Method for LTM mechanism design

Abstract

Methods, devices, and systems are provided for providing advance timing advance (TA) acquisition. A radio resource control (RRC) configuration acquired in advance TA is received from a base station. A PDCCH command for triggering a random access channel (RACH) procedure towards a candidate cell is received from a base station. The RACH procedure for the advance TA acquisition is initiated based on the received RRC configuration and the PDCCH command. The preamble is transmitted on the candidate cell to the base station at the calculated transmission power.

Description

Technical Field

[0001] This topic generally relates to wireless communications. In particular, it relates to methods, apparatus, and systems for implementing the Random Access Channel (RACH) procedure toward L1 / L2 Triggered Mobility (LTM) candidate cells, how a user equipment (UE) should handle uplink (UL) grants (i.e., dynamic grant (DG) / configuration grant (CG)) for transmitting dedicated control channel (DCCH) messages, and how the UE should maintain a timing lead (TA) value during LTM. Background Technology

[0002] Previous efforts in LTM (i.e., L1 / L2 triggered mobility) to obtain UL synchronization before performing cell handover involved introducing an early RACH procedure to reduce handover delay. The early RACH procedure may exclude the Random Access Response (RAR) step. That is, only the preamble transmission step (without any feedback signaling) can be used to determine whether the RACH was successful. This approach differs from current RACH procedures. According to the content of this topic, the characteristics of a one-step RACH procedure will be described.

[0003] During LTM, the TA (Targeting Aspect) for candidate cells prior to cell handover can be maintained. However, in conventional implementations, the TA is considered invalid during LTM. This document describes how the UE can maintain its TA value during LTM.

[0004] RACH-free LTM can be supported for both inter-DU LTM and intra-DU LTE. Furthermore, both Configuration Grant (CG) and Dynamic Grant (DG) can be used to transmit DCCH messages (i.e., RRCReconfigurationComplete) to notify the target cell of UE arrival. This topic will describe how a UE can utilize CG and / or DG to transmit DCCH messages, and the associated advantages. Summary of the Invention

[0005] This topic relates to a method, apparatus, and system for implementing a random access channel (RACH) procedure toward L1 / L2 triggered mobility (LTM) candidate cells, how a user equipment (UE) should handle uplink (UL) grants (i.e., dynamic grant (DG) / configuration grant (CG)) for transmitting dedicated control channel (DCCH) messages, and how the UE should maintain a timing lead (TA) value during LTM.

[0006] In some embodiments, a method for providing advance time advance (TA) acquisition includes: receiving a radio resource control (RRC) configuration for TA acquisition from a base station; receiving a PDCCH command from the base station to trigger a random access channel (RACH) toward a candidate cell; initiating an RACH procedure for TA acquisition based on the received RRC configuration and PDCCH command; and transmitting a preamble to the base station on the candidate cell at a calculated transmission power.

[0007] In some embodiments, a method for providing advance time advance (TA) acquisition in a user equipment (UE) includes: receiving an L1 / L2 triggered mobility (LTM) cell handover MAC CE from a source cell; determining a TA value to be maintained during LTM and performing a corresponding operation; and transmitting the maintained TA value to a target cell.

[0008] In some embodiments, a method for providing uplink (UL) granting of a dedicated control channel (DCCH) message includes: receiving a radio resource control (RRC) configuration for L1 / L2 triggered mobility (LTM) from a source cell; receiving an LTM cell handover command (MAC CE) from the source cell; applying the RRC configuration of an LTM candidate cell indicated by the LTM cell handover command (MAC CE); generating a DCCH message in response to the RRC configuration of the LTM candidate cell; transmitting an initial transmission to a target cell; and determining that LTM was successfully completed.

[0009] In some other embodiments, an apparatus for wireless communication may include: a memory storing instructions, and processing circuitry communicating with the memory. When the processing circuitry executes the instructions, the processing circuitry is configured to perform the methods described above.

[0010] In some other embodiments, a device for wireless communication may include: a memory storing instructions, and processing circuitry communicating with the memory. When the processing circuitry executes the instructions, the processing circuitry is configured to perform the methods described above.

[0011] In some other embodiments, a computer-readable medium includes instructions that, when executed by a computer, cause the computer to perform the methods described above.

[0012] The above and other aspects, and their embodiments, are described in more detail in the accompanying drawings, description, and claims. Attached Figure Description

[0013] Figure 1 An example wireless communication system including a wireless base station / gNB 200 and a user equipment (UE) 300 is shown.

[0014] Figure 2An example of a base station / gNB 200 is shown.

[0015] Figure 3 An example of UE 300 is shown.

[0016] Figure 4 The procedure for advance TA acquisition (e.g., RACH procedure) between UE 300 and gNB 200 is shown.

[0017] Figure 5 The TA management process between UE 300, source cell 501 and target cell 502 is shown.

[0018] Figure 6 The UL authorization process for DCCH messages between UE 300, source cell 501, and target cell 502 is illustrated. Detailed Implementation

[0019] This subject matter will now be described in detail below with reference to the accompanying drawings, which form part of this subject matter and illustrate specific examples of embodiments by way of illustration. However, it should be noted that this subject matter can be embodied in many different forms, and therefore, the subject matter covered or claimed is intended to be construed as not being limited to any of the embodiments set forth below.

[0020] Throughout this specification and claims, terms may have nuanced meanings implied or suggested in the context, beyond their explicitly stated meanings. Similarly, the phrases “in one embodiment” or “in some embodiments” as used herein do not necessarily refer to the same embodiment, and the phrases “in another embodiment” or “in other embodiments” as used herein do not necessarily refer to different embodiments. For example, the claimed subject matter is intended to encompass, in whole or in part, combinations of exemplary embodiments or implementations.

[0021] Generally, terms can be understood, at least in part, from their usage in context. For example, terms such as “and,” “or,” or “and / or” as used herein can include a variety of meanings, which can depend, at least in part, on the context in which such terms are used. Typically, if “or” is used to relate a list, such as A, B, or C, it is intended to mean A, B, and C, used here in an inclusive sense, and A, B, or C, used here in an exclusive sense. Furthermore, depending at least in part on the context, the terms “one or more” or “at least one” as used herein can be used to describe any feature, structure, or characteristic in a singular sense or a combination of features, structures, or characteristics in a plural sense. Similarly, terms such as “a,” “an,” or “the” can also be understood, at least in part on the context, to express either a singular or a plural usage. Moreover, the term “based on” can be understood not necessarily to express an exclusive set of factors, but again can, at least in part on the context, allow for additional factors that are not necessarily explicitly described.

[0022] Figure 1 A schematic diagram of an example wireless communication system 100 is shown, which includes a plurality of communication nodes (or simply nodes) configured to communicate wirelessly with each other. Generally, the communication nodes include at least one user equipment 102 and at least one wireless access node 104. Figure 1 The example wireless communication system 100 is shown as including two user equipments 102 (including a first user equipment 102 (1) and a second user equipment 102 (2)) and a wireless access node 104. However, various other examples of wireless communication systems 100 including any combination of one or more user equipments 102 and / or one or more wireless access nodes 104 are also possible.

[0023] Generally, user equipment as described herein (such as user equipment 102) may include a single electronic device or apparatus, or multiple electronic devices or apparatuses (e.g., a network) capable of wireless communication over a network. User equipment may include or be otherwise referred to as a user terminal, user terminal equipment, or user equipment (UE). Furthermore, user equipment can be, or is not limited to, mobile devices (such as mobile phones, smartphones, smartwatches, tablets, laptops, vehicles or other means of transportation (human-powered, motor- or engine-driven, such as cars, airplanes, trains, ships or bicycles as non-limiting examples) or fixed or stationary devices (such as desktop computers or other computing devices that are typically stationary for extended periods, such as home appliances, other relatively heavy devices including the Internet of Things (IoT), or computing devices used in commercial or industrial environments). In various embodiments, user equipment 102 may include transceiver circuitry 106 coupled to antenna 108 to enable wireless communication with wireless access node 104. Transceiver circuitry 106 may also be coupled to processor 110, which may also be coupled to memory 112 or other storage devices. Memory 112 may store instructions or code therein that, when read and executed by processor 110, cause processor 110 to perform the various methods described herein.

