Timing advance verification techniques for L1 / L2 inter-cell mobility

Abstract

A method of wireless communication at a UE is disclosed. The method includes transmitting, at a first time instance, an indication of a first measurement for at least one DL-RS associated with a first cell, wherein the first cell is included in a set of cells of an L1 mobility configuration or a set of cells of an L2 mobility configuration. The method includes receiving an estimated TA associated with the first cell at a second time instance following the first time instance. The method includes performing a second measurement on the at least one DL-RS. The method includes accepting or rejecting the estimated TA for communication with the first cell based on at least one of the first measurement or the second measurement.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. patent application serial number 17 / 822,084, filed on August 24, 2022, entitled “TIMING ADVANCE VALIDATION TECHNIQUES FOR L1 / L2 INTER-CELL MOBILITY,” which is expressly incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates generally to communication systems, and more particularly to timing advance (TA). Background Art

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephony, video, data, messaging, and broadcast. Typical wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a city, country, region, and even global level. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of the continuous mobile broadband evolution promulgated by the Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)) and other requirements. 5GNR includes services associated with enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low latency communication (URLLC). Certain aspects of 5G NR may be based on 4G Long Term Evolution (LTE) standards. It is necessary to further improve 5G NR technology. In addition, these improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies. Summary of the invention

[0006] A simplified summary of one or more aspects is presented below to provide a basic understanding of these aspects. This summary is not an extensive review of all contemplated aspects. This summary neither identifies the key or important elements of all aspects, nor describes the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description presented later.

[0007] In one aspect of the present disclosure, a method, computer-readable medium, and apparatus for wireless communication at a user equipment (UE) are provided. The apparatus includes a memory and at least one processor, the at least one processor is coupled to the memory, and based at least in part on information stored in the memory, the at least one processor is configured to: send an indication of a first measurement for at least one downlink reference signal (DL-RS) associated with a first cell at a first time instance, wherein the first cell is included in a cell set of a layer 1 (L1) mobility configuration or a cell set of a layer 2 (L2) mobility configuration; receive an estimated timing advance (TA) associated with the first cell at a second time instance after the first time instance; perform a second measurement on the at least one DL-RS; and accept or reject the estimated TA for communication with the first cell based on at least one of the first measurement or the second measurement.

[0008] In one aspect of the present disclosure, a method, computer-readable medium, and apparatus for wireless communication at a network entity are provided. The apparatus includes a memory and at least one processor, the at least one processor is coupled to the memory, and based at least in part on information stored in the memory, the at least one processor is configured to: receive an indication of a first measurement of at least one downlink reference signal (DL-RS) associated with a first cell at a first time instance, wherein the first cell is included in a cell set of a layer 1 (L1) mobility configuration or a cell set of a layer 2 (L2) mobility configuration; estimate a timing advance (TA) associated with the first cell based on the first measurement of the at least one DL-RS; and send the estimated TA associated with the first cell at a second time instance after the first time instance.

[0009] To achieve the aforementioned and related purposes, one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail some exemplary features of one or more aspects. However, these features indicate only some of the various ways in which the principles of the various aspects can be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network.

[0011] Figure 2A is a diagram illustrating an example of a first frame according to various aspects of the present disclosure.

[0012] Figure 2B is a diagram illustrating an example of downlink (DL) channels within a subframe according to various aspects of the present disclosure.

[0013] Figure 2C is a diagram illustrating an example of a second frame according to various aspects of the present disclosure.

[0014] Figure 2D is a diagram illustrating an example of uplink (UL) channels within a subframe according to various aspects of the present disclosure.

[0015] Figure 3 is a diagram illustrating an example of a base station and a user equipment (UE) in an access network.

[0016] Figure 4 is a diagram illustrating an example cell designation.

[0017] Figure 5 is a diagram illustrating an example timing adjustment group (TAG).

[0018] Figure 6 is a diagram illustrating an example in which a UE calculates a DL timing difference and receives a TA.

[0019] Figure 7 is a diagram illustrating an example of TA verification at the UE side.

[0020] Figure 8 is a diagram illustrating example communications between a UE and a base station.

[0021] Fig. 9 is a diagram illustrating example communications between a UE, a special cell (SpCell), and a cell to be activated.

[0022] Fig.10 is a diagram illustrating example communications between a UE, a SpCell and a cell to be activated.

[0023] Fig.11 is a flow chart of a method of wireless communication.

[0024] Fig.12 is a flow chart of a method of wireless communication.

[0025] Fig.13 is a flow chart of a method of wireless communication.

[0026] Fig.14 is a flow chart of a method of wireless communication.

[0027] Fig.15 are diagrams illustrating examples of hardware implementations for example apparatuses and / or network entities.

[0028] Fig.16 is a diagram illustrating an example of a hardware implementation for an example network entity. DETAILED DESCRIPTION

[0029] The UE may apply a TA to UL transmissions with a cell to take into account the propagation delay between the UE and the cell. When the UE receives signaling from the network for connecting to a cell to be activated in a cell set configured with L1 / L2 mobility, the network may provide an estimated TA to the UE, wherein the estimated TA may be based on a measurement report sent by the UE to the network. However, the estimated TA may be inaccurate. Applying an inaccurate TA to UL transmissions may affect communication reliability. Various techniques for UE-side TA verification are described herein, which may utilize reference signal received power (RSRP) measurements to represent channel strength. In an example, a UE sends an indication of a first measurement for at least one DL-RS associated with a first cell at a first time instance, wherein the first cell is included in a cell set configured with L1 mobility or a cell set configured with L2 mobility. The UE receives an estimated TA associated with the first cell at a second time instance after the first time instance. The UE performs a second measurement on the at least one DL-RS. The UE accepts or rejects the estimated TA for communication with the first cell based on at least one of the first measurement or the second measurement. Through the above TA verification process, the UE may be able to reject an inaccurate TA. Therefore, the TA verification process may lead to improved communication reliability.

[0030] The specific embodiments described below in conjunction with the accompanying drawings are descriptions of various configurations and do not represent the only configurations in which the concepts described herein can be practiced. In order to provide a thorough understanding of the various concepts, the specific embodiments include specific details. However, these concepts can be practiced without these specific details. In some cases, well-known structures and components are shown in block diagram form to avoid blurring such concepts.

[0031] Several aspects of telecommunication systems are presented with reference to various apparatus and methods. These apparatus and methods are described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0032] As an example, an element, or any part of an element, or any combination of elements can be implemented as a "processing system", which includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gate logic components, discrete hardware circuits, and other suitable hardware configured to perform various functionalities described throughout the present disclosure. One or more processors in a processing system can execute software. Whether referred to as software, firmware, middleware, microcode, hardware description language, or other terms, software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, or any combination thereof.

[0033] Thus, in one or more example aspects, implementations, and / or use cases, the described functionality may be implemented in hardware, software, or any combination thereof. If implemented in software, the functionality may be stored or encoded as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media. Storage media may be any available media that can be accessed by a computer. As an example, such computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of these types of computer-readable media, or any other media that can be used to store computer-executable code in the form of instructions or data structures that can be accessed by a computer.

[0034] Although various aspects, specific implementations and / or use cases are described in this application by the illustration of some examples, additional or different aspects, specific implementations and use cases may be generated in many different arrangements and scenarios. The various aspects, specific implementations and / or use cases described herein can be implemented across many different platform types, devices, systems, shapes, sizes and packaging arrangements. For example, various aspects, specific implementations and / or use cases can be generated via integrated chip specific implementations and other devices based on non-module components (e.g., end-user devices, vehicles, communication equipment, computing equipment, industrial equipment, retail / purchase equipment, medical equipment, devices that enable artificial intelligence (AI), etc.). Although some examples may or may not be specifically for use cases or applications, the described examples may have a wide range of applicability. Various aspects, specific implementations and / or use cases may be in the range from chip-level or modular components to non-modular, non-chip-level specific implementations, and further to the range of aggregated, distributed or original equipment manufacturer (OEM) devices or systems in conjunction with one or more technologies herein. In some actual settings, the equipment combined with the various aspects and features described may also include additional components and features for implementing and practicing the claimed and described aspects. For example, the transmission and reception of wireless signals necessarily include multiple components for analog and digital purposes (e.g., hardware components including antennas, RF chains, power amplifiers, modulators, buffers, processors, interleavers, adders / summers, etc.) The various techniques described herein can be practiced in a wide variety of devices of various sizes, shapes, and configurations, chip-level components, systems, distributed arrangements, aggregated or disaggregated components, end-user devices, etc.

[0035] The deployment of a communication system (such as a 5G NR system) can be arranged with various components or constituent parts in a variety of ways. In a 5G NR system or network, a network node, a network entity, a mobility element of a network, a radio access network (RAN) node, a core network node, a network element or a network equipment (such as a base station (BS), or one or more units (or one or more components) that perform base station functionality can be implemented in an aggregated architecture or a decomposed architecture. For example, a BS (such as a Node B (NB), an evolved NB (eNB), an NR BS, a 5G NB, an access point (AP), a transmit receive point (TRP) or a cell, etc.) can be implemented as an aggregated base station (also referred to as an independent BS or a monolithic BS) or a decomposed base station.

[0036] A converged base station may be configured to utilize a radio protocol stack physically or logically integrated within a single RAN node. A decomposed base station may be configured to utilize a protocol stack physically or logically distributed between two or more units, such as one or more central or centralized units (CUs), one or more distributed units (DUs), or one or more radio units (RUs). In some aspects, a CU may be implemented within a RAN node, and one or more DUs may be co-located with the CU, or alternatively, may be geographically or virtually distributed in one or more other RAN nodes. A DU may be implemented to communicate with one or more RUs. Each of a CU, a DU, and a RU may be implemented as a virtual unit, i.e., a virtual central unit (VCU), a virtual distributed unit (VDU), or a virtual radio unit (VRU).

