Enhancement to conditional cell switch procedure

Abstract

There are provided apparatuses, methods, and systems for enhancements to conditional cell switch procedures. In some embodiments, one or more conditions for conditional Layer 1 / Layer 2 Triggered Mobility (LTM) (CLTM) may be satisfied. In some embodiments, a user equipment (UE) may perform downlink (DL) fine time and / or frequency synchronization with a target cell (e.g., if not performed prior to the condition being satisfied). In some embodiments, the UE may perform Abstract Syntax Notation One (ASN.1) decoding and / or validity checks (e.g., if not performed prior to the condition being satisfied and / or based on a trigger). In some embodiments, the UE may perform preamble transmission on the target cell or perform UE- based timing advance (TA) estimation for the target cell (e.g., if not performed prior to the condition being satisfied).

Description

ENHANCEMENT TO CONDITIONAL CELL SWITCH PROCEDURE TECHNICAL FIELD

[0001] Various example embodiments relate generally to enhancements to conditional cell switch procedures. BACKGROUND

[0002] Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) is a procedure in which a gNodeB (gNB) may receive L1 and / or L3 measurement report(s) from a user equipment (UE), and / or, based on the L1 or L3 measurement report(s), the gNB may change a serving cell of the UE, for example, via a cell switch command signaled via medium access control (MAC) control element (CE). The cell switch command may indicate an LTM candidate cell configuration which the gNB had previously prepared and / or provided to the UE via radio resource control (RRC) signaling. The UE may switch to the target configuration based on the cell switch command. BRIEF DESCRIPTION

[0003] According to an aspect of the invention, there is provided an apparatus, comprising at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: (i) receive one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; (ii) determine, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; (iii) select, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; (iv) perform one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; and (v) execute the CLTM cell switch to the target cell after performing the one or more preparation actions. In some embodiments, the one or more preparation actions are at least one of: (i) downlink (DL) fine time and frequency synchronization with a target cell; (ii) early Abstract Syntax Notation One (ASN.1) decoding and at least one validity check for a target cell configuration; or (iii) timing advance (TA) acquisition via at least one of: preamble transmissionto the target cell; or user-device-based TA estimation for the target cell. In some embodiments, the instructions, when executed by the at least one processor, further cause the apparatus to perform, before initiation of the CLTM cell switch execution to the target cell, at least one of the one or more preparation actions based on one or more of the preparation actions not causing interruption to scheduling of a source cell. In some embodiments, the instructions, when executed by the at least one processor, further cause the apparatus to perform at least one of the one or more preparation actions during the CLTM cell switch execution to the target cell based on one or more of the preparation actions causing an interruption to scheduling of a source cell.

[0004] According to an aspect of the invention, there is provided a method, comprising: (i) receiving one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; (ii) determining, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; (iii) selecting, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; (iv) performing one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; and (v) executing the CLTM cell switch to the target cell after performing the one or more preparation actions. In some embodiments, the one or more preparation actions are at least one of: (i) downlink (DL) fine time and frequency synchronization with a target cell; (ii) early Abstract Syntax Notation One (ASN.1) decoding and at least one validity check for a target cell configuration; or (iii) timing advance (TA) acquisition via at least one of: preamble transmission to the target cell; or user-device-based TA estimation for the target cell. In some embodiments, the method further comprises performing, before initiation of the CLTM cell switch execution to the target cell, at least one of the one or more preparation actions based on one or more of the preparation actions not causing interruption to scheduling of a source cell. In some embodiments, the method further comprises performing at least one of the one or more preparation actions during the CLTM cell switch execution to the target cell based on one or more of the preparation actions causing an interruption to scheduling of a source cell.

[0005] According to an aspect of the invention, there is provided a non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, causethe apparatus to: (i) receive one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; (ii) determine, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; (iii) select, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; (iv) perform one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; and (v) execute the CLTM cell switch to the target cell after performing the one or more preparation actions. In some embodiments, the one or more preparation actions are at least one of: (i) downlink (DL) fine time and frequency synchronization with a target cell; (ii) early Abstract Syntax Notation One (ASN.1) decoding and at least one validity check for a target cell configuration; or (iii) timing advance (TA) acquisition via at least one of: preamble transmission to the target cell; or user-device-based TA estimation for the target cell. In some embodiments, the program instructions, when executed by the apparatus, further cause the apparatus to perform, before initiation of the CLTM cell switch execution to the target cell, at least one of the one or more preparation actions based on one or more of the preparation actions not causing interruption to scheduling of a source cell. In some embodiments, the program instructions, when executed by the apparatus, further cause the apparatus to perform at least one of the one or more preparation actions during the CLTM cell switch execution to the target cell based on one or more of the preparation actions causing an interruption to scheduling of a source cell.