[0024] Furthermore, in general, a wireless access node as described herein (such as wireless access node 104) may include a single electronic device or apparatus, or multiple electronic devices or apparatuses (e.g., a network), and may include one or more base stations or other wireless network access points capable of wirelessly communicating with one or more user equipments and / or one or more other wireless access nodes 104 via a network. For example, in various embodiments, wireless access node 104 may include a 4G LTE base station, a 5G NR base station, a 5G central unit base station, a 5G distributed unit base station, a next-generation Node B (gNB), an enhanced Node B (eNB), or other similar or next-generation (e.g., 6G) base station. Wireless access node 104 may include transceiver circuitry 114 coupled to an antenna 116 (which may include an antenna tower 118 in various methods) to enable wireless communication with user equipment 102 or another wireless access node 104. Transceiver circuitry 114 may also be coupled to one or more processors 120, which may also be coupled to memory 122 or other storage devices. The memory 122 may store instructions or code therein that, when read and executed by the processor 120, cause the processor 120 to perform one or more methods described herein.

[0025] In various embodiments, two communication nodes in the wireless communication system 100—such as user equipment 102 and wireless access node 104, two user equipment 102 without wireless access node 104, or two wireless access nodes 104 without user equipment 102—can be configured to wirelessly communicate with each other in or through a mobile network and / or wireless access network according to one or more standards and / or specifications. Generally, standards and / or specifications can define rules or procedures under which wireless nodes can wirelessly communicate, and in various embodiments, these rules or procedures can include those for communication in the millimeter (mm) wave band and / or utilizing multi-antenna schemes and beamforming capabilities. Additionally or alternatively, standards and / or specifications are those that define radio access technologies and / or cellular technologies, such as fourth-generation (4G) Long Term Evolution (LTE), fifth-generation (5G) New Radio (NR), or New Radio Unlicensed (NR-U) as non-limiting examples.

[0026] Furthermore, in the wireless communication system 100, communication nodes are configured to wirelessly transmit signals to each other. Generally, communication between two communication nodes in the wireless communication system 100 can be or includes transmission or reception, and is usually both simultaneous, depending on the perspective of the specific node in the communication. For example, for a given communication between a first node and a second node, where the first node is transmitting a signal to the second node and the second node is receiving a signal from the first node, the first node can be referred to as a source or transmitting node or device, and the second node can be referred to as a destination or receiving node or device, and the communication can be considered as transmission from the perspective of the first node and as reception from the perspective of the second node. Of course, since communication nodes in the wireless communication system 100 can both transmit and receive signals, a single communication node can be both a transmitting / source node and a receiving / destination node simultaneously, or switch between a source / transmitting node and a destination / receiving node.

[0027] Furthermore, specific signals can be characterized or defined as uplink (UL) signals, downlink (DL) signals, or sidelink (SL) signals. Uplink signals are signals transmitted from user equipment 102 to radio access node 104. Downlink signals are signals transmitted from radio access node 104 to user equipment 102. Sidelink signals are signals transmitted from one user equipment 102 to another user equipment 102, or from one radio access node 104 to another radio access node 104. Additionally, for sidelink transmission, the first / source user equipment 102 directly transmits the sidelink signal to the second / destination user equipment 102 without forwarding it to radio access node 104.

[0028] Furthermore, the signals transmitted between communication nodes in the wireless communication system 100 can be characterized or defined as data signals or control signals. Generally, data signals are signals that include or carry data, such as multimedia data (e.g., voice and / or image data), and control signals are signals that carry control information that configures the communication nodes to communicate with each other in a certain way, or otherwise controls how the communication nodes transmit data signals to each other. Additionally, certain signals can be defined or characterized by combinations of data / control and uplink / downlink / sidelink signals (including uplink control signals, uplink data signals, downlink control signals, downlink data signals, sidelink control signals, and sidelink data signals).

[0029] For at least some specifications, such as 5G NR, data signals and control signals are transmitted and / or carried on physical channels. Generally, a physical channel corresponds to a set of time-frequency resources used for transmitting signals. Different types of physical channels can be used to transmit different types of signals. For example, physical data channels (or simply data channels) are used to transmit data signals, and physical control channels (or simply control channels) are used to transmit control signals. Example types of physical data channels include, but are not limited to: Physical Downlink Shared Channel (PDSCH) for transmitting downlink data signals, Physical Uplink Shared Channel (PUSCH) for transmitting uplink data signals, and Physical Sidelink Shared Channel (PSSCH) for transmitting sidelink data signals. Furthermore, example types of physical control channels include, but are not limited to: Physical Downlink Control Channel (PDCCH) for transmitting downlink control signals, Physical Uplink Control Channel (PUCCH) for transmitting uplink control signals, and Physical Sidelink Control Channel (PSCCH) for transmitting sidelink control signals. As used herein, for simplicity, unless otherwise stated, a specific type of physical channel is also used to refer to the signal transmitted on that specific type of physical channel, and / or the transmission on that specific type of transmission. For example, PDSCH refers to the Physical Downlink Shared Channel itself, downlink data signals transmitted on the PDSCH, or downlink data transmission. Therefore, a communication node transmitting or receiving a PDSCH means that the communication node is transmitting or receiving signals on the PDSCH.

[0030] Furthermore, for at least some specifications (such as 5G NR) and / or for at least some types of control signals, the control signals transmitted by the communication nodes may include control information that includes information necessary to enable the transmission of one or more data signals between the communication nodes and / or to schedule one or more data channels (or one or more transmissions on a data channel). For example, such control information may include information necessary for the proper reception, decoding, and demodulation of data signals received on a physical data channel during data transmission, and / or for informing user equipment of uplink scheduling authorization regarding the resources and transmission formats to be used for uplink data transmission. In some embodiments, the control information includes downlink control information (DCI) transmitted in the downlink direction from radio access node 104 to user equipment 102. In other embodiments, the control information includes uplink control information (UCI) transmitted in the uplink direction from user equipment 102 to radio access node 104, or sidelink control information (SCI) transmitted in the sidelink direction from one user equipment 102 (1) to another user equipment 102 (2).

[0031] Furthermore, in the wireless communication system 100, the time slot format for multiple time slots or frames can be configured by the wireless access node 104 or specified by a protocol. In some examples, time slots can be indicated or specified as downlink time slots, flexible time slots, or uplink time slots. Additionally, in various embodiments, orthogonal frequency divisional multiplexing (OFDM) symbols can be indicated or specified as downlink symbols, flexible symbols, or uplink symbols.

[0032] Figure 2 An example of base station 200 is shown. Example base station 200 may include radio transmit / receive (Tx / Rx) circuitry 208 for transmitting / receiving communications with a UE and / or other base stations. Base station 200 may also include network interface circuitry 209 for communicating with other base stations and / or the core network, such as optical or wired interconnects, Ethernet, and / or other data transmission media / protocols. Base station 200 may optionally include input / output (I / O) interfaces 206 for communicating with an operator or similar personnel.

[0033] Base station 200 may also include system circuitry 204. System circuitry 204 may include one or more processors 221 and / or memory 222. Memory 222 may include operating system 224, instructions 226, and parameters 228. Instructions 226 may be configured for one or more processors 221 to perform base station functions. Parameters 228 may include parameters for supporting the execution of instructions 226. For example, parameters may include network protocol settings, bandwidth parameters, radio frequency mapping allocation, and / or other parameters.

