration may comprise an indication of one or more source cells. For example, the indication of one or more source cells may comprise one or more of: one or more cell IDs; one or more physical cell identifiers; one or more source cell configuration identifiers; and an identifier of a group of one or more cells.

[0072] In these examples, the user equipment may determine whether to refresh the one or more security keys based on whether or not the lower-layer mobility procedure was from one of the one or more source cells. That is, the indication of one or more source cells may indicate to the UE whether or not to perform the security key change when executing an LTM cell switch.

[0073] In step 504, the UE transmits a report message to the network node. For example, the report message may comprise an indication of values derived from the measurements on transmissions by the candidate cell.

[0074] In step 506, the UE receives a command to execute a lower-layer cell mobility procedure to a candidate cell. In some examples, the UE receives, via lower-layer signalling from a source network node, a command to switch to the candidate cell. In some examples, the command comprises an indication that the candidate cell is served by a different CU or a different base station than the source network node.

[0075] The lower-layer signalling may comprise one or more of: LI and L2 signalling. Additionally or alternatively, the lower-layer signalling may comprise one or more of: Medium Access Control, MAC, signalling and Physical, PHY, layer signalling.

[0076] In step 508, the UE derives one or more security keys for use in communicating with the candidate cell. For example, the UE may, upon executing a lower-layer cell mobility procedureto the candidate cell, use the information to determine one or more security keys. In another example, the UE may, prior to executing the lower-layer cell mobility procedure to the candidate cell, use the information to determine one or more security keys. For example, the UE may use the information to determine the one or more security keys upon reception of the configuration. That is, the step 508 may be performed in advance of an execution of a lower- layer cell mobility procedure to a candidate cell. This may reduce latency upon execution of the lower-layer cell mobility procedure to a candidate cell.

[0077] In step 510, the UE uses the security key(s) to connect to and / or communicate with the candidate cell.

[0078] The following numbered statements set out further detail of methods performed by a UE according to embodiments of the disclosure, which should be read in conjunction with the flowchart shown in Figure 5.

[0079] Al. Methods for a User Equipment, UE, to execute inter-CU LTM configuration and an inter-CU LTM cell switch procedure, comprising receiving, from a first network node, a reconfiguration message including an LTM configuration including at least one inter-CU LTM candidate cell configuration and a measurement configuration, and performing measurements on the inter-CU LTM candidate cell(s).

[0080] Ala. The method in Al wherein the UE transmits, to the first network node, a response message to confirm it has received and stored the inter-CU LTM candidate cell configuration. In one example the response message can be RRCReconfigurationComplete

[0081] Alb. The method in Al wherein the UE transmits, to the first network node, lower-layer measurement reports for inter-CU LTM candidate cell(s).

[0082] Ale. The method in Al wherein the UE executes an inter-CU LTM cell switch procedure and applies an inter-CU LTM candidate cell configuration.

[0083] Aid. The method in Ale wherein the UE receives an LTM cell switch command.

[0084] Ale. The method in Ale wherein the measurement configuration includes one or more of:• an indication to perform measurements on the received inter-CU LTM candidate cell(s).• RS configuration per inter-CU LTM candidate cell• CSI resource configuration per inter-CU LTM candidate cell

[0085] A2. The method in Al wherein the at least one inter-CU LTM candidate cell configuration includes information to perform security key refresh (for example, a Master KeyUpdate parameter (e.g. the RRC IE MasterKeyUpdate), or an RRC IE RadioBearerConfig that includes a security algorithm configuration (e.g. SecurityConfig with Security AlgorithmConfig) which the UE uses to derive the user plane keys and / or control plane keys (e.g. for encryption and / or integrity protect! on)). In some embodiments, the information to perform security key refresh may comprise an indication whether or not to perform the security key change.

[0086] In one embodiment, the indication is a list of cell IDs or Physical Cell Identities (PCIs). In this embodiment, a UE executing LTM cell switch from a cell included in the list shall perform security key change.

[0087] In another embodiment, the indication is a list of LTM candidate cell configuration IDs. In this embodiment, a UE executing LTM cell switch from a LTM candidate cell configuration ID included in the list shall perform security key change.

[0088] In another embodiment, the indication is a list of cell IDs or PCIs. In this embodiment, for LTM cell switch among the listed cell IDs or PCIs, security key change is not performed. Only for a LTM cell switch from a cell ID or PCI not included in the list, a security key change is performed.

[0089] In another embodiment, the indication is a list of LTM candidate cell configuration IDs. In this embodiment, for LTM cell switch among the listed LTM candidate cell configuration IDs, security key change is not performed. Only for a LTM cell switch from a LTM candidate cell configuration ID not included in the list, a security key change is performed.

[0090] In another embodiment, the indication is a group indicator. The group indicator contains a group identifier. It can be a number 1,2,3... or a character A, B, C... or similar. In this embodiment, as long as the UE moves between LTM candidate configurations including the same group indicator, security key refresh / exchange is not performed. Only when the UE moves between a LTM candidate configurations including different group indicator, is a security key change performed.

[0091] A3. The method in Al wherein the at least one inter-CU LTM candidate cell configuration uses delta configuration on top of a reference configuration. The delta configuration indicates the differences between the reference configuration and the configuration which is intended for use. The configuration for use by the UE is then generated by the UE by applying the delta configuration to the reference configuration. In this way, the delta configuration which is signalled to the UE may be smaller in size than the full configuration.

[0092] A3a. The method in Al wherein the at least one inter-CU LTM candidate cell configuration uses complete configuration or full configuration.

[0093] The method according to A3 a, where the inter-CU LTM candidate cell configuration includes an indication that it uses complete configuration.

[0094] The method according to A3 a, where the inter-CU LTM candidate cell configuration includes an indication that it uses full configuration, such as the RRC field fullConfig.

[0095] A3b. The method in Al wherein the UE receives a reference configuration to be applied with the received inter-CU LTM candidate cell configuration.

[0096] The method according to A3b, where the reference configuration for the inter-CU LTM candidate configuration is different from the reference configuration that the UE may receive for intra-CU LTM candidate cell configuration(s). In such a case the UE stores both reference configurations and uses one or the other based on if the LTM cell switch command indicates an inter-CU LTM candidate cell configuration or an intra-CU LTM candidate cell configuration.

[0097] The method according to A3b, where the reference configuration for the inter-CU LTM candidate configuration is the same as the reference configuration that the UE may receive for intra-CU LTM candidate configuration(s). In such a case the UE stores only one reference configuration and use it regardless of if the LTM cell switch command indicates an inter-CU LTM candidate cell configuration or an intra-CU LTM candidate cell configuration. In one option of this method, the network may send a reference configuration for an inter-CU LTM candidate cell configuration and another reference configuration for an intra-CU LTM candidate cell configuration and the UE comparing them may understand that there are the same. In another option of this method, the network may explicitly indicate whether the reference configuration for an inter-CU LTM candidate cell configuration and a reference configuration for an intra-CU LTM candidate cell configuration are the same.

[0098] A4. The method in Al wherein the UE receives, from a network node, an LTM cell switch command indicating an inter-CU LTM candidate cell configuration.

[0099] A5. The method in Al wherein the UE transmits, to the first network node, a measurement report of an inter-CU LTM candidate cell.

[0100] The method according to A5, wherein the measurement report is an L3 measurement report, such as an RRC measurement report.

[0101] The method according to A5, wherein the measurement report is a lower-layer measurement report, such as LI or MAC measurement report.

[0102] A6. The method in Al wherein the UE keeps an inter-CU LTM candidate cell configuration after executing the inter-CU LTM cell switch procedure.

[0103] A7. The method in Al wherein the UE releases an inter-CU LTM candidate cell configuration after executing the inter-CU LTM cell switch procedure.

