LTM candidate cell CSI configuration and reporting

Abstract

According to some embodiments, a method is performed by a user equipment (UE). The method comprises: obtaining an indication of one or more layer one / layer two triggered mobility (LTM) candidate cells for which the UE is to acquire channel state information (CSI); measuring CSI for the one or more LTM candidate cells; determining to perform an LTM cell switch to a target LTM candidate cell of the one or more LTM candidate cells; and reporting the CSI measurements of the target LTM candidate cell to the target candidate cell.

Description

LTM Candidate Cell CSI Configuration and ReportingTECHNICAL FIELD

[0001] The present disclosure generally relates to communication networks, and more specifically to layer one (Ll) / layer two (L2) triggered mobility (LTM) candidate cell channel state information (CSI) configuration and reporting.BACKGROUND

[0002] Third Generation Partnership Project (3GPP) Release 18 includes layer one (Ll) / layer two (L2) triggered mobility (LTM). LTM is a procedure in which a gNB receives LI measurement report(s) from a user equipment (UE), and on that basis the gNB changes the UE serving cell by a cell switch command signaled via a medium access control (MAC) control element (CE). The cell switch command indicates an LTM candidate configuration that the gNB previously prepared and provided to the UE through Radio Resource Control (RRC) signaling. The UE then switches to the target configuration according to the cell switch command (RP-234036, New WID: NR mobility enhancements Phase 4, 3GPP TSGRAN Meeting #102, Edinburgh, Scotland, December 11-15, 2023).

[0003] When configured by the network, it is possible to activate transmission configuration indicator (TCI) states of one or multiple cells that are different from the current serving cell. This is sometimes referred to as pre-activation of a candidate TCI state, because this is pre-activating a TCI state of an LTM candidate cell before the UE receives the LTM cell switch command, i.e., before the LTM cell switch procedure. For example, the TCI states of the LTM candidate cells may be activated in advance before any of those cells become the serving cell. This enables the UE to be downlink (DL) synchronized with the candidate cells (or DL pre-synchronized), thereby facilitating a faster cell switch to one of the candidate cells when cell switch is triggered. The cell switch command is conveyed in a MAC CE, which contains the necessary information to perform the LTM cell switch.

[0004] Figure l is a flow diagram illustrating the procedure for LTM. The procedure for LTM is as follows:

[0005] At step 1 , UE 200 sends a MeasurementReport message to gNB 300. The gNB decides to configure LTM and initiates LTM preparation.

[0006] At step 2, the gNB transmits an RRCReconfiguration message to the UE including the LTM candidate configurations.

[0007] At step 3, the UE stores the LTM candidate configurations and transmits an RRCReconfigurationComplete message to the gNB.

[0008] At step 4a, the UE performs downlink synchronization with the candidate cell(s) before receiving the cell switch command. This is triggered upon reception by the UE of a “Candidate Cell TCI States Activation / Deactivation MAC CE” for LTM candidate cell(s) configured in CandidateTCI-State and CandidateTCI-UL-State. Upon reception in the UE’s MAC entity, the UE’s MAC entity receives a Candidate Cell TCI States Activation / Deactivation MAC CE on a Serving Cell, the UE indicates to lower layers the information regarding the Candidate Cell TCI States Activation / Deactivation MAC CE.

[0009] At step 4b, the UE may also perform UL pre-synchronization with the LTM candidate cell(s) if the UE receives the physical downlink control channel (PDCCH) order for early timing advance (TA) acquisition for the candidate cells.

[0010] At step 5, the UE performs LI measurements on the configured candidate cell(s) and transmits LI measurement reports to the gNB. LI measurement should be performed as long as RRC reconfiguration (step 2) is applicable.

[0011] At step 6, the gNB decides to execute cell switch to a target cell and transmits a MAC CE triggering cell switch by including the candidate configuration index of the target cell. The UE switches to the target cell and applies the configuration indicated by candidate configuration index.

[0012] At step 7, the UE performs the random-access procedure towards the target cell if the UE does not have a valid TA of the target cell. Otherwise, if the UE receives a valid TA value in LTM cell switch command using early TA acquisition method in step 4b, the UE is not required to perform random-access.

[0013] At step 8, the UE completes the LTM cell switch procedure by sending RRCReconfigurationComplete message to target cell. If the UE has performed a random access (RA) procedure in step 7, the UE considers the LTM cell switch execution is successfully completed when the random-access procedure is successfully completed. For random access channel (RACH)-less LTM, the UE considers the LTM cell switch execution is successfully completed when the UE determines that the network has successfully received its first uplink (UL) data.

[0014] Release 19 supports channel state information reference signal (CSI-RS) measurements for LTM. LTM was introduced in Rel-18 and offers improvements in handover latency and interruption time compared to Layer 3 based mobility. However, LTM as introduced in Rel-18 also has a number of limitations compared to Layer 3 mobility. The Rel-19 work item aims to remove a number of these limitations. The objectives for the Rel. 19 WID “NR mobilityenhancements Phase 4” include measurement related enhancements for purpose of supporting LTM, such as specifying support for CSI-RS measurements for LTM procedures and enable CSI- RS based beam management, and / or other necessary physical layer operations on candidate cells before LTM.

[0015] Conditional handover (CHO) and the related conditional mobility procedures were introduced in New Radio (NR) for improving the mobility robustness by preparing the UE (and the CHO candidate cells) in advance before there are any radio link outages. The UE is provided the RRC configuration of the candidate CHO cells, like LTM, and some CHO execution conditions, which once fulfilled lead the UE to directly perform the handover without sending measurement reports to the network, unlike LTM. However, there are other differences between the legacy CHO and LTM, for example, the CHO does not include the procedure of early synchronization in Rel-18.

[0016] To facilitate both the advantages of short handover interruption as well as better robustness, Rel-19 aims to introduce Conditional LTM as part of the mobility-related enhancements. The following Conditional LTM-related objectives have been agreed upon in NR mobility enhancements phase 4 WI (RP-241515, New WID: NR mobility enhancements Phase 4, 3GPP TSG RAN Meeting #104, Shanghai, China, Juna 17-20, 2024): (a) specify support of conditional LTM; (b) specify UE evaluated conditions for triggering LTM; and (c) support conditional LTM including subsequent LTM.

[0017] In Conditional LTM, the UE is configured with the conditional LTM execution conditions along with the LTM candidate cell configuration. The UE may perform early UL and DL synchronization procedures before the cell switch and shall execute LTM cell switch upon the fulfillment of the provided execution conditions. The Conditional LTM in Rel-19 can also be configured with the subsequent LTM executions, in the same way as the subsequent LTM in Rel- 18.

[0018] There currently exist certain challenges. For example, supporting CSI-RS measurements for LTM procedures could be expected to cause greater throughput on the target cell directly after cell switch. After cell switch, the new serving cell would have to configure the UE with CSI reports and await UE CSI reports before performing link adaptation. During this time, the UE will have reduced UL / DL throughput compared to after CSI has been reported. This reduced performance directly after cell switch is addressed by particular embodiments described herein.SUMMARY

[0019] As described above, certain challenges currently exist with layer one (Ll) / layer two (L2) triggered mobility (LTM) candidate cell channel state information (CSI) configuration and reporting. Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. For example, according to some embodiments, measurements on CSI reference signals (CSI-RS) from a candidate cell may be used to speed up link adaptation in the candidate cell. In particular embodiments, the user equipment (UE) measures CSI for the candidate cell before the LTM cell switch. If the candidate cell has access to the CSI measurements immediately after the LTM cell switch, the network is able to perform link adaptation early during the communication in the target cell.

[0020] The CSI measurements need to be available for the candidate cell. There are essentially two ways of doing this. In one, the UE reports the CSI to the serving cell, which then forwards the CSI to the relevant candidate cell, which uses the CSI after the cell switch. In the second, the UE reports the CSI in one of the first transmissions to the candidate cell. For example, the UE may include the measurements in the same uplink (UL) transmission that includes the RRC reconfiguration complete. These two procedures are illustrated in Figures 2A and 2B.

