Indication of capability of handling radio resource control configuration for handover

Abstract

Various example embodiments relate to cell handover in a cellular communication network. Receiving, by the user equipment, a radio resource control (RRC) reconfiguration message associated with a Layer 1 / Layer 2 (L1 / L2) triggered mobility (LTM) procedure; determining whether the UE is capable of pre-processing at least a portion of an RRC reconfiguration message related to the LTM prior to reception of a cell handover command for performing a cell handover; pre-processing of at least a portion of the LTM-related portion of the received RRC reconfiguration message is performed, and a message is sent towards a network node of a radio access network to which the user equipment is connected, the message comprising an indication related to the pre-processed portion of the LTM-related portion of the radio resource control reconfiguration message prior to reception of the cell handover command.

Description

Technical Field

[0001] Various example embodiments generally relate to the field of cellular communication networks. Some example embodiments relate to an indication of the ability to signal to a user equipment to process a radio resource control configuration for handover. Background Art

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

[0003] This Summary of the Invention is provided to introduce a series of concepts in a simplified form that will be further described in the Detailed Description below. This Summary of the Invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0004] Example embodiments of the present disclosure enable a reduction in handover or cell change latency. This benefit and other benefits can be achieved by the features of the independent claims. Additional example embodiments are provided in the dependent claims, the description, and the drawings.

[0005] According to a first aspect, a method is disclosed. 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; determining whether the user equipment is capable of preprocessing at least a portion of the radio resource control reconfiguration message related to a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) before receiving a cell change command for performing a cell handover; performing preprocessing of at least a portion of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the received RRC reconfiguration message; and sending a message to a network node of a radio access network to which the user equipment is connected, the message including: an indication related to a preprocessing portion of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the radio resource control reconfiguration message before receiving a cell change command.

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

[0007] According to an example 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 example embodiment of the first aspect, the L2 message includes a Media Access Control (MAC) Control Element (CE) message, and the L2 message includes an LTM indication indicating the status of preprocessing for the LTM preparation operation.

[0009] According to an example 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, and the L1 measurement report message includes: an LTM indication indicating the status of preprocessing for the LTM preparation operation.

[0010] According to an example embodiment of the second aspect, the LTM indication indicating the status of preprocessing for the LTM preparation operation includes an indication of whether at least one of the following has been performed: Abstract Syntax Notation One (ASN.1) verification and operations related to LTM RRC configuration evaluation.

[0011] According to an example embodiment of the second aspect, the indication related to the preprocessing part includes: an indication related to the remaining LTM execution time delay.

[0012] According to the second aspect, a method is disclosed. 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, the RRC reconfiguration message including: an instruction to preprocess at least a part of the received RRC message related to the Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM); determining whether the user equipment is capable of preprocessing at least a part of the indicated Radio Resource Control reconfiguration message related to the Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) before receiving a cell handover command for performing a cell handover; and performing preprocessing of at least a part of the indicated Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) related part of the received RRC message.

[0013] According to an example embodiment of the second aspect, the method may include: after the performed preprocessing ends, sending an L1 measurement report message to a network node of the radio access network to which the user equipment is connected.

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

[0015] According to an example embodiment of the second aspect, the L2 message includes a media access control (MAC) control element (CE) message.

[0016] According to a third aspect, a method is disclosed: The method may include: establishing, by a user equipment (UE), a connection towards a network node of a radio access network; sending, by the UE towards the network node, a UE capability indication related to the ability to support layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) operations and related to the support of preprocessing of at least a part of a radio resource control reconfiguration message related to layer 1 / layer 2 (L1 / L2) triggered mobility (LTE) before receiving a cell handover command for performing a cell handover; receiving, by the user equipment, a radio resource control (RRC) reconfiguration message associated with a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) process; and performing preprocessing of at least a part of a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the received RRC message.

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

[0018] According to an example embodiment of the third aspect, the UE capability indication is sent to the network node before performing preparations for LTM, or, wherein the UE capability indication is sent to the network node before or together with an L3 measurement report.

[0019] According to an example embodiment of the third aspect, preprocessing of at least a part of a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the received RRC reconfiguration message includes preprocessing of at least one of the following: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

[0020] According to a fourth aspect, a method is disclosed. The method may include: sending, 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) process to a user equipment; receiving, from the user equipment connected to the radio access network, a message that includes: an indication related to a preprocessing part of the L1 / L2 triggered mobility (LTM) related part of the RRC reconfiguration message before receiving a cell handover command; and configuring, based on the indication related to the preprocessing part of the L1 / L2 triggered mobility (LTM) related part of the RRC reconfiguration message made by the user equipment, at least one delay value of the L1 / L2 triggered mobility (LTM) process for the user equipment.

[0021] According to an example embodiment of the fourth aspect, the network node is a central node of the radio access network, and the message received by the central node is an RRC reconfiguration complete message, and the RRC reconfiguration complete message includes: an LTM indication indicating a status of preprocessing of an LTM preparation operation.

[0022] According to an example embodiment of the fourth aspect, the network node is a distributed node of the radio access network, and the message received by the distributed node is an L2 message, and the L2 message includes: an LTM indication indicating a status of preprocessing of an LTM preparation operation.

[0023] According to an example embodiment of the fourth aspect, the L2 message includes a media access control (MAC) control element (CE) message.

[0024] According to an example embodiment of the fourth aspect, 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, and the L1 measurement report message includes: an LTM indication indicating a status of preprocessing of an LTM preparation operation.

[0025] According to an example embodiment of the fourth aspect, the LTM indication indicating a status of preprocessing of an LTM preparation operation includes an indication of whether at least one of the following has been performed: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

[0026] According to an example embodiment of the fourth aspect, the indication related to the preprocessing part includes: an indication related to a remaining LTM execution time delay.

[0027] According to a fifth aspect, a method is disclosed. The method may include: a network node sending a radio resource control (RRC) reconfiguration message associated with a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) process to a user equipment, the RRC reconfiguration message including: an instruction for preprocessing at least a part of a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the pre-RRC message.

[0028] According to a sixth aspect, a method is disclosed. The method may include: a network node of a radio access network establishing a connection with a user equipment (UE); receiving a UE capability indication from the UE, the UE capability indication being related to the capability of supporting a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) process and being related to the support for preprocessing at least a part of a radio resource control reconfiguration message related to a layer 1 / layer 2 (L1 / L2) triggered mobility (LTE) before receiving a cell handover command for performing a cell handover; and configuring at least one delay value for the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) process for the user equipment based on an indication related to a preprocessing part of a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the radio resource control reconfiguration message performed by the user equipment.

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

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

[0031] According to an example embodiment of any one of the first aspect to the sixth aspect, the preprocessing of at least a part of a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the received RRC reconfiguration message includes preprocessing at least one of the following: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

[0032] According to a seventh aspect, a device is disclosed. The device may include components for performing the method according to any one of the first aspect to the sixth aspect or any of its example embodiments.

[0033] According to an eighth aspect, a computer program or a computer program product is disclosed. The computer program or the computer program product may include instructions that, when executed by a device, cause the device to perform the method according to any one of the first aspect to the sixth aspect or any of its example embodiments.

[0034] According to a ninth aspect, an apparatus is disclosed. The apparatus may include at least one processor; and at least one memory storing 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; determine whether the user equipment is capable of preprocessing at least a portion of the radio resource control reconfiguration message related to layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) before receiving a cell handover command for performing a cell handover; perform preprocessing of at least a portion of the L1 / L2 triggered mobility (LTM) related portion of the received RRC reconfiguration message; and send a message towards a network node of a radio access network to which the user equipment is connected, the message including: an indication related to a preprocessing portion of the L1 / L2 triggered mobility (LTM) related portion of the radio resource control reconfiguration message before receiving a cell handover command.

[0035] According to an example embodiment of the ninth aspect, the network node is a central node of the radio access network, and the message sent to the central node is an RRC reconfiguration complete message, the RRC reconfiguration complete message including: an LTM indication indicating a status of preprocessing of the LTM preparation operation.

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

[0037] According to an example embodiment of the ninth aspect, the L2 message includes: a media access control (MAC) control element (CE) message, the message including an LTM indication indicating a status of preprocessing of the LTM preparation operation.

[0038] According to an example embodiment of the ninth aspect, 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, the L1 measurement report message including: an LTM indication indicating a status of preprocessing of the LTM preparation operation.

[0039] According to an example embodiment of the ninth aspect, the LTM indication indicating a status of preprocessing of the LTM preparation operation includes an indication of whether at least one of the following has been performed: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

[0040] According to an example embodiment of the ninth aspect, the indication related to the preprocessing portion includes: an indication related to a remaining LTM execution time delay.

[0041] According to a tenth aspect, a device is disclosed. The device may include at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the device 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, the RRC reconfiguration message including: instructions for preprocessing at least a part of an L1 / L2 triggered mobility (LTM)-related part of the received RRC message; determine whether the user equipment is capable of preprocessing at least a part indicated by the radio resource control reconfiguration message related to L1 / L2 triggered mobility (LTM) before receiving a cell handover command for performing a cell handover; and perform preprocessing of at least a part of the indicated L1 / L2 triggered mobility (LTM)-related part of the received RRC message.

[0042] According to an example embodiment of the tenth aspect, the instructions are configured to, when executed by the at least one processor, cause the device to: after the completion of the performed preprocessing, send an L1 measurement report message to a network node of a radio access network to which the user equipment is connected.

[0043] According to an example embodiment of the tenth aspect, the instructions are configured to, when executed by the at least one processor, cause the device to: in response to receiving an L2 message including a cell handover command, process a non-preprocessed L1 / L2 triggered mobility (LTM)-related part of the received RRC reconfiguration message, extract target cell information to be handed over from the cell handover command, and perform a random access procedure towards the target cell.

[0044] According to an example embodiment of the tenth aspect, the L2 message includes: a media access control (MAC) control element (CE) message.

[0045] According to the eleventh aspect, a device is disclosed. The device may include at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the device to at least: establish a connection towards a network node of a radio access network by a user equipment (UE); send, by the UE towards the network node, a UE capability indication that is related to the ability to support layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) operations and that is related to the support of preprocessing of at least a part of a radio resource control reconfiguration message that is related to layer 1 / layer 2 (L1 / L2) triggered mobility (LTE) prior to the reception of a cell handover command for performing a cell handover; receive, by the user equipment, a radio resource control (RRC) reconfiguration message associated with a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) procedure; and perform preprocessing of at least a part of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM)-related part of the received RRC message.

[0046] According to an example embodiment of the eleventh aspect, the instructions are configured to, when executed by the at least one processor, cause the device to: send the UE capability indication to the network node during or after the establishment of the connection to the network node.

[0047] According to an example embodiment of the eleventh aspect, the instructions are configured to, when executed by the at least one processor, cause the device to: send the UE capability indication to the network node before performing preparations for LTM, or the UE capability indication is sent to the network node before or together with an L3 measurement report.

[0048] According to an example embodiment of the eleventh aspect, the preprocessing of at least a part of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM)-related part of the received RRC reconfiguration message includes preprocessing of at least one of the following: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

[0049] According to a twelfth aspect, an apparatus is disclosed. The apparatus may include at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to at least: send, 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) process to a user equipment; receive, from the user equipment connected to the radio access network, a message that includes: an indication related to a preprocessing part of a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the RRC reconfiguration message prior to receipt of a cell handover command; and configure, based on the indication related to the preprocessing part of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the RRC reconfiguration message made by the user equipment, at least one delay value for the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) process for the user equipment.

