Indication of capability to handle radio resource control settings for handover

Abstract

Various example embodiments relate to a cell switch in a mobile communications network, in which a user equipment receives a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure, determines whether the UE can pre-process at least a portion of the RRC reconfiguration message related to the LTM before receiving a cell switch command to perform the cell switch, performs pre-processing of at least a portion of the LTM-related portion of the received RRC reconfiguration message, and transmits, before receiving the cell switch command, a message including an indication of the pre-processed portion of the LTM-related portion of the radio resource control reconfiguration message towards a network node of a radio access network to which the user equipment is connected.

Description

[Technical Field]

[0001] Various exemplary embodiments relate generally to the field of mobile communication networks. Some exemplary embodiments relate to signaling indicating user equipment capabilities for handling radio resource control configuration for handover. [Background technology]

[0002] A wireless communication network may be implemented as a cellular network, in which user equipment (UE) is served by cells of the network. As a UE moves within the network, the serving cell may change, for example, according to 3GPP (3rd Generation Partnership Project) radio access network (RAN) Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedures, to maintain connectivity with the UE. Summary of the Invention

[0003] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended for use in limiting the scope of the claimed subject matter.

[0004] Exemplary embodiments of the present disclosure allow for reduced delays in handovers or cell switches. This and other benefits can be achieved by the features of the independent claims. Further exemplary embodiments are provided in the dependent claims, the description, and the drawings.

[0005] According to a first aspect, a method is disclosed that may include receiving, by a user equipment, a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure, determining whether the user equipment can pre-process at least a portion of the LTM-related radio resource control reconfiguration message before receiving a cell switch command to perform a cell switch, performing pre-processing of at least a portion of the LTM-related portion of the received RRC reconfiguration message, and transmitting, before receiving the cell switch command, a message including an indication of the pre-processed LTM-related portion of the radio resource control reconfiguration message toward a network node of a radio access network to which the user equipment is connected.

[0006] According to an exemplary embodiment of the first aspect, the network node is a central node of a radio access network, and the message sent to the central node is an RRC reconfiguration complete message including an LTM indication indicating the status of pre-processing of the LTM preparation operation.

[0007] According to an exemplary embodiment of the first aspect, the network node is a distributed node of a radio access network, and the message sent to the distributed node is an L2 (Layer 2) message.

[0008] According to an exemplary embodiment of the first aspect, the L2 message includes a medium access control (MAC) control element (CE) message that includes an LTM indication that indicates the status of pre-processing of the LTM preparation operation.

[0009] According to an exemplary embodiment of the first aspect, the network node is a distributed node of a radio access network, and the message sent to the distributed node is an L1 measurement report message including an LTM indication indicating the status of pre-processing of the LTM preparation operation.

[0010] According to an exemplary embodiment of the second aspect, the LTM indication indicating the status of pre-processing of the LTM preparation operation includes an indication of whether at least one of operations related to Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation has been performed.

[0011] According to an exemplary embodiment of the first aspect, the indication regarding the preprocessed portion includes an indication regarding the remaining LTM execution time delay.

[0012] According to a second aspect, a method is disclosed that may include receiving, by a user equipment, a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure and including instructions for preprocessing at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related portion of a received RRC message, determining whether the user equipment can preprocess at least a portion of the indicated Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related radio resource control reconfiguration message prior to receiving a cell switch command to perform a cell switch, and performing preprocessing of at least a portion of the indicated Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related portion of the received RRC message.

[0013] According to an exemplary embodiment of the second aspect, the method may comprise, after the performed pre-processing is completed, transmitting an L1 measurement report message towards a network node of a radio access network to which the user equipment is connected.

[0014] According to an exemplary embodiment of the second aspect, the method may include, in response to receiving an L2 message including a cell switch command, processing a non-preprocessed Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related portion of the received RRC reconfiguration message, extracting information of a target cell to switch to from the cell switch command, and performing a random access procedure towards the target cell.

[0015] According to an exemplary embodiment of the second aspect, the L2 message comprises a Media Access Control (MAC) Control Element (CE) message.

[0016] According to a third aspect, a method is disclosed that may include: establishing, by a user equipment (UE), a connection to a network node of a radio access network; sending, by the UE, an indication of UE capabilities toward the network node regarding capabilities for supporting Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) operations and regarding support for pre-processing of at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related radio resource control reconfiguration message before receiving a cell switch command to perform a cell switch; receiving, by the user equipment, a radio resource control (RRC) reconfiguration message related to the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure; and performing pre-processing of at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related portion of the received RRC message.

[0017] According to an exemplary embodiment of the third aspect, the indication of the UE capabilities is sent to the network node during or after establishment of a connection to the network node.

[0018] According to an exemplary embodiment of the third aspect, the indication of the UE capabilities is sent to the network node before performing the LTM preparation, or the indication of the UE capabilities is sent to the network node before or together with the L3 measurement report.

[0019] According to an exemplary embodiment of the third aspect, pre-processing at least some of the Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) related portions of the received RRC reconfiguration message includes pre-processing at least one of Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation related operations.

[0020] According to a fourth aspect, a method is disclosed that may include: transmitting, by a network node of a radio access network, a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure to a user equipment; receiving, from the user equipment connected to the radio access network, a message including an indication of a preprocessed portion of the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related portion of the radio resource control reconfiguration message prior to receiving a cell switch command; and configuring at least one delay value of the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure of the user equipment based on the indication of the preprocessed portion of the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related portion of the radio resource control reconfiguration message by the user equipment.

[0021] According to an exemplary embodiment of the fourth aspect, the network node is an aggregation node of a radio access network, and the message received by the aggregation node is an RRC reconfiguration complete message including an LTM indication indicating a status of pre-processing of the LTM preparation operation.

[0022] According to an exemplary embodiment of the fourth aspect, the network node is a distributed node of a radio access network, and the message received by the distributed node is an L2 message including an LTM indication indicating the status of pre-processing of the LTM preparation operation.

[0023] According to an exemplary embodiment of the fourth aspect, the L2 message comprises a Media Access Control (MAC) Control Element (CE) message.

[0024] According to an exemplary embodiment of the fourth aspect, the network node is a distributed node of a radio access network, and the message received by the distributed node is an L1 measurement report message including an LTM indication indicating a status of pre-processing of the LTM preparation operation.

[0025] According to an exemplary embodiment of the fourth aspect, the LTM indication indicating the status of pre-processing of the LTM preparation operation includes an indication of whether at least one of operations related to Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation has been performed.

[0026] According to an exemplary embodiment of the fourth aspect, the indication regarding the preprocessed portion includes an indication regarding the remaining LTM execution time delay.

[0027] According to a fifth aspect, a method is disclosed that may include transmitting, by a network node to a user equipment, a Radio Resource Control (RRC) Reconfiguration message associated with a Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) procedure and including instructions for preprocessing at least a portion of a Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM)-related portion of an RRC message.

[0028] According to a sixth aspect, a method is disclosed that may include establishing a connection with a user equipment (UE) by a network node of a radio access network, receiving, from the UE, an indication of UE capabilities regarding capability to support a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure and regarding support of pre-processing of at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related radio resource control reconfiguration message before receiving a cell switch command to perform a cell switch, and configuring at least one delay value of the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure of the user equipment based on the indication regarding the pre-processed portion of the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related portion of the radio resource control reconfiguration message by the user equipment.

[0029] According to an exemplary embodiment of the sixth aspect, the indication of the UE capabilities is received during or after establishment of a connection with the UE.

[0030] According to an exemplary embodiment of the sixth aspect, the indication of UE capabilities is received before or together with the L3 measurement report.

[0031] According to an exemplary embodiment of any of the first to sixth aspects, pre-processing at least a portion of the Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) related portions of the received RRC reconfiguration message includes pre-processing at least one of Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation related operations.

[0032] According to a seventh aspect, an apparatus is disclosed, which may comprise means for performing a method according to any of the first to sixth aspects or an exemplary embodiment of any of the first to sixth aspects.

[0033] According to an eighth aspect, a computer program or computer program product is disclosed, which may include instructions that, when executed by an apparatus, cause the apparatus to perform a method according to any of the first to sixth aspects or an exemplary embodiment of any of the first to sixth aspects.

[0034] According to a ninth aspect, an apparatus is disclosed that may include at least one processor and at least one memory that stores instructions that, when executed by the at least one processor, cause the apparatus to at least: receive, by a user equipment, a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure; determine whether the user equipment can pre-process at least a portion of the radio resource control reconfiguration message related to the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) before receiving a cell switch command to perform a cell switch; perform pre-processing of at least a portion of the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related portion of the received RRC reconfiguration message; and send, before receiving the cell switch command, a message including an indication of the pre-processed portion of the radio resource control reconfiguration message toward a network node of a radio access network to which the user equipment is connected.

[0035] According to an exemplary embodiment of the ninth aspect, the network node is an aggregation node of a radio access network, and the message sent to the aggregation node is an RRC reconfiguration complete message including an LTM indication indicating a status of pre-processing of the LTM preparation operation.

[0036] According to an exemplary embodiment of the ninth aspect, the network node is a distributed node of a radio access network, and the message sent to the distributed node is an L2 (Layer 2) message.

[0037] According to an exemplary embodiment of the ninth aspect, the L2 message includes a media access control (MAC) control element (CE) message that includes an LTM indication that indicates a status of pre-processing of the LTM preparation operation.

[0038] According to an exemplary embodiment of the ninth aspect, the network node is a distributed node of a radio access network, and the message sent to the distributed node is an L1 measurement report message including an LTM indication indicating the status of pre-processing of the LTM preparation operation.

[0039] According to an exemplary embodiment of the second aspect, the LTM indication indicating the status of pre-processing of the LTM preparation operation includes an indication of whether at least one of operations related to Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation has been performed.

[0040] According to an exemplary embodiment of the ninth aspect, the indication regarding the pre-processed portion includes an indication regarding the remaining LTM execution time delay.

[0041] According to a tenth aspect, an apparatus is disclosed that may include at least one processor and at least one memory that stores instructions that, when executed by the at least one processor, cause the apparatus to at least: receive, by a user equipment, a radio resource control (RRC) reconfiguration message associated with a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure and including instructions for pre-processing at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related portion of a received RRC message; determine, prior to reception of a cell switch command to perform a cell switch, whether the user equipment can pre-process at least a portion of the indicated Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related radio resource control reconfiguration message; and perform pre-processing of at least a portion of the indicated Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related portion of the received RRC message.

[0042] According to an exemplary embodiment of the tenth aspect, the instructions, when executed by the at least one processor, are configured to cause the apparatus to transmit an L1 measurement report message towards a network node of a radio access network to which the user equipment is connected after the performed pre-processing is completed.

[0043] According to an exemplary embodiment of the tenth aspect, the instructions, when executed by at least one processor, are configured to cause the apparatus, in response to receiving an L2 message including a cell switch command, to process a non-preprocessed Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related portion of the received RRC reconfiguration message, extract information of a target cell to switch to from the cell switch command, and perform a random access procedure towards the target cell.

[0044] According to an exemplary embodiment of the tenth aspect, the L2 message includes a Media Access Control (MAC) Control Element (CE) message.

[0045] According to an eleventh aspect, an apparatus is disclosed that may include at least one processor and at least one memory that stores instructions that, when executed by the at least one processor, cause the apparatus to at least: establish, by a user equipment (UE), a connection to a network node of a radio access network; send, by the UE, an indication of UE capabilities toward the network node regarding functionality supporting Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) operations and regarding supporting pre-processing of at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related radio resource control reconfiguration message prior to receiving a cell switch command to perform a cell switch; receive, by the user equipment, a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure; and perform pre-processing of at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related portion of the received RRC message.

[0046] According to an exemplary embodiment of the eleventh aspect, the instructions, when executed by the at least one processor, are configured to cause the apparatus to transmit an indication of UE capabilities to a network node during or after establishment of a connection to the network node.

