Multiple tag expiration handling

Description

1 / 29 MULTIPLE TAG EXPIRATION HANDLING FIELD

[0001] Exemplary embodiments of the present disclosure relate generally to the field of communication and, in particular, to a terminal device, a network device, methods, apparatus and a computer-readable means for handling the expiration of at least one time alignment timer (TAT) of multiple timing advance groups (TAGs) associated with a service cell. BACKGROUND

[0002] In New Radio (NR) systems, the concept and functionality of NR timing advance (TA) are substantially the same as long-term evolution (LTE) timing advance. In short, TA is a special command (e.g., notification) from a network device to a terminal device that enables the terminal device to adjust its uplink transmission. This type of uplink adjustment can apply to uplink shared physical channel (PUSCH), uplink control physical channel (PUCCH), probe reference signal (SRS), etc.

[0003] In 3GPP release 18, it was agreed to offer support for the enhancement of two TAs for multiple downlink (DCI) and uplink (UL) control information for multiple transmit / receive point (TRP) operation. However, solutions related to multiple TAs need to be studied further. SUMMARY

[0004] In general, exemplary embodiments of the present disclosure provide solutions for handling multiple timing advance values ​​for user equipment (UE) within a service cell.

[0005] In a first aspect, a terminal device is provided. The terminal device comprises at least one processor and at least one memory that stores instructions which, when executed by at least one processor, cause the terminal device to at least: determine at least two advance groups of Petition 870250090930, dated 06 / 10 / 2025, page 10 / 90 2 / 29 timing (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on determination that at least one TAT has expired, one of the primary TAG and one of the secondary TAG.

[0006] In a second aspect, a network device is provided. The network device comprises: at least one processor; and at least one memory that stores instructions which, when executed by the at least one processor, cause the network device to at least: determine at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on determination that at least one TAT has expired, that one of the primary TAG and one of the secondary TAG is held in a terminal device.

[0007] In a third aspect, a method is provided. The method comprises: determining, in a terminal device, at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on the determination that at least one TAT has expired, one of the primary TAG and one of the secondary TAG.

[0008] In a fourth aspect, a method is provided. The method comprises: determining, on a network device, at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, that one of the primary TAG and one of the secondary TAG is maintained on a terminal device.

[0009] In a fifth aspect, an apparatus is provided. The apparatus comprises: means for determining, in a terminal device, at least two advance groups of Petition 870250090930, dated 06 / 10 / 2025, page 11 / 90 3 / 29 timing (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on determination that at least one TAT has expired, one of the primary TAG and one of the secondary TAG.

[0010] In a sixth aspect, an apparatus is provided. The apparatus comprises: means for determining, in a network device, at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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 determination that at least one TAT has expired, that one of the primary TAG and one of the secondary TAG is maintained in a terminal device.

[0011] In a seventh aspect, a non-transient, computer-readable storage medium is provided comprising program instructions. The program instructions, when executed by an apparatus, cause the apparatus to perform at least the following: determine at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on determination that at least one TAT has expired, one of the primary TAG and one of the secondary TAG.

[0012] In an eighth aspect, a non-transient, computer-readable storage medium is provided comprising program instructions. The program instructions, when executed by an apparatus, cause the apparatus to perform at least the following: determine at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on determination that at least one TAT has expired, that one of the primary TAG and one of the secondary TAG is held in a terminal device. Petition 870250090930, dated 06 / 10 / 2025, page 12 / 90 4 / 29

[0013] In a ninth aspect, a computer program is provided comprising instructions that, when executed by an apparatus, cause the apparatus to at least: determine at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on determination that at least one TAT has expired, one of the primary TAG and one of the secondary TAG.

[0014] In a tenth aspect, a computer program is provided comprising instructions that, when executed by an apparatus, cause the apparatus to at least: determine at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on determination that at least one TAT has expired, that one of the primary TAG and one of the secondary TAG is held in a terminal device.

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

[0016] In a twelfth aspect, a network device is provided. The network device comprises: a first set of circuits configured to determine at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise a primary TAG and a secondary TAG; a second set of circuits configured to determine whether at least one time alignment timer (TAT) of the at least two TAGs Petition 870250090930, dated 06 / 10 / 2025, page 13 / 90 5 / 29 expired; and a third set of circuits configured to determine, based on the determination that at least one TAT has expired, which of the primary TAG and secondary TAGs is maintained in a terminal device.

[0017] It should be understood that the summary section is not intended to identify key or essential attributes of the modalities of this disclosure, nor is it intended to be used to limit the scope of this disclosure. Other attributes of this disclosure will become easily understandable through the description that follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Some exemplary embodiments will now be described with reference to the accompanying drawings, in which:

[0019] FIG. 1 illustrates an exemplary communication network in which modalities of the present disclosure can be implemented;

[0020] FIG. 2 illustrates an example of process flow according to some exemplary embodiments of the present disclosure;

[0021] FIG. 3 illustrates a flowchart of an exemplary method implemented in a terminal device according to some embodiments of the present disclosure;

[0022] FIG. 4 illustrates another flowchart of an exemplary method implemented in a network device according to some embodiments of the present disclosure;

[0023] FIG. 5 illustrates a simplified block diagram of a device that is suitable for implementing some exemplary embodiments of the present disclosure; and

[0024] FIG. 6 illustrates a block diagram of an example of a computer-readable medium according to some exemplary embodiments of the present disclosure.

[0025] Throughout the drawings, the same reference numbers or similar reference numbers represent the same element or similar elements. DETAILED DESCRIPTION

[0026] The principle of the present revelation will now be described with reference to some exemplary modalities. It should be understood that these modalities are described only for the purpose of illustration and assistance to those skilled in the art. Petition 870250090930, dated 06 / 10 / 2025, p. 14 / 90 6 / 29 understand and implement this disclosure, without suggesting any limitation to the scope of the disclosure. The disclosure described in this document may be implemented in several ways different from those described below.

[0027] In the description and claims that follow, unless otherwise defined, all technical and scientific terms used herein have the same meaning commonly understood by a person with common knowledge of the art to which this disclosure pertains.