[0006] According to an aspect of the invention, there is provided an apparatus, comprising: (i) means for receiving one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; (ii) means for determining, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; (iii) means for selecting, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; (iv) means for performing one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; and (v) means for executing the CLTM cell switch to the target cell after performing the one or morepreparation actions. In some embodiments, the one or more preparation actions are at least one of: (i) downlink (DL) fine time and frequency synchronization with a target cell; (ii) early Abstract Syntax Notation One (ASN.1) decoding and at least one validity check for a target cell configuration; or (iii) timing advance (TA) acquisition via at least one of: preamble transmission to the target cell; or user-device-based TA estimation for the target cell. In some embodiments, the apparatus further comprises means for performing, before initiation of the CLTM cell switch execution to the target cell, at least one of the one or more preparation actions based on one or more of the preparation actions not causing interruption to scheduling of a source cell. In some embodiments, the apparatus further comprises means for performing at least one of the one or more preparation actions during the CLTM cell switch execution to the target cell based on one or more of the preparation actions causing an interruption to scheduling of a source cell.

[0007] According to an aspect of the invention, there is provided a computer system, comprising: one or more processors; at least one data storage; and one or more computer program instructions to be executed by the one or more processors in association with the at least one data storage for carrying out: (i) receiving one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; (ii) determining, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; (iii) selecting, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; (iv) performing one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; and (v) executing the CLTM cell switch to the target cell after performing the one or more preparation actions. In some embodiments, the one or more preparation actions are at least one of: (i) downlink (DL) fine time and frequency synchronization with a target cell; (ii) early Abstract Syntax Notation One (ASN.1) decoding and at least one validity check for a target cell configuration; or (iii) timing advance (TA) acquisition via at least one of: preamble transmission to the target cell; or user-device-based TA estimation for the target cell. In some embodiments, the computer program instructions to be executed by the one or more processors in association with the at least one data storage are configured for carrying out performing, before initiation of the CLTM cell switch execution to the target cell, at least one of the one or more preparation actions based onone or more of the preparation actions not causing interruption to scheduling of a source cell. In some embodiments, the computer program instructions to be executed by the one or more processors in association with the at least one data storage are configured for carrying out performing at least one of the one or more preparation actions during the CLTM cell switch execution to the target cell based on one or more of the preparation actions causing an interruption to scheduling of a source cell. LIST OF THE DRAWINGS

[0008] In the following, the invention will be described in greater detail with reference to the embodiments and the accompanying drawings, in which:

[0009] Fig.1 shows an example of a communication network to which examples disclosed herein may be applied;

[0010] Fig.2 shows a signaling diagram illustrating an example of lower layer triggered mobility;

[0011] Fig.3 shows an example of CLTM interruption;

[0012] Fig.4 shows an example of CLTM interruption;

[0013] Fig.5 shows an example of a method;

[0014] Fig.6 shows an example of a signaling flow diagram; and

[0015] Fig.7 shows an example of an apparatus. DESCRIPTION OF EMBODIMENTS

[0016] The following embodiments are exemplary. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Further, when a particular feature, structure, or characteristic is described in connection of an embodiment, it is within the knowledge of one skilled in the art to apply such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. It shall be understood that although the terms “first”, “second”, and / or the like 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.

[0017] For the purposes of the present disclosure, the phrases “at least one of A or B”, “at least one of A and B”, and “A and / or B” mean (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and / or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0018] Embodiments described may be implemented in a communication network, such as any of the following radio access technologies (RATs): Worldwide Interoperability for Micro- wave Access (WiMAX), Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, and enhanced LTE (eLTE), 5G (also called NR), or any future RAT such as 6G. Moreover, communications within the communication network may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), and / or Discrete Fourier Transform spread OFDM (DFT-s-OFDM).

[0019] As used herein, the term “network device” or “network node” refers to a node in a communication network via which user equipment may access the network and / or which is capable of controlling radio communication and managing radio resources within a cell. The network node or network device may be referred to as a base station (BS), an access point (AP), or an access node. The network device may be, depending on the applied technology, for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio head (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node, a non- terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, or an aircraft network device.

[0020] Moreover, in connection of split radio access network (RAN), the network device may refer to a centralized unit (CU) or a base station and / or a distributed unit (DU) of a base station. An interface between CU and DU may be referred to as an F1 interface in NR. In thesplit RAN architecture, node operations may be carried out, at least partly, in the central / centralized unit, CU (e.g., server, host, or node) operationally coupled to the DU, (e.g., a radio head / node). One CU may control one or more DUs, acting at least as transmit / receive (Tx / Rx) nodes. In some embodiments, the DUs may comprise, for example, a radio link control (RLC), medium access control (MAC) layer and a physical (PHY) layer, whereas the CU may comprise the layers above the RLC layer, such as a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) and an internet protocol (IP) layers. Other functional splits are also possible. In practice, any processing task may be performed in either the CU or the DU and the boundary where the responsibility is shifted between the CU and the DU may depend on the applied implementation.

[0021] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example, a terminal device may be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), or a Mobile Station (MS). The terminal device may include 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 computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle- mounted wireless terminal devices, USB dongles, an Internet of Things (IoT) 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 context), a consumer electronics device, a device operating on commercial and / or industrial networks, and / or the like.

[0022] A term “resource”, as used herein, may refer to radio resources in time domain, in frequency domain, in space domain, and / or in code domain. Some examples of resources include, for example, physical resource block (PRB), a radio frame, a subframe, a time slot, a sub-band, a frequency region, a sub-carrier, a beam, and / or the like. The term “transmission” and / or “reception” may refer to wirelessly transmitting and / or receiving via a wireless propagation channel on radio resources.