[0047] According to an exemplary embodiment of the eleventh aspect, the instructions, when executed by the at least one processor, are configured to cause the apparatus to send an indication of UE capabilities to the network node before performing LTM preparation, or to send the indication of UE capabilities to the network node before or together with an L3 measurement report.

[0048] According to an exemplary embodiment of the eleventh aspect, pre-processing at least some of the Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) related portions of the received RRC reconfiguration message includes pre-processing at least one of Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation related operations.

[0049] According to a twelfth aspect, an apparatus is disclosed that may include at least one processor and at least one memory that stores instructions that, when executed by the at least one processor, cause the apparatus to at least: transmit, by a network node of a radio access network, a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure to a user equipment; receive, from a user equipment connected to the radio access network, a message including an indication of a preprocessed portion of the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related portion of the radio resource control reconfiguration message prior to reception of a cell switch command; and configure at least one delay value of the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure of the user equipment based on the indication of the preprocessed portion of the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related portion of the radio resource control reconfiguration message by the user equipment.

[0050] According to an exemplary embodiment of the twelfth aspect, the network node is an aggregation node of a radio access network, and the message received by the aggregation node is an RRC reconfiguration complete message including an LTM indication indicating a status of pre-processing of the LTM preparation operation.

[0051] According to an exemplary embodiment of the twelfth aspect, the network node is a distributed node of a radio access network, and the message received by the distributed node is an L2 message including an LTM indication indicating the status of pre-processing of the LTM preparation operation.

[0052] According to an exemplary embodiment of the twelfth aspect, the L2 message includes a Media Access Control (MAC) Control Element (CE) message.

[0053] According to an exemplary embodiment of the twelfth aspect, the network node is a distributed node of a radio access network, and the message received by the distributed node is an L1 measurement report message including an LTM indication indicating a status of pre-processing of the LTM preparation operation.

[0054] According to an exemplary embodiment of the twelfth aspect, the LTM indication indicating the status of pre-processing of the LTM preparation operation includes an indication of whether at least one of operations related to Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation has been performed.

[0055] According to an exemplary embodiment of the twelfth aspect, the indication regarding the preprocessed portion includes an indication regarding the remaining LTM execution time delay.

[0056] According to a thirteenth aspect, an apparatus is disclosed that may include at least one processor and at least one memory that, when executed by the at least one processor, causes the apparatus to at least cause a network node to transmit, to a user equipment, a Radio Resource Control (RRC) Reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) procedure, the RRC message including instructions for pre-processing at least a portion of a Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM)-related portion of an RRC message.

[0057] According to a fourteenth aspect, an apparatus is disclosed that may include at least one processor and at least one memory that stores instructions that, when executed by the at least one processor, cause the apparatus to at least: establish a connection with a user equipment (UE) by a network node of a radio access network; receive, from the UE, an indication of UE capabilities regarding supporting a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure and regarding supporting pre-processing of at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related radio resource control reconfiguration message before receiving a cell switch command to perform a cell switch; and configure at least one delay value for the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure of the user equipment based on the indication regarding the pre-processed portion of the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related portion of the radio resource control reconfiguration message by the user equipment.

[0058] According to an exemplary embodiment of the fourteenth aspect, the instructions, when executed by the at least one processor, are configured to cause the apparatus to receive an indication of UE capabilities during or after establishment of a connection with the UE.

[0059] According to an exemplary embodiment of the fourteenth aspect, the instructions, when executed by the at least one processor, are configured to cause the apparatus to receive an indication of the capability prior to or along with an L3 measurement report.

[0060] According to an exemplary embodiment of any of the ninth to fourteenth aspects, pre-processing at least a portion of the portion of the received RRC reconfiguration message related to Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) includes pre-processing at least one of Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation related operations.

[0061] According to a fifteenth aspect, a (non-transitory) computer-readable medium is disclosed, which may include program instructions that, when executed by an apparatus, cause the apparatus to perform a method according to any of the first to sixth aspects or an exemplary embodiment of any of the first to sixth aspects.

[0062] Exemplary embodiments of the present disclosure may therefore provide an apparatus, method, computer program, computer program product, or computer-readable medium that enables handover or cell switch with short delays. Any exemplary embodiment may be combined with one or more other exemplary embodiments. These and other aspects of the present disclosure will become apparent from the exemplary embodiments described below. According to some aspects, the subject matter of the independent claims is provided. Other aspects are defined in the dependent claims.

[0063] The accompanying drawings, which are included to provide a further understanding of the example embodiments and constitute a part of this specification, illustrate example embodiments and, together with the description, help to explain the example embodiments. [Brief explanation of the drawings]

[0064] [Figure 1] FIG. 1 illustrates an example of a communication network. [Figure 2] FIG. 1 illustrates an example of components of a 5G new radio (NR) network topology. [Figure 3] FIG. 1 illustrates an example of an apparatus configured to implement one or more exemplary embodiments. [Figure 4] FIG. 1 illustrates an example of delays associated with a Layer 3 (L3) handover procedure. [Figure 5A] A diagram showing an example of message sequence and operation for L1 / L2 triggered mobility. [Figure 5B] A diagram showing an example of message sequence and operation for L1 / L2 triggered mobility. [Figure 6] FIG. 1 illustrates an example of UE capability exchange for LTM. [Figure 7A] FIG. 10 is a diagram illustrating an example of distribution of LTM function information. [Figure 7B] FIG. 10 is a diagram illustrating an example of distribution of LTM function information. [Figure 8A] A diagram showing an example of a message sequence and operation when sending an LTM uplink indication in an RRC reconfiguration complete message. [Figure 8B] A diagram showing an example of a message sequence and operation when sending an LTM uplink indication in an RRC reconfiguration complete message. [Figure 9A] A diagram showing an example of a message sequence and operation when transmitting an LTM uplink indication in a media access control (MAC) control element (CE). [Figure 9B] A diagram showing an example of a message sequence and operation when transmitting an LTM uplink indication in a media access control (MAC) control element (CE). [Figure 10A] A diagram showing an example of a message sequence and operation when transmitting an LTM uplink indication at a MAC CE. [Figure 10B] A diagram showing an example of a message sequence and operation when transmitting an LTM uplink indication at a MAC CE. [Figure 11A] A diagram showing an example of message sequences and operations when RRC configuration indicates LTM priority. [Figure 11B] A diagram showing an example of message sequences and operations when RRC configuration indicates LTM priority. [Figure 12] FIG. 10 illustrates an example of a method for indicating the ability to pre-process RRC reconfiguration before a cell switch. [Figure 13] FIG. 10 illustrates an example of a method for pre-processing RRC reconfiguration. [Figure 14] FIG. 10 illustrates an example of a method for indicating UE capabilities for pre-processing RRC reconfiguration before a cell switch. [Figure 15] A diagram showing an example of a method for setting an LTM delay based on an indication of a pre-processed portion of an RRC reconfiguration message for LTM. [Figure 16] A diagram showing a method for instructing a UE to pre-process at least a portion of an LTM-related portion of an RRC message. [Figure 17] A diagram illustrating a method for setting the LTM delay based on an indication of UE capability to support LTM pre-processing. DETAILED DESCRIPTION OF THE INVENTION

[0065] In the accompanying drawings, like reference numerals are used to denote like parts.

[0066] Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. The detailed description presented below in conjunction with the accompanying drawings is intended to describe the examples and is not intended to represent the only manner in which the examples may be constructed or utilized. The description sets forth the functions of the examples and the sequence of steps for constructing and operating the examples, although the same or equivalent functions and sequences may be accomplished in different examples.

[0067] A UE may connect to different cells of the network and use L1 and / or L2 signaling to perform inter-cell mobility (handover) procedures, e.g., a cell switch within or between distributed units (DUs) within a single central unit (CU) of an access node. In L1 / L2 triggered mobility, a media access control (MAC) control element or downlink control information (DCI) may trigger the cell switch. L1 measurements may be used during the cell switch execution phase. Such procedures may be referred to as L1 / L2 mobility. Exemplary embodiments of the present disclosure may provide L1 / L2-based inter-cell mobility mechanisms and procedures that enable reduced latency in L1 / L2 triggered mobility (LTM), enable configuration and maintenance of multiple candidate cells to enable rapid application of configurations to the candidate cells, provide mechanisms for dynamic switching between candidate serving cells (including special cells, SpCells, and secondary cells, SCells, for applicable scenarios based on L1 / L2 signaling), provide L1 extensions for inter-cell beam management (e.g., including L1 measurement and reporting and / or beam indication), enable timing advance management, and provide aggregation unit (CU) / distributed unit (DU) interface signaling to support LTM. The distribution of processing in an access node to a CU and one or more DUs is described with reference to FIG. 1 . The described L1 / L2-based inter-cell mobility procedures may be applicable to the following scenarios: - 5G New Radio (NR) dual connectivity (NR-DC) with standalone, carrier aggregation (CA), or serving cell change within one configured grant (CG); - Within a DU and between DUs within a CU (applicable to standalone and CA), - both intra-frequency and inter-frequency mobility; - Both Frequency Range 1 (FR1: Frequency Range1) and Frequency Range 2 (FR2: Frequency Range2), or - The source and target cells are synchronous or asynchronous.

[0068] Exemplary embodiments of the present disclosure enable reduced handover (inter-cell mobility) latency, for example, in the scenarios described above. In L1 / L2 triggered mobility (LTM), the UE may be configured to report L1 beam measurements to a serving DU (source DU). The serving DU may determine when to trigger a handover based on the L1 beam measurements. This can simplify many of the network and UE mobility procedures, as well as reduce mobility disruption or delay. Furthermore, network data forwarding and scheduling can also benefit from LTM. In LTM, the UE may maintain configurations for multiple cells, allowing for rapid application of each configuration. LTM may or may not involve a serving cell change and may use a random access channel (RACH) or be RACH-less.

[0069] In LTM, the serving DU may trigger the execution of the prepared target cell configuration based on lower layer (L1 / L2) signaling, which may include, for example, a media access control (MAC) control element (CE) or downlink control information (DCI). Once the serving DU triggers the cell change, it notifies the CU, which may stop sending RRC reconfiguration messages over the radio link of the serving cell and start forwarding data to the target cell.

[0070] The LTM may use L1 measurements, which have the benefit of faster reaction time to radio link degradation in the serving link, for example, since the network can save delays introduced by Layer 3 (L3) filtering and time-to-trigger (TTT) delays for handover decisions, thereby reducing the number of radio link failures compared to handovers that are not L1 / L2 based.

[0071] Figure 1 illustrates an example of a split access node architecture. The access node, represented throughout this description as gNB 120, may be functionally and / or physically split into a aggregation unit (CU) 128 and one or more distributed units (DUs), which in this example are two DUs 122-1 and 122-2. The CU 128 may also be referred to as a gNB-CU, and the DUs may also be referred to as gNB-DUs. The CU 128 may comprise a control plane (CP) entity and a user plane (UP) entity, represented as gNB-CU-CP 124 and gNB-CU-UP 126, respectively. The gNB-CU-CP 124 may be configured to control communication of signaling data, enabling the transfer of user data / application data in the user plane. User plane communication may be provided by one or more gNB-CU-UPs 126 associated with the gNB-CU-CP 124. The CU 128 and DUs 122-1, 122-2 may be configured to provide radio access network (RAN) services to devices represented by user equipment (UE) 110 in one or more cells 112.

[0072] The control plane entity and user plane entity of CU 128 may communicate via a communication interface, such as an E1 interface. CU 128 may communicate with a DU through a communication interface, such as an F1 interface. The F1 interface may include a control plane interface (F1-C) and a user plane interface (F1-U) between the DU and the control plane entity and user plane entity of CU 128, respectively. Although two DUs are shown in Figure 1, a CU may generally be associated with one or more DUs.