[0021] Figure 2A is a sequence diagram illustrating a procedure for CSI measurements on a candidate cell before LTM cell switch, where the measurements are forwarded via the serving cell to the candidate cell. Figure 2B is a sequence diagram illustrating a procedure for CSI measurements on a candidate cell before LTM cell switch, where the measurements are transmitted from the UE to the candidate cell.

[0022] Particular embodiments are described with respect to the second approach where the CSI is reported in one of the first transmissions to the candidate cell.

[0023] According to some embodiments, a method is performed by a user equipment. The method comprises: obtaining an indication of one or more LTM candidate cells for which the user equipment is to acquire CSI; measuring CSI for the one or more LTM candidate cells; determining to perform an LTM cell switch to a target LTM candidate cell of the one or more LTM candidate cells; and reporting the CSI measurements of the target LTM candidate cell to the target candidate cell.

[0024] In particular embodiments, obtaining the indication of the one or more LTM candidate cells for which the user equipment is to acquire CSI comprises receiving from a serving cell a CSI configuration.

[0025] In particular embodiments, the CSI configuration comprises an indication that the CSI configuration takes effect upon receipt of the CSI configuration or upon fulfillment of a condition associated with an LTM candidate cell.

[0026] In particular embodiments, the condition comprises any one or more of: the user equipment activates a transmission configuration indicator (TCI) state of the LTM candidate cell; the user equipment is configured with one or more LTM events and when the conditions for an event are fulfilled for the LTM candidate cell or a beam of the LTM candidate cell, it triggers the user equipment to start acquiring CSI for the LTM candidate cell; and the user equipment is configured with at least two conditional LTM execution conditions and one of the conditional LTM execution conditions are satisfied.

[0027] In particular embodiments, the CSI configuration comprises an indication of what CSI quantities to be computed or reported.

[0028] In particular embodiments, reporting the CSI measurements of the target LTM candidate cell to the target candidate cell comprises reporting the CSI measurements in a Radio Resource Control Reconfiguration Complete message.

[0029] In particular embodiments, reporting the CSI measurements of the target LTM candidate cell to the target candidate cell comprises reporting the CSI measurements in an uplink grant provided as part of an LTM cell switch command.

[0030] According to some embodiments, a user equipment comprises processing circuitry operable to perform any of the user equipment methods described above.

[0031] According to some embodiments, a method is performed by a source network node. The method comprises: obtaining a CSI configuration from one or more LTM candidate cells; transmitting the CSI configuration to a user equipment; and transmitting an LTM cell switch command for one of the one or more LTM candidate cells to the user equipment.

[0032] In particular embodiments, the CSI configuration comprises an indication that the CSI configuration takes effect upon receipt of the CSI configuration or upon fulfillment of a condition associated with the LTM candidate cell.

[0033] In particular embodiments, the condition comprises any one or more of: the user equipment activates a TCI state of the LTM candidate cell; the user equipment is configured with one or more LTM events and when the conditions for an event are fulfilled for the LTM candidate cell or a beam of the LTM candidate cell, it triggers the user equipment to start acquiring CSI for the LTM candidate cell; and the user equipment is configured with at least two conditional LTM execution conditions and one of the conditional LTM execution conditions are satisfied.

[0034] In particular embodiments, the CSI configuration comprises an indication of what CSI quantities to be computed or reported.

[0035] According to some embodiments, a method is performed by a target network node. The method comprises: transmitting a CSI configuration for a user equipment to a source network node prior to an LTM cell switch of the user equipment; and receiving a CSI report from the user equipment based on the CSI configuration after an LTM cell switch of the user equipment.

[0036] In particular embodiments, the method further comprises transmitting an uplink grant to the user equipment. The uplink grant indicates transmission resources for the user equipment to use for transmitting the CSI report to the target network node.

[0037] According to some embodiments, a network node comprises processing circuitry operable to perform any of the network node methods described above.

[0038] Also disclosed is a computer program product comprising a non-transitory computer readable medium storing computer readable program code, the computer readable program code operable, when executed by processing circuitry to perform any of the methods performed by the user equipment described above.

[0039] Another computer program product comprises a non-transitory computer readable medium storing computer readable program code, the computer readable program code operable, when executed by processing circuitry to perform any of the methods performed by the network nodes described above.

[0040] Certain embodiments may provide one or more of the following technical advantages. For example, in particular embodiments, measurements on CSI-RS from a candidate cell may be used to speed up link adaptation in the candidate cell. The network is able to choose modulation and coding scheme for the physical downlink shared channel (PDSCH), and aggregation level for physical downlink control channel (PDCCH) from the first downlink (DL) transmissions in the candidate cell without having to wait for the regular channel quality indicator (CQI) reports.

[0041] The approach where the UE reports CSI after cell switch to the target cell has at least the following advantages compared to the other approach, where the CSI is reported to the serving cell before cell switch: (a) the UE can perform CSI measurements later because there is no need to reserve time to report the measurement to the candidate cell; (b) the CSI report is sent only once; (c) the CSI report is only sent for the target cell, not for multiple LTM candidates; and (d) the second approach is more generally applicable.BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The present disclosure may be best understood by way of example with reference to the following description and accompanying drawings that are used to illustrate embodiments of the present disclosure. In the drawings:Figure 1 is a flow diagram illustrating the procedure for layer one (Ll) / layer two (L2) triggered mobility (LTM);Figure 2A is a sequence diagram illustrating a procedure for channel state information (CSI) measurements on a candidate cell before LTM cell switch, where the measurements are forwarded via the serving cell to the candidate cell;Figure 2B is a sequence diagram illustrating a procedure for CSI measurements on a candidate cell before LTM cell switch, where the measurements are transmitted from the user equipment (UE) to the candidate cell;Figure 3 shows an example of a communication system, according to certain embodiments;Figure 4 shows a user equipment (UE), according to certain embodiments;Figure 5 shows a network node, according to certain embodiments;Figure 6 is a block diagram of a host, according to certain embodiments;Figure 7 is a flowchart illustrating an example method in a user equipment, according to certain embodiments;Figure 8 is a flowchart illustrating an example method in a source network node, according to certain embodiments; andFigure 9 is a flowchart illustrating an example method in a target network node, according to certain embodiments.DETAILED DESCRIPTION

[0043] As described above, certain challenges currently exist with layer one (Ll) / layer two (L2) triggered mobility (LTM) candidate cell channel state information (CSI) configuration and reporting. Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. For example, according to some embodiments, measurements on CSI reference signals (CSI-RS) from a candidate cell may be used to speed up link adaptation in the candidate cell.

[0044] Particular embodiments are 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.

[0045] The term “L1 / L2 based inter-cell mobility” may also be referred to as L1 / L2 mobility, Ll-mobility, LI based mobility, Ll / L2-centric inter-cell mobility, L1 / L2 inter-cell mobility, L1 / L2 triggered mobility, lower-layer triggered mobility or LTM. The basic principle is that a user equipment (UE) receives a lower layer signaling (e.g., a medium access control (MAC) control element (CE)) from the network indicating to the UE a change (or switch or activation) of included 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 (e.g., lower than Radio Resource Control (RRC)), which may be referred as a L1 / L2 inter-cell mobility execution command or LTM cell switch command. The change of serving cell (e.g., change of PCell) may also lead to a change in Scell(s) for the same cell group, e.g., if 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 cells (e.g., reception of an RRC Reconfiguration message, with at least one LTM candidate cell configuration) A candidate cell configuration may include parameters in the information element (IE) CellGroupConfig per candidate cell and / or an embedded RRC Reconfiguration per candidate cell.

[0046] The term LTM cell switch procedure refers to the process of a UE changing its cell from a source cell to a target cell (which may be referred to here as a candidate cell or a neighbor 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 dynamic switch, LTM switch, LTM cell switch, LTM serving cell change or LTM cell change. Even if the term change of cell is used, that may comprise a 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).

[0047] The LTM cell switch procedure may be triggered by the UE receiving an LTM cell switch command from the network. The source and target cells in an LTM cell switch procedure may be controlled by the same gNB, which sometimes is referred to as the intra-gNB case, or when the gNB uses a distributed CU / DU radio access network (RAN) architecture, the intra-CU inter- DU case or the intra-CU intra-DU case (depending on whether the cells are controlled by the same DU or different DUs). When the source and target cells in an LTM cell switch procedure are controlled by different gNBs, this is sometimes referred to as the inter-gNB case, or inter-CU case, or sometimes known as an inter-CU LTM cell switch procedure.