[0028] References in this disclosure to a (1) embodiment, a embodiment, an exemplary embodiment and the like indicate that the embodiment described may include a particular attribute, structure or feature, but it is not necessary that every embodiment include the particular attribute, structure or feature. Furthermore, such expressions do not necessarily refer to the same embodiment. In addition, when a particular attribute, structure or feature is described together with an embodiment, it is stated that it is known to one skilled in the art to affect that attribute, structure or feature together with other embodiments, whether they are explicitly described or not.

[0029] It should be understood that, although the terms “first” and “second,” etc., may be used in this document to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element may be called a second element, and similarly, a second element may be called a first element, without departing from the scope of illustrative modalities. As used in this document, the term “and / or” includes any and all combinations of one or more of the terms listed.

[0030] The terminology used in this document is intended to describe particular modalities only and is not intended to be limiting of exemplary modalities. As used in this document, the singular forms “a”, “an”, “the” and “the” are intended to also include the plural forms, unless the context clearly indicates otherwise. It will additionally be understood that the terms “comprises”, “that includes”, “has”, “that has”, “includes” and / or “that includes”, when Petition 870250090930, dated 06 / 10 / 2025, p. 15 / 90 7 / 29 used in this document specify the presence of declared attributes, elements and / or components, etc., but do not exclude the presence or addition of one or more other attributes, elements, components and / or combinations thereof. As used in this document, “at least one of the following:<uma lista de dois ou mais elementos> "and at least one of<uma lista de dois ou mais elementos> "And a similar expression, in which the list of two or more elements is joined by 'and' or 'or', means at least any one of the elements, or at least any two or more of the elements, or at least all of the elements."

[0031] As used in this application, the term circuit set may refer to one, more, or all of the following: (a) hardware-only circuit implementations (such as analog-only and / or digital-only circuit implementations) and (b) combinations of hardware and software circuits, such as (where applicable): (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s), software and memory(ies) that work together to make a device, such as a server or mobile phone, perform various functions) and (c) hardware circuit(s) and / or processor(s), such as microprocessor(s) or a portion of microprocessor(s), that require software (e.g., firmware) for operation, but the software may not be present when it is not required for operation.

[0032] This definition of circuit assembly applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuit assembly also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or its) accompanying software and / or firmware. The term circuit assembly also covers, for example, and if applicable to the particular claim element, a baseband integrated circuit. Petition 870250090930, dated 06 / 10 / 2025, page 16 / 90 8 / 29 or integrated processor circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or networking device.

[0033] As used in this document, the term “network,” “communication network,” or “data network” refers to a network that follows any suitable communication standards, such as Long Term Evolution (LTE), LTE Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), Wireless Fidelity (Wi-Fi), and so forth. Furthermore, communications between a terminal device and a network element / device on the communication network may be carried out in accordance with any suitable generation network protocols, including, but not limited to, fourth-generation (4G), 4.5G, future fifth-generation (5G) communication protocols, IEEE 802.11, and / or any other protocols currently known or to be developed in the future. Embodiments of this disclosure may be applied in various communication systems.Given the rapid development of communications, it is clear that there will also be future types of technologies and communication systems into which the present disclosure may be incorporated. This should not be seen as limiting the scope of the present disclosure only to the system mentioned above.

[0034] As used in this document, the term network device refers to a node in a communication network through which a terminal device accesses the network and receives services from it. The network device may refer to a base station (BS) or an access point (AP) or a transmit / receive point (TRP), for example, a B node (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), a WiFi device, a repeater, a low-power node such as a femto, a pico, and so on, 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. Petition 870250090930, dated 06 / 10 / 2025, p. 17 / 90 9 / 29

[0035] The term “terminal device” refers to any endpoint device that is capable of wireless communication. By way of example and without limitation, a terminal device may also be called a communication device, user equipment (UE), Subscriber Station (SS), Portable Subscriber Station, Mobile Station (MS), a station (STA) or station device, or an Access Terminal (AT). The terminal device may include, but is not limited to, a mobile phone, a cellular phone, a smartphone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), laptops, desktop computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback devices, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations,Laptop embedded equipment (LEE), laptop mounted equipment (LME), USB dongles, smart devices, wireless customer premises equipment (CPE), an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in industrial and / or automated processing chain contexts), a consumer electronic device, a device operating on commercial and / or industrial wireless networks, and similar devices. In the following description, the terms “station”, “station device”, “STA”, “terminal device”, “communication device”, “terminal”, “user equipment”, and “UE” may be used interchangeably.

[0036] As used in this document, the term “TRP” refers to a transmit and receive point that has an antenna array (with one or more antenna elements) on the network side located at a specific geographic location, which can be used to transmit and receive signals to / from the terminal device. In embodiments of this disclosure, a TRP may refer to a macrocell, microcell, an RRH, a repeater, a femto node, a pico node, etc. Although some embodiments of this disclosure are described with reference to two TRPs, for example, these Petition 870250090930, dated 06 / 10 / 2025, p. 18 / 90 10 / 29 embodiments are for illustrative purposes only and to assist those skilled in the art in understanding and implementing the present disclosure, without suggesting any limitations to the scope of the present disclosure. It should be understood that the present disclosure described herein can be implemented in a variety of ways beyond those described below.

[0037] As discussed above, TA is a special command (e.g., notification) from a network device to a terminal device that enables the terminal device to adjust its uplink transmission. TA is a special command (e.g., notification) from the network device to the terminal device that enables the terminal device to adjust its uplink transmission.

[0038] TA can be delivered to a terminal device via Random Access Response (RAR) or MAC CE (Media Access Control Element). A TA loop can be used to maintain TA to enable alignment of UL signals (transmitted from a terminal device) at a network node within a certain time resolution. In a random access procedure, the terminal device may receive an initial TA value (e.g., an absolute TA value) in a RAR message. The TA value can then be updated with a MAC CE containing a timing advance command (TAC) indicating a relative TA value. Additionally, the UE can also autonomously update TA upon initial request for an updated TA value. These TA maintenance operations are called a TA loop. Usually, a TA loop can correspond to UL transmissions towards a given TRP.Furthermore, a TA loop can correspond to the TA held within a TAG. Therefore, a TA loop can correspond to a TA, and the number of TA loops can indicate the number of TAs used. Thus, in the present disclosure, a TA loop can implicitly refer to a TA.

