Controlling timing advance acquisition

Abstract

The present disclosure relates to source-distributed unit (S-DU) controlled timing advance (TA) acquisition. Specifically, it proposes a solution that enables the network to know whether the TA of the S-DU can be used when the UE of the S-DU or source cell needs to perform a handover to the T-DU or target cell. Specifically, the S-DU determines whether the TA value of the S-DU is the same as the TA value of the T-DU. If the S-DU and the T-DU share the same TA value, the S-DU informs the CU of the S-DU that the S-DU and the T-DU share the same TA value. The CU informs the T-DU to release the resource for acquiring the TA value. The S-DU does not trigger the UE to obtain the TA of the T-DU. In this way, it avoids the interruption of the UE side for each unnecessary TA acquisition and performance degradation.

Description

Technical Field

[0001] Various exemplary embodiments of this disclosure generally relate to the telecommunications field, and more particularly to methods, apparatuses, devices, and computer-readable storage media for obtaining timing advances. Background Technology

[0002] When a User Equipment (UE) moves from the coverage area of ​​one cell to another, a serving cell change needs to be performed at some point. Currently, serving cell changes are triggered by Layer 3 (L3) measurements and completed by downlink Radio Resource Control (RRC) signaling, specifically, an RRC reconfiguration message with synchronization for changes to the primary cell (PCell) and primary / secondary cell (PSCell), and, where applicable, the release and addition of secondary cells (SCell). However, the current process is not optimal. Summary of the Invention

[0003] In a first aspect of this disclosure, a source distributed unit is provided. The source distributed unit includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the source distributed unit to: determine whether a timing advance value between a source cell and a terminal device of the source distributed unit is the same as a timing advance value between a target cell and a terminal device of a target distributed unit, wherein a potential handover between the source distributed unit and the target distributed unit and the terminal device is associated; and based on the determination that the timing advance value is the same as the timing advance value between the target cell and the terminal device, send first information to a central unit of the source distributed unit, the first information indicating that the source cell and the target cell share the same timing advance value.

[0004] In a second aspect of this disclosure, a central unit is provided. The central unit includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the central unit to: receive first information from a source distributed unit of the central unit, the first information indicating that a source cell of the source distributed unit and a target cell of a target distributed unit share the same timing advance value, wherein the source distributed unit and the target distributed unit are associated with a potential handover of a terminal device.

[0005] In a third aspect of this disclosure, a target distributed unit is provided. The target distributed unit includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the target distributed unit to: receive an instruction from a central unit of the target distributed unit for releasing a timing acquisition resource at the target distributed unit, wherein the target distributed unit is associated with a potential handover of a terminal device; and release the timing acquisition resource based on the instruction.

[0006] In a fourth aspect of this disclosure, a source distributed unit is provided. The source distributed unit includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the source distributed unit to: receive from a central unit of the source distributed unit an indication of a potential handover of a terminal device from a source cell of the source distributed unit to a target cell of a target distributed unit; determine whether a timing advance value between the source cell and the terminal device can be considered to be the same as a timing advance value between the target cell and the terminal device; and, based on the determination that the distributed unit cannot consider the timing advance value to be the same as a timing advance value between the target cell and the terminal device, trigger the terminal device to acquire a timing advance value for the target cell.

[0007] In a fifth aspect of this disclosure, a central unit is provided. The central unit includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the central unit to: obtain a predetermined criterion, which can be used to determine whether a timing advance value between a terminal device and a first cell is the same as a timing advance value between the terminal device and a second cell; send a first message indicating the predetermined criterion to a source distributed unit; and send a second message indicating the predetermined criterion to a target distributed unit or the central unit of the target distributed unit, wherein the source distributed unit and the target distributed unit are associated with a potential handover of the terminal device.

[0008] In a sixth aspect of this disclosure, a method is provided. The method includes: determining at a source distributed unit whether a timing advance value between a source cell and a terminal device in the source distributed unit is the same as a timing advance value between a target cell and a terminal device in a target distributed unit, wherein potential handovers between the source distributed unit and the target distributed unit and the terminal device are associated; and based on the determination that the timing advance value is the same as the timing advance value between the target cell and the terminal device, sending first information to a central unit of the source distributed unit, the first information indicating that the source cell and the target cell share the same timing advance value.

[0009] In a seventh aspect of this disclosure, a method is provided. The method includes: receiving first information at a central unit and from a source distributed unit of the central unit, the first information indicating that a source cell of the source distributed unit and a target cell of a target distributed unit share the same timing advance value, wherein the source distributed unit and the target distributed unit are associated with a potential handover of a terminal device.

[0010] In an eighth aspect of this disclosure, a method is provided. The method includes: receiving an instruction from a central unit of a target distributed unit for releasing a timing acquisition resource at the target distributed unit, wherein the target distributed unit is associated with a potential handover of a terminal device; and releasing the timing acquisition resource based on the instruction.

[0011] In a ninth aspect of this disclosure, a method is provided. The method includes: receiving, at a source distributed unit and from a central unit of the source distributed unit, an indication of a potential handover by a terminal device from a source cell of the source distributed unit to a target cell of a target distributed unit; determining whether a timing advance value between the source cell and the terminal device can be considered the same as a timing advance value between the target cell and the terminal device; and, based on the determination that the distributed unit cannot consider the timing advance value to be the same as a timing advance value between the target cell and the terminal device, triggering the terminal device to acquire a timing advance value for the target cell.

[0012] In a tenth aspect of this disclosure, a method is provided. The method includes: obtaining a predetermined criterion at a central unit, the predetermined criterion being usable for determining whether a timing advance value between a terminal device and a first cell is the same as a timing advance value between the terminal device and a second cell; sending a first message indicating the predetermined criterion to a source distributed unit; and sending a second message indicating the predetermined criterion to a target distributed unit or the central unit of the target distributed unit, wherein the source distributed unit and the target distributed unit are associated with a potential handover of the terminal device.

[0013] In the eleventh aspect of this disclosure, a first apparatus is provided. The first apparatus includes: a component for determining whether a timing advance value between a source cell of a source distributed unit and a terminal device is the same as a timing advance value between a target cell of a target distributed unit and a terminal device, wherein potential handovers between the source distributed unit and the target distributed unit and the terminal device are associated; and a component for sending first information to a central unit of the source distributed unit based on the determination that the timing advance value is the same as the timing advance value between the target cell and the terminal device, the first information indicating that the source cell and the target cell share the same timing advance value.

[0014] In a twelfth aspect of this disclosure, a second apparatus is provided. The second apparatus includes components for receiving first information from a source distributed unit of a central unit, the first information indicating that a source cell of the source distributed unit and a target cell of a target distributed unit share the same timing advance value, wherein the source distributed unit and the target distributed unit are associated with a potential handover of a terminal device.

[0015] In a thirteenth aspect of this disclosure, a third apparatus is provided. The third apparatus includes: components for receiving an instruction from a central unit of a target distributed unit, the instruction being for releasing a timing acquisition resource at the target distributed unit, wherein the target distributed unit is associated with a potential handover of a terminal device; and components for releasing the timing acquisition resource based on the instruction.

[0016] In a fourteenth aspect of this disclosure, a first apparatus is provided. The first apparatus includes: components for receiving from a central unit of a source distributed unit an indication of a potential handover of a terminal device from a source cell of the source distributed unit to a target cell of a target distributed unit; components for determining whether a timing advance value between the source cell and the terminal device can be considered the same as a timing advance value between the target cell and the terminal device; and components for triggering the terminal device to acquire a timing advance value for the target cell based on the determination that the distributed unit cannot consider the timing advance value to be the same as the timing advance value between the target cell and the terminal device. In a fifteenth aspect of this disclosure, a second apparatus is provided. The second apparatus includes: components for obtaining a predetermined criterion, which can be used to determine whether a timing advance value between the terminal device and a first cell is the same as a timing advance value between the terminal device and a second cell; components for sending a first message indicating the predetermined criterion to a source distributed unit; and components for sending a second message indicating the predetermined criterion to a target distributed unit or a central unit of the target distributed unit, wherein the potential handover of the source distributed unit and the target distributed unit is associated with the terminal device.

[0017] In a sixteenth aspect of this disclosure, a computer-readable medium is provided. The computer-readable medium includes instructions stored thereon for causing a device to perform at least the method according to a sixth, seventh, eighth, ninth, or tenth aspect.

[0018] It should be understood that the summary portion is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0019] Some exemplary embodiments will now be described with reference to the accompanying drawings, in which: Figure 1 An example communication environment in which example embodiments of this disclosure may be implemented is shown; Figure 2 A flowchart illustrating the collection of timing advance values ​​according to an example embodiment of the present disclosure is shown; Figure 3 A flowchart illustrating the provision of a predetermined threshold according to an example embodiment of this disclosure is shown; Figure 4AA flowchart illustrating the collection of timing advance values ​​in a central unit (CU) according to an example embodiment of the present disclosure is shown; Figure 4B A flowchart illustrating the collection of timing advance values ​​between CUs according to an example embodiment of the present disclosure is shown; Figure 5 A flowchart of a handover without timing advance acquisition is shown according to an example embodiment of the present disclosure; Figure 6 A flowchart illustrating the provision of timing advance values ​​according to an example embodiment of the present disclosure is shown; Figure 7A A flowchart is shown for a handover in a CU scene without timing advance acquisition, according to an example embodiment of the present disclosure; Figure 7B A flowchart is shown for a handover in an inter-CU scenario without timing advance acquisition, according to an example embodiment of the present disclosure; Figure 8A A flowchart is shown for a handover in a CU scene without timing advance acquisition, according to other exemplary embodiments of the present disclosure; Figure 8B A flowchart is shown for a handover in an inter-CU scenario without timing advance acquisition, according to other exemplary embodiments of the present disclosure; Figure 9 A flowchart illustrating a method implemented at a source distributed unit (DU) according to some example embodiments of the present disclosure is shown; Figure 10 A flowchart is shown illustrating a method implemented at a CU according to some example embodiments of this disclosure; Figure 11 A flowchart is shown illustrating a method implemented at a target DU according to some example embodiments of the present disclosure; Figure 12 A flowchart is shown illustrating a method implemented at a terminal device according to some example embodiments of the present disclosure; Figure 13 A flowchart is shown illustrating a method implemented at a source DU device according to some example embodiments of the present disclosure; Figure 14 A flowchart is shown illustrating a method implemented at a CU according to some example embodiments of this disclosure; Figure 15 A simplified block diagram of a device suitable for implementing example embodiments of the present disclosure is shown; and Figure 16 A block diagram of an example computer-readable medium according to some example embodiments of the present disclosure is shown.

[0020] In all the accompanying drawings, the same or similar reference numerals denote the same or similar elements. Detailed Implementation

[0021] The principles of this disclosure will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are described for illustrative purposes only and to assist those skilled in the art in understanding and implementing this disclosure, and do not imply any limitation on the scope of this disclosure. The embodiments described herein can be implemented in various ways other than those described below.

[0022] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0023] References to "an embodiment," "embodiment," "example embodiment," etc., in this disclosure indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment must include that particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Additionally, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is believed that incorporating other embodiments, whether explicitly described or not, to affect such a feature, structure, or characteristic is within the knowledge of those skilled in the art.

[0024] It should be understood that although terms such as "first," "second," etc., preceding nouns (or similar terms) may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another, and they do not restrict the order of the nouns (or similar terms). For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element, without departing from the scope of the exemplary embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0025] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where a list of two or more elements is combined with “and” or “or”, means at least one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0026] As used herein, unless explicitly stated otherwise, the execution step “in response to A” does not indicate that the step is performed immediately after “A” occurs, and may include one or more intermediate steps.

[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the terms “comprising,” “including,” “having,” “possessing,” “containing,” and / or “covering” as used herein specify the presence of stated features, elements, and / or components, etc., but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0028] As used in this application, the term "circuit" may refer to one or more or all of the following: (a) Hardware circuit implementation only (e.g., implemented with purely analog and / or digital circuits) and (b) A combination of hardware circuitry and software, such as (if applicable): (i) A combination of (multiple) analog and / or digital hardware circuits and software / firmware, and (ii) Any part of a hardware processor having software (including (multiple) digital signal processors, software, and (multiple) memories, which work together to enable a device (such as a mobile phone or server) to perform various functions), and (c) The operation requires software (e.g., firmware) for the operation of (multiple) hardware circuits and / or (multiple) processors, such as (multiple) microprocessors or a portion thereof, but the software may be absent when the operation does not require the software.

