Handling TAT expiration for multiple tags

Abstract

Embodiments of this disclosure provide a solution for handling the expiration of at least one timing alignment timer (TAT) among multiple timing advance groups (TAGs) associated with a serving cell. As an example, a terminal device determines at least two TAGs for a serving cell, at least two of which include a primary TAG and a secondary TAG. The terminal device determines whether at least one of the at least two TAGs has expired, and based on the determination that at least one TAT has expired, maintains one of the primary and secondary TAGs. This eliminates ambiguity in RA procedure / UL signal transmission, as only a single TAG is maintained when the terminal device is in a single TAT / no TAT state. Because the network is aware of the TAT expiration, it can understand the terminal device's operation and respond accordingly.

Description

Technical Field

[0005] ,

[0001] Embodiments of the present disclosure generally relate to the field of communications, and more particularly, to a terminal device, a network device, a method, an apparatus, and a computer-readable medium for handling the expiration of at least one time alignment timer (TAT) of a plurality of timing advance groups (TAGs) associated with a serving cell.

Background Art

[0002] In a New Radio (NR) system, the concept and function of NR timing advance (TA) are substantially the same as those of Long Term Evolution (LTE) timing advance. Briefly speaking, TA is a special instruction (such as a notification) from a network device to a terminal device, whereby the terminal device can adjust uplink transmission. This type of uplink adjustment is applied to the Physical Uplink Shared Channel (PUSCH), Physical Uplink Control Channel (PUCCH), Sounding Reference Signal (SRS), etc.

[0003] In 3GPP (registered trademark) Release 18, it was agreed to support two TA extensions for uplink (UL) multi-downlink control information (DCI) in multiple transceiver point (TRP) operations. However, further consideration is needed for solutions regarding multiple TAs.

Summary of the Invention

[0004] Generally, embodiments of the present disclosure provide a solution for handling a plurality of timing advance values for a user equipment (UE) within a serving cell.

[0005] In a first embodiment, a terminal device is provided. The terminal device comprises at least one processor and at least one memory which stores instructions that, when executed by the at least one processor, cause the terminal device to determine at least two timing advance groups (TAGs) for a serving cell, the at least two TAGs including a primary TAG and a secondary TAG, determine whether at least one time alignment timer (TAT) of the at least two TAGs has expired, and maintain one of the primary TAG and the secondary TAG based on the determination that at least one TAT has expired.

[0006] In a second embodiment, a network device is provided. The network device comprises at least one processor and at least one memory that stores instructions causing the network device to perform, when executed by at least one processor, the following actions: determine at least two timing advance groups (TAGs) for a serving cell, the at least two TAGs including a primary TAG and a secondary TAG; determine whether at least one time alignment timer (TAT) of the at least two TAGs has expired; and determine one of the primary TAG and secondary TAG to be maintained in the terminal device based on the determination that at least one TAT has expired.

[0007] In a third embodiment, a method is provided. The method includes determining, in a terminal device, at least two timing advance groups (TAGs) for a serving cell, the at least two TAGs including a primary TAG and a secondary TAG; determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired; and maintaining one of the primary TAG and the secondary TAG based on the determination that at least one TAT has expired.

[0008] In a fourth embodiment, a method is provided. This method includes determining, in a network device, at least two timing advance groups (TAGs) for a serving cell, the at least two TAGs including a primary TAG and a secondary TAG; determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired; and determining, based on the determination that at least one TAT has expired, one of the primary TAG and secondary TAG to be maintained in the terminal device.

[0009] In a fifth embodiment, an apparatus is provided. The apparatus is a terminal device comprising means for determining at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG; means for determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired; and means for maintaining one of the primary TAG and the secondary TAG based on the determination that at least two TATs have expired.

[0010] In a sixth embodiment, an apparatus is provided. The apparatus is a network device and includes means for determining at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG; means for determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired; and means for determining one of the primary TAG and secondary TAG to be maintained in a terminal device based on the determination that at least one TAT has expired.

[0011] In a seventh embodiment, a non-temporary computer-readable storage medium containing program instructions is provided. When executed by the device, the program instructions cause the device to determine at least two timing advance groups (TAGs) for a serving cell, the at least two TAGs including a primary TAG and a secondary TAG; determine whether at least one time alignment timer (TAT) of the at least two TAGs has expired; and maintain one of the primary TAG and the secondary TAG based on the determination that at least one TAT has expired.

[0012] In an eighth embodiment, a non-temporary computer-readable storage medium containing program instructions is provided. When executed by a device, the program instructions cause the device to determine at least two timing advance groups (TAGs) for a serving cell, the at least two TAGs including a primary TAG and a secondary TAG; determine whether at least one time alignment timer (TAT) of the at least two TAGs has expired; and determine one of the primary TAG and secondary TAG to be maintained in the terminal device based on the determination that at least one TAT has expired.

[0013] In a ninth embodiment, a computer program is provided which, when executed by the device, causes the device to determine at least two timing advance groups (TAGs) for a serving cell, the at least two TAGs including a primary TAG and a secondary TAG; determine whether at least one time alignment timer (TAT) of the at least two TAGs has expired; and maintain one of the primary TAG and the secondary TAG based on the determination that at least one TAT has expired.

[0014] In a tenth embodiment, a computer program is provided which, when executed by the device, causes the device to determine at least two timing advance groups (TAGs) for a serving cell, the at least two TAGs including a primary TAG and a secondary TAG; determine whether at least one time alignment timer (TAT) of the at least two TAGs has expired; and, based on the determination that at least one TAT has expired, determine which of the primary and secondary TAGs should be maintained in the terminal device.

[0015] In an eleventh embodiment, a terminal device is provided. The terminal device comprises: a first circuit configured to determine at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG; a second circuit configured to determine whether at least one time alignment timer (TAT) of the at least two TAGs has expired; and a third circuit configured to maintain one of the primary TAG and the secondary TAG based on the determination that at least one TAT has expired.

[0016] In a twelfth embodiment, a network device is provided. The network device comprises: a first circuit configured to determine at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG; a second circuit configured to determine whether at least one time alignment timer (TAT) of the at least two TAGs has expired; and a third circuit configured to determine, based on the determination that at least one TAT has expired, one of the primary TAG and the secondary TAG to be maintained in the terminal device.