[0039] A timing advance group (TAG) used in this document means that a group consists of one or more service cells with the same uplink TA and the same downlink timing reference cell. Each TAG contains at least one service cell with an uplink configured, and the mapping of each service cell to a TAG is Petition 870250090930, dated 06 / 10 / 2025, page 19 / 90 11 / 29 configured by a Radio Resource Control (RRC) signal. In 3GPP release 18, it was already agreed to offer NR system support for two TAs for multi-DCI UL multi-TRP operation. Furthermore, support for two TA enhancements was agreed for multi-DCI multi-TRP scenarios both intra-cell and inter-cell in 3GPP release 18. Multiple (two or more) timing advance values ​​for a UE within a service cell are under discussion for further enhancements (NR).

[0040] Since in the multi-TRP scenario the UE could have 2 TAGs for a service cell (like SpCell), these TAGs would naturally employ different time alignment timers (TATs) so that the network (NW) would be able to provide separate time adjustment commands using, for example, TAC MAC CE and therefore the TATs can be (re)started at different times for these two TAGs.

[0041] Although the UE in RRC_CONNECTED mode is configured with 2 TA / TAG loops for a Service Cell, and more specifically, for a SpCell (PCell / PSCell), the TATs associated with the TAGs may expire at different times. One of the TAGs associated with the SpCell may be considered a primary TAG and one may be considered a secondary TAG. It is unclear what the UE's behavior is when both or one of these timers expire.

[0042] According to embodiments of the present disclosure, a solution is provided for handling multiple TAGs upon expiration of a TAT associated with a service cell. The UE can have at least two TAGs for a service cell comprising a primary TAG and a secondary TAG. When at least one of the service cell's TATs (e.g., SpCell) expires, the UE retains only the primary TAG. Which is the primary TAG of the cell group / SpCell can be pre-configured, or the TAG with a TAT still running can become the primary TAG if only one TAT expires for the SpCell TAGs. In this way, only a single TAG is retained since the UE has a single TAT / no TAT running, removing ambiguities in RA procedures / UL signal transmissions. Since NW is aware of the TAT expiration, it knows the UE's behavior and can act accordingly. Petition 870250090930, dated 06 / 10 / 2025, page 20 / 90 12 / 29

[0043] For illustrative purposes, exemplary principles and embodiments of the present disclosure will be described below with reference to Fig. 1 to Fig. 6. However, it should be noted that these embodiments are given to enable those skilled in the art to understand the inventive concepts of the present disclosure and implement the solution as proposed herein and are not intended to limit the scope of the present application in any way.

[0044] FIG. 1 illustrates an example of a communication network 100 in which some exemplary embodiments of the present disclosure can be implemented. As illustrated in FIG. 1, the communication network 100 includes a terminal device (which may also be referred to as user equipment or UE) 110 and two network devices (which may also be referred to as gNB or BS), such as TRP 120-1 and 120-2 (collectively “120”). Although one terminal device 110 and two network devices 120 are shown in FIG. 1, the numbers of network devices and terminal devices are not limited. In other words, there may be one or more network devices 110 and one or more terminal devices 120 in the network.

[0045] Network devices 120 can provide services to terminal device 110, and network devices 120 and terminal device 110 can communicate data and control information with each other. In some embodiments, network devices 120 and terminal device 110 can communicate with direct links / channels.

[0046] In the 100 communication system, a link from network devices 120 to terminal device 110 is referred to as a downlink (DL), while a link from terminal device 110 to network device 120 is referred to as an uplink (UL). In a downlink, network devices 120 are transmitting (TX) devices (or transmitters) and terminal device 110 is a receiving (RX) device (or receiver). In an uplink, terminal device 110 is a transmitting (TX) device (or transmitter) and network devices 120 are RX devices (or receivers). It should be understood that network devices 120 can provide one or more service cells. As illustrated in Fig. 1, the 120 network devices together provide a 102 service cell, and the 110 terminal device camps in the 102 service cell. In some embodiments, the 120 network device Petition 870250090930, dated 06 / 10 / 2025, p. 21 / 90 13 / 29 can provide multiple service cells and the terminal device 120 can switch from a source cell to a target cell between service cells during its mobility. It should be understood that the number of service cell(s) shown in Fig. 1 is for illustrative purposes only and does not suggest any limitation.

[0047] Communications in the network environment 100 may be implemented in accordance with any suitable communication protocol(s), including, but not limited to, fourth-generation (4G) and fifth-generation (5G) cellular communication protocols and the like, wireless local area network communication protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 and the like, and / or any other protocols currently known or to be developed in the future.Furthermore, communication may utilize any appropriate 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 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 / or any other technologies currently known or to be developed in the future.

[0048] In some embodiments, service cell 102 may comprise a primary cell, a secondary primary cell, or a secondary cell with multiple network devices 120, such as TRPs. As mentioned, terminal device 110 may have two TAGs for service cell 102 and employ different TATs so that one of the network devices is able to provide separate TACs for the TAGs. Terminal device 110 may determine that one of the TAGs is a primary TAG and the other is a secondary TAG. Upon expiring one or more TATs, terminal device 110 may retain one of the primary TAG and one of the secondary TAG. The network device 120 providing the TAC is also aware of the TAT expiration. It knows which TAG is held on terminal device 110, and may act accordingly.

[0049] It should be understood that the number of devices and their connection relationships and types shown in Fig. 1 are for illustrative purposes only and do not suggest any limitations. Petition 870250090930, dated 06 / 10 / 2025, page 22 / 90 14 / 29 The communication system 100 may comprise any suitable number of devices adapted to implement embodiments of the present disclosure.

[0050] FIG. 2 illustrates an example of a process flow according to some exemplary embodiments of the present disclosure. For ease of understanding, process flow 200 will be described in reference to FIG. 1. It should be noted that although process flow 200 has been described in reference to communication network 100 of FIG. 1, this process flow 200 can be equally applied to other similar communication scenarios.