[0048] An LTM candidate cell configuration may also sometimes be referred to as a configuration of a LTM candidate cell, which may be an RRC configuration, such as encapsulatedin an RRC Reconfiguration message that the UE receives when being configured with L1 / L2 triggered mobility. An LTM candidate cell configuration comprises the configuration that a UE needs to start to operate accordingly when the UE performs an LTM cell switch procedure to the LTM candidate cell, e.g., upon reception of the LTM cell switch command indicating the UE to perform a LTM cell switch procedure to the LTM candidate cell, which becomes the target cell and the current (new) SpCell, or an sCell in a serving frequency. The LTM candidate cell configuration comprises parameters of a serving cell (or multiple serving cells, such as a cell group), comprising one or more of the groups of parameters, such as an RRCReconfiguration message, an IE CellGroupConfig or an IE SpCellConfig (or the IE sCellConfig, in the case of a Secondary Cell).

[0049] An LTM candidate cell configuration is associated with an identifier that 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 referred to as the LTM candidate cell configuration identity or LTM candidate configuration index (or similar).

[0050] An inter-CU LTM cell switch procedure, sometimes also referred to as inter-CU LTM or inter-gNB LTM, 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 when the execution LTM cell switch procedure was triggered (e.g., upon reception of the LTM cell switch command). From the 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(s).

[0051] Inter master node L1 / L2 triggered mobility, inter-MN LTM, configuration of inter- MN LTM, execution of inter-MN LTM and an inter-MN LTM cell switch procedure may be used interchangeably. As used herein, inter-MN LTM refers to inter-CU LTM, sometimes also referred to as inter-gNB LTM, handover or MCG mobility, when the UE is configured with dual connectivity, such as NR-DC, and where the source cell and target cell are both part of the source and target MCG, respectively, and controlled by different CUs or different gNBs.

[0052] The term conditional LTM refers to L1 / L2 triggered mobility where the execution of the LTM cell switch is triggered by the UE when an execution condition, such as a layer 1, layer 2 or a layer 3 event, criterion or condition related to, for example, a radio measurement, is fulfilled. Upon the cell switch the UE applies a stored LTM candidate cell configuration.

[0053] An inter-CU LTM candidate cell configuration is an LTM candidate cell configuration that contains the configuration that the UE needs to start to operate accordingly when the UE performs an LTM cell switch procedure to an LTM candidate cell that is controlled by a different base station, e.g. gNB, from the current source base station, e.g. serving gNB of the UE. In some cases, the UE may receive an inter-CU LTM candidate cell configuration during configuration of inter-MN LTM. In some cases, the UE may apply an inter-CU LTM candidate cell configuration during execution of inter-MN LTM.

[0054] 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 RRC IE RadioBearerConfig that includes SecurityConfig with Security AlgorithmConfig; indication to perform Packet Data Convergence Protocol (PDCP) re-establishment; and / or an indication to perform a full configuration, e.g. the RRC field fullConfig.

[0055] The terms mobility procedure, configuration of a mobility procedure or execution of a mobility procedure may be used interchangeably. As used herein, a mobility procedure may be L1 / L2 triggered mobility, LTM, inter-CU LTM, inter-MN LTM, L3 handover, PCell handover, conditional handover (CHO), conditional LTM, PSCell change or conditional PSCell Addition or Change (CP AC). Particular examples sometimes use the inter-MN LTM as an example. However, many of the examples may also be applied for other mobility procedures, for example, LTM, inter- CU LTM, conditional LTM or CHO.

[0056] Furthermore, particular embodiments are also applicable for Conditional LTM (CLTM), which may be viewed as a form of conditional reconfiguration. In CLTM, the UE is configured with an LTM candidate cell (denoted as a CLTM candidate cell), by receiving an LTM candidate cell configuration, as in legacy LTM, and referred to herein as a Conditional LTM candidate cell configuration, and an associated execution condition, denoted CLTM execution condition. The CLTM execution condition associated to a CLTM candidate cell is associated to the assessment of lower layer measurements, such as Layer 1 (LI) reference signal receive power (RSRP) and / or synchronization signal (SS)-RSRP, derived from SSBs and / or CSI-RSs of either the source cell and / or an CLTM candidate cell. Lower layer measurements, in this context, are measurements reported to support lower layer procedures like beam management, TCI state activations / deactivations, early timing advance (TA) acquisition, and link adaptation, and they are not filtered based on Layer 3 (L3) parameters, though there may be some filtering of these measurements based on lower layer parameters. The reception of CLTM execution condition mayalso involve receiving an indication of the condition and / or configuring it with parameters such as event identifier(s), offset(s), threshold(s), reference signal (RS) type, trigger quantity, time-to- trigger (TTT), and so forth.

[0057] When configured with CLTM, the UE evaluates the CLTM execution condition (referred to as Conditional LTM execution condition, LTM execution condition, or triggering condition) or a combination thereof. When the condition for a CLTM candidate cell is fulfilled, the UE performs a CLTM execution, which may be seen as a kind of LTM execution (but not triggered by the reception of an LTM cell switch command); this may also be considered as a kind of LTM cell switch, or Conditional LTM cell switch, or Conditional LTM execution. During the execution, the UE may apply a message, parts of a message, or at least one information element (IE), or perform a source cell switch or change. According to the methods outlined in particular embodiments, upon satisfaction of the execution condition(s), the UE initiates an LTM cell switch.

[0058] When a UE has been configured with a mobility configuration, the UE may use the mobility configuration during preparation of a mobility procedure, including measurements (such as RSRP measurements on neighbor or serving cells), triggering and transmission of measurement reports, synchronization towards neighbor cells, evaluation of conditions (for conditional mobility, e.g., CHO), and during the execution of a mobility procedure (e.g., execution of an LTM cell switch procedure, execution of an inter-MN LTM cell switch procedure or execution of handover).

[0059] A mobility configuration may include one or multiple of the following type of elements where each element contains a configuration of one aspect of LTM, for example as follows:• LTM candidate cell configuration(s),• inter-CU LTM candidate cell configuration(s),• lower layer information, such as physical layer configuration, MAC layer configuration or Radio Link Control (RLC) layer configuration, cell group configuration, serving cell configuration.• higher layer information, such as RRC protocol parameters, such as timer values, PDCP layer configuration, radio bearer configuration or measurement configuration• Configuration of measurements for LTM• Configuration for measurement reports for LTM• CSI resource configuration(s) for LTM• CSI report configuration for LTM• Configurations of early synchronization procedures, such as• Configurations for DL pre-synchronization for LTM, such as configurations for early TCI state activation• Configurations for UL pre- synchronization for LTM, such as configurations for reception of PDCCH ordered triggered preamble transmission and reception of TA.• Configurations for the execution of an LTM cell switch procedure for a given LTM candidate cell configuration or inter-CU LTM candidate cell configuration (e.g., whether to perform random access procedure, whether to perform RLC reestablishment, or MAC reset, or PDCP recovery), a timer value, configured UL grants, dedicated RA preambles.• A configuration that the UE needs to start to operate accordingly when it performs an LTM cell switch procedure to an LTM candidate cell that is controlled by a different base station, e.g. gNB, from the current source base station, e.g. serving gNB, of the UE.• Information to perform security key refresh, e.g., the RRC IE MasterKeyUpdate or a RRC IE RadioBearerConfig that includes SecurityConfig with Security AlgorithmConfig.• Indication to perform a full configuration, e.g., the RRC field fullConfig.• Indication to perform L2 re-establishment, such as an indication to perform PDCP reestablishment for one or multiple bearers.

[0060] The term “subsequent LTM”, sometimes also referred to a “subsequent LTM cell switch (procedures)” refers to that the UE performs a first LTM cell switch procedure from a source cell to a first target cell, then performs a second LTM cell switch procedure from the first target cell (which is now the new source cell) to a second target cell, and between the first and second LTM cell switch procedures there is no RRC reconfiguration of the UE. This implies also that the network does not add / remove / modify the LTM candidate cell configuration(s) or inter-CU LTM candidate cell configuration(s) in the UE between the two LTM cell switch procedures.