[0017] This summary does not identify any important 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 be readily apparent from the following description. [Brief explanation of the drawing]

[0018] Several embodiments will be described with reference to the attached drawings. [Figure 1] Figure 1 shows an example of a communication network in which an embodiment of the present disclosure may be implemented. [Figure 2] Figure 2 shows an example of a process flow according to some embodiments of this disclosure. [Figure 3] Figure 3 is a flowchart showing an example of a method implemented in a terminal device according to an example of an embodiment of the present disclosure. [Figure 4] Figure 4 is another flowchart illustrating an example of how a method may be implemented in a network device according to an example of an embodiment of the present disclosure. [Figure 5] Figure 5 shows a simplified block diagram of an apparatus suitable for carrying out some embodiments of the present disclosure. [Figure 6] Figure 6 is a block diagram showing an example of a computer-readable medium according to some embodiments of the present disclosure. Throughout the drawings, the same or similar reference numerals indicate the same or similar components.

Best Mode for Carrying Out the Invention

[0019] The principles of the present disclosure will be described with reference to several examples. It should be understood that these examples are not intended to limit the scope of the present disclosure, but are for illustrative purposes only and are described to assist those skilled in the art in understanding and implementing the present disclosure. The present disclosure can be implemented in various ways other than those described in the examples below.

[0020] 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 specification belongs.

[0021] The descriptions such as "one embodiment", "embodiment", "exemplary embodiment" in this specification indicate that the described embodiments may include specific functions, structures, or features, but not all embodiments need to include the specific functions, structures, or features. Further, these expressions do not necessarily refer to the same embodiment. Also, when a specific function, structure, or characteristic is described in relation to an embodiment, it is considered within the knowledge of those skilled in the art to affect the function, structure, or characteristic in relation to other embodiments, whether explicitly described or not.

[0022] Note that terms such as "first" and "second" may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish elements. For example, it is possible to refer to the first element as the second element, and similarly, to refer to the second element as the first element, without departing from the scope of the examples. In this specification, the term "and / or" encompasses any combination including one or more of the recited terms.

[0023] The terms used in this specification are for the sole purpose of describing particular embodiments and are not intended to limit the exemplary embodiments. In this specification, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. Further, the terms "comprise", "comprising", "include", "including", and / or "having" as used in this specification specify the presence of the described features, elements, and / or components, etc., but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. In this specification, in the expressions "at least one of the following: <list of two or more elements>" and "at least one of the following: <list of two or more elements>" and similar expressions, when the list of two or more elements is connected by "and" or "or", it means at least one element, at least two or more elements, or at least all elements.

[0024] In this application, the term "circuit" refers to (a) only hardware circuit implementations (such as implementations using only analog circuits and / or digital circuits), (b) combinations of hardware circuits and software, for example (where applicable), (i) combinations of analog and / or digital hardware circuits and software / firmware, and, (ii) combinations of a part of a hardware processor and software (including a digital signal processor), software, and memory that cooperate to perform various functions in a device such as a mobile phone or a server, (c) hardware circuits and / or processors (such as a microprocessor or a part of a microprocessor) that require software (such as firmware) for operation, but may not have software when it is not required for operation, and may refer to one or more, or all, of the above.

[0025] This definition of "circuit" applies to all uses of this term in this application, i.e., all uses in all claims. For example, as used in this application, the term "circuit" includes not only a mere hardware circuit or processor (or multiple processors), but also a part of a hardware circuit or processor and its associated software and / or firmware implementation. The term "circuit" also includes, for example, a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device, as applicable to the elements of a particular claim.

[0026] In this specification, the terms “Network,” “Communication Network,” or “Data Network” refer to any network conforming to any appropriate communication standard, including Long-Term Evolution (LTE), LTE-Advanced (LTE-A), Broadband Code Division Multiple Access (WCDMA®), High-Speed ​​Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), and Wireless Fidelity (Wi-Fi®). Furthermore, communication between terminal devices and network devices / elements within a communication network may be performed in accordance with any appropriate generation of communication protocol, including but not limited to fourth-generation (4G), 4.5G, future fifth-generation (5G), IEEE 802.11 communication protocol, and / or other protocols currently known or to be developed in the future. Embodiments of this disclosure are applicable to a variety of communication systems. Given the rapid development of communication technology, there will naturally be future communication technologies and systems to which this disclosure will be embodied. The scope of this disclosure should not be construed as being limited only to the aforementioned systems.

[0027] In this specification, the term “network device” refers to a node in a communication network, which serves as a medium for terminal devices to access the network and receive services from it. Network devices may include, for example, base stations (BS), access points (AP), transceiver points (TRP), node B (NodeB or NB), evolved node B (eNodeB or eNB), NR node B (also called gNB), remote radio units (RRU), radio headers (RH), remote radio heads (RRH), WiFi® devices, relays, and low-power nodes such as femto and pico, depending on the terminology and technology applied. In the following description, the terms “network device,” “AP device,” “AP,” and “access point” may be used interchangeably.

[0028] "Terminal equipment" refers to any terminal device capable of wireless communication. While these are merely examples, terminal equipment may also be called communication equipment, user equipment (UE), subscriber station (SS), mobile subscriber station, mobile station (MS), station (STA) or station equipment, or access terminal (AT). Terminal devices include mobile phones, mobile phone terminals, smartphones, VoIP phones, wireless local loop phones, tablet terminals, wearable devices, PDAs, portable computers, desktop computers, image capture devices such as digital cameras, game terminals, music storage and playback devices, in-vehicle wireless terminals, wireless endpoints, mobile stations, laptop-based equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer premises equipment (CPE), Internet of Things (IoT) devices, watches and other wearables, 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 industrial and / or automated processing chain environments), consumer electronics, and devices operating on commercial and / or industrial wireless networks. In the following description, the terms “station,” “station equipment,” “STA,” “terminal equipment,” “communication device,” “terminal,” “user equipment,” and “UE” may be used interchangeably.