[0037] Base station operation or network design may take into account the aggregated nature of base station functionality. For example, a disaggregated base station may be used in an integrated access backhaul (IAB) network, an open radio access network (O-RAN (network configuration such as that initiated by the O-RAN Alliance)), or a virtualized radio access network (vRAN, also known as a cloud radio access network (C-RAN)). Decomposition may include distributing functionality across two or more units at various physical locations, as well as virtually distributing functionality of at least one unit, which may enable flexibility in network design. Individual units of a disaggregated base station or disaggregated RAN architecture may be configured for wired or wireless communication with at least one other unit.

[0038] Figure 1 1 is a diagram 100 illustrating an example of a wireless communication system and an access network. The illustrated wireless communication system includes a disaggregated base station architecture. The disaggregated base station architecture may include one or more CUs 110 that may communicate directly with a core network 120 via a backhaul link, or indirectly with the core network 120 through one or more disaggregated base station units, such as a near real-time (near RT) RAN intelligent controller (RIC) 125 via an E2 link, or a non-real-time (non-RT) RIC 115 associated with a service management and orchestration (SMO) framework 105, or both. The CU 110 may communicate with one or more DUs 130 via corresponding midhaul links, such as an F1 interface. The DU 130 may communicate with one or more RUs 140 via corresponding fronthaul links. The RU 140 may communicate with corresponding UEs 104 via one or more radio frequency (RF) access links. In some implementations, a UE 104 may be served simultaneously by multiple RUs 140.

[0039] Each of these units (i.e., CU 110, DU 130, RU 140, and near-RT RIC 125, non-RT RIC 115, and SMO framework 105) may include or be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each of these units or an associated processor or controller that provides instructions to the communication interface of these units may be configured to communicate with one or more of the other units via a transmission medium. For example, these units may include a wired interface configured to receive signals or transmit signals to one or more of the other units via a wired transmission medium. Additionally, these units may include a wireless interface that may include a receiver, transmitter, or transceiver (such as an RF transceiver) configured to receive and / or transmit signals to one or more of the other units via a wireless transmission medium.

[0040] In some aspects, CU 110 may host one or more higher layer control functions. Such control functions may include radio resource control (RRC), packet data convergence protocol (PDCP), service data adaptation protocol (SDAP), etc. Each control function may be implemented using an interface that is configured to communicate signals with other control functions hosted by CU 110. CU 110 may be configured to handle user plane functionality (i.e., central unit-user plane (CU-UP)), control plane functionality (i.e., central unit-control plane (CU-CP)), or a combination thereof. In some specific implementations, CU 110 may be logically split into one or more CU-UP units and one or more CU-CP units. When implemented in an O-RAN configuration, the CU-UP unit may communicate bidirectionally with the CU-CP unit via an interface (such as an E1 interface). As needed, CU 110 may be implemented to communicate with DU 130 for network control and signaling.

[0041] DU 130 may correspond to a logical unit that includes one or more base station functions for controlling the operation of one or more RUs 140. In some aspects, DU 130 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, etc.) at least in part according to a functional split such as those defined by 3GPP. In some aspects, DU 130 may also host one or more low PHY layers. Each layer (or module) may be implemented using an interface that is configured to communicate signals with other layers (and modules) hosted by DU 130 or with control functions hosted by CU 110.

[0042] The lower layer functionality may be implemented by one or more RUs 140. In some deployments, the RU 140 controlled by the DU 130 may correspond to a logical node that hosts RF processing functions or low PHY layer functions (such as performing Fast Fourier Transform (FFT), Inverse FFT (iFFT), digital beamforming, physical random access channel (PRACH) extraction and filtering, etc.), or both, based at least in part on a functional split (such as a lower layer functional split). In such an architecture, the RU 140 may be implemented to handle over-the-air (OTA) communications with one or more UEs 104. In some implementations, real-time and non-real-time aspects of communicating with the control plane and user plane of the RU 140 may be controlled by the corresponding DU 130. In some scenarios, this configuration may enable the implementation of the DU 130 and the CU 110 in a cloud-based RAN architecture (such as a vRAN architecture).

[0043] The SMO framework 105 may be configured to support RAN deployment and provisioning of non-virtualized network elements and virtualized network elements. For non-virtualized network elements, the SMO framework 105 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements, which may be managed via an operation and maintenance interface (such as an O1 interface). For virtualized network elements, the SMO framework 105 may be configured to interact with a cloud computing platform (such as an open cloud (O-Cloud) 190) to perform network element lifecycle management (such as instantiating virtualized network elements) via a cloud computing platform interface (such as an O2 interface). Such virtualized network elements may include, but are not limited to, CU 110, DU 130, RU 140, and near-RT RIC 125. In some specific implementations, the SMO framework 105 may communicate with hardware aspects of the 4G RAN (such as an open eNB (O-eNB) 111) via the O1 interface. Additionally, in some specific implementations, the SMO framework 105 may communicate directly with one or more RUs 140 via the O1 interface. The SMO framework 105 may also include a non-RT RIC 115 configured to support the functionality of the SMO framework 105 .

[0044] The non-RT RIC 115 may be configured to include logic functions that enable non-real-time control and optimization of RAN elements and resources, artificial intelligence (AI) / machine learning (ML) (AI / ML) workflows including model training and updating, or policy-based guidance of applications / features in the near-RT RIC 125. The non-RT RIC 115 may be coupled to or in communication with the near-RT RIC 125 (such as via an A1 interface). The near-RT RIC 125 may be configured to include logic functions that enable near-real-time control and optimization of RAN elements and resources via data collection and actions through an interface (such as via an E2 interface) that connects one or more CUs 110, one or more DUs 130, or both, and the O-eNB with the near-RT RIC 125.

[0045] In some implementations, in order to generate an AI / ML model to be deployed in the near-RT RIC 125, the non-RT RIC 115 may receive parameters or external enrichment information from an external server. Such information may be utilized by the near-RT RIC 125 and may be received from a non-network data source or from a network function at the SMO framework 105 or the non-RT RIC 115. In some examples, the non-RT RIC 115 or the near-RT RIC 125 may be configured to tune RAN behavior or performance. For example, the non-RT RIC 115 may monitor long-term trends and patterns of performance and employ AI / ML models to perform corrective actions through the SMO framework 105 (such as via reconfiguration of O1) or via the creation of RAN management policies (such as A1 policies).

[0046] At least one of the CU 110, the DU 130, and the RU 140 may be referred to as a base station 102. Therefore, the base station 102 may include one or more of the CU 110, the DU 130, and the RU 140 (each component is indicated by a dotted line to indicate that each component may be included in the base station 102 or may not be included in the base station). The base station 102 provides an access point to the core network 120 for the UE 104. The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). Small cells include femto cells, pico cells, and micro cells. A network including both small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include a home evolved Node B (eNB) (HeNB), which may provide services to a restricted group referred to as a closed subscriber group (CSG). The communication link between RU 140 and UE 104 may include uplink (UL) (also known as reverse link) transmission from UE 104 to RU 140 and / or downlink (DL) (also known as forward link) transmission from RU 140 to UE 104. The communication link may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming and / or transmit diversity. The communication link may be through one or more carriers. For each carrier allocated in a carrier aggregation of up to YxMHz (x component carriers) for transmission in each direction, the base station 102 / UE 104 may use a spectrum of up to YMHz (e.g., 5MHz, 10MHz, 15MHz, 20MHz, 100MHz, 400MHz, etc.) bandwidth. These carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated to DL than to UL). Component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

[0047] Some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL wireless wide area network (WWAN) spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). The D2D communication may be through a variety of wireless D2D communication systems, such as, for example, Bluetooth, Wi-Fi based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, LTE, or NR.

[0048] The wireless communication system may also include a Wi-Fi AP 150 that communicates with a UE 104 (also referred to as a Wi-Fi station (STA)) via a communication link 154, for example, in a 5 GHz unlicensed spectrum, etc. When communicating in an unlicensed spectrum, the UE 104 / AP 150 may perform a clear channel assessment (CCA) to determine whether a channel is available prior to communication.

[0049] The electromagnetic spectrum is typically subdivided into various categories, bands, channels, etc. based on frequency / wavelength. In 5G NR, two initial operating bands have been identified as frequency range designations FR1 (410 MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz). Although a portion of FR1 is greater than 6 GHz, FR1 is often referred to (interchangeably) as the "sub-6 GHz" band in various documents and articles. A similar naming issue sometimes occurs with respect to FR2, which is often (interchangeably) referred to as the "millimeter wave" band in documents and articles, although different from the extremely high frequency (EHF) band (30 GHz-300 GHz) identified as the "millimeter wave" band by the International Telecommunication Union (ITU).

[0050] Frequencies between FR1 and FR2 are generally referred to as mid-band frequencies. Recent 5G NR research has identified the operating bands for these mid-band frequencies as frequency range designation FR3 (7.125GHz-24.25GHz). The bands falling within FR3 can inherit FR1 characteristics and / or FR2 characteristics, so the features of FR1 and / or FR2 can be effectively extended to mid-band frequencies. In addition, higher frequency bands are currently being explored to extend 5G NR operations to more than 52.6GHz. For example, three higher operating bands have been identified as frequency range designations FR2-2 (52.6GHz-71GHz), FR4 (71GHz-114.25GHz) and FR5 (114.25GHz-300GHz). Each of these higher frequency bands falls within the EHF band.

[0051] In view of the above, unless otherwise specified, if the term "6 GHz or less" is used herein, it may broadly refer to frequencies that may be less than 6 GHz, may be within FR1, or may include mid-band frequencies. In addition, unless otherwise specified, if the term "millimeter wave" is used herein, it may broadly refer to frequencies that may include mid-band frequencies, may be within FR2, FR4, FR2-2, and / or FR5, or may be within the EHF band.

[0052] The base station 102 and the UE 104 may each include multiple antennas (such as antenna elements, antenna panels, and / or antenna arrays) to facilitate beamforming. The base station 102 may send a beamformed signal 182 to the UE 104 in one or more transmit directions. The UE 104 may receive the beamformed signal from the base station 102 in one or more receive directions. The UE 104 may also send a beamformed signal 184 to the base station 102 in one or more transmit directions. The base station 102 may receive the beamformed signal from the UE 104 in one or more receive directions. The base station 102 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of the base station 102 / UE 104. The transmit direction and receive direction of the base station 102 may be the same or may not be the same. The transmit direction and receive direction of the UE 104 may be the same or may not be the same.