[0104] A8. The method in Al wherein the UE keeps an inter-CU LTM candidate cell configuration but considers the candidate cell as deactivated, after executing the inter-CU LTM cell switch procedure (for example, the UE does not perform LI measurement reporting and TA management towards a deactivated candidate cell).

[0105] A9. The method in Al wherein the UE transmits to the second network node an uplink signalling to indicate that the inter-CU LTM candidate cell configuration has been correctly applied and that the LTM cell switch procedure has been completed.

[0106] A10. The method in Al wherein the UE performs security key refresh.

[0107] The method according to A10, wherein the security key refresh comprises one or more of• The UE receives a Master Key Update parameter / IE (e.g. masterKeyUpdate) included in the inter-CU LTM candidate cell configuration (e.g. set by the Target network node 406 or by the Target CU 428).• When a Non-Access Stratum (NAS) indication (e.g. nas-Container) is received (e.g. within the Master Key Update parameter / IE) the UE forwards the NAS indication to the upper layer (e.g. UE NAS layer);• When a key set change indication (e.g. keySetChangelndicator) is received and / or is set to ‘true’ (e.g. within the Master Key Update parameter / IE) the UE derives or updates the KgNB key based on the KAMF key, as specified in TS 33.501 vl8.1.0;• The UE derives or updates the KgNB key (for the inter-CU LTM candidate cell configuration indicated in the LTM cell switch command) based on the current KgNB key or the NH, using the Next Hop Chaining Count (e.g. nextHopChainingCount) value indicated in the received Master Key Update parameter / IE (e.g. MasterKeyUpdate), as specified in TS 33.501 vl8.1.0;• The UE derives the KRRCenc and KUPenc keys associated with a ciphering algorithm (e.g. cipheringAlgorithm indicated in the security AlgorithmConfig), as specified in TS 33.501 vl8.1.0;• The UE derives the KRRCint and KUPint keys associated with an integrity protection algorithm (e.g. integrityProtAlgorithm indicated in the security AlgorithmConfig), as specified in TS 33.501 vl8.1.0;• The UE receives a security algorithm configuration included in the inter-CU LTM candidate cell configuration, based on which the UE derives User plane keys and / or control plane keys (e.g. for encryption and / or integrity protection) e.g. the KRRCenc and KUPenc keys, the KRRCint and KUPint keys.• The UE uses its current security algorithm configuration, based on which the UE derives User plane keys and / or control plane keys (e.g. for encryption and / or integrity protection) e.g. the KRRCenc and KUPenc keys, the KRRCint and KUPint keys;• The UE applies the provided ciphering algorithm and key during an PDCP entity re-establishment procedure;• The UE applies the provided integrity protection algorithm and key during a PDCP entity re-establishment procedure.

[0108] Figure 6 depicts a method in accordance with particular embodiments. The method of Figure 6 may be performed by a first network node (e.g. the network node 1310 or network node 1500 as described later with reference to Figures 13 and 15 respectively). The steps provide a method by which a first network node performs inter-CU LTM configuration for a UE.

[0109] In some respects, the method of Figure 6 corresponds to the set of embodiments numbered Bl to B8 that follow the description of method of Figure 6, the group B embodiments, and / or the signalling of the source gNB and / or source DU and / or source CU in any of Figures 8 to 9. The description of method of Figure 6 should also be read in conjunction with the methods of Figure 5 and 7, which set out complementary steps performed by the UE, and the second network node respectively.[HO] In some examples, the first network node comprises a first centralized unit, CU, or a first base station. In these examples, the candidate cell is served by a second CU or a second base station.[Hl] The method begins at step 602 with transmitting a request message to a second network node. In some examples, the request message comprises a request for the second network node to transmit a configuration for use in connecting to and / or communicating with the candidate cell following the lower-layer cell mobility procedure. The lower-layer cell mobility proceduremay comprise an L1 / L2 triggered mobility, LTM, procedure. In some examples, the request message may comprise a handover request message. Additionally or alternatively, the request message may comprise a request for the second network node to transmit a plurality of configurations for a plurality of candidate cells served by the second network node.

[0112] In step 604, the first network node receives the configuration from the second network node. In some examples, the configuration is for use in connecting to and / or communicating with the candidate cell following the lower-layer cell mobility procedure.

[0113] In step 606, the first network node transmits the configuration to a UE.

[0114] In some examples, the configuration is for use in connecting to and / or communicating with a candidate cell following a lower-layer cell mobility procedure, and the configuration comprises information that enables the user equipment to refresh one or more security keys for use in connecting to and / or communicating with the candidate cell. In some examples, the information that enables the user equipment to refresh one or more security keys comprises one or more of: an indication of a master key update parameter; an indication of one or more security algorithms to be used by the user equipment to derive one or more user plane keys and / or one or more control plane keys. For example, the one or more security keys may comprise a master key for a network node serving the candidate cell.

[0115] In some examples, the configuration comprises an indication of one or more source cells, for use by the user equipment in determining whether to refresh the one or more security keys based on whether or not the lower-layer mobility procedure was from one of the one or more source cells. In some examples, the indication of one or more source cells comprises one or more of: one or more cell IDs; one or more physical cell identifiers; one or more source cell configuration identifiers; and an identifier of a group of one or more cells.

[0116] In some examples, the configuration further comprises a measurement configuration comprising an instruction for the user equipment to perform measurements on transmissions by the candidate cell. Additionally or alternatively, the configuration may comprise one of: a full configuration; and a delta configuration defining one or more differences relative to a reference configuration.

[0117] In step 608, the first network node receives a report message from the UE. In some examples, the report comprises an indication of values derived from the measurements on transmissions by the candidate cell.

[0118] In step 610, the first network node transmits a lower-layer mobility command to the UE. In some examples, the command is a command to switch to the candidate cell. In someexamples, the command comprises an indication that the candidate cell is served by a different CU or a different base station than the source network node (e.g., and / or that security key refresh is required as part of the lower-layer cell mobility procedure). The lower-layer signalling may comprise one or more of: LI and L2 signalling. Additionally or alternatively, the lower-layer signalling comprises one or more of: Medium Access Control (MAC) signalling and Physical (PHY) layer signalling.

[0119] The following numbered statements set out further detail of methods performed by the first network node according to embodiments of the disclosure.

[0120] B 1. Methods for a first network node, such as a first gNB or a first CU, to perform inter- CU LTM configuration for a UE, comprising, transmitting, to the UE, a reconfiguration message including at least one inter-CU LTM candidate cell configuration.

[0121] Bia. The method in Bl wherein the first network node receives, from the UE, a response message confirming the UE has received and stored the inter-CU LTM candidate cell configuration.

[0122] B2. The method in Bl wherein the first network node receives, from the UE, a measurement report of an inter-CU LTM candidate cell.

[0123] The method according to B2, wherein the measurement report is an L3 measurement report.

[0124] The method according to B2, wherein the measurement report is an LI or MAC measurement report.

[0125] B3. The method in Bl wherein the first network node transmits, to a second network node, a request message over Xn to generate at least one configuration of an inter-CU LTM candidate cell. The request message may be a Handover Request.

[0126] In one alternative of the method of B3, the request message includes a list of one or more inter-CU LTM candidate cells.

[0127] In another alternative of the method of B3, the request message includes only one inter- CU LTM candidate cell, and one or more messages are sent per cell basis.

[0128] B3a. The method in B 1 wherein the first network node transmits in the request to generate an inter-CU LTM candidate cell configuration also the current reference configuration for intra-CU LTM candidate configuration that is used by the UE.

[0129] B4. The method in B3 wherein the first network node receives, from a second network node, a response message including at least one inter-CU LTM candidate cell configuration. The response message may be a Handover Request Acknowledge.