[0029] In this specification, the term "TRP" refers to a transmit / receive point (TRP) located at a specific geographical location on the network side, equipped with an antenna array (having one or more antenna elements), used to transmit and receive signals to and from terminal devices. In embodiments of this specification, a TRP may refer to a macrocell, microcell, RRH, relay, femtonode, piconode, etc. Some embodiments of this specification are described with reference to, for example, two TRPs, but these embodiments are not intended to limit the scope of this specification and are merely for illustrative purposes to help those skilled in the art understand and implement this specification. It should be understood that the disclosures described herein can be implemented in various ways other than those described below.

[0030] As mentioned above, a TA is a special command (e.g., a notification) from a network device to a terminal device, which allows the terminal device to coordinate uplink transmissions.

[0031] TAs are delivered to terminal devices via Random Access Responses (RARs) or MAC CEs (Media Access Control Elements). TA loops can be used at network nodes to maintain TAs in order to align UL signals (transmitted from terminal devices) with a specific time resolution. In random access procedures, terminal devices receive an initial TA value (such as an absolute TA value) in a RAR message. Subsequently, the TA value can be updated with a MAC CE containing a Timing Advance Command (TAC) indicating a relative TA value. In addition, UEs can autonomously update TAs by voluntarily requesting updated TA values. These operations to maintain TAs are called TA loops. Typically, a TA loop corresponds to a UL transmission for a specific TRP. A TA loop may also correspond to a TA maintained within a TAG. Therefore, one TA loop corresponds to one TA, and the number of TA loops indicates the number of TAs in use. Thus, in this specification, a TA loop may implicitly refer to a TA.

[0032] A Timing Advance Group (TAG) as used herein refers to a group consisting of one or more serving cells having the same uplink TA and the same downlink timing reference cell. Each TAG includes at least one serving cell with a configured uplink, and the mapping of each serving cell to the TAG is configured by a Radio Resource Control (RRC) signal. 3GPP® Release 18 already agrees to support two TAs for UL multi-DCI for multi-TRP operation in NR systems. Furthermore, 3GPP® Release 18 agrees to extended support for two TAs in both intra-cell and inter-cell multi-DCI multi-TRP scenarios. Multiple (two or more) timing advance values ​​for UEs within a serving cell are under consideration as further Novel (NR) extensions.

[0033] In a multi-TRP scenario, a UE may have two TAGs for a serving cell (such as a SpCell), and these TAGs will naturally employ different Time Alignment Timers (TATs) so that the network (NW) can provide separate timing adjustment commands using TAC MAC CE, etc. Therefore, the (re)start timing of the TATs may differ between these two TAGs.

[0034] In RRC_CONNECTED mode, the UE sets two TA loops / TAGs for a serving cell, more specifically for a SpCell (PCell / PSCell), but the TATs associated with these TAGs may expire at different times. Of the TAGs associated with a SpCell, one may be considered the primary TAG and the other the secondary TAG. The UE's behavior when either or both of these timers expire is unclear.

[0035] Embodiments of this disclosure provide a solution for handling multiple tags upon the expiration of a TAT associated with a serving cell. A UE may have at least two tags for a serving cell, including a primary tag and a secondary tag. When at least one of the TATs for a serving cell (e.g., a SpCell) expires, the UE retains only the primary tag. The tag that becomes the primary tag for a cell group / SpCell can be pre-configured, or if only one tag in the SpCell's tag group has an expiring TAT, the tag whose TAT is still running may become the primary tag. In this way, when the UE is in a state of having a single TAT / not running a TAT, only a single tag is retained, eliminating ambiguity in RA procedure / UL signaling. Because the NW is aware of the TAT expiration, it can understand the UE's behavior and respond accordingly.

[0036] For illustrative purposes, the principles and embodiments of this disclosure will be described below with reference to Figures 1 to 6. However, it should be noted that these embodiments are intended to enable those skilled in the art to understand the inventive concept of this disclosure and to implement the solutions proposed herein, and are not intended to limit the scope of this application in any way.

[0037] Figure 1 shows an example of a communication network 100 in which several embodiments of the present disclosure may be implemented. As shown in Figure 1, the communication network 100 includes terminal equipment (also called user equipment or UE) 110 and two network devices (also called gNB or BS) TRP120-1 and 120-2 (collectively referred to as "120"). Although Figure 1 shows one terminal device 110 and two network devices 120, the number of network devices and terminal devices is not limited. That is, there may be one or more network devices 110 and one or more terminal devices 120 in the network.

[0038] The network device 120 can provide services to the terminal device 110, and the network device 120 and the terminal device 110 can communicate data and control information with each other. In some embodiments, the network device 120 and the terminal device 110 can communicate via a direct link / channel.

[0039] In the communication system 100, the link from the network device 120 to the terminal device 110 is called a downlink (DL), and the link from the terminal device 110 to the network device 120 is called an uplink (UL). In the downlink, the network device 120 is the transmitting (TX) device (or transmitter), and the terminal device 110 is the receiving (RX) device (or receiver). In the uplink, the terminal device 110 is the transmitting device (TX), and the network device 120 is the receiving device (RX). It should be understood that the network device 120 may provide one or more serving cells. As shown in Figure 1, the network device 120 jointly provides a serving cell 102, and the terminal device 110 connects to (camps) the serving cell 102. In some embodiments, the network device 120 may provide multiple serving cells, and the terminal device 120 may switch between serving cells from source to target during its movement. It should be understood that the number of serving cells shown in Figure 1 is illustrative for illustrative purposes only and does not imply any limitation.

[0040] Communication in the network environment 100 may be carried out in accordance with an appropriate communication protocol, which includes, but is not limited to, fourth-generation (4G) and fifth-generation (5G) cellular communication protocols, wireless local network communication protocols such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11, and / or other protocols currently known or to be developed in the future. Furthermore, communication may optionally utilize an appropriate wireless communication technology, which includes, but is not limited to, code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplexing (FDD), time division duplexing (TDD), multiple input multiple output (MIMO), orthogonal frequency division multiplexing (OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM), and other technologies currently known or to be developed in the future.

[0041] In some embodiments, the serving cell 102 may include a primary cell, a primary-secondary cell, or a secondary cell having multiple network devices 120 such as a TRP. As previously mentioned, the terminal device 110 has two TAGs for the serving cell 102, and different TATs can be employed for one of the network devices so that a separate TAC can be provided for each TAG. The terminal device 110 determines that one TAG is the primary TAG and the other is the secondary TAG. When one or more TATs expire, the terminal device 110 retains the primary TAG and one of the secondary TAGs. The network device 120 that provides the TAC is also aware of the TAT expiration. It is aware of the TAG held by the terminal device 110 and can act accordingly.

