Cell switch condition evaluation

Abstract

Exemplary embodiments of the present disclosure relate to cell switch condition evaluation. In an aspect, terminal device receives, from a network device, an indication of activation or deactivation of C-LTM for at least one candidate cell or for at least one candidate beam. In case of reception of the indication of the activation of C-LTM for the at least one candidate cell or for the at least one candidate beam, the terminal device starts or continues evaluation of at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam. Alternatively, in case of reception of the indication of the deactivation of C-LTM for the at least one candidate cell or for the at least one candidate beam, the terminal device stops evaluation of the at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam.

Description

CELL SWITCH CONDITION EVALUATIONFIELD

[0001] Embodiments of the present disclosure generally relate to the field of communication, and in particular, to devices, methods, apparatuses and a computer readable storage medium for cell switch condition evaluation.BACKGROUND

[0002] A communication network can be seen as a facility that enables communications between two or more communication devices, or provides communication devices access to a data network. A mobile or wireless communication network is one example of a communication network.

[0003] Such communication networks operate in according with standards such as those provided by 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of standards are the so-called 5G (5th Generation) standards provided by 3GPP. The 3GPP has agreed that the terminal device can perform a timing advance estimation for candidate cells after configured by the network device.SUMMARY

[0004] In general, example embodiments of the present disclosure provide devices, methods, apparatuses and a computer readable storage medium for cell switch condition evaluation.

[0005] In a first aspect, there is provided a terminal device. The terminal device may comprise: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to: receive, from a network device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam; and in case of reception of the indication of the activation of C-LTM for the at least one candidate cell or for the at least one candidate beam, start or continue evaluation of at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam; or in case of reception of the indication of the deactivation of C-LTM for the at least one candidate cell or for the at least one candidate beam, stop evaluation of the at least one C-LTM condition associated with the at least one candidate cell or the at least onecandidate beam.

[0006] In a second aspect, there is provided a network device. The network device may comprise: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to: transmit, to a terminal device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam.

[0007] In a third aspect, there is provided a method. The method may comprise: receiving, from a network device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam; and in case of reception of the indication of the activation of C-LTM for the at least one candidate cell or for the at least one candidate beam, starting or continuing evaluation of at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam; or in case of reception of the indication of the deactivation of C-LTM for the at least one candidate cell or for the at least one candidate beam, stopping evaluation of the at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam.

[0008] In a fourth aspect, there is provided a method. The method may comprise: transmitting, to a terminal device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam.

[0009] In a fifth aspect, there is provided an apparatus. The apparatus may comprise: means for receiving, from a network device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam; and means for in case of reception of the indication of the activation of C-LTM for the at least one candidate cell or for the at least one candidate beam, starting or continuing evaluation of at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam; or means for in case of reception of the indication of the deactivation of C-LTM for the at least one candidate cell or for the at least one candidate beam, stopping evaluation of the at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam.

[0010] In a sixth aspect, there is provided an apparatus. The apparatus may comprise: means for transmitting, to a terminal device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam.

[0011] In a seventh aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to third or fourth aspect.

[0012] In an eighth aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus at least to perform at least the method according to third or fourth aspect.

[0013] In a ninth aspect, there is provided a terminal device. The terminal device may comprise: receiving circuitry configured to receive, from a network device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam; and performing circuitry configured to in case of reception of the indication of the activation of C-LTM for the at least one candidate cell or for the at least one candidate beam, start or continue evaluation of at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam; or in case of reception of the indication of the deactivation of C-LTM for the at least one candidate cell or for the at least one candidate beam, stop evaluation of the at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam.

[0014] In a tenth aspect, there is provided a network device. The network device may comprise transmitting circuitry configured to transmit, to a terminal device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam.

[0015] In an eleventh aspect, there is provided a terminal device. The terminal device may comprise: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to: determine activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for the at least one candidate cell or for the at least one candidate beam; and perform one of the following: evaluating at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined activation of the C-LTM, or stopping evaluation of at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined deactivation of the C-LTM.

[0016] In a twelfth aspect, there is provided a network device. The network device may comprise: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to: receive, from a terminal device, an indication that a conditional layer 1 or layer 2 triggered mobility (C-LTM)for the at least one candidate cell or for the at least one candidate beam has been activated or deactivated by the terminal device.

[0017] In a thirteenth aspect, there is provided a method. The method may comprise: determining activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C- LTM) for the at least one candidate cell or for the at least one candidate beam; and performing one of the following: evaluating at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined activation of the C-LTM, or stopping evaluation of at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined deactivation of the C-LTM.

[0018] In a fourteenth aspect, there is provided a method. The method may comprise: receiving, from a terminal device, an indication that a conditional layer 1 or layer 2 triggered mobility (C-LTM) for the at least one candidate cell or for the at least one candidate beam has been activated or deactivated by the terminal device.

[0019] In a fifteenth aspect, there is provided an apparatus. The apparatus may comprise: means for determining activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for the at least one candidate cell or for the at least one candidate beam; and means for performing one of the following: evaluating at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined activation of the C-LTM, or stopping evaluation of at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined deactivation of the C-LTM.

[0020] In a sixteenth aspect, there is provided an apparatus. The apparatus may comprise: means for receiving, from a terminal device, an indication that a conditional layer 1 or layer 2 triggered mobility (C-LTM) for the at least one candidate cell or for the at least one candidate beam has been activated or deactivated by the terminal device.

[0021] In a seventeenth aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to third or fourth aspect.

[0022] In an eighteenth aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus at least to perform at least the method according to third or fourth aspect.

[0023] In a nineteenth aspect, there is provided a terminal device. The terminal device may comprise: determining circuitry configured to determine activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for the at least one candidate cellor for the at least one candidate beam; and performing circuitry configured to perform one of the following: evaluating at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined activation of the C-LTM, or stopping evaluation of at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined deactivation of the C-LTM.

[0024] In a twentieth aspect, there is provided a network device. The network device may comprise receiving circuitry configured to receive, from a terminal device, an indication that a conditional layer 1 or layer 2 triggered mobility (C-LTM) for the at least one candidate cell or for the at least one candidate beam has been activated or deactivated by the terminal device.

[0025] It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0027] Fig. 1 illustrates an example network environment in which example embodiments of the present disclosure may be implemented;

[0028] Fig. 2A illustrates an example signaling process for cell switch condition evaluation according to some embodiments of the present disclosure;

[0029] Fig. 2B illustrates an example signaling process for cell switch condition evaluation according to some embodiments of the present disclosure;

[0030] Fig. 3 illustrates an example signaling process during the preparation phase of the C-LTM according to some embodiments of the present disclosure;

[0031] Fig. 4 illustrates an example signaling process during the early sync and C-LTM evaluation phase of the C-LTM for dynamic activation process according to some embodiments of the present disclosure;

[0032] Fig. 5 illustrates an example signaling process during the early sync and C-LTM evaluation phase of the C-LTM for dynamic deactivation process according to some embodiments of the present disclosure;

[0033] Fig. 6 illustrates an example signaling process during the execution and completion phase of the C-LTM according to some embodiments of the present disclosure;

[0034] Fig. 7 illustrates a flowchart of an example method implemented at a terminal devicein accordance with some exemplary embodiments of the present disclosure;

[0035] Fig. 8 illustrates a flowchart of an example method implemented at a terminal device in accordance with some exemplary embodiments of the present disclosure;

[0036] Fig. 9 illustrates another flowchart of an example method implemented at a network device in accordance with some exemplary embodiments of the present disclosure;

[0037] Fig. 10 illustrates another flowchart of an example method implemented at a network device in accordance with some exemplary embodiments of the present disclosure;

[0038] Fig. 11 illustrates a simplified block diagram of a device that is suitable for implementing some exemplary embodiments of the present disclosure; and

[0039] Fig. 12 illustrates a block diagram of an example of a computer-readable medium in accordance with some exemplary embodiments of the present disclosure.

[0040] Throughout the drawings, the same or similar reference numerals represent the same or similar element.DETAILED DESCRIPTION

[0041] Principles of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein may be implemented in various manners other than the ones described below.

[0042] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which the present disclosure belongs.

[0043] References in the present disclosure to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes 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 affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0044] It may be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms.These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms.

[0045] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0046] As used in this application, the term “circuitry” may refer to one or more or all of the following:(a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and(b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) with software / firmware and(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and(c) hardware circuit(s) and or processor(s), such as a microprocessor s) or a portion of a microprocessor s) that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0047] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit fora mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0048] As used herein, the term “communication network” refers to a network following any suitable communication standards, such as long term evolution (LTE), LTE-advanced (LTE-A), wideband code division multiple access (WCDMA), high-speed packet access (HSPA), narrow band Internet of things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the third generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G) communication protocols, and / or beyond. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

[0049] As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a NR NB (also referred to as a gNB), a remote radio unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology.

[0050] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE), a subscriber station (SS), a portable subscriber station, a mobile station (MS), or an access terminal (AT). The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer-premises equipment (CPE), an Internet of things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications(e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. In the following description, the terms “terminal device”, “communication device”, “terminal”, “user equipment” and “UE” may be used interchangeably.

[0051] When a user equipment (UE) moves from one cell to another cell, at some point a serving cell change needs to be performed. In some cases, the serving cell change is done by explicit radio resource control (RRC) reconfiguration signaling to trigger the synchronization of target cell based on L3 measurements report. It leads to longer latency, larger overhead, and longer interruption time than beam level mobility. Therefore, in 3GPP Release 18, a new work item on further new radio (NR) mobility enhancements, named as layer 1 (LI) / layer 2 (L2)-triggered mobility (LTM), was approved to enable a serving cell change via L1 / L2 signaling, in order to reduce the latency, overhead and interruption time.

[0052] Rel-18 LTM (L1 / L2 triggered mobility) is a mobility procedure where the network configures the UE with up to 8 candidate cells, and eventually sends a cell switch command to the UE to perform cell switch to one of those cells. Cell switch decision may be based on LI or L3 measurements reported by the UE. One of the key goals of LTM was to reduce the interruption caused by the cell switch from the L3 handover. The reduction of the interruption caused by the cell switch is achieved through different early procedures: early DL synchronization through early transmission configuration indication (TCI) state activation; early UL synchronization through physical downlink control channel (PDCCH) ordered random access channel (RACH) or UE based TA estimation; or early abstract syntax notation one (ASN.l) decoding and validity check.

[0053] L3 conditional handover is a procedure where the network configures the UE with one or more signal thresholds-based conditions for one or more cells. The UE evaluates the conditions and at the event of a condition for a cell becoming met, executes conditional handover without a handover command to this cell.

[0054] Rel-19 will introduce conditional LTM as an enhancement to the Rel-18 LTM procedure. In conditional LTM, the UE will autonomously execute cell switch to one of the candidate cells based on network-configured conditions. The details of the full procedure, including the preparation steps, are still open.

[0055] In view of the above, some embodiments of the present disclosure propose a solution for cell switch condition evaluation. Specifically, in some embodiments of the present disclosure, the terminal device receives, from a network device, an indication of activationor deactivation of C-LTM for at least one candidate cell or for at least one candidate beam. In case of reception of the indication of the activation of C-LTM for the at least one candidate cell or for the at least one candidate beam, the terminal device starts or continues evaluation of at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam. Alternatively, in case of reception of the indication of the deactivation of C-LTM for the at least one candidate cell or for the at least one candidate beam, the terminal device stops evaluation of the at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam.

[0056] Specifically, in some embodiments of the present disclosure, a terminal device determines activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C- LTM) for the at least one candidate cell or for the at least one candidate beam. Then, the terminal device performs one of the following: evaluating at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined activation of the C-LTM, or stopping evaluation of at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined deactivation of the C-LTM.

[0057] For illustrative purposes, principle and example embodiments of the present disclosure will be described below with reference to Figs. 1-12. However, it is to be noted that these embodiments are given to enable the skilled in the art to understand inventive concepts of the present disclosure and implement the solution as proposed herein, and not intended to limit scope of the present application in any way.

[0058] Fig. 1 illustrates an example network environment 100 in which example embodiments of the present disclosure may be implemented. The environment 100, which may be a part of a communication network, includes terminal devices and network devices.

[0059] As illustrated in Fig. 1, the communication network 100 may include a terminal device 110 (hereinafter may also be referred to as a user equipment (UE) 110). The communication network 100 may further include a first network device 120, which can be a source distributed unit (DU) providing a plurality of cells, and one of them can be a serving cell (for example, cell 120-1) for serving the terminal device 110 now. The communication network 100 may further include a second network device 130, which can be a target DU providing a plurality of candidate cells, and one of the candidate cells may be a target cell (for example, cell 130-1) to be switched to by the terminal device 110. The communication network 100 may further include a third network device 140, which can be the center unit (CU) for managing the source DU and the target DU.

[0060] As shown in Fig. 1 when the UE 110 moves between different cells belonging to different DUs within a same CU. In short, this scenario is called as inter-DU mobility. As shown in Fig. 1, the serving cell 120-1 belongs to the first network device 120, and the target cell 130-1 belongs to the second network device 130, and the terminal device 110 moves from the cell 120-1 to the cell 130-1. It should be understood that each DU may have many cells, and only one cell is shown for illustration, for example, there are several candidate cells for the target DU, and only one cell as a target cell is shown for the purpose of illustration.

[0061] It is to be understood that the number of network devices and terminal devices is given only for the purpose of illustration without suggesting any limitations. The system 100 may include any suitable number of network devices and / or terminal devices adapted for implementing embodiments of the present disclosure. Although not shown, it would be appreciated that one or more terminal devices may be located in the environment 100.

[0062] Communications in the network environment 100 may be implemented according to any proper communication protocol(s), comprising, but not limited to, the third generation (3G), the fourth generation (4G), the fifth generation (5G) or beyond, wireless local network communication protocols such as institute for electrical and electronics engineers (IEEE) 802.11 and the like, and / or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: multiple-input multiple-output (MIMO), orthogonal frequency division multiplexing (OFDM), time division multiplexing (TDM), frequency division multiplexing (FDM), code division multiplexing (CDM), Bluetooth, ZigBee, and machine type communication (MTC), enhanced mobile broadband (eMBB), massive machine type communication (mMTC), ultra-reliable low latency communication (URLLC), carrier aggregation (CA), dual connection (DC), and new radio unlicensed (NR- U) technologies.

[0063] For Rel-19 conditional LTM (C-LTM), procedures defined in Rel-18 LTM, which was based on network-triggered cell switch, may have to be enhanced to support UE- autonomous cell switch triggering. In addition, although only intra-CU LTM will be supported in Rel-19, further enhancements of the LTM feature to support conditional inter- CU LTM may follow in subsequent releases.

[0064] All the details of C-LTM are up to Rel-19 discussions and agreements. However, at least the baseline of conditional handover (CHO) will be reused i.e. the UE will be configured with one or more (LI or L3 based) conditions for one or more candidate cells. The conditions can be provided in the common LTM configuration or can be candidatespecific. At the event of such condition becoming met, the UE shall execute conditional LTM cell switch to a candidate cell for which the condition was met. How the conditions are defined and how the early preparation steps, DL and UL synchronization, will work for C-LTM are still open.

[0065] For example, it is not defined currently when the UE shall evaluate the condition for each candidate cell configured for C-LTM, and whether the conditions are defined based on LI or L3 measurements. However, the UE will likely have some limitations for how many cells it can evaluate the LTM condition, especially if the condition is based on LI measurements. For example, in the case of LI measurement-based condition evaluation, this limitation may further depend on the number of reference signals (RSs) or beams from a candidate cell that can be considered for evaluating the condition.

[0066] Furthermore, if the UE is evaluating the condition for all configured candidate cells, network has very little control over which cell the UE may actually perform C-LTM to, hindering the ability of the network to perform load balancing. Additionally, early synchronization may not have been performed or may not be up-to-date when the conditional cell switch condition is satisfied, resulting in a RACH-based LTM cell switch, which incurs higher interruption time.

[0067] In some cases, depending on the deployment scenario and the UE’s mobility profile, the UE may perform too frequent cell switches and the time between cell switches may be too short for successful handover completion, e.g., the path switch or the security key update may not be complete. In order to solve this issue one may think to configure a long time to trigger. In that case the condition for conditional LTM may not be met within a reasonable time from when the UE starts evaluating the condition, it will lead to UE having to continue the evaluation for an unreasonably long time without resulting in a cell switch. This might limit the benefit of CLTM. In other scenario, the most suitable target cell may change over the time the UE is configured with CLTM.