[0029] This definition of "circuit" applies to all uses of the term in this application (including any claims). As another example, as used in this application, the term "circuit" also covers only hardware circuitry or processors (or processors), or a portion of hardware circuitry or processors and their accompanying software and / or firmware implementations. For example, if applicable to a particular claim element, the term "circuit" also covers baseband integrated circuits or processor integrated circuits for mobile devices or similar integrated circuits in servers, cellular network devices, or other computing or networking devices.

[0030] As used herein, the term "communication network" refers to a network that conforms to any suitable communication standard, such as New Radio (NR), Long Term Evolution (LTE), LTE-A Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), etc. Furthermore, communication between terminal devices and network devices in the communication network can be performed according to any suitable generation of communication protocol, including but not limited to first-generation (1G), second-generation (2G), 2.5G, 2.75G, third-generation (3G), fourth-generation (4G), 4.5G, fifth-generation (5G), sixth-generation (6G) communication protocols and / or any other currently known or future-developed protocols. Embodiments of this disclosure can be applied to a variety of communication systems. Given the rapid development of communications, there will certainly be future types of communication technologies and systems that embody the nature of this disclosure. The scope of this disclosure should not be construed as limited to the aforementioned systems.

[0031] As used herein, the term "network device" refers to a node in a communications network through which terminal devices access the network and receive services. Depending on the terminology and technology applied, a network device can refer to a base station (BS) or access point (AP), such as a Node B (NodeB or NB), an evolved Node B (eNodeB or eNB), an NR NB (also known as a gNB), a Remote Radio Unit (RRU), a Radio Head (RH), a Remote Radio Head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low-power node (such as a femtosecond or picosecond), a non-terrestrial network (NTN) or non-terrestrial network device (such as satellite network equipment, low Earth orbit (LEO) satellites, and geostationary Earth orbit (GEO) satellites), an aircraft network device, etc. In some example embodiments, the Radio Access Network (RAN) split architecture includes a centralized unit (CU) and a distributed unit (DU) at the IAB donor node. An IAB node includes: a mobile terminal (IAB-MT) portion that resembles a UE relative to its parent node; and a DU portion of the IAB node that resembles a base station relative to the next-hop IAB node.

[0032] The term "terminal device" refers to any terminal device capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). Terminal devices may include, but are not limited to, mobile phones, cellular phones, smartphones, Voice over IP (VoIP) phones, wireless local loop phones, tablet computers, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback facilities, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEEs), laptop mounted devices (LMEs), USB dongles, smart devices, wireless client equipment (CPEs), Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of industrial and / or automated processing chains), consumer electronics devices, devices operating on commercial and / or industrial wireless networks, etc. The terminal equipment may also correspond to the mobile termination (MT) portion of an IAB node (e.g., a relay node). In the following description, the terms "terminal equipment," "communication equipment," "terminal," "user equipment," and "UE" are used interchangeably.

[0033] As used herein, the terms “resource,” “transmission resource,” “resource block,” “physical resource block” (PRB), “uplink resource,” or “downlink resource” can refer to any resource used to perform communication, such as communication between a terminal device and a network device, including resources in the time domain, frequency domain, spatial domain, code domain, or any other combination of time, frequency, spatial, and / or code domain resources used to enable communication. In the following, unless explicitly stated otherwise, resources in the frequency and time domains will be used as examples of transmission resources used to describe some exemplary embodiments of this disclosure. Note that the exemplary embodiments of this disclosure are equally applicable to other resources in other domains.

[0034] As used herein, the term "Timing Advance (TA)" or "TA Value" can refer to a parameter used to synchronize the transmission timing of a mobile device with the transmission timing of the serving cell in a cellular network. The term "TA Acquisition" as used herein can refer to the process of acquiring / measuring the TA Value. The term "TA Resource" as used herein can refer to the resource used to acquire / measuring the TA Value, such as the Physical Random Access Channel (PRACH) preamble.

[0035] The term "handover" as used herein can refer to a process in communications where a connected call or data session is transferred from one cell to another without disconnecting the session. The term "source cell" as used herein can refer to the currently serving cell during the handover process. The term "target cell" as used herein can refer to the cell to which the UE is handover.

[0036] Network devices / base stations can be divided into two entities: a Central Unit (CU) and a Distributed Unit (DU). The CU provides support for higher layers of the protocol stack, such as Serving Data Adaptation Protocol (SDAP), Packet Data Convergence Protocol (PDCP), and Radio Resource Control (RRC), while the DU provides support for lower layers of the protocol stack, such as Radio Link Control (RLC), Media Access Control (MAC), and the physical layer. One CU can correspond to one or more DUs. The term "source DU (S-DU)" as used herein refers to the DU that provides the source cell. The term "target DU (T-DU)" as used herein refers to the DU that provides the target cell. If the S-DU and T-DU belong to different CUs, the CU of the S-DU can be referred to as the "source CU (S-CU)," and the CU of the T-DU can be referred to as the "target CU (T-CU)." As described above, serving cell changes are triggered by Layer 3 (L3) measurements and completed by downlink radio resource control (RRC) signaling. This involves a complete Layer 2 (L2) and Layer 1 (L1) reset, resulting in longer latency, greater overhead, and longer downtime compared to beam-switching mobility. The goal of L1 / L2 mobility enhancement is to achieve serving cell changes via L1 / L2 signaling to reduce latency, overhead, and downtime.

[0037] In some solutions, a candidate gNB-DU can provide information about the same TA value as the source DU during the L1 / L2 triggered mobility (LTM) configuration phase. However, for the candidate gNB-DU to provide such information, two things must be known in advance: the source cell TA and the target cell TA. Only the source DU knows the source cell TA, so it cannot be assumed that the T-DU knows it. Furthermore, the T-DU does not know the TA value between the UE and the T-DU / cell until the UE sends the PRACH preamble to the T-DU. The UE sends the PRACH preamble to the T-DU after preparation. Considering that at preparation, the T-DU knows neither the S-DU TA nor the T-DU TA.

[0038] In some other solutions, it is proposed to provide TA group (TAG) information for LTM, such as adding a TAG ID that includes the UE context establishment response. The TAG ID only indicates the ID of the TAG to which the cell belongs. However, it does not indicate the TA value itself. Even if the TAG ID is shared along with the TA value, the shared TA value of the S-DU can change over time, and the S-DU / cell TA and T-DU / cell TA can be the same or different when the TA is acquired or executed.

[0039] Furthermore, as agreed, if the T-DU / cell and S-DU / cell share the same TA value, the S-DU will not trigger early TA acquisition for the T-DU / cell. TA is not a cell configuration, but it is a value measured between each UE and the cell; that is, it is the time when the UE sends its signal to the cell. In some cell boundaries, the TA value for the same UE can be the same between two pairs: (1) UE and source cell and (2) UE and target cell. However, the S-DU does not know whether the source cell and target cell share the same TA value because, as mentioned above, it is not a network parameter configuration, but a measurement between each UE and the cell; that is, the S-DU / cell does not know the TA value between the UE and the T-DU / cell. Ultimately, this leads to the S-DU unnecessarily triggering TA acquisition. Ultimately, this leads to interruptions on the UE side for each unnecessary early TA acquisition and results in performance degradation. In addition, each TA acquisition requires UL signaling from the UE to the target cell, as well as signaling in the F1 interface for forwarding the TA value from the T-DU / cell to the S-DU / cell, which results in signaling overhead.

[0040] Furthermore, early TA acquisition is not triggered when the source and target cells share the same TA. Therefore, there is no need to reserve resources required for the early TA acquisition process, as they will not be used. Considering that the CU does not know whether the source and target cells share the same TA value, the CU needs to request and reserve TA acquisition resources at the T-DU. This results in unnecessary resource reservation for early TA acquisition. Additionally, both the S-DU and UE will be configured with early TA acquisition, which unnecessarily leads to additional configuration processing at the receiving node.

[0041] According to an example embodiment of this disclosure, a solution is proposed that enables the network to determine whether the TA of the S-DU can be used when the UE of the S-DU or source cell needs to perform a handover to the T-DU or target cell. Specifically, the S-DU determines whether its TA value is the same as the T-DU's TA value. If the S-DU and T-DU share the same TA value, the S-DU notifies its CU that the S-DU and T-DU share the same TA value. The CU then notifies the T-DU to release the resources used to acquire the TA value. The S-DU does not trigger the UE to acquire the TA for the T-DU. In this way, it avoids interruptions on the UE side for every unnecessary TA acquisition and performance degradation. Furthermore, it saves signaling overhead and resources.

[0042] Figure 1 An example communication environment 100 in which exemplary embodiments of the present disclosure may be implemented is shown. In the communication environment 100, terminal devices 150-1, 150-2, ..., 150-N (collectively referred to as "terminal devices 150") may exist, where N is an integer. Terminal devices 150 are in the currently serving cell 101 (also referred to as "source cell 101") provided by DU 110 (also referred to as "source DU 110"). Candidate target cells that terminal devices 150 may be handoverable to, such as cell 103 (also referred to as "target cell 103") and cell 104. Figure 1 As shown, target cell 103 can be provided by DU 130 (also referred to as "target DU 130"). In some example embodiments, in an intra-CU scenario, source DU 110 and target DU 130 can share or belong to the same CU 120. In some other example embodiments, in an inter-CU scenario, source DU 110 belongs to CU 120 (referred to as "source CU 120" in the inter-CU scenario), and target DU 130 belongs to CU 140 (referred to as "target CU 140" in the inter-CU scenario). The source DU and source CU can form a source base station, and the target DU and target CU can form a target base station for handover of terminal equipment.

[0043] In some example embodiments, the link from source DU 110 or target DU 130 to terminal device 150 is referred to as a downlink (DL), and the link from terminal device 150 to source DU 110 or target DU 130 is referred to as an uplink (UL). In the DL, source DU 110 or target DU 130 is a transmitting (TX) device (or transmitter), and terminal device 150 is a receiving (RX) device (or receiver). In the UL, terminal device 150 is a TX device (or transmitter), and source DU 110 or target DU 130 is an RX device (or receiver).

[0044] Communication in communication environment 100 can be implemented according to any suitable communication protocol(s), including but not limited to cellular communication protocols such as first-generation (1G), second-generation (2G), third-generation (3G), fourth-generation (4G), fifth-generation (5G), and sixth-generation (6G), wireless local network communication protocols such as IEEE 802.11, and / or any other currently known or future-developed protocols. Furthermore, communication can utilize any suitable wireless communication technology, including but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple Access (OFDM), Discrete Fourier Transform Extended OFDM (DFT-s-OFDM), and / or any other currently known or future-developed technologies.

[0045] Exemplary embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. Note that one or more exemplary embodiments described with reference to different drawings may be combined in any suitable manner. Furthermore, one or more exemplary embodiments described with reference to the same drawings may be implemented individually or in combination.

[0046] refer to Figure 2 , Figure 2 Signaling flows 200 according to some embodiments of this disclosure are shown. For discussion purposes, reference will be made to... Figure 1 For example, signaling flow 200 can be discussed using source DU 110 and CU 120. Signaling flow 200 can be implemented in intra-CU scenarios or inter-CU scenarios. Note that... Figure 2 This is merely a brief description of the signaling flow in this disclosure, and details of exemplary embodiments will be described later with reference to other accompanying drawings.

[0047] CU 120 sends (2010) an indication (2010) of a potential handover from source cell 101 to target cell 102 to source DU 110. In other words, source DU 110 receives (2010) an indication (2010) of a potential handover from CU 120.