[0073] The CU / DU split architecture enables RAN separation, which not only allows operators to use different vendors for different network nodes, but also allows network vendors to split their network implementations for scalability. For example, the control plane and user plane may be separated into their own entities, allowing the control plane and user plane functions to be scaled separately. However, this separation may be (almost) invisible to the user equipment (UE), and therefore the protocol layers on the UE side may be (almost) unaware of the separation, except for a small part that the UE may implicitly determine from the relevant radio resource control (RRC) configuration. The network may be configured to explicitly control which parts of the protocol stack are reconfigured in the case of intra-DU or inter-DU handover. This may be included in the RRC process, and therefore the RRC delay may be variable or fixed, but will be different in different scenarios.

[0074] The UE 110 may access application services via a RAN, which may comprise one or more gNBs 120. The UE 110 may communicate with the gNBs 120 over an air interface configured, for example, based on the 5G New Radio (NR) standard defined by the 3rd Generation Partnership Project (3GPP). The communication network 100 may thus comprise a wireless communication network.

[0075] The communication network 100 may operate based on a protocol stack including multiple protocol layers. The protocol stack may be arranged based on the open systems interconnection (OSI) model or a layer model of a particular standard (e.g., the 3GPP standard). In one example, the protocol stack may include a service data adaptation protocol (SDAP) layer that may receive data from an application layer for transmission. The SDAP layer may be configured to exchange data with a packet data convergence (PDCP) layer. The PDCP layer may be responsible for generating data bursts including one or more data packets, for example, based on data obtained from the SDAP layer.

[0076] The PDCP layer may provide data to one or more instances of the radio link control (RLC) layer. PDCP data may be transmitted, for example, over one or more RLC transmission legs. Each RLC instance may be associated with a corresponding MAC instance in the MAC layer (Layer 2). The MAC layer may perform mapping between logical channels in higher layers and transport channels in the physical layer and handle the multiplexing and demultiplexing of MAC service data units (SDUs). The MAC layer may also provide error correction functionality based on packet retransmission, for example, according to a hybrid automatic repeat request (HARQ) process. Physically separate transmission legs may be provided by the physical (PHY) layer, also known as Layer 1 (L1). The RLC, MAC, and L1 functionalities may reside in the DUs 122-1, 122-2. Corresponding protocol stacks may be applied in both the gNB 120 and the UE 110.

[0077] In a split access node architecture, some of the protocol layers may be implemented in the CU 128. In the example of FIG. 1, the CU 128 (e.g., the CU-UP 126) may be configured to handle upper layers of the protocol stack, such as the SDAP layer and the PDCP layer. Additionally, the CU 128 (e.g., the CU-CP 124) may be configured to handle radio resource control (RRC) operations. The DUs 122-1 and 122-2 may be configured to handle lower layers of the protocol stack, such as RLC, MAC, and L1. A user plane (U-plane) control function may interact with the MAC layer to encapsulate and / or decapsulate RRC data received from the CU-CP 124 into MAC packets and / or decapsulate RRC data from the MAC packets and provide the RRC data to the CU-CP 124. The radio units of the DUs 122-1 and 122-2 may transmit and receive data to and from the UE over the air interface.

[0078] As mentioned above, one CU may comprise or be configured to control several DUs. Furthermore, one DU may serve multiple cells, e.g., tens of cells. Providing an RRC layer in the CU 128 may enable proper control of the mobility of the UE 110 and may also enable the CU to act as an aggregated resource manager for the UE 110. The DUs 122-1, 122-2 may also include resource managers that control the usage of lower layer radio parameters, e.g., periodic physical uplink control channel (PUCCH) resources, and computing resources of several central computing units (CPUs).

[0079] The communication network 100 may include other network functions, network devices, or protocols in addition to or instead of those mentioned above. While some embodiments are described in the context of a 5G network, it should be understood that embodiments of the present disclosure are not limited to this example network. The example embodiments may therefore apply to any current or future communication network. An apparatus may include one or more of the protocol layers described herein or may be configured to implement them, for example, via software. FIG. 2 illustrates example components of a 5G New Radio (NR) network topology. As a user equipment (UE) moves through a wireless communication system, the UE may move through radio coverage areas (cells) supported by one or more radio access network nodes. Maintaining the ability of a UE to effectively communicate with a wireless communication system as it moves through radio coverage areas is typically referred to as mobility. The operating characteristics of cells supported by network access nodes within a wireless communication network may vary. A wireless communication system may include various Transmission and Reception Points (TRPs).

[0080] 5G NR networks are expected to use multiple transmission and reception points (mTRPs) to improve reliability, coverage, and capacity performance through flexible deployment scenarios. Multiple TRPs operate to mitigate inter-cell interference through dynamic coordination between multiple TRPs and enable joint scheduling and transmission / reception. Wireless devices, such as UEs, at the cell edge may be served by multiple TRPs to improve signal transmission and reception, resulting in higher throughput. The following description may provide further details of alternatives, modifications, and variations in 5G NR networks. A gNB may comprise a node that provides termination of NR user plane and control plane protocols to the UE 110 and is connected to the 5G NR via an NG interface, for example, according to 3GPP TS38.300V16.6.0(3021-06) section 3.2, which is incorporated herein by reference.

[0081] The gNB Central Unit (gNB-CU) comprises, for example, a logical node that hosts, for example, the gNB's RRC (Radio Resource Control), SDAP (Service Data Adaptation Protocol), and PDCP (Packet Data Convergence Protocol) protocols, or the en-gNB's RRC and PDCP protocols that control the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface connected to the gNB-DUs.

[0082] The gNB Distributed Unit (gNB-DU) comprises, for example, a logical node that hosts, for example, the RLC (Radio Link Control), MAC (Medium Access Control), and PHY (Physical) layers of a gNB or en-gNB, and the operation of the logical node is partially controlled by the gNB-CU. One gNB-DU supports one or multiple cells. One cell may be supported by only one gNB-DU. The gNB-DU terminates the F1 interface connected to the gNB-CU.

[0083] The gNB-CU Control Plane (gNB-CU-CP) comprises, for example, a logical node that hosts the control plane part of the RRC and PDCP protocols of, for example, the en-gNB or the gNB-CU of a gNB. The gNB-CU-CP terminates the E1 interface connected to the gNB-CU-UP and the F1-C interface connected to the gNB-DU.

[0084] The gNB-CU User Plane (gNB-CU-UP) comprises, for example, a logical node that hosts, for example, the user plane portion of the PDCP protocol of the gNB-CU of the en-gNB and the user plane portions of the PDCP and SDAP protocols of the gNB-CU of the gNB. The gNB-CU-UP terminates the E1 interface connected to the gNB-CU-CP and the F1-U interface connected to the gNB-DU, for example, according to 3GPP TS38.501V16.6.0(3021-07) section 3.1, which is incorporated by reference.

[0085] Various functional divisions are possible between the aggregation unit and the distribution unit, for example the following options:

[0086] Option A (similar split to 1A): The functional split in this option is similar to the 1A architecture in DC. RRC is in the aggregation unit. PDCP, RLC, MAC, physical layer, and RF are in the distributed units.

[0087] Option B (Similar division to 3C): The division of functions in this option is similar to the 3C architecture in DC. RRC and PDCP are in the aggregation unit. RLC, MAC, physical layer, and RF are in the distributed units.

[0088] Option C (intra-RLC split): The lower RLC (partial functions of RLC), MAC, physical layer, and RF are in the distributed unit. The PDCP and upper RLC (other partial functions of RLC) are in the aggregation unit.

[0089] Option D (RLC-MAC Split): MAC, physical layer, and RF are in the distributed unit. PDCP and RLC are in the aggregation unit.

[0090] Otherwise, for example, according to 3GPP TR38.801V14.0.0(2017-03) section 11, which is incorporated herein by reference.

[0091] A gNB may support various protocol layers, for example, Layer 1 (L1), i.e., the physical layer. Layer 2 (L2) of NR is divided into Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Service Data Adaptation Protocol (SDAP) sublayers, where, for example, the physical layer provides transport channels to the MAC sublayer, which provides logical channels to the RLC sublayer, which provides RLC channels to the PDCP sublayer, which provides radio bearers to the SDAP sublayer, which provides QoS flows to 5GC, Comp. can refer to header compression, Segm. can refer to segmentation, and control channels include (BCCH, PCCH).

[0092] Layer 3 (L3) includes, for example, Radio Resource Control (RRC), for example according to 3GPP TS38.300V16.6.0(3021-06) clause 6, which is incorporated herein by reference.

[0093] A RAN (Radio Access Network) node, network node, aggregation node, or distributed node, e.g., a gNB, base station, gNB CU, gNB DU, or portion thereof, may be implemented using, e.g., an apparatus comprising at least one processor and / or at least one memory (containing computer-readable instructions (computer programs)) and configured to, e.g., support, provide, and / or process functionality and / or features related to the CU and / or DU, and / or at least one protocol (sub)layer of the RAN (Radio Access Network), e.g., Layer 2 and / or Layer 3. They may also be implemented using specific means configured to perform respective specific tasks, e.g., Layer 3 means for performing Layer 3 operations, Layer 2 means for performing Layer 2 operations, etc. An aggregation node may, e.g., implement the functionality of the CU-CP and / or CP-UP.

[0094] The gNB CU and gNB DU units may, for example, coexist or be physically separated. The gNB DU may even be further divided, for example, into two parts, one with processing equipment and one with antennas. The aggregation unit (CU) may also be referred to as a BBU / REC / RCC / C-RAN / V-RAN, O-RAN, or part thereof. The distributed unit (DU) may also be referred to as an RRH / RRU / RE / RU, or part thereof.

[0095] The gNB-DU supports one or more cells and can thereby function, for example, as a serving cell for a user equipment (UE).

[0096] In other words, a 5G base station or "network node", called a gNB, can be divided into two physical entities called a CU (aggregated unit) and a DU (distributed unit).

[0097] The CU provides support for the upper layers of the protocol stack, such as SDAP, PDCP, and RRC (and especially Layer 3 protocols like RRC), while the DU provides support for the lower layers of the protocol stack, such as RLC, MAC, and the physical layer (especially Layer 1 protocols like the physical layer and Layer 2 protocols like RLC and MAC). Note also that the SDAP layer does not exist when the CU is connected to a 4G core network, and a 5G core network should be equipped to support SDAP. There may be a single CU per gNB, but one CU may control multiple DUs; for example, more than 100 DUs may be connected to one CU.

[0098] Each DU can support one or multiple cells, so unlike 4G base stations, one gNB can control hundreds of cells. Also, note that the interface between the CU and the DU is called F1, which should be an open interface according to 3GPP, so one CU of vendor X is connected to another DU of vendor Y.

[0099] A user equipment (UE) may include a wireless or mobile device, a device with a radio interface for interfacing with a radio access network (RAN), a smartphone, an in-vehicle device, an IoT device, an M2M device, etc. Such a UE or device may include at least one processor and at least one memory including computer program code configured by the at least one processor to cause the device to perform at least predetermined operations, such as, for example, an RRC connection to the RAN. The UE may be configured, for example, to generate a message (e.g., including a cell ID) to be transmitted over the air toward the RAN (e.g., to reach and communicate with a serving cell). The UE may generate, send, and receive RRC messages including one or more RRC packet data units (PDUs).

[0100] A UE may have various states (eg, according to 3GPP TS38.331V16.5.0(3021-06) sections 42.1 and 4.4, which are incorporated by reference).

[0101] A UE may be in, for example, either an RRC_CONNECTED state or an RRC_INACTIVE state when an RRC connection is established.

[0102] In the RRC_CONNECTED state, a UE may store AS context, transfer unicast data to / from the UE, monitor a control channel associated with the shared data channel to determine if data is scheduled on the data channel, provide channel quality and feedback information, and / or perform neighbor cell measurements and measurement reporting.