[0042] The number, connections, and types of devices shown in Figure 1 are illustrative and not intended to be limiting. The communication system 100 may include any number of devices suitable for carrying out the embodiments described herein.

[0043] Figure 2 shows an example of a process flow according to some embodiments of this disclosure. For ease of understanding, process flow 200 will be described with reference to Figure 1. Although process flow 200 is described with reference to the communication network 100 in Figure 1, it should be understood that this process flow 200 is equally applicable to other similar communication scenarios.

[0044] In block 212, the terminal device 110 determines at least two timing advance groups (TAGs) for the serving cell. In some embodiments, the serving cell may include a primary cell, a primary secondary cell, or a secondary cell. In some embodiments, the serving cell may be a special cell (SpCell, i.e., one of PCell or PSCell). The serving cell can provide services using a plurality of network devices 120 (such as a TRP). One of the network devices 120 (hereinafter, network device 120) may be configured to provide control signals to the terminal device 110.

[0045] At least two tags include a primary tag and a secondary tag. The primary tag of a cell group / SpCell is determined by whether it is pre-configured, or if only one TAT has expired among the SpCell's tags, the tag whose TAT is still active becomes the primary tag.

[0046] In some embodiments, the terminal device determines one of at least two tags as the primary tag based on a setting indicating the primary tag. The terminal device 110 can receive RRC connection reconfiguration signals or other control signals from the network device 120 indicating the primary tag. For example, a tag with a lower tag ID may be identified as the primary tag. In some examples, the primary tag is always associated with a SpCell (i.e., a PCell or PSCell).

[0047] If the configured primary TAG becomes invalid, the roles of the primary and secondary TAGs may be swapped. In some embodiments, if the corresponding TAT has expired, the terminal device 110 determines the configured primary TAG to be secondary, and if the TAT is still running, it determines the configured secondary TAG to be primary.

[0048] In block 214, the terminal device 110 determines whether at least one time alignment timer (TAT) of at least two TAGs has expired. TAT expiration means that the terminal device 110 is not synchronized with the network device 120, and the TA value of the corresponding TAG becomes invalid. In some embodiments, the terminal device 110 and the network device 120 must perform a random access (RACH) procedure for synchronization, in which case a new TAC is sent from the network device 120 to the terminal device 110. However, the network device may not explicitly indicate the TAG ID of the new TAC.

[0049] In block 216, terminal device 110 maintains one of the primary and secondary TAGs based on the determination that at least one TAT has expired. By maintaining one of the TAGs, network device 120 and terminal device 110 can eliminate ambiguity in RACH procedure and UL signal transmission.

[0050] In some embodiments, the terminal device 110 may release the secondary TAG settings associated with the secondary TAG. The terminal device releases the secondary TAG settings when both TATs associated with the SpCell's TAG expire, when the TAT associated with the primary TAG expires, or when the TAT associated with one of the TAGs associated with the SpCell expires, after which the other TAG whose TAT is still running becomes the primary TAG. In some examples, the terminal device 110 may release secondary TAG settings only from the SpCell (i.e., PCell or PSCell), or only a portion of the secondary TAG settings associated with the SpCell. In some examples, if the secondary TAG includes serving cells other than the SpCell (e.g., one or more secondary cells), the terminal device 110 retains the secondary TAG settings for the serving cells other than the SpCell.

[0051] In some embodiments, the terminal device 110 releases the secondary TAG settings when the TAT associated with at least two TAGs expires. Additionally or alternatively, the terminal device 110 may release the secondary TAG settings when the TAT associated with the primary TAG expires. Additionally or alternatively, the terminal device 110 may release the secondary TAG settings when the TAT associated with the primary TAG expires, or when the TAT associated with the secondary TAG expires.

[0052] In some embodiments, the terminal device 110 releases the PUCCH resources associated with the secondary TAG. Additionally or alternatively, the terminal device 110 releases the Sounding Reference Signal (SRS) resources associated with the secondary TAG. Additionally or alternatively, the terminal device 110 clears the configured downlink assignments and configured uplink grants associated with the secondary TAG. Additionally or alternatively, the terminal device 110 may clear the PUCCH resources for semi-persistent channel status information (CSI) reporting associated with the secondary TAG.

[0053] In some embodiments, the terminal device 110 may deactivate each of the spatial relationships of any UL signals associated with a TAG (e.g., PUCCH, SRS, PUSCH, etc.) when a TAT expires or when a secondary TAG setting is released. In some embodiments, if the terminal device 110 does not have any active spatial relationships to the PUCCH resource after the TAT expires in SpCell, the terminal device 110 considers all TATs to have expired.

[0054] The network device 120 performs operations corresponding to the terminal device 110. In block 222, the network device 120 determines at least two TAGs for the serving cell. The at least two TAGs include a primary TAG and a secondary TAG that correspond to the TAGs in the terminal device 110. The network device 120 may send a control signal to the terminal device 110 indicating which TAG is the primary TAG, for example, the TAG with the lower TAG ID. Furthermore, the network device 120 is also aware of the expiration of the TATs of the primary and secondary TAGs, and if the TAT of the original primary TAG expires, it can determine the secondary TAG as the new primary TAG.

[0055] In block 224, the network device 120 determines whether at least one time alignment timer (TAT) of at least two TAGs has expired. The network device 120 uses the TAT to determine whether the terminal device 110 is in a synchronized state. When a TAG's TAT ​​expires, the network device 120 recognizes that the TA value of the corresponding TAG has become invalid. In this case, the network device 120 performs the RACH procedure and sends a new TAC to the terminal device.

[0056] In block 226, the network device 120 determines, based on its determination that at least one TAT has expired, one of the primary and secondary TAGs to be maintained in the terminal device. In this way, the network device 120 is aware of the expiration of the TAT, understands the operation of the terminal device 110, and can respond accordingly.

[0057] In 230, the terminal device 110 and the network device 230 may perform a RACH procedure, in which a TAC is sent from the network device 120 to the terminal device 110 in a Random Access Response (RAR). This RACH procedure may be triggered by the terminal device 110 using a PRACH preamble, or by the network device 120 using a PDCCH order.