[0023] Fig.1 illustrates an example of a communication network to which examples disclosed herein may be applied. The communication network or a cellular communicationnetwork may comprise a network node 110 providing one or more cells, such as cell 100, and a network node 112 providing one or more other cells, such as cell 102. Each cell may be, for example, a macro cell, a micro cell, a femto cell, or a pico cell, for example. The cell may define a coverage area or a service area of the corresponding access node.

[0024] The network node 110 may provide a user equipment (UE) 120 (one or more UEs) with wireless access to the communication network. The wireless access may comprise downlink (DL) communication from the network node to the UE 120 and uplink (UL) communication from the UE 120 to the network node. Examples of uplink channels comprise physical uplink control channel (PUCCH) for transmitting control information and physical uplink shared channel (PUSCH) for transmitting data towards the network. Examples of downlink channels comprise physical downlink control channel (PDCCH) for transmitting control information and physical downlink shared channel (PDSCH) for transmitting data towards the user equipment.

[0025] There may be a plurality of UEs 120, 122, in the system. Each of them may be served by the same of by different network nodes 110, 112. UE may be configured with dual connectivity (DC), wherein the UE, for example, UE 120, may be connected to multiple network nodes 110, 112. The UEs 120, 122, may communicate with each other, in case device-to-device (D2D) communication interface is established between them via a so-called sidelink (SL). Such D2D communications may be referred to as machine-to-machine, peer-to-peer (P2P) communications, or vehicle-to-vehicle (V2V), for example.

[0026] In the case of multiple network nodes in the communication network, the network nodes may be connected to each other via an interface. LTE specifications call such an interface an X2 interface. An interface between an LTE node and a 5G node, or between two 5G nodes, may be called an Xn interface.

[0027] The network nodes 110 and 112 may be further connected via another interface to a core network 116 of the communication network. The LTE specifications specify the core network as an evolved packet core (EPC), and the core network may comprise, for example, a mobility management entity (MME) and a gateway node. The MME may handle mobility of terminal devices in a tracking area encompassing a plurality of cells and handle signaling connections between the terminal devices and the core network. The gateway node may handle data routing in the core network and to / from the terminal devices. The 5G specifications specify the core network as a 5G core (5GC). The 5G core may comprise, for example, an access andmobility management function (AMF) and a use plane function / gateway (UPF) and other functions. The AMF may handle termination of non-access stratum (NAS) signaling, NAS ciphering and integrity protection, registration management, connection management, mobility management, access authentication and authorization, security context management, and / or the like. The UPF node may support packet routing and forwarding, packet inspection, and quality of service (QoS) handling, for example.

[0028] In 3GPP Rel-18, a new mobility mechanism was introduced, namely lower layer- triggered mobility (LTM), which aims to reduce interruption time during handover.

[0029] The overall procedure for LTM is illustrated in the signaling diagram of Fig.2, with reference to the network components schematically illustrated in Fig.1. Fig.2 is taken from Figure 9.2.3.5.2-1 of TS38.300v18. As described in TS38.300v18, 9.2.3.5.2, the procedure for LTM is as follows:

[0030] In Step 1 of Fig.2, the UE (e.g., the UE 120) sends a MeasurementReport message to the gNB 110, which provides access to the source cell 100. The gNB 110 decides to configure LTM and initiates LTM preparation.

[0031] In Step 2 of Fig.2, the gNB 110 transmits an RRCReconfiguration message to the UE 120 including the LTM candidate configurations.

[0032] In Step 3 of Fig.2 the UE 120 stores the LTM candidate configurations and transmits an RRCReconfigurationComplete message to the gNB 110.

[0033] In Step 4a of Fig.2, the UE 120 performs DL synchronization with the candidate cell(s) 102 before receiving the cell switch command.

[0034] In Step 4b of Fig.2, when the UE-based TA measurement is configured, the UE 120 acquires the TA value(s) of the candidate cell(s) 102 by measurement. The UE 120 performs early TA acquisition with the candidate cell(s) 102 as requested by the network before receiving the cell switch command as specified in clause 9.2.6. This is done via CFRA triggered by a PDCCH order from the source cell 100, following which the UE 120 sends preamble towards the indicated candidate cell 102. In order to minimize the data interruption of the source cell 100 due to CFRA towards the candidate cell(s) 102, the UE 120 does not receive a random access response from the network for the purpose of TA value acquisition and the TA value of the candidate cell 102 is instead indicated in the cell switch command. The UE 120 does notmaintain the TA timer for the candidate cell 102 and relies on network implementation to guarantee the TA validity.

[0035] In Step 5 of Fig.2, the UE 120 performs L1 measurements on the configured candidate cell(s) 102 and transmits L1 measurement reports to the source gNB 110.

[0036] In Step 6 of Fig.2, the gNB 110 decides to execute a cell switch from the source cell 100 to the candidate or target cell 102 and transmits a MAC CE triggering cell switch by including the candidate configuration index of the target cell 102. The UE 120 then switches to the target cell 102 and applies the configuration indicated by candidate configuration index.