[0103] The RRC protocol includes, for example, the following main functions: RRC connection control, measurement configuration and reporting, establishing / modifying / releasing measurement configurations (e.g., intra-frequency, inter-frequency, and inter-RAT measurements), setting up and releasing measurement gaps, and / or reporting measurements.

[0104] As networks evolve, inter-cell mobility is being implemented, particularly in 5G New Radio (NR) systems, to be Layer 1 (L1 or PHY layer) or Layer 2 (L2 or MAC layer) centric (L1 / L2 centric) rather than being controlled by the core network. Within the 5G NR framework, a range of different ways of implementing L1 / L2 centric inter-cell mobility are possible and may be selected based on different operating scenarios, as further described below.

[0105] 3 illustrates an example of an apparatus configured to implement one or more exemplary embodiments. The apparatus 300 may comprise a device such as, for example, a user equipment, an access node, an access point, a base station, a wireless network node, or a divided portion thereof, or generally, a device configured to implement the functionality described herein. The apparatus 300 may comprise at least one processor 302. The at least one processor 302 may include, for example, one or more of various processing devices, such as, for example, a coprocessor, a microprocessor, a controller, a digital signal processor (DSP), processing circuitry with or without an associated DSP, or various other processing devices including integrated circuits, such as, for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a microcontroller unit (MCU), a hardware accelerator, a dedicated computer chip, or the like.

[0106] The device 300 may further include at least one memory 304. The memory 304 may be configured to store, for example, computer program code, such as operating system software and application software. The memory 304 may include one or more volatile memory devices, one or more non-volatile memory devices, and / or a combination thereof. The memory may be embodied, for example, as a magnetic storage device (such as a hard disk drive or magnetic tape), a magneto-optical storage device, or a semiconductor memory (such as a masked ROM, a programmable ROM (PROM), an erasable PROM (EPROM), a flash ROM, or a random access memory (RAM)). The memory 304 is presented as an example of a (non-transitory) computer-readable medium. The term "non-transitory" as used herein does not refer to the permanence of the data storage (e.g., RAM vs. ROM), but rather to the medium itself (i.e., tangible, not a signal).

[0107] The device 300 may further comprise a communications interface 308 configured to enable the device 300 to send and receive information. The communications interface 308 may comprise an internal or external communications interface, such as, for example, an E1, F1, F1-C, and / or F2-C interface, or a wireless interface. The device 300 may further comprise other components and / or functionality, such as, for example, a user interface (not shown) comprising at least one input device and / or at least one output device. The input device may take various forms, such as a keyboard, a touch screen, or one or more built-in control buttons. The output device may include, for example, a display, a speaker, etc.

[0108] If the device 300 is configured to perform some functionality, then any one and / or multiple components of the device 300 may be configured to perform this functionality, such as at least one processor 302 and / or at least one memory 304. Furthermore, if at least one processor 302 is configured to perform some functionality, then this functionality may be implemented using program code 306 included in at least one memory 304, for example.

[0109] The functionality described herein may be performed, at least in part, by one or more computer program product components, such as software components. According to an exemplary embodiment, the device 300 includes a processor or processor circuitry, such as a microcontroller, that, when executed, is configured by program code 306 to perform embodiments of the operations and functionality described herein. The program code 306 is presented as an example of instructions that, when executed by the at least one processor 302, cause the device 300 to execute.

[0110] Alternatively or additionally, the functionality described herein may be performed, at least in part, by one or more hardware logic components. Exemplary types of hardware logic components that may be used include, but are not limited to, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), system-on-a-chip systems (SOCs), complex programmable logic devices (CPLDs), graphics processing units (GPUs), etc.

[0111] The apparatus 300 may perform or be configured to cause the performance of the methods described herein, or may comprise means for performing the methods described herein. This means, in one example, comprises at least one processor 302 and at least one memory 304 containing program code 306 configured, when executed by the at least one processor 302, to cause the apparatus 300 to perform the methods. Computer program instructions can generally be executed on a means providing general-purpose processing functionality. Such means may be incorporated, for example, in a personal computer, a smartphone, a network device, etc. The method may therefore be computer-implemented, for example, based on an algorithm executable by a general-purpose processing functionality, an example of which is the at least one processor 302. The means may comprise transmitting or receiving means, for example, one or more wireless transmitters or receivers, which may be coupled or configured to be coupled to one or more antennas or transmitters or receivers of a wired communication interface. While the apparatus 300 is shown as a single device, it should be understood that, wherever applicable, the functionality of the apparatus 300 may be distributed across multiple devices.

[0112] 4 illustrates an example of delays associated with a Layer 3 (L3) handover procedure. UE 110 may receive a candidate configuration indicating one or more target cells for handover. This may result in a processing delay T at UE 110 for processing an RRCReconfiguration message conveying the candidate configuration. RRC (for example, up to 10 ms) may occur. PROC,1 can refer to the UE's processing time before the cell switch command. This may include L2 / L3 reconfiguration, RF (radio frequency) part retuning, baseband retuning, security update, etc. This delay can be up to 20 ms in the same frequency range and up to 40 ms in different frequency ranges. When the target cell appears, there is a measured delay T between the appearance of the target cell and the cell switch command. measAfter receiving the cell switch command, a delay T cmd This delay can be up to 5 ms, for example. cmd After that, there is another processing delay T proc,2 This may occur. proc,2 The duration of is T proc,1 may be similar to and may occur for similar reasons.

[0113] Delay T search may include the time required to search for the target cell. If the target cell is known, this delay may be non-existent, but if the target cell is unknown, it may be, for example, up to 60 ms. Δ This can be caused by the time it takes to obtain fine tracking and complete timing information. Δ depends on the synchronization signal / block measurement timing configuration (SMTC) and can be, for example, 20 ms. margin can be caused by post-processing of the synchronization signal block (SSB) or the channel state information reference signal (CSI-RS). search , T Δ , and T margin may be related to downlink (DL) synchronization.

[0114] Delay T IU may occur due to interruption uncertainty in obtaining the first physical random access channel (PRACH) opportunity in the target cell. RARA delay T may occur between the transmission of the random access (RA) preamble and the reception of the random access response (RAR) by the UE 110. IU and T RAR may be related to uplink (UL) synchronization.

[0115] Delay T first-data A disruption may occur between the receipt of the random access response by the UE 110 and the initiation of data communication with the indicated beam. A disruption may occur between the receipt of the cell switch command and the initiation of data communication with the indicated beam. Data may then be communicated with the new cell and new transmission configuration information (TCI).

[0116] The RRC configuration received by UE 110 may therefore include various settings, and processing the RRC configuration may take a long time. It may require significant effort for UE 110 to verify and process the settings. Therefore, in one approach to handover, UE 110 may receive the RRC configuration, verify the RRC configuration, and process the settings knowing exactly what UE 110 needs to do. For example, in the case of an L3 handover, the time for UE 110 to do this may be T proc,2 It can be shown by

[0117] Furthermore, there are many ways in which a UE can process the RRC configuration. Some UEs may be able to process the entire RRC configuration as soon as they receive it, while other UEs may simply verify the configuration and process it later. Therefore, some handover requirements may be designed based on the worst-case scenario, which may not be optimal for LTM, which aims to minimize processing delays.

[0118] The UE LTM RRC process may include decoding and verification / compliance checking. UE 110 may determine to perform the UE LTM RRC process when it receives a command or when a cell switch command is received. UE 110 typically cannot provide information to the network regarding whether the command process occurs before or after the switch command. UE requirements may therefore also be designed based on a worst-case scenario.

[0119] Exemplary embodiments of the present disclosure provide a method for reducing service interruption time for RRC processing in L1 / L2 triggered handover. This may be achieved by addressing how RRC data is processed at the UE 110. The UE 110 may indicate its RRC processing capabilities to the network, for example, by explicit signaling or by UE capabilities related to this processing.

[0120] Compared to the UE delays associated with L3 handover, at least the following areas of improvement can be identified:

[0121] A first set of methods, referred to herein as Options 1-3, includes example embodiments in which an LTM UL indication (LTM_UL_indication) is signaled from UE 110 to the network. This indication allows the network to understand the status of RRC setup processing at UE 110. Based on this information, the network may determine that UE 110 does not need to process RRC setup immediately upon receiving a cell switch command, thereby reducing the latency of the UE service switch in LTM. Based on the LTM UL indication, the network may determine that UE 110 has performed a syntax and / or compliance check of the RRC setup, for example, an ASN.1 (Abstract Syntax Notation One) validity and / or compliance check.

[0122] A second type of method (option 4) may include, for example, a downlink indication in the RRC reconfiguration command from the network to the UE 110. This indication may request the UE 110 to verify the received RRC-LTM configuration, process the RRC-LTM configuration, and / or prepare the UE 110 for a cell switch prior to receiving the cell switch command, for example, through a MAC CE or DCI.

[0123] The following terminology may be used: LTM may refer to L1 / L2 triggered mobility. Cell switch may include a procedure that triggers a cell change, for example, through an LTM feature. Subsequent LTM may refer to when a cell switch between L1 / L2 mobility candidates occurs without an RRC reconfiguration in between. LTM configuration (LTM_config) may include one or more RRC configurations that include LTM-specific information elements. RRC ASN.1 validation may include generic ASN.1 syntax validation and / or completeness validation. LTM evaluation (LTM_evaluation) may include the UE 110 evaluating the LTM configuration and extracting, for example, one or more of the following information: The LTM_PRIORITY parameter may include an indication of a higher priority for RRC-LTM configuration verification, processing, and / or preparation at the UE 110. The LTM_UL_INDICATION parameter may indicate whether the UE 110 can process the LTM configuration before the cell switch command. The LTM_UL_INDICATION parameter may indicate whether the UE 110 can process the LTM configuration before the cell switch command. The LTM_UL_INDICATION parameter may indicate which parts of the RRC configuration remain unprocessed after the cell switch command. The LTM switch command (LTM_switch_command) may include a cell switch command (e.g., MAC CE or DCI). The LTM measurements (LTM_measurements) may include L1 or L3 handover measurements with or without an uplink indication.

[0124] One or more of the following performance improvements may be targeted: - For L1 / L2 based mobility, security update support can be eliminated. - Upon receiving the candidate cell configuration, ASN.1 decoding and validity / compliance checking of the candidate cell configuration may be performed. In UE processing, the following (non-exhaustive) actions may be performed after receiving a cell switch command: MAC / RLC reset (when configured), RF retuning (e.g., required for inter-frequency), baseband retuning. - Perform DL synchronization to the candidate / target cell prior to reception of the cell switch command, e.g., at least if the target cell is already the active serving cell. - Supports performing tracking and CSI measurements on the tracking reference signal (TRS) of candidate / target cells before / by the cell switch command.

[0125] L1 / L2 based mobility may be configured to support the following Carrier Aggregation (CA) scenarios: PCell (primary cell) change without SCell change or PCell change along with SCell change. Furthermore, support for NR-DC scenarios in L1 / L2 based mobility is provided at least in the case of PSCell (primary and secondary cell) change without the involvement of the master node (MN), i.e., within the SN (secondary node).

[0126] For L1 measurements and beam indication, the following scenarios can be considered: Event reporting or filtering may be supported. Inter-frequency L1 / L2 mobility: Inter-frequency scenarios may generally be supported for L1 / L2 mobility (including mobility to inter-frequency cells that are not the current serving cell), including support for inter-frequency L1 measurements. - A unified TCI framework may be used for beam indication of L1 / L2 mobility.