[0048] Source DU 110 determines (2020) whether it knows whether the TA value between source cell 101 and terminal device 150-1 is the same as the TA value between target cell 102 and terminal device 150-1. In other words, source DU 110 determines (2020) whether it can / is able to assume that the TA value between source cell 101 and terminal device 150-1 is the same as the TA value between target cell 102 and terminal device 150-1. In this case, if source DU 110 does not know (or does not assume) whether the TA value is the same as the TA value between target cell 102 and terminal device 150-1, then source DU 110 triggers (2030) terminal device 150-1 to acquire the TA for target cell 102. Alternatively, if source DU 110 knows that the TA value is different from the TA value between target cell 102 and terminal device 150-1, source DU 110 can also trigger terminal device 150-1 to acquire the TA value for target cell 102. In some other embodiments, if source DU 110 believes that the TA value is the same as the TA value between target cell 102 and terminal device 150-1, source DU 110 can avoid triggering terminal device 150-1 to acquire the TA value for target cell 102.

[0049] Source DU 110 obtains (2040) multiple TA values ​​between target cell 102 and a group of terminal devices served by source cell 101 from CU 120 based on this trigger. For example, source DU 110 may need to perform TA acquisition of target DU 130 multiple times before concluding whether the TAs between any two cells are the same or different. For example, source DU 110 may obtain the TA value between target cell 102 and each of the terminal devices 150. For instance, source DU 110 may obtain the TA value between target cell 102 and terminal device 150-1, the TA value between target cell 102 and terminal device 150-2, ..., the TA value between target cell 102 and terminal device 150-N. Source DU 110 may store (2050) the number of TA values ​​between target cell 102 and the group of terminal devices.

[0050] In some example embodiments, source DU 110 may collect the same number of TA values ​​for each cell pair between source DU 110 and target DU 130. For example, source DU 110 may collect X TA values ​​for a cell pair between source cell 101 and target cell 102, and may also collect X TA values ​​for a cell pair between source cell 101 and target cell 103, where X may be any suitable integer.

[0051] Alternatively, source DU 110 can collect different numbers of TA values ​​for different cell pairs between source DU 110 and target DU 130. For example, source DU 110 can collect X TA values ​​for a cell pair of source cell 101 and target cell 102, and can collect Y TA values ​​for a cell pair of source cell 101 and target cell 103, where X and Y can be different integers. In some embodiments, the number of TA values ​​to be collected can be pre-configured or determined at source DU 110. Alternatively, the number of TA values ​​to be collected can be configured by CU 120.

[0052] Source DU 110 can derive statistics comparing the TA values ​​between source DU 110 and target DU 130 based on the number of TA values ​​collected by source DU 110 for the target cell / target DU. For example, source DU 110 can determine (or assume) that the timing advance value of source cell 101 is the same as the timing advance value of target cell 102 based on the number of timing advance values ​​of target cell 102 satisfying a predetermined criterion. Alternatively, source DU can determine / assume that the TA value of source cell 101 is different from the TA value of target cell 102. The predetermined criterion may include one or more of the following: a threshold for the required number of TA acquisitions, or another threshold representing the hit rate or accuracy of shared TA values ​​among all collected TA values, or a combination of the above thresholds.

[0053] In some example embodiments, a predetermined criterion may require that a predetermined number of TA values ​​of target cell 102 be the same as the TA values ​​between source cell 101 and terminal device 150-1. In this case, in some example embodiments, if source DU 110 collects a number X of TA values ​​for target cell 102, and the number of TA values ​​equal to the TA value of source cell 101 is equal to or greater than a number A (i.e., a predetermined number), then source DU 110 can determine that source cell 101 and target cell 102 share the same TA values, where A is an integer less than or equal to X. For example, if source DU 110 collects 10 TA values ​​for target cell 102, and the number of TA values ​​in target cell 102 that are substantially equal to the TA value of source cell 101 is equal to or greater than 8, then source DU 110 can determine that source cell 101 and target cell 102 share the same TA values. Alternatively, if the number X of TA values ​​collected by source DU 110 from target cell 102 is less than the number A, then source DU 110 can determine that source cell 101 and target cell 102 do not share the same TA values. For example, if source DU 110 collects 10 TA values ​​from target cell 102, and 7 of the 10 TA values ​​have the same value as the TA value of the source cell, then source DU 110 can determine that source cell 101 and target cell 102 do not share the same TA values. In some embodiments, the number A can be pre-configured or determined at source DU 110. Alternatively, the number A can be configured by CU 120. Alternatively or additionally, the pre-determined criteria may include a predetermined ratio of TA values ​​of target cell 102 being the same as the TA values ​​between source cell 101 and terminal device 150-1. For example, if source DU 110 collects X numbers of TA values ​​for target cell 102, and B% (i.e., a predetermined ratio) of the collected TA values ​​is equal to the TA value of source cell 101, then source DU 110 can determine that source cell 101 and target cell 102 share the same TA value. Alternatively, if less than B% of the collected TA values ​​are equal to the TA value for source cell 101, then source DU 110 can determine that source cell 101 and target cell 102 do not share the same TA value.

[0054] In some other example embodiments, the source DU 110 may determine whether the source DU 110 does not know the TA value of the source cell is the same as the TA value between the target cell 102 and the terminal device 150-1 based on the fact that the number of times the TA acquisition is triggered is less than a predetermined number.

[0055] In some example embodiments, the predetermined criteria can be pre-configured at the source DU 110. For example, the predetermined criteria can be default parameters specified for the target DU 130.

[0056] Alternatively, the predefined criteria can be configured by CU 120. For example, source DU 110 can receive predefined criteria from CU 120. Figure 3 As shown, CU 120 can send a first message (3020) including predetermined criteria to source DU 110. CU 120 can send a second message (3030) including predetermined criteria to target DU 130. For example, predetermined criteria can be sent in an F1 establishment request for both source DU 110 and target DU 130. Source DU 110 can send an F1 establishment response (3040) to CU 120. Target DU 130 can send an F1 establishment response (3050) to CU 120.

[0057] In some example embodiments, CU 120 may determine a predetermined criterion for determining whether the TA value between terminal device 150-1 and a first cell (i.e., source cell 101 in this embodiment) is the same as the timing advance between terminal device 150-1 and a second cell (i.e., target cell 102 in this embodiment). For example, CU 120 may determine the predetermined criterion based on one or more of the following: propagation attributes for mobility, or transmission failure, etc. Note that the predetermined criterion may be determined based on any suitable characteristic. CU 120 may update the predetermined criteria for one or more DUs via a gNB DU configuration update procedure. Alternatively, core network device 310 (e.g., Operation, Administration and Maintenance (OAM)) may provide the predetermined criteria to CU 120.

[0058] In some example embodiments, the predetermined criterion is a global parameter for all target DUs. For example, the predetermined criterion may be the same for all target DUs associated with CU120. Alternatively, the predetermined criterion may be a DU pair parameter. For example, the predetermined criterion may be the same for DU pairs associated with CU120. In some other example embodiments, the predetermined criterion may be a parameter for each DU. For example, the predetermined criterion may be different for different DUs associated with CU120. In some other example embodiments, the predetermined criterion may be a parameter for each cell pair. For example, the predetermined criterion for a cell pair including source cell 101 and target cell 102 may be different from the predetermined criterion for a cell pair including source cell 101 and target cell 103.

[0059] Figure 4A A signaling flow 400 for collecting timing advance values ​​within a CU according to an example embodiment of the present disclosure is illustrated. For purposes of discussion, reference will be made, for example, to a source DU 110, a target DU 130, a CU 120, and a terminal device 150-1. Figure 1 Discuss signaling flow 400.

[0060] Terminal device 150-1 may send (4001) an L3 measurement report to source DU 110, including L3 measurements of source cell 101 and neighboring cells (e.g., cells 102 and 103). The L3 measurement report means that the L3 values ​​at terminal device 150-1 are filtered and then reported. Filtering is performed to remove the effects of rapid fading and ignore short-term changes. While L1 measurements can be collected more frequently, L3 measurements can be reported over a longer configuration period. Source DU 110 may forward (4002) the L3 measurement report to CU 120.

[0061] CU 120 can perform (4003) handover (HO) decisions. For example, CU 120 can decide to prepare target DU 130 or target cell 102 for handover of terminal equipment 150-1. CU 120 can also decide to prepare the random access channel (RACH) configuration for the physical downlink control channel (PDCCH) commands obtained by the TA for the prepared cell (i.e., target cell 102).

[0062] CU 120 may send a (4004) UE context establishment request to target DU 130 to prepare for handover. CU 120 may also request target DU 130 to provide TA acquisition configuration. For example, the UE context establishment request may include a TA acquisition configuration request. Target DU 130 may send a (4005) UE context establishment response to CU 120. For example, target DU 130 may provide TA acquisition configuration and handover configuration in the UE context establishment response.

[0063] CU 120 can send a (4006) UE context modification request to source DU 110. For example, CU 120 can notify source DU 110 or cell 101 of handover preparation (i.e., indication of potential handover) and request source DU 110 or cell 101 to provide further configuration required for LTM handover preparation and information about the ready cell (i.e., cell 102).

[0064] In some example embodiments, source DU 110 can determine (4006.5) whether source DU 110 knows whether source cell 101 and target cell 102 share the same TA value. For example, source DU 110 can check whether the TA relationship between cell 101 and cell 102 is known, that is, whether the TA value of source cell 101 is the same as the TA value of target cell 102 (or can be considered to be the same as the TA value of target cell 102). For example, source DU 110 can base its determination on the above-described combination of... Figure 2 and Figure 3The decision is made based on the previously observed number of TA acquisitions (4006.5). For example, if a TA acquisition has never been triggered before, or if a TA acquisition has been triggered once or more, but the number of acquired TA values ​​of the target cell that are substantially the same as the TA value of the source cell is less than a predetermined number, it can be determined that the TA values ​​cannot be considered the same. The source DU 110 can send a (4007) UE context modification response.

[0065] CU 120 can generate (4008) a handover configuration that includes measurement configuration and cell configuration. The handover configuration may also include the TA acquisition configuration for the target DU 130 or the target cell 102. CU 120 can send (4009) the handover configuration, including the TA acquisition configuration, to the source DU 110 in an RRC message.

[0066] Alternatively, instead of determining (4006.5) whether source DU 110 knows whether source cell 101 and target cell 102 share the same TA value after 4006, source DU 110 can determine (4010) whether source DU 110 knows whether source cell 101 and target cell 102 share the same TA value in step 4010. Source DU 110 can store (4011) TA acquisition configuration.

[0067] Source DU 110 can forward (4012) a handover configuration, including TA acquisition configuration, to terminal device 150-1 in an RRC message. After receiving the handover configuration in the RRC configuration, terminal device 150-1 can send an RRC reconfiguration complete message (4013) to source DU 110. Source DU 110 can forward an RRC reconfiguration complete message (4014) to CU 120.

[0068] Terminal device 150-1 may send (4015) an L1 measurement report including one or more candidate cells to source DU 110. For example, the L1 measurement report may indicate the reference signal received power (RSRP) value.

[0069] Since the source DU 110 does not know whether the source cell 101 and the target cell 102 share the same TA value, the source DU 110 can trigger the TA acquisition of the (4016) Physical Downlink Control Channel (PDCCH) command.

[0070] Terminal device 150-1 may send a preamble (e.g., a PRACH preamble) to target DU 130. Target DU 130 may evaluate (4018) the TA value between target DU 130 and terminal device 150-1 based on the preamble. Target DU 130 may notify (4019) the evaluated TA value to source DU 110 via CU 120. Source DU 110 may store (4020) the received TA value of target cell 102. In this way, the source DU can understand whether the source cell and target cell share the same TA value based on the stored TA values ​​of the target cell(s), which facilitates handover without requiring TA acquisition at a later stage.

[0071] Terminal device 150-1 can send (4021) an L1 measurement report about target cell 102 to source DU 110. Source DU 110 can trigger (4022) a cell change indicating the TA value of target cell 102. For example, source DU 110 can send (4022) a Media Access Control Element (MAC CE) to terminal device 150-1 to trigger a cell change (i.e., a change to target cell 102). The MAC CE may also include the TA value of target cell 102. When performing HO, terminal device 150-1 can perform (4023) RACH-free access to target DU 130 by using the TA value provided in the MAC CE. In this way, it can reduce the latency of accessing the target DU and avoid UE interruption.