[0068] In view of the foregoing, an example signaling process for cell switch condition evaluation according to some embodiments of the present disclosure will be described with referent to Fig. 2A hereinafter. For the purpose of discussion, the communication process 200A will be described with reference to Fig. 1. It would be appreciated that although the communication process 200A has been described referring to the network environment 100 of Fig. 1, this communication process 200A may be likewise applied to other similar communication scenarios. It should be appreciated that the terminal device 201 is an example of the terminal device 110 of Fig. 1 and the network device 202 is an example ofthe first network device 120(i.e. a source DU) of Fig. 1.

[0069] As shown in Fig. 2, the network device 202 transmits (205), to the terminal device 201, an indication of activation or deactivation of C-LTM for at least one candidate cell or for at least one candidate beam. The terminal device 201 receives (210), from the network device 202, an indication of activation or deactivation of C-LTM for at least one candidate cell or for at least one candidate beam. Based on reception of the indication of the activation of C-LTM for the at least one candidate cell or for the at least one candidate beam, the terminal device 201 starts or continues (215) evaluation of at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam. Alternatively, based on reception of the indication of the deactivation of C-LTM for the at least one candidate cell or for the at least one candidate beam, the terminal device 201 stops (215) evaluation of the at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam.

[0070] In some embodiments, for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam, the indication of activation is used for an initial activation of the C-LTM, and the indication of deactivation is used for an initial deactivation of the C-LTM.

[0071] In some embodiments, the indication of the activation of the C-LTM comprises: a radio resource control (RRC) signaling during the LTM preparation phase from the network device for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam; or an activation trigger from the network device. In some embodiments, the indication of the deactivation of the C-LTM comprises: a radio resource control (RRC) signaling during the LTM preparation phase from the network device for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam; or a deactivation trigger from the network device.

[0072] In some embodiments, the RRC signaling during the LTM preparation phase is configured to indicate at least one of following: activation of the C-LTM in the case that there is a flag in an LTM-config information element (IE) for global activation or deactivation or in an LTM-candidate IE for per cell activation or deactivation, and deactivation of the C- LTM in the case that there is no the flag in the LTM-config IE or the LTM-candidate IE; activation and deactivation of the C-LTM with different values of the flag; activation and deactivation of the C-LTM as indicated by the flag after a cell switch; indicating the terminal device to perform an evaluation of at least one C-LTM condition based on an RRC reconfiguration or based on the trigger from the network device; or whether or not theterminal device to suspend the evaluation and wait for the trigger from the network device after an inter-centralized unit (CU) changes.

[0073] For example, the RRC signaling during LTM preparation phase can be used for initial (de)activation. The RRC signaling comprises e.g., a flag in the LTM-Config IE (for global (de)activation) or in the LTM-Candidate IE (for per cell (de)activation) indicating activation or activation trigger. Further, RRC signaling during LTM preparation phase may be used for initial (de)activation, e.g., a flag in the LTM-Config IE (for global (de)activation) or in the LTM-Candidate IE (for per cell (de)activation) indicating deactivation.

[0074] In one implementation, if there is no flag, the behavior is such that the CLTM is not active. In another implementation, a flag indicating either activation or deactivation correspondingly with Boolean value (true, false). In another embodiment, after a cell switch, the UE determines (de)activation of C-LTM condition evaluation as indicated by the flag. In one implementation for each LTM candidate config, along with the condition additional parameter, it may indicate UE can do evaluation from the configuration or wait for any of the triggers from the network device. Further, the flag may indicate whether UE to suspend evaluation and wait for NW trigger after Inter-CU change or no, and alternatively, this can be defined UE behavior by default.

[0075] In some embodiments, the terminal device 201 starts the evaluation of the at least one C-LTM condition for the at least one candidate cell or the at least one candidate beam for which the C-LTM is activated. In some embodiments, the C-LTM for the at least one candidate cell or the at least one candidate beam is at least one of the following: activated according to explicit configuration in the RRC signaling; deactivated by default until the activation trigger from the network device is received or until a terminal device-based timing advance (TA) estimation is obtained; or activated by default until a deactivation trigger from the network device is received or until cell switch is executed.

[0076] In some embodiments, at least one subsequent activation of the C-LTM is performed based on the activation trigger from the network device; and at least one subsequent deactivation of the C-LTM is performed based on the deactivation trigger from the network device.

[0077] In some embodiments, the RRC signaling during the LTM preparation phase further comprises a time duration of a first timer of activation of the C-LTM, and the first timer is configured to be started or restarted at reception of message from the network device for triggering the terminal device to start or continue the evaluation of the at least one C-LTM condition. Further, a duration time of the first timer is configured or specified for multiplecandidate cells or multiple candidate beams, or separately configured or specified for a candidate cell or a candidate beam. In some embodiments, the terminal device 201 starts or restarts the first timer, upon starting or continuing the evaluation of the at least one C-LTM condition; and upon expiry of the first timer, the terminal device 201 stops the evaluation of the at least one C-LTM condition which was started or continued when the first timer was started or restarted.

[0078] In some embodiments, the RRC signaling during the LTM preparation phase further comprises a time duration of a second timer for blocking subsequent C-LTM, wherein the second timer is configured to be started when a conditional cell switch is executed. In some embodiments, the terminal device 201 stops the evaluation of the at least one C-LTM condition while the second timer is running; and the terminal device 201 starts the evaluation of the at least one C-LTM condition upon expiry of the second timer.

[0079] In some embodiments, the activation trigger from the network device further comprises a transmission configuration indication (TCI) state activation command having an implicit indication of activation of the C-LTM or an explicit indication of activation of the C-LTM. In some embodiments, upon reception of the TCI state activation command, or after completion of the TCI state activation, the terminal device 201 starts or continues the evaluation of the at least one C-LTM condition that is related to a reference signal (RS) associated to an activated TCI state; or starts or continues the evaluation of multiple conditions (for example, all conditions) configured for the at least one candidate cell or the at least one candidate beam.

[0080] In some embodiments, the terminal device 201 uses the activated TCI state for which associated C-LTM condition is met to access the target cell. In some embodiments, the RS associated to the activated TCI state comprises at least one of the following: a quasi-Co- Location (QCL) information RS of TCI state; or a QCL source RS of the QCL information RS of the TCI state.

[0081] For example, according to the received TCI activation command, the terminal device 201 starts or continues evaluating the conditions that are related to the RS associated to the activated TCI state, where the RS may be one of the QCL info RS of TCI state synchronization signal block or channel state information reference signal (SSB / CSLRS) or the QCL source RS (SSB / CSLRS) of the QCL info RS of TCI state. In addition, the NW tells the UE it is allowed to perform conditional cell switch using the activated TCI state or in case of multiple activated TCI states, any of the activated TCI states. The condition evaluation may begin after processing the MAC-CE (which typically takes 3ms), aftersending the acknowledgment (e.g., Hybrid Automatic Repeat Request Acknowledgement (HARQ ACK)) associated with the MAC-CE reception, or after the completion of the TCI activation (e.g., following the TCI activation delay). The S-DU can send the TCI state info to the C-DU as well.

[0082] In some embodiments, the activation trigger from the network device comprises a PDCCH order having an implicit indication of activation of the C-LTM or an explicit indication of activation of the C-LTM. In some embodiments, the terminal device 201 uses a TCI state associated with an RS index in the PDCCH order to access the target cell. In some embodiments, the terminal device 201 starts or continues the evaluation of the at least one C-LTM condition, upon reception of the PDCCH order, after sending a physical randomaccess channel (PRACH) transmission, or after receiving a timing advance (TA) value associated with the RACH triggered by the PDCCH order. In some embodiments, the at least one C-LTM condition is related to a RS indicated in the PDCCH order or related to multiple conditions (for example, all conditions) configured for the at least one candidate cell or the at least one candidate beam.

[0083] For example, upon reception of a PDCCH order, the terminal device 201 starts or continues evaluating the conditions that are related to the RS (SSB or CSLRS) given in the PDCCH order. In addition, the TCI state, that is associated with the RS index in the PDCCH order, can be used by the UE to access the target cell, and the S-DU can send the TCI state info to the C-DU as well, or C-DU may determine this information from the physical random access channel (PRACH) reception incurred due the PDCCH ordered PRACH transmission associated with the RS. The condition evaluation may begin after receiving the PDCCH order, after sending a PRACH transmission, or after receiving the TA value associated with the RACH triggered by the PDCCH order.

[0084] In some embodiments, the activation trigger from the network device further comprises a TA information message from the network device. In some embodiments, upon reception of the TA information, or upon reception of the TA information along with an explicit indication for C-LTM activation, the terminal device 201 starts or continues the evaluation of the at least one conditions related to a RS indicated in a PDCCH order to which the TA information message corresponds; or starts or continues the evaluation of multiple conditions (for example, all conditions) configured for the at least one candidate cell or the at least one candidate beam.

[0085] For example, upon reception of a TA information message (or random-access response, RAR), the terminal device 201 starts or continues evaluating the conditions that arerelated to the RS given in PDCCH order to which the TA information message (or RAR) corresponds.

[0086] In some embodiments, the activation trigger from the network device further comprises a C-LTM activation medium access control-control element (MAC-CE) comprising at least one of the following: a cell identification to indicate activation of the C- LTM for a specific cell; an indication of a beam for beam-specific condition activation; or an indication instructing the terminal device to activate the C-LTM for intra-CU candidate cells or the inter-CU candidate cells. In some embodiments, upon reception of the C-LTM activation MAC-CE, after processing the C-LTM activation MAC-CE, or after sending an acknowledgement associated with reception of the C-LTM activation MAC-CE, the terminal device 201 starts or continues the evaluation of C-LTM conditions as indicated by the C- LTM activation MAC-CE.

[0087] For example, a new C-LTM (de)activation MAC-CE may indicate activation, cell ID, or intra- / inter-CU activation, or beam indication. The condition evaluation may begin after processing the MAC-CE (which typically takes 3ms) or after sending the acknowledgment (e.g., HARQ ACK) associated with the MAC-CE reception. In a further embodiment, the transmission of the C-LTM (de)activation MAC-CE from the S-DU may be triggered by a message from the CU / candidate CU to the S-DU / S-CU (and then S-CU to S- DU) indicating that C-LTM for a candidate cell is (de)activated. Such a triggering message may be sent for load balancing purposes.

[0088] In some embodiments, the deactivation trigger from the network device comprises a TCI state activation or deactivation command for a candidate cell with previously activated C-LTM. In some embodiments, the TCI state activation or deactivation command for the candidate cell with previously activated C-LTM comprises candidate cell TCI state activation command for another beam. In some embodiments, for beam-specific C-LTM activation, in the case that a plurality of newly activated TCI states are different from the TCI states that were previously activated, the terminal device 201 starts or continues the evaluation of conditions for a RS associated to the plurality of newly activated TCI states and stop the evaluation of conditions for a RS associated with previously activated TCI states which are not included in the plurality of newly activated TCI states.

[0089] For example, the deactivation trigger may be TCI state activation / deactivation command for candidate cell for which TCI states were previously activated. For beamspecific C-LTM activation, if the new activated TCI states are different from the earlier activated TCI states, the UE shall continue evaluating the conditions for the RS associated tothe most recently activated TCI states. When all TCI states for the candidate cell are deactivated, the UE stops evaluating all conditions for this candidate cell.

[0090] In some embodiments, the deactivation trigger may be TCI state activation command, PDCCH order, TA information for another candidate cell. This condition may also be restricted through UE capability to evaluate candidate cell conditions simultaneously. If the UE is capable to evaluate conditions for up to Ml candidate cells, the UE will perform condition evaluation (beam- or cell-specific) for all up to Ml candidate cells for which it received TCI state activation command, PDCCH order or TA information. If UE receives TCI state activation command, PDCCH order or TA information for more than Ml cells, the latest Ml cells are considered for condition evaluation.

[0091] In some embodiments, the deactivation trigger from the network device comprises a TCI state activation command, a PDCCH order, or a TA information for M2 RSs not associated with previously activated conditions. For beam-specific activation, the UE capability may be indicated in terms of number of RSs or the number of conditional LTM evaluations (e.g., M4) that can be performed simultaneously. Upon receiving a TCI state activation command, a PDCCH order, or a TA information for M2 RSs not associated with previously activated conditions while M3 conditions are activated, wherein the sum of M2 and M3 is greater than M4, the UE may select the ‘M4’ RSs, associated with the latest TCI state activation command, a latest PDCCH order or a latest TA information for condition evaluation.

[0092] In some embodiments, for beam-specific activation, the deactivation trigger from the network device comprises a PDCCH order or a TA information having an RS not associated to currently evaluated or active conditions for a candidate cell with previously activated C-LTM.

[0093] For example, for beam-specific activation, the deactivation trigger may be a PDCCH order, a TA information reception for the same candidate cell with an RS not associated to the conditions it is currently evaluating based on earlier TCI state activation, PDCCH order, TA information reception. The UE continues to evaluate the conditions based on the latest PDCCH order and the latest TA information.

[0094] In some embodiments, the deactivation trigger from the network device comprises a C-LTM deactivation MAC-CE comprising at least one of the following: a cell identification to indicate deactivation of the C-LTM for a specific cell; an indication of a beam for beamspecific condition deactivation; or an indication instructing the terminal device to deactivate the C-LTM for the intra-CU candidate cells or the inter-CU candidate cells.

[0095] In some embodiments, upon reception of the C-LTM deactivation MAC-CE, after processing the C-LTM deactivation MAC-CE, or after sending an acknowledgement associated with reception of the C-LTM deactivation MAC-CE, the terminal device 201 stops the evaluation as indicated by the C-LTM deactivation MAC-CE. For example, a new C- LTM (de)activation MAC-CE may indicate the deactivation of the C-LTM.

[0096] In some embodiments, the deactivation trigger from the network device comprises an RRC reconfiguration or deconfiguration message, and the terminal device 201 stops evaluation of C-LTM conditions upon receiving the RRC reconfiguration or deconfiguration message. For example, upon reception of RRC reconfiguration or deconfiguration, the UE stops evaluating the C-LTM conditions upon receiving an RRC re- or deconfiguration message.

[0097] In some embodiments, the deactivation trigger from the network device comprises a cell switch command or handover command; and the terminal device 201 stops evaluation of C-LTM conditions for both inter-CU cells and intra-CU cells; or stops evaluation of C- LTM conditions for inter-CU cells and continues evaluation of C-LTM conditions for intra- CU cells. For example, upon the reception of a cell switch command or handover command, the deactivation is performed and the deactivation can be global, i.e. UE stops evaluating all C-LTM conditions. Alternatively, the UE only stops the evaluation of the conditions for only for inter-CU cells, i.e., UE stops evaluating C-LTM conditions for inter-CU cells, but continues evaluating C-LTM conditions for intra-CU cells.

[0098] Although the C-LTM activation and deactivation can be based on the indication from the network device, the C-LTM activation and deactivation can also be based on UE action. Hereinafter, the embodiments of the C-LTM activation or deactivation based on an UE action will be described.

[0099] an example signaling process 200B for cell switch condition evaluation according to some embodiments of the present disclosure will be described with referent to Fig. 2B hereinafter. For the purpose of discussion, the communication process 200B will be described with reference to Fig. 1.

[0100] For example, as shown in Fig. 2B, the terminal device 201 determines (205) activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for the at least one candidate cell or for the at least one candidate beam. Further, the terminal device 201 performs (210) one of the following evaluating at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined activation of the C-LTM, or stopping evaluation of at least one C-LTM condition for the atleast one candidate cell or for the at least one candidate beam based on the determined deactivation of the C-LTM. Then, the terminal device 201 transmits (215) an indication that a C-LTM for the at least one candidate cell or for the at least one candidate beam has been activated or deactivated by the terminal device, and the network device 202 receives (220) the indication that the C-LTM for the at least one candidate cell or for the at least one candidate beam has been activated or deactivated by the terminal device.

[0101] In some embodiments, the terminal device 201 autonomously activates at least one transmission configuration indication (TCI) state; and upon activation of a TCI state, informs the network device that the TCI state has been activated. In some embodiments, the terminal device 201 determines the activation of the C-LTM upon activation of the TCI state; and starts or continues the evaluation of the at least one C-LTM condition that is related to a reference signal (RS) associated to an activated TCI state; or starting or continuing the evaluation of one or more conditions configured for the at least one candidate cell or the at least one candidate beam. For example, if the UE is configured to autonomously activate TCI states, upon autonomous activation of a TCI state, it starts / continues evaluating C-LTM conditions that are related to the RS associated to the activated TCI state. The UE may inform the source node about the autonomous TCI state activation which in turn may inform the target node.

[0102] In some embodiments, the terminal device 201 performs a timing advance (TA) estimation; and informs the network device that the TA estimation has been obtained. The terminal device 201 determines the activation of the C-LTM upon obtaining of a TA value; and starts or continues the evaluation of the at least one C-LTM condition that is related to a RS used for the TA estimation.