[0061] The term “cell” is used herein to identify a location (or coverage) on which the UE is located. However, the term “cell” may also be exchanged without any loss of meaning with the terms “radio resources”, “beams”, “TCI state”, or “TRS”. This is to clarify that particular embodiments do not target specifically a scenario where there is a cell, but rather when a UE uses a set of source radio resources and need to switch to a target set of radio resources. In such a case, radio resource can also identify a set of configurations, field, parameters, or ASN.1 structures or IES.

[0062] The term “early DL synchronization” is used herein to describe the action performed by the UE of pre-activating a TCI state of at least one LTM candidate cell configuration before performing an LTM cell switch execution. In this case, the TCI state on a given LTM candidate cell is “activated in advance,” or “pre-activated.” Therefore, the terms “early DL synchronization,”or “early TCI state activation,” or “early TCI state pre-activation” may be exchanged without any loss of meaning. Moreover, the terms “first network node” and “second network node” refer to a source cell / serving cell / source gNB-DU / S-DU and a candidate cell / candidate gNB-DU / C-DU respectively.

[0063] Some embodiments include UE methods. For example, a method in a user equipment (UE) that is configured with at least one LTM candidate configuration that includes CSI resources that are transmitted by the candidate cell comprises: obtaining information about which LTM candidates that the UE should acquire CSI for, including what CSI quantities that should be computed and possibly reported; measuring CSI for LTM candidates; receiving an LTM Cell switch command to one of the LTM candidate cells; and reporting the CSI to the new serving cell (e.g., the LTM candidate cell indicated in the LTM cell switch command or the LTM candidate cell for which Conditional LTM execution conditions are satisfied).

[0064] Some embodiments indicate which LTM candidate cells should be measured and what CSI parameters.

[0065] In some embodiments, the UE obtains information about which LTM candidates that the UE should acquire CSI for and what CSI quantities that should be acquired and reported, by any of the following.

[0066] For example, the UE may receive from the serving cell a CSI configuration that explicitly identifies the LTM candidates and resources that the UE should measure CSI on. In one alternative, the CSI configuration takes immediate effect, i.e. the UE applies the CSI configuration and directly starts CSI acquisition accordingly. In another alternative, the CSI configuration is associated with conditions. When the conditions are met for an LTM candidate, then the UE starts CSI acquisition according to the CSI configuration.

[0067] The CSI configuration may be included in the RRC LTM-CSI-ReportConfig and / or LTM-CSI-ResourceConfig IES with potentially new extensions.

[0068] The CSI configuration may include a CSI Resource configuration, or an LTM CSI Resource configuration. The CSI Resource configuration or the LTM CSI resource configuration may include one or more CSI-RS resources, where each CSI-RS resource may have multiple ports. The CSI Resource configuration or the LTM CSI resource configuration may also include one or more CSI-RS resource sets. In some cases, the CSI Resource configuration is a CSI- ResourceConfig RRC IE, and the LTM CSI Resource configuration is an LTM-CSI- ResourceConfig RRC IE.

[0069] The CSI configuration may further include an indication to indicate to the UE that the acquired CSI quantities should be reported to the new serving cell after an LTM cell switch isexecuted. This indication may be specific to CSI configuration received from an LTM candidate or it may be more general, meaning that one indication indicates that acquired CSI quantities should be reported to the new serving cell after an LTM cell switch procedure is executed, no matter which cell is the new serving cell.

[0070] In some embodiments, the conditions to measure CSI on an LTM candidate cell configured with CSI-RS is that: the UE is activating or has activated a TCI State of the LTM candidate cell; the UE is configured with one or more LTM events, e.g. LTM2 / LTM3 / LTM4 etc., and when the conditions for one event are fulfilled for a cell or a beam of a cell, it triggers the UE to start acquiring CSI for that cell; and / or the UE is configured with at least two Conditional LTM execution conditions, referred to as Cl and C2, and one of the CLTM execution conditions, i.e. Cl or C2, are satisfied.

[0071] Some embodiments indicate what CSI should be acquired. In some embodiments, the CSI parameters that should be acquired by the UE can be one or more of CSI-RS resource indicator (CRI), channel quality indicator (CQI), precoding matrix indicator (PMI) and rank indicator (RI) for a Type I or a Type II codebook. Furthermore, the CSI configuration received by the UE may include additional information regarding, e.g., the frequency granularity of the CSI that the UE should acquire and later report.

[0072] In some embodiments, the information about what CSI that should be measured / collected may be received from the serving cell as part of LTM CSI Configuration.

[0073] Some embodiments perform measurements and store results In some embodiments, the UE acquires the CSI parameters on the CSI resources configured for the LTM candidates.

[0074] In some embodiments, the CSI is acquired periodically / semi-statically or dynamically, depending on the CSI resource and report configuration.

[0075] Some embodiments report CSI after cell switch. In some embodiments, the UE has received LTM Cell Switch command targeting an LTM candidate cell for which the UE has acquired CSI, or the Conditional LTM execution conditions are satisfied for an LTM candidate cell for which the UE has acquired the CSI, and where the UE sends a CSI report to the new serving cell.

[0076] In some embodiments, the CSI is sent in a MAC CE to the new serving cell.

[0077] In some embodiments, the UE indicates to the new source cell that it can send a CSI report. This can be indicated in the RRCReconfigurationComplete message that completes the cell switch.

[0078] In some embodiments, the UE receives a DCI from the new source cell that triggers the UE to send the CSI Report.

[0079] In some embodiments, the CSI report is sent as part of the RRCReconfigurationComplete message that completes the cell switch.

[0080] In some embodiments, the LTM Cell Switch includes an uplink grant for the UE in the new source cell, and the UE transmits the CSI report with the uplink grant.

[0081] In some embodiments, the UE sends the report after sending the RRCReconfigurationComplete message and after receiving an indication from the network that requests the UE to send the report. The request from the network may be a new or existing RRC message, or a (new or existing) MAC CE.

[0082] In some embodiments, the UE sends the CSI report to the new serving cell based on an indication which was included within the CSI related configuration received by a LTM candidate cell.

[0083] In some embodiments, the UE asks for a UL grant which is big enough to include the RRCReconfigurationComplete message and the CSI report, if the CSI report is sent in a separate RRC message or within a MAC CE.

[0084] In some embodiments, the UE sends first the CSI report to the new serving cell and then the RRCReconfigurationComplete message.

[0085] Some embodiments are from the perspective of the source cell. For example, a method at a first network node (the LTM source cell), which has provided to the UE at least one LTM candidate cell configuration including CSI resources that are transmitted by the candidate cell, comprises: requesting information from one or more network nodes, e.g., the LTM target cells, about the CSI configuration for each network node; receiving information from one or more network nodes, e.g., the LTM target cells, about the CSI configuration for each network node; providing the UE with CSI configuration(s) for at least some of the one or more network nodes including what CSI quantities that should be computed and possibly reported; receiving a CSI report from the UE; and informing a second network node, e.g. the LTM target cell, about the received CSI report received for the second network node.

[0086] In some embodiments, the LTM source cell provides the UE with information about which LTM candidates that it should acquire CSI for and what CSI quantities that should be acquired and reported, by sending from the serving cell a CSI configuration that explicitly identifies the LTM candidates and resources that the UE should measure CSI on. The CSI configuration may be included in the RRC LTM-CSI-ReportConfig and / or LTM-CSI- ResourceConfig IES with extensions.

[0087] The CSI configuration may further comprise an indication on whether the UE should report the CSI report to the new serving cell after an LTM cell switch procedure is triggered. Inone example, the indication is included only if the UE has previously reported the support for sending the CSI report to the new serving cell after an LTM cell switch procedure is triggered.

[0088] The CSI configuration may be associated with conditions: When the conditions are met, the CSI configuration should be applied. In one example, the condition for applying the CSI configuration is that a TCI state of an LTM candidate cell is being or has been activated.