[0058] Subsequently, upon receiving a TAC via RAR, terminal device 110 applies the TAC to the primary TAG regardless of the SSB selected for random access, provided that an RA procedure is triggered at terminal device and no TATs are currently in progress. Terminal device 110 may apply the TAC to the primary TAG based on the determination that a RACH procedure has been triggered at terminal device 110 or that at least one TAT of at least two TAGs has expired.

[0059] In some embodiments, when a PDCCH order for a RACH procedure is triggered to terminal device 110 and the target DL RS is associated with a specific TAG ID, terminal device 110 may associate the TAG ID of the TCI state used to schedule the PDCCH order with the primary TAG. Implicitly, if terminal device 110 is indicated as a second / other TCI state, terminal device 110 may associate the TAG ID of that TCI state (if it differs from the TAG ID of the primary TAG) with the secondary TAG. In some embodiments, the TAG ID may be associated with the TCI state used to send the PDCCH order for RACH, or with the TAG ID corresponding to the PCI indicated in the PDCCH order.

[0060] In some embodiments, the terminal device 110 may be configured to store primary and secondary tags associated with TAG IDs (of different TCI states) and corresponding TA values. In some embodiments, the random access response provided for RA preamble transmission may include a notification to the terminal device whether it can apply the stored values ​​and TA values ​​for the primary and secondary tag association. If the network triggers a PDCCH order associated with the TCI state of the secondary tag and receives a TAC in the response that sends a notification to apply the TAG ID associated with the stored TA value, the terminal device may decide to apply the previous setting. If the response does not include that information, the terminal device may assume that the TAC was applied to the TAG ID associated with the TCI state and associate the TAG ID with the primary tag.

[0061] In 232, the terminal device may perform a UL transmission. In some embodiments, the UE may use beam for the UL transmission used for PRACH preamble transmission until it receives an update to the Transmit Configuration Information (TCI) status from the network (e.g., via RRC reconfiguration or MAC CE).

[0062] Based on the above, it can be seen that when a terminal device has a single TAT in operation or does not have a TAT, only a single TAG is maintained, eliminating ambiguity in RA procedure / UL signal transmission. Since the network is aware of the expiration of the TAT, it can recognize the operation of the terminal device and respond accordingly.

[0063] Figure 3 shows a flowchart of an exemplary method 300 implemented in a terminal device according to other embodiments of the present disclosure. For ease of understanding, method 300 will be described with reference to Figure 1, in view of the terminal device 110.

[0064] In block 310, the terminal device 110 determines at least two TAGs for a serving cell, the at least two TAGs including a primary TAG and a secondary TAG. Based on a setting indicating a primary TAG, the terminal device 110 may determine one of the TAGs as the primary TAG. Additionally or alternatively, based on determining that the TAT of the primary TAG has expired, the terminal device 110 may determine a secondary TAG with an active TAT as the primary.

[0065] In block 320, the terminal device 110 determines whether at least one TAT of at least two TAGs has expired. The terminal device 110 takes the TAT for each TAG and detects whether the TAT has expired. Upon detecting that the TAT has expired, the terminal device 110 recognizes that synchronization has been lost for the corresponding TAG ID. In some embodiments, the serving cell may include a primary cell, a primary secondary cell, or a secondary cell with multiple TRPs.

[0066] In block 330, the terminal device 110 maintains one of the primary TAG and secondary TAG based on the determination that at least one TAT has expired. In some embodiments, the terminal device 110 may release the secondary TAG setting associated with the secondary TAG. The secondary TAG setting may be released when the TATs associated with at least two TAGs expire. Additionally or alternatively, the secondary TAG setting may be released when one of the TATs associated with the primary TAG or the TAT associated with the secondary TAG expires.

[0067] In some embodiments, the terminal device 110 releases the physical uplink control channel (PUCCH) resource associated with the secondary TAG. Additionally or alternatively, the terminal device 110 releases the sounding reference signal (SRS) resource associated with the secondary TAG. Additionally or alternatively, the terminal device 110 clears the configured downlink assignment and configured uplink grant associated with the secondary TAG. Additionally or alternatively, the terminal device 110 may clear the physical uplink shared channel (PUSCH) resource for semi-persistent channel status information (CSI) reporting associated with the secondary TAG.

[0068] In some embodiments, the terminal device 110 can disable the spatial relationship of the uplink (UL) signal associated with the secondary TAG. Thus, the spatial relationship associated with the secondary TAG is suspended.

[0069] In some embodiments, the terminal device 110 may receive a Timing Advance Command (TAC) in the Random Access Response (RAR) of a Random Access Channel (RACH) procedure. Based on the determination that a RACH procedure has been triggered in the terminal device, or that at least one TAT of at least two TAGs has expired, the terminal device 110 may apply the TAC to the primary TAG.

[0070] In some embodiments, the terminal device 110 applies a beam for UL transmission used for physical random access channel (PRACH) preamble transmission until it receives an update to the transmit setting indicator (TCI) state, and this UL transmission has a timing advance indicated by TAC.

[0071] In some embodiments, the terminal device 110 may store a first TAG ID and a first TA value associated with a primary TAG, and a second TAG ID and a second TA value associated with a secondary TAG. In some embodiments, one or more of the first and second TAG IDs may be associated with a PDCCH order for a RACH procedure triggered to the terminal device 110. Additionally or alternatively, one or more of the first and second TAG IDs may be associated with a PCI indicated in the PDCCH order. Additionally or alternatively, one or more of the first and second TAG IDs may be associated with a TCI state used to send the PDCCH order.

[0072] In some embodiments, the terminal device 110 may receive a RAR provided for the transmission of a PDCCH order. Based on the received RAR, the terminal device 110 applies one of the first TA values ​​associated with the primary TAG and the second TA value associated with the secondary TAG.

[0073] In some embodiments, the terminal device 110 may apply a second TA value associated with the secondary TAG based on its determination that the RAR includes a notification to the secondary TAG. The terminal device 110 may apply a first TA value associated with the primary TAG based on its determination that the RAR does not include a notification to the secondary TAG.