[0127] For dynamic cell switching, the following scenarios may be considered: - L1 / L2 mobility trigger information may be transmitted in MAC CE. MAC CE or DCI may be used for the actual triggering of L1 / L2 mobility. - The MAC CE for L1 / L2 mobility trigger may include at least a candidate configuration index. - Activating / deactivating SCells (e.g., among SCells related to candidate configuration) simultaneously with L1 / L2 mobility triggered MAC CE. RACH-based (e.g., contention-free random access (CFRA), contention-based random access (CBRA)) and RACH-less procedures for L1 / L2 mobility switch may be supported. RACH-less access may be used, for example, when the UE does not need to acquire timing advance (TA) during a cell switch. -RACH resources in CFRA for L1 / L2 dynamic switching may be provided in RRC configuration or MAC CE. - The MAC CE may indicate the status of the TCI (or other beam information) to be activated for the target cell. - At L1 / L2 cell switch: Whether the UE performs a partial or full MAC reset, whether it re-establishes RLC, and whether it performs data recovery with PDCP may be controlled by the network. This can be configured by RRC. Alternatively or additionally, MAC CE indication may be used.

[0128] 5A and 5B show example message sequences and operations for L1 / L2 triggered mobility. The L1 / L2-related procedures may involve the UE 110, the DU 122-1 (acting as a source DU in this example), the DU 122-2 (target DU), and the CU 128. As shown in FIG. 1, the source DU 122-1 and the target DU 122-2 may be associated with the same CU 128, e.g., controlled by the same CU 128. However, the disclosed L1 / L2 mobility procedures may be performed for DUs associated with different CUs. The operations of the source DU 122-1, the target DU 122-2, and the CU 128 may be performed by an access node, e.g., the gNB 120.

[0129] In operation 501, the UE 110 may send an L3 measurement report to the source DU 122-1.

[0130] In operation 502, the source DU 122-1 may send an L3 measurement report to the CU 128, for example, using UL RRC message transfer.

[0131] In operation 503, the CU 128 may decide to handover. This decision may be based on the L3 measurement report.

[0132] In operation 504, the CU 128 may send a UE context setup request to the target DU 122-2. The UE context setup request may be a CU-initiated context setup request.

[0133] In operation 505, the target DU 122-2 may send a UE context setup response to the CU 128.

[0134] In operation 506, the CU 128 may send a UE context modification request to the source DU 122-1.

[0135] In operation 507, the source DU 122-1 may send a UE context modification response to the CU 128.

[0136] In operation 508, the CU 128 may generate an RRC (re)configuration for LTM (RRC-LTM). The RRC-LTM (re)configuration may include measurement configuration for L1 cell change and / or configuration of a target cell prepared for handover.

[0137] In operation 509, the CU 128 may send an RRC message to the source DU 122-1, for example, using a downlink (DL) RRC message transfer. The RRC message may include the RRC-LTM (re)configuration generated in operation 508.

[0138] According to one approach, operation 509 may be followed by the source DU 122-1 transmitting an RRC reconfiguration message to the UE 110, the UE 110 transmitting an RRC reconfiguration complete message to the source DU 122-1, and the UE 110 periodically transmitting an L1 measurement report to the source DU 122-1, which may trigger a handover. However, operations 510 to 519 described herein allow for a reduced delay when performing a handover. The transmission of the L1 measurement report may initiate a handover execution phase, which may be followed by a handover preparation phase, which may include operations up to, for example, the transmission of the L1 measurement report.

[0139] At operation 510, the source DU 122-1 may transmit an RRC reconfiguration message. The RRC reconfiguration message may include the RRC-LTM (re)configuration (LTM_config) received from the CU 128. The RRC reconfiguration message may include an indication of the priority (LTM_priority) of verifying, processing, or preparing the RRC configuration at the UE 110. The priority indication may be set to a (high) value indicating a request to prioritize the verification, processing, or preparation of the RRC configuration at the UE 110, for example, so that the RRC configuration is verified, processed, or prepared before receiving a cell switch command (see operation 518) at the UE 110. Alternatively, the LTM_config or LTM_priority may be transmitted in some other control message. Operation 510 is presented as an exemplary implementation of option 4 mentioned above.

[0140] In operation 511, UE 110 may perform validation of the received LTM_config. UE 110 may, for example, perform syntax validation, e.g., ASN.1 validation, of the RRC configuration (LTM_config). This may include validation of the ASN.1 syntax of the LTM_config, but may not necessarily include, for example, validation of the completeness of the LTM_config.

[0141] At operation 512, UE 110 may perform LTM evaluation and LTM configuration preparation. UE 110 may, for example, evaluate the feasibility of processing LTM_config (e.g., RRC Delta config). UE 110 may extract the LTM config but not yet apply any part of the LTM config. UE 110 may evaluate the user plane configuration, for example, whether changes are needed to MAC, RLC, PDCP, or SDAP protocol settings, whether RF or baseband retuning is needed to comply with an upcoming cell switch command, or whether UE 110 can access target DU 122-2 in a RACH-less access procedure. UE 110 may determine the delay of this processing based on this evaluation.

[0142] UE 110 may determine the delay based on a fixed time delay calculation. For example, the following delay requirements may be specified: RACH delay 10 ms, RACH-less delay 0, RF retune delay 5 ms (inter-frequency only), baseband retune delay 5 ms (inter-frequency only), MAC if intra-DU 5 ms, MAC if inter-DU 10 ms, RLC delay within DU 5 ms, RLC delay between DU 5 ms, and MAC CE processing 5 ms. When UE 110 receives an RRC configuration that includes pointers specific to these cases, UE 110 may calculate, for example, that the setup delay for RACH-less intra-DU with intra-frequency LTM is RACH-less 0 ms + MAC 5 ms + RLC 5 ms MAC CE (cell switch) 5 ms = 15 ms total. Note that these numbers are for illustrative purposes only.

[0143] UE 110 may generally determine whether it can process the RRC configuration (LTM_config) prior to receiving the cell switch command. UE 110 may estimate a delay associated with processing the RRC configuration (LTM_config). Operations 511 and / or 512 may be initiated by UE 110 in response to receiving the indication of LTM_priority in operation 510.

[0144] In operation 513, UE 110 may send an LTM UL indication to source DU 122-1. The LTM UL indication may include an indication of whether UE 110 can process the RRC configuration (LTM_config) before receiving the cell switch command and / or an indication of an estimated delay. The indication may include an indication that UE 110 has already processed the received RRC configuration (LTM_config), i.e., an indication of completion of processing. According to option 1, the LTM UL indication may be sent in an RRC reconfiguration complete message.

[0145] In operation 514, a transfer of UL RRC messages may be performed between the source DU 122-1 and the (target) CU 128.

[0146] In operation 515, according to option 2, the UE 110 may send an LTM UL indication to the source DU 122-1 in a MAC CE. The MAC CE may be dedicated to the LTM UL indication. For example, no other signaling information may be carried in this MAC CE.

[0147] In operation 516, according to option 3, UE 110 may send an LTM UL indication to source DU 122-1 in an L1 measurement report. Any of options 1-3 may be combined with option 4 (see operation 510). It should also be noted that one or more messages of options 1-3 may be sent (without an LTM UL indication) if an LTM UL indication is provided in another of these messages.

[0148] Alternatively, the LTM UL indication may be implicit. For example, the UE 110 may be configured with the capability to perform RRC pre-processing. If the network (e.g., gNB 120) sets a corresponding configuration flag in the RRC configuration, the network may determine that the UE 110 is configured to perform LTM evaluation before transmitting L1 measurements. Thus, providing an explicit LTM UL indication may not be necessary, for example, if the same information is determined by the network based on UE capability signaling.

[0149] For example, in some examples, the functionality of the LTM RRC delay processing may not be explicitly indicated through the UL indication but may be specified by the UE behavior and requirements, e.g., in a standard. In this case, the network (e.g., gNB 120) may determine that the processing of RRC configuration at UE 110 occurs after / before certain operations in FIG. 4A or 4B, e.g., after any operation before operation 518.

[0150] Alternatively, the UE 110 may provide information on the LTM UL indication as a UE capability. If the UE 110 supports this capability, the network (e.g., the gNB 120) may determine to configure the UE 110 to process the RRC configuration in a specified step. The UE capability may indicate, for example, at least one of the following: - UE 110 is configured to perform (together or separately) ASN.1 validation and LTM evaluation (see operations 511 and 512) in response to receiving the RRC configuration in operation 510, e.g. immediately after operation 510 (e.g. as the next operation following receipt of the RRC configuration). The UE 110 is configured to perform (only) action 511 in response to receiving the RRC configuration in action 510. The UE 110 is configured to process the RRC configuration (LTM_config) between operations 516 and 518. The UE 110 is configured to perform an RRC configuration (LTM_config) process before or after starting L1 measurements. The UE 110 is configured to initiate LTM evaluation in response to receiving an indication of the target DU 122-2 from the network (e.g., the source DU 122-1). Thus, the target DU's configuration may trigger LTM evaluation at the UE 110. - UE 110 may perform LTM processing (e.g., ASN.1 validation / validation) any time before the LTM_switch_command.

[0151] In some examples, LTM evaluation and syntax notation (e.g., ASN.1) validation may be performed simultaneously, e.g., in parallel. UE 110 may decide to perform ASN.1 validation (see act 511) separately from LTM evaluation (see act 512).

[0152] In some examples, the UE 110 may apply the RRC configuration immediately after receiving it. The UE 110 may be configured to do so, for example, if the UE 110 is configured with multi-rx / tx capabilities or if the UE 110 has multiple protocol stacks to which the RRC configuration can be applied. In this case, the UE 110 may switch to a pre-configured RX / TX chain or protocol stack in response to receiving a cell switch command.

[0153] In some examples, UE capabilities may indicate that UE 110 is unable to perform RRC pre-processing. In this case, UE 110 may use L3 handover requirements, or alternatively, may use relaxed measurements (e.g., longer time intervals between measurements or measurement reports) compared to UEs capable of RRC pre-processing. Alternatively, the RRC pre-processing capability may be indicated through an LTM_UL_indication (e.g., in one of options 1-3). RRC pre-processing capability may refer to the ability to process RRC configuration (LTM_config) before a cell switch command.

[0154] The source DU 122-1 may therefore receive the LTM UL indication, for example, in an RRC reconfiguration complete message, in a MAC CE, in an L1 measurement report, or as a UE function of the UE 110. Upon receiving the LTM UL indication, the network (e.g., the source DU 122-1) may assume a different delay profile for the UE 110 than if the indication were absent.

[0155] In operation 517, source DU 122-1 may decide to perform a serving cell change for UE 110. This decision may be based on one or more conditions, for example, the condition of L1 handover measurements reported by UE 110. Source DU 122-1 may set at least one delay value for the handover procedure, for example, one or more of delay values ​​D or T described below, based on an LTM UL indication (e.g., the ability of UE 110 to process RRC reconfiguration before a cell switch command, an estimated delay in that processing, or a completion indication of that processing).

[0156] In L1 / L2 triggered mobility, the LTM delay may include an LTM preparation delay and an LTM execution delay, for example, as follows: D LTM =D LTM_preparation +D LTM_execution When UE 110 receives an RRC message indicating an LTM handover, UE 110 may perform an LTM preparation procedure for the LTM. The LTM RRC preparation delay may include an LTM ASN.1 verification delay and an LTM RRC evaluation delay. T RRC_preparation_delay =T ASN.1_validation +T RRC_LTM_evaluation where: -T RRC_preparation_delay is the RRC pre-processing delay (this processing may include ASN.1 verification delay and LTM RRC configuration evaluation delay), -T ASN.1_validation is the ASN.1 configuration validation delay, and -T RRC_LTM_evaluation is the delay it takes for UE 110 to perform LTM configuration evaluation and extract user plane (MAC / RLC / PDCP / SDAP) and / or L1 processing indication from the RRC LTM command.

[0157] LTM execution time T LTM_executionmay include a UE execution preparation time for LTM. The LTM execution time may start after the UE 110 receives a cell switch command (LTM switch command). For example, T LTM_execution =T RRC_LTM_execution_intra +T LTM_switch_command where: -T RRC_execution is the delay of the UE to apply the LTM RRC configuration on L1 and L2 as indicated by the RRC command (RRC configuration), and -T LTM_switch_command is the delay in extracting the target cell information from the switch command and applying the LTM RRC configuration.