[0034] Figure 3An example of an electronic device for implementing terminal device 300 (e.g., user equipment (UE)) is shown. UE 300 may be a mobile device, such as a smartphone or a mobile communication module located in a vehicle. UE 300 may include a communication interface 302, system circuitry 304, input / output interface (I / O) 306, display circuitry 308, and storage device 309. The display circuitry may include a user interface 310. System circuitry 304 may include any combination of hardware, software, firmware, or other logic / circuit. System circuitry 304 may be implemented, for example, using one or more system-on-chip (SoC), application-specific integrated circuit (ASIC), discrete analog and digital circuitry, and other circuitry. System circuitry 304 may be part of an implementation of any desired functionality in UE 300. In this regard, system circuitry 304 may include, as an example, the following logic: facilitating the decoding and playback of music and video, such as MP3, MP4, MPEG, AVI, FLAC, AC3, or WAV decoding and playback; running applications; accepting user input; saving and retrieving application data; establishing, maintaining, and terminating cellular phone calls or data connections, as an example, for internet connections; establishing, maintaining, and terminating wireless network connections, Bluetooth connections, or other connections; and displaying relevant information on user interface 310. User interface 310 and input / output (I / O) interface 306 may include a graphical user interface, touch-sensitive display, haptic feedback or other haptic output, voice or facial recognition input, buttons, switches, speakers, and other user interface elements. Other examples of I / O interface 306 may include microphones, video and still image cameras, temperature sensors, vibration sensors, rotation and orientation sensors, headset and microphone input / output jacks, Universal Serial Bus (USB) connectors, memory card slots, radiation sensors (e.g., IR sensors), and other types of input.

[0035] Communication interface 302 may include radio frequency (RF) transmit (Tx) and receive (Rx) circuitry 316, which handles the transmission and reception of signals via one or more antennas 314. Communication interface 302 may include one or more transceivers. The transceiver may be a wireless transceiver, including modulation / demodulation circuitry, a digital-to-analog converter (DAC), a shaping table, an analog-to-digital converter (ADC), filters, waveform shapers, preamplifiers, power amplifiers, and / or other logic for transmission and reception via one or more antennas or (for some devices) via a physical (e.g., wired) medium. The transmitted and received signals may follow any of a wide variety of formats, protocols, modulations (e.g., QPSK, 16-QAM, 64-QAM, or 256-QAM), channels, bit rates, and encodings. As a specific example, communication interface 302 may include a transceiver supporting transmission and reception under 2G, 3G, BT, WiFi, Universal Mobile Telecommunications System (UMTS), High Speed ​​Packet Access (HSPA)+, 4G / Long Term Evolution (LTE), and 5G standards. However, the techniques described below are applicable to other wireless communication technologies, whether originating from the 3rd Generation Partnership Project (3GPP), the GSM Association, 3GPP2, IEEE, or other partners or standards bodies.

[0036] System circuitry 304 may include one or more processors 321 and memory 322. For example, memory 322 stores operating system 324, instructions 326, and parameters 328. Processor 321 is configured to execute instructions 326 to perform desired functions for UE 300. Parameters 328 can provide and specify configuration and operational options for instructions 326. Memory 322 may also store any BT, WiFi, 3G, 4G, 5G, or other data that UE 300 will send or has received via communication interface 302. In various embodiments, system power for UE 300 may be supplied by power storage devices such as batteries or transformers.

[0037] Figure 4A swimlane diagram of early TA acquisition (e.g., RACH procedure) is shown. In step 405, the network (e.g., gNB 200) may send a Radio Resource Control (RRC) configuration for early TA acquisition to UE 300. In step 410, gNB 200 may subsequently send a PDCCH command to UE 300 to trigger early TA acquisition (e.g., RACH) for the candidate cell. In step 415, the MAC entity of UE 300 may initiate a RACH procedure for early TA acquisition based on the RRC configuration received in step 405 and the PDCCH command in step 410. In step 420, UE 300 may send a preamble to gNB 200 with a specific calculated transmission power (i.e., preambleReceiverTargetPower, which will be described later). In step 425, UE 300 may consider that early TA acquisition (e.g., RACH procedure) has been completed based on some events, as will be further described later with reference to step 425.

[0038] The pre-RACH procedure can be implemented according to any of the four options. In Option 1, the RACH procedure can be a cell-specific single-shot RACH procedure. In Option 2, the RACH procedure can be a cell-specific multi-round RACH procedure. In Option 3, the RACH procedure can be a MAC-specific single-shot RACH procedure. In Option 4, the RACH procedure can be a MAC-specific multi-round RACH procedure.

[0039] In step 405, the RRC configuration obtained in advance by the TA can be implemented as follows:

[0040]

[0041] In one implementation, the RRC parameter earlyULSyncConfig can be configured in each candidate cell configuration for the RRC configuration used in LTM. In another implementation, earlyULSyncConfig may not exist in the candidate cell configuration; the absence of earlyULSyncConfig means that the RACH procedure for early TA acquisition is not supported for candidate cells.

[0042] In step 410, the PDCCH command transmitted from gNB 200 may include at least one of the following:

[0043] a. Transmission type indicator, used to indicate whether the preamble transmission triggered by the PDCCH command is a retransmission or an initial transmission.

[0044] b. Preamble ID, used to indicate the preamble index of the RACH procedure used for early TA acquisition.

[0045] c. Candidate Cell Id: Indicates the candidate cell in which the RACH procedure for early TA acquisition should be performed.

[0046] d.SSB Id: Used to indicate the quasi-co-address (QCL) relationship of the preamble transmission.

[0047] e.PRACH MASK Id: Used to indicate the timing of RACH (e.g., RO) for preamble transmission.

[0048] In step 415, in one implementation of the RACH procedure for early TA acquisition, a new cell-specific UE variable “LTM_PREAMBLE_POWER_RAMPING_COUNTER” can be introduced for the RACH procedure for early TA acquisition. If a PDCCH command for triggering RACH toward an LTM candidate cell is received, and the initial transmission of the preamble is indicated, then LTM_PREAMBLE_POWER_RAMPING_COUNTER for the indicated candidate cell can be set to “1”; if a PDCCH command for triggering RACH toward an LTM candidate cell is received, and the retransmission of the preamble is indicated, then LTM_PREAMBLE_POWER_RAMPING_COUNTER for the indicated candidate cell can remain unchanged.

[0049] In another implementation of the RACH procedure for initiating early TA acquisition, a new MAC-specific UE variable, "LTM_PREAMBLE_POWER_RAMPING_COUNTER," can be introduced for the RACH procedure for early TA acquisition. If a PDCCH command for early TA acquisition is received toward an LTM candidate cell, indicating the initial transmission of the preamble, then LTM_PREAMBLE_POWER_RAMPING_COUNTER can be set to "1"; if a PDCCH command for early TA acquisition is received toward an LTM candidate cell, indicating the retransmission of the preamble, and the LTM candidate cell is the same as the previous RACH for early TA acquisition, then LTM_PREAMBLE_POWER_RAMPING_COUNTER can remain unchanged.

[0050] In step 420, in the implementation of preamble transmission: if the RACH is initiated by a PDCCH command for an LTM candidate cell, and the preamble transmission is indicated as a retransmission, then the LTM_PREAMBLE_POWER_RAMPING_COUNTER associated with the LTM candidate cell can be incremented by 1. The LTM_PREAMBLE_RECEIVED_TARGET_POWER of the LTM candidate cell used for preamble transmission can be set to:

[0051] preambleReceiverTargetPower+DELTA_PREAMBLE+

[0052] (LTM_PREAMBLE_POWER_RAMPING_COUNTER–1)×

[0053] PREAMBLE_POWER_RAMPING_STEP+POWER_OFFSET_2STEP_RA.