[0051] In block 212, terminal device 110 determines at least two timing advance groups (TAGs) for a service cell. In some embodiments, the service cell may comprise a primary cell, a primary secondary cell, or a secondary cell. In some embodiments, the service cell may be a special cell (SpCell, i.e., PCell or PSCell). The service cell may provide services with multiple network devices 120 (such as TRPs). One of the network devices 120 (hereinafter, network device 120) may be configured to provide control signals to terminal device 110.

[0052] The at least two TAGs can comprise a primary TAG and a secondary TAG. Which is the primary TAG of the cell group / SpCell can be preconfigured, or the TAG with TAT still running can become the primary TAG if only one TAT expires for the SpCell TAGs.

[0053] In some embodiments, the terminal device may determine one of at least two TAGs to be the primary TAG based on a configuration indicating the primary TAG. The terminal device 110 may receive an RRC connection reconfiguration or other control signals from the network device 120 indicating the primary TAG. For example, a TAG with a lower TAG identity (TAG ID) may be specified as the primary TAG. In some examples, the primary TAG is always associated with SpCell (i.e., PCell or PSCell).

[0054] The roles of the primary TAG and secondary TAG can be swapped if the configured primary TAG becomes invalid. In some modes, the terminal device 110 can determine the configured primary TAG as secondary if the TAT Petition 870250090930, dated 06 / 10 / 2025, page 23 / 90 15 / 29 corresponding to expire and the secondary TAG configured as primary if the TAT is still running.

[0055] In block 214, terminal device 110 determines whether at least one time alignment timer (TAT) of the at least two TAGs has expired. TAT expiration means that terminal device 110 is not in synchronization with network device 120, and the corresponding TAG value becomes invalid. In some embodiments, terminal device 110 and network device 120 may be prompted to perform a random access procedure (RACH) for synchronization when a new TAC is transmitted from network device 120 to terminal device 110. However, in some cases, the network device does not explicitly indicate the TAG ID for the new TAC.

[0056] In block 216, terminal device 110 maintains, based on the determination that at least one TAT has expired, one of the primary TAG and one of the secondary TAG. By maintaining a TAG, network device 120 and terminal device 110 can remove ambiguities in the RACH procedure and UL signal transmissions.

[0057] In some embodiments, the 110 terminal device may release a secondary TAG configuration associated with the secondary TAG. The terminal device may release the secondary TAG configuration upon expiration of both TATs associated with SpCell TAGs; upon expiration of the TAT associated with the primary TAG; or upon expiration of the TAT associated with any of the TAGs associated with SpCell, after which the other TAT still running becomes the primary TAG. In some instances, the 110 terminal device may release the secondary TAG configuration only for SpCell (i.e., PCell or PSCell) or for part of the secondary TAG configuration associated with SpCell. In some instances, when the secondary TAG includes service cells other than SpCell (e.g., one or more secondary cells), the 110 terminal device retains the secondary TAG configuration for service cells other than SpCell.

[0058] In some embodiments, the 110 terminal device releases the secondary TAG configuration upon expiration of TATs associated with at least two TAGs. Additionally or alternatively, the 110 terminal device may release the configuration of Petition 870250090930, dated 06 / 10 / 2025, p. 24 / 90 16 / 29 Secondary TAG upon expiration of a TAT associated with the primary TAG. Additionally or alternatively, the terminal device 110 may release the secondary TAG configuration upon expiration of a TAT associated with the primary TAG or upon expiration of a TAT associated with the secondary TAG.

[0059] In some embodiments, the 110 terminal device may release PUCCH resources associated with the secondary TAG. Additionally or alternatively, the 110 terminal device may release polling reference signal (SRS) resources associated with the secondary TAG. Additionally or alternatively, the 110 terminal device may clear configured downlink assignments and configured uplink grants associated with the secondary TAG. Additionally or alternatively, the 110 terminal device may clear PUSCH resources for semi-persistent channel state information (CSI) reporting associated with the secondary TAG.

[0060] In some embodiments, the 110 terminal device may disable each of the spatial relationships for any UL signals (e.g., PUCCH, SRS, PUSCH, etc.) associated with the TAG upon TAT expiration or upon release of the secondary TAG configuration.In some embodiments, if terminal device 110 has no active spatial relationship to a PUCCH resource after the expiration of TATs in SpCell, terminal device 110 considers all TATs as expired.

[0061] Network device 120 has corresponding actions for terminal device 110. In block 222, network device 120 determines at least two TAGs for a service cell. The at least two TAGs comprise a primary TAG and a secondary TAG that correspond to the TAGs on terminal device 110. Network device 120 can transmit control signals to terminal device 110 indicating which TAG is the primary TAG, for example, a TAG with a lower TAG ID. Furthermore, network device 120 is also aware of the expiration of the TATs of the primary and secondary TAGs, and can determine that the secondary TAG becomes a new primary TAG if the TAT of the original primary TAG expires.

[0062] In block 224, network device 120 determines if at least one time alignment timer (TAT) of the at least two TAGs has expired. The Petition 870250090930, dated 06 / 10 / 2025, page 25 / 90 17 / 29 Network device 120 uses TATs to determine if terminal device 110 is in synchronization. If a TAT of the TAGs expires, network device 120 knows that the TA value of the corresponding TAG becomes invalid. In this case, network device 120 will perform a RACH procedure and transmit a new TAC to the terminal device.

[0063] In block 226, network device 120 determines, based on the determination that at least one TAT has expired, that one of the primary TAGs and one of the secondary TAGs should be kept on a terminal device. Thus, network device 120 is aware of the TAT expiration, it knows the behavior of terminal device 110 and can act accordingly.

[0064] In 230, terminal device 110 and network device 230 can perform a RACH procedure, in which a TAC is transmitted in a random access response (RAR) from network device 120 to terminal device 110. The RACH procedure can be triggered by terminal device 110 using a PRACH preamble or by network device 120 using a PDCCH order.

[0065] Subsequently, upon receiving a TAC in RAR, terminal device 110 applies the TAC to the primary TAG regardless of which SSB was selected for random access if the RA procedure is triggered on the terminal device and if none of the TATs are running. Based on determining that the RACH procedure is triggered on terminal device 110 or determining that at least one of the at least two TAGs has expired, terminal device 110 may apply the TAC to the primary TAG.