[0053] The base station 102 may include and / or be referred to as a gNB, a Node B, an eNB, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit receive point (TRP), a network node, a network entity, a network equipment, or some other suitable term. The base station 102 may be implemented as an integrated access and backhaul (IAB) node, a relay node, a sidelink node, an aggregated (monolithic) base station with a baseband unit (BBU) (including a CU and a DU) and a RU, or as a decomposed base station including one or more of a CU, a DU, and / or a RU. A set of base stations that may include decomposed base stations and / or aggregated base stations may be referred to as a next generation (NG) RAN (NG-RAN).

[0054] The core network 120 may include an access and mobility management function (AMF) 161, a session management function (SMF) 162, a user plane function (UPF) 163, a unified data management (UDM) 164, one or more location servers 168, and other functional entities. AMF 161 is a control node that handles signaling between UE 104 and core network 120. AMF 161 supports registration management, connection management, mobility management, and other functions. SMF 162 supports session management and other functions. UPF 163 supports packet routing, packet forwarding, and other functions. UDM 164 supports the generation of authentication and key agreement (AKA) credentials, user identity handling, access authorization, and subscription management. One or more location servers 168 are illustrated as including a gateway mobile location center (GMLC) 165 and a location management function (LMF) 166. However, in general, the one or more location servers 168 may include one or more location / positioning servers, which may include one or more of the GMLC 165, LMF 166, position determination entity (PDE), serving mobile location center (SMLC), mobile positioning center (MPC), etc. GMLC 165 and LMF 166 support UE location services. GMLC 165 provides an interface for clients / applications (e.g., emergency services) to access UE positioning information. LMF 166 receives measurement and assistance information from NG-RAN and UE 104 via AMF 161 to calculate the location of UE 104. NG-RAN may determine the location of UE 104 using one or more positioning methods. Positioning UE 104 may involve signal measurements, position estimation, and optional speed calculation based on these measurements. Signal measurements may be performed by UE 104 and / or serving base station 102. The measured signals may be based on a satellite positioning system (SPS) 170 (e.g., one or more of a global navigation satellite system (GNSS), a global positioning system (GPS), a non-terrestrial network (NTN), or other satellite positioning / positioning systems), LTE signals, wireless local area network (WLAN) signals, Bluetooth signals, a terrestrial beacon system (TBS), sensor-based information (e.g., an atmospheric pressure sensor, a motion sensor), an NR enhanced cell ID (NR E-CID) method, NR signals (e.g., multi-round trip time (multi-RTT), DL angle of departure (DL-AoD), DL time difference of arrival (DL-TDOA), UL time difference of arrival (UL-TDOA), and UL angle of arrival (UL-AoA) positioning), and / or one or more of other systems / signals / sensors.

[0055] Examples of UE 104 include cellular phones, smart phones, session initiation protocol (SIP) phones, laptops, personal digital assistants (PDAs), satellite radios, global positioning systems, multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, tablet computers, smart devices, wearable devices, vehicles, electric meters, gas pumps, large or small kitchen appliances, healthcare equipment, implants, sensors / actuators, displays, or any other similarly functional devices. Some of the UEs 104 may be referred to as IoT devices (e.g., parking meters, gas pumps, toasters, vehicles, heart monitors, etc.). UE 104 may also be referred to as stations, mobile stations, subscriber stations, mobile units, subscriber units, wireless units, remote units, mobile devices, wireless devices, wireless communication devices, remote devices, mobile subscriber stations, access terminals, mobile terminals, wireless terminals, remote terminals, mobile phones, user agents, mobile clients, clients, or some other suitable terminology. In some scenarios, the term "UE" may also be applied to one or more supporting devices, such as in a device cluster arrangement. One or more of these devices may access the network collectively and / or individually.

[0056] Reference again Figure 1 In some aspects, the UE 104 may include a TA verification component 198 configured to: send an indication of a first measurement for at least one DL-RS associated with a first cell at a first time instance, wherein the first cell is included in a set of cells of an L1 mobility configuration or a set of cells of an L2 mobility configuration; receive an estimated TA associated with the first cell at a second time instance after the first time instance; perform a second measurement on the at least one DL-RS; and accept or reject the estimated TA for communication with the first cell based on at least one of the first measurement or the second measurement. In some aspects, the base station 102 may include a TA component 199 configured to: receive an indication of a first measurement for at least one DL-RS associated with a first cell at a first time instance, wherein the first cell is included in a set of cells of an L1 mobility configuration or a set of cells of an L2 mobility configuration; estimate a TA associated with the first cell based on the first measurement for the at least one DL-RS; and send the estimated TA associated with the first cell at a second time instance after the first time instance. Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar areas such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0057] Figure 2A FIG200 is a diagram illustrating an example of a first subframe within a 5G NR frame structure. Figure 2B FIG230 is a diagram illustrating an example of DL channels within a 5G NR subframe. Figure 2C FIG250 is a diagram illustrating an example of a second subframe within a 5G NR frame structure. Figure 2D FIG280 is a diagram illustrating an example of UL channels within a 5G NR subframe. The 5G NR frame structure may be frequency division duplex (FDD) (wherein for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to either DL or UL), or may be time division duplex (TDD) (wherein for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to both DL and UL). Figure 2A , Figure 2C In the example provided, the 5G NR frame structure is assumed to be TDD, where subframe 4 is configured with slot format 28 (most of which are DL), where D is DL, U is UL, and F is flexible between DL / UL, and subframe 3 is configured with slot format 1 (all of which are UL). Although subframes 3 and 4 are shown as having slot formats 1 and 28, respectively, any particular subframe may be configured with any of the various available slot formats 0-61. Slot formats 0 and 1 are full DL and full UL, respectively. Other slot formats 2-61 include a mix of DL, UL and flexible symbols. The UE is configured with the slot format (dynamically configured through DL control information (DCI) or semi-statically / statically configured through radio resource control (RRC) signaling) via the received slot format indicator (SFI). Note that the following description also applies to the 5G NR frame structure as TDD.

[0058] FIG. 2A to FIG. 2DThe frame structure is illustrated, and various aspects of the present disclosure may be applicable to other wireless communication technologies that may have different frame structures and / or different channels. A frame (10ms) may be divided into 10 equally sized subframes (1ms). Each subframe may include one or more time slots. A subframe may also include a microslot, which may include 7, 4, or 2 symbols. Each time slot may include 14 or 12 symbols, depending on whether the cyclic prefix (CP) is normal or extended. For a normal CP, each time slot may include 14 symbols, and for an extended CP, each time slot may include 12 symbols. The symbol on the DL may be a CP orthogonal frequency division multiplexing (OFDM) (CP-OFDM) symbol. The symbol on the UL may be a CP-OFDM symbol (for high throughput scenarios) or a discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbol (also known as a single carrier frequency division multiple access (SC-FDMA) symbol) (for power-limited scenarios; limited to single-stream transmission). The number of time slots within a subframe is based on the CP and parameter set. The numerology defines the subcarrier spacing (SCS) (see Table 1). The symbol length / duration can be scaled with 1 / SCS.

[0059]

[0060] Table 1: Parameter set, SCS and CP

[0061] For normal CP (14 symbols / slot), different parameter sets μ0 to 4 allow 1, 2, 4, 8, and 16 slots per subframe, respectively. For extended CP, parameter set 2 allows 4 slots per subframe. Thus, for normal CP and parameter set μ, there are 14 symbols / slot and 2 μ timeslots / subframe. The subcarrier spacing can be equal to 2 μ *15kHz, where μ is parameter set 0 to 4. Therefore, the subcarrier spacing for parameter set μ=0 is 15kHz, and the subcarrier spacing for parameter set μ=4 is 240kHz. The symbol length / duration is inversely related to the subcarrier spacing. FIG. 2A to FIG. 2D An example of a parameter set μ=2 with a normal CP of 14 symbols per slot and 4 slots per subframe is provided. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is about 16.67 μs. Within a frame set, there may be one or more different bandwidth parts (BWPs) that are frequency-division multiplexed (see Figure 2B ). Each BWP may have a specific parameter set and CP (normal or extended).

[0062] A resource grid may be used to represent the frame structure. Each slot includes a resource block (RB) (also referred to as a physical RB (PRB)) extending over 12 consecutive subcarriers. The resource grid is divided into a plurality of resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0063] like Figure 2A As illustrated, some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include a demodulation RS (DM-RS) (indicated as R for a particular configuration, but other DM-RS configurations are possible) and a channel state information reference signal (CSI-RS) for channel estimation at the UE. The RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and a phase tracking RS (PT-RS).

[0064] Figure 2B Examples of various DL channels within a subframe of a frame are illustrated. A physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs) (e.g., 1, 2, 4, 8, or 16 CCEs), each CCE including six RE groups (REGs), each REG including 12 consecutive REs in an OFDM symbol of an RB. A PDCCH within a BWP may be referred to as a control resource set (CORESET). The UE is configured to monitor PDCCH candidates in a PDCCH search space (e.g., a common search space, a UE-specific search space) during a PDCCH monitoring opportunity on a CORESET, wherein the PDCCH candidates have different DCI formats and different aggregation levels. Additional BWPs may be located at higher and / or lower frequencies on the channel bandwidth. A primary synchronization signal (PSS) may be within symbol 2 of a particular subframe of a frame. The PSS is used by UE 104 to determine subframe / symbol timing and physical layer identification. A secondary synchronization signal (SSS) may be within symbol 4 of a particular subframe of a frame. The SSS is used by the UE to determine the physical layer cell identity group number and the radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine the physical cell identifier (PCI). Based on the PCI, the UE can determine the location of the DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) can be logically grouped with the PSS and SSS to form a synchronization signal (SS) / PBCH block (also referred to as an SS block (SSB)). The MIB provides the number of RBs in the system bandwidth and the system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information not sent via the PBCH (such as a system information block (SIB)), and paging messages.