[0054] In this case, POWER_OFFSET_2STEP_RA can be ignored or set to 0dB. The physical layer can be instructed to use the selected PRACH timing, the corresponding random access radio network temporary identifier (RA-RNTI) (if available), PREAMBLE_INDEX, and LTM_PREAMBLE_RECEIVED_TARGET_POWER to transmit the random access preamble.

[0055] Alternatively or additionally, during the preamble transmission in step 420, if the RACH is initiated by the PDCCH command toward the LTM candidate cell for early TA acquisition, and the previous RACH was initiated by the PDCCH command toward the same LTM candidate cell for early TA acquisition, then PREAMBLE_POWER_RAMPING_COUNTER can be incremented by 1. The PREAMBLE_RECEIVED_TARGET_POWER of the LTM candidate cell can be set to: preambleReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_POWER_RAMPING_COUNTER - 1) × PREAMBLE_POWER_RAMPING_STEP + POWER_OFFSET_2STEP_RA.

[0056] In this case, POWER_OFFSET_2STEP_RA can be ignored or set to 0dB. The physical layer can be instructed to use the selected PRACH timing, the corresponding RA-RNTI (if available), PREAMBLE_INDEX, and PREAMBLE_RECEIVED_TARGET_POWER to transmit the random access preamble.

[0057] In step 425, the implementation may consider whether the preamble RACH is a single process. In this case, the RACH can be considered complete once the preamble transmission is indicated to the lower (physical) layer.

[0058] Alternatively or additionally, step 425 may consider whether the preceding RACH is a multi-round process. In this case, the RACH can be considered complete in each of the following example scenarios. In one implementation, if an LTM cell handover MAC CE for triggering LTM is received, all RACH processes or RACH processes for early TA acquisition can be considered complete. Alternatively or additionally, if a conventional RACH is triggered, all RACH processes or RACH processes for early TA acquisition can be considered complete; in this implementation, the conventional RACH may be a RACH process not used for early TA acquisition. Alternatively or additionally, if another preceding RACH process toward a different LTM candidate cell is triggered, the preceding RACH process toward the LTM candidate cell is considered complete. Alternatively or additionally, if the RRC configuration of the LTM candidate cell is released, the preceding RACH process toward the LTM candidate cell can be considered complete.

[0059] Subsequent descriptions refer to Figure 5 Timing Advance (TA) management. In step 505, an LTM cell handover MAC CE can be received by UE 300 from source cell 501. In step 510, UE 300 can determine the currently available TA value that needs to be maintained or preserved during LTM and perform the corresponding operation. In step 515, UE 300 can perform UL transmission to one or more target cells 502 using the preserved TA value.

[0060] During step 510, in order to indicate that the currently available TA value can be maintained, the following options may be considered.

[0061] In the first option, all valid TAs or all TAGs (e.g., before cell handover) of one or more serving cells at the UE side can be maintained during LTM. In an implementation of the first option, if RACH-based LTM is triggered, all valid TAs or all TAGs of all serving cells may not be maintained; in this implementation, the UE may consider the TAT (e.g., timeAlignmentTimer) of all TAGs (e.g., time alignment groups) to be expired. If RACH-free LTM is triggered, all valid TAs or all TAGs of all serving cells can be maintained during LTM.

[0062] In the second option, the valid TA of the serving cell and / or the TAG after cell handover can be indicated by the source cell. In an implementation of the second option, the TA value and the indication of the corresponding TAG can be carried in the LTM cell handover MAC CE sent by the source cell. In this implementation, the LTM cell handover MAC CE may include at least one of the following fields: 1) TAGi field: TAG Id indicating the i-th TAG with a TA value; in one implementation, the TAGi field may be a bitmap-like field; and 2) TAi field: the absolute TA value of the i-th TAG.

[0063] Alternatively or additionally, for the second option, the TA value indication can be associated with the TAG obtained from RRC signaling and / or LTM cell handover MAC CE. Below is an example:

[0064]

[0065] During step 510, in one embodiment of the operation for the first option, the maintained TA value can be reassociated with the second TAG after the cell handover via the serving cell that also belongs to the first TAG before the cell handover. In one embodiment of the operation for the first option, the reassociation of the maintained TA value with the TAG can be performed upon receiving the LTM cell handover MAC CE. In another embodiment of the operation for the first option, the reassociation of the maintained TA value can be performed when LTM is considered complete.

[0066] During step 510, in one embodiment of the operation for the second option, the TA value can be associated with the TAG based on the LTM cell handover MAC CE or RRC signaling received from the source cell. In one embodiment of the operation for the second option, the association of the TA value with the TAG can be performed upon receiving the LTM cell handover MAC CE. In another embodiment of the operation for the second option, the association of the TA value can be performed when LTM is considered complete.

[0067] Regarding the time alignment timer (TAT) processing in step 515, two options are available. In the first option, if a cell belongs to the first TAG before cell handover and the second TAG after cell handover, the TAT associated with the first TAG can be reassociated with the second TAG upon receiving the LTM cell handover MAC CE or after LTM completion. Alternatively or additionally, upon receiving the LTM cell handover MAC CE or after LTM completion, the TAT associated with the second TAG can be started / restarted using the remaining value of the TAT associated with the first TAG of the same cell. In the second option, when applying the TA value of the TAG indicated by the LTM cell handover MAC CE or RRC signaling received from the source cell, the TAT can be started / restarted for each TAG.

[0068] refer to Figure 6The following description relates to the UL authorization of the first LTM transmission. In one embodiment, the first LTM transmission 627 / 631 may be a transmission with a DCCH message. In one embodiment, the DCCH message may be an RRC message RRCReconfigurationComplete. In step 605, UE 300 may receive the LTM RRC configuration from source cell 501. In step 610, UE 300 may receive the LTM cell handover MAC CE from source cell 501. In step 615, UE 300 may apply the RRCReconfiguration message contained in the LTM RRC configuration to the LTM candidate cell indicated by the LTM cell handover MAC CE. In step 620, if the RRCReconfiguration message is successfully applied, UE 300 may generate a DCCH message. In step 622, based on the RRC configuration of LTM and the received LTM cell handover MAC CE, UE 300 may perform an initial transmission 627 / 631 with a DCCH message for LTM according to any of the following alternative schemes (625, 630, 635): (1) UE 300 may use Dynamic Grant (DG) to perform an initial transmission 627 with a DCCH message for LTM to target cell 502 (i.e., step 625); (2) UE 300 may use Configuration Grant (CG) to perform an initial transmission 631 with a DCCH message for LTM to target cell 502 (i.e., step 630); and / or (3) UE 300 may initiate a RACH for LTM (i.e., step 635). In step 624, UE 300 may determine that LTM has been completed by at least one of the following: 1) receiving a PDCCH addressed to C-RNTI for a new transmission; 2) receiving a MAC CE with a DL transmission indicating that LTM has been successfully terminated; in this embodiment, the MAC CE may contain only a subheader field without any payload; 3) receiving a PDCCH addressed to C-RNTI for a new UL transmission with the same HARQ process ID, for which the first transmission 627 / 631 was performed; and / or 4) the RACH procedure has been successfully completed.

[0069] In one embodiment of the first UL transmission 627 / 631, the first UL transmission may be an initial transmission for LTM with a DCCH message.

[0070] In step 605, one or more ConfiguredGrantConfigs may be included in the RRC configuration of the LTM for each candidate cell. ConfiguredGrantConfig can be a configuration of multiple predefined UL authorized resources available for UL data transmission (e.g., the first transmission 627 / 631 with DCCH messages) during LTM cell handover. Each CG timing predefined in ConfiguredGrantConfig can be associated with one or more beams, which can be indicated using the SSB ID.