[0037] In Step 7 of Fig.2 the UE 120 performs the random access procedure towards the target cell 102, if the UE 120 does not have a valid TA of the target cell 102 as specified in clause 6.1.3.xy of TS 38.321[6].

[0038] In Step 8 of Fig.2, the UE 120 completes the LTM cell switch procedure by sending RRCReconfigurationComplete message to the gNB 112 providing access to the target cell 102.

[0039] If the UE 120 has performed a RA procedure in Step 7 of Fig.2, then the UE 120 considers that LTM cell switch execution is successfully completed when the random access procedure is successfully completed.

[0040] For RACH-less LTM, the UE 120 considers that the LTM cell switch execution is successfully completed when the UE 120 determines that the network has successfully received its first UL data.

[0041] As seen above, in LTM, early TA acquisition (e.g., TA acquisition before handover / cell switch) can be performed in the following ways. Firstly, the network can order the UE 120 to perform random access (RA) preamble transmission to a candidate cell 102. The candidate cell 102 uses the received RA preamble to estimate the TA and provides the TA estimate to the source cell 100. When the source cell 100 decides to trigger the cell switch, it provides the estimated TA value along with the cell switch command. Secondly, during LTM preparation, the network can configure the UE 120 to perform UE-based TA measurements. UE- based TA measurements may be performed based on the TA of the serving cell 100 and the measured time difference between the candidate cell 102 and the serving cell 100. After being configured, the UE 120 is assumed to obtain a TA measurement before a cell switch command is issued by the gNB 110 providing access to the source cell 100.

[0042] Another purpose served by random access is that the target gNB 112 is notified about the presence of the UE 120 and resources for the UE’s subsequent transmissions are provided to the UE 120. Hence, when RACH-less LTM cell switch is performed, a mechanism is required to support the initial transmission of the UE 120 to the target cell 102. A mechanism that supports this purpose is the provisioning of configured grants, which consist of sets of resources in the candidate / target cell that the UE 120 may use if / when it performs its initial transmission after handover / cell switch to the target cell 102. An alternative to this mechanism is to provide an access notification from the source cell 100 to the target cell 102, so that the target cell 102 can then provide a dynamic grant to the UE 120 for the target cell 102.

[0043] A similar RACH-less approach has also been proposed for baseline and conditional handover (BHO / CHO) as well to facilitate fast cell switch.

[0044] In some examples, shortening interruption times via LTM may be relied upon in scenarios including CLTM. In at least some technologies, a UE may not have performed DL synchronization, UL synchronization, and / or candidate cell pre-processing for a candidate cell at a time when a condition for CLTM is satisfied. This may be due to the UE not having performed such actions prior to the condition being satisfied and / or due to the actions performed by the UE no longer applying to a given scenario (e.g., the UE may have stopped tracking DL timing of an activated transmission configuration indicator (TCI) state after a certain time duration).

[0045] Cell switch delay for CLTM may be defined, for example, as: ^^^^^^^^^^^^^^^^^^^^ = ^^^^^^^^^^^^^^^^ +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + ^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + ^^^^^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + ^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^ + ^^^^^^^^^^^^−^^^^^^^^^^^^^^^^ + ^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +processing at the time of receiving the CLTM configuration; (iii) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^is an uncertainty time from the time of receiving the CLTM configuration until the condition for CLTM is satisfied; (iv) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^is the time that is allowed for the UE to determine that the condition for CLTM is satisfied, and / or ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^can be defined as one L1 and / or L3 measurement period; (v) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^is the time for ASN.1 decoding and validity check (e.g., ^^^^^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^may have a value of 10 ms), and / or ^^^^^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^may have a value of zero, for example, if the UE has performed early ASN.1 decoding and / or validity check prior to the cell switch; (vi) ^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^is the time for DL synchronization, which may be defined as time until the first synchronization signal block (SSB) occurs after ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^; (vii) ^^^^^^^^^^^^−^^^^^^^^^^^^^^^^is the time for RS (SSB)processing, and wherein if the cell switch comprises DL synchronization, ^^^^^^^^^^^^−^^^^^^^^^^^^^^^^ > 0 and / or ifthe UE has DL synchronization at the time of cell switch, ^^^^^^^^^^^^−^^^^^^^^^^^^^^^^ = 0 and ^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^ = 0; (viii)^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^is the time for UE processing (e.g., ranging from approximately 10 ms to approximately 40 ms, depending on UE capability); and (ix) ^^^^^^^^^^^^^^^^−^^^^^^^^is the uncertainty until RACH preamble transmission (RACH-based LTM) or until first UL transmission (RACH-less LTM).

[0046] CLTM interruption in at least some technologies may be defined, for example, as: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ = ^^^^^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + ^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^ + ^^^^ ^^^^^^^^−^^^^^^^^^^^^^^^^ + ^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + ^^^^^^^^^^^^^^^^−^^^^^^^^, wheremay to

[0047] At least one problem with the above-mentioned methods is that there may be little to no savings in LTM interruption durations and / or CLTM performance may cause interruption delays which may last as long as CHO interruptions.