[0065] like Figure 2CAs illustrated, some of the REs carry DM-RS (indicated as R for a particular configuration, but other DM-RS configurations are possible) for channel estimation at the base station. The UE may send a DM-RS for a physical uplink control channel (PUCCH) and a DM-RS for a physical uplink shared channel (PUSCH). The PUSCH DM-RS may be sent in the first or first two symbols of the PUSCH. Depending on whether a short PUCCH or a long PUCCH is sent and depending on the specific PUCCH format used, the PUCCH DM-RS may be sent in different configurations. The UE may send a sounding reference signal (SRS). The SRS may be sent in the last symbol of a subframe. The SRS may have a comb structure, and the UE may send the SRS on one of the teeth of the comb. The SRS may be used by the base station for channel quality estimation to achieve frequency-dependent scheduling of the UL.

[0066] Figure 2D Examples of various UL channels within a subframe of a frame are illustrated. The PUCCH may be located at a position as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicators (CQI), precoding matrix indicators (PMI), rank indicators (RI), and hybrid automatic repeat request (HARQ) acknowledgement (ACK) (HARQ-ACK) feedback (i.e., one or more HARQ ACK bits indicating one or more ACKs and / or negative ACKs (NACKs)). The PUSCH carries data and may be used to carry, among other things, a buffer status report (BSR), a power headroom report (PHR), and / or UCI.

[0067] Figure 3370 is a block diagram of a base station 310 in an access network communicating with a UE 350. In the DL, Internet Protocol (IP) packets may be provided to a controller / processor 375. The controller / processor 375 implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller / processor 375 provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with delivery of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0068] The transmit (TX) processor 316 and receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1 (which includes the physical (PHY) layer) may include error detection on the transport channel, forward error correction (FEC) coding / decoding of the transport channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 handles the mapping to the signal constellation based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-order phase shift keying (M-PSK), M-order quadrature amplitude modulation (M-QAM)). The decoded and modulated symbols can then be divided into parallel streams. Subsequently, each stream can be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., a pilot) in the time domain and / or frequency domain, and then combined using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially pre-coded to generate multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine the coding and modulation schemes, as well as for spatial processing. Channel estimates may be derived from reference signals and / or channel state feedback sent by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318Tx. Each transmitter 318Tx may modulate a radio frequency (RF) carrier for transmission using a corresponding spatial stream.

[0069] At the UE 350, each receiver 354Rx receives a signal through its corresponding antenna 352. Each receiver 354Rx recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial stream destined for the UE 350. If multiple spatial streams are destined for the UE 350, they can be combined into a single OFDM symbol stream by the RX processor 356. The RX processor 356 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier and the reference signal are recovered and demodulated by determining the most likely signal constellation point sent by the base station 310. These soft decisions can be based on channel estimates calculated by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally sent on the physical channel by base station 310. The data and control signals are then provided to controller / processor 359, which implements layer 3 and layer 2 functionality.

[0070] The controller / processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer readable medium. In the UL, the controller / processor 359 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets. The controller / processor 359 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0071] Similar to the functionality described in conjunction with DL transmissions performed by the base station 310, the controller / processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0072] Channel estimates derived by the channel estimator 358 based on a reference signal or feedback sent by the base station 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via separate transmitters 354Tx. Each transmitter 354Tx may modulate an RF carrier with a corresponding spatial stream for transmission.

[0073] UL transmissions are processed at the base station 310 in a manner similar to that described in conjunction with the receiver functionality at the UE 350. Each receiver 318Rx receives a signal through its respective antenna 320. Each receiver 318Rx recovers information modulated onto an RF carrier and provides the information to the RX processor 370.

[0074] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer readable medium. In the UL, the controller / processor 375 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, control signal processing to recover IP packets. The controller / processor 375 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0075] At least one of the TX processor 368, the RX processor 356, and the controller / processor 359 may be configured to perform operations related to Figure 1 The TA verification component 198 combines various aspects.

[0076] At least one of the TX processor 316, the RX processor 370, and the controller / processor 375 may be configured to perform operations related to Figure 1 The TA component 199 combines various aspects.

[0077] Figure 4 400 is a diagram illustrating an example of dual connectivity and carrier aggregation (CA). A UE 402 may be connected to a master cell group (MCG) 404 and a secondary cell group (SCG) 406. Such an arrangement may be referred to as dual connectivity (DC) 408. MCG 404 may be a group of serving cells associated with a master node having a control plane connection to a core network (e.g., core network 120). The master node may be a base station such as a gNB, eNB, etc. (i.e., a network entity). SCG 406 may be a group of serving cells associated with a secondary node that does not have a control plane connection to the core network. The secondary node may be a base station such as a gNB, eNB, etc. (i.e., a network entity). Based on various factors (such as the location of UE 402, network status, etc.), MCG 404 may become SCG 406, and SCG 406 may become MCG 404.

[0078] The MCG 404 includes a PCell 410. The MCG 404 may also include one or more SCells (e.g., a first SCell 412 and a second NSCell 414, where N is a positive integer greater than one). The PCell 410, the first SCell 412, and / or the second NSCell 414 may be in a CA 416 configuration. In some aspects, based on various factors such as the location of the UE 402, network status, etc., a primary cell may become a secondary cell, or a secondary cell may become a primary cell.

[0079] The SCG 406 includes a primary secondary cell (PSCell) 418. The PSCell 418 is the primary cell of the SCG 406. The SCG 406 may also include one or more SCells (e.g., a first SCell 420 and an Mth SCell 422, where M is a positive integer greater than one). The PSCell 418, the first SCell 420, and / or the Mth SCell 422 may be in a CA configuration 424. In some aspects, based on various factors (such as the location of the UE 402, network status, etc.), the primary secondary cell may become a secondary cell, or the secondary cell may become a primary secondary cell.

[0080] The PCell 410 of the MCG 404 and the PSCell 418 of the SCG 406 may be referred to as a special cell (SpCell) 426. For dual connectivity operations, the term SpCell refers to the PCell of the MCG or the PSCell of the SCG, for example, depending on whether the MAC entity is associated to the MCG or the SCG, respectively. The SpCell supports PUCCH transmission and contention-based random access and is always activated. The SpCell 426 is responsible for data and control functionality. In the absence of a DC (for example, when the MCG 404 is configured and when the SCG 406 is not configured), the PCell 410 may be referred to as the SpCell 426. The cell group including the SpCell 426 may be referred to as a PCG. It should be understood that the SpCell may change based on various factors (such as the location of the UE 402, the network status, etc.). In an example, the network entity may configure the first SCell 412 as a primary cell and the M SCell 422 as a primary secondary cell to configure a new SpCell.

[0081] Figure 5 500 is a diagram illustrating an example TAG for cell synchronization. A base station 504 (e.g., via a DU 506) may configure a L1 / L2 mobility configured cell set 508 for a UE 502. The term "L1 / L2 mobility configured cell set" may refer to a cell set configured for a UE such that cells in the cell set may be updated by a base station (e.g., a gNB) using L1 or L2 signaling to become SpCells. L1 signaling may refer to DCI. L2 signaling may refer to a medium access control (MAC) control element (MAC-CE). Cells within the L1 / L2 mobility configured cell set 508 (represented as circles in the diagram 500) may belong to the same or different TAGs. Each TAG may be associated with a different TA. The term "TA" may refer to a command transmitted by a base station to a UE to adjust an uplink transmission of the UE such that the UE transmits UL symbols in advance according to a command for transmission (such as PUSCH, PUCCH, and / or SRS transmission). UE 502 may apply a TA associated with a TAG to uplink communications via / with cells belonging to the TAG / through uplink communications with cells belonging to the TAG. TA may refer to a negative offset between the start of a DL time slot and the start of a UL time slot observed by UE 502 at UE 502. The TA may take into account propagation delays so that the UL transmission and DL transmission of the UE are aligned at a reference point. Typically, a first UE located relatively far from a base station may start UL transmission relatively faster than a second UE located relatively close to the base station. Therefore, the first UE may apply a larger TA to the UL transmission than the TA applied by the second UE.

[0082] A TAG that includes a PCell (or SpCell) may be referred to as a primary TAG (pTAG). A TAG that includes an SCell (rather than a PCell or SpCell) may be referred to as a secondary TAG (sTAG). Diagram 500 depicts cells belonging to a pTAG, cells belonging to sTAG1, and cells belonging to sTAG2. When an SCell is added to a cell set 508 of an L1 / L2 mobility configuration, the base station 504 may associate the SCell to the TAG. The initial TAG assignment may be determined by the base station 504 (i.e., the serving gNB). The base station 504 may determine the initial TAG assignment based on the operating band, the presence of a repeater, the location of the cell, and / or the location of the UE 502.

[0083] To establish the initial timing, the UE 502 may perform a RACH process with the pTAG, that is, the UE 502 may perform the RACH process with the SpCell (or PCell). The UE may obtain the TA associated with the pTAG upon completing the RACH process. To further establish the initial timing, the UE 502 may perform a RACH process with the SCell belonging to the sTAG. For example, the UE 502 may receive a PDCCH command from a base station associated with the SCell. The UE 502 may perform a non-contention RACH process upon receiving the PDCCH command. The UE 502 may obtain the TA associated with the sTAG upon completing the non-contention RACH process.

[0084] The cells (or cell groups) within the L1 / L2 mobility configured cell set 508 may be activated or deactivated by the base station 504 via L1 / L2 signaling. The activated cells / cell groups within the L1 / L2 mobility configured cell set 508 may be used by the UE 502 for data transfer and control. In an example, when the UE 502 is in a first position, cells in pTAG and sTAG1 may be activated. When the UE 502 moves to a second position, the base station 504 may send L1 / L2 signaling to activate / deactivate the cells / cell groups. In an example, the L1 / L2 signaling sent by the base station 504 when the UE 502 is in the second position may activate cells in sTAG2.