[0071] In this implementation, the UL grant resources allocated to LTM by configuredGrantConfig can only be used to send DCCH messages to avoid potential UP data loss. In this implementation, a new LCH restriction parameter, preAllocatedULGrant-allowed, can be introduced into logicalChannelConfig. In one implementation of preAllocatedULGrant-allowed, if the UL grant is allocated to LTM by configuredGrantConfig, only data from logical channels configured with pre-AllocatedULGrant-allowed (e.g., UL MAC SDUs) can be multiplexed and assembled into the UL grant allocated to LTM by configuredGrantConfig. In one implementation of preAllocatedULGrant-allowed, it can only be optionally configured in the LCH associated with SRB1; it should not exist for LCHs associated with radio bearers other than SRB1.

[0072] In one implementation, if the initial UL transmission 627 / 631 for LTM has already been performed and the LTM process is not considered successfully completed, the UL grant resources allocated by ConfiguredGrantConfig for LTM may not be permitted to send new UL data transmissions after the initial UL transmission 627 / 631. In another implementation, if the initial UL transmission has already been sent and the LTM process is not considered completed by the UE, the UL grant allocated by ConfiguredGrantConfig for LTM can be ignored.

[0073] In step 622, steps 625 and / or 630 can be allowed to fall back to step 635. A timer LTM-FallbackTimer can be introduced for each LTM candidate cell. Alternatively or additionally, the timer LTM-FallbackTimer can be introduced in the LTM-Config. The LTM-FallbackTimer can be a timer controlled by the MAC layer. Alternatively or additionally, the LTM-FallbackTimer can be started at the last symbol of the PUSCH transmission for the initial transmission of the first UL transmission of LTM. The LTM-FallbackTimer can be stopped by the UE 300 determining that LTM is complete (e.g., step 624). Once the LTM-FallbackTimer expires, RACH-based LTM 636 can be triggered toward the target candidate LTM cell. The length of the LTM-FallbackTimer can be shorter than the LTM supervision timer in the RRC. The fallback from step 625 to step 635 can be triggered by a PDCCH command. The rollback from steps 630 to 635 can be triggered by a counter, which counts the number of transmissions of the transport block (TB) in the initial UL transmission. In this implementation, a counter threshold can be configured for each LTM candidate cell. The counter can be implemented according to at least one of the following: 1) for each instance of the initial UL transmission with a DCCH message, the counter value can be incremented by 1; 2) if the counter value is equal to or greater than the threshold, the process can roll back to the RACH process; 3) if LTM is successfully completed, the counter can be set to 0 or 1.

[0074] If it is determined that a rollback from step 625 and / or step 630 to step 635 should be performed, at least one of the following operations may be performed: (1) resetting the MAC entity and / or clearing all UL HARQ buffers and / or treating all TAGs' TAs as expired; (2) notifying the upper layer to rollback to RACH-based LTM 636. In one implementation, the LTM supervisory timer may be started or restarted by this notification from the lower layer (e.g., the MAC layer). The supervisory timer may be used by the UE300 to determine whether LTM has been successfully completed. The expiration of the supervisory timer may indicate that LTM has not been successful. In one implementation, if a rollback indication is received from the lower layer, the RRC may regenerate the RRCReconfigurationCompleteMessage. Finally, a rollback from step 625 and / or step 630 to step 635 may also include (3) initiating a RACH procedure toward the LTM candidate cell.

[0075] Regarding steps 625 and / or 630, either a CG or a DG can be used for the transmission of the DCCH message (627 / 631) (e.g., RRCReconfigurationComplete), depending on whether a DG or a CG arrives earlier. If the dynamic uplink grant is used for the initial transmission of the first UL transmission 627 / 631, the UL grant predefined for LTM by ConfiugredGrantConfig can be ignored by the MAC entity.

[0076] Regarding step 630, when selecting the CG timing for LTM, the process can be performed as described below.

[0077] Assuming that the CG timing predefined for LTM by ConfiguredGrantConfig has been associated with one or more beams, and the LTM cell handover MAC CE received by the UE (e.g., as shown in step 610) also includes a beam indication for LTM, then the UE 300 may consider only the CG timing associated with the beam indicated by the LTM cell handover MAC CE as valid for the first UL transmission (e.g., the initial transmission 631 for LTM cell handover with a DCCH message).

[0078] If the measured RSRP of the beam indicated in the LTM cell handover MAC CE is less than a predefined threshold, and there is at least one beam whose RSRP value exceeds the predefined threshold, then UE 300 can select a beam whose RSRP value exceeds the threshold and consider the corresponding CG timing to be valid for the first UL transmission 631.

[0079] If the RSRP measurement of the beam indicated by the LTM cell handover MAC CE exceeds a predefined threshold, the corresponding CG timing can be considered valid for the first UL transmission 631.

[0080] If no SSB is available that has a CG timing associated with an RSRP value exceeding a predefined threshold, UE 300 may select a CG timing associated with the beam indicated by the LTM cell handover MAC CE for the initial UL transmission. Alternatively or additionally, UE 300 may randomly select an SSB Id and use the corresponding CG timing to transmit the initial UL transmission. Alternatively or additionally, UE 300 may determine to fall back to step 635 of RACH-based LTM.

[0081] Assuming that one or more CG timings are unrelated to the beam and that the beam indication is included in the LTM cell handover MAC CE, the most recent CG timing after the cell handover can be considered valid for the first UL transmission 631.

[0082] Regarding step 630, if automatic transmission or retransmission of the first UL transmission using CG is permitted, the following steps can be performed.

[0083] In the first step, the UE 300 can determine the validity of each CG timing for automatic transmission or retransmission of the initial UL transmission. CG timings for automatic transmission or retransmission can be considered valid by one or more of the following options: (1) CG timings associated with the same SSB ID as the initial transmission; (2) CG timings associated with SSB IDs whose RSRP measurements exceed a predefined threshold; and / or (3) CG timings associated with the same HARQ process ID as the initial transmission.

[0084] In the second step, for each valid CG timing, UE 300 can process UL grants for automatic retransmission of the first UL transmission 631. Automatic retransmission of the first transmission using the configured UL grant can be supported. A retransmission timer (e.g., LTMCGRetransmissionTimer) can be introduced into the ConfiguredGrantConfig in the RRC configuration of the LTM candidate cell. If such a timer is configured, the timer can indicate automatic retransmission of the first UL transmission using the CG. For each CG, UE 300 can consider the new data indicator (NDI) value of the CG as not having been switched if the following conditions are met: (1) LTMCGRetransmissionTimer is configured and not running; (2) the ConfiguredGrantTimer is running; and (3) a previous CG with the same HARQ process ID was used to send the first UL transmission of LTM.

[0085] Alternatively or additionally, in the second step, the automatic transmission of the first transmission can be considered a new transmission. In this case, an enumeration type parameter automaticTx-LTM can be introduced in ConfiguredGrantConfig. When this parameter exists and is true, automatic transmission of the first UL transmission is allowed. For each valid UL grant, the HARQ entity of UE300 can treat the MAC PDU of the HARQ process ID as acquired, pass the MAC PDU, UL grant, and HARQ information of the TB to the identified HARQ process, and instruct the identified HARQ process to trigger a new transmission if the following conditions are met: (1) the UL grant is a configured UL grant; (2) automaticTx-LTM is configured; (3) a previous UL grant of the same HARQ process is used for the first UL transmission of the LTM; (4) the LTM is not considered complete; and (5) none of the PUSCH transmissions scheduled using the acquired MAC PDU's CS-RNTI and / or C-RNTI have been executed.