[0048] To at least partially tackle this problem, there are proposed solutions for enhancements to conditional cell switch procedure(s). In some embodiments, CLTM interruption may be reduced to ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ = ^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + ^^^^^^^^^^^^^^^^−^^^^^^^^, where ^^^^^^^^^^^^^^^^−^^^^^^^^ is the time until firstUL transmission (e.g., regardless of whetherperformed prior to the CLTM condition being satisfied). In some embodiments, such CLTM interruption reduction may be implemented by defining the procedure of cell switch execution such that the UE executes the cell switch, for example, after the UE has performed at least one (e.g., or all) preparation step.

[0049] Referring now to Fig.3 and Fig.4, examples of CLTM interruptions are described. In some embodiments, once the condition for CLTM is satisfied, the UE may make a cell switch decision to the candidate cell in question. In some embodiments, the UE may not immediately begin cell switch execution (e.g., CLTM interruption), which means that the UE may maintain the connection to the source cell and / or be scheduled on the source cell. In some embodiments, the UE may maintain its connection to the source cell, for example, until it has performed the following actions: (1) DL synchronization with the target cell (e.g., if not performed prior to the CLTM condition being satisfied); (2) early ASN.1 decoding and validity check (e.g., if not performed prior to the CLTM condition being satisfied based on a trigger); and (3) RACHpreamble transmission on the target cell and / or UE-based TA estimation for the target cell (e.g., if not performed prior to the CLTM condition being satisfied). In some embodiments, actions (1) and (2) may be performed in parallel (e.g., simultaneously, contemporaneously, etc.), and thus the delay caused by actions (1) and (2) may be defined as max (^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^+ ^^^^^^^^^^^^−^^^^^^^^^^^^^^^^,^^^^^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^). Additionally or alternatively, actions (1) and (2) may be performed sequentially, and thus the delay caused by actions (1) and (2) may be defined as^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^ + ^^^^^^^^^^^^−^^^^^^^^^^^^^^^^ + ^^^^^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^. In some embodiments, action (3) may beconditional, for example, depending on UE capability to cause or not cause interruption during the RACH transmission and / or UE-based TA estimation. In such cases, the following options may be implemented: (A) the UE performs (e.g., always performs) TA acquisition before cell switch execution, independent of whether interruption is caused by the TA acquisition procedure; and (B) the UE performs TA acquisition before cell switch if (e.g., only if) the UE can perform the TA acquisition procedure without causing interruption to the source cell (e.g., otherwise, the UE may perform a RACH-based cell switch wherein TA acquisition is included in the interruption).

[0050] Using approaches such as described above with respect to Fig.3 and Fig.4, theCLTM delay may be defined, for example, as follows: (i) ^^^^^^^^^^^^^^^^^^^^ = ^^^^^^^^^^^^^^^^ + ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + ^^^^^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + ^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^ + ^^^^^^^^^^^^−^^^^^^^^^^^^^^^^ + ^^^^^^^^^^^^^^^^−^^^^^^^^−^^^^^^^^ + ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^; and / or (ii)^^^^^^^^^^^^−^^^^^^^^^^^^^^^^ ,^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^� + ^^^^^^^^^^^^^^^^−^^^^^^^^−^^^^^^^^ + ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^, where: ^^^^^^^^^^^^^^^^−^^^^^^^^−^^^^^^^^ is the uncertaintyuntil the UE has performed early TA acquisition through preamble transmission and / or UE-based TA estimation. ^^^^^^^^^^^^^^^^−^^^^^^^^−^^^^^^^^may have a value of zero, for example, if valued TA is already available at the time of the CLTM condition being satisfied. In some embodiments,^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ = ^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + ^^^^^^^^^^^^^^^^−^^^^^^^^−^^^^^^^^, where ^^^^^^^^^^^^^^^^−^^^^^^^^−^^^^^^^^ is the uncertainty until a firstUL transmission.

[0051] Fig.3 shows an example of CLTM interruption. In the example of Fig.3, a CLTM delay 300 is shown. The CLTM delay 300 may arise due to LTM RRC configuration to preamble transmission, for example, in the case where no LTM preparation steps (e.g., DL synchronization, UL synchronization, early ASN.1 decoding, and / or the like) have been performed. The interruption segment may indicate the time from when the CLTM condition issatisfied until preamble transmission. Various embodiments described herein provide for reducing the interruption by delaying CLTM execution via implementing actions (1), (2), and / or (3), as described above. In some embodiments, the UE may first perform (e.g., via network configure procedures) ASN.1 decoding and validity check (^^^^^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^), DLsynchronization (^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^ + ^^^^^^^^^^^^=^^^^^^^^^^^^^^^^), and / or UL synchronization (^^^^^^^^^^^^^^^^−^^^^^^^^−^^^^^^^^); then, the UEmay perform CLTM execution.

[0052] Fig.4 shows an example of CLTM interruption. In the example of Fig.4, a CLTM delay 400 is shown. In the example of Fig.4, all three of the following actions may be performed prior to CLTM execution: ASN.1 decoding and validity check (^^^^^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^), DLsynchronization (^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^ + ^^^^^^^^^^^^=^^^^^^^^^^^^^^^^), and / or UL synchronization (^^^^^^^^^^^^^^^^−^^^^^^^^−^^^^^^^^). In someembodiments, delaying CLTM execution may be performed by performing one or more of the following actions: ASN.1 decoding and validity check (^^^^^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^), DL synchronization(^^^^^^^^^^^^^^^^^^^^^^^^−^^^^^^^^ + ^^^^^^^^^^^^=^^^^^^^^^^^^^^^^), and / or UL synchronization (^^^^^^^^^^^^^^^^−^^^^^^^^−^^^^^^^^).