[0072] Figure 4B A signaling stream 400' for collecting timing advance values ​​between CUs is illustrated according to an example embodiment of this disclosure. Reference will be made to this stream for discussion purposes. Figure 1 For example, signaling flow 400' can be discussed using source DU 110, target DU 130, CU 120, CU 140 and terminal device 150-1.

[0073] Terminal device 150-1 can send (4001') an L3 measurement report to source DU 110, including L3 measurements of source cell 101 and neighboring cells (e.g., cells 102 and 103). The L3 measurement report means that the L3 values ​​at terminal device 150-1 are filtered and then reported. Filtering is performed to remove the effects of rapid fading and ignore short-term changes. Although L1 measurements can be collected more frequently, L3 measurements can be reported at longer configuration intervals. Source DU 110 can forward (4002') the L3 measurement report to CU 120.

[0074] CU 120 can perform (4003') handover (HO) decisions. For example, CU 120 can decide to prepare target DU 130 or target cell 102 for handover of terminal equipment 150-1. CU 120 can also decide to prepare the random access channel (RACH) configuration for the physical downlink control channel (PDCCH) commands obtained by the TA for the prepared cell (i.e., target cell 102). CU 120 can send a (4003.5) handover request to CU 140.

[0075] CU 140 can send a (4004') UE context establishment request to target DU 130 to prepare for handover. CU 140 can also request target DU 130 to provide TA acquisition configuration. For example, the UE context establishment request may include a TA acquisition configuration request. Target DU 130 can send a (4005') UE context establishment response to CU 140. For example, target DU 130 may provide TA acquisition configuration and handover configuration in the UE context establishment response. CU 140 can send a (4005.5) handover request confirmation to CU 120.

[0076] CU 120 can send a (4006') UE context modification request to source DU 110. For example, CU 120 can notify source DU 110 or cell 101 of handover preparation (i.e., indication of potential handover) and request source DU 110 or cell 101 to provide further configuration required for LTM handover preparation and information about the ready cell (i.e., cell 102).

[0077] In some example embodiments, source DU 110 can determine (4006.5') whether source DU 110 knows whether source cell 101 and target cell 102 share the same TA value. For example, source DU 110 can check whether the TA relationship between cell 101 and cell 102 is known, as described above. Figure 2 and Figure 3 As explained. For example, if TA acquisition has never been triggered before, or if TA acquisition has been triggered once or more, but the number of acquired TA values ​​of the target cell that are substantially the same as the TA value of the source cell is less than a predetermined number, it can be determined that the TA values ​​cannot be considered the same. The source DU 110 can send a (4007') UE context modification response.

[0078] CU 120 can generate (4008') a handover configuration that includes measurement configuration and cell configuration. The handover configuration may also include the TA acquisition configuration for the target DU 130 or the target cell 102. CU 120 can send (4009') a handover configuration including the TA acquisition configuration to the source DU 110 in an RRC message.

[0079] Alternatively, it is not necessary to determine whether source DU 110 knows whether source cell 101 and target cell 102 share the same TA value after 4006 (4006). Source DU 110 can determine whether source DU 110 knows whether source cell 101 and target cell 102 share the same TA value (4010'). Source DU 110 can store the TA retrieval configuration (4011').

[0080] Source DU 110 can forward (4012') a handover configuration, including TA acquisition configuration, to terminal device 150-1 in an RRC message. After receiving the handover configuration in the RRC configuration, terminal device 150-1 can send an RRC reconfiguration complete message (4013') to source DU 110. Source DU 110 can forward an RRC reconfiguration complete message (4014') to CU 120.

[0081] Terminal device 150-1 may send (4015') an L1 measurement report including one or more candidate cells to source DU 110. For example, the L1 measurement report may indicate the reference signal received power (RSRP) value.

[0082] Since the source DU 110 does not know whether the source cell 101 and the target cell 102 share the same TA value, the source DU 110 can trigger the TA acquisition of the (4016′) Physical Downlink Control Channel (PDCCH) command.

[0083] Terminal device 150-1 can send a preamble (e.g., a Physical Random Access Channel (PRACH) preamble) to target DU 130. Target DU 130 can evaluate (4018') the TA value between target DU 130 and terminal device 150-1 based on the preamble. Target DU 130 can notify (4019') the evaluated TA value to source DU 110 via CU 120 and CU 140. Source DU 110 can store (4020') the received TA value of target cell 102. In this way, the source DU can understand whether the source cell and target cell share the same TA value based on the stored TA values ​​of the target cell(s), which facilitates handover without requiring TA acquisition at a later stage.

[0084] Terminal device 150-1 can send (4021') an L1 measurement report about target cell 102 to source DU 110. Source DU 110 can trigger (4022') a cell change indicating the TA value of target cell 102. For example, source DU 110 can send (4022') a Media Access Control (MAC) CE to terminal device 150-1 to trigger a cell change (i.e., a change to target cell 102). The MAC CE may also include the TA value of target cell 102. When performing HO, terminal device 150-1 can perform (4023') RACH-free access to target DU 130 by using the TA value provided in the MAC CE. In this way, it can reduce the latency of accessing the target DU and avoid UE interruption.

[0085] refer to Figure 5 , Figure 5 Signaling flow 500 according to some embodiments of the present disclosure is illustrated. For purposes of discussion, reference will be made, for example, by using source DU 110, CU 120, target DU 130, and terminal device 150-1. Figure 1 Let's discuss signaling flow 500. Signaling flow 500 can be implemented in intra-CU scenarios or inter-CU scenarios. Note that... Figure 5 This is merely a brief description of the signaling flow in this disclosure, and details of exemplary embodiments will be described later with reference to other accompanying drawings.

[0086] Source DU 110 determines (5010) whether the TA value between source cell 101 and terminal device 150-1 of source DU 110 is the same as the TA value between target cell 102 and terminal device 150-1 of target DU 130. In other words, source DU 110 can determine whether source cell 101 and target cell 102 share the same TA value. In some example embodiments, source DU 110 can determine whether source cell 101 and target cell 102 share the same TA value based on historical TA information. For example, whether information about source cell 101 and target cell 102 can be pre-stored at source DU 110, and source DU 110 can make a determination based on the stored information (5010).

[0087] In an example embodiment, source DU 110 can determine a list of cell pairs that share the same timing advance value. In this case, the determined list of cell pairs may include a source cell 101 and a target cell 102. In this case, the list of cell pairs can be determined before the LTM procedure. See later. Figure 6 A detailed description of this example embodiment is provided.

[0088] Alternatively, CU 120 can send an indication to source DU 110 of a potential handover from source cell 101 to target cell 102 for terminal device 150-1. In other words, source DU 110 can receive an indication of a potential handover from CU 120. After receiving the indication of a potential handover, source DU 110 can determine whether source cell 101 and target cell 102 share the same TA value.

[0089] Source DU 110 sends (5020) first information to CU 120, which indicates that source cell 101 and target cell 102 share the same timing advance value. In other words, CU 120 receives first information from source DU 110, which indicates that source cell 101 and target cell 102 share the same timing advance. In this way, unnecessary TA acquisition can be avoided and lower signaling requirements can be achieved.

[0090] In some example embodiments, the first information may be sent in an Information Element (IE). For example, the first information may be sent to CU 120 in an IE within an F1 Application Protocol (F1AP) message. As an example, the first information may be LTM group information, which indicates a group of target cells (including target cell 102) that share the same timing advance as source cell 101.

[0091] CU 120 can send (5030) an instruction to target DU 130 to release the resource acquired by the TA. In other words, target DU 130 can receive (5030) the instruction to release the resource acquired by the TA from CU 120. In some example embodiments, in an intra-CU scenario, CU 120 can directly send the instruction to target DU 130 to release the resource acquired by the TA. Alternatively, in an inter-CU scenario, CU 120 can send the instruction to CU 140 to release the resource acquired by the TA, and CU 140 can then forward the instruction to target DU 130 to release the resource acquired by the TA. Target DU 130 can release (5040) the resource acquired by the TA based on this instruction. In this way, unnecessary resource reservations can be prevented and resource waste can be avoided.

[0092] Source DU 110 can send (5050) a second message indicating a timing advance value as the timing advance value for target cell 102 without triggering timing advance acquisition. In this way, it can reduce UE interruptions and achieve lower signaling.

[0093] Figure 6 A signaling flow 600 providing a timing advance value is illustrated according to an example embodiment of this disclosure. For purposes of discussion, reference will be made, for example, to source DU 110, CU 120, and core network device 610 (e.g., Operation, Administration and Maintenance (OAM)). Figure 1 Let's discuss signaling flow 600. Signaling flow 600 can be implemented in intra-CU scenarios or inter-CU scenarios.

[0094] Source DU 110 can determine (6010) a list of cell pairs that share the same TA value. For example, if source cell 101 and target cell 102 share the same TA value, then source DU 110 can determine a cell pair that includes source cell 101 and target cell 102. Alternatively or additionally, if source cell 101 and target cell 103 also share the same TA value, then source DU 110 can determine another cell pair that includes source cell 101 and target cell 103. In this case, the list of cell pairs can include the cell pair of source cell 101 and target cell 102 as well as the cell pair of source cell 101 and target cell 103.

[0095] Source DU 110 can send (6020) a cell pair list to CU 120. In other words, CU 120 can receive a cell pair list from source DU 110. For example, the cell pair list can be sent via a gNB-DU configuration update procedure. In some example embodiments, CU 120 can then send (6030) a cell pair list that does not require TA acquisition to OAM 610.

[0096] According to the reference Figure 6 In the described example embodiment, the CU does not need to request the target DU to provide early TA acquisition configuration, and the source DU 110 does not need to indicate whether the TAs of the source cell 101 and the target DU cell 102 are the same. Therefore, signaling overhead and unnecessary reservations will be resolved through a single signaling.

[0097] Figure 7A Signaling flow 700 for a handover in a CU scenario without timing advance acquisition, according to an example embodiment of this disclosure, is shown. Reference will be made to this document for discussion purposes. Figure 1 For example, signaling flow 700 can be discussed using source DU 110, target DU 130, CU 120 and terminal device 150-1.

[0098] Terminal device 150-1 may send (7001) an L3 measurement report to source DU 110, including L3 measurements of source cell 101 and neighboring cells (e.g., cells 102 and 103). The L3 measurement report means that the L3 values ​​at terminal device 150-1 are filtered and then reported. Filtering is performed to remove the effects of rapid fading and ignore short-term changes. While L1 measurements can be collected more frequently, L3 measurements can be reported over a longer configuration period. Source DU 110 may forward (7002) the L3 measurement report to CU 120.

[0099] CU 120 can perform (7003) handover (HO) decisions. For example, CU 120 can decide to prepare target DU 130 or target cell 102 for handover of terminal equipment 150-1. CU 120 can also decide to prepare the random access channel (RACH) configuration for the physical downlink control channel (PDCCH) commands obtained by the TA for the prepared cell (i.e., target cell 102).

[0100] CU 120 may send a (7004) UE context establishment request to target DU 130 to prepare for handover. CU 120 may also request target DU 130 to provide TA acquisition configuration. For example, the UE context establishment request may include a TA acquisition configuration request. Target DU 130 may send a (7005) UE context establishment response to CU 120. For example, target DU 130 may provide TA acquisition configuration and handover configuration in the UE context establishment response.

[0101] CU 120 can send a (7006) UE context modification request to source DU 110. For example, CU 120 can notify source DU 110 or cell 101 of handover preparation (i.e., indication of potential handover) and request source DU 110 or cell 101 to provide further configuration required for LTM handover preparation and information about the prepared cell (i.e., cell 102).

[0102] Source DU 110 can determine (7007) whether the TA value of source cell 101 is the same as the TA value of target cell 102. For example, source DU 110 can check whether the TA relationship between cell 101 and cell 102 is known based on previous events observed on the source DU 110 side, that is, whether the TA value of source cell 101 is the same as the TA value of target cell 102.