[0103] For example, the UE action-based activation trigger may be that the UE performs UE-based TA estimation, and if UE-based TA estimation is configured and upon obtaining a UE-based TA estimate, the UE starts or continues evaluating the conditions that are related to the (candidate cell) RS(s) used for UE-based TA estimation.

[0104] In some embodiments, the terminal device performs RRC configuration processing for the at least one candidate cell. In some embodiments, the RRC configuration processing for the at least one candidate cell comprises at least one of: Abstract Syntax Notation One (ASN.1) decoding of the RRC configuration for the at least one candidate cell; and validity check of the RRC configuration for the at least one candidate cell. In some embodiments, the terminal device 201 determines activation of the C-LTM upon performing the RRC configuration processing; and performs the evaluation by starting or continuing theevaluation of the C-LTM conditions for the at least one candidate cell for which the RRC configuration processing is performed.

[0105] For example, the UE action-based activation trigger may be that the UE performs a fast or early RRC configuration processing, and the UE starts or continues evaluation of the C-LTM conditions of a candidate cell upon performing fast or early RRC configuration processing for the candidate cell.

[0106] In some embodiments, the terminal device 201 may switch from dual connectivity to single connectivity, and then the terminal device 201 may determine activation of the C- LTM based on determining that the terminal device switches from dual connectivity to the single connectivity; and start evaluation of C-LTM conditions for one or more candidate cells or for cells for which the activation of the C-LTM has occurred while being in dual connectivity. That is to say, the UE action-based activation trigger may be that the UE switches from dual connectivity to single connectivity.

[0107] In some embodiments, the UE action-based deactivation comprises the expiry of a timer. In these embodiments, the UE receives an indication of a first timer from the network device, wherein the first timer is started or restarted by the terminal device upon TCI state activation or upon obtaining a TA estimate for triggering the terminal device to start or continue the evaluation of the at least one C-LTM condition. In these embodiments, the terminal device 201 upon expiry of the first timer, determines deactivation of the C-LTM; and stops the evaluation of the at least one C-LTM condition which was started or continued when the first timer was started or restarted. In some embodiments, a time duration of the first timer is configured or specified; a common time duration is configured or specified for multiple candidate cells; or a time duration is configured separately for a candidate cell. In some embodiments, the terminal device 201 upon expiry of a second timer for considering valid TCI state activation, determines the deactivation of the C-LTM; and stops the evaluation of the at least one C-LTM condition based on the determined deactivation.

[0108] For example, if the deactivation trigger is based on network indication, the timer can be configured to start at RRC configuration, TCI state activation command, PDCCH order or TA information reception, while if the deactivation trigger is based on the UE action, the timer may be configured to start upon TCI state activation or upon obtaining a TA estimate. The time duration of the timer may be configured or specified. A common time duration may be configured / specified for all candidate cells or it may be configured separately for each candidate cell. In another alternative the RAN4 timers to consider valid TCI state activation can de-activate the CLTM monitoring.

[0109] In some embodiments, the terminal device is further caused to autonomously perform a TCI state activation for a candidate cell with previously activated C-LTM. In these embodiments, for beam-specific C-LTM activation, in the case that a plurality of newly activated TCI states are different from the TCI states that were previously activated, the terminal device 201 starts or continues the evaluation of conditions for a RS associated to the plurality of newly activated TCI states and stops the evaluation of conditions for a RS associated with previously activated TCI states which are not included in the plurality of newly activated TCI states.

[0110] For example, the UE action-based deactivation trigger may be autonomous TCI state activation for candidate cell for which TCI states were previously activated. For beamspecific C-LTM activation, if the new activated TCI states are different from the earlier activated TCI states, the UE shall continue evaluating the conditions for the RS associated to the most recently activated TCI states. Further, when all TCI states for the candidate cell are deactivated UE stops evaluating all conditions for this candidate cell.

[0111] In some embodiments, the terminal device 201 autonomously performs a TCI state activation or a TA estimation for a candidate cell which is not previously activated while Ml candidate cells are activated, wherein Ml is a maximum number of cells for which the terminal device is able to evaluate conditions simultaneously. In these embodiments, the terminal device 201 determines deactivation of the C-LTM upon autonomously perform a TCI state activation or a TA estimation for more than Ml candidate cells; and performs the evaluation by performing cell-specific condition evaluation for up to latest Ml candidate cells. In these embodiments, the terminal device 201 further autonomously performs a TCI state activation or a TA estimation for M2 RSs not associated with previously activated conditions while M3 conditions are activated, wherein the sum of M2 and M3 is greater than M4 and M4 is a maximum number of RSs or a maximum number of C-LTM evaluations that can be performed simultaneously, and the terminal device 201 determines deactivation of the C-LTM upon autonomously performing the TCI state activation or the TA estimation for M2 RSs; and for beam-specific activation, performs condition evaluation for up to M4 RSs associated with a latest TCI state activation or a latest TA estimation.

[0112] For example, the UE action-based deactivation trigger may be UE-based TA estimation or UE-autonomous TCI state activation for another candidate cell. This condition may also be restricted through UE capability to evaluate candidate cell conditions simultaneously. If UE is capable to evaluate conditions for up to M candidate cells, the UE will perform condition evaluation (beam- or cell-specific) for all up to M candidate cells forwhich it performed UE-based TA estimation or autonomous TCI state activation. If UE performs UE-based TA estimation or autonomous TCI activation for more than M cells, the latest M cells are considered for condition evaluation. In one option, for beam-specific activation, the UE capability may be indicated in terms of number of RSs or the number of conditional LTM evaluations (e.g., M) that can be performed simultaneously. The UE may select the ‘M’ RSs, associated with the latest TCI state activation or latest TA estimation for condition evaluation.

[0113] In some embodiments, the terminal device 201 autonomously performs a TA estimation which has an RS not associated to currently evaluated or active conditions for a candidate cell with previously activated C-LTM. In these embodiments, the terminal device 201 determines deactivation of the C-LTM when the terminal device-based TA estimation has the RS not associated to currently evaluated or active conditions, and performs the evaluation by continuing the evaluation for the candidate cell with previously activated C- LTM based on a latest terminal device-based TA estimation.

[0114] For example, for beam-specific activation, the UE action-based deactivation trigger may be UE-based TA estimation for the same candidate cell with an RS not associated to the conditions it is currently evaluating based on earlier UE-based TA estimation. The UE continues to evaluate the conditions based on the latest UE-based TA estimation.

[0115] In some embodiments, the terminal device 201 determines deactivation of the C- LTM upon determining that a TA becomes invalid; and stops evaluation of the conditions for the at least one candidate cell for which the TA becomes invalid. In these embodiments, the terminal device 201 determines deactivation of the C-LTM based on determining that the terminal device has not reported a beam for the at least one candidate cell for a duration starting from a last measurement repot; and performs the evaluation by stopping the evaluation for the at least one candidate cell, and the measurement report is a layer 1 (LI) report or a layer 3 (L3) report.

[0116] For example, the UE-acti on-based deactivation trigger may be the time from last measurement report, and if UE has not reported a beam of a candidate cell for a duration UE can stop evaluating the execution condition for that cell.

[0117] In some embodiments, the terminal device 201 determines deactivation of the C- LTM based on determining that the terminal device switches from single connectivity to dual connectivity; and stops the evaluation of one or more C-LTM conditions. That is to say, the UE action-based deactivation trigger may be that the UE switches from single connectivity to dual connectivity.

[0118] Hereinafter, the details of the signaling and actions associated with the present application will be discussed with reference to Figs. 3 to 6, in which exemplary message sequence charts for each of the C-LTM phases (for example, preparation phase, early sync and C-LTM evaluation phase, execution and completion phase) are provided separately.

[0119] Fig. 3 illustrates an example signaling process during the preparation phase of the C-LTM according to some embodiments of the present disclosure. It should be understood that the UE 310 may be example of the terminal device 110 of Fig. 1, and the source DU (S- DU) 320 may be an example of the first network devicel20 of Fig. 1, and the target DU (T- DU) 330 may be an example of the second network device 130 of Fig. 1, and the CU 340 may be an example of the third network device 140 of Fig. 1.

[0120] As shown in Fig. 3, at steps 1 to 7, the UE 310 will send the measurement report to the CU 340 via the source DU 320, and the CU 340 decides to prepare T-DU / cell(s) 330 for LTM. The CU 340 proceeds with the UE context setup / modification procedures.

[0121] As shown in Fig. 3, at step 8, the CU 340 generates the RRC reconfiguration. For example, the RRC reconfiguration comprises, for example, CSI resource and report configuration, RRC configuration of prepared cells, early sync configuration, and C-LTM configuration. The C-LTM configuration comprises, for example, a) conditional cell switch execution conditions (for the initial and the subsequent cell switches); b) an indication of activation / deactivation of C-LTM; c) a time duration of a timer for deactivation of C-LTM; and d) a time duration of a timer for blocking subsequent C-LTM.

[0122] The indication of the of activation / deactivation of C-LTM may be associated with all candidate cells, i.e., indicating activation or deactivation of C-LTM for all candidate cells or cell-specific. In some examples, such an indication may be useful to set the initial (de)activation of C-LTM. Subsequent (de)activation of C-LTM for the configured candidates may not be performed with an RRC message, and it may be performed with one of the (de)activation triggers from the network, for example, PDCCH order, a new C-LTM (de)activation MAC-CE, TCI activation- based evaluation of condition, TA (timing advance) status-based evaluation of condition, and the like which will be explained in the below with reference to Fig. 4 and Fig. 5.

[0123] The RRC signaling during LTM preparation phase for initial (de)activation may be for example, a flag in the LTM-Config information element (IE) for global (de)activation (i.e. for all candidate cells) or a flag in the LTM-Candidate IE for per cell (de)activation, and the flag may indicate activation of the C-LTM or activation trigger of the C-LTM. As for activation trigger of the C-LTM, it may mean that the UE may determine activation of C-LTM condition evaluation upon reception of a trigger signaling.

[0124] In one implementation, if there is no flag, the behavior is such that the C-LTM is not active. In another implementation, a flag may indicate either activation or deactivation correspondingly with Boolean value (true, false). In another embodiment, after a cell switch, the UE determines (de)activation of C-LTM condition evaluation as indicated by the flag.

[0125] In one implementation, for each LTM candidate config, along with the condition additional parameter that indicates UE can do evaluation from the configuration or wait for any of the trigger from the network, for example, PDCCH order, a new C-LTM (de)activation MAC-CE, TCI activation- based evaluation of condition, TA (timing advance) status-based evaluation of condition, and the like. In one implementation, flag may indicate whether UE to suspend evaluation and wait for NW trigger as described below after Inter-CU change or not, or this can be defined UE behavior by default.

[0126] The timer for deactivation of C-LTM is configured to start / restart at TCI state activation command, PDCCH order or TA information reception, which triggers the UE to start / continue evaluating C-LTM conditions. Upon expiration of the timer, the UE stops evaluating the conditions which it started / continued evaluating when the timer was started / restarted. The time duration of the timer may be configured or specified. A common time duration may be configured / specified for all candidate cells, or it may be configured separately for each candidate cell.

[0127] The timer for blocking subsequent C-LTM is configured to start when a conditional cell switch is executed. While the timer is running, the UE stops evaluating C-LTM conditions. In one embodiment, the UE stops evaluating all C-LTM conditions. In another embodiment, the UE stops evaluating C-LTM conditions for inter-CU cells. Upon expiration of the timer, the UE may start evaluating C-LTM conditions.

[0128] As shown in Fig. 3, at steps 9 and 10, the CU 340 transmits the DL RRC message transfer to the source DU 320, and the source DU 320 transmits the RRC reconfiguration including the indication of activation or deactivation of C-LTM and timer(s) configuration to the UE 310. That is to say, the CU 340 generates and sends the RRC reconfiguration message to the UE 310 via the source DU 320.

[0129] In the process 300 as shown in Fig. 3, the RRC signaling may be used for load balancing purposes. For example, the network may want to restrict the UE from autonomously switching to a cell that is initially overloaded, and therefore, the network may provide an explicit C-LTM deactivation indication for that cell in the RRC message. Later,when that cell becomes less loaded, the network can send a MAC CE indicating activation of C-LTM for that cell.

[0130] As shown in Fig. 3, at steps 11 to 12, the UE 310 sends the RRCReconfigurationComplete message to the CU 340 via the source DU 320.

[0131] Fig. 4 illustrates an example signaling process during the early sync and C-LTM evaluation phase of the C-LTM for dynamic activation process according to some embodiments of the present disclosure. It should be understood that the UE 410 may be example of the terminal device 110 of Fig. 1, and the source DU (S-DU) 420 may be an example of the first network devicel20 of Fig. 1, and the target DU (T-DU) 430 may be an example of the second network device 130 of Fig. 1, and the CU 440 may be an example of the third network device 140 of Fig. 1.

[0132] As shown in Fig. 4, at step 13, The UE 410 starts evaluating the configured C-LTM conditions for cells for which C-LTM is activated, if any. The following options are considered: activation according to explicit configuration in the RRC reconfiguration message, i.e., according to the indication in at steps 8-10, b) as shown in Fig. 3; deactivation of all conditions until further signaling is received or until UE-based TA estimate is obtained, if UE-based TA estimation is configured for a candidate cell; or activation of all conditions until further signaling is received or conditional cell switch is executed.

[0133] As shown in Fig. 4, at step 14, the UE 410 may send a L1 / L3 measurement report to the serving DU / CU. At step 15, based on the received L1 / L3 measurement report, the serving DU / CU may decide to trigger early synchronization of the UE to one or more of the candidate cells. In the following steps, the proposed C-LTM dynamic activation methods are discussed.

[0134] As shown in Fig. 4, at step 16, which is related to TCI activation command (option 1), and upon reception of a TCI activation command (implicit activation indication) or upon reception of a TCI activation command with an explicit indication for C-LTM activation, the UE 410 starts / continues evaluating the conditions that are related to the RS associated to the activated TCI state, where the RS may be one of: the QCL info RS of TCI state (SSB / CSL RS) or the QCL source RS (SSB / CSI-RS) of the QCL info RS of TCI state. Alternatively, the UE 410 may start / continue evaluating all conditions configured for this candidate cell. In addition, the NW tells the UE it is allowed to perform conditional cell switch using the activated TCI state or in case of multiple activated TCI states, any of the activated TCI states.

[0135] As shown in Fig. 4, at step 17, which is related to the PDCCH order (option 2), and upon reception of a PDCCH order (implicit activation indication) or upon reception of aPDCCH order with an explicit indication for C-LTM activation, the UE 410 may start / continue evaluating the conditions that are related to the RS given in the PDCCH order. Alternatively, the UE 410 may start / continue evaluating all conditions configured for this candidate cell. In addition, the TCI state associated with the RS index in the PDCCH order can be used by the UE to access the target cell (S-DU can send the TCI state info to the C- DU as well).

[0136] As shown in Fig. 4, at steps 19-20, which is related to TA information message (or random access response (RAR)) (option 3), and after transmission of a random access preamble for early TA acquisition in Step 18, the UE 410 receives the TA estimated by the target. The UE 410 may receive the TA information either directly from the target 430 (via a RAR) or indirectly from the source 420 (via a TA information message or a RAR). Upon reception of the TA information or upon reception of TA information along with an explicit indication for C-LTM activation, the UE 410 starts / continues evaluating the conditions that are related to the RS given in PDCCH order to which the TA information message (or RAR) corresponds. Alternatively, the UE 410 may start / continue evaluating all conditions configured for this candidate cell.

[0137] As shown in Fig. 4, at step 21, which is related to UE-based TA estimation (option 4), if UE-based TA estimation is configured for a candidate cell and upon obtaining a UE- based TA estimate, the UE 410 starts / continues evaluating the conditions that are related to the (candidate cell) RS(s) used for UE-based TA estimation. Alternatively, the UE 410 may start / continue evaluating all conditions configured for this candidate cell. The UE may inform the source DU that it has obtained a UE-based TA estimate in Step 22.

[0138] As shown in Fig. 4, at step 23, which is related to autonomous TCI state activation (option 5), if the UE is configured to autonomously activate TCI states and upon activation of a TCI state, the UE 410 starts / continues evaluating C-LTM conditions as described in method 1 (Step 16). The UE 410 may inform the source DU that it has activated the said TCI state in step 24.

[0139] As shown in Fig. 4, step 25 is related to a new C-LTM (de)activation MAC-CE (option 6), and a new C-LTM (de)activation MAC-CE is defined and may be sent from the source DU to the UE. At step 25, upon reception of the MAC-CE, the UE 410 starts / continues C-LTM condition evaluation as indicated. In one embodiment, the MAC-CE may include a cell ID to indicate activation of C-LTM for a specific cell and may optionally include an indication of a beam for beam-specific condition activation. In an alternative embodiment, the MAC-CE may include an indication instructing the UE to (de)activate C-LTM for intra-or inter-CU candidate cells.