[0130] In one alternative of the method of B4, the response message includes one or more inter- CU LTM candidate cell configurations.

[0131] In another alternative of the method of B4, one or more response message are received, each one including only one inter-CU LTM candidate cell configuration.

[0132] B5. The method in B3 wherein the at least one inter-CU LTM candidate cell configuration uses delta configuration on top of a reference configuration.

[0133] B5a. The method in B3 wherein the at least one inter-CU LTM candidate cell configuration uses complete configuration or full configuration.

[0134] The method according to B5, where the inter-CU LTM candidate cell configuration includes an indication that it uses complete configuration.

[0135] The method according to B5, where the inter-CU LTM candidate cell configuration includes an indication that it uses full configuration, such as the RRC field fullConfig.

[0136] B6. The method wherein the first network node transmits, to a second network node, a request to activate or deactivate LTM configuration of at least one inter-CU LTM candidate cell.

[0137] B7. The method in B6 wherein the first network node receives, from a second network node, a response message including the result of activation or deactivation of at least one inter- CU LTM candidate cell configuration.

[0138] B8. The method in B4 wherein the first network node receives, from a second network node, at least one inter-CU LTM candidate cell configuration including the security key parameters update and an indication whether or not to perform the security key change.

[0139] Figure 7 depicts a method in accordance with particular embodiments. The method of Figure 7 may be performed by a second network node (e.g. the network node 1310 or network node 1500 as described later with reference to Figures 13 and 15 respectively). The steps provide a method by which a second network node performs inter-CU LTM configuration for a UE.

[0140] In some respects, the method of Figure 7 corresponds to the set of embodiments numbered Cl to C6 that follow the description of method of Figure 7, the group B embodiments, and / or the signalling of the target gNB and / or target DU and / or target CU in any of Figures 6 to 9. The description of method of Figure 7 should also be read in conjunction with the methods of Figure 5 and 6, which set out complementary steps performed by the UE, and the first network node respectively.

[0141] The method begins at step 702 with receiving a request message from a first network node. For example, the request message may comprise a request for the second network node to transmit a configuration for use by a user equipment in connecting to and / or communicating with a candidate cell served by the second network node following the lower-layer cell mobility procedure. In some examples, the request message may comprise a handover request message. In some examples, the request message may comprise a request for the second network node to transmit a plurality of configurations for a plurality of candidate cells served by the second network node.

[0142] In step 704, the second network node transmits a configuration to the first network node. For example, the configuration may be for use in connecting to and / or communicating with the candidate cell following the lower-layer cell mobility procedure.

[0143] The following numbered statements set out further detail of methods performed by the second network node according to embodiments of the disclosure.

[0144] Cl. Methods for a second network node, such as a second gNB or a second CU, to perform inter-CU LTM configuration for a UE, comprising, receiving, from a first network node over Xn, a request message to generate the configuration of at least one inter-CU LTM candidate cell. The request message may be a Handover Request.

[0145] In one alternative of the method of Cl, the request message includes a list of one or more inter-CU LTM candidate cell.

[0146] In another alternative of the method of Cl the request message includes only one inter- CU LTM candidate cell, and one or more messages are received.

[0147] C2. The method in Cl wherein the second network node transmits, to the first network node, a response message including at least one inter-CU LTM candidate cell configuration. The response message may be a Handover Request Acknowledge.

[0148] In one alternative of the method of C2, the response message includes one or more inter- CU LTM candidate cell configuration.

[0149] In another alternative of the method of C2, one or more response message are sent, each one including only one inter-CU LTM candidate cell configuration.

[0150] C2a. The method in C 1 wherein the second network node transmits to the first network node, a reference configuration that has to be applied together with the generated inter-CU LTM candidate cell configuration.

[0151] In one alternative of the method C2a, the second network node transmits to the first network node a reference configuration, and this reference configuration may be different froma reference configuration that the UE needs to apply for intra-CU LTM candidate cell configuration(s).

[0152] In one alternative of the method C2a, the second network node transmits to the first network node an indication that the reference configuration to be applied for the inter-CU LTM candidate cell configuration is the same as that one that the UE applies for the intra-CU LTM candidate cell configurations.

[0153] C3. The method in C2 wherein the at least one inter-CU LTM candidate cell configuration uses delta configuration on top of a reference configuration.

[0154] C3a. The method in C2 wherein the at least one inter-CU LTM candidate cell configuration uses complete configuration or full configuration.

[0155] The method according to C3a where the inter-CU LTM candidate cell configuration includes an indication that it uses complete configuration.

[0156] The method according to C3a where the inter-CU LTM candidate cell configuration includes an indication that it uses full configuration, such as the RRC field fullConfig.

[0157] C4. The method where a second network node, to perform activation or deactivation of LTM configuration for a UE, comprises, receiving, from a first network node, a request message to deactivate configuration of at least one inter-CU LTM candidate cell.

[0158] C5. The method in C4 wherein the second network node transmits, to the first network node, a response message including at least activation or deactivation of one inter-CU LTM candidate cell configuration.

[0159] C6. The method in C2 wherein the second network node transmits, to the first network node, at least one inter-CU LTM candidate cell configuration including the security key parameters update and an indication whether or not to perform the security key change.Early key refresh

[0160] In certain embodiments of the disclosure, the UE receives information to perform security key refresh (e.g. the RRC IE MasterKeyUpdate or a RRC IE RadioBearerConfig that includes SecurityConfig with Security AlgorithmConfig) when the UE is configured with an LTM candidate cell, i.e., upon reception of a reconfiguration message (e.g. RRC Reconfiguration) configuring the LTM candidate cell, wherein the information may be associated to the LTM candidate cell being configured. In response to the reception of that information the UE performs one or more actions related to key refresh: for example, the UE derives one or more security key(s) associated to that LTM candidate cell (e.g. KgNB, UPintegrity protection key, CP integrity protection key, UP encryption / ciphering key, CP encryption / ciphering key). In this example, the UE derives (and possibly stores) the security keys before the LTM cell switch execution i.e. before it receives the LTM cell switch command. Later, the UE receives the LTM cell switch command, indicating that LTM candidate cell e.g. based on lower layer measurements the UE has performed on the LTM candidate cell and reports to the network (e.g. reports including Reference Symbol Received Power / Reference Signal Received Power (RSRP) and / or Reference Signal Received Quality / Reference Symbol Received Quality (RSRQ) for beam(s) and / or Synchronization Signal Blocks (SSBs) and / or Channel State Information Reference Signal CSLRS(s) of the LTM candidate cell(s)). Since the security keys have already been derived by the UE for that LTM candidate cell before the reception of the LTM cell switch command, the UE reduces the delay in the LTM cell switch procedure i.e. the interruption time may be reduced in the LTM cell switch procedure. Thanks to the fact that the UE has derived the one or more security keys for that LTM candidate cell in advance, e.g. upon reception of the reconfiguration message including the security information about the LTM candidate cell, either at the reception or between the reception of the reconfiguration and the LTM cell switch command, the interruption time in the inter-CU LTM cell switch procedure is reduced, compared to the legacy handover (in which the UE needs to perform the handover execution at the time it receives the handover command).

[0161] When the UE receives the LTM cell switch command for the LTM candidate cell, the UE uses the one or more security keys for the LTM candidate cell (previously derived before reception of the LTM cell switch command) upon reception of the LTM cell switch command indicating an LTM candidate cell. In other words, the UE applies the provided ciphering algorithm and security key during an PDCP entity re-establishment procedure and / or the UE applies the provided integrity protection algorithm and key during an PDCP entity reestablishment procedure.