[0158] The LTM processing requirements may be divided into intra-frequency and inter-frequency in terms of LTM execution time, for example as presented in the table below. [Table 1]

[0159] Therefore, due to the high speed of LTM, the delay may be split into multiple components rather than the single delay of RRC. Furthermore, the preparation and verification operations (see operations 511 and 512) may be split, for example as specified below.

[0160] LTM RRC Processing: If the UE supports the L1 / L2 triggered mobility feature (e.g., L1L2-triggered-mobility-r18), the UE RRC processing may include RRC preparation and execution of LTM-related components included in the RRC configuration message (LTM_config, see operation 510). D LTM =D LTM_preparation +D LTM_execution where: -D LTM is the total processing delay at UE 110, including LTM RRC message processing, RRC evaluation, and applying RRC configuration to L1 and L2. -T LTM_Preparation is the delay component associated with LTM preparation at UE 110. This delay may include LTM RRC message processing, RRC, and evaluation of L1 and L2 configuration. -T LTM_Execution is the delay component for setting up LTM for L1 and L2 based on the LTM switch command, which may be determined based on RRC evaluation.

[0161] LTM RRC Procedure with UL Procedure Indication: If UE 110 supports L1 / L2 triggered mobility (e.g., L1L2-triggered-mobility-r18), UE 110 may send a UL indication to the network (e.g., source DU 122-1). The UL indication indicates that UE 110 has initiated LTM preparation (T LTM_preparation ) and the execution delay T LTM_execution In this case, the network (e.g., gNB 120, e.g., source DU 122-1) may indicate that (only) LTM may be set as follows: D LTM =T LTM_Execution Alternatively, T LTM_preparation The same effect may be achieved by setting t = 0. LTM_execution ) is included, the network (e.g., source DU 122-1) may use that delay for LTM execution. For example, if the UE 110 receives and processes the RRC configuration immediately, and there is nothing to prepare afterwards (e.g., in the case of a DU), the network may use the T cmd The execution time may be determined to be equivalent to: The same delay may also be applied when UE 110 processes the RRC delta configuration and there is nothing to change. If no UL indication has been received from UE 110 (or the UL indication indicates that UE 110 cannot process the RRC reconfiguration before the cell switch command), the following delay may be applied after the cell switch command (LTM switch command): D LTM =T LTM_Preparation +T LTM_Execution

[0162] LTM Processing Order: If UE 110 supports L1 / L2 triggered mobility (e.g., L1L2-triggered-mobility-r18), UE 110 must execute LTM preparation (T) before cell switch command (LTM switch command). Preparation ) after the cell switch command, LTM execution (T LTM_Execution ) may be performed.

[0163] In operation 518, the source DU 122-1 may send a cell switch command (LTM switch command), for example, when the MAC CE is configured to trigger a cell change.

[0164] In operation 519, UE 110 may apply RRC reconfiguration (LTM_config). The RRC reconfiguration may be applied in response to receiving a cell switch command from source DU 122-1. UE 110 may, for example, perform actions remaining from the LTM evaluation of operation 512. UE 110 may, for example, configure its own hardware based on the processing of RRC (re)configuration at operation 512. UE 110 may apply the delay estimated at operation 512 and indicated to source DU 122-1, for example, at one of operations 513, 515, or 516. UE 110 may, for example, apply RRC configuration (LTM_config) within the estimated delay. Operation 519 may include all or a portion of operations 511 or 512.

[0165] Random access may be initiated between the UE 110 and the target DU 122-2 in operation 520. The UE 110 may, for example, send a random access preamble to the target DU 122-2.

[0166] At operation 521, the target DU 122-2 may send a random access (RA) response to the UE 110 in response to receiving the random access preamble at operation 520.

[0167] In operation 522, the UE 110 may send an RRC reconfiguration complete message to the target DU 122-2. The sending of the RRC reconfiguration complete message may end the handover execution phase.

[0168] In operation 523, a UE UL RRC message transfer may be performed between the target DU 122-2 and the CU 128, for example, to indicate to the CU 128 about the completion of the RRC reconfiguration at the UE 110. The UL RRC message transfer may initiate a handover completion phase.

[0169] In operation 524, the CU 128 may send a UE context release command to the source DU 122-1. The source DU 122-1 may release the UE context of the UE 110 in response to receiving this message.

[0170] In operation 525, the source DU 122-1 may send a UE context release complete message to the CU 128, for example, to notify the CU 128 about the release of the UE context of the UE 110 at the source DU 122-1.

[0171] A path switch from the source DU 122-1 to the target DU 122-2 may be performed in operation 526. For example, a data packet to be delivered to the UE 110 may be switched to be delivered to the target DU 122-2 instead of the source DU 122-1.

[0172] Four exemplary options (Options 1-4) are provided for informing the network about the processing capability / status of the RRC-LTM reconfiguration. Further, it is described that the UE 110 and the network are informed about the LTM capabilities. The following description provides further examples: - Signaling of UE capabilities for LTM processing. - Option 1: The UE sends a UL indication in the RRC Reconfiguration Complete message. - Option 2: The UE sends an LTM_UL_indication through the MAC CE (new MAC CE). - Option 3: The UE sends an LTM_UL_indication in the L1 measurement report.

[0173] FIG. 6 illustrates an example of UE capability exchange for LTM. The RRC processing capabilities of UE 110 may be indicated to the network, for example, to enable the network to follow the procedures described herein. This may be done by utilizing UE capability signaling. The signaling of this capability may be independent of or related to LTM features. For example, if UE 110 supports the LTM feature (e.g., a flag may be called L1L2TriggeredMobility-rel-18), the behavior of this capability may be specified in a standard (e.g., TS38.133). This indication may be an optional parameter and may be sent in the RRC Setup Response message or configured by the network in the RRC Setup message if UE 110 supports the LTM feature.

[0174] The UE 110 may report its own UE radio access capabilities, which may be static, for example, at least if the network so requests. The gNB may request the UE 110 to report specific capabilities based on frequency band information. The UE capabilities may be represented by a capability ID, which may be exchanged in non-access stratum (NAS) signaling over the air interface and in network signaling instead of a UE capability structure.

[0175] This capability may be signaled, for example, using a flag (e.g., L1L2-TriggeredMobility-r18) or similar, or inherently by indicating support for a standard or a version / release of that standard (e.g., Rel. 18). This capability may be signaled through UECapabilityInformation and / or UECapabilityInformation-InformationElements (IE) (RRC).

[0176] In operation 601, the CU 128 sends a UE capability inquiry, which may be sent transparently to the UE 110 by the source DU 122-1.

[0177] At operation 602, UE 110 may respond to the query (e.g., along with other capabilities) by indicating that it supports LTM (e.g., via the L1L2TriggeredMobility-r18 capability) and / or LTM RRC preprocessing (e.g., via the L1L2-TriggeredMobility-RRCPreprocessing-r18 capability).

[0178] In operation 603, the CU 128 may send the UE LTM capability information to the source DU 122-1, which may take this capability information into account in processing and scheduling decisions after a cell switch.

[0179] At 604, the CU 128, the source DU 122-1, and the UE 110 are aware of the LTM process.

[0180] An exemplary definition of UE capability signaling is presented in the following table, where M may indicate a mandatory feature, BC may indicate a band combination, FDD / TDD may indicate whether the feature is differentiated for FDD / TDD, and FR1 / FR2 may indicate whether the feature is differentiated for FR1 / FR2. N / A may indicate no expected impact. Note that, for example, if L1L2-TriggeredMobility-r18 is supported only for FR2, the feature may also be used only for FR2. This is not a technical limitation, but may be a limitation of the UE implementation.

[0181] [Table 2]

[0182] The CU 128 may be informed that the UE 110 supports LTM pre-processing based on UE capability signaling. However, the source DU 122-1 and the target DU 122-2 may not be aware of this. In order to make a cell change decision, it may be desirable to inform the source DU 122-1 whether the UE 110 supports RRC pre-processing. The CU 128 may therefore send the LTM capability information of the UE 110 to the source DU 122-1, for example as a DU configuration. The source DU 122-1 may apply this configuration assumption after MAC CE processing. This configuration may specify a UE RRC processing delay profile for applying the RRC reconfiguration (LTM_config_application).

[0183] Figure 7 shows an example of delivery of LTM capability information. First, a UE capability exchange may be performed, e.g., as described with reference to Figure 6. This may include sending an L3 report between the UE 110 and the DU.

[0184] The CU 128 may send the UE LTM capability information to the source DU 122-1.

[0185] The UE 110 may send an L3 measurement report to the source DU 122-1.

[0186] The source DU 122-1 may forward the L3 measurement report to the CU 128, for example, by transmitting a UL RRC message.

[0187] The CU 128 may make the handover decision.

[0188] Based on the UE capability information, CU 128 may create a UE delay profile for UE 110. CU 128 may take into account LTM processing for all UEs when creating the delay profile.

[0189] The CU 128 may send the UE configuration to one or more (e.g., all) candidate target cells (target DUs). Alternatively, the CU 128 may send this information to the source DU 122-1. The source DU 122-2 may send this information to the target DU before deciding to perform an LTM switch.

[0190] The remaining operations may be similar to those described with reference to Figure 5A or 5B, except that the source DU 122-1 may apply an LTM UE delay profile before deciding to change the serving cell or before sending a cell switch command.

[0191] Figures 8A and 8B show example message sequences and operations when sending an LTM uplink indication in an RRC reconfiguration complete message. The operations in these figures may be similar to the corresponding operations in Figures 5A or 5B, with the following notations:

[0192] The network may become aware of the LTM capabilities of the UE 110 after forwarding the DL message (see operation 509), e.g., through a UE capability information exchange. LTM evaluation (see operation 512) may be performed before sending the LTM_UL_indication in the RRC reconfiguration complete message. This may be referred to as option 2.1. In the ASN.1 validation, only the ASN.1 syntax may be validated. The LTM UL indication included in the RRC reconfiguration complete message may be set to indicate to the network that the UE 110 has processed the RRC configuration. This may be done, e.g., by including an optional parameter in the RRC message, e.g., L1L2TriggeredMobility-r18:rrcPreprocessing=true / yes / 1. If this parameter is set to a logical false value, it may indicate that the UE 110 was unable to perform preprocessing. This message may also include a set of parameters indicating what changes UE 110 has made (RRC reconfiguration) and / or what changes remain to be made after the LTM_switch_command, e.g., during the LTM config application operation. UE 110 may perform any actions remaining in LTM_evaluation in LTM_config_application. UE 110 may configure its own hardware based on the RRC reconfiguration. UE 110 may apply the delay indicated in the RRC reconfiguration complete message. The LTM_config application may also include all or part of the ASN.1 validation and LTM_evaluation steps.

[0193] 9A and 9B show example message sequences and operations when sending an LTM uplink indication on the MAC CE (option 2). The operations in these figures may be similar to the corresponding operations in FIG. 5A, 5B, 8A, or 8B, with the following notations: UE 110 may perform LTM evaluation either before (option 2.1) or after (option 2.2) sending the RRC reconfiguration complete message. UE 110 may send an LTM_UL_Indication on the MAC CE (see operation 515). UE 110 may indicate that it has processed the RRC configuration through a dedicated MAC CE. UE 110 may also provide information regarding how much processing delay is expected after a cell switch command. This information may be provided, for example, as an index into a mapping table that describes the processing values, for example, as follows:

[0194] [Table 3] The source DU 122-1 may apply the new delay profile of the UE based on the MAC CE.

[0195] The UE 110 may perform the remaining actions in the LTM_evaluation in the LTM_config_application. The UE 110 may configure its own hardware based on the RRC reconfiguration. The UE 110 may apply the delay indicated in the MAC CE. Alternatively, the delay may be fixed and specified, for example, in a standard. The LTM_config application may also include all or some of the steps of ASN.1 validation and LTM_evaluation.