[0085] For L1 / L2 inter-cell mobility, when a cell / cell group is activated, UE 502 may obtain a TA for the cell / cell group. Obtaining a TA for the activated cell in a relatively fast manner may help improve the communication reliability at UE 502. UE 502 may receive frequent updates of the TA for the activated cell / cell group. However, compared with the TA for the activated cell / cell group, the TA for the deactivated cell / cell group may not be the latest. In an example, UE 502 may send a report (e.g., an L1 report) to base station 504, which includes a DL timing difference between a reference cell and a deactivated cell. Base station 504 may calculate an estimated TA for the deactivated cell based on the DL timing difference. Due to the lack of active communication between UE 502 and the deactivated cell, the estimated TA for the deactivated cell may be inaccurate. Due to the TA estimation error based on the DL timing difference included in the report, the estimated TA for the deactivated cell may also be inaccurate. UE 502 may obtain an accurate TA for a deactivated cell by performing a RACH procedure commanded by a PDCCH command; however, the RACH procedure may be time consuming.

[0086] Figure 6 600 is an example of a UE 602 calculating a DL timing difference and receiving a TA. The UE 602 may perform a validation on the TA obtained from a base station (e.g., a gNB) before applying the TA. The validation may be based on the quality of service (QoS) of the service traffic. The validation may also be based on a maximum transmit timing deviation tolerance (which may be referred to as "Te") of the UE 602. In an example, the maximum transmit timing deviation tolerance may be 3 μs.

[0087] The UE 602 may perform reference signal received power (RSRP) measurements on downlink reference signals (DL-RS) transmitted by the first deactivated cell 606, the SpCell 604 of the UE 602, and the second deactivated cell 608. The UE 602 may also calculate the DL timing difference (relative to the reference cell) of the first deactivated cell 606, the SpCell 604, and the second deactivated cell 608 based on the DL-RS.

[0088] In an example, the UE 602 may receive a DL-RS from a first deactivated cell 606, and at time t1, the UE 602 may measure a DL timing difference relative to a reference cell and report the DL timing difference to the SpCell 604. At time t2 occurring after time t1, the UE 602 may receive an estimated TA (referred to as "TA information" in Figure 600) from the SpCell 604, wherein the estimated TA is used for communication via / with / through the first deactivated cell 606. In an example, the first deactivated cell 606 may be a cell to be activated. However, the UE 602 may have changed position between time t1 and time t2. The estimated TA may be based on the DL timing difference reported at time t1. If the difference between time t2 and time t1 is greater than a threshold, the estimated TA may be inaccurate for communication via / with / through the first deactivated cell 606. In other words, the strength of the channel associated with the first deactivated cell 606 may have changed by more than a threshold amount between time t1 and time t2. In addition, the UE 602 may not report (i.e., RSRP report) at a frequency that enables the SpCell 604 to accurately estimate the TA. Additionally, if the UE 602 does not apply the estimated TA within a threshold period of time after receiving the estimated TA, the estimated TA may be inaccurate due to the mobility of the UE 602.

[0089] In a wireless communication system, the network may aim to ensure that the UE maintains connectivity with a network entity (e.g., a base station) when the UE moves within the network. Inter-cell mobility based on L1 / L2 may help reduce mobility latency. For example, the configuration and maintenance of multiple candidate cells may allow for rapid application of configurations for candidate cells. In addition, a dynamic switching mechanism between candidate serving cells (including SpCells and SCells) based on L1 / L2 signaling may further reduce latency.

[0090] Inter-cell mobility based on L1 / L2 is applicable to independent operation scenarios, CA scenarios, and DC (e.g., NR-DC) scenarios. In independent operation scenarios and CA scenarios, inter-cell mobility based on L1 / L2 is applicable to intra-DU situations and / or intra-CU inter-DU situations. Inter-cell mobility based on L1 / L2 is applicable to both FR1 and FR2 and both co-frequency and hetero-frequency. In inter-cell mobility based on L1 / L2, the source cell and the target cell can be synchronized or asynchronous.

[0091] The UE may apply the TA to UL transmissions with a cell to take into account the propagation delay between the UE and the cell. When the UE receives signaling from the network for connecting to a cell to be activated in a set of cells configured for L1 / L2 mobility, the network may provide the UE with an estimated TA, wherein the estimated TA may be based on a measurement report sent by the UE to the network. However, the estimated TA may be inaccurate for various reasons. In one example, the channel strength may have changed between the time when the UE last sent a measurement report and the time when the estimated TA was obtained, which may cause the estimated TA to be inaccurate. In another example, the UE may not send measurement reports frequently enough to enable the network to accurately generate the estimated TA. In yet another example, the estimated TA may be inaccurate due to UE mobility, that is, the time when the UE applies the estimated TA may be too far away from the time when the network generates the estimated TA. Applying an inaccurate TA to UL transmissions may affect communication reliability.

[0092] Various techniques for UE-side TA verification are described herein, which may utilize RSRP measurements to represent channel strength. In an example, a UE sends an indication of a first measurement for at least one DL-RS associated with a first cell at a first time instance, wherein the first cell is included in a set of cells configured for L1 mobility or a set of cells configured for L2 mobility. The UE receives an estimated TA associated with the first cell at a second time instance after the first time instance. The UE performs a second measurement on the at least one DL-RS. The UE accepts or rejects the estimated TA for communication with the first cell based on at least one of the first measurement or the second measurement. Via the above-mentioned TA verification process, the UE may be able to reject an inaccurate TA. Therefore, the TA verification process may result in improved communication reliability.

[0093] Figure 7 700 is a diagram illustrating an example of UE-side TA verification. The UE-side TA verification may be based on RSRP measurements performed on DL-RS. UE 702 may utilize filtered (e.g., averaged) RSRP measurements to represent channel strength. The channel strength may be associated with the location of UE 702. For example, as the location of UE 702 changes, the TA of UE 702 for communication via / with / through a cell may change. In addition, as the location of UE 702 changes, RSRP measurements performed on a DL-RS associated with the cell may also change. In general, UE 702 may determine TA changes using changes in RSRP measurements.

[0094] UE 702 may be configured with an RSRP change threshold via RRC signaling. Each cell in a set of cells configured for L1 / L2 mobility (e.g., a set of cells configured for L1 / L2 mobility 508) may be configured with a unique threshold (or the same threshold). At time t1, UE 702 may send an L1 report to SpCell 704. The L1 report may include a downlink timing difference calculated by UE 702 relative to a reference cell. UE 702 may calculate the DL timing difference based on a DL-RS sent by a deactivated cell 706 in a set of cells configured for L1 / L2 mobility (e.g., a set of cells configured for L1 / L2 mobility 508). The L1 report may also include a first RSRP measurement performed by UE 702 on the DL-RS of the deactivated cell 706.

[0095] At time t2 occurring after time t1, UE 702 may receive an estimated TA from SpCell 704, wherein the estimated TA may be based on the DL timing difference. In an example, UE 702 has changed position between time t1 and time t2. Therefore, deactivated cell 706 may be activated at a time occurring after time t2. The estimated TA may be used for communication of UE 702 via deactivated cell 706 (to be activated) / communication with the deactivated cell / communication through the deactivated cell. SpCell 704 may estimate the estimated TA based on the DL timing difference. Upon receiving the estimated TA, UE 702 may perform a second RSRP measurement on the DL-RS sent by deactivated cell 706. UE 702 may determine the RSRP change between time t1 and time t2. For example, UE 702 may compare the absolute value of the difference between the first RSRP measurement at time t1 and the second RSRP measurement at time t2 with a threshold. The threshold may be unique to the deactivated cell 706 or may be shared by several cells. If the RSRP change is less than the threshold, the UE 702 may accept the estimated TA for communication via / with / through the (to be activated) deactivated cell 706. If the RSRP change is greater than or equal to the threshold, the UE 702 may reject the estimated TA.

[0096] Figure 8800 is a diagram illustrating an example communication between a UE 802 and a base station 804. The communication may be used to verify the TA. The base station 804 may be associated with the current SpCell of the UE 802. At 806, the UE 802 may receive an L1 / L2 mobility configuration sent by the base station 804. In the example, the L1 / L2 mobility configuration may configure a cell set 508 of the L1 / L2 mobility configuration. At 808, the UE 802 may receive an RSRP change threshold for the cell via RRC signaling. The RRC signaling may configure each of these cells with a separate change threshold. At 809, the UE 802 may send a confirmation to the base station 804, wherein the confirmation may indicate that the RRC configuration / reconfiguration is complete.

[0097] At 810, UE 802 may perform a first measurement on a DL-RS associated with a cell at a first point in time. In an example, the cell may be a currently deactivated cell in the set of cells 508 of the L1 / L2 mobility configuration. The first measurement may include a DL timing difference of the cell relative to a reference cell. The first measurement may also include an RSRP measurement performed on the DL-RS. The RSRP measurement may be an average RSRP measurement.

[0098] At 812, UE 802 may send the first measurement to base station 804. At 814, base station 804 may estimate the TA for the cell based on the DL timing difference sent at 812. At 816, UE 802 may receive the estimated TA from base station 804. At 818, UE 802 may perform a second measurement on the DL-RS associated with the cell at a second time point occurring after the first time point. The second measurement may include an RSRP measurement. The RSRP measurement may be an average RSRP measurement. At 820, UE 802 may accept or reject the estimated TA for communication via / with / through the cell based on at least one of the first measurement or the second measurement. In an example, UE 802 may calculate the difference between the first RSRP measurement performed by UE 802 at 810 and the second RSRP measurement performed by UE 802 at 818. If the difference is greater than a threshold, UE 802 may reject the estimated TA. If the difference is less than the threshold, the UE 802 may accept the estimated TA. In one aspect, the UE may calculate the absolute value of the difference before comparing the difference to the threshold. As described above, the threshold may be specific to the cell and may be configured via RRC signaling. If the UE 802 accepts the estimated TA, the UE 802 may communicate via / with / through the cell using the estimated TA.

[0099] Fig. 9900 is a diagram illustrating an example communication between a UE 902, a SpCell 904, and a cell to be activated 906. The cell to be activated 906 may act as a SpCell when activated, or may act as an SCell when activated. At 908, the UE 902 may receive a new cell activation command for the cell to be activated 906 from the SpCell 904. In an example, the SpCell 904 may be associated with the base station 804 described above in the description of the diagram 800. The new cell activation command may include an estimated TA for the cell to be activated 906. In an example, 908 may correspond to 816 described above in the description of the diagram 800. The new cell activation command may indicate that the UE 902 will confirm the new cell activation command. At 910, the UE 902 may perform TA verification based on the estimated TA included in the new cell activation command. In an example, 910 may correspond to 820 (as well as 810 and 818 ) described above in the description of diagram 800 .