[0050] According to an example embodiment of the twelfth aspect, the network node is a central node of the radio access network, and the message received by the central node is an RRC reconfiguration complete message, the RRC reconfiguration complete message including: an LTM indication indicating a status of preprocessing of an LTM preparation operation.

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

[0052] According to an example embodiment of the twelfth aspect, the L2 message includes a media access control (MAC) control element (CE) message.

[0053] According to an example embodiment of the twelfth aspect, 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, the L1 measurement report message including: an LTM indication indicating a status of preprocessing of an LTM preparation operation.

[0054] According to an example embodiment of the twelfth aspect, the LTM indication indicating a status of preprocessing of an LTM preparation operation includes an indication of whether at least one of the following has been performed: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

[0055] According to an example embodiment of the twelfth aspect, the indication related to the preprocessing part includes: an indication related to a remaining LTM execution time delay.

[0056] According to a thirteenth aspect, an apparatus is disclosed. The apparatus may include at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: send, by a network node, a radio resource control (RRC) reconfiguration message associated with a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) process to a user equipment, the RRC reconfiguration message including: instructions for preprocessing at least a part of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the pre-RRC message.

[0057] According to a fourteenth aspect, an apparatus is disclosed. The apparatus may include at least one processor; and at least one memory storing 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 a UE capability indication from the UE, the UE capability indication being related to the ability to support a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) process and being related to the support for preprocessing at least a part of a radio resource control reconfiguration message related to a layer 1 / layer 2 (L1 / L2) triggered mobility (LTE) before receiving a cell handover command for performing a cell handover; and configure, based on an indication related to a preprocessing part of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the radio resource control reconfiguration message performed by the user equipment, at least one delay value for the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) process for the user equipment.

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

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

[0060] According to an example embodiment of any one of the ninth to fourteenth aspects, the preprocessing of at least a part of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the received RRC reconfiguration message includes preprocessing of at least one of the following: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

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

[0062] Accordingly, example embodiments of the present disclosure can provide an apparatus, method, computer program, computer program product, or computer-readable medium for implementing handover or cell handover with short latency. Any example embodiment can be combined with one or more other example embodiments. These and other aspects of the present disclosure will be apparent from the (multiple) example embodiments described below. According to some aspects, the subject matter of the independent claims is provided. Some additional aspects are defined in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0064] Figure 1 An example of a communication network is illustrated;

[0065] Figure 2 An example of components of a 5G New Radio (NR) network topology is illustrated;

[0066] Figure 3 An example of an apparatus configured to practice one or more example embodiments is illustrated;

[0067] Figure 4 An example of the latency associated with a Layer 3 (L3) handover procedure is illustrated;

[0068] Figure 5A and Figure 5B An example of a message sequence and operations for L1 / L2-triggered mobility is illustrated;

[0069] Figure 6 An example of UE capability exchange for LTM is illustrated;

[0070] Figure 7A and Figure 7B An example of the delivery of LTM capability information is illustrated;

[0071] Figure 8A and Figure 8B An example of a message sequence and operations when sending an LTM uplink indication in an RRC reconfiguration complete message is illustrated;

[0072] Figure 9A and Figure 9B An example of a message sequence and operations when sending an LTM uplink indication in a Media Access Control (MAC) control element (CE) is illustrated;

[0073] Figure 10A and Figure 10BIllustrates an example of a message sequence and operations when sending an LTM uplink indication in a MAC CE;

[0074] Figure 11A and Figure 11B Illustrates an example of a message sequence and operations when an RRC configuration indicates LTM priority;

[0075] Figure 12 Illustrates an example of a method for indicating the ability to preprocess an RRC reconfiguration before a cell handover;

[0076] Figure 13 Illustrates an example of a method for preprocessing an RRC reconfiguration;

[0077] Figure 14 Illustrates an example of a method for indicating the ability of a UE to preprocess an RRC reconfiguration before a cell handover;

[0078] Figure 15 Illustrates an example of a method for configuring (multiple) LTM delays based on an indication related to a preprocessing part of an RRC reconfiguration message related to LTM;

[0079] Figure 16 Illustrates a method for instructing at least a part of an LTM-related part of an RRC message to be preprocessed by a UE; and

[0080] Figure 17 Illustrates a method for configuring (multiple) LTM delays based on an indication of the ability of a UE to support LTM preprocessing.

[0081] In the drawings, the same reference numerals are used to denote the same components. Detailed Description

[0082] Now, reference will be made in detail to example embodiments, examples of which are illustrated in the drawings. The detailed description provided below in conjunction with the drawings is intended as a description of the present example and is not intended to represent the only form in which the present example can be constructed or used. The description sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences can be achieved by different examples.

[0083] A UE can be connected to different cells of a network and perform a mobility (handover) process between cells using L1 and / or L2 signaling, such as in-DU (distributed unit or distributed node) or inter-DU cell handover 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) can trigger a cell handover. L1 measurements can be used during the execution phase of a cell handover. Such a process can be referred to as L1 / L2 mobility. Example embodiments of the present disclosure can provide mechanisms and processes for L1 / L2-based inter-cell mobility that enable reduction of latency in L1 / L2-triggered mobility (LTM), enable configuration and maintenance of multiple candidate cells to allow for fast application of configurations for candidate cells, provide a dynamic handover mechanism between candidate serving cells (including special cell SpCell and secondary cell SCell) for applicable scenarios based on L1 / L2 signaling, provide L1 enhancements for inter-cell beam management (e.g., including L1 measurements and reports and / or beam indication), and implement timing advance management, and provide central unit (CU) / distributed unit (DU) interface signaling to support LTM. Reference Figure 1 Describe the distribution of processing of an access node to a CU and one or more DUs. The described L1 / L2-based inter-cell mobility process can be applicable to the following scenarios:

[0084] - Having a serving cell change within a single configuration grant (CG), carrier aggregation (CA), or 5G new radio (NR) dual connectivity (NR-DC),

[0085] - In-DU cases and inter-DU cases within a CU (applicable to both stand-alone and CA),

[0086] - Both intra-frequency and inter-frequency mobility,

[0087] - Both frequency range 1 (FR1) and frequency range 2 (FR2), or

[0088] - Source and target cells being synchronized or not synchronized.

[0089] For example, in the above scenario, example embodiments of the present disclosure enable reduction of handover (inter-cell mobility) latency. In Layer 1 / Layer 2 Triggered Mobility (LTM), the UE can be configured to report Layer 1 beam measurements to the serving DU (source DU). Based on the Layer 1 beam measurements, the serving DU can decide when to trigger a handover. This enables simplification of many network and UE mobility procedures and reduction of interruption time or latency caused by mobility. In addition, network data forwarding and scheduling can also benefit from LTM. In LTM, the UE can maintain configurations of multiple cells to enable rapid application of each configuration. LTM can involve or not involve a serving cell change, and it can use the Random Access Channel (RACH) or be RACH-free.

[0090] In LTM, the serving DU can trigger execution of a prepared target cell configuration based on lower layer (Layer 1 / Layer 2) signaling, which can include, for example, a Media Access Control (MAC) Control Element (CE) or Downlink Control Information (DCI). After triggering a cell change, the serving DU can notify the CU, which can terminate sending any RRC reconfiguration messages over the serving cell radio link and initiate data forwarding to the target cell.

[0091] LTM can use Layer 1 measurements. The benefit of these measurements is a faster reaction time to radio link degradation in the serving link, for example, because the network can save the latency due to Layer 3 (L3) filtering and the trigger time to trigger (TTT) latency of the handover decision. This can reduce the number of radio link failures compared to non-Layer 1 / Layer 2-based handovers.

[0092] Figure 1 An example of a split access node architecture is illustrated. The access node, represented throughout the description by gNB 120, can be functionally and / or physically split into a Central Unit (CU) 128 and one or more Distributed Units (DUs), in this example two DUs 122-1 and 122-2. The CU 128 can also be referred to as gNB-CU, and the (multiple) DUs can also be referred to as (multiple) gNB-DUs. The CU 128 can include a Control Plane (CP) and a User Plane (UP) entity represented by gNB-CU-CP 124 and gNB-CU-UP 126, respectively. The gNB-CU-CP 124 can be configured to control the communication of signaling data that enables the transmission of user / application data at the user plane. User plane communication can be provided by one or more gNB-CU-UP 126 associated with the gNB-CU-CP 124. The CU 128 and the (multiple) DUs 122-1, 122-2 can be configured to provide Radio Access Network (RAN) services to the (multiple) devices represented by User Equipment (UE) 110 at one or more cells 112.

[0093] The control and user plane entities of CU 128 can communicate via a communication interface (such as, for example, an E1 interface). CU 128 can communicate with DU via a communication interface (such as, for example, an F1 interface). The F1 interface can include a control plane interface and a user plane interface (F1-C, F1-U) between the control plane entity and the user plane entity of DU and CU 128 respectively. Although Figure 1 two DUs are shown, CU can generally be associated with one or more DUs.

[0094] The CU / DU split architecture enables the decomposition of the RAN, enabling the operator to use different suppliers for different network nodes and also enabling the network supplier to split its network implementation for scalability purposes. For example, the control plane and the user plane can be separated into their own entities, enabling the sizing of the control plane function and the user plane function to be determined separately. However, this split can be (almost) invisible to the user equipment (UE), and thus, on the UE side, the protocol layer can (mostly) be unaware of the split, except for a minor part that the UE can implicitly determine from the associated radio resource control RRC configuration. In the case of handover within or between DUs, the network can be configured to explicitly control which part of the protocol stack is reconfigured. This can be included in the RRC processing, and thus the RRC latency can be variable or static, but with different latencies for different scenarios.

[0095] UE 110 can access application services via the RAN, which can include one or more gNBs 120. UE 110 can communicate with gNB 120 via a radio interface, which is configured, for example, based on the 5G NR (New Radio) standard defined by the 3rd Generation Partnership Project (3GPP). Thus, the communication network 100 can include a wireless communication network.

[0096] The communication network 100 can operate based on a protocol stack including multiple protocol layers. The protocol stack can be arranged based on the Open Systems Interconnection (OSI) model or a layer model of a specific standard (such as, for example, a 3GPP standard). In one example, the protocol stack can include a service data adaptation protocol (SDAP) layer, which can receive data from the application layer for transmission. The SDAP layer can be configured to exchange data with the packet data convergence (PDCP) layer. The PDCP layer can be responsible for generating, for example, a data burst including one or more data packets based on the data obtained from the SDAP layer.

[0097] The PDCP layer can provide data to one or more instances of the radio link control (RLC) layer. For example, PDCP data can be sent on one or more RLC transport branches. Each RLC instance can be associated with a corresponding MAC instance of the MAC layer (layer 2). The MAC layer can provide a mapping between the logical channels of the (multiple) upper layers and the transport channels of the physical layer, and handle the multiplexing and demultiplexing of MAC service data units (SDUs). In addition, the MAC layer can provide an error correction function based on packet retransmission, such as according to the hybrid automatic repeat request (HARQ) process. Physically independent transport branches can be provided by the physical (PHY) layer (also known as layer 1 (L1)). The RLC, MAC, and L1 functions can reside on the (multiple) DUs 122-1, 122-2. The corresponding protocol stack can be applied at both the gNB 120 and the UE 110.