[0089] In some embodiments, the LTM source cell provides the LTM target cell or some other cell about a CSI configuration, the method comprising informing the LTM target cell about a CSI configuration of the UE. The CSI configuration consists of a CSI resource configuration and CSI report configuration. The CSI resource configuration typically includes CSI resources of the LTM target cell but may also include other CSI resources. In one option, the CSI configuration is provided with the LTM Cell Switch Notification sent from the DU of the serving cell to the DU of the target cell (or some other cell).

[0090] In some embodiments, the CSI report is sent to the second network node after triggering a LTM cell switch procedure at the UE toward the second network node.

[0091] In one example, the CSI report is sent in the same message that is used to inform the second network that an LTM cell switch procedure has been triggered to the second network node.

[0092] In one example, the CSI report is sent in a separate message which may be sent before or after the indication that an LTM cell switch procedure has been triggered to the second network node.

[0093] In some embodiments, the CSI report is sent by the first network node to the second network node after receiving an indication of the completion of LTM cell switch procedure by the UE, as determined by the Conditional LTM execution conditions. In one example, the CSI report is sent by the first network node to the second network node in an existing or a new class 1 or class 2 message which may be sent before receiving the indication that an LTM cell switch procedure to the second network node has been completed.

[0094] In another example, the CSI report is sent by the first network node via a class 1 Message, e g., UE CONTEXT MODIFICATION REQUEST or UE CONTEXT MODIFCATION RESPONSE Message, either directly or via gNB-CU to the second network node, after receiving the indication that an LTM cell switch procedure to the second network node has been completed.

[0095] In yet another example, the CSI report is sent by the first network node via an existing or new class 2 Message, either directly or via gNB-CU to the second network node, after receiving the indication that an LTM cell switch procedure to the second network node has been completed.

[0096] Some embodiments are from the perspective of the target cell. For example, a method at a second network node that is the target of LTM execution for a UE comprises sending a CSIconfiguration to a first network node, e.g., the source cell, or receiving a CSI configuration for the UE from the previous source cell and receiving a CSI report from the UE.

[0097] In some embodiments, the LTM target cell receives from the LTM source cell a CSI configuration. The CSI configuration consists of a CSI resource configuration and CSI report configuration. The CSI resource configuration typically includes CSI resources of the LTM target cell but may also include other CSI resources. In one option, the CSI configuration is received with the LTM Cell Switch Notification from the DU of the serving cell.

[0098] In some embodiments, the CSI report is received over MAC CE.

[0099] In some embodiments, the second network node triggers the CSI report. In some embodiments, the triggering includes an UL grant.

[0100] In some embodiments, the CSI configuration may further comprise an indication on whether the UE should report the CSI report to the new serving cell after an LTM cell switch procedure is triggered.

[0101] In one example, the indication is included only if the UE has previously reported the support for sending the CSI report to the new serving cell after an LTM cell switch procedure is triggered.

[0102] In some embodiments, the CSI report is received by the first network node after triggering a LTM cell switch procedure at the UE.

[0103] In one example, the CSI report is received in the same message that is used by the first network node to inform the second network that an LTM cell switch procedure has been triggered to the second network node.

[0104] In one example, the CSI report is received in a separate message which may be received before or after the indication that an LTM cell switch procedure has been triggered by the first network node.

[0105] In some embodiments, the CSI report is received by the second network node after the first network node receives an indication of the completion of LTM cell switch procedure by the UE, as determined by the Conditional LTM execution conditions.

[0106] In one example, the CSI report is received by the second network node in an existing or new class 1 or class 2 message which may be sent before the first network node receives the indication that an LTM cell switch procedure to the second network node has been completed.

[0107] In another example, the CSI report is received by the second network node via a class 1 Message, e.g, UE CONTEXT MODIFICATION REQUEST or UE CONTEXT MODIFCATION RESPONSE Message, either directly or via gNB-CU from the first networknode, after the first network node receives the indication that an LTM cell switch procedure to the second network node has been completed.

[0108] In yet another example, the CSI report is received by the second network node via an existing or new class 2 Message, either directly or via gNB-CU from the first network node, after the first network node receives the indication that an LTM cell switch procedure to the second network node has been completed.

[0109] There may be multiple potential impacts to the specifications, including the following. With respect to TS 38.331 and the RRC protocol:• Extension to LTM-CSI-ReportConfig or CSI-ReportConfig that indicates to the UE that the CSI Report should be sent to the target cell after cell switch command, or to the serving cell before cell switch command.• Extension to LTM-CSI-ReportConfig or CSI-ReportConfig that indicates a condition that should be met for the UE to acquire the CSI.• Extension to LTM-CSI-ReportConfig for the CSI quantities or parameters that should be reported (e.g., CQI, PMI and RI, etc.).• Extension to RRCReconfigurationComplete to include the CSI report from the UE.

[0110] Some embodiments may include changes to TS 38.473 and the Fl Application Protocol.

[0111] Figure 3 shows an example of a communication system 100 in accordance with some embodiments. In the example, the communication system 100 includes a telecommunication network 102 that includes an access network 104, such as a radio access network (RAN), and a core network 106, which includes one or more core network nodes 108. The access network 104 includes one or more access network nodes, such as network nodes 110a and 110b (one or more of which may be generally referred to as network nodes 110), or any other similar 3rd Generation Partnership Project (3GPP) access node or non-3GPP access point. The network nodes 110 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 112a, 112b, 112c, and 112d (one or more of which may be generally referred to as UEs 112) to the core network 106 over one or more wireless connections.

[0112] 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 100 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 / orsignals whether via wired or wireless connections. The communication system 100 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0113] The UEs 112 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 110 and other communication devices. Similarly, the network nodes 110 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 112 and / or with other network nodes or equipment in the telecommunication network 102 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 102.

[0114] In the depicted example, the core network 106 connects the network nodes 110 to one or more hosts, such as host 116. 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 106 includes one more core network nodes (e.g., core network node 108) 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 108. 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).

[0115] The host 116 may be under the ownership or control of a service provider other than an operator or provider of the access network 104 and / or the telecommunication network 102 and may be operated by the service provider or on behalf of the service provider. The host 116 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as 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.

[0116] As a whole, the communication system 100 of Figure 3 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, butare not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

[0117] In some examples, the telecommunication network 102 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunications network 102 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 102. For example, the telecommunications network 102 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.

[0118] In some examples, the UEs 112 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 104 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 104. 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).

[0119] In the example, the hub 114 communicates with the access network 104 to facilitate indirect communication between one or more UEs (e.g., UE 112c and / or 112d) and network nodes (e.g., network node 110b). In some examples, the hub 114 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 114 may be a broadband router enabling access to the core network 106 for the UEs. As another example, the hub 114 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 110, or by executable code, script, process, or other instructions in the hub 114. As another example, the hub 114 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 114 may be a content source. For example, for a UE that is a VR headset, display,loudspeaker or other media delivery device, the hub 114 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 114 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 114 acts as a proxy server or orchestrator for the UEs, in particular in if one or more of the UEs are low energy loT devices.

[0120] The hub 114 may have a constant / persistent or intermittent connection to the network node 110b. The hub 114 may also allow for a different communication scheme and / or schedule between the hub 114 and UEs (e.g., UE 112c and / or 112d), and between the hub 114 and the core network 106. In other examples, the hub 114 is connected to the core network 106 and / or one or more UEs via a wired connection. Moreover, the hub 114 may be configured to connect to an M2M service provider over the access network 104 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 110 while still connected via the hub 114 via a wired or wireless connection. In some embodiments, the hub 114 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 110b. In other embodiments, the hub 114 may be a nondedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 110b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0121] Figure 4 shows a UE 200 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 cameras, 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-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3rd Generation Partnership Project (3GPP), including a narrow band internet of things (NB-IoT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0122] A UE may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to- everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that isintended 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).

[0123] The UE 200 includes processing circuitry 202 that is operatively coupled via a bus 204 to an input / output interface 206, a power source 208, a memory 210, a communication interface 212, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 2. 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.

[0124] The processing circuitry 202 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 210. The processing circuitry 202 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 202 may include multiple central processing units (CPUs).

[0125] In the example, the input / output interface 206 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 200. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0126] In some embodiments, the power source 208 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 208 may further include power circuitry for delivering power from the power source 208 itself, and / or an external power source, to the various parts of the UE 200 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 208. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 208 to make the power suitable for the respective components of the UE 200 to which power is supplied.