[0066] In some embodiments, when the PDCCH order for the RACH procedure is triggered for 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 TAG state used to schedule the PDCCH order with the primary TAG. Implicitly, if terminal device 110 is indicated with the second / other TCI state, terminal device 110 may be associated with the TAG ID of the TAG state (if it is different 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 transmit the order. Petition 870250090930, dated 06 / 10 / 2025, p. 26 / 90 18 / 29 PDCCH to RACH or to the TAG ID corresponding to the PCI indicated in the PDCCH order.

[0067] In some embodiments, terminal device 110 may be configured to store the association of the primary TAG and secondary TAG to TAG IDs (from different TCI states) and their respective TA values. In some embodiments, the random access response provided for the RA preamble transmission may include an indication of whether the terminal device can apply the stored values ​​of the primary TAG and secondary TAG association and the TA values. If the network triggers a PDCCH order associated with the TCI state for the secondary TAG and receives in the response a TAC that carries an indication to apply the stored TA value and the associated TAG ID, the terminal device may determine to apply the previous configuration. If the response does not include the information, the terminal device may assume the TAC applied to the TAG ID associated with the TCI status and the TAG ID associated with the primary TAG.

[0068] In 232, the terminal device can perform a UL transmission. In some modes, the UE can use the beam for UL transmissions used for PRACH preamble transmission until a Transmission Configuration Information (TCI) state update is received from the network (e.g., via RRC reconfiguration or MAC CE).

[0069] In view of the above content, it can be observed that only a single TAG is maintained once the terminal device has a single TAT / no TAT running, removing ambiguities in RA procedure / UL signal transmissions. Since the NW is aware of the TAT expiration, it knows the terminal device's behavior and can act accordingly.

[0070] FIG. 3 illustrates a flowchart of an exemplary method 300 implemented in a terminal device according to some other embodiments of the present disclosure. For ease of understanding, method 300 will be described from the perspective of the terminal device 110 with reference to FIG. 1.

[0071] In block 310, terminal device 110 determines at least two TAGs for a service cell, wherein the at least two TAGs comprise a primary TAG and a secondary TAG. Terminal device 110 may determine one of the TAGs as Petition 870250090930, dated 06 / 10 / 2025, page 27 / 90 19 / 29 being the primary TAG based on an indicative configuration of the primary TAG. Additionally or alternatively, based on a determination that a TAT of the primary TAG has expired, the terminal device 110 may determine the secondary TAG with a running TAT as being primary.

[0072] In block 320, terminal device 110 determines if at least one TAT of the at least two TAGs has expired. Terminal device 110 can employ one TAT for each TAG, and detect if the TAT has expired. Upon detection of TAT expiration, terminal device 110 knows that it is out of sync with the corresponding TAG ID. In some embodiments, the service cell may comprise a primary cell, a primary secondary cell, or a secondary cell with multiple TRPs.

[0073] In block 330, terminal device 110 retains, based on the determination that at least one TAT has expired, one of the primary TAG and one of the secondary TAG. In some embodiments, terminal device 110 may release a secondary TAG configuration associated with the secondary TAG. The secondary TAG configuration may be released upon expiration of TATs associated with at least two TAGs. Additionally or alternatively, the secondary TAG configuration may be released upon expiration of a TAT associated with the primary TAG or a TAT associated with the secondary TAG.

[0074] In some embodiments, the 110 terminal device may release uplink control physical channel resources (PUCCH) associated with the secondary TAG. Additionally or alternatively, the 110 terminal device may release polling reference signal (SRS) resources associated with the secondary TAG. Additionally or alternatively, the 110 terminal device may clear configured downlink assignments and configured uplink grants associated with the secondary TAG. Additionally or alternatively, the 110 terminal device may clear uplink shared physical channel resources (PUSCH) for semi-persistent channel state information (CSI) reporting associated with the secondary TAG.

[0075] In some modes, terminal device 110 can disable a relationship. Petition 870250090930, dated 06 / 10 / 2025, p. 28 / 90 20 / 29 spatial for an uplink (UL) signal associated with the secondary TAG. Thus, the spatial relationship associated with the secondary TAG is suspended.

[0076] In some embodiments, terminal device 110 may receive a timing advance (TAC) command in a random access response (RAR) from a random access channel procedure (RACH). Based on determination that the RACH procedure is triggered on the terminal device or on determination that at least one TAT of at least two TAGs has timed out, terminal device 110 may apply the TAC to the primary TAG.

[0077] In some embodiments, the terminal device 110 may apply a beam for UL transmission used for random access physical channel preamble (PRACH) transmission until reception of a transmission configuration indicator (TCI) status update, where the UL transmission has a timing advance indicated in the TAC.

[0078] In some embodiments, terminal device 110 may store a first TAG ID and a first TA value in association with the primary TAG and store a second TAG ID and a second TA value in association with the secondary TAG. In some embodiments, one or more of the first TAG ID and the second TAG ID may be associated with a PDCCH order for a RACH procedure triggered to terminal device 110. Additionally or alternatively, one or more of the first TAG ID and the second TAG ID may be associated with a PCI indicated in the PDCCH order. Additionally or alternatively, one or more of the first TAG ID and the second TAG ID may be associated with a TCI state used to transmit the PDCCH order.

[0079] In some embodiments, terminal device 110 may receive a RAR provided for a PDCCH order preamble transmission. Terminal device 110 may apply, 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 TA.

[0080] In some embodiments, terminal device 110 may apply the second TA value associated with the secondary TAG based on a determination that the RAR includes an indication for the secondary TAG. Terminal device 110 may apply the Petition 870250090930, dated 06 / 10 / 2025, p. 29 / 90 21 / 29 first TA value associated with the primary TAG based on the determination that the RAR does not include the indication for the secondary TAG.

[0081] FIG. 4 illustrates another flowchart of an exemplary method implemented on a network device according to some embodiments of the present disclosure. For ease of understanding, method 400 will be described from the perspective of terminal device 120 with reference to FIG. 1.