[0103] If the TA value of source cell 101 is the same as the TA value of target cell 102, then source DU 110 can indicate that the TA value of source cell 101 is the same as the TA value of target cell 102. For example, source DU 110 can send a (7008) UE context modification response to CU 120, which includes an IE indicating that the TA value of source cell 101 is the same as the TA value of target cell 102. For example, source DU 110 can indicate that the TA value of source cell 101 is the same as the TA value of target cell 102 through LTM group information.

[0104] CU 120 can generate (7009) a handover configuration that includes measurement configuration and cell configuration. During the generation of the handover configuration, CU 120 can exclude the TA acquisition configuration from the handover configuration. For example, even though CU 120 has already acquired the TA acquisition configuration for target DU 130 or target cell 102, CU 120 can exclude the TA acquisition configuration from the LTM-prepared RRC reconfiguration (received from target DU 130 during UE context establishment).

[0105] CU 120 can send (7010) a handover configuration without TA acquisition configuration to source DU 110 in an RRC message. Source DU 110 can forward (7013) a handover configuration without TA acquisition configuration to terminal device 150-1 in an RRC message. In this way, it can save signaling overhead.

[0106] CU 120 can send (7011) an indication to target DU 130 to release TA acquisition resources. For example, after receiving (7008) an indication from source DU 110 that "TA acquisition configuration is not required in advance," CU 120 can send (7011) a UE context modification request indicating the release of TA acquisition resources / configuration for target DU 130. Target DU 130 can send (7012) a UE context modification response to CU 120. Target DU 130 can then release TA acquisition resources based on this indication. In this way, unnecessary resource reservations can be prevented and resource waste can be avoided.

[0107] After receiving the switch configuration in the RRC configuration, terminal device 150-1 can send an RRC reconfiguration complete message (7014) to source DU 110. Source DU 110 can forward the RRC reconfiguration complete message (7015) to CU 120.

[0108] Terminal device 150-1 may send (7016) an L1 measurement report including one or more candidate cells to source DU 110. For example, the L1 measurement report may indicate the reference signal received power (RSRP) value.

[0109] Since source DU 110 knows that source cell 101 and target cell 102 share the same TA value, source DU 110 can avoid triggering the TA acquisition of the PDCCH command. Source DU 110 can determine (7017) that terminal device 150-1 needs to switch to target cell 102. Terminal device 150-1 can also send (7018) an L1 measurement report about target cell 102 to source DU 110.

[0110] Source DU 110 can trigger (7019) cell change without TA acquisition. For example, source DU 110 can send (7019) a Media Access Control (MAC) CE to terminal device 150-1 to trigger cell change (i.e., change to target cell 102). The MAC CE may also include the TA value of target cell 102. For example, source DU 110 can provide the TA value of source cell 101 as the TA value of target cell 102 to terminal device 150-1. When performing HO, terminal device 150-1 can perform (7020) RACH-free access to target DU 130 by using the TA value provided in the MAC CE. In this way, it can reduce the latency of accessing the target DU and avoid UE interruption.

[0111] Figure 7B Signaling flow 700' for a handover in an inter-CU scenario without timing advance acquisition, according to an example embodiment of this disclosure, is shown. Reference will be made to this document for discussion purposes. Figure 1 For example, signaling flow 700' can be discussed using source DU 110, target DU 130, CU 120 and terminal device 150-1.

[0112] Terminal device 150-1 can send (7001') an L3 measurement report to source DU 110, including L3 measurements of source cell 101 and neighboring cells (e.g., cells 102 and 103). The L3 measurement report means that the L3 values ​​at terminal device 150-1 are filtered and then reported. Filtering is performed to remove the effects of rapid fading and ignore short-term changes. Although L1 measurements can be collected more frequently, L3 measurements can be reported at longer configuration intervals. Source DU 110 can forward (7002') the L3 measurement report to CU 120.

[0113] CU 120 can perform a (7003') handover (HO) decision. For example, CU 120 can decide to prepare target DU 130 or target cell 102 for handover of terminal equipment 150-1. CU 120 can also decide to prepare a random access channel (RACH) configuration for the physical downlink control channel (PDCCH) command obtained by the TA for the prepared cell (i.e., target cell 102). CU 120 can send a (7003.5) handover request to CU 140, which is the CU that is the target DU 130.

[0114] CU 140 can send a (7004') UE context establishment request to target DU 130 to prepare for handover. CU 140 can also request target DU 130 to provide TA acquisition configuration. For example, the UE context establishment request may include a TA acquisition configuration request. Target DU 130 can send a (7005') UE context establishment response to CU 140. For example, target DU 130 may provide TA acquisition configuration and handover configuration in the UE context establishment response.

[0115] CU 120 can send a (7006') UE context modification request to source DU 110. For example, CU 120 can notify source DU 110 or cell 101 of handover preparation (i.e., indication of potential handover) and request source DU 110 or cell 101 to provide further configuration required for LTM handover preparation and information about the ready cell (i.e., cell 102).

[0116] Source DU 110 can determine (7007') whether the TA value of source cell 101 is the same as the TA value of target cell 102. For example, source DU 110 can check whether the TA relationship between cell 101 and cell 102 is known based on previous events observed on the source DU 110 side, i.e., whether the TA value of source cell 101 is the same as the TA value of target cell 102. CU 140 can send a (7007.5) handover request acknowledgment (ACK) to CU 120.

[0117] If the TA value of source cell 101 is the same as the TA value of target cell 102, then source DU 110 can indicate that the TA value of source cell 101 is the same as the TA value of target cell 102. For example, source DU 110 can send a (7008') UE context modification response to CU 120, which includes an IE indicating that the TA value of source cell 101 is the same as the TA value of target cell 102. For example, source DU 110 can indicate that the TA value of source cell 101 is the same as the TA value of target cell 102 through LTM group information.

[0118] CU 120 can generate (7009') a handover configuration that includes measurement configuration and cell configuration. During the generation of the handover configuration, CU 120 can exclude the TA acquisition configuration from the handover configuration. For example, even though CU 120 has already acquired the TA acquisition configuration for target DU130 or target cell 102, CU 120 can exclude the TA acquisition configuration from the RRC reconfiguration prepared by LTM (received from target DU 130 during UE context establishment).

[0119] CU 120 can send (7010') a handover configuration without TA acquisition configuration to source DU 110 in an RRC message. Source DU 110 can forward (7013') a handover configuration without TA acquisition configuration to terminal device 150-1 in an RRC message. In this way, it can save signaling overhead.

[0120] CU 120 can send a (7010.5) handover update request to CU 140 indicating that TA acquisition is not required. CU 140 can send (7011') an indication to target DU 130 to release TA acquisition resources. For example, after receiving a (7010.5) handover update request from CU 120 indicating "TA acquisition configuration not required," CU 140 can send a (7011') UE context modification request indicating the release of TA acquisition resources / configuration for target DU 130. Target DU 130 can send a (7012') UE context modification response to CU 140. Target DU 130 can release TA acquisition resources based on this indication. In this way, unnecessary resource reservations can be prevented and resource waste can be avoided. CU 140 can send a (7012.5) handover update ACK to CU 120.

[0121] After receiving the handover configuration in the RRC configuration, terminal device 150-1 can send an RRC reconfiguration complete message (7014') to source DU 110. Source DU 110 can then forward the RRC reconfiguration complete message (7015') to CU 120.

[0122] Terminal device 150-1 may send (7016') an L1 measurement report including one or more candidate cells to source DU 110. For example, the L1 measurement report may indicate the reference signal received power (RSRP) value.

[0123] Since source DU 110 knows that source cell 101 and target cell 102 share the same TA value, source DU 110 can avoid triggering the TA acquisition of the PDCCH command. Source DU 110 can determine (7017') that terminal device 150-1 needs to switch to target cell 102. Terminal device 150-1 can also send (7018') an L1 measurement report about target cell 102 to source DU 110.

[0124] Source DU 110 can trigger a cell change (7019') without obtaining a TA. For example, source DU 110 can send a Media Access Control (MAC) CE (7019') to terminal device 150-1 to trigger a cell change (i.e., change to target cell 102). The MAC CE can also include the TA value of target cell 102. For example, source DU 110 can provide the TA value of source cell 101 as the TA value of target cell 102 to terminal device 150-1. When performing an HO, terminal device 150-1 can perform a RACH-free access to target DU 130 by using the TA value provided in the MAC CE (7020'). In this way, it can reduce the latency of accessing the target DU and avoid UE interruption.

[0125] Figure 8A Signaling flow 800 for a handover in a CU-in-containment scenario without timing advance acquisition, according to other exemplary embodiments of this disclosure, is illustrated. Reference will be made to this document for discussion purposes. Figure 1 For example, signaling flow 800 can be discussed using source DU 110, target DU 130, CU120 and terminal device 150-1.

[0126] Terminal device 150-1 may send (8001) an L3 measurement report to source DU 110, including L3 measurements of source cell 101 and neighboring cells (e.g., cells 102 and 103). The L3 measurement report means that the L3 values ​​at terminal device 150-1 are filtered and then reported. Filtering is performed to remove the effects of rapid fading and ignore short-term changes. While L1 measurements can be collected more frequently, L3 measurements can be reported over a longer configuration period. Source DU 110 may forward (8002) the L3 measurement report to CU 120.

[0127] CU 120 can perform (8003) handover (HO) decisions. For example, CU 120 can decide to prepare target DU 130 or target cell 102 for handover of terminal equipment 150-1. CU 120 can also decide to prepare the random access channel (RACH) configuration for the physical downlink control channel (PDCCH) commands obtained by the TA for the prepared cell (i.e., target cell 102).

[0128] CU 120 can send a (8004) UE context modification request to source DU 110. For example, CU 120 can notify source DU 110 or cell 101 of handover preparation (i.e., indication of potential handover) and request source DU 110 or cell 101 to provide further configuration required for LTM handover preparation and information about the ready cell (i.e., cell 102).

[0129] Source DU 110 can determine (8005) whether the TA value of source cell 101 is the same as the TA value of target cell 102. For example, source DU 110 can check whether the TA relationship between cell 101 and cell 102 is known based on previous events observed on the source DU 110 side, that is, whether the TA value of source cell 101 is the same as the TA value of target cell 102.

[0130] If the TA value of source cell 101 is the same as the TA value of target cell 102, then source DU 110 can indicate that the TA value of source cell 101 is the same as the TA value of target cell 102. For example, source DU 110 can send a (8006) UE context modification response to CU 120, which includes an IE indicating that the TA value of source cell 101 is the same as the TA value of target cell 102. For example, source DU 110 can indicate that the TA value of source cell 101 is the same as the TA value of target cell 102 through LTM group information.

[0131] CU 120 can send a (8007) UE Context Establishment Request to target DU 130 to prepare for handover. In this case, CU 120 does not request TA Acquisition Configuration from target DU 130. For example, the UE Context Establishment Request does not include a TA Acquisition Configuration request. Target DU 130 can send a (8008) UE Context Establishment Response to CU 120. Since CU 120 does not request TA Acquisition Configuration, target DU 130 does not provide TA Acquisition Configuration to CU 120. In this way, it can reduce signaling overhead.

[0132] CU 120 can generate (8009) a handover configuration that includes measurement configuration and cell configuration. During the generation of the handover configuration, since CU 120 does not receive TA acquisition configuration from the target DU 130, the handover configuration does not include TA acquisition configuration.

[0133] CU 120 can send (8010) a handover configuration without TA acquisition configuration to source DU 110 in an RRC message. Source DU 110 can forward (8011) a handover configuration without TA acquisition configuration to terminal device 150-1 in an RRC message. In this way, it can save signaling overhead.

[0134] After receiving the switch configuration in the RRC configuration, terminal device 150-1 can send an RRC reconfiguration complete message (8012) to source DU 110. Source DU 110 can forward the RRC reconfiguration complete message (8013) to CU 120.

[0135] Terminal device 150-1 may send (8014) an L1 measurement report including one or more candidate cells to source DU 110. For example, the L1 measurement report may indicate the reference signal received power (RSRP) value.

[0136] Since source DU 110 knows that source cell 101 and target cell 102 share the same TA value, source DU 110 can avoid triggering the TA acquisition of the PDCCH command. Source DU 110 can determine (8015) that terminal device 150-1 needs to switch to target cell 102. Terminal device 150-1 can also send (8016) an L1 measurement report about target cell 102 to source DU 110.