[0100] In an example, the UE 902 may determine that the estimated TA is invalid for communication via / with / through the cell to be activated 906 (e.g., based on RSRP change measurements). At 912, the UE 902 may send a TA invalid notification to the SpCell 904. The TA invalid notification may indicate that the estimated TA has been rejected for communication with the cell to be activated 906. In one aspect, the TA invalid notification is sent via a medium access control (MAC) control element (MAC-CE) (such as a dedicated MAC-CE). In another aspect, the TA invalid notification is sent via uplink control information (UCI) (such as a dedicated UCI). In yet another aspect, the UE 902 may bundle the TA invalid notification with an acknowledgement / negative acknowledgement (ACK / NACK) message for the new cell activation command received at 908. For example, the UE 902 may delay acknowledging the new cell activation command until after TA verification is performed at 910.

[0101] In one aspect, at 914A, the UE 902 may receive a PDCCH command from the SpCell 904, the PDCCH command instructing the UE 902 to initiate a RACH procedure with the cell to be activated 906. The SpCell 904 may send the PDCCH command based on receiving the TA invalidation notification sent by the UE 902 at 912. On the other hand, at 914B, the UE 902 may receive a PDCCH command from the cell to be activated 906, the PDCCH command instructing the UE 902 to initiate a RACH procedure with the cell to be activated 906. In an example, a base station associated with the SpCell 904 (e.g., the base station 804) may communicate with a base station associated with the cell to be activated 906 so that the cell to be activated 906 sends the PDCCH command received by the UE 902 at 914B. At 916, in the case where the cell to be activated 906 will serve as a new SpCell, the UE 902 may initiate a RACH procedure with the cell to be activated 906. The UE 902 may obtain, via the RACH procedure, a correct TA for the cell to be activated 906. When the cell to be activated 906 is activated, the UE 902 may communicate via / with / through the (now activated) cell to be activated 906 via the correct TA.

[0102] Fig.101000 is a diagram illustrating an example communication between a UE 1002, a SpCell 1004, and a cell to be activated 1006. The cell to be activated 1006 may act as a SpCell when activated, or may act as an SCell when activated. At 1008, the UE 1002 may receive a new cell activation command for the cell to be activated 1006 from the SpCell 1004. In an example, the SpCell 1004 may be associated with the base station 804 described above in the description of the diagram 800. The new cell activation command may include an estimated TA for the cell to be activated 1006. In an example, 1008 may correspond to 816 described above in the description of the diagram 800. The new cell activation command may indicate that the UE 1002 will confirm the new cell activation command. At 1010, the UE 902 may perform TA verification based on the estimated TA included in the new cell activation command. In an example, 1010 may correspond to 820 (and 810 and 818) described above in the description of diagram 800. For example, UE 1002 may perform a first measurement on a DL-RS associated with a cell to be activated 1006, wherein the first measurement may include a DL timing difference and / or RSRP measurement of the cell to be activated 1006 relative to a reference cell. UE 1002 may send the first measurement to SpCell 1004, and receive an estimated TA from SpCell 1004 based on the DL timing difference.

[0103] In an example, the UE 1002 may determine that the estimated TA is invalid for communication via / with / through the cell to be activated 1006 (e.g., based on RSRP change measurement). At 1011, the UE 1002 may perform another measurement on the DL-RS associated with the SpCell 1004. Such measurements may include DL timing differences and / or RSRP measurements relative to a reference cell. At 1012, the UE 902 may send a TA invalidation notification. The TA invalidation notification may indicate that the estimated TA has been rejected for communication with the cell to be activated 1006. The TA invalidation notification may also include UL synchronization assistance information (referred to herein as "UL synchronization assistance information"). The UL synchronization assistance information may include the latest DL timing difference of the cell to be activated 1006 relative to the reference cell (i.e., the DL timing difference measured at 1011). In one aspect, the TA invalidation notification is sent via a MAC-CE (such as a dedicated MAC-CE). On the other hand, the TA invalidation notification is sent via a UCI (such as a dedicated UCI). In yet another aspect, the UE 1002 may bundle the TA invalidation notification with an ACK / NACK message for the new cell activation command received at 1008. For example, the UE 1002 may delay acknowledging the new cell activation command until after performing TA verification at 1010.

[0104] At 1014, the SpCell 1004 may estimate a new TA for communication via / with / through the cell to be activated 1006 based on the UL synchronization assistance information. At 1016, the UE 1002 may receive the estimated new TA from the SpCell 1004. In one aspect, the UE 1002 may receive the estimated new TA via a MAC-CE. In another aspect, the UE 1002 may receive the estimated new TA via a DCI. If the UE 1002 rejects the estimated new TA, the UE 1002 may also receive an indication of RACH resources used in the RACH process.

[0105] At 1018, UE 1002 may perform TA verification based on the estimated new TA. In an example, 1018 may correspond to 1010 (and 818 / 820), where the estimated new TA is used to replace the (previously) estimated TA. For example, when UE 1002 receives the estimated new TA, UE 1002 may perform RSRP measurement on the DL-RS associated with SpCell 1004. UE 1002 may accept or reject the estimated TA based on the RSRP measurement, the RSRP measurement performed at 1011, and a threshold similar to UE 802 at 820. In an example, UE 1002 may determine that the estimated new TA is invalid for communication via / with / through the cell to be activated 1006 (e.g., based on RSRP change measurement). At 1020, UE 1002 may determine whether the maximum number of TA rejections has occurred. In an example, the UE 1002 may receive an indication of the maximum number of TA rejections during the RRC configuration that occurred at 808 in diagram 800. If the maximum number of TA rejections has not occurred, the UE 1002 may repeat 1012 with updated UL synchronization assistance information. If the maximum number of TA rejections has occurred, at 1024, the UE 1002 may initiate a RACH procedure with the to-be-activated cell 1006, in the event that the to-be-activated cell 1006 will serve as a new SpCell. The UE 1002 may utilize the RACH resources received at 1016 for the RACH procedure. The UE 1002 may obtain the correct TA for the to-be-activated cell 1006 via the RACH procedure. When the to-be-activated cell 1006 is activated, the UE 902 may communicate via / with / through the (now activated) to-be-activated cell 1006 via the correct TA.

[0106] Fig.111100 is a flow chart of a method of wireless communication. The method may be performed by a UE (e.g., UE 104, UE 350, UE 702, UE 802, UE 902, UE 1002, device 1504, etc.). The method may be performed by a TA verification component 198. The method may be associated with various technical advantages at the UE, such as improving communication reliability via an accurate TA.

[0107] At 1102, the UE sends an indication of a first measurement of at least one DL-RS associated with a first cell at a first time instance, wherein the first cell is included in a set of cells configured for L1 mobility or a set of cells configured for L2 mobility. Figure 8 At 812, UE 802 is shown sending a first measurement. In an example, Figure 7 The first measurement is performed on the DL-RS associated with the deactivated cell 706 in the UE. In another example, the first measurement may include a DL timing difference relative to a reference cell at time t1, such as Figure 6 In another example, the first measurement may also include an RSRP measurement performed at time t1, such as Figure 7 In yet another example, the first cell may be included in Figure 5 The illustrated L1 / L2 mobility configured cell set 508. For example, 1102 can be performed by the TA verification component 198.

[0108] At 1104, the UE receives an estimated TA associated with the first cell at a second time instance after the first time instance. Figure 8 UE 802 is shown receiving the estimated TA at 816. In an example, the first cell may be Figure 7 1104 can be performed by the TA verification component 198, for example.

[0109] At 1106, the UE performs a second measurement on the at least one DL-RS. For example, Figure 8 At 818, UE 802 performs a second measurement on the DL-RS. In another example, the second measurement may include an RSRP measurement performed at time t2, such as Figure 7 For example, 1106 can be performed by the TA verification component 198.

[0110] At 1108, the UE accepts or rejects the estimated TA for communication with the first cell based on at least one of the first measurement or the second measurement. Figure 8UE 802 accepting or rejecting the estimated TA for communication with the cell based on at least one of the first measurement or the second measurement is shown at 820. For example, 1108 can be performed by TA verification component 198.

[0111] Fig.12 1200 is a flow chart of a method of wireless communication. The method may be performed by a UE (e.g., UE 104, UE 350, UE 702, UE 802, UE 902, UE 1002, device 1504, etc.). The method (including various aspects described below) may be performed by a TA verification component 198. The method may be associated with various technical advantages at the UE, such as improving communication reliability via accurate TA.

[0112] At 1204, the UE sends an indication of a first measurement of at least one DL-RS associated with a first cell at a first time instance, wherein the first cell is included in a set of cells configured for L1 mobility or a set of cells configured for L2 mobility. Figure 8 At 812, UE 802 is shown sending a first measurement. In an example, Figure 7 The first measurement is performed on the DL-RS associated with the deactivated cell 706 in the UE. In another example, the first measurement may include a DL timing difference relative to a reference cell at time t1, such as Figure 6 In another example, the first measurement may also include an RSRP measurement performed at time t1, such as Figure 7 In yet another example, the first cell may be included in Figure 5 The illustrated L1 / L2 mobility configured cell set 508. For example, 1204 can be performed by the TA verification component 198.

[0113] At 1206, the UE receives an estimated TA associated with the first cell at a second time instance after the first time instance. Figure 8 UE 802 is shown receiving the estimated TA at 816. In an example, the first cell may be Figure 7 1206 can be performed by the TA verification component 198, for example.

[0114] At 1208, the UE performs a second measurement on the at least one DL-RS. For example, Figure 8 At 818, UE 802 performs a second measurement on the DL-RS. In another example, the second measurement may include an RSRP measurement performed at time t2, such as Figure 7 For example, 1208 can be performed by the TA verification component 198.