[0127] The memory 210 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 210 includes one or more application programs 214, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 216. The memory 210 may store, for use by the UE 200, any of a variety of various operating systems or combinations of operating systems.

[0128] The memory 210 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 ‘SIM card.’ The memory 210 may allow the UE 200 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 210, which may be or comprise a device-readable storage medium.

[0129] The processing circuitry 202 may be configured to communicate with an access network or other network using the communication interface 212. The communication interface 212 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 222. The communication interface 212 may include one or more transceivers used to communicate, such as by communicating with one or more remotetransceivers 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 218 and / or a receiver 220 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 218 and receiver 220 may be coupled to one or more antennas (e.g., antenna 222) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0130] In the illustrated embodiment, communication functions of the communication interface 212 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.

[0131] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 212, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0132] 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 to a robotic arm performing a medical procedure according to the received input.

[0133] 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 a device which is or which is embedded in: a connected refrigerator or freezer, a TV, aconnected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, amotion detector, a thermostat, asmoke detector, adoor / 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 itemtracking 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 of the intended application of the loT device in addition to other components as described in relation to the UE 200 shown in Figure 2.

[0134] As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements and transmits the results of such monitoring and / or measurements to another UE and / or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-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.

[0135] 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.

[0136] Figure 5 shows a network node 300 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)).

[0137] 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 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).

[0138] 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).

[0139] The network node 300 includes a processing circuitry 302, a memory 304, a communication interface 306, and a power source 308. The network node 300 may be composed of multiple physically separate components (e.g., aNodeB 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 300 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 300 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 304 for different RATs) and some components may be reused (e.g., a same antenna 310 may be shared by different RATs). The network node 300 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 300, 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 300.

[0140] The processing circuitry 302 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 300 components, such as the memory 304, to provide network node 300 functionality.

[0141] In some embodiments, the processing circuitry 302 includes a system on a chip (SOC). In some embodiments, the processing circuitry 302 includes one or more of radio frequency (RF) transceiver circuitry 312 and baseband processing circuitry 314. In some embodiments, the radio frequency (RF) transceiver circuitry 312 and the baseband processing circuitry 314 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 312 and baseband processing circuitry 314 may be on the same chip or set of chips, boards, or units.

[0142] The memory 304 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 302. The memory 304 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 302 and utilized by the network node 300. The memory 304 may be used to store any calculations made by the processing circuitry 302 and / or any data received via the communication interface 306. In some embodiments, the processing circuitry 302 and memory 304 is integrated.

[0143] The communication interface 306 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 306 comprises port(s) / terminal(s) 316 to send and receive data, for example to and from a network over a wired connection. The communication interface 306 also includes radio front-end circuitry 318 that may be coupled to, or in certain embodiments a part of, the antenna 310. Radio front-end circuitry 318 comprises filters 320 and amplifiers 322. The radio front-end circuitry 318 may be connected to an antenna 310 and processing circuitry 302. The radio front-end circuitry may be configured to condition signals communicated between antenna310 and processing circuitry 302. The radio front-end circuitry 318 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 318 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 320 and / or amplifiers 322. The radio signal may then be transmitted via the antenna 310. Similarly, when receiving data, the antenna 310 may collect radio signals which are then converted into digital data by the radio front-end circuitry 318. The digital data may be passed to the processing circuitry 302. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0144] In certain alternative embodiments, the network node 300 does not include separate radio front-end circuitry 318, instead, the processing circuitry 302 includes radio front-end circuitry and is connected to the antenna 310. Similarly, in some embodiments, all or some of the RF transceiver circuitry 312 is part of the communication interface 306. In still other embodiments, the communication interface 306 includes one or more ports or terminals 316, the radio front-end circuitry 318, and the RF transceiver circuitry 312, as part of a radio unit (not shown), and the communication interface 306 communicates with the baseband processing circuitry 314, which is part of a digital unit (not shown).

[0145] The antenna 310 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 310 may be coupled to the radio front-end circuitry 318 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 310 is separate from the network node 300 and connectable to the network node 300 through an interface or port.

[0146] The antenna 310, communication interface 306, and / or the processing circuitry 302 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 310, the communication interface 306, and / or the processing circuitry 302 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.

[0147] The power source 308 provides power to the various components of network node 300 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 308 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 300 with power forperforming the functionality described herein. For example, the network node 300 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 308. As a further example, the power source 308 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.

[0148] Embodiments of the network node 300 may include additional components beyond those shown in Figure 5 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 300 may include user interface equipment to allow input of information into the network node 300 and to allow output of information from the network node 300. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 300.

[0149] Figure 6 is a block diagram of a host 400, which may be an embodiment of the host 116 of Figure 1, in accordance with various aspects described herein. As used herein, the host 400 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 400 may provide one or more services to one or more UEs.

[0150] The host 400 includes processing circuitry 402 that is operatively coupled via a bus 404 to an input / output interface 406, a network interface 408, a power source 410, and a memory 412. Other components may be included in other embodiments. Features of these components may be substantially similar to those described with respect to the devices of previous figures, such as Figures 10 and 3, such that the descriptions thereof are generally applicable to the corresponding components of host 400.

[0151] The memory 412 may include one or more computer programs including one or more host application programs 414 and data 416, which may include user data, e.g., data generated by a UE for the host 400 or data generated by the host 400 for a UE. Embodiments of the host 400 may utilize only a subset or all of the components shown. The host application programs 414 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 414 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 400 may select and / or indicate a different host for over-the-top services for a UE. The host application programs 414 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.

[0152] Figure 7 is a flowchart illustrating an example method 700 in a user equipment, according to certain embodiments. In particular embodiments, one or more steps of Figure 7 may be performed by UE 200 described with respect to Figure 4. The user equipment is operable to perform LTM.

[0153] The method begins at step 712, where the user equipment (e.g., UE 200) obtains an indication of one or more LTM candidate cells for which the user equipment is to acquire CSI. The user equipment may obtain the indication from a source / serving network node.

[0154] In particular embodiments, obtaining the indication of the one or more LTM candidate cells for which the user equipment is to acquire CSI comprises receiving from a serving cell a CSI configuration.

[0155] In particular embodiments, the CSI configuration comprises an indication that the CSI configuration takes effect upon receipt of the CSI configuration or upon fulfillment of a condition associated with an LTM candidate cell.

[0156] In particular embodiments, the condition comprises any one or more of: the user equipment activates a transmission configuration indicator (TCI) state of the LTM candidate cell; the user equipment is configured with one or more LTM events and when the conditions for an event are fulfilled for the LTM candidate cell or a beam of the LTM candidate cell, it triggers the user equipment to start acquiring CSI for the LTM candidate cell; and the user equipment is configured with at least two conditional LTM execution conditions and one of the conditional LTM execution conditions are satisfied.

[0157] In particular embodiments, the CSI configuration comprises an indication of what CSI quantities to be computed or reported.

[0158] In particular embodiments, the CSI configuration comprises any of the configurations described with respect to the embodiments and examples described herein.

[0159] At step 714, the user equipment measures CSI for the one or more LTM candidate cells. For example, the user equipment may measure CSI according to the received CSIconfiguration. In particular embodiments, the user equipment measures CSI according to any of the embodiments and examples described herein.

[0160] At step 716, the user equipment determines to perform an LTM cell switch to a target LTM candidate cell of the one or more LTM candidate cells. For example, the user equipment may receive an LTM command from a network node, or the user equipment may determine an LTM condition is satisfied. In particular embodiments, the user equipment determines to perform the LTM cell switch according to any of the embodiments and examples described herein.

[0161] At step 718, the user equipment reports the CSI measurements of the target LTM candidate cell to the target candidate cell. In particular embodiments, reporting the CSI measurements of the target LTM candidate cell to the target candidate cell comprises reporting the CSI measurements in a Radio Resource Control Reconfiguration Complete message. In particular embodiments, reporting the CSI measurements of the target LTM candidate cell to the target candidate cell comprises reporting the CSI measurements in an uplink grant provided as part of an LTM cell switch command. In particular embodiments, the user equipment reports the CSI measurements according to any of the embodiments and examples described herein.