[0086] The above description and accompanying drawings provide specific example embodiments and implementations. However, the subject matter described can be embodied in many different forms, and therefore, the covered or claimed subject matter is intended to be construed as not being limited to any of the example embodiments set forth herein. A reasonably broad scope is intended for use with the claimed or covered subject matter. Among other things, the subject matter can be embodied as a method, apparatus, component, system, or non-transitory computer-readable medium for storing computer code. Therefore, embodiments can take the form, for example, hardware, software, firmware, storage medium, or any combination thereof. For example, the method embodiments described above can be implemented by components, apparatus, or systems including memory and processor by executing computer code stored in memory.

[0087] Throughout this specification and claims, terms may have nuanced meanings implied or suggested in the context, beyond their explicitly stated meanings. Similarly, the phrase "in one embodiment / implementation" as used herein does not necessarily refer to the same embodiment, and the phrase "in another embodiment / implementation" as used herein does not necessarily refer to different embodiments. For example, the claimed subject matter is intended to include, in whole or in part, combinations of exemplary embodiments.

[0088] Generally, terms can be understood, at least in part, from their usage in context. For example, terms such as “and,” “or,” or “and / or” as used herein can include a variety of meanings, which can depend at least in part on the context in which such terms are used. Typically, if “or” is used to relate a list, such as A, B, or C, it is intended to mean A, B, and C, used here in an inclusive sense, and A, B, or C, used here in an exclusive sense. Furthermore, depending at least in part on the context, the term “one or more,” as used herein, can be used to describe either any feature, structure, or characteristic in a singular sense or a combination of features, structures, or characteristics in a plural sense. Similarly, terms such as “a,” “an,” or “the” can be understood, at least in part on the context, to express either a singular or a plural usage. Moreover, the term “based on” can be understood not necessarily to express an exclusive set of factors, but again can, at least in part on the context, allow for additional factors that are not necessarily explicitly described.

[0089] References to features, advantages, or similar language throughout this specification do not imply that all features and advantages achievable using this solution should be or are included in any single implementation thereof. Rather, language relating to features and advantages is to be understood as meaning that a particular feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of this solution. Therefore, the discussion of features and advantages, as well as similar language, throughout this specification may, but does not necessarily, refer to the same embodiments.

[0090] Furthermore, the features, advantages, and characteristics described in this solution can be combined in any suitable manner in one or more embodiments. Those skilled in the art will recognize that, in light of the description herein, this solution can be practiced without one or more specific features or advantages of a particular embodiment. In other cases, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of this solution.

[0091] Among other things, the subject matter of this disclosure may also cover or include the following:

[0092] In a first aspect, a method for providing advance time advance (TA) acquisition includes: receiving a radio resource control (RRC) configuration for advance TA acquisition from a base station; receiving a PDCCH command from the base station to trigger a random access channel (RACH) toward a candidate cell; initiating an RACH procedure for advance TA acquisition based on the received RRC configuration and the PDCCH command; and transmitting a preamble to the base station on the candidate cell at a calculated transmission power.

[0093] The second aspect includes the method according to aspect 1, wherein the PDCCH command includes at least one of the following indications: a transmission type indication indicating whether the preamble is a retransmission or an initial transmission; a preamble ID indicating the preamble for the RACH procedure obtained in advance TA; an LTM candidate ID indicating the candidate cell in which the preamble is transmitted; an SSB ID indicating the SSB with a quasi-co-location (QCL) relationship to the preamble transmission; or an RO mask index indicating the RACH timing of the preamble transmission.

[0094] The third aspect includes the method according to any of the foregoing aspects, wherein the RACH initiation process toward the candidate cell further includes: determining that the PDCCH command indicates the initial transmission of the preamble, and then setting a counter associated with the candidate cell to 1; and determining that the PDCCH command indicates the retransmission of the preamble for the candidate cell, and then keeping the counter value unchanged.

[0095] The fourth aspect includes the method according to any of the foregoing aspects, wherein initiating a RACH procedure toward a candidate cell further includes: determining that the PDCCH command indicates the initial transmission of the preamble; then setting a counter to 1; and determining that the PDCCH command indicates the retransmission of the preamble and that the candidate cell is the same candidate cell toward which the previous RACH procedure was directed, and then keeping the counter value unchanged.

[0096] The fifth aspect includes the method according to any of the foregoing aspects, wherein transmitting the preamble on the candidate cell further includes: determining that the PDCCH command indicates a retransmission of the preamble; incrementing a counter associated with the candidate cell by 1; and setting a target power for preamble transmission on the candidate cell based on the counter.

[0097] The sixth aspect includes the method according to any of the foregoing aspects, wherein transmitting the preamble on the candidate cell further includes: determining that the PDCCH command indicates a retransmission of the preamble and that the previous RACH procedure was performed on the same candidate cell; incrementing a counter by 1; and setting a target power for preamble transmission on the candidate cell based on the counter.

[0098] The seventh aspect includes the method according to any of the foregoing aspects, further comprising: determining that a RACH for TA acquisition toward a candidate cell is completed when: the transmission of a preamble indicated in a PDCCH command is indicated to the lower layer; an LTM cell handover MAC CE for triggering LTM is received; a RACH for TA acquisition toward a different candidate cell is triggered; or the RRC configuration of the candidate cell is released.

[0099] The eighth aspect includes a method for providing uplink (UL) authorization for a dedicated control channel (DCCH) message, comprising: receiving a radio resource control (RRC) configuration for L1 / L2 triggered mobility (LTM) from a source cell; receiving an LTM cell handover command (MAC CE) from the source cell; applying the RRC configuration of an LTM candidate cell indicated by the LTM cell handover command (MAC CE); generating a DCCH message in response to the RRC configuration of the LTM candidate cell; transmitting an initial transmission to a target cell; and determining that LTM was successfully completed.

[0100] The ninth aspect includes the method according to aspect 8, wherein transmitting the first transmission further includes: transmitting the first transmission using dynamic grant (DG) based on RRC configuration and LTM cell handover MAC CE.

[0101] The tenth aspect includes the method according to aspect 8 or 9, wherein transmitting the first transmission further includes: transmitting the first transmission using configuration grant (CG) based on RRC configuration and LTM cell handover MAC CE.

[0102] The eleventh aspect includes the method according to aspects 8 to 10, wherein transmitting the first transmission further includes: initiating a RACH procedure for LTM based on RRC configuration and LTM cell handover MAC CE.

[0103] The twelfth aspect includes the method according to aspects 8 to 11, wherein the RRC configuration further includes ConfiguredGrantConfig, which configures a plurality of predefined UL grant resources for UL data transmission.

[0104] The thirteenth aspect includes the method according to aspects 8 to 12, wherein, for UL-granted resources allocated by ConfiguredGrantConfig and included in the RRC configuration, only data from logical channels configured with logical channel (LCH) restrictions can be multiplexed and reassembled.

[0105] The fourteenth aspect includes the method according to aspects 8 to 13, wherein, if the first transmission of LTM has been performed and LTM is not considered to have been successfully completed, the UL authorized resources allocated by ConfiguredGrantConfig are ignored.

[0106] The fifteenth aspect includes the method described in aspects 8 to 14, further comprising: introducing a backoff timer for each LTM candidate.

[0107] The sixteenth aspect includes the method according to aspects 8 to 15, further comprising: starting a back-back timer at the last symbol of a PUSCH transmission with an initial transmission of a DCCH message for LTM.

[0108] The seventeenth aspect includes the method according to aspects 8 to 16, further comprising: stopping the backoff timer after receiving an ACK for the PUSCH transmission used for the initial UL transmission.