[0074] Figure 4 is a flowchart showing examples of other methods implemented in a network device according to some embodiments of the present disclosure. For ease of understanding, Method 400 will be described with reference to Figure 1, in view of a terminal device 120.

[0075] In block 410, the network device 120 determines at least two TAGs for the serving cell, the at least two TAGs including a primary TAG and a secondary TAG. In block 420, the network device 120 determines whether at least one TAT of the at least two TAGs has expired. In block 430, based on the determination that at least one TAT has expired, the network device 120 determines one of the primary TAG and secondary TAG to be maintained at the terminal device. In some embodiments, the serving cell may include a primary cell, a primary-secondary cell, or a secondary cell having multiple TRPs.

[0076] In some embodiments, the network device 120 stores a first TAG ID and a first TA value associated with the primary TAG, and stores a second TAG ID and a second TA value associated with the secondary TAG.

[0077] In some embodiments, one or more of the first and second TAG IDs are associated with a PDCCH order for a RACH procedure triggered to the terminal device 110. Additionally or alternatively, one or more of the first and second TAG IDs are associated with a PCI indicated in the PDCCH order. Additionally or alternatively, one or more of the first and second TAG IDs may be associated with a TCI state used to transmit the PDCCH order.

[0078] In some embodiments, the network device 120 transmits the RAR provided for the transmission of the PDCCH order to the terminal device. The RAR may include a notification indicating whether the primary TAG or the secondary TAG should be applied by the terminal device.

[0079] In some embodiments, an apparatus capable of performing Method 300 (e.g., terminal device 110) comprises means for performing each step of Method 300. These means can be implemented in any suitable form. For example, these means can be implemented as a circuit or a software module.

[0080] In some embodiments, the apparatus comprises means for determining at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG; means for determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired; and means for maintaining one of the primary TAG and the secondary TAG based on the determination that at least one TAT has expired.

[0081] In some embodiments, the device may include means for determining the primary TAG of at least two TAGs based on at least one of the following: setting a primary TAG, or determining a secondary TAG with an active TAT as primary based on determining that the TAT of the primary TAG has expired.

[0082] In some embodiments, the device may include means for releasing the secondary TAG setting associated with the secondary TAG.

[0083] In some embodiments, the means for releasing the secondary TAG setting may include means for releasing the secondary TAG based on at least one of the following: the expiration of TATs associated with at least two TAGs, the expiration of TATs associated with the primary TAG, or the expiration of TATs associated with the secondary TAG.

[0084] In some embodiments, means for releasing secondary TAG settings may include means for releasing physical uplink control channel (PUCCH) resources associated with the secondary TAG, means for releasing sounding reference signal (SRS) resources associated with the secondary TAG, means for clearing configured downlink assignments and configured uplink grants associated with the secondary TAG, and means for clearing physical uplink shared channel (PUSCH) resources for semi-persistent channel status information (CSI) reporting associated with the secondary TAG.

[0085] In some embodiments, the device may include means for disabling the spatial relationships of uplink (UL) signals associated with the secondary TAG.

[0086] In some embodiments, the device may include means for receiving a timing advance command (TAC) in a random access response (RAR) of a random access channel (RACH) procedure, and means for applying the TAC to a primary TAG based on determining whether the RACH procedure was triggered at a terminal device or whether at least one TAT of at least two TAGs has expired.

[0087] In some embodiments, the apparatus includes means for applying a beam for UL transmission used for physical random access channel (PRACH) preamble transmission until it receives a transmit setting indicator (TCI) state update, and the UL transmission has a timing advance indicated in the TAC.

[0088] In some embodiments, the device may include means for storing a first TAG ID and a first TA value associated with a primary TAG, and means for storing a second TAG ID and a second TA value associated with a secondary TAG.

[0089] In some embodiments, at least one of the first TAG ID and the second TAG ID is associated with at least one of the following: a physical downlink control channel (PDCCH) order for a RACH procedure triggered on a terminal device, a physical cell ID (PCI) indicated by the PDCCH order, or a transmit configuration indicator (TCI) state used to transmit the PDCCH order.

[0090] In some embodiments, the apparatus may include means for receiving a RAR provided for transmitting a PDCCH order, and means for applying, based on the received RAR, one of a first TA value associated with a primary TAG and a second TA value associated with a secondary TAG.

[0091] In some embodiments, the device may include means for applying a second TA value associated with a secondary TAG based on the determination that the RAR includes a notification to the secondary TAG, and means for applying a first TA value associated with the primary TAG based on the determination that the RAR does not include a notification to the secondary TAG.

[0092] In some embodiments, the serving cell includes a primary cell, a primary-secondary cell, or a secondary cell having multiple transmit / receive points (TRPs).

[0093] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of Method 300. In some embodiments, the means comprises at least one processor and at least one memory containing computer program code, wherein the at least one memory and the computer program code are configured to cause the apparatus to perform operations by the at least one processor.

[0094] In some embodiments, an apparatus capable of performing Method 400 (e.g., a network device 120) may include means for performing each step of Method 400. These means can be implemented in any suitable form. For example, these means can be implemented as a circuit or a software module.

[0095] In some embodiments, the device may include means for determining at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG; means for determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired; and means for determining, based on the determination that at least one TAT has expired, one of the primary TAG and secondary TAG to be maintained in the terminal device.

[0096] In some embodiments, the device may include means for determining a primary TAG based on at least one of the following: a setting indicating a primary TAG, or means for determining a secondary TAG having a running TAT as primary based on the determination that the TAT of the primary TAG has expired.

[0097] In some embodiments, the device may include means for storing a first TAG ID and a first TA value in association with a primary TAG, and means for storing a second TAG ID and a second TA value in association with a secondary TAG.

[0098] In some embodiments, at least one of the first tag ID and the second tag ID is associated with at least one of the following: a physical downlink control channel (PDCCH) order for a RACH procedure triggered to a terminal device, a physical cell ID (PCI) indicated in the PDCCH order, or a transmit setting indicator (TCI) state used to transmit the PDCCH order.

[0099] In some embodiments, the apparatus may include means for transmitting a RAR provided for the transmission of a PDCCH order to a terminal device, the RAR including a notice indicating whether the primary TAG or the secondary TAG should be applied at the terminal device.