[0137] Source DU 110 can trigger (8017) a cell change without TA acquisition. For example, source DU 110 can send (8017) a Media Access Control (MAC) CE to terminal device 150-1 to trigger a cell change (i.e., a change to target cell 102). The MAC CE can also include the TA value of target cell 102. For example, source DU 110 can provide the TA value of source cell 101 as the TA value of target cell 102 to terminal device 150-1. When performing HO, terminal device 150-1 can perform (8018) RACH-free access to target DU 130 by using the TA value provided in the MAC CE. In this way, it can reduce the latency of accessing the target DU and avoid UE interruption.

[0138] Figure 8B Signaling flow 800' for a handover in an inter-CU scenario without timing advance acquisition, according to other example embodiments of this disclosure, is illustrated. Reference will be made to this document for discussion purposes. Figure 1 For example, signaling flow 800' can be discussed using source DU 110, target DU 130, CU 120, CU 140 and terminal device 150-1.

[0139] Terminal device 150-1 can send (8001') an L3 measurement report to source DU 110, including L3 measurements of source cell 101 and neighboring cells (e.g., cells 102 and 103). The L3 measurement report means that the L3 values ​​at terminal device 150-1 are filtered and then reported. Filtering is performed to remove the effects of rapid fading and ignore short-term changes. Although L1 measurements can be collected more frequently, L3 measurements can be reported at longer configuration intervals. Source DU 110 can forward (8002') the L3 measurement report to CU 120.

[0140] CU 120 can perform (8003') handover (HO) decisions. For example, CU 120 can decide to prepare target DU 130 or target cell 102 for handover of terminal equipment 150-1. CU 120 can also decide to prepare the random access channel (RACH) configuration for the physical downlink control channel (PDCCH) commands obtained by the TA for the prepared cell (i.e., target cell 102).

[0141] CU 120 can send a (8004') UE context modification request to source DU 110. For example, CU 120 can notify source DU 110 or cell 101 of handover preparation (i.e., indication of potential handover) and request source DU 110 or cell 101 to provide further configuration required for LTM handover preparation and information about the ready cell (i.e., cell 102).

[0142] Source DU 110 can determine whether the TA value of source cell 101 is the same as the TA value of target cell 102 (8005'). For example, source DU 110 can check whether the TA relationship between cell 101 and cell 102 is known based on previous events observed on the source DU 110 side, that is, whether the TA value of source cell 101 is the same as the TA value of target cell 102.

[0143] If the TA value of source cell 101 is the same as the TA value of target cell 102, then source DU 110 can indicate that the TA value of source cell 101 is the same as the TA value of target cell 102. For example, source DU 110 can send a (8006') UE context modification response to CU 120, which includes an IE indicating that the TA value of source cell 101 is the same as the TA value of target cell 102. For example, source DU 110 can indicate that the TA value of source cell 101 is the same as the TA value of target cell 102 through LTM group information.

[0144] CU 120 can send a (8006.5) handover request to CU 140 indicating that TA acquisition is not required. CU 140 can send a (8007') UE context establishment request to target DU 130 to prepare for handover. In this case, CU 140 does not request TA acquisition configuration from target DU 130. For example, the UE context establishment request does not include a TA acquisition configuration request. Target DU 130 can send a (8008') UE context establishment response to CU 140. Since CU 140 does not request TA acquisition configuration, target DU 130 does not provide TA acquisition configuration to CU 140. In this way, it can reduce signaling overhead. CU 140 can send a (8009.5) handover request ACK to CU 120.

[0145] The CU 120 can generate (8009') a handover configuration that includes measurement configuration and cell configuration. During the handover configuration generation process, the TA acquisition configuration is not included because the CU 120 does not obtain the TA acquisition configuration.

[0146] CU 120 can send a handover configuration (8010') without TA acquisition configuration to source DU 110 in an RRC message. Source DU 110 can forward the handover configuration (8011') without TA acquisition configuration to terminal device 150-1 in an RRC message. In this way, it can save signaling overhead.

[0147] After receiving the handover configuration in the RRC configuration, terminal device 150-1 can send an RRC reconfiguration complete message (8012') to source DU 110. Source DU 110 can then forward the RRC reconfiguration complete message (8013') to CU 120.

[0148] Terminal device 150-1 may send (8014') an L1 measurement report including one or more candidate cells to source DU 110. For example, the L1 measurement report may indicate the reference signal received power (RSRP) value.

[0149] Since source DU 110 knows that source cell 101 and target cell 102 share the same TA value, source DU 110 can avoid triggering the TA acquisition of the PDCCH command. Source DU 110 can determine (8015') that terminal device 150-1 needs to switch to target cell 102. Terminal device 150-1 can also send (8016') an L1 measurement report about target cell 102 to source DU 110.

[0150] Source DU 110 can trigger a cell change (8017') without obtaining a TA. For example, source DU 110 can send a Media Access Control (MAC) CE (8017') to terminal device 150-1 to trigger a cell change (i.e., change to target cell 102). The MAC CE can also include the TA value of target cell 102. For example, source DU 110 can provide the TA value of source cell 101 as the TA value of target cell 102 to terminal device 150-1. When performing an HO, terminal device 150-1 can perform (8018') RACH-free access to target DU 130 by using the TA value provided in the MAC CE. In this way, it can reduce the latency of accessing the target DU and avoid UE interruption.

[0151] Figure 9 A flowchart of an example method 900 implemented at a source DU according to some example embodiments of the present disclosure is shown. For example, method 900 can be implemented at a source DU. Figure 1 It is implemented at source DU 110.

[0152] At box 910, the source DU determines whether the timing advance value between the source cell and the terminal device of the source distributed unit is the same as the timing advance value between the target cell and the terminal device of the target distributed unit. Potential handovers between the source distributed unit and the target distributed unit and the terminal device are associated.

[0153] At box 920, if the timing advance value is the same as the timing advance value between the target cell and the terminal device, the source DU sends a first message to the central unit of the source distributed unit, which indicates that the source cell and the target cell share the same timing advance value.

[0154] In some example embodiments, the first information is layer 1 / layer 2 triggered mobility group information that indicates a target cell group that shares the same timing advance value as the source cell.

[0155] In some example embodiments, method 900 includes: determining a list of cell pairs sharing the same timing advance value at a source distributed unit, the cell pair list including a source cell and a target cell; and sending first information including the cell pair list to a central unit.

[0156] In some example embodiments, method 900 includes: receiving from a central unit an indication of a potential handover from a source cell to a target cell by a terminal device; and sending first information to the central unit after receiving the indication of the potential handover.

[0157] In some example embodiments, method 900 includes sending second information to a terminal device, the second information indicating a timing advance value as the timing advance value of the target cell, without triggering timing advance acquisition.

[0158] In some example embodiments, the source distributed unit and the target distributed unit share a central unit, or the source distributed unit and the target distributed unit belong to different central units.

[0159] Figure 10 A flowchart illustrating an example method 1000 implemented at a CU device according to some example embodiments of the present disclosure is shown. For example, method 1000 can be implemented at a CU device. Figure 1 Implemented at CU 120.

[0160] At box 1010, the CU receives first information from the source distributed unit of the central unit, indicating that the source cell of the source distributed unit and the target cell of the target distributed unit share the same timing advance value. The timing advance value between the source cell and the terminal device is the same as the timing advance value between the target cell and the terminal device. Potential handover between the source distributed unit and the target distributed unit and the terminal device is associated with these components.

[0161] In some example embodiments, the first information is layer 1 / layer 2 triggered mobility group information that indicates a target cell group that shares the same timing advance value as the source cell.

[0162] In some example embodiments, method 1000 includes: sending a timing advance acquisition configuration request to a target distributed unit or a target central unit of the target distributed unit; receiving a timing advance acquisition configuration from the target distributed unit or the target central unit; after receiving the timing advance acquisition configuration, sending an indication to a source distributed unit, the indication indicating a potential handover of the terminal device from the source cell to the target cell; and receiving first information from the source distributed unit.

[0163] In some example embodiments, method 1000 includes: generating a handover configuration including a measurement configuration and a cell configuration; excluding a timing advance acquisition configuration from the handover configuration; sending a handover configuration without a timing advance acquisition configuration to a source distributed unit; and sending an indication to a target distributed unit or a target central unit for releasing timing acquisition resources at the target distributed unit.

[0164] In some example embodiments, method 1000 includes: sending an indication to a source distributed unit of a potential handover of a terminal device from a source cell to a target cell; receiving first information from the source distributed unit; after receiving the first information, sending a user context establishment request without a timing lead time to a target distributed unit or a target central unit; and receiving a user context establishment response without a timing lead time to the target distributed unit or the target central unit.

[0165] In some example embodiments, method 1000 includes: generating a handover configuration including a measurement configuration and a cell configuration without a timing advance acquisition configuration, and sending the handover configuration without a timing advance acquisition configuration to a source distributed unit.

[0166] In some example embodiments, the first information includes a list of cell pairs that share the same timing advance value, the cell pair list including a source cell and a target cell, and the cell pair list is sent to the core network device.

[0167] In some example embodiments, method 1000 includes: sending an indication to a source distributed unit of a potential handover of a terminal device from a source cell to a target cell; sending a user context establishment request without a timing advance acquisition configuration request to a target distributed unit or a target central unit of the target distributed unit; and receiving a user context establishment response without a timing advance acquisition configuration from the target distributed unit or the target central unit.

[0168] In some example embodiments, the source distributed unit and the target distributed unit share a central unit, or the source distributed unit and the target distributed unit belong to different central units.

[0169] Figure 11 A flowchart illustrating an example method 1100 implemented at a third device according to some example embodiments of the present disclosure is shown. For example, method 1100 can be implemented at a third device. Figure 1 The target DU 130 was achieved.

[0170] At box 1110, the target DU receives an instruction from the central unit of the target distributed unit, which is used to release timed acquisition resources at the target distributed unit. The target distributed unit is associated with a potential handover of the terminal device.

[0171] In box 1120, the target DU releases the timed acquired resources based on this instruction.

[0172] Figure 12 A flowchart illustrating an example method 1200 implemented at a terminal device according to some example embodiments of the present disclosure is shown. For example, method 1200 can be implemented at a terminal device. Figure 1 The system is implemented in 150 terminal devices.

[0173] At box 1210, the terminal device sends a measurement report to the source distributed unit, which includes measurements of the source cell and a set of neighboring cells of the source distributed unit.

[0174] At box 1220, the terminal device receives an indication of the target cell from the target distributed unit from the source distributed unit, the target cell being from the group of neighboring cells. The source distributed unit and the target distributed unit are associated with a potential handover of the terminal device.

[0175] At box 1230, the terminal device receives information from the source distributed unit that indicates the timing advance value as the timing advance value of the target cell, without triggering timing advance acquisition.

[0176] In some example embodiments, the source distributed unit and the target distributed unit share a central unit, or the source distributed unit and the target distributed unit belong to different central units.

[0177] Figure 13 A flowchart illustrating an example method 1300 implemented at a source DU device according to some example embodiments of the present disclosure is shown. For example, method 1300 can be implemented at a source DU device. Figure 1 It is implemented at source DU 110.

[0178] At box 1310, the source DU receives from the central unit of the source distributed unit an indication of a potential handover from the source cell of the source distributed unit to the target cell of the target distributed unit.

[0179] At box 1320, the source DU determines whether the timing advance value between the source cell and the terminal device can be considered the same as the timing advance value between the target cell and the terminal device.

[0180] At box 1330, if the source distributed unit cannot determine that the timing advance value is the same as the timing advance value between the target cell and the terminal device, the source DU triggers the terminal device to obtain the timing advance of the target cell.

[0181] In some embodiments, at block 1340, the source DU can obtain from the central unit the number of timing advance values ​​between the target cell and a set of terminal devices served by the source cell based on the trigger.

[0182] In some example embodiments, method 1300 includes: determining that the timing advance values ​​are the same based on the number of timing advance values ​​obtained for the target cell meeting a predetermined criterion; and determining that the timing advance values ​​are different based on the number of timing advance values ​​obtained for the target cell not meeting a predetermined criterion.