[0109] The eighteenth aspect includes the method described in aspects 8 to 17, and further includes: triggering a RACH-based LTM after the rollback timer expires.

[0110] The nineteenth aspect includes the method described in aspects 8 to 18, and further includes: triggering a fallback to a RACH-based LTM based on a PDCCH command.

[0111] The twentieth aspect includes the method according to aspects 8 to 19, wherein the RRC configuration further includes ConfiguredGrantConfig, which configures a plurality of predefined UL grant resources for UL data transmission.

[0112] The twenty-first aspect includes the method according to aspects 8 to 20, further comprising: resetting the MAC entity to clear the UL buffer for initial transmission; notifying the upper layer of backoff; and / or initiating RACH-based LTM toward LTM candidate cells.

[0113] The twenty-second aspect includes the method according to aspects 8 to 21, wherein a CG timing predefined by configuredGrantConfig is associated with one or more beams, the LTM cell handover MAC CE includes a beam indication for LTM, and the method further includes: determining that the measured RSRP of the beam indicated by the LTM cell handover MAC CE is less than a predefined threshold, and that there is at least one beam with an RSRP value exceeding the predefined threshold; selecting the beam exceeding the predefined threshold; and considering that the corresponding configuration grant (CG) is valid for the first transmission.

[0114] The twenty-third aspect includes the method according to aspects 8 to 22, wherein the CG timing predefined by configuredGrantConfig is associated with one or more beams, the LTM cell handover MAC CE includes beam indication for LTM, and the method further includes: determining that the RSRP measurement of the beam indicated by the LTM cell handover MAC CE exceeds a predefined threshold; and considering that the corresponding configuration grant (CG) is valid for the first transmission.

[0115] The twenty-fourth aspect includes the method according to aspects 8 to 23, wherein a CG timing predefined by configuredGrantConfig is associated with one or more beams, the LTM cell handover MAC CE includes a beam indication for LTM, and the method further includes: determining that there is no SSB with an RSRP value exceeding a predefined threshold; and considering that the configuration grant (CG) associated with the beam indicated by the LTM cell handover MAC CE is valid for the first transmission.

[0116] The twenty-fifth aspect includes the method according to aspects 8 to 24, wherein the CG timing predefined by configuredGrantConfig is associated with one or more beams, the LTM cell handover MAC CE includes beam indication for LTM, and the method further includes: determining that there is no SSB with an RSRP value exceeding a predefined threshold; and randomly selecting an SSB Id and considering the corresponding configuration grant (CG) for the first transmission.

[0117] The twenty-sixth aspect includes the method according to aspects 8 to 25, further comprising: when the initial transmission of the first transmission has been performed, determining the validity of a configuration grant (CG) predefined by ConfiguredGrantConfig for automatic transmission or retransmission, including: the CG being associated with an SSB ID that is the same as the initial transmission of the first transmission; the CG being associated with an SSB ID whose RSRP measurement result exceeds a predefined threshold; and / or the CG being associated with a HARQ process ID that is the same as the initial transmission of the first transmission.

[0118] The twenty-seventh aspect includes the method according to aspects 8 to 26, further comprising: for each valid configuration authorization (CG), processing a configuration UL authorization for automatic transmission or retransmission for the first transmission.

[0119] The twenty-eighth aspect includes the method according to aspects 8 to 27, wherein the RRC configuration further includes ConfiguredGrantConfig, which configures a plurality of predefined UL authorized resources for UL data transmission, and ConfiguredGrantConfig specifies a retransmission timer that indicates automatic retransmission for the first transmission using CG.

[0120] The twenty-ninth aspect includes the method described according to aspects 8 to 28, further comprising: for each CG, if the following condition is met, the new data indicator (NDI) value of the CG is considered not to have been switched:

[0121] The retransmission timer is configured and not running; the CG timer is running; and a previous CG with the same HARQ process ID was used to send the first transmission of LTM.

[0122] The thirtieth aspect includes the method according to aspects 8 to 29, wherein ConfiguredGrantConfig specifies parameters that allow automatic transfer on the first transfer.

[0123] The thirty-first aspect includes the method according to aspects 8 to 30, further comprising: for each UL grant, the HARQ entity: treating the MAC PDU of the HARQ process ID as identified, passing the MAC PDU, UL grant, and HARQ information of the transport block to the identified HARQ process, and instructing the identified HARQ process to trigger a new transport when: the UL grant is a configured UL grant; parameters are configured; a previous UL grant for the same identified HARQ process is used to send the first transport after LTM completion; LTM is not completed; and multiple PUSCH transports scheduled using the CS-RNTI of the MAC PDU have not been executed.

[0124] The thirty-second aspect includes a method for providing advance time advance (TA) acquisition in a user equipment (UE), comprising: receiving an L1 / L2 triggered mobility (LTM) cell handover MAC CE from a source cell; determining a TA value to be maintained during the LTM; and transmitting the maintained TA value to a target cell.

[0125] The thirty-third aspect includes the method according to aspect 32, wherein the LTM is a RACH-based LTM, and determining the TA values ​​to be maintained during the LTM further includes: determining that the valid TAs of all serving cells are invalid and will not be maintained.

[0126] The thirty-fourth aspect includes the method according to aspect 32 or 33, wherein the LTM is a RACH-free LTM, and determining the TA value to be maintained during the LTM further includes: determining that the valid TA of all serving cells is valid and will be maintained.

[0127] The thirty-fifth aspect includes the method according to aspects 32 to 34, wherein determining the TA value to be maintained during LTM further includes: indicating the TA value to be maintained in the LTM cell handover MAC CE, including: indicating that the TA value exists in the TAG ID of the i-th TAG in the cell that is still the serving cell, wherein the TA value of the i-th TAG is an absolute TA value.

[0128] The thirty-sixth aspect includes the method according to aspects 32 to 35, wherein determining the TA value to be maintained during LTM further includes: obtaining the TA value to be maintained from the association with the TAG by means of an indication from RRC signaling and / or LTM cell handover MAC CE.

[0129] The thirty-seventh aspect includes the method according to aspects 32 to 36, wherein transmitting the maintained TA value to the target cell further includes: applying the TA value to be maintained; and associating a new TAG with a time alignment timer (TAT) after applying the TA value.

[0130] The thirty-eighth aspect includes the method described in aspects 32 to 37, further comprising: using the remaining value of the TAT associated with a TAG belonging to the same cell to start and / or restart the TAT.

[0131] The thirty-ninth aspect includes the method according to aspects 32 to 38, further comprising: when applying the TA value of a TAG indicated by the LTM cell handover MACCE or RRC signaling, starting and / or restarting the TAT for each TAG.

Claims

1. A method for providing lead time advance (TA) acquisition, the method comprising: Receive the Radio Resource Control (RRC) configuration obtained in advance from the base station using the advance TA; Receive a PDCCH command from the base station to trigger a random access channel (RACH) toward the candidate cell; Based on the received RRC configuration and PDCCH command, initiate the RACH process for the advance TA acquisition; as well as The preamble is transmitted to the base station on the candidate cell with a calculated transmission power.

2. The method according to claim 1, wherein, The PDCCH command includes at least one of the following indications: Transmission type indicator, which indicates whether the preamble is a retransmission or an initial transmission; Preamble ID, used to indicate the preamble used in the RACH procedure for early TA acquisition; LTM candidate ID, used to indicate the candidate cell in which the preamble is transmitted; SSBId is used to indicate the SSB that has a quasi-co-address (QCL) relationship with the SSB in the preamble transmission; or The RO mask index is used to indicate the RACH timing of the preamble transmission.

3. The method according to claim 1, wherein, The RACH process of initiating the RACH toward the candidate cell also includes: The PDCCH command is determined to indicate the initial transmission of the preamble, and then the counter associated with the candidate cell is set to 1; and The PDCCH command is determined to indicate the retransmission of the preamble for the candidate cell, and then the counter value is kept unchanged.