[0098] In a split access node architecture, a part of the protocol layer can be implemented at the CU 128. In Figure 1 the example, the CU 128 (e.g., CU-UP 126) can be configured to handle the upper layers of the protocol stack, such as the SDAP and PDCP layers. In addition, the CU 128 (e.g., CU-CP 124) can be configured to handle radio resource control (RRC) operations. The (multiple) DUs 122-1, 122-2 can be configured to handle the lower layers of the protocol stack, such as RLC, MAC, and L1. The user plane (U-plane) control function can interact with the MAC layer to encapsulate the RRC data received from the CU-CP 124 in a MAC packet and / or to de-encapsulate the RRC data from the MAC packet and provide the RRC data to the CU-CP 124. The (multiple) radio units of the (multiple) DUs 122-1, 122-2 can send / receive data to / from the (multiple) UEs via a radio interface.

[0099] As described above, one CU can include or be configured to control several DUs. In addition, one DU can serve multiple cells, such as dozens of cells. Providing the RRC layer in the CU 128 can achieve good control of the mobility of the UE 110 and also enable it to operate as a central resource manager for the UE 110. The DUs 122-1, 122-2 can include a resource manager that controls the use of lower layer radio parameters, such as periodic physical uplink control channel (PUCCH) resources, and some central processing unit (CPU) computing resources.

[0100] As an alternative or addition to the above functions, the communication network 100 may include other network function(s), network device(s), or protocol(s). Although some embodiments have been described in the context of 5G networks, it should be understood that the embodiments of the present disclosure are not limited to this example network. Thus, the example embodiments may be applied to any current or future communication network. A device may include or be configured to implement, for example via software, one or more of the protocol layers described herein. Figure 2 An example of components of a 5G New Radio (NR) network topology is illustrated. When a User Equipment (UE) moves in a wireless communication system, it may move within a radio coverage area (cell) supported by one or more radio access network nodes. When the UE moves within the radio coverage area, the ability to maintain effective communication of the UE with the wireless communication system is generally referred to as mobility. The operating characteristics of the cells supported by network access nodes within a wireless communication network may vary. A wireless communication system may include various Transmission and Reception Points (TRP).

[0101] It is envisioned that multiple Transmission and Reception Points mTRP may be used in a 5G NR network to improve reliability, coverage, and capacity performance through flexible deployment scenarios. The multi-TRP mitigates inter-cell interference via dynamic coordination between the multiple TRPs to provide joint scheduling and transmission / reception. A wireless device (such as a UE at the cell edge) may be served by multiple TRPs to improve signal transmission and / or reception, thereby increasing throughput. The following description may provide further details of alternatives, modifications, and variations in a 5G NR network: For example, a gNB may include a node that provides NR user plane and control plane protocol termination to the UE 110 and is connected to the 5GC via the NG interface, for example, according to Section 3.2 of 3GPP TS 38.300 V16.6.0 (3021-06) incorporated herein by reference.

[0102] The gNB Central Unit (gNB-CU) includes, for example, a logical node that hosts, for example, the RRC (Radio Resource Control), SDAP (Service Data Adaptation Protocol), and PDCP (Packet Data Convergence Protocol) protocols of the gNB, or the RRC and PDCP protocols of an en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface connected to the gNB-DU.

[0103] The gNB Distributed Unit (gNB-DU) includes, for example, a logical node that hosts, for example, the RLC (Radio Link Control), MAC (Media Access Control), and PHY (Physical) layers of the gNB or en-gNB, and whose operation is partially controlled by the gNB-CU. One gNB-DU supports one or more cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface connected to the gNB-CU.

[0104] The gNB-CU control plane (gNB-CU-CP) includes, for example, a logical node that hosts, for example, the control plane parts of the RRC and PDCP protocols for the gNB-CU of an en-gNB or 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.

[0105] The gNB-CU user plane (gNB-CU-UP) includes, for example, a logical node that hosts, for example, the user plane part of the PDCP protocol for the gNB-CU of an en-gNB, and the user plane parts of the PDCP protocol and the SDAP protocol for the gNB-CU of a 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 Section 3.1 of 3GPP TS 38.501 V16.6.0 (3021-07) incorporated by reference.

[0106] There can be different functional splits between the central and distributed units, for example, referred to as options:

[0107] Option A (Split type 1A): The functional split in this option is similar to the 1A architecture in DC. RRC is located in the central unit. PDCP, RLC, MAC, the physical layer, and RF are located in the distributed unit.

[0108] Option B (Split type 3C): The functional split in this option is similar to the 3C architecture in DC. RRC and PDCP are located in the central unit. RLC, MAC, the physical layer, and RF are located in the distributed unit.

[0109] Option C (Split within RLC): Low RLC (part of the functions of RLC), MAC, the physical layer, and RF are located in the distributed unit. PDCP and high RLC (the other part of the functions of RLC) are located in the central unit.

[0110] Option D (RLC-MAC split): MAC, the physical layer, and RF are located in the distributed unit. PDCP and RLC are located in the central unit.

[0111] Otherwise, for example, according to Section 11 of 3GPP TR 38.801 V14.0.0 (2017-03) incorporated by reference herein.

[0112] The gNB can support different protocol layers, such as Layer 1 (L1) - the Physical Layer. The Layer 2 (L2) of NR is split into the following sub-layers: Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Service Data Adaptation Protocol (SDAP), where for example: the Physical Layer provides a transport channel to the MAC sub-layer; the MAC sub-layer provides a logical channel to the RLC sub-layer; the RLC sub-layer provides an RLC channel to the PDCP sub-layer; the PDCP sub-layer provides a radio bearer to the SDAP sub-layer; the SDAP sub-layer provides a QoS flow to the 5GC; Comp. refers to header compression and Segm. refers to segmentation; the control channels include (BCCH, PCCH).

[0113] Layer 3 (L3) includes for example Radio Resource Control (RRC), for example, according to Section 6 of 3GPP TS38.300 V16.6.0 (3021 - 06) incorporated herein by reference.

[0114] RAN (Radio Access Network) nodes or network nodes or central nodes or distributed nodes (such as gNB, base station, gNB CU or gNB DU or parts thereof) can be implemented using, for example, a device having at least one processor and / or at least one memory (with computer-readable instructions (computer program)), the device being configured to support and / or provide and / or process CU and / or DU related functions and / or features, and / or at least one protocol (sub)-layer of the RAN (Radio Access Network), such as Layer 2 and / or Layer 3. They can also be implemented using specific components configured to perform corresponding specific tasks, such as Layer 3 components for performing Layer 3 operations, Layer 2 components for performing Layer 2 operations, etc. The central node can, for example, implement the CU-CP and / or CP-UP functions.

[0115] The gNB CU and gNB DU parts can, for example, be collocated or physically separated. The gNB DU can even be further split into two parts, for example, one part includes processing equipment and the other part includes antennas. The Central Unit (CU) can also be referred to as BBU / REC / RCC / C-RAN / V-RAN, O-RAN or a part thereof. The Distributed Unit (DU) can also be referred to as RRH / RRU / RE / RU or a part thereof.

[0116] The gNB-DU supports one or more cells and can thus be used as, for example, the serving cell for a User Equipment (UE).

[0117] In other words: the 5G base station or "network node" called gNB can be divided into two physical entities, namely the CU (Centralized Unit) and the DU (Distributed Unit).

[0118] The CU provides support for the upper layers of the protocol stack (such as SDAP, PDCP, and RRC (and especially layer 3 protocols such as 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 such as the physical layer and layer 2 protocols such as RLC and MAC)). Additionally, note that if the CU is connected to a 4G core network, the SDAP layer will not exist because we should have a 5G core network to support SDAP. There can be a single CU for each gNB, but one CU can control multiple DUs. For example, more than 100 DUs can be connected to one CU.

[0119] Each DU is capable of supporting one or more cells. Thus, different from 4G base stations, one gNB can control hundreds of cells. Additionally, note that the interface between the CU and the DU is called F1, and according to 3GPP, it should be an open interface. Therefore, you can connect a CU from supplier X to another DU from supplier Y.

[0120] A user equipment (UE) can include a wireless or mobile device, a device with a radio interface that interacts with the RAN (Radio Access Network), a smartphone, a vehicle-mounted device, an IoT device, an M2M device, etc. Such a UE or device can include: at least one processor; and at least one memory including computer program code; where the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to at least perform certain operations, such as an RRC connection with the RAN. The UE is configured, for example, to generate a message (e.g., including a cell ID) to be sent via radio towards the RAN (e.g., to and communicate with the serving cell). The UE can generate, send, and receive RRC messages containing one or more RRC PDUs (Packet Data Units).

[0121] The UE can have different states (e.g., according to Sections 4.1 and 4.4 of 3GPP TS 38.331 V16.5.0 (3021 - 06) incorporated herein by reference).

[0122] When the RRC connection has been established, the UE is, for example, in the RRC_CONNECTED state or the RRC_INACTIVE state.

[0123] In the RRC_CONNECTED state, the UE can: store the AS context; transfer unicast data to / from the UE; monitor the control channel associated with the shared data channel to determine whether data is scheduled for the data channel; provide channel quality and feedback information; and / or perform neighbor cell measurements and measurement reports;

[0124] The RRC protocol includes, for example, the following main functions: RRC connection control; measurement configuration and reporting; establishment / modification / release of measurement configuration (e.g., intra-frequency, inter-frequency, and inter-RAT measurements); establishment and release of measurement gaps; and / or measurement reporting.

[0125] With the development of the network, especially in the 5G New Radio (NR) system, inter-cell mobility is no longer controlled by the core network but is implemented such that it is configured to be centered on layer 1 (L1 or PHY layer) or layer 2 (L2 or MAC layer) (L1 / L2-centered). Within the 5G NR framework, various methods for implementing L1 / L2-centered inter-cell mobility are possible and can be selected according to different operating scenarios described further below.

[0126] Figure 3 An example of an apparatus configured to practice one or more example embodiments is illustrated. Apparatus 300 may include a device, such as, for example, a user equipment, an access node, an access point, a base station, a radio network node, or a split part thereof, or generally a device configured to implement the functions described herein. Apparatus 300 may include 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 attached DSP, or various other processing devices, which include 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, etc.

[0127] Apparatus 300 may also 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. For example, the memory may be embodied as a magnetic storage device (such as a hard disk drive, magnetic tape, etc.), a magneto-optical storage device, or a semiconductor memory (such as a mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.). The memory 304 is provided as an example of a (non-transitory) computer-readable medium. The term "non-transitory" used herein is a limitation on the medium itself (i.e., tangible, rather than a signal), rather than a limitation on the persistence of data storage (e.g., RAM versus ROM).

[0128] The apparatus 300 may further include a communication interface 308 configured to enable the apparatus 300 to send and / or receive information. The communication interface 308 may include an internal or external communication interface, such as, for example, an E1, F1, F1-C, and / or F2-C interface, or a radio interface. The apparatus 300 may also include other components and / or functions, such as, for example, a user interface (not shown) including 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 embedded control buttons. The output device may include, for example, a display, a speaker, etc.

[0129] When the apparatus 300 is configured to implement a certain function, a certain component and / or some components of the apparatus 300 (such as, for example, at least one processor 302 and / or at least one memory 304) may be configured to implement the function. In addition, when at least one processor 302 is configured to implement a certain function, the function may be implemented using, for example, program code 306 included in at least one memory 304.