[0196] 10A and 10B illustrate example message sequences and operations when transmitting an LTM uplink indication in the MAC CE (option 3). The operations in these figures may be similar to the corresponding operations in FIG. 5A, 5B, 8A, or 8B, with the following notations: UE 110 may perform LTM evaluation either before (option 2.1) or after (option 2.2) transmitting the RRC reconfiguration complete message. UE 110 may send an LTM_UL_Indication in an L1 measurement report (see operation 516). UE 110 may indicate that it has processed the RRC configuration through the L1 measurement report. UE 110 may also provide information regarding the expected processing delay after a cell switch command. This information may be provided, for example, as an index into a mapping table describing the processing values, e.g., as described with reference to the above options.

[0197] Alternatively, the indication through the L1 measurement report may be implicit. For example, the UE 110 may send the first L1 measurement report. The UE 110 may be configured to send the L1 report only after completing the LTM_evaluation procedure. The source DU 122-1 may determine that the UE 110 has completed the LTM evaluation based on receiving the (first) L1 measurement report. The UE 110 may, for example, have the capability to perform RRC pre-processing. If the network sets a configuration flag in the RRC config, the network may assume that the UE 110 has performed the LTM_evaluation before sending the L1 measurements.

[0198] The source DU 122-1 may take the new delay profile into account in response to receiving the LTM_UL indication in the L1 measurement report. The source DU 122-1 may, for example, apply the new delay profile to the UE based on the L1 measurement report.

[0199] In LTM_config_application, UE 110 may perform the remaining actions in LTM_evaluation. UE 110 may configure its own hardware based on the RRC reconfiguration. UE 110 may apply the delay indicated in the L1 measurement report. Alternatively, the delay may be fixed and specified, for example, in a standard. LTM_config application may also include all or some of the steps of ASN.1 validation and LTM_evaluation.

[0200] Figures 11A and 11B show example message sequences and operations when the RRC configuration indicates LTM priority (option 4). The operations in these figures may be similar to the corresponding operations in Figures 5A, 5B, 8A, or 8B, with the following notable points:

[0201] The RRC reconfiguration sent from source DU 122-1 to UE 110 may indicate that the UE is requested or instructed to incrementally process the received LTM RRC configuration, which may occur either before or after the RRC reconfiguration is complete, depending on the complexity of the configuration.

[0202] Examples of requirements for LTM are provided below: These requirements may be applicable to LTM, for example, to change an NR PCell to another NR cell or to change from an NR SCell to another SCell.

[0203] NR FRx-NR FRx LTM: This example requirement may be applicable to both intra-frequency and inter-frequency LTM from an NR FRx cell to an NR FRx cell.

[0204] LTM Delay: The procedure delay for all procedures that can command an LTM handover may be specified in the standard. The LTM delay may include or consist of an LTM preparation delay and an LTM execution delay. DLTM =D LTM_preparation +D LTM_execution

[0205] When UE 110 receives an RRC message indicating an LTM handover, UE 110 may perform an LTM preparation procedure for the LTM. The LTM RRC preparation delay may include an LTMASN.1 verification delay and an LTM RRC evaluation delay. T RRC_preparation_delay =T ASN.1_validation +T RRC_LTM_evaluation where: -T RRC_preparation_delay is the RRC pre-processing delay. This processing includes the ASN.1 verification delay and the LTM RRC configuration evaluation delay. -T ASN.1_validation ASN.1 configuration validation delay -T RRC_LTM_evaluation is the delay it takes for the UE to perform LTM configuration evaluation and extract user plane (MAC / RLC / PDCP / SDAP) and L1 processing indications from the RRC LTM command.

[0206] LTM execution time T LTM_execution is the UE execution preparation time for LTM, which may start after the UE receives the LTM switch command. T LTM_execution =T RRC_LTM_execution_intra +T LTM_switch_command where: -T RRC_execution is the delay for the UE to apply the LTM RRC configuration on L1 and L2 as indicated by the RRC command. -T LTM_switch_command is the delay in extracting and applying the target cell information from the switch command.

[0207] LTM processing requirements may be divided into intra-frequency and inter-frequency. [Table 4]

[0208] FIG. 12 shows an example of how to indicate the ability to pre-process RRC reconfiguration before a cell switch.

[0209] At 1201, the method may include receiving, by a user equipment, a radio resource control (RRC) reconfiguration message associated with a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure.

[0210] At 1202, the method may include determining whether the user equipment can pre-process at least a portion of a radio resource control reconfiguration message related to Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) prior to receiving a cell switch command to perform a cell switch.

[0211] At 1203, the method may include performing pre-processing of at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related portion of the received RRC reconfiguration message.

[0212] At 1204, the method may include, prior to receiving the cell switch command, sending a message including an indication of the preprocessed portion of the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related portion of the radio resource control reconfiguration message toward a network node of a radio access network to which the user equipment is connected.

[0213] FIG. 13 shows an example of a method for pre-processing an RRC reconfiguration.

[0214] At 1301, the method may include receiving, by a user equipment, a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure and including instructions for preprocessing at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related portion of a received RRC message.

[0215] At 1302, the method may include determining whether the user equipment can pre-process at least a portion of an indicated Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related radio resource control reconfiguration message prior to receiving a cell switch command to perform a cell switch.

[0216] At 1303, the method may include performing pre-processing of at least a portion of the received RRC message related to an indicated Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM).

[0217] FIG. 14 shows an example of a method for displaying UE functionality for pre-processing RRC reconfiguration before a cell switch.

[0218] At 1401, the method may include establishing, by a user equipment (UE), a connection to a network node of a radio access network.

[0219] At 1402, the method may include, prior to receiving a cell switch command to perform a cell switch, sending, by the UE, an indication of UE capabilities to a network node regarding the ability to support Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) operations and regarding support for pre-processing of at least a portion of a radio resource control reconfiguration message related to Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM).

[0220] At 1403, the method may include receiving, by the user equipment, a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure.

[0221] At 1404, the method may include performing pre-processing of at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related portion of the received RRC message.

[0222] FIG. 15 shows an example of how to configure the LTM delay based on an indication of the pre-processed portion of the RRC reconfiguration message for LTM.

[0223] At 1501, the method may include transmitting, by a network node of a radio access network, a radio resource control (RRC) reconfiguration message associated with a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure to a user equipment.

[0224] At 1502, the method may include receiving a message from a user equipment connected to a radio access network including an indication of a preprocessed portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related portion of a radio resource control reconfiguration message prior to receiving a cell switch command.

[0225] At 1503, the method may include configuring at least one delay value for a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure of the user equipment based on an indication of a preprocessed portion of a radio resource control reconfiguration message related to the L1 / L2 triggered mobility (LTM).

[0226] FIG. 16 illustrates a method for instructing a UE to pre-process at least some of the LTM-related portions of an RRC message.

[0227] At 1601, the method may include transmitting, by a network node to a user equipment, a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure and including instructions for preprocessing at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM)-related portion of an RRC message.

[0228] FIG. 17 illustrates a method for setting the LTM delay based on an indication of UE capability to support LTM pre-processing.

[0229] At 1701, the method may include establishing a connection with a user equipment (UE) by a network node of a radio access network.

[0230] At 1702, the method may include receiving, from the UE, an indication of UE capabilities regarding the ability to support Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedures and regarding support for pre-processing of at least a portion of a radio resource control reconfiguration message related to Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) prior to receiving a cell switch command to perform a cell switch.

[0231] At 1703, the method may include configuring at least one delay value for a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure of the user equipment based on an indication of a preprocessed portion of a radio resource control reconfiguration message related to the L1 / L2 triggered mobility (LTM).

[0232] Other features of the method result directly from the functionality of the DU 122-1, 122-2, the CU 128, or the UE 110, as described throughout the specification, claims, and drawings, and therefore will not be repeated here. An apparatus may perform or be configured to perform any aspect of the method described herein. Furthermore, a computer program or computer program product may include instructions that, when executed by an apparatus, cause the apparatus to perform any aspect of the method described herein. An apparatus may further comprise means for performing any aspect of the method described herein. According to an exemplary embodiment, the means comprises at least one processor and at least one memory that stores instructions that, when executed by the at least one processor, cause the apparatus to perform at least any aspect of the method.

[0233] Further examples of methods are provided below.

[0234] The method may include: a user equipment receiving a radio resource control configuration associated with a handover procedure; determining whether the user equipment is capable of processing the radio resource control configuration prior to receiving a cell switch command of the handover procedure; and sending to a source distributed node of the handover procedure an indication of whether the user equipment is capable of processing the radio resource control configuration prior to receiving the cell switch command.

[0235] According to an exemplary embodiment, the handover procedure comprises a layer 1 or layer 2 inter-cell mobility procedure, and the radio resource control configuration comprises a layer 1 or layer 2 mobility configuration.

[0236] According to an example embodiment, the method may include receiving a cell switch command from a source distributed node and applying a radio resource control configuration in response to receiving the cell switch command.

[0237] According to an example embodiment, the method may include estimating a delay in processing the radio resource control configuration and transmitting an indication of the estimated delay in processing the radio resource control configuration to the source distributed node.

[0238] According to an example embodiment, the method may include receiving a cell change command from a source distributed node and applying radio resource control settings within the estimated delay.

[0239] According to an example embodiment, determining whether the user equipment is capable of processing the radio resource control configuration before receiving the cell switch command or before estimating the delay for processing the radio resource control configuration includes at least one of determining at least one change required for the media access control configuration, determining at least one change required for the radio link control configuration, determining at least one change required for the packet data convergence protocol configuration, determining at least one change required for the service data adaptation protocol configuration, determining whether a radio frequency readjustment is required to comply with the cell switch command, determining whether a baseband readjustment is required to comply with the cell switch command, or determining whether the user equipment can access the target access node unit of the handover procedure without a random access channel procedure.

[0240] According to an example embodiment, the method may include transmitting an indication of completion of processing of the radio resource control configuration by the user equipment to the source distributed node.

[0241] According to an exemplary embodiment, the completion indication of the radio resource control configuration process is sent in a radio resource control reconfiguration complete message, in a media access control control element, in a Layer 1 measurement report or as an indication of user equipment capabilities.

[0242] According to an exemplary embodiment, the user equipment function includes: the user equipment is configured to perform a validation of a syntax notation of the radio resource control configuration; a determination of whether the user equipment is able to process the radio resource control configuration before receiving a cell switch command or an estimation of a delay for processing the radio resource control configuration is made in response to receiving the radio resource control configuration from the source distributed node; the user equipment is configured to perform a validation of a syntax notation of the radio resource control configuration in response to receiving the radio resource control configuration from the source distributed node; the user equipment is configured to perform a validation of a syntax notation of the radio resource control configuration; the user equipment is configured to process the radio resource control configuration before initiating Layer 1 measurements for the handover procedure; the user equipment is configured to process the radio resource control configuration after initiating Layer 1 measurements for the handover procedure; or the user equipment is configured to initiate, in response to receiving an indication of a target cell for the handover procedure from the source distributed node, determining whether the user equipment can process the radio resource control configuration before receiving a cell switch command or estimating a delay for processing the radio resource control configuration.

[0243] According to an example embodiment, the method may include the user equipment determining whether it can process the radio resource control configuration prior to receiving a cell switch command or estimating a delay in processing the radio resource control configuration in response to receiving a request from a source distributed node to prioritize verification, processing, or preparation of the radio resource control configuration.

[0244] The method may include the access node sending a radio resource control configuration associated with the handover procedure to the user equipment; receiving an indication from the user equipment of whether the user equipment is capable of processing the radio resource control configuration prior to receiving a cell switch command; setting at least one delay value for the handover procedure based on the indication of whether the user equipment is capable of processing the radio resource control configuration prior to receiving the cell switch command; and sending a cell switch command for the handover procedure to the user equipment.