[0140] As shown in Fig. 4, at step 26, which is related to fast / early RRC configuration processing (option 7), the UE 410 may start / continue evaluation of the C-LTM conditions of a candidate cell upon performing fast / early RRC configuration processing for the candidate cell.

[0141] As shown in Fig. 4, step 27 is related to the combination of options 1-7 (option 8). To enforce DL sync, UL sync and / or early RRC processing, the UE 410 may start / continue evaluating C-LTM conditions associated with a cell / beam when a combination of DL sync- and UL sync-related methods among options 1-7 occur.

[0142] As shown in Fig. 4, at step 28, which is related to switch from dual connectivity to single connectivity (option 9), if the UE 410 switches to single connectivity, it may start evaluating C-LTM conditions for all candidate cells or for cells for which one of the above activation methods have occurred while being in dual connectivity.

[0143] Upon starting / continuing evaluating the C-LTM conditions according to the methods or options 1 to 9 described above, the UE 410 may start / restart the C-LTM activation timer in Step 29. The time duration of the timer may be configured or specified. A common time duration may be configured / specified for all candidate cells or it may be configured separately for each candidate cell

[0144] As shown in Fig. 4, at step 30, the source DU 420 sends (via the CU 440) to the target DU 430 an indication that C-LTM has been activated for this UE for a specific cell and optionally for a specific beam. This allows the candidate target DU to anticipate the arrival of the UE and optionally activate CG(s) provided to the UE. In an inter-CU setup, the following message flow including the proposed indication is required: a) S-DU -> S-CU, b) S-CU -> T-CU, c) T-CU -> T-DU.

[0145] Hereinafter, C-LTM dynamic deactivation method will be described with reference to Fig. 5. Fig. 5 illustrates an example signaling process during the early sync and C-LTM evaluation phase of the C-LTM for dynamic deactivation process according to some embodiments of the present disclosure. It should be understood that the UE 510 may be example of the terminal device 110 of Fig. 1, and the source DU (S-DU) 520 may be an example of the first network devicel20 of Fig. 1, and the target DU (T-DU) 530 may be an example of the second network device 130 of Fig. 1, and the CU 540 may be an example of the third network device 140 of Fig. 1.

[0146] As shown in Fig. 5, at step 32, which is related to C-LTM activation timer expiry (option 1), upon expiry of the C-LTM activation timer, the UE 510 stops evaluating theconditions it started / continued evaluating when the timer was started / restarted.

[0147] As shown in Fig. 5, steps 33-35 are related TCI state activation / deactivation command or autonomous TCI state activation for candidate cell for which TCI states were previously activated (option 2). For beam-specific C-LTM activation, if the new activated TCI states are different from the earlier activated TCI states, the UE shall continue evaluating the conditions for the RS associated to the N most recently activated TCI states and stop evaluating the conditions for the rest, where N may be up to UE capability. When all earlier activated TCI states for the candidate cell are deactivated UE stops evaluating all conditions for this candidate cell.

[0148] As shown in Fig. 5, step 36 is related to TCI state activation command, PDCCH order, TA information, UE-based estimation or UE-autonomous TCI state activation for another candidate cell. This condition may also be restricted through UE capability to evaluate candidate cell conditions simultaneously. If UE is capable to evaluate conditions for up to M candidate cells, the UE will perform condition evaluation (beam- or cell-specific) for all up to M candidate cells for which it received TCI state activation command, PDCCH order, TA information or performed UE-based TA estimation or autonomous TCI state activation. If UE receives TCI state activation command, PDCCH order or TA information or performs UE-based TA estimation or autonomous TCI activation for more than M cells, the latest M cells are considered for condition evaluation. In one option, for beam-specific activation, the UE capability may be indicated in terms of number of RSs or the number of conditional LTM evaluations (e.g., M) that can be performed simultaneously. The UE may select the ‘M’ RSs, associated with the latest TCI state activation or PDCCH order for condition evaluation.

[0149] As shown in Fig. 5, step 37 is related to a PDCCH order, TA information reception or UE-based TA estimation for the same candidate cell with an RS not associated to the conditions it is currently evaluating based on earlier TCI state activation, PDCCH order, TA information reception or UE-based TA estimation. This deactivation method is applicable only for beam-specific C-LTM (de)activation. The UE continues to evaluate the conditions based on the latest PDCCH order, latest TA information reception or latest UE-based TA estimation.

[0150] As shown in Fig. 5, at step 38, it is related to that TA becomes invalid, and then the UE stops evaluating C-LTM conditions for a candidate cell for which the TAbecomes invalid, where invalidity may be determined via time alignment timer expiry or using signal strength measurements.

[0151] As shown in Fig. 5, at step 39, it is related to a new C-LTM (de)activation MAC-CE indicating deactivation. As shown in Fig. 5, at step 40, it is related to RRC re- or deconfiguration, and the UE stops evaluating the C-LTM conditions upon receiving an RRC re- or deconfiguration message.

[0152] As shown in Fig. 5, at step 41, it is related to time from last measurement report, and if UE has not reported a beam of a candidate cell for a duration, UE can stop evaluating the execution condition for that cell. The report can be a LI or L3 report.

[0153] As shown in Fig. 5, at step 42, when the UE switches to dual connectivity, it stops evaluating all C-LTM conditions. At step 42, the UE 510 stops the evaluation of C-LTM conditions for determined cell or beam. As shown in Fig. 5, at step 44, the source DU 520 sends (via the CU 540) to the target DU 530 an indication that C-LTM has been deactivated for this UE for a specific cell and optionally for a specific beam. This allows the candidate target DU to deactivate CG(s) provided to the UE. In an inter-CU setup, the following message flow including the proposed indication is required: a) S-DU -> S-CU, b) S-CU -> T-CU, c) T-CU -> T-DU.

[0154] Hereinafter, execution and completion phase will be described with reference to Fig. 6. Fig. 6 illustrates an example signaling process during the execution and completion phase of the C-LTM according to some embodiments of the present disclosure. It should be understood that the UE 610 may be example of the terminal device 110 of Fig. 1, and the source DU (S-DU) 620 may be an example of the first network devicel20 of Fig. 1, and the target DU (T-DU) 630 may be an example of the second network device 130 of Fig. 1, and the CU 640 may be an example of the third network device 140 of Fig. 1.

[0155] As shown in Fig. 6, at step 47, if a C-LTM condition is satisfied, a conditional cell switch to the corresponding target cell is triggered. The UE applies the target RRC configuration. As shown in Fig. 6, at step 48, the UE 610 optionally performs random access to the target cell, if it does not have a valid TA.

[0156] As shown in Fig. 6, at steps 49-50, the UE 610 sends an RRC reconfiguration complete message to the CU (via the target / new serving DU). As shown in Fig. 6, at steps 51-53, the CU 610 sends to the source DU a command to release (or modify, if source DU is a candidate) the UE context and subsequently path switch is performed.

[0157] As shown in Fig. 6, at step 54, it should be noted that this step 54 may be performed any time after step 46, i.e., before steps 48-50), the UE 510 deactivates C-LTM condition evaluation upon cell switch and optionally starts the subsequent C-LTM blocking timer. The condition deactivation may be global, i.e., theUE stops evaluating conditions for all cells,or applicable to inter-CU cells (i.e., the UE continues evaluating (previously activated) conditions for cells that are controlled by the same CU as the new serving cell and stops evaluating conditions for the rest).

[0158] As shown in Fig. 6, at step 55, the C-LTM for subsequent conditional cell switches may be reactivated as described in steps 16-26.

[0159] When condition evaluation begins as proposed in section 6, the UE shall be able to complete the conditional cell switch within a cell switch delay that is starting from the event (network signal) that triggers the condition evaluation.

[0160] C-LTM cell switch delay may then be equal to the time from receiving the triggering signal and the time UE sends the first UL on the target cell. The delay may be defined to comprise for example the following parameters:DC-LTM—Tsignal_proc + TeventDU + T measure TLTM RRC-processing Tj rM-processing + TfirstSSB + TSSB -proc + TLTM IU,Where:Tsignai_proc depends on the message type and may be for example 3 ms + Tharq if the signal is a MAC-CE message, the UE would start evaluating the condition after this time (after processing the trigger signal / command or / and sending the acknowledgment for the processed trigger signal / command);TeventDU is the uncertainty time until the CLTM condition becomes met;Tmeasure is the time within which the UE shall realize the condition is met and may comprise at least LI or L3 measurement period;TLTM RRc-proeessing is the time for ASN.l decoding and validity check;TLTM -processing is the time for UE processing, for example applying the target cell parameters;TfirstRs is the time for DL synchronization and may equal to the time until the first SSB associated to the target TCI state;TRs-proc is the time for SSB processing; andTLTM iu is the interruption uncertainty which may equal to time until RACH preamble transmission for RACH-based cell switch and time until first UL transmission for RACH- less cell switch.

[0161] The value of the listed parameters may vary or be zero, and not all parameters may be included in the delay. There may also be some additional parameters that are not listed here. However, the basic principle of cell switch being the time from the event that triggers CLTM evaluation (such as UE receiving the triggering signal) until the UE sends the first UL(RACH preamble or first UL transmission) on the target cell remains.

[0162] In Rel-18 network energy saving feature, the conditional evaluation is linked to NES mode of the serving cell. In other words, the conditional evaluation for the events will be triggered only when serving cell is in NES mode. Similar triggering can be considered for CLTM, where criteria such as availability of timing advance and early downlink synchronization may be used. This way, LTM can benefit from the increased robustness of conditional cell switch execution without compromising on interruption time during cell switch. Therefore, it is a Proposal: Network triggering of condition evaluation is supported. FFS options to achieve network control. In view of the foregoing, some embodiments of the present disclosure propose solution for above proposal.

[0163] If the network wants to allow conditional LTM to be triggered towards the candidate cells for which early TA acquisition and TCI state activation is completed, the event definition need not include candidate resource set information. It can be implicitly formed on completion of the above steps. Therefore, there is a Proposal: For CLTM, implicit triggering of condition evaluation for a candidate cell based on Early-TA acquisition and Early-TCI state activation is considered. In view of the foregoing, some embodiments of the present disclosure propose solution for above proposal.

[0164] Fig. 7 shows a flowchart of an example method 700 implemented at a terminal device (for example, the terminal device 110) in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 700 will be described from the perspective of the terminal device 110 with reference to Fig. 1.

[0165] At block 710, the terminal device receives, from a network device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam.

[0166] Tat block 720, the terminal device in case of reception of the indication of the activation of C-LTM for the at least one candidate cell or for the at least one candidate beam, starts or continues evaluation of at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam; or in case of reception of the indication of the deactivation of C-LTM for the at least one candidate cell or for the at least one candidate beam, stops evaluation of the at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam.

[0167] In some embodiments, for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam, the indication of activation is used for an initial activation of the C-LTM, and the indication of deactivation is used for an initialdeactivation of the C-LTM.

[0168] In some embodiments, the indication of the activation of the C-LTM comprises: a radio resource control (RRC) signaling during the LTM preparation phase from the network device for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam; or an activation trigger from the network device.

[0169] In some embodiments, the indication of the deactivation of the C-LTM comprises: a radio resource control (RRC) signaling during the LTM preparation phase from the network device for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam; or a deactivation trigger from the network device.

[0170] In some embodiments, the RRC signaling during the LTM preparation phase is configured to indicate at least one of following: activation of the C-LTM in the case that there is a flag in an LTM-config information element (IE) for global activation or deactivation or in an LTM-candidate IE for per cell activation or deactivation, and deactivation of the C- LTM in the case that there is no the flag in the LTM-config IE or the LTM-candidate IE; activation and deactivation of the C-LTM with different values of the flag; activation and deactivation of the C-LTM as indicated by the flag after a cell switch; indicating the terminal device to perform an evaluation of at least one C-LTM condition based on an RRC reconfiguration or based on the trigger from the network device; or whether or not the terminal device to suspend the evaluation and wait for the trigger from the network device after an inter-centralized unit (CU) changes.

[0171] In some embodiments, the terminal device starts the evaluation of the at least one C-LTM condition for the at least one candidate cell or the at least one candidate beam for which the C-LTM is activated, and the C-LTM for the at least one candidate cell or the at least one candidate beam is at least one of the following: activated according to explicit configuration in the RRC signaling; deactivated by default until the activation trigger from the network device is received or until a terminal device-based timing advance (TA) estimation is obtained; or activated by default until a deactivation trigger from the network device is received or until cell switch is executed.

[0172] In some embodiments, at least one subsequent activation of the C-LTM is performed based on the activation trigger from the network device; and at least one subsequent deactivation of the C-LTM is performed based on the deactivation trigger from the network device. In some embodiments, the RRC signaling during the LTM preparation phase further comprises a time duration of a first timer of activation of the C-LTM, and the first timer is configured to be started or restarted at reception of message from the network device fortriggering the terminal device to start or continue the evaluation of the at least one C-LTM condition, and a duration time of the first timer is configured or specified for multiple candidate cells or multiple candidate beams, or separately configured or specified for a candidate cell or a candidate beam. In some embodiments, the terminal device starts or restarts the first timer, upon starting or continuing the evaluation of the at least one C-LTM condition; and upon expiry of the first timer, stops the evaluation of the at least one C-LTM condition which was started or continued when the first timer was started or restarted.

[0173] In some embodiments, the RRC signaling during the LTM preparation phase further comprises a time duration of a second timer for blocking subsequent C-LTM, wherein the second timer is configured to be started when a conditional cell switch is executed. In some embodiments, the terminal device stops the evaluation of the at least one C-LTM condition while the second timer is running; and starts the evaluation of the at least one C-LTM condition upon expiry of the second timer.

[0174] In some embodiments, the activation trigger from the network device further comprises a transmission configuration indication (TCI) state activation command having an implicit indication of activation of the C-LTM or an explicit indication of activation of the C-LTM. upon reception of the TCI state activation command, or after completion of the TCI state activation, the terminal device starts or continues the evaluation of the at least one C- LTM condition that is related to a reference signal (RS) associated to an activated TCI state; or starts or continues the evaluation of multiple conditions configured for the at least one candidate cell or the at least one candidate beam. In some embodiments, the terminal device uses the activated TCI state for which associated C-LTM condition is met to access the target cell. In some embodiments, the RS associated to the activated TCI state comprises at least one of the following: a quasi-Co-Location (QCL) information RS of TCI state; or a QCL source RS of the QCL information RS of the TCI state.

[0175] In some embodiments, the activation trigger from the network device comprises a physical downlink control channel (PDCCH) order having an implicit indication of activation of the C-LTM or an explicit indication of activation of the C-LTM. In some embodiments, the terminal device uses a transmission configuration indication (TCI) state associated with an RS index in the PDCCH order to access the target cell.

[0176] In some embodiments, the terminal device starts or continues the evaluation of the at least one C-LTM condition, upon reception of the PDCCH order, after sending a physical random-access channel (PRACH) transmission, or after receiving a timing advance (TA) value associated with the RACH triggered by the PDCCH order, and the at least one C-LTMcondition is related to a RS indicated in the PDCCH order or related to multiple conditions configured for the at least one candidate cell or the at least one candidate beam.

[0177] In some embodiments, the activation trigger from the network device further comprises a TAinformation message from the network device. In some embodiments, upon reception of the TA information, or upon reception of the TA information along with an explicit indication for C-LTM activation, the terminal device starts or continues the evaluation of the at least one conditions related to a RS indicated in a PDCCH order to which the TA information message corresponds; or starts or continues the evaluation of multiple conditions configured for the at least one candidate cell or the at least one candidate beam.

[0178] In some embodiments, the activation trigger from the network device further comprises a C-LTM activation medium access control-control element (MAC-CE) comprising at least one of the following: a cell identification to indicate activation of the C- LTM for a specific cell; an indication of a beam for beam-specific condition activation; or an indication instructing the terminal device to activate the C-LTM for intra-CU candidate cells or the inter-CU candidate cells.

[0179] In some embodiments, the terminal device upon reception of the C-LTM activation MAC-CE, after processing the C-LTM activation MAC-CE, or after sending an acknowledgement associated with reception of the C-LTM activation MAC-CE, starts or continues the evaluation of C-LTM conditions as indicated by the C-LTM activation MAC- CE.

[0180] In some embodiments, the deactivation trigger from the network device comprises a TCI state activation or deactivation command for a candidate cell with previously activated C-LTM. In some embodiments, the TCI state activation or deactivation command for the candidate cell with previously activated C-LTM comprises candidate cell TCI state activation command for another beam, and the terminal device for beam-specific C-LTM activation, in the case that a plurality of newly activated TCI states are different from the TCI states that were previously activated, starts or continues the evaluation of conditions for a RS associated to the plurality of newly activated TCI states and stops the evaluation of conditions for a RS associated with previously activated TCI states which are not included in the plurality of newly activated TCI states.