[0183] In some example embodiments, the pre-determining criteria require that at least one of a predetermined number or predetermined ratio of timing advance values ​​for the target cell is the same as at least one of a predetermined number or predetermined ratio of timing advance values ​​between the source cell and the terminal device.

[0184] In some example embodiments, method 1300 includes receiving a message from a central unit indicating predetermined criteria.

[0185] In some example embodiments, the predetermined criteria are default parameters configured at the source distributed unit.

[0186] In some example embodiments, the predetermined criteria are global parameters for all target distributed cells, or the predetermined criteria are parameters for a pair of target distributed cells, or the predetermined criteria are parameters for each target distributed cell, or the predetermined criteria are parameters for each cell pair.

[0187] In some example embodiments, the source distributed unit and the target distributed unit share a central unit, or the source distributed unit and the target distributed unit belong to different central units.

[0188] In some example embodiments, method 1300 includes determining that the source distributed unit can consider the timing advance value to be the same as the timing advance value between the target cell and the terminal device, thereby avoiding triggering the terminal device to obtain the timing advance for the target cell.

[0189] Figure 14 A flowchart illustrating an example method 1400 implemented at a CU device according to some example embodiments of the present disclosure is shown. For example, method 1400 can be implemented at a CU device. Figure 1 Implemented at CU 120.

[0190] At box 1410, CU 120 obtains a predetermined criterion that can be used to determine whether the timing advance value between the terminal device and the first cell is the same as (or can be considered to be the same as) the timing advance value between the terminal and the second cell.

[0191] At box 1420, CU 120 sends a first message indicating predetermined criteria to the source distributed unit.

[0192] At box 1430, CU 120 sends a second message indicating predetermined criteria to the target distributed unit or the central unit of the target distributed unit. The source distributed unit and the target distributed unit are associated with a potential handover of the terminal equipment.

[0193] In some example embodiments, method 1400 includes: obtaining a predetermined criterion for timing advance acquisition from a core network device; or generating a predetermined criterion for timing advance acquisition.

[0194] In some example embodiments, the source distributed unit and the target distributed unit share a central unit, or the source distributed unit and the target distributed unit belong to different central units.

[0195] In some example embodiments, any method 900 can be performed (e.g., Figure 1 The first device (source DU 110) may include a component for performing the corresponding operation of method 900. This component may be implemented in any suitable form. For example, the component may be implemented in a circuit or software module. The first device may be implemented as or included in... Figure 1 In the source DU110.

[0196] In some example embodiments, the first apparatus includes: a component for determining whether a timing advance value between a source cell of a source distributed unit and a terminal device is the same as a timing advance value between a target cell of a target distributed unit and a terminal device, wherein determining the potential handover between the source distributed unit and the target distributed unit and the terminal device is associated; and a component for sending first information to the central unit of the source distributed unit based on the timing advance value being the same as the timing advance value between the target cell and the terminal device, the first information indicating that the source cell and the target cell share the same timing advance value.

[0197] In some example embodiments, the first information is Layer 1 / Layer 2 triggered mobility group information, which indicates a target cell group that shares the same timing advance value as the source cell.

[0198] In some example embodiments, the first apparatus includes: components for determining, at a source distributed unit, a list of cell pairs sharing the same timing advance value, the cell pair list including a source cell and a target cell; and components for sending first information including the cell pair list to a central unit.

[0199] In some example embodiments, the first device includes components for receiving from the central unit an indication of a potential handover of a terminal device from a source cell to a target cell; and components for sending first information to the central unit after receiving the indication of the potential handover.

[0200] In some example embodiments, the first device includes a component for sending second information to a terminal device, the second information indicating a timing advance value as the timing advance value of the target cell without triggering timing advance acquisition.

[0201] In some example embodiments, the source distributed unit and the target distributed unit share a central unit, or the source distributed unit and the target distributed unit belong to different central units.

[0202] In some example embodiments, the first device further includes components for performing other operations in some example embodiments of method 900 or source DU 110. In some example embodiments, 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 first device to perform corresponding operations.

[0203] In some example embodiments, any method 1000 can be executed (e.g., Figure 1 The second device (CU 120) may include a component for performing the corresponding operation of method 1000. This component may be implemented in any suitable form. For example, the component may be implemented in a circuit or software module. The second device may be implemented as or included in... Figure 1 In CU 120.

[0204] In some example embodiments, the second device includes a component for receiving first information from a source distributed unit of the central unit, the first information indicating that the source cell of the source distributed unit and the target cell of the target distributed unit share the same timing advance value, wherein the source distributed unit and the target distributed unit are associated with a potential handover of the terminal device.

[0205] In some example embodiments, the first information is layer 1 / layer 2 triggered mobility group information that indicates a target cell group that shares the same timing advance value as the source cell.

[0206] In some example embodiments, the second apparatus includes: components for sending a timing advance acquisition configuration request to a target distributed unit or a target central unit of the target distributed unit; components for receiving the timing advance acquisition configuration from the target distributed unit or the target central unit; components for sending an indication to a source distributed unit after receiving the timing advance acquisition configuration, the indication indicating a potential handover of the terminal device from the source cell to the target cell; and components for receiving first information from the source distributed unit.

[0207] In some example embodiments, the second apparatus includes: components for generating a handover configuration, the handover configuration including a measurement configuration and a cell configuration; components for excluding a timing advance acquisition configuration from the handover configuration; components for sending a handover configuration without a timing advance acquisition configuration to a source distributed unit; and components for sending an instruction to a target distributed unit or a target central unit for releasing timing acquisition resources at the target distributed unit.

[0208] In some example embodiments, the second apparatus includes: components for sending an indication to a source distributed unit of a potential handover of a terminal device from a source cell to a target cell; components for receiving first information from the source distributed unit; components for sending a user context establishment request without a timing lead acquisition configuration request to a target distributed unit or a target central unit after receiving the first information; and components for receiving a user context establishment response without a timing lead acquisition configuration from the target distributed unit or the target central unit.

[0209] In some example embodiments, the second apparatus includes components for generating a handover configuration that includes a measurement configuration and a cell configuration without timing advance acquisition configuration, and components for sending the handover configuration without timing advance acquisition configuration to the source distributed unit.

[0210] In some example embodiments, the first information includes a list of cell pairs that share the same timing advance value, the cell pair list including a source cell and a target cell, and a component for sending the cell pair list to the core network equipment.

[0211] In some example embodiments, the second apparatus includes: components for sending an indication to a source distributed unit of a potential handover of a terminal device from a source cell to a target cell; components for sending a user context establishment request without a timing advance acquisition configuration request to a target distributed unit or a target central unit of the target distributed unit; and components for receiving a user context establishment response without a timing advance acquisition configuration from the target distributed unit or the target central unit.

[0212] In some example embodiments, the source distributed unit and the target distributed unit share a central unit, or the source distributed unit and the target distributed unit belong to different central units.

[0213] In some example embodiments, the second device further includes components for performing other operations in some example embodiments of method 1000 or CU 120. In some example embodiments, 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 second device to perform corresponding operations.

[0214] In some example embodiments, any method 1100 can be performed (e.g., Figure 1 The third device of the target DU 130 may include a component for performing the corresponding operation of method 1100. This component may be implemented in any suitable form. For example, the component may be implemented in a circuit or software module. The third device may be implemented as or included in Figure 1 The target is DU 130.

[0215] In some example embodiments, the third device includes: a component for receiving an instruction from a central unit of a target distributed unit for releasing a timed acquisition resource at the target distributed unit, wherein the target distributed unit is associated with a potential handover of a terminal device; and a component for releasing the timed acquisition resource based on the instruction.

[0216] In some example embodiments, the third device further includes components for performing other operations in some example embodiments of method 1100 or target DU 130. In some example embodiments, 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 third device to perform corresponding operations.

[0217] In some example embodiments, any method 1200 can be performed (e.g., Figure 1 The fourth means of the terminal device 150 may include components for performing corresponding operations of method 1200. These components may be implemented in any suitable form. For example, the components may be implemented in a circuit or software module. The fourth means may be implemented as or included in... Figure 1 Among the 150 terminal devices.

[0218] In some example embodiments, the fourth device includes: components for sending a measurement report to a source distributed unit, the measurement report including measurements of a source cell of the source distributed unit and a set of neighboring cells; components for receiving an indication from the source distributed unit of a target distributed unit of a target cell from the set of neighboring cells, wherein the source distributed unit and the target distributed unit are associated with a potential handover of a terminal device; and components for receiving information from the source distributed unit indicating a timing advance value as a timing advance value for the target cell without triggering a timing advance acquisition.

[0219] In some example embodiments, the source distributed unit and the target distributed unit share a central unit, or the source distributed unit and the target distributed unit belong to different central units.

[0220] In some example embodiments, the fourth device also includes means for performing other operations in some example embodiments of method 1200 or terminal device 150. In some example embodiments, the component includes: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the fourth device to perform corresponding operations.

[0221] In some example embodiments, any method 1300 can be performed (e.g., Figure 1 The fifth device (source DU 110) may include components for performing the corresponding operations of method 1300. These components may be implemented in any suitable form. For example, the components may be implemented in a circuit or software module. The fifth device may be implemented as or included in... Figure 1 In the source DU110.

[0222] In some example embodiments, the fifth device includes: components for receiving from the central unit of the source distributed unit an indication of a potential handover of a terminal device from a source cell of the source distributed unit to a target cell of the target distributed unit; components for determining whether the timing advance value between the source cell and the terminal device can be considered to be the same as the timing advance value between the target cell and the terminal device; and components for triggering the terminal device to acquire the timing advance value of the target cell based on the determination that the source distributed unit cannot consider the timing advance value to be the same as the timing advance value between the target cell and the terminal device.

[0223] In some example embodiments, the fifth device includes: a component for determining that timing advance values ​​are the same based on the number of timing advance values ​​obtained for the target cell meeting a predetermined criterion; or a component for determining that timing advance values ​​are different based on the number of timing advance values ​​obtained for the target cell not meeting a predetermined criterion.

[0224] In some example embodiments, the pre-determining criteria require that at least one of a predetermined number or predetermined ratio of timing advance values ​​for the target cell is the same as at least one of a predetermined number or predetermined ratio of timing advance values ​​between the source cell and the terminal device.

[0225] In some example embodiments, the fifth device includes a component for receiving a message indicating predetermined criteria from the central unit.

[0226] In some example embodiments, the predetermined criteria are default parameters configured at the source distributed unit.

[0227] In some example embodiments, the predetermined criteria are global parameters for all target distributed cells, or the predetermined criteria are parameters for a pair of target distributed cells, or the predetermined criteria are parameters for each target distributed cell, or the predetermined criteria are parameters for each cell pair.

[0228] In some example embodiments, the fifth device includes: a component for avoiding triggering the terminal device to obtain the timing advance for the target cell based on the determination that the source distributed unit can consider the timing advance value to be the same as the timing advance value between the target cell and the terminal device.

[0229] In some example embodiments, the source distributed unit and the target distributed unit share a central unit, or the source distributed unit and the target distributed unit belong to different central units.

[0230] In some example embodiments, the fifth device further includes components for performing additional operations in some example embodiments of method 1300 or source DU 110. In some example embodiments, 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 fifth device to perform corresponding operations.

[0231] In some example embodiments, any method 1400 can be performed (e.g., Figure 1 The sixth device (CU 120) may include components for performing the corresponding operations of method 1400. These components may be implemented in any suitable form. For example, the components may be implemented in a circuit or software module. The sixth device may be implemented as or included in... Figure 1 In CU 120.

[0232] In some example embodiments, the sixth device includes: components for obtaining a predetermined criterion, which can be used to determine whether a timing advance value between the terminal device and a first cell is the same as a timing advance value between the terminal device and a second cell; components for sending a first message indicating the predetermined criterion to a source distributed unit; and components for sending a second message indicating the predetermined criterion to a target distributed unit or a central unit of the target distributed unit, wherein the source distributed unit and the target distributed unit are associated with a potential handover of the terminal device.