[0082] In block 410, network device 120 determines at least two TAGs for a service cell, wherein the at least two TAGs comprise a primary TAG and a secondary TAG. In block 420, network device 120 determines whether at least one TAT of the at least two TAGs has expired. In block 430, network device 120 determines, based on the determination that at least one TAT has expired, that one of the primary TAG and one of the secondary TAGs is maintained on a terminal device. In some embodiments, the service cell may comprise a primary cell, a primary secondary cell, or a secondary cell with multiple TRPs.

[0083] In some embodiments, the 120 network device may store a first TAG ID and a first TA value in association with the primary TAG and store a second TAG ID and a second TA value in association with the secondary TAG.

[0084] In some embodiments, one or more of the first TAG ID and the second TAG ID may be associated with a PDCCH order for a RACH procedure triggered for terminal device 110. Additionally or alternatively, one or more of the first TAG ID and the second TAG ID may be associated with a PCI indicated in the PDCCH order. Additionally or alternatively, one or more of the first TAG ID and the second TAG ID may be associated with a TCI state used to transmit the PDCCH order.

[0085] In some embodiments, the 120 network device may transmit a provided RAR for a PDCCH order preamble transmission to the terminal device. The RAR may include an indication of whether the primary TAG or the secondary TAG should be applied to the terminal device.

[0086] In some modalities, a device capable of performing method 300 (by Petition 870250090930, dated 06 / 10 / 2025, page 30 / 90 22 / 29 For example, the terminal device 110) may comprise means for carrying out the respective steps of method 300. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit assembly or software module.

[0087] In some exemplary embodiments, the apparatus comprises: means for determining at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on determination that at least one TAT has expired, one of the primary TAG and one of the secondary TAG.

[0088] In some embodiments, the device may comprise means for determining the primary TAG of at least two TAGs based on at least one of the following: a setting indicative of the primary TAG; or, based on determination that a TAT of the primary TAG has expired, determining the secondary TAG with a running TAT as being primary.

[0089] In some embodiments, the device may include means to release a secondary TAG configuration associated with the secondary TAG.

[0090] In some embodiments, means to release a secondary TAG configuration may comprise means to release a secondary TAG based on at least one of the following: expiration of TATs associated with at least two TAGs; expiration of a TAT associated with the primary TAG; or expiration of a TAT associated with the secondary TAG.

[0091] In some embodiments, means to release a secondary TAG configuration may comprise means to release uplink control physical channel resources (PUCCH) associated with the secondary TAG; means to release polling reference signal (SRS) resources associated with the secondary TAG; means to clear configured downlink assignments and configured uplink grants associated with the secondary TAG; and means to clear uplink shared physical channel resources (PUSCH) for transmission. Petition 870250090930, dated 06 / 10 / 2025, page 31 / 90 23 / 29 semi-persistent channel state information (CSI) reports associated with the secondary TAG.

[0092] In some embodiments, the device may comprise means for disabling a spatial relationship to an uplink (UL) signal associated with the secondary TAG.

[0093] In some embodiments, the apparatus may comprise means for receiving a timing advance command (TAC) in a random access response (RAR) of a random access channel procedure (RACH); and means for applying, based on determination that the RACH procedure is triggered on the terminal device or determination that at least one TAT of at least two TAGs has expired, the TAC to the primary TAG.

[0094] In some embodiments, the apparatus may comprise means for applying a beam for UL transmission used for random access physical channel preamble (PRACH) transmission until reception of a transmission configuration indicator (TCI) status update, wherein the UL transmission has a timing advance indicated in the TAC.

[0095] In some embodiments, the device may comprise means for storing a first TAG ID and a first TA value in association with the primary TAG and means for storing a second TAG ID and a second TA value in association with the secondary TAG.

[0096] In some embodiments, at least one of the first TAG ID and the second TAG ID is associated with at least one of: a downlink control physical channel order (PDCCH) for a RACH procedure triggered to the terminal device; a physical cell identity (PCI) indicated in the PDCCH order; or a transmission configuration indicator (TCI) used to transmit the PDCCH order.

[0097] In some embodiments, the apparatus may comprise means for receiving a RAR provided for a PDCCH order preamble transmission and means for applying, 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. Petition 870250090930, dated 06 / 10 / 2025, p. 32 / 90 24 / 29

[0098] In some embodiments, the device may comprise: means for applying, based on a determination that the RAR includes an indication for the secondary TAG, the second TA value associated with the secondary TAG, and means for applying, based on a determination that the RAR does not include the indication for the secondary TAG, the first TA value associated with the primary TAG.

[0099] In some embodiments, the service cell comprises a primary cell, a primary secondary cell, or a secondary cell with multiple transmission and reception points (TRPs).

[00100] In some embodiments, the apparatus additionally comprises means for carrying out other steps in some embodiments of method 300. In some embodiments, the means comprise at least one processor and at least one memory that includes computer program code, at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform.

[00101] In some embodiments, a device capable of performing method 400 (for example, network device 120) may comprise means for performing the respective steps of method 400. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit assembly or software module.

[00102] In some embodiments, the apparatus may comprise: means for determining at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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 determination that at least one TAT has expired, that one of the primary TAG and one of the secondary TAG is maintained in a terminal device.

[00103] In some embodiments, the device may comprise means for determining the primary TAG based on at least one of the following: a setting indicative of the primary TAG; or, based on determination that a TAT of the primary TAG has expired, determining the secondary TAG with a running TAT as being primary. Petition 870250090930, dated 06 / 10 / 2025, page 33 / 90 25 / 29

[00104] In some embodiments, the device may comprise means for storing a first TAG ID and a first TA value in association with the primary TAG and means for storing a second TAG ID and a second TA value in association with the secondary TAG.

[00105] In some embodiments, at least one of the first TAG ID and the second TAG ID is associated with at least one of: a downlink control physical channel order (PDCCH) for a RACH procedure triggered to the terminal device; a physical cell identity (PCI) indicated in the PDCCH order; or a transmission configuration indicator (TCI) used to transmit the PDCCH order.