[0130] The functions described herein may be performed at least in part by one or more computer program product components, such as software components. According to an example embodiment, the apparatus 300 includes a processor or processor circuitry, such as, for example, a microcontroller, which is configured (when executed) by program code 306 to perform embodiments of the operations and functions described herein. The program code 306 is provided as an example of instructions that cause the performance of the apparatus 300 when executed by at least one processor 302.

[0131] Alternatively or additionally, the functions described herein may be performed at least in part by one or more hardware logic components. For example, but not limited to, illustrative types of hardware logic components that may be used include field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on a chip (SOCs), complex programmable logic devices (CPLDs), graphics processing units (GPUs), etc.

[0132] Apparatus 300 may be configured to perform or cause the performance of the (multiple) methods described herein, or include components for performing the (multiple) methods described herein. In one example, the components include at least one processor 302 and at least one memory 304 including program code 306, which is configured to cause apparatus 300 to perform the (multiple) methods when executed by at least one processor 302. Generally, computer program instructions may be executed on components that provide general processing capabilities. Such components may be embedded, for example, in a personal computer, a smart phone, a network device, etc. Thus, the (multiple) methods may be implemented by a computer, such as (multiple) algorithms executable by general processing capabilities, an example of which is at least one processor 302. The components may include transmission or reception components, such as one or more radio transmitters or receivers (which may be coupled or configured to be coupled to one or more antennas), or (multiple) transmitters or (multiple) receivers of a wired communication interface. Although apparatus 300 is illustrated as a single device, it should be understood that, where applicable, the functions of apparatus 300 may be distributed among multiple devices.

[0133] Figure 4 An example of the latency associated with the layer 3 (L3) handover process is illustrated. The UE 110 may receive candidate configurations indicating one or more handover target cells. This may result in a processing latency T RRC (e.g., up to 10 ms) at the UE 110 for processing the radio resource control reconfiguration (RRCReconfiguration) message carrying the candidate configurations. The latency T proc,1 may refer to the UE processing time before the cell handover command. This may include L2 / L3 reconfiguration, retuning of the RF (radio frequency) section, baseband retuning, security updates, etc. This latency may be up to 20 ms for the same frequency range and up to 40 ms for different frequency ranges. When the target cell appears, a measurement latency T meas may occur between the appearance of the target cell and the cell handover command. After receiving the cell handover command, a latency T cmd may occur due to the processing of the L1 / L2 command (e.g., due to the hybrid automatic repeat request (HARQ) process and parsing). This latency may be up to 5 ms, for example. Another processing latency T proc,2 may occur after T cmd before the UE reconfiguration is complete. The duration of T proc,2 may be similar to T proc,1 and may occur for similar reasons.

[0134] The latency T 搜索may include the time required to search for the target cell. If the target cell is known, this delay may not exist, but if the target cell is unknown, this delay may be up to 60 ms. Due to the time taken for fine tracking and obtaining complete timing information, a delay T may occur Δ . This may depend on the Synchronization Signal / Block Measurement Timing Configuration (SMTC) and may be, for example, 20 ms. Due to the post-processing of Synchronization Signal Block (SSB) or Channel State Information Reference Signal (CSI-RS), a delay T may occur 余量 . Delay T 搜索 , T Δ and T 余量 may be associated with downlink (DL) synchronization.

[0135] Delay T IU may occur due to the interruption uncertainty when acquiring the first Physical Random Access Channel (PRACH) in the target cell. Delay T RAR may occur between the transmission of a Random Access (RA) preamble by UE 110 and the reception of a Random Access Response (RAR). Delay T IU and T RAR may be associated with uplink (DL) synchronization.

[0136] Delay T 第一数据 may occur between the reception of a Random Access Response by UE 110 and the initiation of data communication using the indicated beam. An interruption time may occur between the reception of a cell handover command and the initiation of data communication using the indicated beam. After that, data may be communicated with the new cell and the new Transmission Configuration Information (TCI) state.

[0137] Therefore, the RRC configuration received by UE 110 may include various configurations and processing it may take a long time. UE 110 may need to make a lot of effort to verify and process this configuration. Therefore, in a handover method, UE 110 may verify the RRC configuration when it is received and process the configuration when UE 110 exactly knows what to process. For example, in the case of an L3 handover, the time for UE 110 to perform this handover may be represented by T proc,2 .

[0138] In addition, the UE can process the RRC configuration in various ways. Some UEs may be able to process the complete RRC configuration when it is received, but other UEs may only verify the configuration and process it later. Therefore, some handover requirements may be designed based on the worst-case scenario. This may not be the best choice for LTM aiming to minimize the processing delay.

[0139] UE LTM RRC processing may include decoding and verification / compliance checking. UE 110 may determine to perform this operation after it receives a command or after a cell handover command is received. UE 110 typically does not provide the network with information on whether the command processing occurs before or after the handover command. Therefore, UE requirements can be designed again based on the worst-case scenario.

[0140] Example embodiments of the present disclosure provide methods for reducing the service interruption time associated with RRC processing in L1 / L2-triggered handovers. This can be achieved by addressing how to process RRC data at UE 110. UE 110 may indicate its RRC processing capabilities to the network, for example, via explicit signaling or via UE capabilities associated with the processing.

[0141] Compared with the UE latency associated with L3 handovers, at least the following areas for improvement can be determined:

[0142] The first set of methods (referred to herein as Options 1 to 3) includes example embodiments in which an LTM UL indication (LTM_UL_indication) is signaled from UE 110 to the network. This indication enables the network to be notified of the processing status of the RRC configuration at UE 110. Based on this information, the network can determine that UE 110 does not need to process the RRC configuration after receiving a cell handover command, and the UE service handover in LTM can have a shorter latency. Based on the LTM UL indication, the network can determine that UE 110 has performed a syntax symbol check and / or compliance check on the RRC configuration, such as an ASN.1 (Abstract Syntax Notation One) validity and / or compliance check.

[0143] The second method (Option 4) may include a downlink indication from the network to UE 110, for example, in an RRC reconfiguration command. This indication enables UE 110 to be requested to verify the received RRC-LTM configuration, process the RRC-LTM configuration, and / or prepare UE 110 for a cell handover before the cell handover command is received, for example, via a MAC CE or DCI.

[0144] The following terms may be used: LTM may refer to L1 / L2 triggered mobility. Cell handover may include, for example, the process of triggering a cell change via the LTM feature. Subsequent LTM may refer to the case of cell handover between L1 / L2 mobility candidates without RRC reconfiguration in between. The LTM configuration (LTM_config) may include one or more RRC configurations, which include LTM specific information elements. RRC ASN.1 verification may include verification of the general ASN.1 syntax and / or integrity verification. LTM evaluation (LTM_evaluation) may include the UE 110 evaluating the LTM configuration and extracting information, such as one or more of the following: user plane configuration (e.g., the (multiple) changes required for MAC, RLC, PDCP, or SDAP), whether RF retuning is required after the cell handover command (LTM_switch_command), whether baseband retuning is required after the cell handover command (LTM_switch_command), or whether the UE 110 is capable of performing a RACH-less access procedure (e.g., by evaluating the timing advance (TA) configuration). In response to the evaluation of the LTM configuration, the UE 110 may initiate preparation for further procedures, such as a RACH-less access procedure to the target DU. The LTM priority (LTM_priority) may include an indication of high priority for RRC-LTM configuration verification, processing, and / or preparation at the UE 110. The LTM uplink (UL) indication (LTM_UL_indication) may indicate whether the UE110 is capable of processing the LTM configuration before the cell handover command. The LTM UL indication may indicate which parts of the RRC configuration still need to be processed after the cell handover command. The LTM switch command (LTM_switch_command) may include a cell handover 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.

[0145] One or more of the following performance enhancements may be the goal:

[0146] - L1 / L2-based mobility may not need to support security updates.

[0147] - After receiving the candidate cell configuration, ASN.1 decoding and validity / compliance checking of the candidate cell configuration may be performed.

[0148] - For UE processing, the following (non-exhaustive) operations may be performed after receiving the cell handover command: MAC / RLC reset (when configured), RF retuning (e.g., required for inter-frequency), baseband retuning.

[0149] - Before receiving a cell handover command, perform DL synchronization on the candidate / target cell, for example, at least when the target cell is already an active serving cell.

[0150] - Support tracking reference signal (TRS) tracking and CSI measurement of the candidate / target cell before / by the cell handover command.

[0151] L1 / L2-based mobility can be configured to support the following carrier aggregation (CA) scenarios: the PCell (primary cell) changes without SCell change, or the PCell changes and the SCell changes. In addition, support for the NR-DC scenario in L1 / L2-based mobility can be provided, at least for the case of PSCell (primary cell and secondary cell) change without the participation of the master node (MN), i.e., within the SN (secondary node).

[0152] The following scenarios can be considered for L1 measurement and beam indication:

[0153] - Event reporting or filtering can be supported.

[0154] - Inter-frequency L1 / L2 mobility: Inter-frequency scenarios of L1 / L2 mobility (including moving to an inter-frequency cell that is not the current serving cell) can generally be supported, including support for inter-frequency L1 measurement.

[0155] - The unified TCI framework can be used for beam indication of L1 / L2 mobility.

[0156] The following scenarios can be considered for dynamic cell handover:

[0157] - L1 / L2 mobility trigger information can be transmitted in the MAC CE. The MAC CE or DCI can be used for the actual trigger of L1 / L2 mobility.

[0158] - The MAC CE for L1 / L2 mobility trigger can contain at least the candidate configuration index.

[0159] - Perform SCell activation / deactivation simultaneously with the L1 / L2 mobility trigger MAC CE (e.g., between the SCells associated with the candidate configuration).

[0160] - Support RACH-based (e.g., contention-free random access (CFRA), contention-based (CBRA)) and RACH-less procedures for L1 / L2 mobility handover.

[0161] For example, if the UE does not need to obtain timing advance (TA) during cell handover,

[0162] then RACH-less access can be used.

[0163] - The RACH resources for CFRA for L1 / L2 dynamic switching can be provided in RRC configuration or MAC CE.

[0164] - The MAC CE can indicate the (multiple) TCI states (or other beam information) to be activated for the (multiple) target cells.

[0165] - At L1 / L2 cell handover: Whether the UE performs partial or full MAC reset, re - establish RLC, and perform data recovery using PDCP can be controlled by the network. This can be configured by RRC. Alternatively or additionally, (multiple) MAC CE indications can be used.

[0166] Figure 5A and Figure 5B illustrates an example of a message sequence and operations for L1 / L2 triggered mobility. L1 / L2 related processes can involve UE 110, DU 122 - 1 (acting as the source DU in this example), DU 122 - 2 (target DU), and CU 128. As Figure 1 shown, the source DU 122 - 1 and the target DU 122 - 2 can be associated with the same CU 128, e.g., controlled by it. However, the disclosed L1 / L2 mobility processes can be performed on DUs associated with different CUs. The operations of the source DU 122 - 1, target DU 122 - 2, and CU 128 can be performed by an access node (e.g., gNB 120).

[0167] At operation 501, the UE 110 can send an L3 measurement report to the source DU 122 - 1.

[0168] At operation 502, the source DU 122 - 1 can send the L3 measurement report to the CU 128, e.g., using UL RRC message transfer.

[0169] At operation 503, the CU 128 can make a handover decision. This decision can be based on the L3 measurement report.

[0170] At operation 504, the CU 128 can send a UE context establishment request to the target DU 122 - 2. The UE context establishment request can be a CU - initiated context establishment request.