[0162] In certain embodiments of the present disclosure, when the UE is configured with multiple LTM candidate cells, the UE derives security keys associated to each LTM candidate cell. After, when the UE receives the LTM cell switch command indicating one of the multiple LTM candidate cells, the UE uses the security keys for the indicated LTM candidate cell, and discards (releases, deletes it) the other sets of security keys for the other LTM candidate cell(s).

[0163] In an alternative embodiment, the security key(s) of the other candidate(s) are not discarded but are stored, in case the UE needs to perform sub-sequent LTM cell switch.

[0164] In other alternative embodiments, the security key(s) of the other candidate(s) are not discarded but are updated, considering that these are still valid candidates after the UE moves to the cell indicated in the LTM cell switch command.Sequence diagrams

[0165] The following section includes a number of sequence diagrams illustrating signalling according to the methods described above.

[0166] Figure 8 illustrates a message sequence chart according to an embodiment of the disclosure. In this embodiment, the UE 802 receives from the source (first) gNB 804 an LTM configuration including a measurement configuration and at least one inter-CU LTM candidate cell configuration created by the target (second) gNB 806.

[0167] Referring to Figure 8, the main steps in this embodiment are as follows.Step 808: The first gNB 804 receives, from the UE 802, an L3 measurement report message, such as an MeasurementReport RRC message. The message contains measurements of at least an inter-CU LTM candidate cell.Step 810: The first gNB 804 decides to perform the configuration of inter-CU LTM candidate cell(s).Step 812: The first gNB 804 transmits, to the second gNB 806, a request message to perform LTM configuration of at least one inter-CU LTM candidate cell. In this example, the message is a HANDOVER REQUEST message.Step 814: The second gNB 806 creates at least one inter-CU LTM candidate cell configuration.Step 816: The second gNB 806 transmits, to the first gNB 804, a response message including at least one inter-CU LTM candidate cell configuration. In this example, the message is a HANDOVER REQUEST ACKNOWLEDGE message.Step 818: The first gNB 804 transmits, to the UE 802, a reconfiguration message, such as an RRCReconfiguration message, including an LTM configuration including a measurement configuration and at least one inter-CU LTM candidate cell configuration. In one example, the measurement configuration includes an indication to perform measurements on the received inter-CU LTM candidate cell(s).Step 820: The UE 802 stores the received LTM configuration.Step 822: The UE 802 transmits, to the first gNB 804, a response message, such as an RRCReconfigurationComplete message to confirm that the LTM configuration has been received.Step 824: The UE 802 performs LI measurements on LTM candidate cells, including the inter-CU candidate cells, according to the received LTM configuration and transmits lower-layer measurement reports to the first gNB 804.

[0168] Figure 9 illustrates a message sequence chart according to an embodiment of the disclosure. In this embodiment, the inter-CU LTM candidate cell configuration procedure is shown, where both the source gNB and target gNB uses a distributed CU / DU RAN architecture.

[0169] Referring to Figure 9, the main steps in this embodiment are as follows.Step 912: The source DU 902 in the first gNB receives, from the UE 904, an L3 measurement report message, such as an MeasurementReport RRC message. The message contains measurements of at least an inter-CU LTM candidate cell.Step 914: The source DU 902 forwards the L3 measurement report to the source CU 906.Step 916: The source CU 906 decides to perform the configuration of at least an inter- CU LTM candidate cell.Step 918: The source CU 906 transmits to the target CU 908 in the second gNB, a request message to perform the LTM configuration of at least an inter-CU LTM candidate cell. In this example, the message is a HANDOVER REQUEST message.Step 920: The target CU 908 sends a request message to the target DU 910 containing the inter-CU LTM candidate cell(s), In this example, the message is a UE CONTEXT SETUP REQUEST message or a LTM request message.Step 922: If the target DU 910 accepts the request of LTM configuration, it provides at least one inter-CU LTM candidate cell configuration using, for example, the UE 904 CONTEXT SETUP RESPONSE message or a LTM response message.Step 924: The target CU 908 sends at least one inter-CU LTM candidate cell configuration to the source CU 906 using the HANDOVER REQUEST ACKNOWLEDGE message.Step 926: The source CU 906 prepares the RRCReconfiguration message including an LTM configuration with a measurement configuration and the inter-CU LTM candidate cell(s) configuration and sends it to the source DU 902.Step 928: The source DU 902 sends to the UE 904 the RRCReconfiguration message including an LTM configuration with a measurement configuration and the inter-CU LTM candidate cell(s) configuration. In one example, the measurement configuration includes an indication to perform measurements on the received inter-CU LTM candidate cell(s).Step 930: The UE 904 stores the received LTM configuration.Step 932-934: The UE 904 completes the reconfiguration procedure by sending the RRCReconfigurationComplete message to the source DU 902, and the source DU 902 forwards it to the Source CU 906.Step 936: The UE 904 performs LI measurements on LTM candidate cells, including the inter-CU candidate cells, according to the received LTM configuration and transmits lower-layer measurement reports to the source DU 902.

[0170] Figure 10 illustrates a flow chart with the steps performed by the UE in an embodiment according to the disclosure.

[0171] Referring to Figure 10, the main steps performed by the UE in this embodiment are as follows:Step 1002: The UE receives, from a first network node, an LTM configuration including a measurement configuration and one or multiple LTM candidate cell configuration(s). At least one of these LTM candidate cell configuration(s) is an inter-CU LTM candidate cell configuration. The UE receives security key parameters update and an indication to perform a security key refresh. In one example, the measurement configuration includes an indication to perform measurements on the received inter-CU LTM candidate cell(s).Step 1004: The UE transmits, to the first network node, a response message to confirm it has received and stored the LTM configuration.Step 1006: The UE performs LI measurements on the LTM candidate cells, including the inter-CU LTM candidate cells according to the received LTM configuration and transmits lower-layer measurement reports to the first network node.

[0172] Below an implementation in the 3GPP XnAP specification, TS 38.423 vl7.4.0, is illustrated for an embodiment according to the disclosure (new text is underlined) The implementation involves the procedures shown in Figures 11 and 12, which illustrate signaling between a source NG-RAN node 1102, 1202 and a target NG-RAN node 1104, 1204.

[0173] In Figure 11, the source NG-RAN node 1102 transmits (at step 1106), to the target NG- RAN node 1104, a handover request message. In response, the target NG-RAN node 1104 transmits (at step 1108), to the source NG-RAN node 1102, a handover request acknowledge message.

[0174] In Figure 12, the source NG-RAN node 1202 transmits (at step 1206), to the target NG- RAN node 1204, a handover request message. In response, the target NG-RAN node 1204 transmits (at step 1208), to the source NG-RAN node 1202, a handover preparation failure message.8.2 Basic mobility procedures8.2.1 Handover PreparationThis procedure is used to establish necessary resources in an NG-RAN node for an incoming handover. If the procedure concerns a conditional handover, parallel transactions are allowed. Possible parallel requests are identified by the target cell ID when the source UE AP IDs are the same.The procedure uses UE-associated signalling.[Text omitted]If the LTM Information Request IE is contained in the HANDOVER REQUEST message, the target NG-RAN node 1104 shall consider that the request concerns L1 / L2 triggered mobility and shall include the LTM Information Acknowledge IE in the HANDOVER REQUEST ACKNOWLEDGE message.If the Target NG-RAN node UE XnAP ZD IE is contained in the LTM Information Request IE included in the HANDOVER REQUEST message, then the target NG- RAN node 1104 shall remove the existing prepared conditional HO identified by theTarget NG-RAN node UE XnAP ID IE and the Target Cell Global ID IE, It is up to the implementation of the target NG-RAN node 1104 when to remove the HO information.If the Maximum Number of LTM Preparations IE is included in the LTM Information Acknowledge IE contained in the HANDOVER REQUEST ACKNOWLEDGE message, then the source NG-RAN node 1102 should not prepare more candidate target cells for a L1 / L2 triggered mobility for the same UE towards the target NG-RAN node 1104 than the number indicated in the IE,If the LTM Information Request IE is contained in the HANDOVER REQUEST message and the target NG-RAN node 1204 rejects the handover or a failure occurs during the Handover Preparation, the target NG-RAN node 1204 shall include the Requested Target Cell ID IE in the HANDOVER PREPARATION FAILURE message.[Text omitted]If the LTM trigger IE is set to “LTM-replace” in the HANDOVER REQUEST message, but there is no LTM prepared for the included Target NG-RAN node UE XnAP ID, or the candidate cell in the Target Cell ID IE was not prepared using the same UE-associated signaling connection, the NG-RAN node 1204 shall reject the procedure using the HANDOVER PREPARATION FAILURE message. .1.1 HANDOVER REQUESTThis message is sent by the source NG-RAN node to the target NG-RAN node to request the preparation of resources for a handover.Direction: source NG-RAN node target NG-RAN node.9.1.1.2 HANDOVER REQUEST ACKNOWLEDGEThis message is sent by the target NG-RAN node to inform the source NG-RAN node about the prepared resources at the target.Direction: target NG-RAN nodesource NG-RAN node.This IE indicates the maximum number of concurrently prepared LTM candidate cells for a UE at a candidate target NG-RAN node.