[0053] Fig.5 shows an example of a method 500. The method may be computer- implemented. The method may be performed by a UE. As shown in block 510, the method 500 may comprise receiving one or more configurations including at least one candidate cell for Layer1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch. As shown in block 520, the method 500 may comprise determining, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells. As shown in block 530, the method 500 may comprise selecting, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch. As shown in block 540, the method 500 may comprise performing one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell. As shown in block 550, the method 500 may comprise executing the CLTM cell switch to the target cell after performing the one or more preparation actions.

[0054] Fig.6 shows an example of a signaling flow diagram. The signaling flow diagram of Fig.6 includes a UE 602, a source transmission and reception point (sTRP) 604, and a target transmission and reception point (tTRP) 606. At step 610, the UE may transmit an L3 measurement report to the sTRP 604 (e.g., via RRC). At step 612, the sTRP 604 may transmit aCLTM candidate cell configuration, wherein the configuration may comprise at least one condition for CLTM for the candidate cell tTRP 606 (e.g., a condition TCI-1 for the tTRP 606). At step 614, the UE may measure the candidate cell(s) (e.g., tTRP 606) and / or evaluates whether the condition is satisfied. In some embodiments, condition evaluation may start at other points in time. At step 616, the UE may perform DL synchronization to the tTRP 606 based on early TCI state activation, for example, if configured by the network. At step 618, the UE may perform UL synchronization via an early TA acquisition procedure to the tTRP 606, for example, if configured by the network. At step 620, the network may determine and / or evaluate that the condition for CLTM has been satisfied. At step 622, based on evaluating the condition (e.g., after ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^), the UE may determine that the condition for CLTM for the tTRP 606 has been satisfied. Based on this determination, the UE may make a cell switch decision. In some embodiments, the UE may maintain the connection with the source cell sTRP 604 while starting LTM preparation steps as described in steps 624, 626, and / or 628. In some embodiments, the UE may immediately perform execution of the cell switch and / or interruption. At step 624, the UE may perform DL synchronization, for example, if not previously performed (e.g., or if invalid). At step 626, the UE may perform ASN.1 decoding and / or validity check, for example, if not previously performed. In some embodiments, step 624 and step 628 may either be performed sequentially or in parallel (e.g., simultaneously, contemporaneously, etc.). At step 628, the UE may perform TA acquisition, for example, if not previously performed. In some embodiments, the TA acquisition may be performed via preamble transmission and / or UE-based TA estimation, for example, depending on network configuration. In some embodiments, step 628 may be optional, for example, as described in the following cases: (A) the UE may perform (e.g., always perform) TA acquisition before cell switch execution independent of whether performing the TA acquisition causes interruption; and / or (B) the UE may perform TA acquisition before cell switch execution, for example, if (e.g., only if) the UE can perform the TA acquisition without causing interruption to the source cell sTRP 604 (otherwise, the UE may perform RACH-based cell switch, wherein TA acquisition is part of the interruption). At step 630, the UE may start cell switch execution and / or the interruption may begin. In some embodiments, cell switch may be RACH-less or RACH-based, for example, depending on step 628. In some embodiments, the interruption may comprise UE processing time (^^^^^^^^^^^^^^^^−^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^), and / or the uncertainty in the RACH preamble and / or first UL transmission (^^^^^^^^^^^^^^^^−^^^^^^^^−^^^^^^^^).

[0055] Fig.7 shows, by way of example, a block diagram of an apparatus 10. The apparatus 10 comprises, for example, at least one processor 12 and at least one memory 14 storing instructions 15 that, when executed by the at least one processor 12, cause the apparatus 10 at least to perform the method or methods as disclosed herein, and any of the embodiments thereof. In an example, the at least one memory 14 and instructions 15 (e.g., a computer program, code, software, and / or the like) are configured, with the at least one processor 12, to cause the apparatus 10 to perform the method or methods as disclosed herein, and any of the embodiments thereof.

[0056] A processor 12 may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with example embodiments described herein. 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 user equipment, 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. This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0057] The memory 14 may be implemented using any suitable data storage technology. The memory may comprise a database for storing data. The memory 14 may be at least in part external to apparatus 10 but accessible to apparatus 10.

[0058] The instructions 15 may be comprised in a computer-readable medium or a non- transitory computer readable medium. A term “non-transitory”, as used herein, is a limitation of the medium itself (e.g., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., random access memory (RAM) vs. read only memory (ROM)).

[0059] For example, the apparatus 10 is a terminal device, such as the UE of Fig.7. As another example, the apparatus is comprised in such a terminal device, for example, as a chipset configured to control the terminal device. The apparatus 10 may be caused or configured to perform at least the method of Fig.5 and / or any one or more of the embodiments described.