[0162] Modifications, additions, or omissions may be made to method 700 of Figure 7. Additionally, one or more steps in the method of Figure 7 may be performed in parallel or in any suitable order.

[0163] Figure 8 is a flowchart illustrating an example method 800 in a source network node, according to certain embodiments. In particular embodiments, one or more steps of Figure 8 may be performed by network node 300 described with respect to Figure 5.

[0164] The method begins at step 812, where the network node (e.g., network node 300) obtaining a CSI configuration from one or more LTM candidate cells.

[0165] In particular embodiments, the CSI configuration comprises an indication that the CSI configuration takes effect upon receipt of the CSI configuration or upon fulfillment of a condition associated with the LTM candidate cell.

[0166] In particular embodiments, the condition comprises any one or more of: the user equipment activates a TCI state of the LTM candidate cell; the user equipment is configured with one or more LTM events and when the conditions for an event are fulfilled for the LTM candidate cell or a beam of the LTM candidate cell, it triggers the user equipment to start acquiring CSI for the LTM candidate cell; and the user equipment is configured with at least two conditional LTM execution conditions and one of the conditional LTM execution conditions are satisfied.

[0167] In particular embodiments, the CSI configuration comprises an indication of what CSI quantities to be computed or reported.

[0168] In particular embodiments, the CSI configuration comprises any of the configurations described with respect to the embodiments and examples described herein.

[0169] At step 814, the network node transmits the CSI configuration to a user equipment. The user equipment may use the CSI configuration to perform CSI measurements in advance of an LTM switch so that the CSI measurements are readily available to the target network node after the LTM switch.

[0170] At step 816, the network node transmits an LTM cell switch command for one of the one or more LTM candidate cells to the user equipment.

[0171] Modifications, additions, or omissions may be made to method 800 of Figure 8. Additionally, one or more steps in the method of Figure 8 may be performed in parallel or in any suitable order.

[0172] Figure 9 is a flowchart illustrating an example method 900 in a target network node, according to certain embodiments. In particular embodiments, one or more steps of Figure 9 may be performed by network node 300 described with respect to Figure 5.

[0173] The method begins at step 912, where the target network node (e.g., network node 300) transmits a CSI configuration for a user equipment to a source network node prior to an LTM cell switch of the user equipment. The CSI configuration is described in more detail with respect to FIGURES 7 and 8 and with respect to the embodiments and examples described herein.

[0174] At step 914, the network node may transmit an uplink grant to the user equipment. The uplink grant indicates transmission resources for the user equipment to use for transmitting the CSI report to the target network node.

[0175] At step 916, the network node receives a CSI report from the user equipment based on the CSI configuration after an LTM cell switch of the user equipment. In some embodiments, the network node receives the CSI report in the uplink grant from optional step 914. In some embodiments, the network node receives the CSI report in another message, such as an RRC message. In particular embodiments, the network node receives the CSI report according to any of the embodiments and examples described herein.

[0176] Modifications, additions, or omissions may be made to method 900 of Figure 9. Additionally, one or more steps in the method of Figure 9 may be performed in parallel or in any suitable order.

[0177] The foregoing description sets forth numerous specific details. It is understood, however, that embodiments may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not toobscure the understanding of this description. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation.

[0178] References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to implement such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described.

[0179] Although this disclosure has been described in terms of certain embodiments, alterations and permutations of the embodiments will be apparent to those skilled in the art. Accordingly, the above description of the embodiments does not constrain this disclosure. Other changes, substitutions, and alterations are possible without departing from the scope of this disclosure, as defined by the claims below.

[0180] Some example embodiments are described below.Group A Embodiments1. A method performed by a user equipment, the method comprising:- obtaining an indication of one or more LTM candidate cells for which the user equipment should acquire CSI;- measuring CSI for the one or more LTM candidate cells;- determining to perform an LTM cell switch to a target LTM candidate cell of the one or more LTM candidate cells;- and reporting CSI measurements of the target LTM candidate cell to the target candidate cell.2. The method of the previous embodiment, wherein obtaining the indication of one or more LTM candidate cells for which the user equipment should acquire CSI comprises receiving from a serving cell a CSI configuration.3. The method of the previous embodiment, wherein the CSI configuration comprises an indication that the configuration takes effect upon receipt of the CSI configuration.4. The method of embodiment 2, wherein the CSI configuration comprises an indication thatthe configuration takes effect upon fulfillment of a condition associated with an LTM candidate cell.5. The method of the previous embodiment, wherein the condition comprises any one or more of: the user equipment activates a TCI State of a LTM candidate cell; the UE is configured with one or more LTM events and when the conditions for an event are fulfilled for a cell or a beam of a cell, it triggers the user equipment to start acquiring CSI for that cell. the UE is configured with at least two Conditional LTM execution conditions and one of the CLTM execution conditions are satisfied.6. The method of any one of the previous embodiments, wherein reporting CSI measurements of the target LTM candidate cell to the target candidate cell comprising reporting the CSI measurements in an RRC Reconfiguration Complete message.7. The method of any one of the previous embodiments, wherein reporting CSI measurements of the target LTM candidate cell to the target candidate cell comprising reporting the CSI measurements in an uplink grant provided as part of a LTM cell switch command.8. A method performed by a user equipment, the method comprising:- any of the user equipment steps, features, or functions described above, either alone or in combination with other steps, features, or functions described above.9. The method of the previous embodiment, further comprising one or more additional user equipment steps, features or functions described above.Group B Embodiments10. A method performed by a first network node, the method comprising:- obtaining a CSI configuration from one or more LTM candidate cells;- transmitting the CSI configuration to a user equipment;- receiving a CSI report from the user equipment for a target LTM candidate cell of the one ore more LTM candidate cells; andtransmitting the CSI report to the target LTM candidate cell.11. The method of the previous embodiment, wherein the CSI configuration comprises an indication that the configuration takes effect upon receipt of the CSI configuration.12. The method of embodiment 10, wherein the CSI configuration comprises an indication that the configuration takes effect upon fulfillment of a condition associated with an LTM candidate cell.13. The method of the previous embodiment, wherein the condition comprises any one or more of: the user equipment activates a TCI State of a LTM candidate cell; the user equipment is configured with one or more LTM events and when the conditions for an event are fulfilled for a cell or a beam of a cell, it triggers the user equipment to start acquiring CSI for that cell. the UE is configured with at least two Conditional LTM execution conditions and one of the CLTM execution conditions are satisfied.14. A method performed by a second network, the method comprising:- transmitting a CSI configuration to a first network node; and- receiving a CSI report from the first network node based upon LTM execution.15. A method performed by a network node, the method comprising:- any of the steps, features, or functions described above with respect to a network node, either alone or in combination with other steps, features, or functions described above.16. The method of the previous embodiment, further comprising one or more additional network node steps, features or functions described above.Group C Embodiments17. A user equipment, comprising: processing circuitry configured to perform any of the steps of any of the Group A embodiments; andpower supply circuitry configured to supply power to the processing circuitry.18. A network node, the network node comprising: processing circuitry configured to perform any of the steps of any of the Group B embodiments; power supply circuitry configured to supply power to the processing circuitry.19. 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.

Claims

Claims1. A method (700) performed by a user equipment (200), the method comprising: obtaining (712) an indication of one or more layer one / layer two triggered mobility, LTM, candidate cells for which the user equipment is to acquire channel state information, CSI; measuring (714) CSI for the one or more LTM candidate cells; determining (716) to perform an LTM cell switch to a target LTM candidate cell of the one or more LTM candidate cells; and reporting (718) the CSI measurements of the target LTM candidate cell to the target candidate cell.

2. The method of claim 1, wherein obtaining the indication of the one or more LTM candidate cells for which the user equipment is to acquire CSI comprises receiving from a serving cell a CSI configuration.

3. The method of claim 2, wherein the CSI configuration comprises an indication that the CSI configuration takes effect upon receipt of the CSI configuration.

4. The method of claim 2, wherein the CSI configuration comprises an indication that the CSI configuration takes effect upon fulfillment of a condition associated with an LTM candidate cell.