[0181] In some embodiments, the deactivation trigger from the network device comprises a TCI state activation command, a PDCCH order, or a TA information for a candidate cell which is not previously activated while Ml candidate cells are activated, wherein Ml is a maximum number of cells for which the terminal device is able to evaluate conditionssimultaneously, and the terminal device performs cell-specific condition evaluation for up to latest Ml candidate cells for which TCI state was activated, PDCCH order was received or TA information was acquired.

[0182] In some embodiments, the deactivation trigger from the network device comprises a TCI state activation command, a PDCCH order, or a TA information for M2 RSs not associated with previously activated conditions. For beam-specific activation, the UE capability may be indicated in terms of number of RSs or the number of conditional LTM evaluations (e.g., M4) that can be performed simultaneously. Upon receiving a TCI state activation command, a PDCCH order, or a TA information for M2 RSs not associated with previously activated conditions while M3 conditions are activated, wherein the sum of M2 and M3 is greater than M4, the terminal device, for beam-specific activation, performs condition evaluation for up to M4 RSs associated with a latest TCI state activation, a latest PDCCH order or a latest TA information.

[0183] In some embodiments, for beam-specific activation, the deactivation trigger from the network device comprises a PDCCH order or a TA information having an RS not associated to currently evaluated or active conditions for a candidate cell with previously activated C-LTM. In some embodiments, the deactivation trigger from the network device comprises a C-LTM deactivation MAC-CE comprising at least one of the following: a cell identification to indicate deactivation of the C-LTM for a specific cell; an indication of a beam for beam-specific condition deactivation; or an indication instructing the terminal device to deactivate the C-LTM for the intra-CU candidate cells or the inter-CU candidate cells. In some embodiments, the terminal device upon reception of the C-LTM deactivation MAC-CE, after processing the C-LTM deactivation MAC-CE, or after sending an acknowledgement associated with reception of the C-LTM deactivation MAC-CE, stops the evaluation as indicated by the C-LTM deactivation MAC-CE.

[0184] In some embodiments, the deactivation trigger from the network device comprises an RRC reconfiguration or deconfiguration message, and the terminal device stops evaluation of C-LTM conditions upon receiving the RRC reconfiguration or deconfiguration message.

[0185] In some embodiments, the deactivation trigger from the network device comprises a cell switch command or handover command; and the terminal device stops evaluation of C-LTM conditions for both inter-CU cells and intra-CU cells; or stops evaluation of C-LTM conditions for inter-CU cells and continue evaluation of C-LTM conditions for intra-CU cells.

[0186] Fig. 8 shows a flowchart of an example method 800 implemented at a terminal device (for example, the terminal device 110) in accordance with some embodiments of thepresent disclosure. For the purpose of discussion, the method 800 will be described from the perspective of the terminal device 110 with reference to Fig. 1.

[0187] At block 810, the terminal device determines activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for the at least one candidate cell or for the at least one candidate beam. At block 820, the terminal device performs one of the following: evaluating at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined activation of the C-LTM, or stopping evaluation of at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined deactivation of the C-LTM.

[0188] In some embodiments, the terminal device autonomously activates at least one transmission configuration indication (TCI) state; and upon activation of a TCI state, informs the network device that the TCI state has been activated. In some embodiments, the terminal device determines the activation of the C-LTM upon activation of the TCI state; and performs the evaluation by: starting or continuing the evaluation of the at least one C-LTM condition that is related to a reference signal (RS) associated to an activated TCI state; or starting or continuing the evaluation of one or more conditions configured for the at least one candidate cell or the at least one candidate beam.

[0189] In some embodiments, the terminal device performs a timing advance (TA) estimation; and informs the network device that the TA estimation has been obtained. In some embodiments, the terminal device determines the activation of the C-LTM upon obtaining of a TA value; and starts or continues the evaluation of the at least one C-LTM condition that is related to a RS used for the TA estimation.

[0190] In some embodiments, the terminal device performs RRC configuration processing for the at least one candidate cell. In some embodiments, RRC configuration processing for the at least one candidate cell comprises at least one of: Abstract Syntax Notation One (ASN.1) decoding of the RRC configuration for the at least one candidate cell; and validity check of the RRC configuration for the at least one candidate cell. In some embodiments, the terminal device determines activation of the C-LTM upon performing the RRC configuration processing; and performs the evaluation by starting or continuing the evaluation of the C- LTM conditions for the at least one candidate cell for which the RRC configuration processing is performed.

[0191] In some embodiments, the terminal device switches from dual connectivity to single connectivity. In some embodiments, the terminal device determines activation of the C-LTM based on determining that the terminal device switches from dual connectivity to thesingle connectivity; and starts evaluation of C-LTM conditions for one or more candidate cells or for cells for which the activation of the C-LTM has occurred while being in dual connectivity.

[0192] In some embodiments, the terminal device receives an indication of a first timer from the network device, wherein the first timer is started or restarted by the terminal device upon TCI state activation or upon obtaining a TA estimate for triggering the terminal device to start or continue the evaluation of the at least one C-LTM condition. In some embodiments, the terminal device upon expiry of the first timer determines deactivation of the C-LTM; and stops the evaluation of the at least one C-LTM condition which was started or continued when the first timer was started or restarted. In some embodiments, a time duration of the first timer is configured or specified; a common time duration is configured or specified for multiple candidate cells; or a time duration is configured separately for a candidate cell. In some embodiments, the terminal device upon expiry of a second timer for considering valid TCI state activation, determines the deactivation of the C-LTM; and stops the evaluation of the at least one C-LTM condition based on the determined deactivation.

[0193] In some embodiments, the terminal device autonomously performs a TCI state activation for a candidate cell with previously activated C-LTM. In some embodiments, for beam-specific C-LTM activation, in the case that a plurality of newly activated TCI states are different from the TCI states that were previously activated, the terminal device starts or continues the evaluation of conditions for a RS associated to the plurality of newly activated TCI states and stops the evaluation of conditions for a RS associated with previously activated TCI states which are not included in the plurality of newly activated TCI states.

[0194] In some embodiments, the terminal device autonomously performs a TCI state activation or a TA estimation for a candidate cell which is not previously activated while Ml candidate cells are activated, wherein Ml is a maximum number of cells for which the terminal device is able to evaluate conditions simultaneously. In some embodiments, the terminal device determines deactivation of the C-LTM upon autonomously performed a TCI state activation or a TA estimation for more than Ml candidate cells; and performs the evaluation by performing cell-specific condition evaluation for up to latest Ml candidate cells. In some embodiments, the terminal device autonomously performs a TCI state activation or a TA estimation for M2 RSs not associated with previously activated conditions while M3 conditions are activated, wherein the sum of M2 and M3 is greater than M4 and M4 is a maximum number of RSs or a maximum number of C-LTM evaluations that can be performed simultaneously. In some embodiments, the terminal device determinesdeactivation of the C-LTM upon autonomously performing the TCI state activation or the TA estimation for more than M4 RSs; and for beam-specific activation, performs condition evaluation for up to M4 RSs associated with a latest TCI state activation or a latest TA estimation.

[0195] In some embodiments, the terminal device autonomously performs a TA estimation which has an RS not associated to currently evaluated or active conditions for a candidate cell with previously activated C-LTM. In some embodiments, the terminal device determines deactivation of the C-LTM when the terminal device-based TA estimation has the RS not associated to currently evaluated or active conditions, and performs the evaluation by continuing the evaluation for the candidate cell with previously activated C-LTM based on a latest terminal device-based TA estimation.

[0196] In some embodiments, the terminal device determines deactivation of the C-LTM upon determining that a TA becomes invalid; and stops evaluation of the conditions for the at least one candidate cell for which the TA becomes invalid.

[0197] In some embodiments, the terminal device determines deactivation of the C-LTM based on determining that the terminal device has not reported a beam for the at least one candidate cell for a duration starting from a last measurement repot; and performs the evaluation by stopping the evaluation for the at least one candidate cell. In some embodiments, the measurement report is a layer 1 (LI) report or a layer 3 (L3) report.

[0198] In some embodiments, the terminal device determines deactivation of the C-LTM based on determining that the terminal device switches from single connectivity to dual connectivity; and stops the evaluation of one or more C-LTM conditions.

[0199] Fig. 9 shows a flowchart of an example method 900 implemented at a network device (for example, the first network device 120) in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 900 will be described from the perspective of first network device 120 with reference to Fig. 1.

[0200] As shown in Fig. 9, at block 1010, the network device transmits, to a terminal device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam.

[0201] In some embodiments, for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam, the indication of activation is used for an initial activation of the C-LTM, and the indication of deactivation is used for an initial deactivation of the C-LTM.

[0202] In some embodiments, the indication of the activation of the C-LTM comprises: aradio resource control (RRC) signaling during the LTM preparation phase from the network device for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam; or an activation trigger from the network device. In some embodiments, the indication of the deactivation of the C-LTM comprises: a radio resource control (RRC) signaling during the LTM preparation phase from the network device for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam; or a deactivation trigger from the network device.

[0203] In some embodiments, the RRC signaling during the LTM preparation phase is configured to indicate at least one of following: activation of the C-LTM in the case that there is a flag in an LTM-config information element (IE) for global activation or deactivation or in an LTM-candidate IE for per cell activation or deactivation, and deactivation of the C- LTM in the case that there is no the flag in the LTM-config IE or the LTM-candidate IE; activation and deactivation of the C-LTM with different values of the flag; activation and deactivation of the C-LTM as indicated by the flag after a cell switch; indicating the terminal device to perform an evaluation of at least one C-LTM condition based on an RRC reconfiguration or based on the trigger from the network device; or whether or not the terminal device to suspend the evaluation and wait for the trigger from the network device after an inter-centralized unit (CU) changes.

[0204] In some embodiments, at least one subsequent activation of the C-LTM is based on the activation trigger from the network device; and at least one subsequent deactivation of the C-LTM is based on the deactivation trigger from the network device.

[0205] In some embodiments, the RRC signaling during the LTM preparation phase further comprises a time duration of a first timer of activation of the C-LTM, the first timer is to be started or restarted by the terminal device at reception of message from the network device for triggering the terminal device to start or continue evaluation of at least one C-LTM condition, and a duration time of the first timer is configured by the network device or specified for multiple candidate cells or multiple candidate beams or separately configured or specified for a candidate cell or a candidate beam.

[0206] In some embodiments, the RRC signaling during the LTM preparation phase further comprises a time duration of a second timer for blocking subsequent C-LTM, and wherein the second timer is to be started by the terminal device when a conditional cell switch is executed. In some embodiments, the activation trigger from the network device further comprises a transmission configuration indication (TCI) state activation command having an implicit indication of activation of the C-LTM or an explicit indication of activation of theC-LTM.

[0207] In some embodiments, at least one C-LTM condition for evaluation is related to a reference signal (RS) associated to an activated TCI state, or multiple conditions configured for the at least one candidate cell or the at least one candidate beam; and the RS associated to the activated TCI state comprises at least one of the following: a quasi-Co-Location (QCL) information RS of TCI state; a QCL source RS of the QCL information RS of the TCI state

[0208] In some embodiments, the activation trigger from the network device comprises a physical downlink control channel (PDCCH) order having an implicit indication of activation of the C-LTM or an explicit indication of activation of the C-LTM; and at least one C-LTM condition for evaluation is related to a reference signal (RS) indicated in the PDCCH order or related to multiple conditions configured for the at least one candidate cell or the at least one candidate beam.

[0209] In some embodiments, the activation trigger from the network device further comprises a TA information message from the network device, and at least one L-LTM condition for evaluation is related to a RS indicated in a PDCCH order to which the TA information message corresponds or multiple conditions configured for the at least one candidate cell or the at least one candidate beam.

[0210] In some embodiments, the activation trigger from the network device further comprises a C-LTM activation medium access control-control element (MAC-CE) comprising at least one of the following: cell identification to indicate activation of the C- LTM for a specific cell; indication of a beam for beam-specific condition activation; or indication instructing the terminal device to activate the C-LTM for intra-CU candidate cells or the inter-CU candidate cells.

[0211] In some embodiments, at least one C-LTM condition for evaluation is related to conditions as indicated by the C-LTM activation MAC-CE. In some embodiments, the deactivation trigger from the network device comprises a TCI state activation or deactivation command for a candidate cell with previously activated C-LTM; and the network device transmits, to the terminal device, the TCI state activation or deactivation command for the candidate cell with previously activated C-LTM.

[0212] In some embodiments, the TCI state activation or deactivation command for the candidate cell with previously activated C-LTM comprises candidate cell TCI state activation command for another beam, wherein for beam-specific C-LTM activation, in the case that a plurality of newly activated TCI states are different from the TCI states that were previously activated, the evaluation of conditions for a RS associated to the plurality of newly activatedTCI states is started or continued by the terminal device, and the evaluation of conditions for a RS associated with previously activated TCI states which are not included in the plurality of newly activated TCI states is stopped by the terminal device.

[0213] In some embodiments, the deactivation trigger from the network device comprises a TCI state activation command, a PDCCH order, or a TA information for a candidate cell which is not previously activated while Ml candidate cells are activated, wherein Ml is a maximum number of cells for which the terminal device is able to evaluate conditions simultaneously, and the network device transmits, to the terminal device, the TCI state activation command, the PDCCH order, or the TA, and cell-specific condition evaluation for up to latest Ml candidate cells are performed by the terminal device for which TCI state was activated, PDCCH order was received or TA information was acquired..

[0214] In some embodiments, the deactivation trigger from the network device comprises a TCI state activation command, a PDCCH order, or a TA information for M2 RSs not associated with previously activated conditions while M3 conditions are activated, wherein the sum of M2 and M3 is greater than M4 and M4 is a maximum number of RSs or a maximum number of C-LTM evaluations that can be performed simultaneously; and the network device transmits, to the terminal device, the TCI state activation command, the PDCCH order, or the TA information for M2 RSs, wherein condition evaluation for up to M4 RSs associated with a latest TCI state activation, a latest PDCCH order or a latest TA information is performed by the terminal device.

[0215] In some embodiments, for beam-specific activation, the deactivation trigger from the network device comprises a PDCCH order or a TA information having an RS not associated to currently evaluated or active conditions for a candidate cell with previously activated C-LTM. In some embodiments, the deactivation trigger from the network device comprises a C-LTM deactivation MAC-CE comprising at least one of the following: cell identification to indicate deactivation of the C-LTM for a specific cell; indication of a beam for beam-specific condition deactivation; or indication instructing the terminal device to deactivate the C-LTM for the intra-CU candidate cells or the inter-CU candidate cells.

[0216] In some embodiments, the network device transmits, to the terminal device, the C- LTM deactivation MAC-CE, and evaluation of C-LTM conditions is stopped by the terminal device as indicated by the C-LTM deactivation MAC-CE.

[0217] In some embodiments the deactivation trigger from the network device comprises an RRC reconfiguration or deconfiguration message, and the network device transmits, to the terminal device, the RRC reconfiguration or deconfiguration message, and evaluation ofC-LTM conditions is stopped by the terminal device upon reception of the RRC reconfiguration or deconfiguration message.

[0218] In some embodiments, the deactivation trigger from the network device comprises a cell switch command or handover command; and the network device transmits, to the terminal device, the cell switch command or handover command, and based on the cell switch command or handover command, evaluation of multiple C-LTM condition or evaluation of C-LTM conditions for inter-CU cells is stopped by the terminal device, and evaluation of C- LTM conditions for intra-CU cells is continued by the terminal device.

[0219] In some embodiments, the network device transmits, to a target distributed unit (T- DU) via a centralized unit (CU), a notification of activation of the C-LTM for a first specific cell or a first specific beam in the case that evaluation of C-LTM condition for the first specific cell or the first specific beam is stated or continued by the terminal device; or transmits, to the T-DU via the CU, a notification of deactivation of the C-LTM for a second specific cell or a second specific beam in the case that evaluation of C-LTM condition for the second specific cell or the second specific beam is stopped by the terminal device.

[0220] Fig. 10 shows a flowchart of an example method 1000 implemented at a network device (for example, the first network device 120) in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1000 will be described from the perspective of first network device 120 with reference to Fig. 1.

[0221] As shown in Fig. 10, at block 1010, the network device receives, from a terminal device, an indication that a conditional layer 1 or layer 2 triggered mobility (C-LTM) for the at least one candidate cell or for the at least one candidate beam has been activated or deactivated by the terminal device.

[0222] In some embodiments, the network device receives, from the terminal device, the indication that the C-LTM has been activated by the terminal device, in the case that the activation of the C-LTM is determined by the terminal device for autonomously activating at least one TCI state upon activation of the TCI state, and evaluation of at least one C-LTM condition that is related to a reference signal (RS) associated to an activated TCI state is started or continued by the terminal device based on the activation of the C-LTM.