[0175] Figure 13 shows an example of a communication system 1300 in accordance with some embodiments.

[0176] In the example, the communication system 1300 includes a telecommunication network 1302 that includes an access network 1304, such as a radio access network (RAN), and a core network 1306, which includes one or more core network nodes 1308. The access network 1304 includes one or more access network nodes, such as network nodes 1310a and 1310b (one or more of which may be generally referred to as network nodes 1310), or any other similar 3rdGeneration Partnership Project (3 GPP) 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 1302 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 1302 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 morefunctionalities of any node in the telecommunication network 1302, including one or more network nodes 1310 and / or core network nodes 1308.

[0177] 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 Al, Fl, Wl, El, 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 0-RAN Alliance or comparable technologies. The network nodes 1310 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 1312a, 1312b, 1312c, and 1312d (one or more of which may be generally referred to as UEs 1312) to the core network 1306 over one or more wireless connections.

[0178] 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 1300 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 1300 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0179] The UEs 1312 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 1310 and other communication devices. Similarly, the network nodes 1310 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 1312 and / or with other network nodes or equipment in the telecommunication network1302 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 1302.

[0180] In the depicted example, the core network 1306 connects the network nodes 1310 to one or more hosts, such as host 1316. 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 1306 includes one more core network nodes (e.g., core network node 1308) 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 1308. 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), and / or a User Plane Function (UPF).

[0181] The host 1316 may be under the ownership or control of a service provider other than an operator or provider of the access network 1304 and / or the telecommunication network 1302, and may be operated by the service provider or on behalf of the service provider. The host 1316 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.

[0182] As a whole, the communication system 1300 of Figure 13 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 communicationstandard, 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.

[0183] In some examples, the telecommunication network 1302 is a cellular network that implements 3 GPP standardized features. Accordingly, the telecommunications network 1302 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 1302. For example, the telecommunications network 1302 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) / Massive loT services to yet further UEs.

[0184] In some examples, the UEs 1312 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 1304 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 1304. 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).

[0185] In the example illustrated in Figure 13, the hub 1314 communicates with the access network 1304 to facilitate indirect communication between one or more UEs (e.g., UE 1312c and / or 1312d) and network nodes (e.g., network node 1310b). In some examples, the hub 1314 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 1314 may be a broadband router enabling access to the core network 1306 for the UEs. As another example, the hub 1314 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 1310, or by executable code, script, process, or other instructions in the hub 1314. As another example, the hub 1314 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 1314 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub 1314 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 1314 then provides to the UE either directly, after performing local processing, and / or after addingadditional local content. In still another example, the hub 1314 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0186] The hub 1314 may have a constant / persistent or intermittent connection to the network node 1310b. The hub 1314 may also allow for a different communication scheme and / or schedule between the hub 1314 and UEs (e.g., UE 1312c and / or 1312d), and between the hub 1314 and the core network 1306. In other examples, the hub 1314 is connected to the core network 1306 and / or one or more UEs via a wired connection. Moreover, the hub 1314 may be configured to connect to an M2M service provider over the access network 1304 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 1310 while still connected via the hub 1314 via a wired or wireless connection. In some embodiments, the hub 1314 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 1310b. In other embodiments, the hub 1314 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 1310b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0187] Figure 14 shows a UE 1400 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 the3rd Generation Partnership Project (3GPP), including a narrow band internet of things (NB-IoT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0188] A UE may support device-to-device (D2D) communication, for example by implementing a 3 GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), orvehicle- 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 adevice 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).

[0189] The UE 1400 includes processing circuitry 1402 that is operatively coupled via a bus 1404 to an input / output interface 1406, a power source 1408, a memory 1410, a communication interface 1412, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 14. 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.

[0190] The processing circuitry 1402 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 1410. The processing circuitry 1402 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 1402 may include multiple central processing units (CPUs). The processing circuitry 1402 may be operable to provide, either alone or in conjunction with other UE 1400 components, such as the memory 1410, UE 1400 functionality. For example, the processing circuitry 1402 may be configured to cause the UE 1402 to perform the methods as described with reference to Figure 5.

[0191] In the example, the input / output interface 1406 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 1400. 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 thelike. 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.

[0192] In some embodiments, the power source 1408 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 1408 may further include power circuitry for delivering power from the power source 1408 itself, and / or an external power source, to the various parts of the UE 1400 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 1408. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 1408 to make the power suitable for the respective components of the UE 1400 to which power is supplied.

[0193] The memory 1410 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 1410 includes one or more application programs 1414, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 1416. The memory 1410 may store, for use by the UE 1400, any of a variety of various operating systems or combinations of operating systems.

[0194] The memory 1410 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 (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘ SIMcard.’ The memory 1410 may allow the UE 1400 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 1410, which may be or comprise a device-readable storage medium.

[0195] The processing circuitry 1402 may be configured to communicate with an access network or other network using the communication interface 1412. The communication interface 1412 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1422. The communication interface 1412 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 1418 and / or a receiver 1420 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 1418 and receiver 1420 may be coupled to one or more antennas (e.g., antenna 1422) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0196] In some embodiments, communication functions of the communication interface 1412 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 / intemet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0197] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 1412, 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 issent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0198] 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.

[0199] 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 1400 shown in Figure 14.

[0200] 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 3 GPP NB-IoT 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.

[0201] 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.

[0202] Figure 15 shows a network node 1500 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 NRNodeBs (gNBs)), 0-RAN nodes or components of an 0-RAN node (e.g, 0-RU, 0-DU, O-CU).

[0203] 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 0-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).

[0204] 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).

[0205] The network node 1500 includes processing circuitry 1502, a memory 1504, a communication interface 1506, and a power source 1508, and / or any other component, or any combination thereof. The network node 1500 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 1500 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 1500 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 1504 for different RATs) and some components may be reused (e.g., a same antenna 1510 may be shared by different RATs). The network node 1500 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1500, 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 1500.

[0206] The processing circuitry 1502 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 1500 components, such as the memory 1504, network node 1500 functionality. For example, the processing circuitry 1502 may be configured to cause the network node to perform the methods as described with reference to Figure 6 or 7

[0207] In some embodiments, the processing circuitry 1502 includes a system on a chip (SOC). In some embodiments, the processing circuitry 1502 includes one or more of radio frequency (RF) transceiver circuitry 1512 and baseband processing circuitry 1514. In some embodiments, the radio frequency (RF) transceiver circuitry 1512 and the baseband processing circuitry 1514 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 1512 and baseband processing circuitry 1514 may be on the same chip or set of chips, boards, or units.