5. The method of claim 4, wherein the condition comprises any one or more of: the user equipment activates a transmission configuration indicator, TCI, state of the LTM candidate cell; the user equipment is configured with one or more LTM events and when the conditions for an event are fulfilled for the LTM candidate cell or a beam of the LTM candidate cell, it triggers the user equipment to start acquiring CSI for the LTM candidate cell; and the user equipment is configured with at least two conditional LTM execution conditions and one of the conditional LTM execution conditions are satisfied.

6. The method of claim 2, wherein the CSI configuration comprises an indication of what CSI quantities to be computed or reported.

7. The method of any one of claims 1-6, wherein reporting the CSI measurements of the target LTM candidate cell to the target candidate cell comprises reporting the CSI measurements in a Radio Resource Control Reconfiguration Complete message.

8. The method of any one of claims 1-6, wherein reporting the CSI measurements of the target LTM candidate cell to the target candidate cell comprises reporting the CSI measurements in an uplink grant provided as part of an LTM cell switch command.

9. A user equipment (200) comprising processing circuitry (202) operable to: obtain an indication of one or more layer one / layer two triggered mobility, LTM, candidate cells for which the user equipment is to acquire channel state information, CSI; measure CSI for the one or more LTM candidate cells; determine to perform an LTM cell switch to a target LTM candidate cell of the one or more LTM candidate cells; and report the CSI measurements of the target LTM candidate cell to the target candidate cell.

10. The user equipment of claim 9, wherein the processing circuitry is operable to obtain the indication of the one or more LTM candidate cells for which the user equipment is to acquire CSI by receiving from a serving cell a CSI configuration.

11. The user equipment of claim 10, wherein the CSI configuration comprises an indication that the CSI configuration takes effect upon receipt of the CSI configuration.

12. The user equipment of claim 10, wherein the CSI configuration comprises an indication that the CSI configuration takes effect upon fulfillment of a condition associated with an LTM candidate cell.

13. The user equipment of claim 12, wherein the condition comprises any one or more of: the user equipment activates a transmission configuration indicator, TCI, state of the LTM candidate cell; the user equipment is configured with one or more LTM events and when the conditions for an event are fulfilled for the LTM candidate cell or a beam of the LTM candidate cell, it triggers the user equipment to start acquiring CSI for the LTM candidate cell; and the user equipment is configured with at least two conditional LTM execution conditionsand one of the conditional LTM execution conditions are satisfied.

14. The user equipment of claim 10, wherein the CSI configuration comprises an indication of what CSI quantities to be computed or reported.

15. The user equipment of any one of claims 9-14, wherein the processing circuitry is operable to report the CSI measurements of the target LTM candidate cell to the target candidate cell by reporting the CSI measurements in a Radio Resource Control Reconfiguration Complete message.

16. The user equipment of any one of claims 9-14, wherein the processing circuitry is operable to report the CSI measurements of the target LTM candidate cell to the target candidate cell by reporting the CSI measurements in an uplink grant provided as part of an LTM cell switch command.

17. A method (800) performed by a source network node (300), the method comprising: obtaining (812) a channel state information, CSI, configuration from one or more layer one / layer two triggered mobility, LTM, candidate cells; transmitting (814) the CSI configuration to a user equipment; and transmitting (816) an LTM cell switch command for one of the one or more LTM candidate cells to the user equipment.

18. The method of claim 17, wherein the CSI configuration comprises an indication that the CSI configuration takes effect upon receipt of the CSI configuration.

19. The method of claim 17, wherein the CSI configuration comprises an indication that the CSI configuration takes effect upon fulfillment of a condition associated with the LTM candidate cell.

20. The method of claim 19, wherein the condition comprises any one or more of: the user equipment activates a transmission configuration indicator, TCI, state of the LTM candidate cell; the user equipment is configured with one or more LTM events and when the conditions for an event are fulfilled for the LTM candidate cell or a beam of the LTM candidate cell, it triggersthe user equipment to start acquiring CSI for the LTM candidate cell; and the user equipment is configured with at least two conditional LTM execution conditions and one of the conditional LTM execution conditions are satisfied.

21. The method of claim 17, wherein the CSI configuration comprises an indication of what CSI quantities to be computed or reported.

22. A source network node (300) comprising processing circuitry (302) operable to: obtain a channel state information, CSI, configuration from one or more layer one / layer two triggered mobility, LTM, candidate cells; transmit the CSI configuration to a user equipment (200); and transmit an LTM cell switch command for one of the one or more LTM candidate cells to the user equipment.

23. The source network node of claim 22, wherein the CSI configuration comprises an indication that the CSI configuration takes effect upon receipt of the CSI configuration.

24. The source network node of claim 22, wherein the CSI configuration comprises an indication that the CSI configuration takes effect upon fulfillment of a condition associated with the LTM candidate cell.

25. The source network node of claim 24, wherein the condition comprises any one or more of: the user equipment activates a transmission configuration indicator, TCI, state of the LTM candidate cell; the user equipment is configured with one or more LTM events and when the conditions for an event are fulfilled for the LTM candidate cell or a beam of the LTM candidate cell, it triggers the user equipment to start acquiring CSI for the LTM candidate cell; and the user equipment is configured with at least two conditional LTM execution conditions and one of the conditional LTM execution conditions are satisfied.

26. The source network node of claim 22, wherein the CSI configuration comprises an indication of what CSI quantities to be computed or reported.

27. A method (900) performed by a target network node (300), the method comprising: transmitting (912) a channel state information, CSI, configuration for a user equipment to a source network node prior to a layer one / layer two triggered mobility, LTM, cell switch of the user equipment; and receiving (916) a CSI report from the user equipment based on the CSI configuration after an LTM cell switch of the user equipment.

28. The method of claim 27, wherein the CSI configuration comprises an indication that the CSI configuration takes effect upon receipt of the CSI configuration.

29. The method of claim 27, wherein the CSI configuration comprises an indication that the CSI configuration takes effect upon fulfillment of a condition associated with a LTM candidate cell.

30. The method of claim 29, wherein the condition comprises any one or more of: the user equipment activates a transmission configuration indicator, TCI, state of the LTM candidate cell; the user equipment is configured with one or more LTM events and when the conditions for an event are fulfilled for the LTM candidate cell or a beam of the LTM candidate cell, it triggers the user equipment to start acquiring CSI for the LTM candidate cell; and the user equipment is configured with at least two conditional LTM execution conditions and one of the conditional LTM execution conditions are satisfied.

31. The method of claim 27, wherein the CSI configuration comprises an indication of what CSI quantities to be computed or reported.

32. The method of any one of claims 27-31, further comprising: transmitting (914) an uplink grant to the user equipment, the uplink grant indicating transmission resources for the user equipment to use for transmitting the CSI report to the target network node.

33. A target network node (300) comprising processing circuitry (302) operable to: transmit a channel state information, CSI, configuration for a user equipment (200) to asource network node (300) prior to a layer one / layer two triggered mobility, LTM, cell switch of the user equipment; and receive a CSI report from the user equipment based on the CSI configuration after an LTM cell switch of the user equipment.

34. The target network node of claim 33, wherein the CSI configuration comprises an indication that the CSI configuration takes effect upon receipt of the CSI configuration.

35. The target network node of claim 33, wherein the CSI configuration comprises an indication that the CSI configuration takes effect upon fulfillment of a condition associated with an LTM candidate cell.

36. The target network node of claim 35, wherein the condition comprises any one or more of: the user equipment activates a transmission configuration indicator, TCI, state of the LTM candidate cell; the user equipment is configured with one or more LTM events and when the conditions for an event are fulfilled for the LTM candidate cell or a beam of the LTM candidate cell, it triggers the user equipment to start acquiring CSI for the LTM candidate cell; and the user equipment is configured with at least two conditional LTM execution conditions and one of the conditional LTM execution conditions are satisfied.

37. The target network node of claim 33, wherein the CSI configuration comprises an indication of what CSI quantities to be computed or reported.

38. The target network node of any one of claims 33-37, the processing circuitry further operable to: transmit an uplink grant to the user equipment, the uplink grant indicating transmission resources for the user equipment to use for transmitting the CSI report to the target network node.

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