[0171] At operation 505, the target DU 122 - 2 can send a UE context establishment response to the CU 128.

[0172] At operation 506, the CU 128 can send a UE context modification request to the source DU 122 - 1.

[0173] At operation 507, the source DU 122-1 may send a UE context modification response to the CU 128.

[0174] At operation 508, the CU 128 may generate an RRC (re)configuration for LTM (RRC-LTM). The RRC-LTM (re)configuration may include a measurement configuration for L1 cell change and / or a configuration of a target cell prepared for handover.

[0175] At operation 509, the CU 128 may send an RRC message to the source DU 122-1, for example, using downlink (DL) RRC messaging. The RRC message may include the RRC-LTM (re)configuration generated at operation 508.

[0176] According to one method, after operation 509, an RRC reconfiguration message may be sent from the source DU 122-1 to the UE 110, an RRC reconfiguration complete message may be sent from the UE 110 to the source DU 122-1, and a periodic transmission of L1 measurement reports may be made from the UE 110 to the source DU 122-1, which may trigger a handover. However, operations 510 to 519 as described herein enable a reduction in latency when performing a handover. The transmission of the L1 measurement reports may initiate a handover execution phase, which may be after a handover preparation phase, which may include, for example, operations up to the transmission of the L1 measurement reports.

[0177] At operation 510, the source DU 122-1 may send 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 a priority (LTM_priority) for the verification, processing, or preparation of the RRC configuration at the UE 110. The indication of the priority may be set to a (high) value that indicates a request to prioritize the verification, processing, or preparation of the RRC configuration at the UE 110, for example, such that the RRC configuration is verified, processed, or prepared before the receipt of a cell handover command at the UE 110 (see operation 518). Alternatively, the LTM_config or LTM_priority may be sent in some other control message. Operation 510 is provided as an example implementation of option 4 above.

[0178] At operation 511, the UE 110 may perform verification of the received LTM_config. For example, the UE 110 may perform verification of the syntax notation check of the RRC configuration (LTM_config), such as ASN.1 verification. This may include verification of the ASN.1 syntax of the LTM_config, but for example, not necessarily verification of the integrity of the LTM_config.

[0179] At operation 512, the UE 110 may perform LTM evaluation and LTM configuration preparation. For example, the UE 110 may evaluate the feasibility of processing the LTM_config (e.g., RRC incremental configuration). The UE 110 may extract the LTM configuration but has not applied any part of it yet. The UE 110 may evaluate the user plane configuration, such as whether the (multiple) MAC, RLC, PDCP, or SDAP protocol configurations need (multiple) changes, whether RF or baseband retuning is required to comply with an upcoming cell handover command, or whether the UE 110 can access the target DU 122-2 via a RACH-less access procedure. Based on this evaluation, the UE 110 may determine how much the latency of the process is.

[0180] The UE 110 may determine the latency based on static latency calculations. For example, the following latency requirements may be specified: RACH latency is 10 ms, RACH-less latency is 0, RF retuning latency is 5 ms (inter-frequency only), baseband retuning is 5 ms, in-DU MAC is 5 ms, inter-DU MAC is 10 ms, in-DU RLC latency is 5 ms, inter-DU RLC latency is 5 mis, MAC CE processing is 5 ms. When the UE 110 receives an RRC configuration including these case-specific pointers, the UE 110 may calculate that, for example, the preparation latency in a RACH-less in-DU with in-frequency LTM is a total of RACH-less 0 ms + MAC 5 ms + RLC 5 ms + MAC CE (cell handover) 5 ms = 15 ms. It should be noted that these numbers are for illustrative purposes only.

[0181] Generally, the UE 110 may determine whether it can process the RRC configuration (LTM_config) before receiving the cell handover command. The UE 110 may estimate the latency for processing the RRC configuration (LTM_config). Operations 511 and / or 512 may be initiated by the UE 110 in response to receiving an indication of LTM_priority at operation 510.

[0182] At operation 513, the UE 110 may send an LTM UL indication to the source DU 122-1. The LTM UL indication may include an indication of whether the UE 110 can process the RRC configuration (LTM_config) before receiving the cell handover command and / or an indication of the estimated latency. The indication may include an indication that the UE 110 has processed the received RRC configuration (LTM_config), i.e., an indication of processing completion. According to option 1, the LTM UL indication may be sent in the RRC reconfiguration complete message.

[0183] At operation 514, UL RRC message transfer may be performed between the source DU 122-1 and the (target) CU 128.

[0184] At operation 515, according to option 2, the UE 110 may send an LTM UL indication to the source DU 122-1 in the 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.

[0185] At operation 516, according to option 3, the UE 110 may send an LTM UL indication to the source DU 122-1 in the L1 measurement report. Any one of options 1 to 3 may be combined with option 4 (see operation 510). It should also be noted that if an LTM UL indication is provided in another one of these messages, one or more of the messages of options 1 to 3 (without the LTM UL indication) may be sent.

[0186] Alternatively, the LTM UL indication may be implicit. For example, the UE 110 may be configured to have the ability to perform RRC preprocessing. After the network (e.g., gNB 120) sets the corresponding configuration flag in the RRC configuration, the network may determine that the UE110 is configured to perform LTM evaluation before sending the L1 measurement. Therefore, for example, when the same information is determined by the network based on UE capability signaling, an explicit LTM UL indication may not be required.

[0187] For example, in some examples, the ability of LTM RRC delay processing may not be explicitly indicated via the UL indication, but may be specified by UE behavior and requirements, such as in the standard. In this case, the network (e.g., gNB 120) may determine that the processing of the RRC configuration occurs at the UE 110 Figure 4 A or Figure 4 after / before a specific operation of B, for example, after any operation before operation 518.

[0188] The UE 110 may alternatively provide the information of the LTM UL indication as UE capability. When the UE 110 supports this capability, the network (e.g., gNB 120) may determine that the UE 110 is configured to process the RRC configuration in the specified steps. The UE capability may indicate, for example, at least one of the following:

[0189] - The UE 110 is configured to perform ASN.1 verification and LTM evaluation (see operations 511 and 512) in response to receiving the RRC configuration at operation 510, for example, immediately after operation 510 (e.g., as the next operation after receiving the RRC configuration)

[0190] (together or separately).

[0191] - The UE 110 is configured to perform (only) operation 511 in response to receiving the RRC configuration at operation 510.

[0192] - The UE 110 is configured to process the RRC configuration (LTM_config) between operations 516 and 518.

[0193] - The UE 110 is configured to process the RRC configuration (LTM_config) before or after starting L1 measurements.

[0194] - 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 configuration of the target DU can trigger LTM evaluation at the UE 110.

[0195] - The UE 110 may perform LTM processing (e.g., ASN.1 verification / evaluation) at any time before the LTM_switch_command.

[0196] In some examples, LTM evaluation and syntax symbol (e.g., ASN.1) verification can be performed simultaneously, e.g., in parallel. The UE 110 may decide to perform ASN.1 verification (see operation 511) separately from the LTM evaluation (see operation 512).

[0197] In some examples, the UE 110 may apply the RRC configuration directly after receiving it. The UE 110 may be configured to do so, e.g., when the UE 110 is configured with multi-rx / tx capabilities, or when the UE 110 has multiple protocol stacks in which the RRC configuration can be applied. In this case, in response to receiving a cell handover command, the UE 110 may switch to a pre-configured RX / TX chain or protocol stack.

[0198] In some examples, the UE capabilities may indicate that the UE 110 cannot perform RRC preprocessing. In this case, compared to a UE capable of RRC preprocessing, the UE 110 may use L3 handover requirements, or alternatively relax the measurements (e.g., a longer time interval between measurements or measurement reports). Alternatively, the ability to perform RRC preprocessing may be indicated via LTM_UL_indication (e.g., using one of options 1 to 3). The RRC preprocessing ability may refer to the ability to process the RRC configuration (LTM_config) before the cell handover command.

[0199] Source DU 122-1 can thus receive an LTM UL indication, e.g., in an RRC reconfiguration complete message, in a MAC CE, in an L1 measurement report, or as part of the UE capabilities of UE 110. After receiving the LTM UL indication, the network (e.g., source DU 122-1) can assume a different latency profile for UE 110 than when there is no indication.

[0200] At operation 517, source DU 122-1 can decide to perform a serving cell change for UE 110. This can be based on one or more conditions, such as conditions of L1 handover measurements reported by UE 110. Based on the LTM UL indication (e.g., the ability of UE 110 to process RRC reconfiguration before a cell handover command, the estimated latency in such processing, or an indication of completion of such processing), source DU 122-1 can configure at least one latency value of the handover procedure, e.g., one or more of latency values D or T, as described below.

[0201] In L1 / L2-triggered mobility, the LTM latency can include an LTM preparation latency and an LTM execution latency, e.g., as follows:

[0202] D LTM = D LTM_preparation + D LTM_execution .

[0203] When UE 110 receives an RRC message indicating an LTM handover, UE 110 can perform the LTM preparation procedure for LTM. The LTM RRC preparation latency can include an LTM ASN.1 verification latency and an LTM RRC evaluation latency:

[0204] T RRC_preparation_delay = T ASN.1_validation + T RRC_LTM_evaluaion , where

[0205] - T RRC_preparation_delay is the latency of RRC preprocessing (which can include ASN.1 verification latency and LTMRRC configuration evaluation latency),

[0206] - T ASN.1_validation is the ASN.1 configuration verification latency, and

[0207] - T RRC_LTM_evaluation is the latency required for UE 110 to perform LTM configuration evaluation and extract the user plane (MAC / RLC / PDCP / SDAP) and / or L1 processing indication of the RRCLTM command.

[0208] The LTM execution time T LTM_executionThe UE execution preparation time that may include LTM. The LTM execution time may start after the UE 110 receives a cell handover command (LTM handover command). For example,

[0209] T LTM_execution = T RRC_LTM_execution_intra + T LTM_switch_command , where

[0210] -T RRC_execution is the UE delay (RRC configuration) for applying the LTM RRC configuration to L1 and L2 as indicated by the RRC command, and

[0211] -T LTM_switch_command is the delay for extracting the target cell information from the handover command and applying the

[0212] LTM RRC configuration.

[0213] The LTM processing requirements may be separated within frequency and between frequencies, for example, the LTM execution time provided in the following table:

[0214]

[0215]

[0216] Therefore, due to the fast characteristics of LTM, the RRC delay can be split into multiple components instead of a single delay. In addition, the preparation and verification operations (see Operations 511 and 512) can be separated, for example, as described below:

[0217] LTM RRC Processing: If the UE supports the L1 / L2-triggered mobility capability (e.g., L1L2-triggered-mobility-r18), the UE RRC processing may include the execution of the LTM-related components included in the RRC preparation and RRC configuration messages (see LTM_config, Operation 510).

[0218] D LTM = D LTM_preparation + D LTM_execution , where:

[0219] -D LTM is the total processing delay including LTM RRC message processing, RRC evaluation, and application of RRC configuration to L1 and L2 at the UE 110.

[0220] -T LTM_Preparation is the delay component associated with LTM preparation at the UE 110. This delay may include LTMRRC message processing, RRC, and evaluation of L1 and L2 configurations.

[0221] -TLTM _ Execution is the delay component, which is used to configure LTM for L1 and L2 based on the LTM handover command. This can be determined based on RRC evaluation.