[0100] In some embodiments, the serving cell includes a primary cell, a primary-secondary cell, or a secondary cell having multiple transmit / receive points (TRPs).

[0101] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of Method 400. In some embodiments, the means comprises at least one processor and at least one memory containing computer program code, wherein the at least one memory and the computer program code are configured to cause the apparatus to perform operations by the at least one processor.

[0102] Figure 5 shows a simplified block diagram of a device 500 suitable for implementing some embodiments of the present disclosure. The device 500 is provided for implementing communication devices such as the network device 120 and terminal device 110 shown in Figure 1. As shown in the figure, the device 500 comprises one or more processors 510, one or more memories 520 connected to the processors 510, and one or more communication modules 540 connected to the processors 510.

[0103] The communication module 540 is for bidirectional communication. To facilitate communication, the communication module 540 is equipped with at least one antenna. The communication interface can represent any interface necessary for communication with other network elements.

[0104] The processor 510 is of any type suitable for a local technology network and may include, for example, a general-purpose computer, a dedicated computer, a microprocessor, a digital signal processor (DSP), or a processor based on a multi-core processor architecture. The device 500 may have multiple processors, such as application-specific integrated circuit chips that are time-dependent to a clock that synchronizes the main processor.

[0105] The memory 520 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) 524, electrically rewritable read-only memory (EPROM), flash® memory, hard disks, compact discs (CDs), digital video discs (DVDs), and other magnetic and / or optical storage devices. Examples of volatile memories include random-access memory (RAM) 522 and other volatile memories that cannot retain data during power outages.

[0106] The computer program 530 includes computer executable instructions that are executed by the associated processor 510. The program 530 may be stored in the ROM 524. The processor 510 performs any appropriate operations and processes by loading the program 530 into the RAM 522.

[0107] Embodiments of the present disclosure are implemented by program 530, enabling the device 500 to perform any process of the present disclosure described with reference to Figures 3 and 4. Embodiments of the present disclosure may also be implemented by hardware, or by a combination of software and hardware.

[0108] In some embodiments, the program 530 may be tangibly stored in a computer-readable medium built into the device 500 (for example, in the memory 520) or in another storage device accessible to the device 500. The device 500 can load the program 530 from the computer-readable medium into the RAM 522 and execute it. The computer-readable medium may include any type of tangible non-volatile storage device, such as ROM, EPROM, flash® memory, hard disk, CD, DVD, etc.

[0109] Figure 6 is a block diagram showing an example of a computer-readable medium 600 according to some embodiments of the present disclosure. The computer-readable medium 600 stores a program 530. Note that although the computer-readable medium 600 is shown in the form of a CD or DVD in Figure 5, it may be in other forms suitable for transporting or holding the program 530.

[0110] In general, various embodiments of this disclosure may be implemented in hardware or dedicated circuitry, software, logic, or any combination thereof. Some features may be implemented in hardware, while others may be implemented in firmware or software that can be executed by a controller, microprocessor, or other computing device. Various aspects of the embodiments described herein are illustrated using block diagrams, flowcharts, or other graphic representations, but it should be understood that the blocks, devices, systems, techniques, or methods described herein may be implemented, in non-limiting examples, in hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controllers or other computing devices, or a combination thereof.

[0111] This disclosure also provides at least one computer program product physically recorded on a non-temporary computer-readable storage medium. This computer program product includes computer-executable instructions, such as those contained in a program module, which are executed on a device on a target real or virtual processor to perform the methods 300 or 400 described above with reference to Figure 3 or 4. Generally, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc., that perform a specific task or implement a specific abstract data type. The functionality of the program modules is combined or divided among the program modules as needed in various embodiments. The machine-executable instructions for the program modules are executed in local or distributed devices. In distributed devices, the program modules reside on both local and remote storage media.

[0112] Program code for carrying out the methods of this disclosure is written in any combination of one or more programming languages. These program codes are provided to a processor or controller of a general-purpose computer, a dedicated computer, or other programmable data processing device, and are executed by the processor or controller to implement the functions / operations specified in the flowcharts and / or block diagrams. The program code may run entirely on the machine, partially on the machine, run as a standalone software package, partially on the machine and partially on a remote machine, or run entirely on a remote machine or server.

[0113] In the context of this disclosure, computer program code or related data may be carried by any suitable medium to enable a device, apparatus, or processor to perform various processes and operations as described above. Examples of such mediums include signals and computer-readable media.

[0114] Computer-readable media may be computer-readable signal media or computer-readable storage media. Computer-readable media include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, and semiconductor systems, apparatus, devices, or appropriate combinations thereof. More specific examples of computer-readable storage media include electrical connections with one or more wires, portable computer floppy disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash® memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or appropriate combinations thereof. The term "non-temporary" as used herein refers to a limitation on the medium itself (i.e., a tangible medium rather than a signal) and not on the persistence of data storage (e.g., RAM vs. ROM).

[0115] Furthermore, even if operations are shown in a specific order, this should not be interpreted as meaning that the operations must be performed in that specific order or sequential order, or that all illustrated operations must be performed, in order to obtain the desired result. In certain situations, multitasking or parallel processing may be advantageous. Similarly, although the above discussion includes some specific implementation details, these should not be interpreted as limitations on the scope of this disclosure, but rather as descriptions of features specific to particular embodiments. Certain features described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable partial combination in multiple embodiments.

[0116] While this disclosure is described in a language specific to structural features and / or methodological actions, the disclosure as defined in the attached claims is not necessarily limited to the specific functions or actions described above. Rather, the specific functions or actions described above are disclosed as exemplary forms of implementing the claims.

Claims

1. A terminal device, At least one processor, When executed by the at least one processor, the terminal device will have at least, Determining at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG, Determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired, Based on the determination that at least one of the TATs has expired, maintain one of the primary TAGs and the secondary TAGs, At least one memory to store instructions to execute, A terminal device equipped with the following features.

2. The aforementioned terminal device further, The setting indicating the primary TAG, or Based on the determination that the TAT of the primary TAG has expired, the secondary TAG having an ongoing TAT is determined to be the primary. The terminal device according to claim 1, wherein the primary TAG of the at least two TAGs is determined based on at least one of the following.