[0223] In some embodiments, the network device receives, from the terminal device, the indication that the C-LTM has been activated by the terminal device, in the case that activation of the C-LTM is determined by the terminal device upon obtaining of a TA value, and evaluation of at least one C-LTM condition that is related to a RS used for the TA estimation is started or continued by the terminal device based on the obtaining of the TAestimate.

[0224] In some embodiments, the network device receives, from the terminal device, the indication that the C-LTM has been activated by the terminal device, in the case that activation of the C-LTM is determined by the terminal device upon performing a RRC configuration processing, and evaluation of C-LTM conditions for which the RRC configuration processing is started or continued by the terminal device.

[0225] In some embodiments, the network device receives, from the terminal device, the indication that the C-LTM has been activated by the terminal device, in the case that activation of the C-LTM is determined by the terminal device based on determining that the terminal device switches from dual connectivity to the single connectivity, and evaluation of C-LTM conditions for one or more candidate cells or for cells for which the activation of the C-LTM has occurred while being in dual connectivity is started or continued by the terminal device.

[0226] In some embodiments, the network device transmits, an indication of a first timer to the terminal device, wherein the first timer is started or restarted by the terminal device upon reception of message from the network device for triggering the terminal device to start or continue evaluation of at least one C-LTM condition, upon TCI state activation or upon obtaining a TA estimate; and time duration of the first timer is configured or specified; a common time duration is configured or specified for one or more candidate cells; or a time duration is configured separately for each candidate cell.

[0227] In some embodiments, the network device receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device, in the case that the deactivation of the C-LTM is determined by the terminal device upon expiry of the first timer, and evaluation of at least one C-LTM condition which was started or continued when the first timer is started or restarted is stopped by the terminal device.

[0228] In some embodiments, the network device receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device, in the case that the deactivation of the C-LTM is determined by the terminal device upon expiry of a second timer for considering valid TCI state activation.

[0229] In some embodiments, the network device receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device for autonomously performing a TCI state activation for a candidate cell with previously activated C-LTM, in the case that for beam-specific C-LTM activation, a plurality of newly activated TCI states are different from the TCI states that were previously activated, the evaluation of conditionsfor a RS associated to the plurality of newly activated TCI states is started or continued by the terminal device and the evaluation of conditions for a RS associated with previously activated TCI states which are not included in the plurality of newly activated TCI states is stopped by the terminal device.

[0230] In some embodiments, the network device receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device for autonomously performing a TCI state activation or a TA estimation for a candidate cell which is not previously activated while Ml candidate cells are activated, wherein Ml is a maximum number of cells for which the terminal device is able to evaluate conditions simultaneously.

[0231] In some embodiments, the network device receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device for autonomously performing autonomously perform a TCI state activation or a TA estimation for M2 RSs not associated with previously activated conditions while M3 conditions are activated, wherein the sum of M2 and M3 is greater than M4 and M4 is a maximum number of RSs or a maximum number of C-LTM evaluations that can be performed simultaneously.

[0232] In some embodiments, the network device receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device for autonomously performing a TA estimation which has an RS not associated to currently evaluated or active conditions for a candidate cell with previously activated C-LTM.

[0233] In some embodiments, the network device receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device for determining deactivation of the C-LTM upon determining that a TA becomes invalid.

[0234] In some embodiments, the network device receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device in the case that deactivation of the C-LTM is determined by the terminal device based on determining that the terminal device has not reported a beam for the at least one candidate cell for a duration starting from a last measurement report, and the measurement report is an LI report or an L3 report.

[0235] In some embodiments, the network device receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device in the case that deactivation of the C-LTM is determined by the terminal device based on determining that the terminal device switches from single connectivity to a dual connectivity.

[0236] In some embodiments, an apparatus capable of performing any of operations of the method 700 (for example, the terminal device 110) may include means for performing therespective steps of the method 700. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0237] In some embodiments, the apparatus comprises means for receiving, from a network device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam, and means for in case of reception of the indication of the activation of C-LTM for the at least one candidate cell or for the at least one candidate beam, starting or continuing evaluation of at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam; or in case of reception of the indication of the deactivation of C-LTM for the at least one candidate cell or for the at least one candidate beam, stopping evaluation of the at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam.

[0238] In some embodiments, the apparatus further comprises means for starting the evaluation of the at least one C-LTM condition for the at least one candidate cell or the at least one candidate beam for which the C-LTM is activated, and the C-LTM for the at least one candidate cell or the at least one candidate beam is at least one of the following: activated according to explicit configuration in the RRC signaling; deactivated by default until the activation trigger from the network device is received or until a terminal device-based timing advance (TA) estimation is obtained; or activated by default until a deactivation trigger from the network device is received or until cell switch is executed.

[0239] In some embodiments, the apparatus further comprises means for starting or restarting the first timer, upon starting or continuing the evaluation of the at least one C-LTM condition; and upon expiry of the first timer, stopping the evaluation of the at least one C- LTM condition which was started or continued when the first timer was started or restarted.

[0240] In some embodiments, the RRC signaling during the LTM preparation phase further comprises a time duration of a second timer for blocking subsequent C-LTM, wherein the second timer is configured to be started when a conditional cell switch is executed. In some embodiments, the apparatus further comprises means for stopping the evaluation of the at least one C-LTM condition while the second timer is running; and starting the evaluation of the at least one C-LTM condition upon expiry of the second timer.

[0241] In some embodiments, the activation trigger from the network device further comprises a transmission configuration indication (TCI) state activation command having an implicit indication of activation of the C-LTM or an explicit indication of activation of the C-LTM, and the apparatus further comprises means for upon reception of the TCI stateactivation command, or after completion of the TCI state activation, starting or continuing the evaluation of the at least one C-LTM condition that is related to a reference signal (RS) associated to an activated TCI state; or means for starting or continuing the evaluation of multiple conditions configured for the at least one candidate cell or the at least one candidate beam. In some embodiments, the apparatus further comprises means for using the activated TCI state for which associated C-LTM condition is met to access the target cell. In some embodiments, the RS associated to the activated TCI state comprises at least one of the following: a quasi-Co-Location (QCL) information RS of TCI state; or a QCL source RS of the QCL information RS of the TCI state.

[0242] In some embodiments, the activation trigger from the network device comprises a physical downlink control channel (PDCCH) order having an implicit indication of activation of the C-LTM or an explicit indication of activation of the C-LTM. In some embodiments, the apparatus further comprises means for using a transmission configuration indication (TCI) state associated with an RS index in the PDCCH order to access the target cell.

[0243] In some embodiments, the apparatus further comprises means for starting or continuing the evaluation of the at least one C-LTM condition, upon reception of the PDCCH order, after sending a physical random-access channel (PRACH) transmission, or after receiving a timing advance (TA) value associated with the RACH triggered by the PDCCH order, and the at least one C-LTM condition is related to a RS indicated in the PDCCH order or related to multiple conditions configured for the at least one candidate cell or the at least one candidate beam.

[0244] In some embodiments, the activation trigger from the network device further comprises a TAinformation message from the network device. In some embodiments, upon reception of the TA information, or upon reception of the TA information along with an explicit indication for C-LTM activation, the apparatus further comprises means for starting or continuing the evaluation of the at least one conditions related to a RS indicated in a PDCCH order to which the TA information message corresponds; or means for starting or continuing the evaluation of multiple conditions configured for the at least one candidate cell or the at least one candidate beam.

[0245] In some embodiments, the activation trigger from the network device further comprises a C-LTM activation medium access control-control element (MAC-CE) comprising at least one of the following: a cell identification to indicate activation of the C- LTM for a specific cell; an indication of a beam for beam-specific condition activation; or an indication instructing the terminal device to activate the C-LTM for intra-CU candidate cellsor the inter-CU candidate cells.

[0246] In some embodiments, the apparatus further comprises means for upon reception of the C-LTM activation MAC-CE, after processing the C-LTM activation MAC-CE, or after sending an acknowledgement associated with reception of the C-LTM activation MAC-CE, starting or continuing the evaluation of C-LTM conditions as indicated by the C-LTM activation MAC-CE.

[0247] In some embodiments, the deactivation trigger from the network device comprises a TCI state activation or deactivation command for a candidate cell with previously activated C-LTM. In some embodiments, the TCI state activation or deactivation command for the candidate cell with previously activated C-LTM comprises candidate cell TCI state activation command for another beam, and the apparatus further comprises means for: for beam-specific C-LTM activation, in the case that a plurality of newly activated TCI states are different from the TCI states that were previously activated, starting or continuing the evaluation of conditions for a RS associated to the plurality of newly activated TCI states and stopping the evaluation of conditions for a RS associated with previously activated TCI states which are not included in the plurality of newly activated TCI states.

[0248] In some embodiments, the deactivation trigger from the network device comprises a TCI state activation command, a PDCCH order, or a TA information for candidate cell which is not previously activated while Ml candidate cells are activated, wherein Ml is a maximum number of cells for which the terminal device is able to evaluate conditions simultaneously, and the apparatus further comprises means for performing cell-specific condition evaluation for up to latest Ml candidate cells for which TCI state was activated, PDCCH order was received or TA information was acquired..

[0249] In some embodiments, the deactivation trigger from the network device comprises a TCI state activation command, a PDCCH order, or a TA information for M2 RSs not associated with previously activated conditions while M3 conditions are activated, wherein the sum of M2 and M3 is greater than M4 and M4 is a maximum number of RSs or a maximum number of C-LTM evaluations that can be performed simultaneously, and the apparatus further comprises means for performing condition evaluation for up to M4 RSs associated with a latest TCI state activation, a latest PDCCH order or a latest TA information for beam-specific activation.

[0250] In some embodiments, for beam-specific activation, the deactivation trigger from the network device comprises a PDCCH order or a TA information having an RS not associated to currently evaluated or active conditions for a candidate cell with previouslyactivated C-LTM. In some embodiments, the deactivation trigger from the network device comprises a C-LTM deactivation MAC-CE comprising at least one of the following: a cell identification to indicate deactivation of the C-LTM for a specific cell; an indication of a beam for beam-specific condition deactivation; or an indication instructing the terminal device to deactivate the C-LTM for the intra-CU candidate cells or the inter-CU candidate cells. In some embodiments, the apparatus further comprises means for stopping the evaluation as indicated by the C-LTM deactivation MAC-CE upon reception of the C-LTM deactivation MAC-CE, after processing the C-LTM deactivation MAC-CE, or after sending an acknowledgement associated with reception of the C-LTM deactivation MAC-CE.

[0251] In some embodiments, the deactivation trigger from the network device comprises an RRC reconfiguration or deconfiguration message, and the apparatus further comprises means for stopping evaluation of C-LTM conditions upon receiving the RRC reconfiguration or deconfiguration message.

[0252] In some embodiments, the deactivation trigger from the network device comprises a cell switch command or handover command; and the apparatus further comprises means for stopping evaluation of C-LTM conditions for both inter-CU cells and intra-CU cells; or means for stopping evaluation of C-LTM conditions for inter-CU cells and continue evaluation of C-LTM conditions for intra-CU cells.

[0253] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 700. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

[0254] In some embodiments, an apparatus capable of performing any of operations of the method 800 (for example, the terminal device 110) may include means for performing the respective steps of the method 800. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0255] In some embodiments, the apparatus comprises means for determining activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for the at least one candidate cell or for the at least one candidate beam; and means for the terminal device performing one of the following: evaluating at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined activation of the C-LTM, or stopping evaluation of at least one C-LTM condition for the at least one candidate cell or for the at least one candidate beam based on the determined deactivation ofthe C-LTM.

[0256] In some embodiments, the apparatus further comprises means for autonomously activating at least one transmission configuration indication (TCI) state; and upon activation of a TCI state, informing the network device that the TCI state has been activated. In some embodiments, means for determining determines the activation of the C-LTM upon activation of the TCI state; and means for performing performs the evaluation by: starting or continuing the evaluation of the at least one C-LTM condition that is related to a reference signal (RS) associated to an activated TCI state; or starting or continuing the evaluation of one or more conditions configured for the at least one candidate cell or the at least one candidate beam.

[0257] In some embodiments, the apparatus further comprises means for performing a timing advance (TA) estimation; and means for informing the network device that the TA estimation has been obtained. In some embodiments, means for determining determines the activation of the C-LTM upon obtaining of a TA value; and means for performing starts or continues the evaluation of the at least one C-LTM condition that is related to a RS used for the TA estimation.

[0258] In some embodiments, the apparatus further comprises means for performing RRC configuration processing for the at least one candidate cell. In some embodiments, RRC configuration processing for the at least one candidate cell comprises at least one of: Abstract Syntax Notation One (ASN. l) decoding of the RRC configuration for the at least one candidate cell; and validity check of the RRC configuration for the at least one candidate cell. In some embodiments, means for determining determines activation of the C-LTM upon performing the RRC configuration processing; and means for performing performs the evaluation by starting or continuing the evaluation of the C-LTM conditions for the at least one candidate cell for which the RRC configuration processing is performed.

[0259] In some embodiments, the apparatus further comprises means for switching from dual connectivity to single connectivity. In some embodiments, means for determining determines activation of the C-LTM based on determining that the terminal device switches from dual connectivity to the single connectivity; and means for performing starts evaluation of C-LTM conditions for one or more candidate cells or for cells for which the activation of the C-LTM has occurred while being in dual connectivity.

[0260] In some embodiments, the apparatus further comprises means for receiving an indication of a first timer from the network device, wherein the first timer is started or restarted by the terminal device upon TCI state activation or upon obtaining a TA estimate for triggering the terminal device to start or continue the evaluation of the at least one C-LTMcondition. In some embodiments, upon expiry of the first timer, the means for determining determines deactivation of the C-LTM; and the means for performing stops the evaluation of the at least one C-LTM condition which was started or continued when the first timer was started or restarted. In some embodiments, a time duration of the first timer is configured or specified; a common time duration is configured or specified for multiple candidate cells; or a time duration is configured separately for a candidate cell. In some embodiments, upon expiry of a second timer for considering valid TCI state activation, the means for determining determines the deactivation of the C-LTM; and the means for performing stops the evaluation of the at least one C-LTM condition based on the determined deactivation.

[0261] In some embodiments, the apparatus further comprises means for autonomously performing a TCI state activation for a candidate cell with previously activated C-LTM. In some embodiments, for beam-specific C-LTM activation, in the case that a plurality of newly activated TCI states are different from the TCI states that were previously activated, the means for performing starts or continues the evaluation of conditions for a RS associated to the plurality of newly activated TCI states and stops the evaluation of conditions for a RS associated with previously activated TCI states which are not included in the plurality of newly activated TCI states.

[0262] In some embodiments, the apparatus further comprises means for autonomously performing a TCI state activation or a TA estimation for a candidate cell which is not previously activated while Ml candidate cells are activated, wherein Ml is a maximum number of cells for which the terminal device is able to evaluate conditions simultaneously. In some embodiments, the means for determining determines deactivation of the C-LTM upon autonomously perform a TCI state activation or a TA estimation for more than Ml candidate cells; and the means for performing performs the evaluation by performing cellspecific condition evaluation for up to latest Ml candidate cells. In some embodiments, the apparatus further comprises means for autonomously performing a TCI state activation or a TA estimation for more than M4 RSs, wherein M4 is a maximum number of RSs or a maximum number of C-LTM evaluations that can be performed simultaneously. In some embodiments, the means for determining determines deactivation of the C-LTM upon autonomously performing the TCI state activation or the TA estimation for more than M4 RSs; and for beam-specific activation, the means for performing performs condition evaluation for up to M4 RSs associated with a latest TCI state activation or a latest TA estimation.

[0263] In some embodiments, the apparatus further comprises means for autonomouslyperforming a TA estimation which has an RS not associated to currently evaluated or active conditions for a candidate cell with previously activated C-LTM. In some embodiments, the means for determining determines deactivation of the C-LTM when the terminal devicebased TA estimation has the RS not associated to currently evaluated or active conditions, and the means for performing performs the evaluation by continuing the evaluation for the candidate cell with previously activated C-LTM based on a latest terminal device-based TA estimation.

[0264] In some embodiments, the means for determining determines deactivation of the C- LTM upon determining that a TA becomes invalid; and the means for performing stops evaluation of the conditions for the at least one candidate cell for which the TA becomes invalid.

[0265] In some embodiments, the means for determining determines deactivation of the C- LTM based on determining that the terminal device has not reported a beam for the at least one candidate cell for a duration starting from a last measurement repot; and the means for performing performs the evaluation by stopping the evaluation for the at least one candidate cell. In some embodiments, the measurement report is a layer 1 (LI) report or a layer 3 (L3) report.