[0233] In some example embodiments, the sixth device includes components for obtaining predetermined criteria for timing advance acquisition from core network equipment; or components for generating predetermined criteria for timing advance acquisition.

[0234] In some example embodiments, the source distributed unit and the target distributed unit share a central unit, or the source distributed unit and the target distributed unit belong to different central units.

[0235] In some example embodiments, the sixth device also includes components for performing other operations in some example embodiments of method 1400 or CU 120. In some example embodiments, 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 sixth device to perform corresponding operations.

[0236] Figure 15 This is a simplified block diagram of a device 1500 suitable for implementing exemplary embodiments of the present disclosure. The device 1500 can be provided to implement a communication device, such as... Figure 1The source DU 110, CU 120, target DU 130, CU 140, and terminal device 150 are shown. As shown, device 1500 includes one or more processors 1510, one or more memories 1520 coupled to processor 1510, and one or more communication modules 1540 coupled to processor 1510.

[0237] Communication module 1540 is used for bidirectional communication. Communication module 1540 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interface can represent any interface required for communication with other network elements. In some example embodiments, communication module 1540 may include at least one antenna.

[0238] As a non-limiting example, processor 1510 can be any type suitable for a local technology network and can include one or more of the following: general-purpose computer, special-purpose computer, microprocessor, digital signal processor (DSP), and processor based on a multi-core processor architecture. Device 1500 can have multiple processors, such as application-specific integrated circuit chips, which are time-dependent on the clock of a synchronous main processor.

[0239] Memory 1520 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 1524, electrically programmable read-only memory (EPROM), flash memory, hard disk, optical disc (CD), digital video disc (DVD), optical disc, laser disc, and other magnetic and / or optical storage. Examples of volatile memories include, but are not limited to, random access memory (RAM) 1522 and other volatile memories that will not persist for the duration of a power outage.

[0240] Computer program 1530 includes computer-executable instructions that are executed by an associated processor 1510. The instructions of program 1530 may include instructions for performing operations / actions of some example embodiments of this disclosure. Program 1530 may be stored in memory (e.g., ROM 1524). Processor 1510 can perform any suitable actions and processes by loading program 1530 into RAM 1522.

[0241] Example embodiments of this disclosure can be implemented by program 1530, enabling device 1500 to execute as described in the reference. Figures 2 to 14 Any process discussed in this disclosure. Exemplary embodiments of this disclosure may also be implemented by hardware or by a combination of software and hardware.

[0242] In some example embodiments, program 1530 may be tangibly contained in a computer-readable medium, which may be included in device 1500 (such as memory 1520) or other storage device accessible by device 1500. Device 1500 may load program 1530 from the computer-readable medium into RAM 1522 for execution. In some example embodiments, the computer-readable medium may include any type of non-transitory storage medium, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. As used herein, the term "non-transitory" is a limitation on the medium itself (i.e., tangible, not tactile) rather than a limitation on the persistence of data storage (e.g., RAM and ROM).

[0243] Figure 16 An example of a computer-readable medium 1600 is shown, which may be in the form of a CD, DVD, or other optical storage disc. A program 1530 is stored on the computer-readable medium 1600.

[0244] Generally, the various embodiments of this disclosure can be implemented in hardware or dedicated circuitry, software, logic, or any combination thereof. Some aspects can be implemented in hardware, while others can be implemented in firmware or software that can be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of this disclosure are illustrated and described as block diagrams, flowcharts, or using some other graphical representation, it should be understood that, as non-limiting examples, the blocks, apparatuses, systems, techniques, or methods described herein can be implemented in hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof.

[0245] Some exemplary embodiments of this disclosure also provide at least one computer program product tangibly stored on a computer-readable medium, such as a non-transitory computer-readable medium. The computer program product includes computer-executable instructions that execute in a device on a target physical or virtual processor, such as those included in a program module, to perform any of the methods described above. Typically, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc., that perform a particular task or implement a particular abstract data type. In various embodiments, the functionality of a program module can be combined or split among program modules as needed. The machine-executable instructions for a program module can execute within a local or distributed device. In a distributed device, the program module can reside in both local and remote storage media.

[0246] Program code used to perform the methods of this disclosure may be written in any combination of one or more programming languages. The program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a machine, partially on a machine, as a stand-alone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0247] In the context of this disclosure, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, etc.

[0248] Computer-readable media can be computer-readable signal media or computer-readable storage media. Computer-readable media can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any suitable combination thereof. More specific examples of computer-readable storage media will include electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable optical disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0249] Furthermore, although operations are described in a specific order, this should not be construed as requiring that such operations be performed in the specific order shown or sequentially, or that all shown operations be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the discussion above, these details should not be construed as limiting the scope of this disclosure, but rather as descriptions of features that may be specific to particular embodiments. Unless explicitly stated otherwise, certain features described in the context of a single embodiment may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated otherwise, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0250] Although this disclosure has been described in language specific to structural features and / or methodological actions, it should be understood that the disclosure as defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are disclosed as exemplary forms for implementing the claims.

Claims

1. A source distributed unit, comprising: At least one processor; as well as At least one memory, the at least one memory storing instructions that, when executed by the at least one processor, cause the source distributed unit to: Determine whether the timing advance value between the source cell and the terminal device of the source distributed unit is the same as the timing advance value between the target cell and the terminal device of the target distributed unit, wherein the potential handover between the source distributed unit and the target distributed unit and the terminal device is associated; as well as Based on the determination that the timing advance value is the same as the timing advance value between the target cell and the terminal device, a first message is sent to the central unit of the source distributed unit, the first message indicating that the source cell and the target cell share the same timing advance value.

2. The source distributed unit according to claim 1, wherein the first information is layer 1 / layer 2 triggered mobility group information, the mobility group information indicating a target cell group that shares the same timing advance value with the source cell.

3. The source distributed unit according to claim 1, wherein the source distributed unit is configured such that: At the source distributed unit, a list of cell pairs sharing the same timing advance value is determined, the cell pair list including a source cell and a target cell; and The first information, including the cell pair list, is sent to the central unit.

4. The source distributed unit according to any one of claims 1 to 3, wherein the source distributed unit is such that: Receive from the central unit an indication of a potential handover from the source cell to the target cell by the terminal device; and After receiving the indication of the potential switch, the first information is sent to the central unit.

5. The source distributed unit according to any one of claims 1 to 4, wherein the source distributed unit is such that: Send a second message to the terminal device, the second message indicating that the timing advance value is used as the timing advance value of the target cell, without triggering timing advance acquisition.

6. A central unit, comprising: At least one processor; as well as At least one memory, the at least one memory storing instructions, the instructions, when executed by the at least one processor, cause the central unit to: The central unit receives first information from its source distributed unit, the first information indicating that the source cell of the source distributed unit and the target cell of the target distributed unit share the same timing advance value, wherein the source distributed unit and the target distributed unit are associated with a potential handover of the terminal device.

7. The central unit according to claim 6, wherein the first information is layer 1 / layer 2 triggered mobility group information, the mobility group information indicating a target cell group that shares the same timing advance value with the source cell.

8. The central unit according to any one of claims 6 to 7, wherein the central unit is configured such that: Send a timing advance acquisition configuration request to the target distributed unit or the target central unit of the target distributed unit; Receive timing advance from the target distributed unit or the target central unit to obtain configuration; After receiving the timing advance acquisition configuration, an indication is sent to the source distributed unit, indicating a potential handover of the terminal device from the source cell to the target cell; and The first information is received from the source distributed unit.

9. The central unit according to claim 8, wherein the central unit is configured such that: Generate a handover configuration, which includes a measurement configuration and a cell configuration; Exclude the timing advance acquisition configuration from the switching configuration; Send the switching configuration without the timing advance acquisition configuration to the source distributed unit; and An instruction is sent to the target distributed unit or the target central unit, the instruction being used to release the timed acquisition resources at the target distributed unit.

10. The central unit according to any one of claims 6 to 7, wherein the central unit is configured such that: Send an indication to the source distributed unit of a potential handover of the terminal device from the source cell to the target cell; Receive the first information from the source distributed unit; After receiving the first information, a user context establishment request without a timing lead time for configuration acquisition is sent to the target distributed unit or the target central unit; and Receive a user context establishment response from the target distributed unit or the target central unit without timing advance for configuration acquisition.

11. The central unit of claim 10, wherein the central unit is configured such that: Generate a handover configuration, which includes a measurement configuration and a cell configuration that does not have the timing advance acquisition configuration, and Send the switching configuration without the timing advance acquisition configuration to the source distributed unit.

12. The central unit according to any one of claims 6 to 11, wherein the first information includes a list of cell pairs sharing the same timing advance value, the cell pair list including a pair of the source cell and the target cell, and The central unit is configured such that: Send the cell pair list to the core network equipment.

13. The central unit according to claim 12, wherein the central unit is configured such that: Send an indication to the source distributed unit of a potential handover of the terminal device from the source cell to the target cell; Send a user context establishment request without timing advance to the target distributed unit or the target central unit of the target distributed unit; and Receive a user context establishment response from the target distributed unit or the target central unit without timing advance for configuration acquisition.

14. A target distributed unit, comprising: At least one processor; as well as At least one memory, the at least one memory storing instructions, which, when executed by the at least one processor, cause the target distributed unit to: Receive an instruction from the central unit of the target distributed unit, the instruction being used to release timed acquisition resources at the target distributed unit, wherein the target distributed unit is associated with a potential handover of a terminal device; and Release the timed acquired resources based on the instruction.

15. A source distributed unit, comprising: At least one processor; as well as At least one memory, the at least one memory storing instructions that, when executed by the at least one processor, cause the source distributed unit to: The terminal device receives an indication of a potential handover from the source cell of the source distributed unit to the target cell of the target distributed unit from the central unit of the source distributed unit; Determine whether the timing advance value between the source cell and the terminal device can be considered the same as the timing advance value between the target cell and the terminal device; and Based on the determination that the source distributed unit cannot consider the timing advance value to be the same as the timing advance value between the target cell and the terminal device, the terminal device is triggered to obtain the timing advance for the target cell.

16. The source distributed unit of claim 15, wherein the source distributed unit is configured such that: The timing advance values ​​are determined to be the same based on the number of timing advance values ​​obtained for the target cell satisfying a predetermined criterion; or The timing advance values ​​are determined to be different based on the fact that the number of timing advance values ​​obtained for the target cell does not meet the predetermined criteria.

17. The source distributed unit of claim 15, wherein the predetermined criterion requires that at least one of a predetermined number or a predetermined ratio of timing advance values ​​for the target cell is the same as at least one of the predetermined number or a predetermined ratio of timing advance values ​​between the source cell and the terminal device.

18. The source distributed unit according to any one of claims 16 to 17, wherein the source distributed unit is such that: Receive a message from the central unit instructing the predetermined criteria.

19. The source distributed unit according to any one of claims 16 to 17, wherein the predetermined criterion is a default parameter configured at the source distributed unit.

20. The source distributed unit according to any one of claims 15 to 19, wherein the source distributed unit is such that: Based on the determination that the source distributed unit can consider the timing advance value to be the same as the timing advance value between the target cell and the terminal device, the terminal device is prevented from obtaining the timing advance value for the target cell.

21. The source distributed unit according to any one of claims 15 to 20, wherein the source distributed unit and the target distributed unit share the central unit, or The source distributed unit and the target distributed unit belong to different central units.

22. A central unit, comprising: At least one processor; as well as At least one memory, the at least one memory storing instructions, the instructions, when executed by the at least one processor, cause the central unit to: A predetermined criterion is obtained, which can be used to determine whether the timing advance value between the terminal device and the first cell is the same as the timing advance value between the terminal device and the second cell; Send a first message indicating the predetermined criteria to the source distributed unit; as well as A second message instructing the predetermined criteria is sent to the target distributed unit or the central unit of the target distributed unit, wherein the source distributed unit and the target distributed unit are associated with a potential handover of the terminal device.

23. The central unit according to claim 22, wherein the central unit is configured such that: Obtain the predetermined criteria for timing advance acquisition from the core network equipment; or Generate the predetermined criteria for obtaining the timing advance.

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