[0115] At 1210, the UE accepts or rejects the estimated TA for communication with the first cell based on at least one of the first measurement or the second measurement. Figure 8 The UE 802 accepts or rejects the estimated TA for communication with the cell based on at least one of the first measurement or the second measurement at 820. For example, 1210 can be performed by the TA verification component 198.

[0116] In one aspect, the estimated TA may be accepted or rejected based further on at least one of: a difference between the first measurement and the second measurement; or an RSRP threshold of the first cell associated with the second measurement. Figure 7 The threshold and the difference between the RSRP measurement performed at time t1 and the RSRP measurement performed at time t2 are shown.

[0117] In one aspect, at 1202, the UE may perform the first measurement on the at least one DL-RS before the first time instance, wherein the indication of the first measurement may be sent based on the performed first measurement. Figure 8 UE 802 is shown performing a first measurement on a DL-RS associated with a cell at 810. For example, 1202 can be performed by TA verification component 198.

[0118] In one aspect, the first cell may be a deactivated cell in the cell set of the L1 mobility configuration or the cell set of the L2 mobility configuration, wherein the second cell may serve as the SpCell before accepting or rejecting the estimated TA. Figure 7 , the first cell may be a deactivated cell 706, and the second cell may be a SpCell 704. In another example, the first cell and the second cell may be Figure 5 The cell set 508 of the illustrated L1 / L2 mobility configuration.

[0119] In one aspect, the first measurement may be a DL timing difference measurement between the first cell and a reference cell, and the second measurement may be an RSRP measurement. Figure 6 UE 602 is shown measuring the DL timing difference relative to a reference cell. In another example, Figure 7 UE 702 is shown performing RSRP measurements at time t2.

[0120] In one aspect, at 1212, the UE may send a notification indicating that the estimated TA is rejected, wherein the notification may be sent if the estimated TA is rejected for the communication with the first cell. Fig. 9At 912, the UE 902 is shown sending a TA invalidation notification indicating that the estimated TA has been rejected for communication with the cell to be activated 906. For example, Fig.10 At 1012, the UE 1002 is shown sending a TA invalidation notification indicating that the estimated TA has been rejected for communication with the cell to be activated 1006. For example, 1212 can be performed by the TA verification component 198.

[0121] In one aspect, the notification may be sent via MAC-CE or UCI. Fig. 9 The TA invalid notification may be sent via MAC-CE or UCI as shown at 912. For example, Fig.10 At 1012, it is shown that the TA invalid notification can be sent via MAC-CE or UCI.

[0122] In one aspect, the notification may be associated with an ACK or a NACK. Fig. 9 The TA invalidation notification may be associated with an ACK / NACK message as shown at 912. For example, Fig.10 It is shown at 1012 that the TA invalid notification can be associated with an ACK / NACK message.

[0123] In one aspect, at 1214, the UE may receive a PDCCH order after sending the notification. For example, Fig. 9 At 914A, UE 902 is shown receiving a PDCCH commanding a RACH process from SpCell 904. In another example, Fig. 9 At 914B, UE 902 is shown receiving a PDCCH commanding a RACH process from cell to be activated 906. For example, 1214 can be performed by TA verification component 198.

[0124] In one aspect, at 1216, the UE may initiate a RACH process with the first cell based on the PDCCH command. For example, Fig. 9 At 916, UE 902 is shown initiating a RACH procedure with cell to be activated 906. For example, 1216 can be performed by TA verification component 198.

[0125] In one aspect, the RACH process with the first cell may be initiated in the case where the first cell will act as a SpCell. Fig. 9 At 916 it is shown that the RACH process may be initiated in the event that the cell to be activated 906 is to be a new SpCell.

[0126] In one aspect, at 1218, the UE may perform a third measurement between the first cell and the reference cell at a third time instance after the second time instance, wherein the third measurement may be performed after sending the notification, and wherein the third measurement may be a DL timing difference measurement. For example, Fig.10 At 1011, it is shown that UE 1002 may perform measurements after the TA verification at 1010, and the measurements may include DL timing difference measurements. The third measurement may be as follows Figure 7 The illustrated DL timing difference measurement 1218 can be performed by the TA verification component 198, for example.

[0127] In one aspect, at 1220, the UE may send an indication of the third measurement via MAC-CE or UCI. For example, Fig.10 At 1012, the UE 1002 is shown to send a TA invalid notification via MAC-CE or UCI, where the TA invalid notification may include UL synchronization assistance information. The UL synchronization assistance information may include the third measurement. In another example, the measurement sent by the UE 802 at 812 may include the third measurement. For example, 1220 may be performed by the TA verification component 198.

[0128] In one aspect, the third measurement may be included in the notification. For example, Fig.10 It is shown at 1012 that the TA invalidation notification may include UL synchronization assistance information. The UL synchronization assistance information may include the third measurement.

[0129] In one aspect, at 1222, the UE may receive a second estimated TA associated with the first cell at a fourth time instance after the third time instance. Fig.10 UE 1002 can receive a new estimated TA, as shown at 1016. 1222 can be performed by TA verification component 198, for example.

[0130] In one aspect, at 1224, the UE may perform a fourth measurement on the at least one DL-RS. For example, Fig.10 At 1018, it is shown that UE 1002 may perform TA verification. The TA verification performed at 1018 may include performing the following steps: Figure 8 1224 can be performed by the TA verification component 198, for example.

[0131] In one aspect, at 1226, the UE may accept or reject the second estimated TA for the communication with the first cell based on at least one of the third measurement or the fourth measurement. Fig.10At 1018, it is shown that UE 1002 may perform TA verification. The TA verification performed at 1018 may include accepting or rejecting the estimated TA, such as Figure 8 As illustrated at 820 of , the estimated TA may be the second estimated TA. For example, 1226 may be performed by the TA verification component 198.

[0132] In one aspect, at 1228, the UE may initiate a RACH procedure with the first cell based on the number of rejected TAs exceeding a threshold number of rejections. For example, Fig.10 At 1020, UE 1002 determines whether a maximum number of TA rejections has been reached, and Fig.10 Initiation of a RACH procedure by the UE 1002 in the event that the maximum number of TA rejections has been reached is shown at 1024. For example, 1228 can be performed by the TA verification component 198.

[0133] In one aspect, if the estimated TA is accepted, the first cell may serve as a SpCell or a SCell. For example, the first cell may be the cell to be activated 906 or the cell to be activated 1006, and the cell to be activated 906 and the cell to be activated 1006 may serve as a SpCell or a SCell. In another example, if the estimated TA is accepted, Figure 7 The deactivated cell 706 in can act as a SpCell.

[0134] Fig.13 1300 is a flow chart of a method of wireless communication. The method may be performed by a network entity (e.g., base station 102, CU 110, DU 130, RU 140, base station 310, base station 804, network entity 1502, etc.). The method may be performed by TA component 199. The method may be associated with various technical advantages at the network entity, such as improving communication reliability via accurate TA.

[0135] At 1302, the network entity receives an indication of a first measurement of at least one DL-RS associated with a first cell at a first time instance, wherein the first cell is included in a set of cells of an L1 mobility configuration or a set of cells of an L2 mobility configuration. Figure 8 At 812, the base station 804 receives the first measurement. In an example, the base station 804 may receive the first measurement. Figure 7 The first measurement is performed on the DL-RS associated with the deactivated cell 706 in the UE. In another example, the first measurement may be a DL timing difference relative to a reference cell at time t1, such as Figure 6 In yet another example, the first cell may be included in Figure 5The cell set 508 of the illustrated L1 / L2 mobility configuration. For example, 1302 can be performed by the TA component 199.

[0136] At 1304, the network entity estimates a TA associated with the first cell based on the first measurement of the at least one DL-RS. Figure 8 The base station 804 estimates the TA for the cell based on the first measurement at 814. For example, 1304 can be performed by the TA component 199.

[0137] At 1306, the network entity sends the estimated TA associated with the first cell at a second time instance after the first time instance. Figure 8 The base station 804 sends the estimated TA at 816. In an example, the first cell may be Figure 7 1306 can be performed by the TA component 199, for example.

[0138] Fig.14 1400 is a flow chart of a method of wireless communication. The method may be performed by a network entity (e.g., base station 102, CU 110, DU 130, RU 140, base station 310, base station 804, network entity 1502, etc.). The method (including various aspects described below) may be performed by TA component 199. The method may be associated with various technical advantages at the network entity, such as improving communication reliability via accurate TA.

[0139] At 1402, the network entity receives an indication of a first measurement of at least one DL-RS associated with a first cell at a first time instance, wherein the first cell is included in a set of cells of an L1 mobility configuration or a set of cells of an L2 mobility configuration. Figure 8 At 812, the base station 804 receives the first measurement. In an example, the base station 804 may receive the first measurement. Figure 7 The first measurement is performed on the DL-RS associated with the deactivated cell 706 in the UE. In another example, the first measurement may be a DL timing difference relative to a reference cell at time t1, such as Figure 6 In yet another example, the first cell may be included in Figure 5 The cell set 508 of the illustrated L1 / L2 mobility configuration. For example, 1402 can be performed by the TA component 199.

[0140] At 1404, the network entity estimates a TA associated with the first cell based on the first measurement of the at least one DL-RS. Figure 8The base station 804 estimates a TA for the cell based on the first measurement at 814. For example, 1404 can be performed by the TA component 199.

[0141] At 1406, the network entity sends the estimated TA associated with the first cell at a second time instance after the first time instance. Figure 8 The base station 804 sends the estimated TA at 816. In an example, the first cell may be Figure 7 1406 can be performed by the TA component 199, for example.

[0142] In one aspect, the first cell may be a deactivated cell in the cell set of the L1 mobility configuration or the cell set of the L2 mobility configuration, and the second cell may serve as a SpCell. Figure 7 , the first cell may be a deactivated cell 706, and the second cell may be a SpCell 704. In another example, the first cell and the second cell may be Figure 5 The cell set 508 of the illustrated L1 / L2 mobility configuration.

[0143] In one aspect, the first measurement may be a DL timing difference measurement between the first cell and a reference cell. Figure 6 DL timing difference measurements relative to a reference cell are shown.