[0060] As another example, the apparatus 10 is a network node, for example, the network node of Fig.6. In another embodiment, the apparatus is comprised in such a network node, for example, as a chipset configured to control the network node. The apparatus 10 may be caused or configured to perform at least the method of Fig.5 and / or any one or more of the embodiments described herein.

[0061] The apparatus may comprise one or more entities of any protocol layers, such as a MAC entity, an RRC entity, an RLC entity, a PDCP entity, a PHY entity, and / or the like. In some embodiments, the entity is configured to perform at least the method of Fig.5 or Fig.6, and / or any one or more of the embodiments described.

[0062] The apparatus 10 comprises a radio interface 16. The radio interface 16 may provide the apparatus 10 with communication capabilities. The radio interface 16 may comprise a receiver configured to receive information in accordance with at least one cellular or non-cellular standard. The radio interface 16 may comprise a transmitter configured to transmit information in accordance with at least one cellular or non-cellular standard. The receiver may comprise more than one receiver. The transmitter may comprise more than one transmitter. The radio interface 16 may comprise a transceiver configured to receive and transmit information in accordance with at least one cellular or non-cellular standard. The transceiver may comprise more than one transceiver.

[0063] The apparatus 10 may comprise a user interface 18 comprising, for example, at least one of a keypad, a microphone, a touch display, a display, a speaker, and / or the like. The user interface 18 may be used to control the apparatus by a user. The user interface 18 may be external to the apparatus 10. For example, the apparatus 10 may be connected to another device,such as a computer, either via wireless or wired connection, and the apparatus 10 is controlled by the user via the computer.

[0064] In an embodiment, at least some of the processes described herein may be carried out by an apparatus comprising means for carrying out at least some of the described processes. Means for performing method steps as disclosed herein may include software and / or hardware components of the apparatus 10. For example, the at least one processor 12, the memory 14, and the instructions 15 (e.g., computer program code) form means for carrying out the method or methods as disclosed herein, and any of the embodiments thereof. As used herein, the term “means” is to be construed in singular form, i.e., referring to a single element, or in plural form, i.e., referring to a combination of single elements. Therefore, terminology “means for [performing A, B, C]” is to be interpreted to cover an apparatus in which there is only one means for performing A, B, and C, or where there are separate means for performing A, B, and C, or partially or fully overlapping means for performing A, B, C. Further, terminology “means for performing A, means for performing B, means for performing C” is to be interpreted to cover an apparatus in which there is only one means for performing A, B, and C, or where there are separate means for performing A, B, and C, or partially or fully overlapping means for performing A, B, C.

[0065] Following is a list of some aspects of the invention.

[0066] According to a first aspect, there is provided a method, comprising: (i) receiving one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; (ii) determining, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; (iii) selecting, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; (iv) performing one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; and (v) executing the CLTM cell switch to the target cell after performing the one or more preparation actions. Various embodiments of the first aspect may comprise at least one feature from the following bulleted list: • receiving one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one ormore configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; • determining, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; • selecting, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; • performing one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; • executing the CLTM cell switch to the target cell after performing the one or more preparation actions; • performing, before initiation of the CLTM cell switch execution to the target cell, at least one of the one or more preparation actions based on one or more of the preparation actions not causing interruption to scheduling of a source cell; and / or • performing at least one of the one or more preparation actions during the CLTM cell switch execution to the target cell based on one or more of the preparation actions causing an interruption to scheduling of a source cell.

[0067] According to a second aspect, there is provided an apparatus, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: (i) receive one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; (ii) determine, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; (iii) select, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; (iv) perform one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; and (v) execute the CLTM cell switch to the target cell after performing the one or more preparation actions. Various embodiments of the second aspect may comprise at least one feature from the bulleted list under the first aspect.

[0068] According to a third aspect, there is provided a non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to carry out the method according to the first aspect.

[0069] According to a fourth aspect, there is provided an apparatus, comprising means for performing the method according to the first aspect, and / or means configured to cause the apparatus to perform the method according to the first aspect.

[0070] According to a fifth aspect, there is provided a computer system, comprising: one or more processors; at least one data storage; and one or more computer program instructions to be executed by the one or more processors in association with the at least one data storage for carrying out: (i) receiving one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; (ii) determining, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; (iii) selecting, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; (iv) performing one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; and (v) executing the CLTM cell switch to the target cell after performing the one or more preparation actions. Various embodiments of the fifth aspect may comprise at least one feature from the bulleted list under the first aspect.

[0071] Even though the invention has been described above with reference to an example according to the accompanying drawings, it is clear that the invention is not restricted thereto but can be modified in several ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. Further, it is clear to a person skilled in the art that the described embodiments may, but are not required to, be combined with other embodiments in various ways.

Claims

CLAIMS:

1. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; determine, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; select, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; perform one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; and execute the CLTM cell switch to the target cell after performing the one or more preparation actions.

2. The apparatus of claim 1, wherein the one or more preparation actions are at least one of: downlink (DL) fine time and frequency synchronization with a target cell; early Abstract Syntax Notation One (ASN.1) decoding and at least one validity check for a target cell configuration; or timing advance (TA) acquisition via at least one of: preamble transmission to the target cell; or user-device-based TA estimation for the target cell.