[0208] The memory 1504 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 1502. The memory 1504 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 1502 and utilized by the network node 1500. The memory 1504 may be used to store any calculations made by the processing circuitry 1502 and / or any data received via the communication interface 1506. In some embodiments, the processing circuitry 1502 and memory 1504 is integrated.

[0209] The communication interface 1506 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 1506 comprises port(s) / terminal(s) 1516 to send and receive data, for example to and from a network over a wired connection. The communication interface 1506 also includes radio front-end circuitry 1518 that may be coupled to, or in certain embodiments a part of, the antenna 1510. Radio front-end circuitry 1518 comprises filters 1520 and amplifiers 1522. The radio front-end circuitry 1518 may be connected to an antenna 1510 and processing circuitry 1502. The radio front-end circuitry may be configured to condition signals communicated between antenna 1510 and processing circuitry 1502. The radio front-end circuitry 1518 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 1518 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1520 and / or amplifiers 1522. The radio signal may then be transmitted via the antenna 1510. Similarly, when receiving data, the antenna 1510 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1518. The digital data may be passed to the processing circuitry 1502. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0210] In certain alternative embodiments, the network node 1500 does not include separate radio front-end circuitry 1518, instead, the processing circuitry 1502 includes radio front-endcircuitry and is connected to the antenna 1510. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1512 is part of the communication interface 1506. In still other embodiments, the communication interface 1506 includes one or more ports or terminals 1516, the radio front-end circuitry 1518, and the RF transceiver circuitry 1512, as part of a radio unit (not shown), and the communication interface 1506 communicates with the baseband processing circuitry 1514, which is part of a digital unit (not shown).

[0211] The antenna 1510 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1510 may be coupled to the radio front-end circuitry 1518 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1510 is separate from the network node 1500 and connectable to the network node 1500 through an interface or port.

[0212] The antenna 1510, communication interface 1506, and / or the processing circuitry 1502 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 1510, the communication interface 1506, and / or the processing circuitry 1502 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.

[0213] The power source 1508 provides power to the various components of network node 1500 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1508 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1500 with power for performing the functionality described herein. For example, the network node 1500 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 1508. As a further example, the power source 1508 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.

[0214] Embodiments of the network node 1500 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 tosupport the subject matter described herein. For example, the network node 1500 may include user interface equipment to allow input of information into the network node 1500 and to allow output of information from the network node 1500. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1500.

[0215] Figure 16 is a block diagram of a host 1600, which may be an embodiment of the host 1316 of Figure 13, in accordance with various aspects described herein. As used herein, the host 1600 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 1600 may provide one or more services to one or more UEs.

[0216] The host 1600 includes processing circuitry 1602 that is operatively coupled via a bus 1604 to an input / output interface 1606, a network interface 1608, a power source 1610, and a memory 1612. 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 14 and 15, such that the descriptions thereof are generally applicable to the corresponding components of host 1600.

[0217] The memory 1612 may include one or more computer programs including one or more host application programs 1614 and data 1616, which may include user data, e.g., data generated by a UE for the host 1600 or data generated by the host 1600 for a UE. Embodiments of the host 1600 may utilize only a subset or all of the components shown. The host application programs 1614 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (VVC), 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 1614 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 1600 may select and / or indicate a different host for over-the-top services for a UE. The host application programs 1614 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.

[0218] Figure 17 is a block diagram illustrating a virtualization environment 1700 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 1700 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 1700 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an O-2 interface.

[0219] Applications 1702 (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.

[0220] Hardware 1704 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 1706 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1708a and 1708b (one or more of which may be generally referred to as VMs 1708), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 1706 may present a virtual operating platform that appears like networking hardware to the VMs 1708.

[0221] The VMs 1708 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1706. Different embodiments of the instance of a virtual appliance 1702 may be implemented on one or more of VMs 1708, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFVmay 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.

[0222] In the context of NFV, a VM 1708 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 1708, and that part of hardware 1704 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 1708 on top of the hardware 1704 and corresponds to the application 1702.

[0223] Hardware 1704 may be implemented in a standalone network node with generic or specific components. Hardware 1704 may implement some functions via virtualization. Alternatively, hardware 1704 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 1710, which, among others, oversees lifecycle management of applications 1702. In some embodiments, hardware 1704 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 1712 which may alternatively be used for communication between hardware nodes and radio units.

[0224] Figure 18 shows a communication diagram of a host 1802 communicating via a network node 1804 with a UE 1806 over a partially wireless connection in accordance with some embodiments. Example implementations, in accordance with various embodiments, of the UE (such as aUE 1312a ofFigure 13 and / or UE 1400 ofFigure 14), network node (such as network node 1310a ofFigure 13 and / or network node 1500 ofFigure 15), and host (such as host 1316 ofFigure 13 and / or host 1600 ofFigure 16) discussed in the preceding paragraphs will now be described with reference to Figure 18.

[0225] Like host 1600, embodiments of host 1802 include hardware, such as a communication interface, processing circuitry, and memory. The host 1802 also includes software, which is stored in or accessible by the host 1802 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 1806 connecting via an over-the-top (OTT) connection 1850 extending between the UE 1806 and host 1802. In providing the service to the remote user, a host application may provide user data which is transmitted using the OTT connection 1850.

[0226] The network node 1804 includes hardware enabling it to communicate with the host 1802 and UE 1806. The connection 1860 may be direct or pass through a core network (like core network 1306 of Figure 13) 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.

[0227] The UE 1806 includes hardware and software, which is stored in or accessible by UE 1806 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 1806 with the support of the host 1802. In the host 1802, an executing host application may communicate with the executing client application via the OTT connection 1850 terminating at the UE 1806 and host 1802. In providing the service to the user, th’ UE's client application may receive request data from the ’ost's host application and provide user data in response to the request data. The OTT connection 1850 may transfer both the request data and the user data. Th’ 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 1850.

[0228] The OTT connection 1850 may extend via a connection 1860 between the host 1802 and the network node 1804 and via a wireless connection 1870 between the network node 1804 and the UE 1806 to provide the connection between the host 1802 and the UE 1806. The connection 1860 and wireless connection 1870, over which the OTT connection 1850 may be provided, have been drawn abstractly to illustrate the communication between the host 1802 and the UE 1806 via the network node 1804, without explicit reference to any intermediary devices and the precise routing of messages via these devices.

[0229] As an example of transmitting data via the OTT connection 1850, in step 1808, the host 1802 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 1806. In other embodiments, the user data is associated with a UE 1806 that shares data with the host 1802 without explicit human interaction. In step 1810, the host 1802 initiates a transmission carrying the user data towards the UE 1806. The host 1802 may initiate the transmission responsive to a request transmitted by the UE 1806. The request may be causedby human interaction with the UE 1806 or by operation of the client application executing on the UE 1806. The transmission may pass via the network node 1804, in accordance with the teachings of the embodiments described throughout this disclosure. Accordingly, in step 1812, the network node 1804 transmits to the UE 1806 the user data that was carried in the transmission that the host 1802 initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1814, the UE 1806 receives the user data carried in the transmission, which may be performed by a client application executed on the UE 1806 associated with the host application executed by the host 1802.

[0230] In some examples, the UE 1806 executes a client application which provides user data to the host 1802. The user data may be provided in reaction or response to the data received from the host 1802. Accordingly, in step 1816, the UE 1806 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 1806. Regardless of the specific manner in which the user data was provided, the UE 1806 initiates, in step 1818, transmission of the user data towards the host 1802 via the network node 1804. In step 1820, in accordance with the teachings of the embodiments described throughout this disclosure, the network node 1804 receives user data from the UE 1806 and initiates transmission of the received user data towards the host 1802. In step 1822, the host 1802 receives the user data carried in the transmission initiated by the UE 1806.