[00106] In some embodiments, the apparatus may comprise means for transmitting a provided RAR for a PDCCH order preamble transmission to the terminal device, wherein the RAR includes an indication of whether the primary TAG or the secondary TAG should be applied to the terminal device.

[00107] In some embodiments, the service cell comprises a primary cell, a primary secondary cell, or a secondary cell with multiple transmission and reception points (TRPs).

[00108] In some embodiments, the apparatus additionally comprises means for carrying out other steps in some embodiments of method 400. In some embodiments, the means comprise at least one processor and at least one memory that includes computer program code, at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform.

[00109] FIG. 5 illustrates a simplified block diagram of a device 500 that is suitable for implementing some exemplary embodiments of the present disclosure. The device 500 can be provided to implement a communication device, for example, a network device 120 or a terminal device 110 as shown in FIG. 1. As shown, the device 500 includes one or more processors 510, one or more memories 520 coupled to the processor 510 and one or more communication modules 540 coupled to the processor 510. Petition 870250090930, dated 06 / 10 / 2025, p. 34 / 90 26 / 29

[00110] The 540 communication module is for bidirectional communication. The 540 communication module has at least one antenna to facilitate communication. The communication interface can represent any interface that is necessary for communication with other network elements.

[00111] The 510 processor can be of any type suitable for the local technical network and may include one or more of the following: general-purpose computers, special-purpose computers, microprocessors, digital signal processors (DSPs), and processors based on multi-core processor architecture, as non-limiting examples. The 500 device may have multiple processors, such as an application-specific integrated circuit chip that is time-dependent on a clock that synchronizes with the main processor.

[00112] 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, a Read-Only Memory (ROM) 524, an electrically programmable read-only memory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disc (DVD), and other magnetic and / or optical storage. Examples of volatile memories include, but are not limited to, a random access memory (RAM) 522 and other volatile memories that will not last through the power-off period.

[00113] A computer program 530 includes computer executable instructions that are executed by the associated processor 510. The program 530 can be stored in ROM 524. The processor 510 can perform any appropriate actions and processing by loading the program 530 into RAM 522.

[00114] The embodiments of the present disclosure can be implemented by means of program 530 so that device 500 can perform any process of the disclosure as discussed in reference to FIGS. 3 and 4. The embodiments of the present disclosure can also be implemented by hardware or by a combination of software and hardware.

[00115] In some embodiments, the 530 program may be tangibly contained in a computer-readable medium that may be included in the 500 device (as in Petition 870250090930, dated 06 / 10 / 2025, page 35 / 90 27 / 29 memory 520) or on other storage devices that are accessible by device 500. Device 500 can load program 530 from the computer-readable medium into RAM 522 for execution. The computer-readable medium can include any type of tangible non-volatile storage, such as ROM, EPROM, flash memory, a hard disk, CD, DVD, and the like.

[00116] FIG. 6 illustrates a block diagram of an example of a computer-readable medium 600 according to some exemplary embodiments of the present disclosure. The computer-readable medium 600 has the program 530 stored thereon. Note that although the computer-readable medium 600 is shown in the form of a CD or DVD in FIG. 5, the computer-readable medium 600 may be in any other form suitable for carrying or containing the program 530.

[00117] In general, various embodiments of the present disclosure may be implemented in hardware or special-purpose circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that can be executed by a controller, microprocessor, or other computing device. Although various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other graphical representations, it should be understood that the block, apparatus, system, technique, or method described herein may be implemented, as non-limiting examples, in hardware, software, firmware, special-purpose or logic circuits, general-purpose hardware or controller or other computing devices, or some combination thereof.

[00118] The present disclosure also provides at least one computer program product tangibly stored on a non-transient, computer-readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, that are executed on a device on a target real or virtual processor, to perform method 300 or 400 as described above with reference to FIG. 3 or FIG. 4. In general, program modules include routines, programs, libraries, objects, classes, Petition 870250090930, dated 06 / 10 / 2025, page 36 / 90 28 / 29 components, data structures, or similar elements that perform particular tasks or implement particular abstract data types. The functionality of program modules can be combined or divided among program modules as desired in various ways. Machine-executable instructions for program modules can be executed within a local or distributed device. In a distributed device, program modules can be located in both local and remote storage media.

[00119] Program code for executing methods of the present disclosure may be written in any combination of one or more programming languages. Such program codes may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that the program codes, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed wholly on one machine, partially on the machine as a stand-alone software package, partially on the machine and partially on a remote machine, or wholly on the remote machine or server.

[00120] In the context of the present disclosure, computer program codes or related data may be carried by any suitable carrier to enable the device, apparatus, or processor to perform various processes and operations as described above. Examples of carriers include a signal, computer-readable media, and the like.

[00121] A computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. A computer-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More specific examples of computer-readable storage media would include an electrical connection having one or more wires, a laptop computer floppy disk, a hard disk drive, random access memory (RAM), read-only memory (ROM), read-only memory. Petition 870250090930, dated 06 / 10 / 2025, page 37 / 90 29 / 29 erasable programmable memory (EPROM or Flash memory), an optical fiber, a portable compact disc (CD-ROM) read-only memory, an optical storage device, a magnetic storage device, or any suitable combination thereof. The term “non-transient,” as used herein, refers to a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation in data storage persistence (e.g., RAM versus ROM).

[00122] Additionally, although the operations are represented in a particular order, this should not be understood to require that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are contained in the discussions above, these should not be interpreted as limitations on the scope of the present disclosure, but rather as descriptions of attributes that may be specific to particular modalities. Certain attributes that are described in the context of separate modalities may also be implemented in combination in a single modality.On the other hand, several attributes that are described in the context of a single modality can also be implemented in multiple modalities separately or in any suitable subcombination.

[00123] Although the present disclosure has been described in languages ​​specific to structural attributes and / or methodological acts, it should be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific attributes or acts described above. Instead, the specific attributes and acts described above are disclosed as exemplary forms of implementation of claims. Petition 870250090930, dated 06 / 10 / 2025, p. 38 / 90

Claims

1 / 7 CLAIMS 1. A terminal device characterized by comprising: at least one processor; and at least one memory that stores instructions which, when executed by the at least one processor, cause the terminal device to at least: determine at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on determination that at least one TAT has expired, one of the primary TAG and one of the secondary TAG.