3. The apparatus of claim 2, wherein the instructions, when executed by the at least one processor, further cause the apparatus to: perform, before initiation of the CLTM cell switch execution to the target cell, at least one of the one or more preparation actions based on one or more of the preparation actions notcausing interruption to scheduling of a source cell.

4. The apparatus of claim 2, wherein the instructions, when executed by the at least one processor, further cause the apparatus to: perform at least one of the one or more preparation actions during the CLTM cell switch execution to the target cell based on one or more of the preparation actions causing an interruption to scheduling of a source cell.

5. A method comprising: receiving one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; determining, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; selecting, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; performing one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; and executing the CLTM cell switch to the target cell after performing the one or more preparation actions.

6. The method of claim 5, wherein the one or more preparation actions are at least one of: downlink (DL) fine time and frequency synchronization with a target cell; early Abstract Syntax Notation One (ASN.1) decoding and at least one validity check for a target cell configuration; or timing advance (TA) acquisition via at least one of: preamble transmission to the target cell; or user-device-based TA estimation for the target cell.

7. The method of claim 6, further comprising:performing, before initiation of the CLTM cell switch execution to the target cell, at least one of the one or more preparation actions based on one or more of the preparation actions not causing interruption to scheduling of a source cell.

8. The method of claim 6, further comprising: performing at least one of the one or more preparation actions during the CLTM cell switch execution to the target cell based on one or more of the preparation actions causing an interruption to scheduling of a source cell.

9. A non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to: receive one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; determine, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; select, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; perform one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; and execute the CLTM cell switch to the target cell after performing the one or more preparation actions.

10. The non-transitory computer readable medium of claim 9, wherein the one or more preparation actions are at least one of: downlink (DL) fine time and frequency synchronization with a target cell; early Abstract Syntax Notation One (ASN.1) decoding and at least one validity check for a target cell configuration; or timing advance (TA) acquisition via at least one of: preamble transmission to the target cell; or user-device-based TA estimation for the target cell.

11. The non-transitory computer readable medium of claim 10, wherein the program instructions, when executed by the apparatus, further cause the apparatus to: perform, before initiation of the CLTM cell switch execution to the target cell, at least one of the one or more preparation actions based on one or more of the preparation actions not causing interruption to scheduling of a source cell.

12. The non-transitory computer readable medium of claim 10, wherein the program instructions, when executed by the apparatus, further cause the apparatus to: perform at least one of the one or more preparation actions during the CLTM cell switch execution to the target cell based on one or more of the preparation actions causing an interruption to scheduling of a source cell.

13. An apparatus comprising: means for receiving one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; means for determining, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; means for selecting, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; means for performing one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; and means for executing the CLTM cell switch to the target cell after performing the one or more preparation actions.

14. The apparatus of claim 13, wherein the one or more preparation actions are at least one of: downlink (DL) fine time and frequency synchronization with a target cell; early Abstract Syntax Notation One (ASN.1) decoding and at least one validity check fora target cell configuration; or timing advance (TA) acquisition via at least one of: preamble transmission to the target cell; or user-device-based TA estimation for the target cell.

15. The apparatus of claim 14, further comprising: means for performing, before initiation of the CLTM cell switch execution to the target cell, at least one of the one or more preparation actions based on one or more of the preparation actions not causing interruption to scheduling of a source cell.

16. The apparatus of claim 14, further comprising: means for performing at least one of the one or more preparation actions during the CLTM cell switch execution to the target cell based on one or more of the preparation actions causing an interruption to scheduling of a source cell.

17. A computer system comprising: one or more processors; at least one data storage; and one or more computer program instructions to be executed by the one or more processors in association with the at least one data storage for carrying out: receiving one or more configurations including at least one candidate cell for Layer 1 / Layer 2 Triggered Mobility (LTM), wherein at least one of the one or more configurations of at least one candidate cell include at least one condition for conditional LTM (CLTM) cell switch; determining, based on the one or more configurations, that a condition for CLTM cell switch is satisfied for at least one of the configured candidate cells; selecting, based on the determination of the condition for CLTM being satisfied, a candidate cell as a target cell for CLTM cell switch; performing one or more cell switch preparation actions before initiating execution of the CLTM cell switch to the target cell; and executing the CLTM cell switch to the target cell after performing the one ormore preparation actions.

18. The apparatus of claim 17, wherein the one or more preparation actions are at least one of: downlink (DL) fine time and frequency synchronization with a target cell; early Abstract Syntax Notation One (ASN.1) decoding and at least one validity check for a target cell configuration; or timing advance (TA) acquisition via at least one of: preamble transmission to the target cell; or user-device-based TA estimation for the target cell.

19. The apparatus of claim 18, wherein the computer program instructions to be executed by the one or more processors in association with the at least one data storage are configured for carrying out: performing, before initiation of the CLTM cell switch execution to the target cell, at least one of the one or more preparation actions based on one or more of the preparation actions not causing interruption to scheduling of a source cell.

20. The apparatus of claim 18, wherein the computer program instructions to be executed by the one or more processors in association with the at least one data storage are configured for carrying out: performing at least one of the one or more preparation actions during the CLTM cell switch execution to the target cell based on one or more of the preparation actions causing an interruption to scheduling of a source cell.

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