[0245] According to an exemplary embodiment, the handover procedure comprises a layer 1 or layer 2 inter-cell mobility procedure, and the radio resource control configuration comprises a layer 1 or layer 2 mobility configuration.

[0246] According to an example embodiment, the method may include receiving, from the user equipment, an indication of an estimated delay for processing the radio resource control configuration by the user equipment, and setting at least one delay value for the handover procedure based on the estimated delay for processing the radio resource control configuration by the user equipment.

[0247] According to an example embodiment, the method may include receiving, from the user equipment, an indication of completion of processing of the radio resource control configuration by the user equipment, and setting at least one delay value of the handover procedure based on the indication of completion of processing of the radio resource control configuration by the user equipment.

[0248] According to an exemplary embodiment, the indication of completion of the radio resource control configuration process is received in a radio resource control reconfiguration complete message, in a media access control control element, in a Layer 1 measurement report or as an indication of user equipment capabilities.

[0249] According to an exemplary embodiment, the user equipment function includes: the user equipment is configured to perform a syntax validation of the radio resource control configuration, and a determination of whether the user equipment is able to process the radio resource control configuration prior to receiving a cell switch command or an estimation of a delay for processing the radio resource control configuration is made in response to receiving the radio resource control configuration from the source distribution node of the access node; the user equipment is configured to perform a syntax validation of the radio resource control configuration in response to receiving the radio resource control configuration from the source distribution node of the access node; the user equipment is configured to transmit a Layer 1 measurement report including an indication of whether the user equipment is able to process the radio resource control configuration prior to receiving a cell switch command; the user equipment is configured to process the radio resource control configuration before initiating Layer 1 measurements for the handover procedure; the user equipment is configured to process the radio resource control configuration after initiating Layer 1 measurements for the handover procedure; or the user equipment is configured to initiate, in response to receiving an indication of a target cell for the handover procedure from the source distribution node of the access node, before receiving the cell switch command, determining whether the user equipment can process the radio resource control configuration or estimating the delay required to process the radio resource control configuration.

[0250] According to an example embodiment, the method may include transmitting a request to a user equipment to prioritize verification, processing, or preparation of radio resource control configuration.

[0251] Any ranges or device values ​​set forth herein may be expanded or modified without losing the desired effect, and any embodiment may be combined with another embodiment unless expressly prohibited.

[0252] Although the subject matter has been described in language specific to structural features and / or acts, it should be understood that the subject matter 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 ways of implementing the claims, and other equivalent features and acts are intended to be within the scope of the claims.

[0253] It will be understood that the benefits and advantages described above may relate to one embodiment or to several embodiments. The embodiments are not limited to those that solve any or all of the described problems or that have any or all of the described benefits and advantages. It will be further understood that reference to "an" or "an" item may refer to one or more of such items.

[0254] The steps or actions of the methods described herein may be performed in any suitable order, or simultaneously where appropriate. Further, individual blocks may be deleted from any of the methods without departing from the scope of the subject matter described herein. Aspects of any of the exemplary embodiments described above may be combined with aspects of any of the other exemplary embodiments described to form further exemplary embodiments without losing the desired effect.

[0255] The term "comprising" is used herein to mean that, while specified methods, blocks, or elements are included, such blocks or elements do not constitute an exclusive list and that a method or apparatus may include additional blocks or elements.

[0256] As used herein, "at least one of: " and "at least one of " and similar phrases where a list of two or more elements is joined by "and" or "or" mean at least any one of the elements, at least any two or more of the elements, or at least all of the elements.

[0257] Although an object may be referred to as a "first" object or a "second" object, this does not necessarily indicate the order or importance of the objects. Instead, such conjunctions may be used only to distinguish between the objects.

[0258] The term "circuitry," as used in this application, may refer to one or more, or all, of: (a) hardware-only circuit implementations (such as implementations with only analog and / or digital circuitry); (b) combinations of hardware circuitry and software (where applicable): (i) combinations of analog and / or digital hardware circuitry with software / firmware; (ii) any portion of a hardware processor (including a digital signal processor) along with software, software, and memory, etc., that work together to cause a device such as a cell phone or server to perform various functions; and (c) hardware circuits and / or processors, such as a microprocessor or portion of a microprocessor, that require software (e.g., firmware) to operate but may be absent when not necessary for operation. This definition of circuitry applies to all uses of the term in this application, including all claims.

[0259] As a further example, the term circuitry as used in this application covers implementations solely of a hardware circuit or processor(s), or of portions of a hardware circuit or processor, and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example, baseband or processor integrated circuits for mobile devices, or similar integrated circuits in servers, cellular network devices, or other computing or network devices, where applicable to certain claimed elements.

[0260] It will be understood that the above description is provided by way of example only, and that various modifications may be made by those skilled in the art. The above specification, examples, and data provide a complete description of the structure and use of the exemplary embodiments. Although various embodiments have been described above with a degree of particularity, or with reference to one or more individual embodiments, those skilled in the art may make numerous modifications to the disclosed embodiments without departing from the scope of this specification.

Claims

1. receiving, by a user equipment, a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure; determining whether the user equipment is capable of pre-processing at least a portion of the radio resource control reconfiguration message for Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) prior to receiving a cell switch command to perform a cell switch; performing pre-processing of at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related portion of the received RRC reconfiguration message; sending a message including an indication of the pre-processed portion of the Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) related portion of the radio resource control reconfiguration message towards a network node of a radio access network to which the user equipment is connected before the reception of the cell switch command; A method comprising:

2. 2. The method of claim 1, wherein the network node is an aggregation node of the radio access network, and the message sent to the aggregation node is an RRC reconfiguration complete message including an LTM indication indicating a status of the pre-processing of LTM preparation operations, in particular an indication of whether at least one of operations related to Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation has been performed.

3. 2. The apparatus of claim 1, wherein the network node is a distributed node of the radio access network, and the message transmitted to the distributed node is a medium access control (MAC) control element (CE) message including an L2 message, in particular an LTM indication indicating the status of the pre-processing of an LTM preparation operation, in particular an indication of whether at least one of an operation related to Abstract Syntax Notation One (ASN.1) validation and an LTM RRC configuration evaluation has been performed.

4. 2. The apparatus of claim 1, wherein the network node is a distributed node of the radio access network, and the message sent to the distributed node is an L1 Measurement Report message including an LTM indication indicating a status of the pre-processing of LTM preparation operations, in particular an indication of whether at least one of operations related to Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation has been performed.

5. The method of any one of claims 1 to 4, wherein the indication for the preprocessed portion includes an indication for the remaining LTM execution time delay.

6. receiving, by a user equipment, a Radio Resource Control (RRC) Reconfiguration message associated with a Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) procedure, the RRC Reconfiguration message including instructions for pre-processing at least a portion of a received RRC message related to Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM); determining whether the user equipment is capable of pre-processing at least a portion of the indicated radio resource control reconfiguration message related to Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) prior to receiving a cell switch command to perform a cell switch; and performing pre-processing of at least a portion of the indicated portion of the received RRC message related to the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM); A method comprising:

7. sending an L1 measurement report message towards a network node of a radio access network to which the user equipment is connected after the performed pre-processing is completed. The method of any one of claims 1 to 6, further comprising:

8. In response to receiving an L2 message, in particular a MAC CE message, including the cell switch command, processing a non-preprocessed Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related portion of the received RRC reconfiguration message, extracting information of a target cell to switch to from the cell switch command, and performing a random access procedure towards the target cell. The method of any one of claims 1 to 7, further comprising:

9. Establishing a connection by a user equipment (UE) to a network node of a radio access network; sending, by the UE, an indication of UE capabilities towards the network node regarding the ability to support Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) operations and regarding support for pre-processing of at least a portion of a Radio Resource Control Reconfiguration message related to Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) prior to receiving a cell switch command to perform a cell switch; receiving, by the user equipment, a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure; performing pre-processing of at least a portion of the received RRC message related to Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM); A method comprising:

10. 10. The method of claim 9, wherein the indication of UE capabilities is sent to the network node during or after establishment of the connection to the network node.

11. 11. The method of claim 10, wherein the indication of UE capabilities is sent to the network node before performing LTM preparation, or the indication of UE capabilities is sent to the network node before or together with an L3 measurement report.

12. 12. The method of claim 1, wherein the pre-processing of the at least a portion of the Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) related portion of the received RRC reconfiguration message comprises pre-processing at least one of Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation related operations.

13. sending, by a network node of a radio access network, a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure to a user equipment; receiving, from a user equipment connected to the radio access network, a message including an indication of a pre-processed portion of the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related portion of the radio resource control reconfiguration message prior to receipt of a cell switch command; configuring at least one delay value for the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure of the user equipment based on the indication of the preprocessed portion of the L1 / L2 triggered mobility (LTM) related portion of the radio resource control reconfiguration message by the user equipment; A method comprising:

14. 14. The method of claim 13, wherein the network node is an aggregation node of the radio access network, and the message received by the aggregation node is an RRC reconfiguration complete message including an LTM indication indicating a status of the pre-processing of LTM preparation operations, in particular an indication of whether at least one of operations related to Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation has been performed.

15. 14. The apparatus of claim 13, wherein the network node is a distributed node of the radio access network, and the message received by the distributed node is a medium access control (MAC) control element (CE) message including an L2 message, in particular an LTM indication indicating the status of the pre-processing of an LTM preparation operation, in particular an indication of whether at least one of an operation related to Abstract Syntax Notation One (ASN.1) validation and an LTM RRC configuration evaluation has been performed.

16. 14. The apparatus of claim 13, wherein the network node is a distributed node of the radio access network, and the message received by the distributed node is an L1 Measurement Report message including an LTM indication indicating a status of the pre-processing of LTM preparation operations, in particular an indication of whether at least one of operations related to Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation has been performed.

17. The method of any one of claims 13 to 16, wherein the indication for the preprocessed portion includes an indication for the remaining LTM execution time delay.

18. transmitting, by a network node to a user equipment, a Radio Resource Control (RRC) reconfiguration message associated with a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure, the RRC reconfiguration message including instructions for pre-processing at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related portion of an RRC message; A method comprising:

19. establishing a connection with a user equipment (UE) by a network node of a radio access network; receiving, from the UE, an indication of UE capabilities regarding the ability to support Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedures and regarding support for pre-processing of at least a portion of a radio resource control reconfiguration message related to Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) prior to receiving a cell switch command to perform a cell switch; configuring at least one delay value for the Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure of the user equipment based on an indication of the preprocessed portion of the L1 / L2 triggered mobility (LTM) related portion of the radio resource control reconfiguration message by the user equipment; A method comprising:

20. 20. The method of claim 19, wherein the indication of UE capabilities is received during or after establishment of the connection with the UE.

21. 21. The method of claim 20, wherein the indication of UE capabilities is received before or together with an L3 measurement report.

22. 20. The method of claim 13, wherein the pre-processing of the at least some of the Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) related portions of the received RRC reconfiguration message comprises pre-processing at least one of Abstract Syntax Notation One (ASN.1) validation and LTM RRC configuration evaluation related operations.

23. Apparatus comprising means for carrying out the method of any one of claims 1 to 22.

24. A computer program comprising instructions which, when executed by an apparatus, cause the apparatus to carry out the method of any one of claims 1 to 22.

25. A user equipment, UE, at least one processor; When executed by the at least one processor, the UE receives at least: receiving, by a user equipment, a radio resource control (RRC) reconfiguration message related to a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure; determining whether the user equipment is capable of pre-processing at least a portion of the radio resource control reconfiguration message for Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) prior to receiving a cell switch command to perform a cell switch; performing pre-processing of at least a portion of a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) related portion of the received RRC reconfiguration message; sending a message including an indication of the pre-processed portion of the Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) related portion of the radio resource control reconfiguration message towards a network node of a radio access network to which the user equipment is connected before the reception of the cell switch command; at least one memory storing instructions for causing the A UE comprising:

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