[0266] In some embodiments, the means for determining determines deactivation of the C- LTM based on determining that the terminal device switches from single connectivity to dual connectivity; and the means for performing stops the evaluation of one or more C-LTM conditions.

[0267] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 800. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

[0268] In some embodiments, an apparatus capable of performing any of the method 900 (for example, the first network device 120) may include means for performing the respective steps of the method 900. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0269] The apparatus comprises means for transmitting, to a terminal device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam.

[0270] In some embodiments, for multiple candidate cells or per candidate cell, or formultiple candidate beams or per candidate beam, the indication of activation is used for an initial activation of the C-LTM, and the indication of deactivation is used for an initial deactivation of the C-LTM.

[0271] In some embodiments, the indication of the activation of the C-LTM comprises: a radio resource control (RRC) signaling during the LTM preparation phase from the network device for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam; or an activation trigger from the network device. In some embodiments, the indication of the deactivation of the C-LTM comprises: a radio resource control (RRC) signaling during the LTM preparation phase from the network device for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam; or a deactivation trigger from the network device.

[0272] In some embodiments, the RRC signaling during the LTM preparation phase is configured to indicate at least one of following: activation of the C-LTM in the case that there is a flag in an LTM-config information element (IE) for global activation or deactivation or in an LTM-candidate IE for per cell activation or deactivation, and deactivation of the C- LTM in the case that there is no the flag in the LTM-config IE or the LTM-candidate IE; activation and deactivation of the C-LTM with different values of the flag; activation and deactivation of the C-LTM as indicated by the flag after a cell switch; indicating the terminal device to perform an evaluation of at least one C-LTM condition based on an RRC reconfiguration or based on the trigger from the network device; or whether or not the terminal device to suspend the evaluation and wait for the trigger from the network device after an inter-centralized unit (CU) changes.

[0273] In some embodiments, at least one subsequent activation of the C-LTM is based on the activation trigger from the network device; and at least one subsequent deactivation of the C-LTM is based on the deactivation trigger from the network device.

[0274] In some embodiments, the RRC signaling during the LTM preparation phase further comprises a time duration of a first timer of activation of the C-LTM, the first timer is to be started or restarted by the terminal device at reception of message from the network device for triggering the terminal device to start or continue evaluation of at least one C-LTM condition, and a duration time of the first timer is configured by the network device or specified for multiple candidate cells or multiple candidate beams or separately configured or specified for a candidate cell or a candidate beam.

[0275] In some embodiments, the RRC signaling during the LTM preparation phase further comprises a time duration of a second timer for blocking subsequent C-LTM, and whereinthe second timer is to be started by the terminal device when a conditional cell switch is executed. In some embodiments, the activation trigger from the network device further comprises a transmission configuration indication (TCI) state activation command having an implicit indication of activation of the C-LTM or an explicit indication of activation of the C-LTM.

[0276] In some embodiments, at least one C-LTM condition for evaluation is related to a reference signal (RS) associated to an activated TCI state, or multiple conditions configured for the at least one candidate cell or the at least one candidate beam; and the RS associated to the activated TCI state comprises at least one of the following: a quasi-Co-Location (QCL) information RS of TCI state; a QCL source RS of the QCL information RS of the TCI state

[0277] In some embodiments, the activation trigger from the network device comprises a physical downlink control channel (PDCCH) order having an implicit indication of activation of the C-LTM or an explicit indication of activation of the C-LTM; and at least one C-LTM condition for evaluation is related to a reference signal (RS) indicated in the PDCCH order or related to multiple conditions configured for the at least one candidate cell or the at least one candidate beam.

[0278] In some embodiments, the activation trigger from the network device further comprises a TA information message from the network device, and at least one L-LTM condition for evaluation is related to a RS indicated in a PDCCH order to which the TA information message corresponds or multiple conditions configured for the at least one candidate cell or the at least one candidate beam.

[0279] In some embodiments, the activation trigger from the network device further comprises a C-LTM activation medium access control-control element (MAC-CE) comprising at least one of the following: cell identification to indicate activation of the C- LTM for a specific cell; indication of a beam for beam-specific condition activation; or indication instructing the terminal device to activate the C-LTM for intra-CU candidate cells or the inter-CU candidate cells.

[0280] In some embodiments, at least one C-LTM condition for evaluation is related to conditions as indicated by the C-LTM activation MAC-CE. In some embodiments, the deactivation trigger from the network device comprises a TCI state activation or deactivation command for a candidate cell with previously activated C-LTM; and the apparatus further comprises means for transmitting, to the terminal device, the TCI state activation or deactivation command for the candidate cell with previously activated C-LTM.

[0281] In some embodiments, the TCI state activation or deactivation command for thecandidate cell with previously activated C-LTM comprises candidate cell TCI state activation command for another beam, wherein for beam-specific C-LTM activation, in the case that a plurality of newly activated TCI states are different from the TCI states that were previously activated, the evaluation of conditions for a RS associated to the plurality of newly activated TCI states is started or continued by the terminal device, and the evaluation of conditions for a RS associated with previously activated TCI states which are not included in the plurality of newly activated TCI states is stopped by the terminal device.

[0282] In some embodiments, the deactivation trigger from the network device comprises a TCI state activation command, a PDCCH order, or a TA information for a candidate cell which is not previously activated while Ml candidate cells are activated, wherein Ml is a maximum number of cells for which the terminal device is able to evaluate conditions simultaneously, and the apparatus further comprises means for transmitting, to the terminal device, the TCI state activation command, the PDCCH order, or the TA information, and cellspecific condition evaluation for up to latest Ml candidate cells for which TCI state was activated, PDCCH order was received or TA information was acquired are performed by the terminal device.

[0283] In some embodiments, the deactivation trigger from the network device comprises a TCI state activation command, a PDCCH order, or a TA information for M2 RSs not associated with previously activated conditions while M3 conditions are activated, the sum of M2 and M3 is greater than M4 and M4 is a maximum number of RSs or a maximum number of C-LTM evaluations that can be performed simultaneously; and the apparatus further comprises means for transmitting, to the terminal device, the TCI state activation command, the PDCCH order, or the TA information for M2 RSs, wherein, for beam-specific activation, condition evaluation for up to M4 RSs associated with a latest TCI state activation, a latest PDCCH order or a latest TA information is performed by the terminal device.

[0284] In some embodiments, for beam-specific activation, the deactivation trigger from the network device comprises a PDCCH order or a TA information having an RS not associated to currently evaluated or active conditions for a candidate cell with previously activated C-LTM. In some embodiments, the deactivation trigger from the network device comprises a C-LTM deactivation MAC-CE comprising at least one of the following: cell identification to indicate deactivation of the C-LTM for a specific cell; indication of a beam for beam-specific condition deactivation; or indication instructing the terminal device to deactivate the C-LTM for the intra-CU candidate cells or the inter-CU candidate cells.

[0285] In some embodiments, the apparatus further comprises means for transmitting, tothe terminal device, the C-LTM deactivation MAC-CE, and evaluation of C-LTM conditions is stopped by the terminal device as indicated by the C-LTM deactivation MAC-CE.

[0286] In some embodiments the deactivation trigger from the network device comprises an RRC reconfiguration or deconfiguration message, and the apparatus further comprises means for transmitting, to the terminal device, the RRC reconfiguration or deconfiguration message, and evaluation of C-LTM conditions is stopped by the terminal device upon reception of the RRC reconfiguration or deconfiguration message.

[0287] In some embodiments, the deactivation trigger from the network device comprises a cell switch command or handover command; and the apparatus further comprises means for transmitting, to the terminal device, the cell switch command or handover command, and based on the cell switch command or handover command, evaluation of multiple C-LTM condition or evaluation of C-LTM conditions for inter-CU cells is stopped by the terminal device, and evaluation of C-LTM conditions for intra-CU cells is continued by the terminal device.

[0288] In some embodiments, the apparatus further comprises means for transmitting, to a target distributed unit (T-DU) via a centralized unit (CU), a notification of activation of the C-LTM for a first specific cell or a first specific beam in the case that evaluation of C-LTM condition for the first specific cell or the first specific beam is stated or continued by the terminal device; or transmits, to the T-DU via the CU, a notification of deactivation of the C- LTM for a second specific cell or a second specific beam in the case that evaluation of C- LTM condition for the second specific cell or the second specific beam is stopped by the terminal device.

[0289] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 900. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

[0290] In some embodiments, an apparatus capable of performing any of operations of the method 1000 (for example, the network device 120) may include means for performing the respective steps of the method 1000. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

[0291] In some embodiments, the apparatus comprises means for receiving from the terminal device, the indication that the C-LTM has been activated by the terminal device, in the case that the activation of the C-LTM is determined by the terminal device forautonomously activating at least one TCI state upon activation of the TCI state, and evaluation of at least one C-LTM condition that is related to a reference signal (RS) associated to an activated TCI state is started or continued by the terminal device based on the activation of the C-LTM.

[0292] In some embodiments, the means for receiving receives, from the terminal device, the indication that the C-LTM has been activated by the terminal device, in the case that activation of the C-LTM is determined by the terminal device upon obtaining of a TA value, and evaluation of at least one C-LTM condition that is related to a RS used for the TA estimation is started or continued by the terminal device based on the obtaining of the TA estimate.

[0293] In some embodiments, the means for receiving receives, from the terminal device, the indication that the C-LTM has been activated by the terminal device, in the case that activation of the C-LTM is determined by the terminal device upon performing a RRC configuration processing, and evaluation of C-LTM conditions for which the RRC configuration processing is started or continued by the terminal device.

[0294] In some embodiments, the means for receiving receives, from the terminal device, the indication that the C-LTM has been activated by the terminal device, in the case that activation of the C-LTM is determined by the terminal device based on determining that the terminal device switches from dual connectivity to the single connectivity, and evaluation of C-LTM conditions for one or more candidate cells or for cells for which the activation of the C-LTM has occurred while being in dual connectivity is started or continued by the terminal device.

[0295] In some embodiments, the apparatus further comprises means for transmitting, an indication of a first timer to the terminal device, wherein the first timer is started or restarted by the terminal device upon reception of message from the network device for triggering the terminal device to start or continue evaluation of at least one C-LTM condition, upon TCI state activation or upon obtaining a TA estimate; and time duration of the first timer is configured or specified; a common time duration is configured or specified for one or more candidate cells; or a time duration is configured separately for each candidate cell.

[0296] In some embodiments, the means for receiving receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device, in the case that the deactivation of the C-LTM is determined by the terminal device upon expiry of the first timer, and evaluation of at least one C-LTM condition which was started or continued when the first timer is started or restarted is stopped by the terminal device.

[0297] In some embodiments, the means for receiving receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device, in the case that the deactivation of the C-LTM is determined by the terminal device upon expiry of a second timer for considering valid TCI state activation.

[0298] In some embodiments, the means for receiving receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device for autonomously performing a TCI state activation for a candidate cell with previously activated C-LTM, in the case that for beam-specific C-LTM activation, a plurality of newly activated TCI states are different from the TCI states that were previously activated, the evaluation of conditions for a RS associated to the plurality of newly activated TCI states is started or continued by the terminal device and the evaluation of conditions for a RS associated with previously activated TCI states which are not included in the plurality of newly activated TCI states is stopped by the terminal device.

[0299] In some embodiments, the means for receiving receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device for autonomously performing a TCI state activation or a TA estimation for more than Ml candidate cells, wherein Ml is a maximum number of cells for which the terminal device is able to evaluate conditions simultaneously.

[0300] In some embodiments, the means for receiving receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device for autonomously performing autonomously perform a TCI state activation or a TA estimation for more than M4 RSs, wherein M4 is a maximum number of RSs or a maximum number of C-LTM evaluations that can be performed simultaneously.

[0301] In some embodiments, the means for receiving receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device for autonomously performing a TA estimation which has an RS not associated to currently evaluated or active conditions for a candidate cell with previously activated C-LTM.

[0302] In some embodiments, the means for receiving receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device for determining deactivation of the C-LTM upon determining that a TA becomes invalid.

[0303] In some embodiments, the means for receiving receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device in the case that deactivation of the C-LTM is determined by the terminal device based on determining that the terminal device has not reported a beam for the at least one candidate cell for a durationstarting from a last measurement report, and the measurement report is an LI report or an L3 report.

[0304] In some embodiments, the means for receiving receives, from the terminal device, the indication that the C-LTM has been deactivated by the terminal device in the case that deactivation of the C-LTM is determined by the terminal device based on determining that the terminal device switches from single connectivity to a dual connectivity.

[0305] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 1000. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

[0306] FIG. 11 is a simplified block diagram of a device 1100 that is suitable for implementing embodiments of the present disclosure. The device 1100 may be provided to implement the communication device, for example the terminal device 110, the first to third network device 120, 130, and 140 as shown in Fig. 1. As shown, the device 1100 includes one or more processors 1110, one or more memories 1120 coupled to the processor 1110, and one or more communication modules 1140 coupled to the processor 1110.

[0307] The communication module 1140 is for bidirectional communications. The communication module 1140 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements.

[0308] The processor 1110 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1100 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

[0309] The memory 1120 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a read only memory (ROM) 1124, an electrically programmable read only memory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disk (DVD), and other magnetic storage and / or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 1122 and other volatile memories that will not last in the power-down duration.

[0310] A computer program 1130 includes computer executable instructions that are executed by the associated processor 1110. The program 1130 may be stored in the ROM 1124. The processor 1110 may perform any suitable actions and processing by loading the program 1130 into the RAM 1122.

[0311] The embodiments of the present disclosure may be implemented by means of the program so that the device 1100 may perform any process of the disclosure as discussed with reference to Figs. 2A to Fig. 10. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0312] In some embodiments, the program 1130 may be tangibly contained in a computer readable medium which may be included in the device 1100 (such as in the memory 1120) or other storage devices that are accessible by the device 1100. The device 1100 may load the program 1130 from the computer readable medium to the RAM 1122 for execution. The computer readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. Fig. 12 shows an example of the computer readable medium 1200 in form of CD or DVD. The computer readable medium has the program 1130 stored thereon.

[0313] Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0314] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out processes 200Ato 1000 as described above with reference to Fig. 2Ato Fig. 10. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between programmodules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

[0315] Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0316] In the context of the present disclosure, the computer program codes or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

[0317] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD- ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0318] Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particularembodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

[0319] Although the present disclosure has been described in languages specific to structural features and / or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

WHAT IS CLAIMED IS:

1. A terminal device comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to: receive, from a network device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam; and in case of reception of the indication of the activation of C-LTM for the at least one candidate cell or for the at least one candidate beam, start or continue evaluation of at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam; or in case of reception of the indication of the deactivation of C-LTM for the at least one candidate cell or for the at least one candidate beam, stop evaluation of the at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam.

2. The terminal device of claim 1, wherein for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam, the indication of activation is used for an initial activation of the C-LTM, and the indication of deactivation is used for an initial deactivation of the C-LTM.

3. The terminal device of claim 1 or 2, wherein the indication of the activation of the C-LTM comprises: a radio resource control (RRC) signaling during the LTM preparation phase from the network device for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam; or an activation trigger from the network device.

4. The terminal device of any of claims 1 to 3, wherein the indication of the deactivation of the C-LTM comprises: a radio resource control (RRC) signaling during the LTM preparation phase from the63network device for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam; or a deactivation trigger from the network device.

5. The terminal device of claim 3 or 4, wherein the RRC signaling during the LTM preparation phase is configured to indicate at least one of following: activation of the C-LTM in the case that there is a flag in an LTM-config information element (IE) for global activation or deactivation or in an LTM-candidate IE for per cell activation or deactivation, and deactivation of the C-LTM in the case that there is no the flag in the LTM-config IE or the LTM-candidate IE; activation and deactivation of the C-LTM with different values of the flag; activation and deactivation of the C-LTM as indicated by the flag after a cell switch; indicating the terminal device to perform an evaluation of at least one C-LTM condition based on an RRC reconfiguration or based on the trigger from the network device; or whether or not the terminal device to suspend the evaluation and wait for the trigger from the network device after an inter-centralized unit (CU) changes.

6. The terminal device of any of claims 3 to 5, wherein the terminal device is caused to: start the evaluation of the at least one C-LTM condition for the at least one candidate cell or the at least one candidate beam for which the C-LTM is activated, wherein the C-LTM for the at least one candidate cell or the at least one candidate beam is at least one of the following: activated according to explicit configuration in the RRC signaling; deactivated by default until the activation trigger from the network device is received or until a terminal device-based timing advance (TA) estimation is obtained; or activated by default until a deactivation trigger from the network device is received or until cell switch is executed.

7. The terminal device of any of claims 3 to 6, wherein at least one subsequent activation of the C-LTM is performed based on the activation trigger from the network device; and wherein at least one subsequent deactivation of the C-LTM is performed based on thedeactivation trigger from the network device.