4. The method according to claim 1, wherein, The RACH process of initiating the RACH toward the candidate cell also includes: The PDCCH command is determined to indicate the initial transmission of the preamble, and then the counter is set to 1; and Determine that the PDCCH command indicates a retransmission of the preamble, and that the candidate cell is the same candidate cell that the previous RACH procedure was directed towards, then keep the counter value unchanged.

5. The method according to claim 1, wherein, Transmitting the preamble on the candidate cell also includes: Determine that the PDCCH command indicates a retransmission of the preamble; Increment the counter associated with the candidate cell by 1; and The target power for preamble transmission on the candidate cell is set based on the counter.

6. The method according to claim 1, wherein, Transmitting the preamble on the candidate cell also includes: It is determined that the PDCCH command indicates a retransmission of the preamble, and that the previous RACH procedure was performed on the same candidate cell; Increment the counter by 1; and The target power for preamble transmission on the candidate cell is set based on the counter.

7. The method according to claim 2, further comprising: The RACH for TA acquisition, which is directed toward the candidate cell, is completed when at least one of the following conditions is met: The transmission of the preamble indicated in the PDCCH command is instructed to the lower layer; The LTM cell handover MAC CE used to trigger LTM is received; RACH for TA acquisition is triggered towards different candidate cells; or The RRC configuration of the candidate cell is released.

8. A method for providing uplink (UL) authorization for a Dedicated Control Channel (DCCH) message, the method comprising: Receive the Radio Resource Control (RRC) configuration for L1 / L2 Triggered Mobility (LTM) from the source cell; Receive LTM cell handover command MAC CE from the source cell; Apply the RRC configuration of the LTM candidate cell indicated by the LTM cell handover command MAC CE; In response to the RRC configuration of the LTM candidate cell, a DCCH message is generated; Send the initial transmission to the target cell; as well as The LTM was confirmed to have been successfully completed.

9. The method according to claim 8, wherein, The initial transmission also includes: Based on the aforementioned RRC configuration and LTM cell handover MAC CE: The initial transmission is delivered using Dynamic Grant (DG).

10. The method according to claim 8, wherein, The initial transmission also includes: Based on the aforementioned RRC configuration and LTM cell handover MAC CE: The initial transmission is delivered using Configuration Grant (CG).

11. The method according to claim 8, wherein, The initial transmission also includes: Based on the RRC configuration and LTM cell handover MAC CE, initiate the RACH procedure for LTM.

12. The method according to claim 8, wherein, The RRC configuration also includes ConfiguredGrantConfig, which configures multiple predefined UL authorization resources for UL data transmission.

13. The method according to claim 12, wherein, For UL-granted resources allocated by ConfiguredGrantConfig and included in the RRC configuration, only data from logical channels configured with logical channel (LCH) restrictions can be multiplexed and reassembled.

14. The method according to claim 12, wherein, If the first transfer of LTM has been performed and the LTM is not considered to have been successfully completed, the UL authorized resources allocated by ConfiguredGrantConfig are ignored.

15. The method according to claim 8, further comprising: A backoff timer is introduced for each LTM candidate.

16. The method according to claim 15, further comprising: The backoff timer is started at the last symbol of the PUSCH transmission with the initial transmission of the DCCH message used for LTM.

17. The method according to claim 15, further comprising: The backoff timer is stopped upon receiving an ACK for the PUSCH transmission used for the initial UL transmission.

18. The method according to claim 15, further comprising: A RACH-based LTM is triggered after the rollback timer expires.

19. The method according to claim 9, further comprising: The fallback to RACH-based LTM is triggered by the PDCCH command.

20. The method according to claim 18 or 19, further comprising: Reset the MAC entity to clear the UL buffer for the first transfer; Notify the upper management to roll back; and / or Initiate RACH-based LTM towards the LTM candidate cell.

21. The method according to claim 8, wherein, The CG timing, predefined by configuredGrantConfig, is associated with one or more beams. The LTM cell handover MAC CE includes beam indication for LTM, and The method further includes: The configuration grant (CG) associated with the beam indicated by the LTM cell handover MAC CE is considered to be valid for the first transmission.

22. The method according to claim 8, wherein, The CG timing, predefined by configuredGrantConfig, is associated with one or more beams. The LTM cell handover MAC CE includes beam indication for LTM, and The method further includes: Determine the following items: The measured RSRP of the beam indicated by the LTM cell handover MAC CE is less than a predefined threshold, and There is at least one beam whose RSRP value exceeds the predefined threshold; Select a beam exceeding the predefined threshold; and The corresponding configuration authorization (CG) is considered valid for the first transmission.

23. The method according to claim 8, wherein, The CG timing, predefined by configuredGrantConfig, is associated with one or more beams. The LTM cell handover MAC CE includes beam indication for LTM, and the method further includes: The measured RSRP of the beam indicated by the LTM cell handover MAC CE is determined to exceed a predefined threshold; and The corresponding configuration authorization (CG) is considered valid for the first transmission.

24. The method according to claim 8, wherein, The CG timing, predefined by configuredGrantConfig, is associated with one or more beams. The LTM cell handover MAC CE includes beam indication for LTM, and the method further includes: It was determined that there were no SSBs with RSRP values ​​exceeding a predefined threshold; and The configuration grant (CG) associated with the beam indicated by the LTM cell handover MAC CE is considered to be valid for the first transmission.

25. The method according to claim 8, wherein, The CG timing, predefined by configuredGrantConfig, is associated with one or more beams. The LTM cell handover MAC CE includes beam indication for LTM, and the method further includes: It was determined that there were no SSBs with RSRP values ​​exceeding a predefined threshold; and Randomly select an SSB ID and assume that the corresponding configuration authorization (CG) is used for the first transmission.

26. The method according to claim 8, further comprising: When the initial transmission of the first transmission has been performed, determine the validity of the configuration authorization (CG) predefined by ConfiguredGrantConfig used for automatic transmission or retransmission, including: The CG is associated with the SSB ID, which is the same as the initial transmission of the first transmission; The CG is associated with the RSRP measurement result exceeding a predefined threshold SSB Id; and / or The CG is associated with the same HARQ process ID as the initial transmission of the first transmission.

27. The method according to claim 26, further comprising: For each valid configuration license (CG), process the configuration UL license for automatic transmission or retransmission for the first transmission.

28. The method according to claim 27, wherein, The RRC configuration also includes ConfiguredGrantConfig, which configures multiple predefined UL grant resources for UL data transmission, and The ConfiguredGrantConfig specifies a retransmission timer that indicates support for automatic retransmission of the first transmission using the CG.

29. The method according to claim 28, further comprising: For each CG, the New Data Indicator (NDI) value of that CG is considered not to have been switched if the following condition is met: The retransmission timer has been configured but not running; The CG timer is running; and A previous CG with the same HARQ process ID was used to send the first transmission of LTM.

30. The method according to claim 26, wherein, The ConfiguredGrantConfig parameter specifies the parameters that allow automatic transfers on the first transfer.

31. The method according to claim 30, further comprising: For each UL authorization, the HARQ entity: The MAC PDU of the HARQ process ID is considered identified. The MAC PDU, the UL authorization, and the HARQ information of the transport block are passed to the identified HARQ process, and Instruct the identified HARQ process to trigger a new transport under the following conditions: The UL authorization mentioned refers to configuring UL authorization; The parameters have been configured; The previous UL authorization for the same identified HARQ process was used for the first transmission completed by LTM; The LTM was not completed; as well as Multiple PUSCH transfers scheduled using the CS-RNTI of the MAC PDU were not executed.

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