3. The aforementioned terminal device further, Release the secondary TAG setting associated with the aforementioned secondary TAG. The terminal device according to claim 1 or 2, wherein the device is configured to be such as.

4. The aforementioned terminal device further, Expiration of TAT associated with at least two of the aforementioned TAGs, Expiration of the TAT associated with the aforementioned primary TAG, or Expiration of TAT associated with the aforementioned secondary TAG, The terminal device according to claim 3, wherein the secondary TAG setting is released based on at least one of the following.

5. The aforementioned terminal device further, To release the physical uplink control channel (PUCCH) resource associated with the secondary TAG, To release the sounding reference signal (SRS) resource associated with the secondary TAG, To clear the configured downlink assignment and configured uplink grant associated with the secondary TAG, or To release the physical uplink shared channel (PUSCH) resource for reporting semi-persistent channel status information (CSI) associated with the secondary TAG, The terminal device according to claim 3 or 4, wherein the secondary TAG setting is released by at least one of the following.

6. The aforementioned terminal device further, To disable the spatial relationship of the uplink (UL) signal associated with the secondary TAG, A terminal device according to any one of claims 1 to 5, wherein the device is configured to be such as.

7. The aforementioned terminal device further, Receiving a Timing Advance Command (TAC) in the Random Access Response (RAR) of a Random Access Channel (RACH) procedure, Based on the determination that the RACH procedure has been triggered in the terminal device, or that at least one TAT of the at least two TAGs has expired, the TAC is applied to the primary TAG. A terminal device according to any one of claims 1 to 6, which is configured to perform the following:

8. The aforementioned terminal device further, Applying the UL transmit beam used for physical random access channel (PRACH) preamble transmission until a Transmit Setting Indicator (TCI) status update is received, wherein the UL transmit has the timing advance indicated by the TAC. The terminal device according to claim 7, which is configured to perform the following.

9. The aforementioned terminal device further, The first TAG ID and the first Timing Advance (TA) value are stored in association with the primary TAG, The second TAG ID and the second TA value are stored in association with the aforementioned secondary TAG, A terminal device according to any one of claims 1 to 8, which is configured to perform the following:

10. At least one of the first TAG ID and the second TAG ID is A physical downlink control channel (PDCCH) order for a RACH procedure triggered on the terminal device, The physical cell ID (PCI) indicated by the PDCCH order, or The state of the Transmit Setting Indicator (TCI) used for transmitting the PDCCH order, The terminal device according to claim 9, which is associated with at least one of the following.

11. The aforementioned terminal device further, Receiving the RAR provided for the transmission of the PDCCH order, Based on the received RAR, one of the first TA value associated with the primary TAG and the second TA value associated with the secondary TAG is applied, The terminal device according to claim 10, which is configured to perform the following.

12. The aforementioned terminal device further, Based on the determination that the RAR includes notification to the secondary TAG, the second TA value associated with the secondary TAG is applied, Based on the determination that the RAR does not include the notification to the secondary TAG, the first TA value associated with the primary TAG is applied, The terminal device according to claim 11, which is configured to perform the following.

13. The serving cell includes a primary cell, a primary secondary cell, or a secondary cell having multiple transmit / receive points (TRPs). The terminal device according to any one of claims 1 to 12.

14. Network device, At least one processor, When executed by the at least one processor, the network device will have at least, Determining at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG, Determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired, Based on the determination that at least one of the TATs has expired, the terminal device determines which of the primary TAGs and secondary TAGs should be maintained. At least one memory to store instructions to execute, A network device equipped with the following features.

15. The aforementioned network device further, The setting indicating the primary TAG, or Based on the determination that the TAT of the primary TAG has expired, the secondary TAG having an ongoing TAT is determined to be the primary. The network device according to claim 14, wherein the primary TAG is determined based on at least one of the following.

16. The aforementioned network device further, The first TAG ID and the first timing advance (TA) value associated with the primary TAG are stored, The second TAG ID and the second TA value are stored in relation to the aforementioned secondary TAG, The network device according to claim 14 or 15, which is configured to perform the following.

17. At least one of the first TAG ID and the second TAG ID is A physical downlink control channel (PDCCH) order for a RACH procedure triggered in the aforementioned network device, The physical cell ID (PCI) indicated by the PDCCH order, or The state of the Transmit Setting Indicator (TCI) used for transmitting the PDCCH order, A network device according to claim 16, associated with the above.

18. The aforementioned network device further, Transmitting a RAR provided for the transmission of the PDCCH order to the terminal device, wherein the RAR includes a notification to the terminal device whether the primary TAG should be applied or the secondary TAG should be applied. The network device according to claim 17, which is configured to perform the following.

19. The serving cell includes a primary cell, a primary secondary cell, or a secondary cell having multiple transmit / receive points (TRPs). A network device according to any one of claims 14 to 18.

20. Determining at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG, Determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired, Based on the determination that at least one of the TATs has expired, maintain one of the primary TAGs and the secondary TAGs, Methods that include...

21. Determining at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG, Determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired, Based on the determination that at least one of the TATs has expired, the terminal device determines which of the primary TAGs and secondary TAGs should be maintained. Methods that include...

22. Means for determining at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG; Means for determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired, Means for maintaining one of the primary TAG and the secondary TAG based on the determination that at least one TAT has ended, A device equipped with the following features.

23. Means for determining at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG; Means for determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired, Means for determining one of the primary TAG and the secondary TAG to be maintained in the terminal device based on the determination that at least one of the TATs has expired, A device equipped with the following features.

24. A non-temporary computer-readable medium, which, when executed by a device, provides to the device at least: Determining at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG, Determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired, Based on the determination that at least one of the TATs has expired, maintain one of the primary TAGs and the secondary TAGs, A non-temporary computer-readable medium containing program instructions that cause something to be executed.

25. A non-temporary computer-readable medium, which, when executed by a device, provides to the device at least: Determining at least two timing advance groups (TAGs) for a serving cell, wherein the at least two TAGs include a primary TAG and a secondary TAG, Determining whether at least one time alignment timer (TAT) of the at least two TAGs has expired, Based on the determination that at least one of the TATs has expired, the terminal device determines which of the primary TAGs and secondary TAGs should be maintained. A non-temporary computer-readable medium containing program instructions that cause something to be executed.

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