[0222] LTM RRC Processing with UL Processing 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 may indicate that UE 110 has performed LTM preparation (T LTM_preparation ), and (only) the remaining delay T LTM_execution is left. In this case, the network (e.g., gNB 120, e.g., source DU 122-1) may configure the delay value D LTM as follows:

[0223] D LTM = T LTM_Execution .

[0224] Alternatively, the same effect can be achieved by configuring T LTM_preparation = 0. If the UL indication includes the LTM execution time (T LTM_execution ), the network (e.g., source DU 122-1) may use this delay for LTM execution. For example, when UE 110 has processed the RRC configuration upon receipt and has made no further preparations (e.g., in the case within the DU), the network may determine the execution time corresponding to T cmd in the L3 handover. Additionally, if UE 110 processes the RRC incremental configuration and there is nothing to change, the same delay may be applied. If no UL indication is received from UE 110 (or the UL indication indicates that UE 110 cannot process the RRC reconfiguration before the cell handover command), the following delay may be applied after the cell handover command (LTM handover instruction).

[0225] D LTM = T LTM_Preparation + T LTM_Execution

[0226] LTM Processing Sequence: If UE 110 supports L1 / L2-triggered mobility (e.g., L1L2-triggered-mobility-r18), UE 110 may perform LTM preparation (T Preparation ) before the cell handover command (LTM handover command), and perform LTM execution (T LTM _ Execution ) after the cell handover command.

[0227] At operation 518, source DU 122-1 may send a cell handover command (LTM handover command), e.g., as a MAC CE configured to trigger a cell change.

[0228] At operation 519, UE 110 may apply the RRC reconfiguration (LTM_config). The application of the RRC configuration may be in response to receiving the cell handover command from source DU 122-1. UE 110 may, for example, perform the actions left after the LTM evaluation of operation 512. UE 110 may, for example, configure its hardware based on the processing of the RRC (re)configuration in operation 512. UE 110 may apply the latency estimated in operation 512 and indicated to source DU 122-1, for example, in one of operations 513, 515, or 516. UE 110 may, for example, apply the RRC configuration (LTM_config) within the estimated latency. Operation 519 may fully or partially include operation 511 or 512.

[0229] At operation 520, a random access may be initiated between UE 110 and target DU 122-2. For example, UE 110 may send a random access preamble to target DU 122-2.

[0230] At operation 521, in response to receiving the random access preamble at operation 520, target DU 122-2 may send a random access (RA) response to UE 110.

[0231] At operation 522, UE 110 may send an RRC reconfiguration complete message to target DU 122-2. The transmission of the RRC reconfiguration complete message may terminate the handover execution phase.

[0232] At operation 523, UE UL RRC message transmission may be performed between target DU 122-2 and CU 128, e.g., to notify CU 128 of the completion of the RRC reconfiguration at UE 110. The UL RRC message transmission may initiate the handover completion phase.

[0233] At operation 524, CU 128 may send a UE context release command to source DU 122-1. In response to receiving this message, source DU 122-1 may release the UE context of UE 110.

[0234] At operation 525, source DU 122-1 may send a UE context release complete message to CU 128, e.g., to notify CU 128 of the release of the UE context of UE 110 at source DU 122-1.

[0235] At operation 526, a path switch from source DU 122-1 to target DU 122-2 can be performed. For example, a data packet to be delivered to UE 110 can be switched to be delivered to target DU 122-2 instead of source DU 122-1.

[0236] Four example options (Options 1 to 4) are provided for notifying the network of the handling capabilities / status of an RRC-LTM reconfiguration. In addition, the UE 110 and the network are notified of the LTM capabilities. The following description provides more examples of the following:

[0237] - UE capability signaling for LTM handling.

[0238] - Option 1: The UE sends a UL indication in the RRC reconfiguration complete message;

[0239] - Option 2: The UE sends an LTM_UL_indication via a MAC CE (new MAC CE);

[0240] - Option 3: The UE sends an LTM_UL_indication within an L1 measurement report.

[0241] Figure 6 An example of UE capability exchange for LTM is illustrated. The RRC handling capabilities of UE 110 can be indicated to the network, for example, so that the network can follow the procedures described herein. This can be achieved by utilizing UE capability signaling. This capability signaling can be independent of the LTM feature or can be associated with the LTM feature. For example, if UE 110 supports the LTM capability (e.g., a flag can be named L1L2TriggeredMobility-rel-18), the behavior of this capability can be specified in the standard (e.g., in TS 38.133). If UE 110 supports the LTM capability, this indication can be an optional parameter, which can be sent in the RRC establishment response message or configured by the network in the RRC establishment message.

[0242] UE 110 can report its UE radio access capabilities, which can be static, for example, at least when requested by the network. The gNB can request UE 110 to report specific capabilities based on band information. UE capabilities can be represented by a capability ID, which can be exchanged in non-access stratum (NAS) signaling on the radio interface and in network signaling, rather than in the UE capability structure.

[0243] This capability can be signaled using, for example, a flag (e.g., L1L2-TriggeredMobility-r18) or a similar flag, or inherently by indicating support for a standard or its version / release (e.g., Rel.18). This capability can be signaled via UECapabilityInformation and / or UECapabilityInformation-InformationElements (IE) (RRC).

[0244] At operation 601, the CU 128 can send a UE capability query, which can be transparently sent by the source DU 122-1 to the UE 110.

[0245] At operation 602, the UE 110 can respond to the query (e.g., together with other capabilities) by indicating its support for LTM (e.g., via the capability L1L2TriggeredMobility-r18) and / or LTM RRC preprocessing (e.g., via the capability L1L2-TriggeredMobility-RRCPreprocessing-r18).

[0246] At operation 603, the CU 128 can send UE LTM capability information to the source DU 122-1. The source DU 122-1 can consider this capability information in its cell handover post-processing and scheduling decisions.

[0247] At 604, the CU 128, the source DU 122-1, and the UE 110 are aware of LTM processing.

[0248] The following table provides an example definition of UE capability signaling, where M can indicate a mandatory feature, BC can indicate a band combination, FDD / TDD can indicate whether the feature is FDD / TDD differentiated, and FR1 / FR2 can indicate whether the feature is FR1 / AR2 differentiated. N / A can indicate no expected impact. Note that if, for example, L1L2-TriggeredMobility-r18 is only supported for FR2, this feature can still be used for FR2. This may not be a technical limitation but a limitation of the UE implementation.

[0249]

[0250] Based on UE capability signaling, the CU 128 can be notified that the UE 110 supports LTM preprocessing. However, the source DU 122-1 and the target DU 122-2 may not be aware of this. It may be necessary to notify the source DU 122-1 whether the UE 110 supports RRC preprocessing to make a cell change decision. Therefore, the CU 128 can 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 can apply this configuration assumption after MAC CE processing. This configuration can define the UE RRC processing delay profile for the application of RRC reconfiguration (LTM_config_application).

[0251] Figure 7 illustrates an example of the delivery of LTM capability information. Initially, UE capability exchange can be performed, for example, as referenced Figure 6 as described. This can include the transmission of L3 reports between the UE 110 and the DU.

[0252] The CU 128 can send the UE LTM capability information to the source DU 122 1.

[0253] The UE 110 can send an L3 measurement report to the source DU 122-1.

[0254] The source DU 122-1 can forward the L3 measurement report to the CU 128, for example, via UL RRC message transfer.

[0255] The CU 128 can make a handover decision.

[0256] The CU 128 can create a UE delay profile for the UE 110 based on the UE capability information. The CU 128 can consider all UE LTM processing when creating the delay profile.

[0257] The CU 128 can send the UE configuration to one or more (e.g., all) candidate target cells ((multiple) target DUs). Alternatively, the CU 128 can send this information to the source DU 122-1. The source DU 122-2 can send this information to the (multiple) target DUs before the LTM handover decision.

[0258] The remaining operations can be similar to those referenced Figure 5A or Figure 5B described. However, the source DU 122-1 can apply the LTM UE delay profile before deciding to change the serving cell or sending a cell handover command.

[0259] Figure 8A and Figure 8BIllustrates an example of a message sequence and operations when sending an LTM uplink indication in an RRC reconfiguration complete message. The operations of these figures can be similar to Figure 5A or Figure 5B the corresponding operations, and have the following notes.

[0260] After DL message transfer (see operation 509), the network can know the LTM capability of UE110, for example, via UE capability information exchange. LTM evaluation (see operation 512) can be performed before the transmission of LTM_UL_indication in the RRC reconfiguration complete message. This can be referred to as option 2.1. In ASN.1 verification, only the ASN.1 syntax can be verified. The LTM UL indication included in the RRC reconfiguration complete message can be configured to indicate to the network that UE 110 has processed the RRC configuration. For example, this can be achieved by including an optional parameter in the RRC message, such as under L1L2TriggeredMobility-r18:rrcPreprocessing = true / yes / 1. When set to a logical false value, this parameter can indicate that UE 110 is unable to perform preprocessing. The message can also contain a set of parameters that indicate what changes (RRC reconfiguration) UE 110 has made and / or what changes are still required after LTM_switch_command, for example, during the operation of applying the LTM configuration. At LTM_config_application, UE 110 can perform the actions left in LTM_evaluation. UE110 can configure its hardware based on the RRC reconfiguration. UE 110 can apply the delay indicated in the RRC reconfiguration complete message. LTM_config application can also fully or partially include the steps of ASN.1 verification and LTM_evaluation.

[0261] Figure 9A and Figure 9B Illustrates an example of a message sequence and operations when sending an LTM uplink indication in a MAC CE (option 2). The operations of these figures can be similar to Figure 5A 、 Figure 5B 、 Figure 8A or Figure 8BThe corresponding operations, and have the following notes. The UE 110 can perform LTM evaluation before (Option 2.1) or after (Option 2.2) the transmission of the RRC reconfiguration complete message. The UE 110 can send LTM_UL_Indication in the MAC CE (see Operation 515). The UE 110 can indicate via a dedicated MAC CE that it has processed the RRC configuration. The UE 110 can also provide information on how long the processing is expected to take after the cell handover command. This information can be provided, for example, as an index to a mapping table describing the processing values, such as follows:

[0262]

[0263] The source DU 122-1 can apply a new delay profile for the UE based on the MAC CE.

[0264] At LTM_config_application, the UE 110 can perform the actions left over from LTM_evaluation. The UE 110 can configure its hardware based on the RRC reconfiguration. The UE 110 can apply the delay indicated in the MAC CE. Alternatively, the delay can be static, for example specified in the standard. The LTM_config application can also fully or partially include ASN.1 verification and steps from LTM_evaluation.

[0265] Figure 10A and Figure 10B Illustrates an example of the message sequence and operations when sending an LTM uplink indication in the MAC CE (Option 3). The operations in these figures can be similar to Figure 5A 、 Figure 5B 、 Figure 8A or Figure 8B The corresponding operations, and have the following notes. The UE 110 can perform LTM evaluation before (Option 2.1) or after (Option 2.2) the transmission of the RRC reconfiguration complete message. The UE 110 can send LTM_UL_Indication in the L1 measurement report (see Operation 516). The UE 110 can indicate via the L1 measurement report that it has processed the RRC configuration. The UE 110 can also provide information on how long the processing is expected to take after the cell handover command. This information can be provided, for example, as an index to a mapping table describing the processing values, as described above with reference to the option.