[0231] One or more of the various embodiments improve the performance of OTT services provided to the UE 1806 using the OTT connection 1850, in which the wireless connection 1870 forms the last segment. More precisely, the teachings of these embodiments may improve the latency and thereby provide benefits such as reduced user waiting time.

[0232] In an example scenario, factory status information may be collected and analyzed by the host 1802. As another example, the host 1802 may process audio and video data which may have been retrieved from a UE for use in creating maps. As another example, the host 1802 may collect and analyze real-time data to assist in controlling vehicle congestion (e.g., controlling traffic lights). As another example, the host 1802 may store surveillance video uploaded by a UE. As another example, the host 1802 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 1802 may be used for energy pricing, remote control of non-time critical electrical load to balance power generation needs, location services, presentationservices (such as compiling diagrams etc. from data collected from remote devices), or any other function of collecting, retrieving, storing, analyzing and / or transmitting data.

[0233] 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 1850 between the host 1802 and UE 1806, 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 1802 and / or UE 1806. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which the OTT connection 1850 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 1850 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not directly alter the operation of the network node 1804. 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 1802. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 1850 while monitoring propagation times, errors, etc.

[0234] 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, andfunctionality 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.

[0235] 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.

[0236] The following groups of statements set out embodiments of the disclosure.Group A Embodiments1. A method performed by a user equipment, the method comprising: receiving, from a network node, a configuration for use in connecting to and / or communicating with a candidate cell following a lower-layer cell mobility procedure, wherein the configuration comprises information that enables the user equipment to refresh one or more security keys for use in connecting to and / or communicating with the candidate cell.2. The method of embodiment 1, further comprising: upon executing the lower-layer cell mobility procedure to the candidate cell, using the information to determine one or more security keys; and using the one or more security keys to connect to and / or communicate with the candidate cell.3. The method of embodiment 1, further comprising:prior to executing the lower-layer cell mobility procedure to the candidate cell, using the information to determine one or more security keys; and upon executing the lower-layer cell mobility procedure, using the one or more security keys to connect to and / or communicate with the candidate cell. The method of embodiment 3, wherein the user equipment uses the information to determine the one or more security keys upon reception of the configuration. The method of any one of the preceding embodiments, wherein the configuration further comprises a measurement configuration comprising an instruction for the user equipment to perform measurements on transmissions by the candidate cell. The method of embodiment 5, further comprising transmitting a report message to the network node, comprising an indication of values derived from the measurements on transmissions by the candidate cell. The method of any one of the preceding embodiments, wherein the configuration comprises an indication of one or more source cells, and wherein the user equipment determines whether to refresh the one or more security keys based on whether or not the lower-layer mobility procedure was from one of the one or more source cells. The method of embodiment 7, wherein the indication of one or more source cells comprises one or more of: one or more cell IDs; one or more physical cell identifiers; one or more source cell configuration identifiers; and an identifier of a group of one or more cells. The method of any one of the preceding embodiments, wherein the configuration comprises one of: a full configuration; and a delta configuration defining one or more differences relative to a reference configuration. The method of any one of the preceding embodiments, wherein the network node comprises a first centralized unit, CU, or a first base station, and wherein the candidate cell is served by a second CU or a second base station.11. The method of any one of the preceding embodiments, wherein the information that enables the user equipment to refresh one or more security keys comprises one or more of: an indication of a master key update parameter; an indication of one or more security algorithms to be used by the user equipment to derive one or more user plane keys and / or one or more control plane keys.12. The method of any one of the preceding embodiments, wherein the one or more security keys comprise a master key for a network node serving the candidate cell.13. The method of any one of the preceding embodiments, further comprising: receiving, via lower-layer signalling from a source network node, a command to switch to the candidate cell.14. The method of embodiment 13, wherein the command comprises an indication that the candidate cell is served by a different CU or a different base station than the source network node.15. The method of any one of embodiments 13 to 14, wherein the lower-layer signalling comprises one or more of: LI and L2 signalling.16. The method of any one of embodiments 13 to 15, wherein the lower-layer signalling comprises one or more of: Medium Access Control, MAC, signalling and Physical, PHY, layer signalling.17. The method according to any one of the preceding embodiments, wherein the lower- layer cell mobility procedure comprises an L1 / L2 triggered mobility, LTM, procedure.18. 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 Embodiments19. A method performed by a network node, the method comprising:transmitting, to a user equipment, a configuration for use in connecting to and / or communicating with a candidate cell following a lower-layer cell mobility procedure, wherein the configuration comprises information that enables the user equipment to refresh one or more security keys for use in connecting to and / or communicating with the candidate cell. The method of embodiment 19, wherein the configuration further comprises a measurement configuration comprising an instruction for the user equipment to perform measurements on transmissions by the candidate cell. The method of embodiment 20, further comprising receiving a report message from the user equipment, comprising an indication of values derived from the measurements on transmissions by the candidate cell. The method of any one of embodiments 19 to 21, wherein the configuration comprises an indication of one or more source cells, for use by the user equipment in determining whether to refresh the one or more security keys based on whether or not the lower-layer mobility procedure was from one of the one or more source cells. The method of embodiment 22, wherein the indication of one or more source cells comprises one or more of one or more cell IDs; one or more physical cell identifiers; one or more source cell configuration identifiers; and an identifier of a group of one or more cells. The method of any one of embodiments 19 to 23, wherein the configuration comprises one of a full configuration; and a delta configuration defining one or more differences relative to a reference configuration. The method of any one of embodiments 19 to 24, wherein the network node comprises a first centralized unit, CU, or a first base station, and wherein the candidate cell is served by a second CU or a second base station. The method of any one of embodiments 19 to 25, wherein the information that enables the user equipment to refresh one or more security keys comprises one ormore of: an indication of a master key update parameter; an indication of one or more security algorithms to be used by the user equipment to derive one or more user plane keys and / or one or more control plane keys. The method of any one of embodiments 19 to 26, wherein the one or more security keys comprise a master key for a network node serving the candidate cell. The method of any one of embodiments 19 to 27, further comprising: transmitting, via lower-layer signalling to the user equipment, a command to switch to the candidate cell. The method of embodiment 28, wherein the command comprises an indication that the candidate cell is served by a different CU or a different base station than the source network node. The method of any one of embodiments 28 to 29, wherein the lower-layer signalling comprises one or more of: LI and L2 signalling. The method of any one of embodiments 28 to 30, wherein the lower-layer signalling comprises one or more of: Medium Access Control, MAC, signalling and Physical, PHY, layer signalling. The method according to any one of embodiments 19 to 31, wherein the lower-layer cell mobility procedure comprises an L1 / L2 triggered mobility, LTM, procedure. The method according to any one of embodiments 19 to 32, further comprising: transmitting a request message to a second network node, comprising a request for the second network node to transmit the configuration for use in connecting to and / or communicating with the candidate cell following the lower-layer cell mobility procedure. The method according to embodiment 33, wherein the request message comprises a handover request message. The method according to embodiment 33 or 34, wherein the request messagecomprises a request for the second network node to transmit a plurality of configurations for a plurality of candidate cells served by the second network node.36. The method according to any one of embodiments 33 to 35, further comprising receiving, from the second network node, the configuration for use in connecting to and / or communicating with the candidate cell following the lower-layer cell mobility procedure.37. 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.38. A method performed by a second network node, the method comprising: receiving, from a first network node, a request message comprising a request for the second network node to transmit a configuration for use by a user equipment in connecting to and / or communicating with a candidate cell served by the second network node following the lower-layer cell mobility procedure.39. The method according to embodiment 38, wherein the request message comprises a handover request message.40. The method according to embodiment 38 or 39, wherein the request message comprises a request for the second network node to transmit a plurality of configurations for a plurality of candidate cells served by the second network node.41. The method according to any one of embodiments 38 to 40, further comprising transmitting, to the first network node, the configuration for use in connecting to and / or communicating with the candidate cell following the lower-layer cell mobility procedure.Group C Embodiments42. A user equipment, 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.43. 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.44. A user equipment (UE), 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.45. 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.46. 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.47. 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.48. The method of the previous embodiment, further comprising, at the network node, transmitting the user data provided by the host for the UE.49. 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.50. 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.51. The communication system of the previous embodiment, further comprising: the network node; and / or the UE.52. 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.53. 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.54. The host of the any of the previous 2 embodiments, wherein the initiating receipt of the user data comprises requesting the user data.55. 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.56. The method of the previous embodiment, further comprising at the network node,transmitting the received user data to the host.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 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.58. 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.59. 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.60. 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.61. The method of the previous embodiment, further comprising: at the host, executing a host application associated with a client application executingon the UE to receive the user data from the host application.62. 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.63. 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.64. 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.65. 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.66. 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.67. 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.68. The method of the previous 2 embodiments, 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.