8. The terminal device of any of claims 3 to 6, wherein the RRC signaling during the LTM preparation phase further comprises a time duration of a first timer of activation of the C-LTM, wherein the first timer is configured to be started or restarted at reception of message from the network device for triggering the terminal device to start or continue the evaluation of the at least one C-LTM condition, wherein a duration time of the first timer is configured or specified for multiple candidate cells or multiple candidate beams, or separately configured or specified for a candidate cell or a candidate beam.

9. The terminal device of claim 8, wherein the terminal device is further caused to: start or restart the first timer, upon starting or continuing the evaluation of the at least one C-LTM condition; and upon expiry of the first timer, stop the evaluation of the at least one C-LTM condition which was started or continued when the first timer was started or restarted.

10. The terminal device of any of claims 3 to 9, wherein the RRC signaling during the LTM preparation phase further comprises a time duration of a second timer for blocking subsequent C-LTM, wherein the second timer is configured to be started when a conditional cell switch is executed.

11. The terminal device of claim 10, wherein the terminal device is further caused to: stop the evaluation of the at least one C-LTM condition while the second timer is running; and start the evaluation of the at least one C-LTM condition upon expiry of the second timer.

12. The terminal device of any of claims 3 to 11, wherein the activation trigger from the network device further comprises a transmission configuration indication (TCI) state activation command having an implicit indication of activation of the C-LTM or an explicit indication of activation of the C-LTM.6513. The terminal device of claim 12, wherein upon reception of the TCI state activation command, or after completion of the TCI state activation, the terminal device is caused to: start or continue the evaluation of the at least one C-LTM condition that is related to a reference signal (RS) associated to an activated TCI state; or start or continue the evaluation of multiple conditions configured for the at least one candidate cell or the at least one candidate beam.

14. The terminal device of claim 12 or 13, wherein the terminal device is further caused to: use the activated TCI state for which associated C-LTM condition is met to access the target cell.

15. The terminal device of any of claim 13 or 14, wherein the RS associated to the activated TCI state comprises at least one of the following: a quasi-Co-Location (QCL) information RS of TCI state; or a QCL source RS of the QCL information RS of the TCI state.

16. The terminal device of any of claims 3 to 15, wherein the activation trigger from the network device comprises a physical downlink control channel (PDCCH) order having an implicit indication of activation of the C-LTM or an explicit indication of activation of the C-LTM.

17. The terminal device of claim 16, wherein the terminal device is further caused to: use a transmission configuration indication (TCI) state associated with an RS index in the PDCCH order to access the target cell.

18. The terminal device of claim 16 or 17, wherein the terminal device is caused to: start or continue the evaluation of the at least one C-LTM condition, upon reception of the PDCCH order, after sending a physical random-access channel (PRACH) transmission, or after receiving a timing advance (TA) value associated with the RACH triggered by the PDCCH order, wherein the at least one C-LTM condition is related to a RS indicated in the PDCCH order or related to multiple conditions configured for the at least one candidate cell or the atleast one candidate beam.

19. The terminal device of any of claims 3 to 18, wherein the activation trigger from the network device further comprises a TA information message from the network device.

20. The terminal device of claim 19, wherein upon reception of the TA information, or upon reception of the TA information along with an explicit indication for C-LTM activation, the terminal device is caused to: start or continue the evaluation of the at least one conditions related to a RS indicated in a PDCCH order to which the TA information message corresponds; or start or continue the evaluation of multiple conditions configured for the at least one candidate cell or the at least one candidate beam.

21. The terminal device of any of claim 3 to 20, wherein the activation trigger from the network device further comprises a C-LTM activation medium access control-control element (MAC-CE) comprising at least one of the following: a cell identification to indicate activation of the C-LTM for a specific cell; an indication of a beam for beam-specific condition activation; or an indication instructing the terminal device to activate the C-LTM for intra-CU candidate cells or the inter-CU candidate cells.

22. The terminal device of claim 21, wherein the terminal device is caused to: upon reception of the C-LTM activation MAC-CE, after processing the C-LTM activation MAC-CE, or after sending an acknowledgement associated with reception of the C-LTM activation MAC-CE, start or continue the evaluation of C-LTM conditions as indicated by the C-LTM activation MAC-CE.

23. The terminal device of any of claims 4 to 22, wherein the deactivation trigger from the network device comprises a TCI state activation or deactivation command for a candidate cell with previously activated C-LTM.

24. The terminal device of any of claim 23, wherein the TCI state activation or deactivation command for the candidate cell with previously activated C-LTM comprises candidate cell TCI state activation command for another beam,67wherein the terminal device is caused to: for beam-specific C-LTM activation, in the case that a plurality of newly activated TCI states are different from the TCI states that were previously activated, start or continue the evaluation of conditions for a RS associated to the plurality of newly activated TCI states and stop the evaluation of conditions for a RS associated with previously activated TCI states which are not included in the plurality of newly activated TCI states.

25. The terminal device of any of claims 4 to 24, wherein the deactivation trigger from the network device comprises a TCI state activation command, a PDCCH order, or a TA information for a candidate cell which is not previously activated while Ml candidate cells are activated, wherein Ml is a maximum number of cells for which the terminal device is able to evaluate conditions simultaneously, wherein the terminal device is further caused to: perform cell-specific condition evaluation for up to latest Ml candidate cells for which TCI state was activated, PDCCH order was received or TA information was acquired.

26. The terminal device of any of claims 4 to 25, wherein the deactivation trigger from the network device comprises a TCI state activation command, a PDCCH order, or a TA information for M2 RSs not associated with previously activated conditions while M3 conditions are activated, wherein the sum of M2 and M3 is greater than M4 and M4 is a maximum number of RSs or a maximum number of C-LTM evaluations that can be performed simultaneously; and wherein the terminal device is further caused to: perform condition evaluation for up to M4 RSs associated with a latest TCI state activation, a latest PDCCH order or a latest TA information.

27. The terminal device of any of claims 4 to 26, wherein the deactivation trigger from the network device comprises a PDCCH order or a TA information having an RS not associated to currently evaluated or active conditions for a candidate cell with previously activated C-LTM.

28. The terminal device of any of claims 4 to 27, wherein the deactivation trigger from the network device comprises a C-LTM deactivation MAC-CE comprising at least oneof the following: a cell identification to indicate deactivation of the C-LTM for a specific cell; an indication of a beam for beam-specific condition deactivation; or an indication instructing the terminal device to deactivate the C-LTM for the intra- CU candidate cells or the inter-CU candidate cells.

29. The terminal device of claim 28, wherein the terminal device is further caused to: upon reception of the C-LTM deactivation MAC-CE, after processing the C-LTM deactivation MAC-CE, or after sending an acknowledgement associated with reception of the C-LTM deactivation MAC-CE, stop the evaluation as indicated by the C-LTM deactivation MAC-CE.

30. The terminal device of any of claims 4 to 29, wherein the deactivation trigger from the network device comprises an RRC reconfiguration or deconfiguration message, and wherein the terminal device is further caused to: stop evaluation of C-LTM conditions upon receiving the RRC reconfiguration or deconfiguration message.

31. The terminal device of any of claims 4 to 30, wherein the deactivation trigger from the network device comprises a cell switch command or handover command; and wherein the terminal device is caused to: stop evaluation of C-LTM conditions for both inter-CU cells and intra-CU cells; or stop evaluation of C-LTM conditions for inter-CU cells and continue evaluation of C-LTM conditions for intra-CU cells.

32. A network device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to: transmit, to a terminal device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam.

33. The network device of claim 32, wherein for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam, the indication of activation is used for an initial activation of the C-LTM, and the indication of deactivation is used for an initial deactivation of the C-LTM.

34. The network device of claim 32 or 33, wherein the indication of the activation of the C-LTM comprises: a radio resource control (RRC) signaling during the LTM preparation phase from the network device for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam; or an activation trigger from the network device.

35. The network device of any of claims 32 to 34, wherein the indication of the deactivation of the C-LTM comprises: a radio resource control (RRC) signaling during the LTM preparation phase from the network device for multiple candidate cells or per candidate cell, or for multiple candidate beams or per candidate beam; or a deactivation trigger from the network device.

36. The network device of claim 34 or 35, wherein the RRC signaling during the LTM preparation phase is configured to indicate at least one of following: activation of the C-LTM in the case that there is a flag in an LTM-config information element (IE) for global activation or deactivation or in an LTM-candidate IE for per cell activation or deactivation, and deactivation of the C-LTM in the case that there is no the flag in the LTM-config IE or the LTM-candidate IE; activation and deactivation of the C-LTM with different values of the flag; activation and deactivation of the C-LTM as indicated by the flag after a cell switch; indicating the terminal device to perform an evaluation of at least one C-LTM condition based on an RRC reconfiguration or based on the trigger from the network device; or whether or not the terminal device to suspend the evaluation and wait for the trigger from the network device after an inter-centralized unit (CU) changes.

37. The network device of any of claims 34 to 36, wherein at least one subsequentactivation of the C-LTM is based on the activation trigger from the network device; and at least one subsequent deactivation of the C-LTM is based on the deactivation trigger from the network device.

38. The network device of any of claims 34 to 37, wherein the RRC signaling during the LTM preparation phase further comprises a time duration of a first timer of activation of the C-LTM, wherein the first timer is to be started or restarted by the terminal device at reception of message from the network device for triggering the terminal device to start or continue evaluation of at least one C-LTM condition, and wherein a duration time of the first timer is configured by the network device or specified for multiple candidate cells or multiple candidate beams or separately configured or specified for a candidate cell or a candidate beam.

39. The network device of any of claims 34 to 38, wherein the RRC signaling during the LTM preparation phase further comprises a time duration of a second timer for blocking subsequent C-LTM, and wherein the second timer is to be started by the terminal device when a conditional cell switch is executed.

40. The network device of any of claims 34 to 38, wherein the activation trigger from the network device further comprises a transmission configuration indication (TCI) state activation command having an implicit indication of activation of the C-LTM or an explicit indication of activation of the C-LTM.

41. The network device of any of claim 40, wherein at least one C-LTM condition for evaluation is related to a reference signal (RS) associated to an activated TCI state, or multiple conditions configured for the at least one candidate cell or the at least one candidate beam; and wherein the RS associated to the activated TCI state comprises at least one of the following: a quasi-Co-Location (QCL) information RS of TCI state; a QCL source RS of the QCL information RS of the TCI state42. The network device of any of claims 34 to 41, wherein the activation trigger fromthe network device comprises a physical downlink control channel (PDCCH) order having an implicit indication of activation of the C-LTM or an explicit indication of activation of the C-LTM; and at least one C-LTM condition for evaluation is related to a reference signal (RS) indicated in the PDCCH order or related to multiple conditions configured for the at least one candidate cell or the at least one candidate beam.

43. The network device of any of claims 34 to 42, wherein the activation trigger from the network device further comprises a TA information message from the network device, and wherein at least one L-LTM condition for evaluation is related to a RS indicated in a PDCCH order to which the TA information message corresponds or multiple conditions configured for the at least one candidate cell or the at least one candidate beam.

44. The network device of any of claim 34 to 43, wherein the activation trigger from the network device further comprises a C-LTM activation medium access control-control element (MAC-CE) comprising at least one of the following: cell identification to indicate activation of the C-LTM for a specific cell; indication of a beam for beam-specific condition activation; or indication instructing the terminal device to activate the C-LTM for intra-CU candidate cells or the inter-CU candidate cells.

45. The network device of claim 44, wherein at least one C-LTM condition for evaluation is related to conditions as indicated by the C-LTM activation MAC-CE.

46. The network device of any of claims 35 to 45, wherein the deactivation trigger from the network device comprises a TCI state activation or deactivation command for a candidate cell with previously activated C-LTM; wherein the network device is further caused to: transmit, to the terminal device, the TCI state activation or deactivation command for the candidate cell with previously activated C-LTM.

47. The network device of any of claim 46, wherein the TCI state activation or deactivation command for the candidate cell with previously activated C-LTM comprisescandidate cell TCI state activation command for another beam, wherein for beam-specific C- LTM activation, in the case that a plurality of newly activated TCI states are different from the TCI states that were previously activated, the evaluation of conditions for a RS associated to the plurality of newly activated TCI states is started or continued by the terminal device, and the evaluation of conditions for a RS associated with previously activated TCI states which are not included in the plurality of newly activated TCI states is stopped by the terminal device.

48. The network device of any of claims 35 to 47, wherein the deactivation trigger from the network device comprises a TCI state activation command, a PDCCH order, or a TA information which is not previously activated while Ml candidate cells are activated, wherein Ml is a maximum number of cells for which the terminal device is able to evaluate conditions simultaneously, wherein the network device is further caused to: transmit, to the terminal device, the TCI state activation command, the PDCCH order, or the TA information, wherein cell-specific condition evaluation for up to latest Ml candidate cells for which TCI state was activated, PDCCH order was received or TA information was acquired are performed by the terminal device.

49. The network device of any of claims 35 to 48, wherein the deactivation trigger from the network device comprises a TCI state activation command, a PDCCH order, or a TA information for M2 RSs not associated with previously activated conditions while M3 conditions are activated, wherein the sum of M2 and M3 is greater than M4 and M4 is a maximum number of RSs or a maximum number of C-LTM evaluations that can be performed simultaneously; and wherein the network device is further caused to: transmit, to the terminal device, the TCI state activation command, the PDCCH order, or the TA information for M2 RSs, wherein condition evaluation for up to M4 RSs associated with a latest TCI state activation, a latest PDCCH order or a latest TA information is performed by the terminal device50. The network device of any of claims 35 to 49, wherein the deactivation trigger from the network device comprises a PDCCH order or a TA information having an RS not associated to currently evaluated or active conditions for a candidate cell with previouslyactivated C-LTM.

51. The network device of any of claims 35 to 50, wherein the deactivation trigger from the network device comprises a C-LTM deactivation MAC-CE comprising at least one of the following: cell identification to indicate deactivation of the C-LTM for a specific cell; indication of a beam for beam-specific condition deactivation; or indication instructing the terminal device to deactivate the C-LTM for the intra-CU candidate cells or the inter-CU candidate cells.

52. The network device of claim 51, wherein the network device is further caused to: transmit, to the terminal device, the C-LTM deactivation MAC-CE, wherein evaluation of C-LTM conditions is stopped by the terminal device as indicated by the C-LTM deactivation MAC-CE.

53. The network device of any of claims 35 to 52, wherein the deactivation trigger from the network device comprises an RRC reconfiguration or deconfiguration message, wherein the network device is further caused to: transmit, to the terminal device, the RRC reconfiguration or deconfiguration message, wherein evaluation of C-LTM conditions is stopped by the terminal device upon reception of the RRC reconfiguration or deconfiguration message.

54. The network device of any of claims 34 to 53, wherein the deactivation trigger from the network device comprises a cell switch command or handover command; and wherein the network device is further caused to: transmit, to the terminal device, the cell switch command or handover command, wherein based on the cell switch command or handover command, evaluation of multiple C- LTM condition or evaluation of C-LTM conditions for inter-CU cells is stopped by the terminal device, and evaluation of C-LTM conditions for intra-CU cells is continued by the terminal device.

55. The network device of any of claims 32 to 54, wherein the network device is further caused to: transmit, to a target distributed unit (T-DU) via a centralized unit (CU), a notification74of activation of the C-LTM for a first specific cell or a first specific beam in the case that evaluation of C-LTM condition for the first specific cell or the first specific beam is stated or continued by the terminal device; or transmit, to the T-DU via the CU, a notification of deactivation of the C-LTM for a second specific cell or a second specific beam in the case that evaluation of C-LTM condition for the second specific cell or the second specific beam is stopped by the terminal device.

56. A method at a terminal device comprising: receiving, from a network device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam; and in case of reception of the indication of the activation of C-LTM for the at least one candidate cell or for the at least one candidate beam, starting or continuing evaluation of at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam; or in case of reception of the indication of the deactivation of C-LTM for the at least one candidate cell or for the at least one candidate beam, stopping evaluation of the at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam.

57. A method at a network device comprising: transmitting, to a terminal device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam.

58. An apparatus comprising: means for receiving, from a network device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam; and means for in case of reception of the indication of the activation of C-LTM for the at least one candidate cell or for the at least one candidate beam, starting or continuing evaluation of at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam; or means for in case of reception of the indication of the deactivation of C-LTM for theat least one candidate cell or for the at least one candidate beam, stopping evaluation of the at least one C-LTM condition associated with the at least one candidate cell or the at least one candidate beam.

59. An apparatus comprises: means for transmitting, to a terminal device, an indication of activation or deactivation of conditional layer 1 or layer 2 triggered mobility (C-LTM) for at least one candidate cell or for at least one candidate beam.

60. A computer readable medium comprising program instructions for causing an apparatus to perform at least the method of claim 56 or 57.

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