2. Terminal device, according to claim 1, wherein the terminal device is characterized by being further caused to determine the primary TAG of at least two TAGs based on at least one of the following: a configuration indicative of the primary TAG; or based on determination that a TAT of the primary TAG has expired, determine the secondary TAG with a running TAT as being primary.

3. Terminal device according to claim 1 or 2, wherein the terminal device is characterized by being additionally caused to: release a secondary TAG configuration associated with the secondary TAG.

4. Terminal device according to claim 3, wherein the terminal device is characterized in that it is additionally caused to release the secondary TAG configuration based on at least one of the following: expiration of TATs associated with at least two TAGs; expiration of a TAT associated with the primary TAG; or expiration of a TAT associated with the secondary TAG.

5. Terminal device, according to claims 3 or 4, wherein the terminal device is characterized by being further caused to release the configuration of Petition 870250090930, dated 06 / 10 / 2025, page 39 / 90 2 / 7 Secondary TAG by at least one of the following: releasing uplink control physical channel resources (PUCCH) associated with the secondary TAG; releasing polling reference signal (SRS) resources associated with the secondary TAG; clearing configured downlink assignments and configured uplink grants associated with the secondary TAG; or clearing uplink shared physical channel resources (PUSCH) for semi-persistent channel state information (CSI) reporting associated with the secondary TAG.

6. Terminal device, according to any one of claims 1 to 5, wherein the terminal device is characterized by being further caused to: disable a spatial relationship for an uplink signal (UL) associated with the secondary TAG.

7. Terminal device, according to any one of claims 1 to 6, wherein the terminal device is characterized in that it is further caused to: receive a timing advance command (TAC) in a random access response (RAR) of a random access channel procedure (RACH); and based on determination that the RACH procedure is triggered on the terminal device or determination that at least one TAT of at least two TAGs has expired, apply the TAC to the primary TAG.

8. Terminal device according to claim 7, wherein the terminal device is characterized by being further caused to: apply a beam for UL transmission used for random access physical channel preamble (PRACH) transmission until reception of a transmission configuration indicator (TCI) status update, wherein the UL transmission has a timing advance indicated in the TAC.

9. Terminal device, according to any one of claims 1 to 8, wherein the terminal device is characterized by being further caused to: store a first TAG ID and a first timing advance (TA) value in association with the primary TAG; and store a second TAG ID and a second TA value in association with the secondary TAG.

10. Terminal device according to claim 9, characterized in that at least one of the first TAG ID and the second TAG ID is associated with at least one of: a downlink control physical channel order (PDCCH) for a RACH procedure triggered for the terminal device; a physical cell identity (PCI) indicated in the PDCCH order; or a transmission configuration indicator (TCI) used to transmit the PDCCH order.

11. Terminal device according to claim 10, wherein the terminal device is characterized in that it is further caused to: receive a RAR provided for a PDCCH order preamble transmission; and apply, 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.

12. Terminal device according to claim 11, wherein the terminal device is characterized by being further caused to: based on a determination that the RAR includes an indication for the secondary TAG, apply the second TA value associated with the secondary TAG, and based on a determination that the RAR does not include the indication for the secondary TAG, apply the first TA value associated with the primary TAG.

13. Terminal device, according to any one of claims 1 to 12, characterized in that the service cell comprises a primary cell, a primary secondary cell, or a secondary cell with multiple transmission and reception points (TRPs).

14. Network device characterized by comprising: at least one processor; and at least one memory that stores instructions that, when executed by Petition 870250090930, dated 06 / 10 / 2025, page 41 / 90 4 / 7, at least one processor, causes the network device to at least: determine at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on determination that at least one TAT has expired, that one of the primary TAG and one of the secondary TAG is maintained in a terminal device.

15. Network device according to claim 14, wherein the network device is characterized by being further caused to determine the primary TAG based on at least one of the following: a configuration indicative of the primary TAG; or based on a determination that a TAT of the primary TAG has expired, determine the secondary TAG with a running TAT as being primary.

16. Network device according to any one of claims 14 to 15, wherein the network device is characterized by being further caused to: store a first TAG ID and a first timing advance (TA) value in association with the primary TAG; and store a second TAG ID and a second TA value in association with the secondary TAG.

17. Network device according to claim 16, characterized in that at least one of the first TAG ID and the second TAG ID is associated with: a downlink control physical channel order (PDCCH) for a RACH procedure triggered on the network device; a physical cell identity (PCI) indicated in the PDCCH order, or a transmission configuration indicator (TCI) used to transmit the PDCCH order.

18. Network device according to claim 17, wherein the network device is characterized by being further caused to: transmit a RAR provided for a PDCCH order preamble transmission to the terminal device, wherein the RAR includes an indication of whether the primary TAG or the secondary TAG should be applied to the terminal device.

19. Network device, according to any one of claims 14 to 18, characterized in that the service cell comprises a primary cell, a primary secondary cell, or a secondary cell with multiple transmit and receive points (TRPs).

20. A method characterized by comprising: determining at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on the determination that at least one TAT has expired, one of the primary TAG and one of the secondary TAG.

21. A method characterized by comprising: determining at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, that one of the primary TAG and one of the secondary TAG is maintained in a terminal device.

22. Apparatus characterized by comprising: means for determining at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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 Petition 870250090930, dated 06 / 10 / 2025, page 43 / 90 6 / 7 means for maintaining, based on determination that at least one TAT has expired, one of the primary TAG and one of the secondary TAG.

23. Apparatus characterized by comprising: means for determining at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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 determination that at least one TAT has expired, that one of the primary TAG and one of the secondary TAG is maintained in a terminal device.

24. Non-transient computer-readable medium characterized by comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least: determine at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on determination that at least one TAT has expired, one of the primary TAG and one of the secondary TAG.

25. Non-transient computer-readable medium characterized by comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least: determine at least two timing advance groups (TAGs) for a service cell, wherein the at least two TAGs comprise 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, based on determination that at least one TAT has expired, that one of the primary TAG and one of the secondary TAGs is maintained in a terminal device.

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