Claims

CLAIMS1. A method performed by a user equipment, the method comprising: receiving (502), from a network node, a configuration for use in connecting to and / or communicating with a candidate cell following a lower-layer cell mobility procedure, wherein the configuration comprises information that enables the user equipment to refresh one or more security keys for use in connecting to and / or communicating with the candidate cell.

2. The method of claim 1, further comprising: upon executing the lower-layer cell mobility procedure to the candidate cell, using the information to determine (508) one or more security keys; and using (510) the one or more security keys to connect to and / or communicate with the candidate cell.

3. The method of claim 1, further comprising: prior to executing the lower-layer cell mobility procedure to the candidate cell, using the information to determine (508) one or more security keys; and upon executing the lower-layer cell mobility procedure, using (510) the one or more security keys to connect to and / or communicate with the candidate cell.

4. The method of any one of the preceding claims, wherein the configuration further comprises a measurement configuration comprising an instruction for the user equipment to perform measurements on transmissions by the candidate cell.

5. The method of any one of the preceding claims, wherein the configuration comprises an indication of one or more source cells, and wherein the user equipment determines whether to refresh the one or more security keys based on whether or not the lower- layer mobility procedure was from one of the one or more source cells.

6. The method of any one of the preceding claims, wherein the network node comprises a first centralized unit, CU, or a first base station, and wherein the candidate cell is served by a second CU or a second base station.

7. The method of any one of the preceding claims, wherein the information that enables the user equipment to refresh one or more security keys comprises one or more of: an indication of a master key update parameter; an indication of one or more security algorithms to be used by the user equipment to derive one or more user plane keys and / or one or more control plane keys.

8. The method of any one of the preceding claims, wherein the one or more security keys comprise a master key for a network node serving the candidate cell.

9. The method of any one of the preceding claims, further comprising: receiving (506), via lower-layer signalling from a source network node, a command to switch to the candidate cell.

10. The method of claim 9, wherein the command comprises an indication that the candidate cell is served by a different CU or a different base station than the source network node.

11. The method according to any one of the preceding embodiments, wherein the lower- layer cell mobility procedure comprises an L1 / L2 triggered mobility, LTM, procedure.

12. A method performed by a network node, the method comprising: transmitting (606), to a user equipment, a configuration for use in connecting to and / or communicating with a candidate cell following a lower-layer cell mobility procedure, wherein the configuration comprises information that enables the user equipment to refresh one or more security keys for use in connecting to and / or communicating with the candidate cell.

13. The method of claim 12, wherein the configuration further comprises a measurement configuration comprising an instruction for the user equipment to perform measurements on transmissions by the candidate cell.

14. The method of any one of claims 12 to 13, wherein the configuration comprises anindication of one or more source cells, for use by the user equipment in determining whether to refresh the one or more security keys based on whether or not the lower- layer mobility procedure was from one of the one or more source cells.

15. The method of any one of claims 12 to 14, wherein the network node comprises a first centralized unit, CU, or a first base station, and wherein the candidate cell is served by a second CU or a second base station.

16. The method of any one of claims 12 to 15, wherein the information that enables the user equipment to refresh one or more security keys comprises one or more of: an indication of a master key update parameter; an indication of one or more security algorithms to be used by the user equipment to derive one or more user plane keys and / or one or more control plane keys.

17. The method of any one of claims 12 to 16, wherein the one or more security keys comprise a master key for a network node serving the candidate cell.

18. The method of any one of claims 12 to 17, further comprising: transmitting (610), via lower-layer signalling to the user equipment, a command to switch to the candidate cell.

19. The method of claim 18, wherein the command comprises an indication that the candidate cell is served by a different CU or a different base station than the source network node.

20. The method according to any one of claims 12 to 19, wherein the lower-layer cell mobility procedure comprises an L1 / L2 triggered mobility, LTM, procedure.

21. The method according to any one of claims 12 to 20, further comprising: transmitting (602) a request message to a second network node, comprising a request for the second network node to transmit the configuration for use in connecting to and / or communicating with the candidate cell following the lower-layer cell mobility procedure.

22. The method according to claim 21, wherein the request message comprises a handover request message.

23. The method according to claim 21 or 22, wherein the request message comprises a request for the second network node to transmit a plurality of configurations for a plurality of candidate cells served by the second network node.

24. The method according to any one of claims 21 to 23, further comprising receiving (604), from the second network node, the configuration for use in connecting to and / or communicating with the candidate cell following the lower-layer cell mobility procedure.

25. A method performed by a second network node, the method comprising: receiving (702), from a first network node, a request message comprising a request for the second network node to transmit a configuration for use by a user equipment in connecting to and / or communicating with a candidate cell served by the second network node following the lower-layer cell mobility procedure.

26. The method according to claim 25, wherein the request message comprises a handover request message.

27. The method according to claim 25 or 26, wherein the request message comprises a request for the second network node to transmit a plurality of configurations for a plurality of candidate cells served by the second network node.

28. The method according to any one of claims 25 to 27, further comprising transmitting (704), to the first network node, the configuration for use in connecting to and / or communicating with the candidate cell following the lower-layer cell mobility procedure.

29. A user equipment (1400), comprising: processing circuitry (1402) configured to cause the user equipment to receive (502),from a network node, a configuration for use in connecting to and / or communicating with a candidate cell following a lower-layer cell mobility procedure, wherein the configuration comprises information that enables the user equipment to refresh one or more security keys for use in connecting to and / or communicating with the candidate cell.

30. The user equipment of claim 29, the processing circuitry further configured to cause the user equipment to perform the method of any one of claims 2-11.

31. A network node (1500), the network node comprising: processing circuitry (1502) configured to cause the network node to transmit (606), to a user equipment, a configuration for use in connecting to and / or communicating with a candidate cell following a lower-layer cell mobility procedure, wherein the configuration comprises information that enables the user equipment to refresh one or more security keys for use in connecting to and / or communicating with the candidate cell.

32. The network node of claim 31, the processing circuitry further configured to cause the network node to perform the method of any one of claims 13-24.

33. A second network node (1500), the second network node comprising: processing circuitry (1502) configured to cause the second network node to receive (702), from a first network node, a request message comprising a request for the second network node to transmit a configuration for use by a user equipment in connecting to and / or communicating with a candidate cell served by the second network node following the lower-layer cell mobility procedure.

34. The second network node of claim 33, the processing circuitry further configured to cause the second network node to perform the method of any one of claims 26-28.

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