[0266] Alternatively, the indication via the L1 measurement report can be implicit. For example, UE 110 may send a first L1 measurement report. UE 110 may be configured to send the L1 report only after it has completed the LTM_evaluation process. Based on the reception of the (first) L1 measurement report, the source DU 122-1 may determine that UE 110 has completed the LTM evaluation. For example, UE 110 may have the ability to perform RRC preprocessing. After the network sets a configuration flag in the RRC configuration, the network may assume that UE110 has performed LTM_evaluation before sending the L1 measurement.

[0267] In response to receiving the LTM_UL indication in the L1 measurement report, the source DU 122-1 may consider a new latency profile. For example, the source DU 122-1 may apply a new latency profile for the UE based on the L1 measurement report.

[0268] At LTM_config_application, UE 110 may perform the actions left over from LTM_evaluation. UE 110 may configure its hardware based on the RRC reconfiguration. UE 110 may apply the latency indicated in the L1 measurement report. Alternatively, the latency may be static, e.g., specified in a standard. The LTM_config application may also fully or partially include steps from the ASN.1 verification and LTM_evaluation.

[0269] Figure 11A and Figure 11B illustrates an example of a message sequence and operations when the RRC configuration indicates the LTM priority (option 4). The operations in these figures may be similar to Figure 5A , Figure 5B , Figure 8A or Figure 8B 's corresponding operations and have the following notes.

[0270] The RRC reconfiguration sent by the source DU 122-1 to UE 110 may indicate that the UE is requested or commanded to process the received LTM RRC configuration step by step. This may be either before or after the completion of the RRC reconfiguration, depending on the complexity of the configuration.

[0271] Examples of requirements for LTM are as follows. These requirements may apply to LTM, such as changing the NR PCell to another NR cell, or changing from an NR SCell to another SCell.

[0272] NR FRx - NR FRx LTM: These example requirements may apply to both intra-frequency and inter-frequency LTM from an NR FRx cell to an NR FRx cell.

[0273] LTM Delay: The process delay for all processes where an LTM handover can be commanded can be specified in the standard. The LTM delay can include or consist of an LTM preparation delay and an LTM execution delay:

[0274] D LTM = D LTM_preparation + D LTM_execution .

[0275] When UE 110 receives an RRC message indicating an LTM handover, UE 110 can perform the LTM preparation process for the LTM. The LTM RRC preparation delay can include an LTM ASN.1 verification delay and an LTM RRC evaluation delay.

[0276] T RRC_peparation_delay = T ASN.1_validation + T RRC_LTM_evaluation

[0277] Where:

[0278] - T RRC_preparation_delay is the delay for RRC preprocessing. This processing includes an ASN.1 verification delay and an LTM RRC configuration evaluation delay

[0279] - T ASN.1_validation ASN.1 configuration verification delay

[0280] - T RRC_LTM_evaluation is the delay required for the UE to perform the LTM configuration evaluation and extract the user plane (MAC / RLC / PDCP / SDAP) and L1 processing instructions of the RRC LTM command.

[0281] LTM execution time T LTM_execution is the UE execution preparation time for the LTM, and it can start after the UE receives the LTM handover command:

[0282] T LTM_execution = T RRC_LTM_execution_intra + T LTM_switch_command

[0283] Where:

[0284] - T RRC_execution is the UE delay for applying the LTM RRC configuration to L1 and L2 as indicated by the RRC command.

[0285] - T LTM_switch_command is the delay for extracting the target cell information from the handover command and applying the target cell information.

[0286] The LTM processing requirements are separable for intra-frequency and inter-frequency.

[0287]

[0288] Figure 12 An example of a method for indicating the ability to preprocess RRC reconfiguration before cell handover is illustrated.

[0289] At 1201, the method may include the user equipment receiving a radio resource control (RRC) reconfiguration message associated with a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) process.

[0290] At 1202, the method may include determining whether the user equipment is capable of preprocessing at least a portion of the radio resource control reconfiguration message associated with layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) before receiving a cell handover command for performing a cell handover.

[0291] At 1203, the method may include performing preprocessing of at least a portion of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related portion of the received RRC reconfiguration message.

[0292] At 1204, the method may include sending a message to a network node of the radio access network to which the user equipment is connected, the message including: an indication related to a preprocessing portion of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related portion of the radio resource control reconfiguration message before receiving a cell handover command.

[0293] Figure 13 An example of a method for preprocessing RRC reconfiguration is illustrated.

[0294] At 1301, the method may include the user equipment receiving a radio resource control (RRC) reconfiguration message associated with a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) process, the RRC reconfiguration message including: an instruction to preprocess at least a portion of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related portion of the received RRC message.

[0295] At 1302, the method may include: determining whether the user equipment is capable of preprocessing the indicated at least a portion of the radio resource control reconfiguration message associated with layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) before receiving a cell handover command for performing a cell handover.

[0296] At 1303, the method may include 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.

[0297] Figure 14 An example of a method for indicating the ability of a UE to preprocess RRC reconfiguration before cell handover is illustrated.

[0298] At 1401, the method may include establishing, by a user equipment (UE), a connection to a network node of a radio access network.

[0299] At 1402, the method may include the UE sending, to the network node, a UE capability indication that is related to the ability to support layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) operations and that is related to the support of preprocessing of at least a part of a radio resource control reconfiguration message related to layer 1 / layer 2 (L1 / L2) triggered mobility (LTE) before receipt of a cell handover command for performing a cell handover.

[0300] At 1403, the method may include the user equipment receiving a radio resource control (RRC) reconfiguration message associated with a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) procedure.

[0301] At 1404, the method may include performing preprocessing of at least a part of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM)-related part of the received RRC message.

[0302] Figure 15 An example of a method for configuring one or more LTM delays based on an indication related to a preprocessing part of an RRC reconfiguration message related to LTM is illustrated.

[0303] At 1501, the method may include: a network node of a radio access network sending, to a user equipment, a radio resource control (RRC) reconfiguration message associated with a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) procedure.

[0304] At 1502, the method may include: receiving, from a user equipment connected to the radio access network, a message that includes: an indication related to a preprocessing part of a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM)-related part of a radio resource control reconfiguration message before receipt of a cell handover command.

[0305] At 1503, the method may include configuring, for the user equipment, at least one delay value for a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) procedure based on an indication related to a preprocessing part of a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM)-related part of a radio resource control reconfiguration message made by the user equipment.

[0306] Figure 16A method for instructing at least a part of an LTM-related part of a UE to preprocess an RRC message is illustrated.

[0307] At 1601, the method may include a network node sending a radio resource control (RRC) reconfiguration message associated with a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) procedure to a user equipment, the RRC reconfiguration message including: an instruction for preprocessing at least a part of an LTM-related part of a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) of an RRC message.

[0308] Figure 17 A method for configuring one or more LTM delays based on an indication of a UE's ability to support LTM preprocessing is illustrated.

[0309] At 1701, the method may include a network node of a radio access network establishing a connection with a user equipment (UE).

[0310] At 1702, the method may include receiving, from the UE, a UE capability indication related to the ability to support a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) procedure and related to the support for preprocessing at least a part of a radio resource control reconfiguration message related to a layer 1 / layer 2 (L1 / L2) triggered mobility (LTE) before receiving a cell handover command for performing a cell handover.

[0311] At 1703, the method may include configuring, for the user equipment, at least one delay value for a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) procedure based on an indication related to a preprocessing part of an LTM-related part of a radio resource control reconfiguration message performed by the user equipment.

[0312] As described in the specification, claims, and drawings, other features of these methods directly result from the functions of one or more DUs 122-1, 122-2, CUs 128, or UEs 110, and thus are not repeated here. An apparatus may be configured to perform any aspect of the one or more methods described herein or cause these aspects to be performed. Additionally, a computer program or computer program product may include instructions for causing an apparatus to perform any aspect of the one or more methods described herein when executed by the apparatus. Additionally, an apparatus may include components for performing any aspect of the one or more methods described herein. According to an example embodiment, the components include at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform at least any aspect of the one or more methods described herein.

[0313] Other method examples are provided below:

[0314] A method may include: receiving, by a user equipment, a radio resource control configuration associated with a handover procedure; determining whether the user equipment is capable of processing the radio resource control configuration before receiving a cell handover command of the handover procedure; and sending an indication to a source distributed node of the handover procedure as to whether the user equipment is capable of processing the radio resource control configuration before receiving the cell handover command.

[0315] According to an example embodiment, the handover procedure includes a layer 1 or layer 2 inter-cell mobility procedure, and wherein the radio resource control configuration includes a layer 1 or layer 2 mobility configuration.

[0316] According to an example embodiment, the method may include: receiving a cell handover command from the source distributed node; and applying the radio resource control configuration in response to receiving the cell handover command.

[0317] According to an example embodiment, the method may include: estimating a latency for processing the radio resource control configuration; and sending an indication of the estimated latency for processing the radio resource control configuration to the source distributed node.

[0318] According to an example embodiment, the method may include: receiving a cell change command from the source distributed node; and applying the radio resource control configuration within the estimated latency.

[0319] According to an example embodiment, determining whether the user equipment is capable of processing the radio resource control configuration before receiving the cell handover command, or estimating the latency for processing the radio resource control configuration includes at least one of the following: determining at least one change required for a media access control configuration, determining at least one change required for a radio link control configuration, determining at least one change required for a packet data convergence protocol configuration, determining at least one change required for a service data adaptation protocol configuration, determining whether radio frequency retuning is required to comply with the cell handover command, determining whether baseband retuning is required to comply with the cell handover command, or determining whether the user equipment is capable of accessing a target access node unit of the handover procedure without a random access channel procedure.

[0320] According to an example embodiment, the method may include: sending an indication of completion of processing of the radio resource control configuration performed by the user equipment to the source distributed node.

[0321] According to an example embodiment, the indication of completion of processing of the radio resource control configuration 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.

[0322] According to an example embodiment, the user equipment capabilities indicate at least one of the following: the user equipment is configured to: perform verification of the syntax symbols of a radio resource control configuration and determine whether the user equipment is capable of processing the radio resource control configuration before receiving a cell handover command, or estimate the latency for processing the radio resource control configuration in response to receiving the radio resource control configuration from a source distributed node; the user equipment is configured to: perform verification of the syntax symbols of the radio resource control configuration in response to receiving the radio resource control configuration from a source distributed node; the user equipment is configured to: process the radio resource control configuration between the transmission of a layer one measurement report and the reception of a cell handover command, the layer one measurement report including an indication of whether the user equipment is capable of processing the radio resource control configuration before receiving the cell handover command; the user equipment is configured to: process the radio resource control configuration before initiating layer one measurements of a handover process; the user equipment is configured to: process the radio resource control configuration after initiating layer one measurements of a handover process; or the user equipment is configured to: initiate determining whether the user equipment is capable of processing the radio resource control configuration or estimating the latency for processing the radio resource control configuration before receiving a cell handover command in response to receiving an indication of a target cell of a handover process from a source distributed node.

[0323] According to an example embodiment, the method may include: determining whether the user equipment is capable of processing the radio resource control configuration or estimating the latency for processing the radio resource control configuration before receiving a cell handover command in response to receiving a request from a source distributed node to prioritize verification, processing, or preparation of a radio resource control configuration.

[0324] A method may include: sending, by an access node, a radio resource control configuration associated with a handover process to a user equipment; receiving, from the user equipment, an indication of whether the user equipment is capable of processing the radio resource control configuration before receiving a cell handover command; and configuring at least one latency value of the handover process based on the indication of whether the user equipment is capable of processing the radio resource control configuration before receiving the cell handover command; and sending a cell handover command of the handover process to the user equipment.

[0325] According to an example embodiment, the handover process includes a layer one or layer two inter-cell mobility process, and wherein the radio resource control configuration includes a layer one or layer two mobility configuration.

[0326] According to an example embodiment, the method may include: receiving, from the user equipment, an indication of an estimated latency for processing the radio resource control configuration performed by the user equipment; and configuring at least one latency value of the handover process based on the estimated latency for processing the radio resource control configuration performed by the user equipment.

[0327] According to an example embodiment, the method may include: receiving an indication of completion of processing of radio resource control configuration performed by a user equipment from the user equipment; and configuring at least one delay value of a handover procedure based on the indication of completion of processing of radio resource control configuration performed by the user equipment.

[0328] According to an example embodiment, the indication of completion of processing of radio resource control configuration is transmitted in a radio resource control reconfiguration complete message, in a media access control control element, in a layer one measurement report, or as an indication of user equipment capabilities.

[0329] According to an example embodiment, the user equipment capabilities indicate at least one of the following: the user equipment is configured to: perform verification of syntax symbols of radio resource control configuration and determine whether the user equipment is capable of processing radio resource control configuration before receiving a cell handover command, or estimate a delay for processing radio resource control configuration in response to receiving radio resource control configuration from a source distributed node of an access node; the user equipment is configured to: perform verification of syntax symbols of radio resource control configuration in response to receiving radio resource control configuration from a source distributed node of an access node; the user equipment is configured to: process radio resource control configuration between transmission of a layer one measurement report and reception of a cell handover command, the layer one measurement report including an indication of whether the user equipment is capable of processing radio resource control configuration before receiving a cell handover command; the user equipment is configured to: process radio resource control configuration before layer one measurement for initiating a handover procedure; the user equipment is configured to: process radio resource control configuration after layer one measurement for initiating a handover procedure; or the user equipment is configured to: initiate determination of whether the user equipment is capable of processing radio resource control configuration before receiving a cell handover command or estimate a delay for processing radio resource control configuration in response to receiving an indication of a target cell of a handover procedure from a source distributed node of an access node.

[0330] According to an example embodiment, the method may include: sending a request to the user equipment to prioritize verification, processing, or preparation of radio resource control configuration.

[0331] Any range or device value given herein may be extended or altered without losing the desired effect. Additionally, unless explicitly prohibited, any embodiment may be combined with another embodiment.

[0332] Although the subject matter has been described in language specific to structural features and / or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the above specific features or acts. Rather, the above specific features and acts are disclosed as example implementations of the claims, and other equivalent features and acts are intended to be within the scope of the claims.

[0333] It should be understood that the above benefits and advantages may relate to one embodiment or several embodiments. An embodiment is not limited to an embodiment that solves any or all of the stated problems, nor to an embodiment having any or all of the stated benefits and advantages. It should also be understood that the reference to “an” item may mean one or more of these items.

[0334] The steps or operations of the methods described herein may be performed in any suitable order, or simultaneously where appropriate. In addition, individual blocks may be deleted from any method without departing from the scope of the subject matter described herein. Aspects of any of the above example embodiments may be combined with aspects of any of the other above example embodiments to form additional example embodiments without losing the desired effects.

[0335] The term “comprising” is used herein to mean including the identified method, block, or element, but such a block or element does not include an exclusive list, and a method or apparatus may contain additional blocks or elements.

[0336] As used herein, “at least one of the following: <list of two or more elements>” and “at least one of <list of two or more elements>” and similar phrases (where the list of two or more elements is joined by “and” or “or”) mean at least any one of these elements, or at least any two or more of these elements, or at least all of these elements.

[0337] Although a subject may be referred to as a “first” or “second” subject, this does not necessarily denote any order or importance of the subject. Instead, such an attribute may be used only to distinguish the subject.

[0338] As used in this application, the term “circuitry” may refer to one or more or all of the following: (a) a pure hardware circuit implementation (such as an implementation only in analog and / or digital circuitry), and (b) a combination of hardware circuits and software, such as, where applicable: (i) a combination of (one or more) analog and / or digital hardware circuits and software / firmware, and (ii) any portion of (one or more) hardware processors (including (one or more) digital signal processors), software, and (one or more) memories that work together to cause a device (such as a mobile phone or a server) to perform various functions), and (c) (one or more) hardware circuits and / or (one or more) processors, such as (one or more) microprocessors or a portion of (one or more) microprocessors, which require software (e.g., firmware) to operate, but where software may be absent when not needed for operation. This definition of circuitry applies to all uses of the term in this application, including in any claims.

[0339] As another example, as used in this application, the term circuitry also encompasses implementations that are only hardware circuits or processors (or multiple processors) or a portion of a hardware circuit or processor and their attendant software and / or firmware. For example, if applicable to a particular claim element, the term circuitry also encompasses a baseband integrated circuit or a processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0340] It should be understood that the above description is given by way of example only, and that various modifications may be made by those skilled in the art. The foregoing specification, examples, and data provide a complete description of the structure and use of the exemplary embodiments. Although the various embodiments have been described above with a certain degree of clarity or with reference to one or more individual embodiments, many modifications may be made to the disclosed embodiments without departing from the scope of this specification.

Claims

1. A method, comprising: 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; Determining whether the user equipment is capable of preprocessing at least a part of the radio resource control (RRC) reconfiguration message associated with layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) before receiving a cell handover command for performing a cell handover; Performing preprocessing of at least a part of the L1 / L2 triggered mobility (LTM) related part of the received RRC reconfiguration message; And Sending a message to a network node of a radio access network to which the user equipment is connected, the message including: an indication related to a preprocessing part of the L1 / L2 triggered mobility (LTM) related part of the radio resource control reconfiguration message before the receiving of the cell handover command.

2. The method according to claim 1, wherein the network node is a central node of the radio access network, and the message sent to the central node is an RRC reconfiguration complete message, and the RRC reconfiguration complete message includes: An LTM indication indicating a status of preprocessing of LTM preparation operations, in particular an indication of whether at least one of the following has been performed: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

3. The apparatus according to 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 L2 message, in particular a Media Access Control (MAC) Control Element (CE) message, the L2 message comprising: An LTM indication indicating a status of preprocessing of LTM preparation operations, in particular an indication of whether at least one of the following has been performed: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

4. The apparatus according to 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, the L1 measurement report message including: An LTM indication indicating a status of preprocessing of LTM preparation operations, in particular an indication of whether at least one of the following has been performed: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

5. The method according to any one of the preceding claims, wherein the indication related to the preprocessing section comprises: An indication related to a remaining LTM execution time delay.

6. A method, comprising: 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 preprocessing at least a part of the L1 / L2 triggered mobility (LTM) related part of the received RRC message, Determining whether the user equipment is capable of preprocessing the indicated at least a part of the radio resource control reconfiguration message associated with layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) before receiving a cell handover command for performing a cell handover, and Performing preprocessing of the indicated at least a part of the L1 / L2 triggered mobility (LTM) related part of the received RRC message.

7. The method according to any one of the preceding claims, further comprising: After the performed preprocessing ends, sending an L1 measurement report message to a network node of a radio access network to which the user equipment is connected.

8. The method according to any one of the preceding claims, further comprising: In response to receiving an L2 message, in particular a MAC CE message, including the cell handover command, process the unpreprocessed layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the received RRC reconfiguration message, extract the target cell information to be switched to from the cell handover command, and perform a random access procedure towards the target cell.

9. A method, comprising: Establishing, by a user equipment (UE), a connection towards a network node of a radio access network; Sending, by the UE, a UE capability indication towards the network node, the UE capability indication being related to the capability of supporting layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) operations and being related to the support of at least a part of a radio resource control reconfiguration message related to layer 1 / layer 2 (L1 / L2) triggered mobility (LTE) before receiving a cell handover command for performing a cell handover; Receiving, by the user equipment, a radio resource control (RRC) reconfiguration message associated with a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) process; Performing preprocessing of at least a part of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the received RRC message.

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

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

12. The method according to any one of the preceding claims, wherein the preprocessing of at least a part of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the received RRC reconfiguration message comprises preprocessing of at least one of the following: Abstract Syntax Notation One (ASN.1) verification and operations related to LTM RRC configuration evaluation.

13. A method, comprising: Sending, 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) process to a user equipment; Receiving, from a user equipment connected to the radio access network, a message, the message including: an indication related to a preprocessing part of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the radio resource control reconfiguration message before receiving a cell handover command; And Configuring, based on the indication related to the preprocessing part of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the radio resource control reconfiguration message performed by the user equipment, at least one delay value for the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) process for the user equipment.

14. The method according to claim 13, wherein the network node is a central node of the radio access network, and the message received by the central node is an RRC reconfiguration complete message, the RRC reconfiguration complete message comprising: An LTM indication indicating the status of preprocessing for preparing the LTM operation, in particular an indication of whether at least one of the following has been performed: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

15. The apparatus according to 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 L2 message, in particular a Media Access Control (MAC) Control Element (CE) message, the L2 message comprising: An LTM indication indicating the status of preprocessing for preparing the LTM operation, in particular an indication of whether at least one of the following has been performed: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

16. The apparatus according to 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, and the L1 measurement report message includes: An LTM indication indicating the status of preprocessing for preparing the LTM operation, in particular an indication of whether at least one of the following has been performed: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

17. The method according to any one of claims 13 to 16, wherein the indication related to the preprocessing part comprises: An indication related to the remaining LTM execution time delay.

18. A method, comprising: Sending, by a network node, a Radio Resource Control (RRC) reconfiguration message associated with a Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) procedure to a user equipment, the RRC reconfiguration message including: instructions for preprocessing at least a part of the L1 / L2 Triggered Mobility (LTM)-related part of the RRC message.

19. A method, comprising: Establishing, by a network node of a radio access network, a connection with a user equipment (UE); Receiving, from the UE, a UE capability indication related to the capability of supporting a Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) procedure and related to the support for preprocessing at least a part of a Radio Resource Control reconfiguration message related to Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTE) before receiving a cell handover command for performing a cell handover; And Configuring, based on the indication related to the preprocessing part of the L1 / L2 Triggered Mobility (LTM)-related part of the Radio Resource Control reconfiguration message performed by the user equipment, at least one delay value for the Layer 1 / Layer 2 (L1 / L2) Triggered Mobility (LTM) procedure for the user equipment.

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

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

22. The method according to any one of claims 13 to 19, wherein the preprocessing of the at least a part of the L1 / L2 Triggered Mobility (LTM)-related part of the received RRC reconfiguration message includes preprocessing of at least one of the following: Abstract Syntax Notation One (ASN.1) verification, and operations related to LTM RRC configuration evaluation.

23. An apparatus, comprising components for performing the method according to any one of claims 1 to 22.

24. A computer program comprising instructions which, when executed by a device, cause the device to perform the method according to any one of claims 1 to 22.

25. A user equipment UE comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the UE to at least: receive, by the user equipment, a radio resource control (RRC) reconfiguration message associated with a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) procedure; determine whether the user equipment is capable of preprocessing at least a part of the radio resource control (RRC) reconfiguration message associated with layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) before receiving a cell handover command for performing a cell handover; perform preprocessing of at least a part of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the received RRC reconfiguration message; and send a message towards a network node of a radio access network to which the user equipment is connected, the message comprising: an indication related to a preprocessing part of the layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) related part of the radio resource control (RRC) reconfiguration message before the reception of the cell handover command.

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