[0144] In one aspect, at 1408, the network entity may receive a notification indicating that the estimated TA has been denied for communication with the first cell. Fig. 9 At 912, SpCell 904 is shown to receive a TA invalidation notification indicating that the estimated TA has been rejected for communication with the cell to be activated 906. For example, Fig.10 At 1012, the SpCell 1004 is shown to receive a TA invalidation notification indicating that the estimated TA has been denied for communication with the cell to be activated 1006. For example, 1408 can be performed by the TA component 199.

[0145] In one aspect, the notification may be received via MAC-CE or UCI. Fig. 9 The TA invalidation notification may be received via MAC-CE or UCI at 912. For example, Fig.10 At 1012, it is shown that the TA invalid notification can be received via MAC-CE or UCI.

[0146] In one aspect, the notification may be associated with an ACK or a NACK. Fig. 9The TA invalidation notification may be associated with an ACK / NACK message as shown at 912. For example, Fig.10 It is shown at 1012 that the TA invalid notification can be associated with an ACK / NACK message.

[0147] In one aspect, at 1410, the network entity may send a PDCCH command based on receiving the notification, the PDCCH command being used to initiate a RACH process with the first cell. Fig. 9 At 914A, it is shown that SpCell 904 sends a PDCCH command, which is used to initiate a RACH process with the cell to be activated 906. For example, 1410 can be performed by the TA component 199.

[0148] In one aspect, at 1412, the network entity may receive an indication of a third measurement at a third time instance after the second time instance, wherein the indication of the third measurement may be received via a MAC-CE or a UCI, and wherein the third measurement may be a DL timing difference measurement between the first cell and a reference cell. For example, Fig.10 The SpCell 1004 is shown receiving a TA invalidation notification including UL synchronization assistance information at 1012. The UL synchronization assistance information may include a third measurement, wherein the third measurement is a DL timing difference. Fig.10 It is also shown at 1012 that the third measurement can be received via MAC-CE or UCI. In yet another example, the SpCell 1004 can receive the third measurement alone. For example, 1412 can be performed by the TA component 199.

[0149] In one aspect, the third measurement may be included in the notification. For example, Fig.10 It is shown at 1012 that the TA invalidation notification may include UL synchronization assistance information, which may include the measurement.

[0150] In one aspect, at 1414, the network entity may estimate a second TA associated with the first cell based on the third measurement. Fig.10 At 1014, the SpCell 1004 is shown estimating a new TA based on the UL synchronization assistance information. For example, 1414 can be performed by the TA component 199.

[0151] In one aspect, at 1416, the network entity may send an estimated second TA associated with the first cell at a fourth time instance after the second time instance. Fig.10At 1016, the SpCell 1004 is shown sending a new estimated TA for the cell to be activated 1006. For example, 1416 can be performed by the TA component 199.

[0152] In one aspect, if the estimated TA is accepted, the first cell may serve as a new SpCell or SCell. For example, the first cell may be the cell to be activated 906 or the cell to be activated 1006, and the cell to be activated 906 and the cell to be activated 1006 may serve as a SpCell or SCell. In another example, if the estimated TA is accepted, Figure 7 The deactivated cell 706 in can act as a SpCell.

[0153] Fig.151500 is a diagram illustrating an example of a hardware implementation for an apparatus 1504. The apparatus 1504 may be a UE, a component of a UE, or may implement UE functionality. In some aspects, the apparatus 1504 may include a cellular baseband processor 1524 (also referred to as a modem) coupled to one or more transceivers 1522 (e.g., a cellular RF transceiver). The cellular baseband processor 1524 may include on-chip memory 1524'. In some aspects, the apparatus 1504 may also include one or more subscriber identity module (SIM) cards 1520 and an application processor 1506 coupled to a secure digital (SD) card 1508 and a screen 1510. The application processor 1506 may include on-chip memory 1506'. In some aspects, the device 1504 may also include a Bluetooth module 1512, a WLAN module 1514, an SPS module 1516 (e.g., a GNSS module), one or more sensor modules 1518 (e.g., an atmospheric pressure sensor / altimeter; a motion sensor such as an inertial measurement unit (IMU), a gyroscope, and / or an accelerometer; light detection and ranging (LIDAR), radio-aided detection and ranging (RADAR), sound navigation and ranging (SONAR), a magnetometer, audio, and / or other technologies for positioning), an additional memory module 1526, a power source 1530, and / or a camera 1532. The Bluetooth module 1512, the WLAN module 1514, and the SPS module 1516 may include an on-chip transceiver (TRX) (or in some cases, only a receiver (RX)). The Bluetooth module 1512, the WLAN module 1514, and the SPS module 1516 may include their own dedicated antennas and / or communicate using an antenna 1580. The cellular baseband processor 1524 communicates with the UE 104 and / or with the RU associated with the network entity 1502 through the transceiver 1522 via one or more antennas 1580. The cellular baseband processor 1524 and the application processor 1506 may each include a computer-readable medium / memory 1524', 1506', respectively. The additional memory module 1526 may also be considered as a computer-readable medium / memory. Each computer-readable medium / memory 1524', 1506', 1526 may be non-transitory. The cellular baseband processor 1524 and the application processor 1506 are each responsible for general processing, including executing software stored on a computer-readable medium / memory. The software enables the cellular baseband processor 1524 / application processor 1506 to perform the various functions described above when executed by the cellular baseband processor 1524 / application processor 1506. The computer-readable medium / memory can also be used to store data manipulated by the cellular baseband processor 1524 / application processor 1506 when executing the software.The cellular baseband processor 1524 / application processor 1506 may be a component of the UE 350 and may include the memory 360 and / or at least one of the TX processor 368, the RX processor 356, and the controller / processor 359. In one configuration, the device 1504 may be a processor chip (modem and / or application) and include only the cellular baseband processor 1524 and / or the application processor 1506, while in another configuration, the device 1504 may be the entire UE (e.g., see. Figure 3 350) and includes additional modules of device 1504.

[0154] As discussed above, the TA verification component 198 is configured to send an indication of a first measurement for at least one DL-RS associated with a first cell at a first time instance, wherein the first cell is included in a set of cells of an L1 mobility configuration or a set of cells of an L2 mobility configuration. The TA verification component 198 is also configured to receive an estimated TA associated with the first cell at a second time instance after the first time instance. The TA verification component 198 is also configured to perform a second measurement on the at least one DL-RS. The TA verification component 198 is also configured to accept or reject the estimated TA for communication with the first cell based on at least one of the first measurement or the second measurement. The TA verification component 198 may be within the cellular baseband processor 1524, the application processor 1506, or both the cellular baseband processor 1524 and the application processor 1506. The TA verification component 198 can be one or more hardware components that are specifically configured to perform the process / algorithm, implemented by one or more processors configured to perform the process / algorithm, stored in a computer-readable medium for implementation by one or more processors, or some combination thereof. As shown, the device 1504 may include multiple components configured for various functions. In one configuration, the device 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes a component for sending an indication of a first measurement for at least one DL-RS associated with a first cell at a first time instance, wherein the first cell is included in a set of cells configured for L1 mobility or a set of cells configured for L2 mobility. In one configuration, the device 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes a component for receiving an estimated TA associated with the first cell at a second time instance after the first time instance. In one configuration, the apparatus 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes means for performing a second measurement on the at least one DL-RS. In one configuration, the apparatus 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes means for accepting or rejecting the estimated TA for communication with the first cell based on at least one of the first measurement or the second measurement. In one configuration, the apparatus 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes means for performing the first measurement on the at least one DL-RS prior to the first time instance, wherein the indication of the first measurement is sent based on the performed first measurement.In one configuration, the apparatus 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes a component for sending a notification indicating that the estimated TA is rejected, wherein the notification is sent when the estimated TA is rejected for the communication with the first cell. In one configuration, the apparatus 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes a component for receiving a PDCCH command after sending the notification. In one configuration, the apparatus 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes a component for initiating a RACH process with the first cell based on the PDCCH command. In one configuration, the apparatus 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes a component for performing a third measurement between the first cell and the reference cell at a third time instance after the second time instance, wherein the third measurement is performed after sending the notification, and wherein the third measurement is a DL timing difference measurement. In one configuration, the device 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes a component for sending an indication of the third measurement via a MAC-CE or UCI. In one configuration, the device 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes a component for receiving a second estimated TA associated with the first cell at a fourth time instance after the third time instance. In one configuration, the device 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes a component for performing a fourth measurement on the at least one DL-RS. In one configuration, the device 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes a component for accepting or rejecting the second estimated TA for the communication with the first cell based on at least one of the third measurement or the fourth measurement. In one configuration, the apparatus 1504 (and in particular the cellular baseband processor 1524 and / or the application processor 1506) includes means for initiating a RACH procedure with the first cell based on the number of rejected TAs exceeding a threshold number of rejections. These means may be the TA verification component 198 of the apparatus 1504 configured to perform the functions recited by these means. As described above, the apparatus 1504 may include the TX processor 368, the RX processor 356, and the controller / processor 359. Thus, in one configuration, these means may be the TX processor 368, the RX processor 356, and / or the controller / processor 359 configured to perform the functions recited by these means.

[0155] Fig.161600 is a diagram illustrating an example of a hardware implementation for a network entity 1602. The network entity 1602 may be a BS, a component of a BS, or may implement BS functionality. The network entity 1602 may include at least one of a CU 1610, a DU 1630, or a RU 1640. For example, depending on the layer functionality handled by the TA component 199, the network entity 1602 may include a CU 1610; both a CU 1610 and a DU 1630; each of the CU 1610, the DU 1630, and the RU 1640; the DU 1630; both a DU 1630 and a RU 1640; or the RU 1640. The CU 1610 may include a CU processor 1612. The CU processor 1612 may include an on-chip memory 1612'. In some aspects, the CU 1610 may also include an additional memory module 1614 and a communication interface 1618. CU 1610 communicates with DU 1630 via a midhaul link, such as an F1 interface. DU 1630 may include a DU processor 1632. DU processor 1632 may include on-chip memory 1632'. In some aspects, DU 1630 may also include an additional memory module 1634 and a communication interface 1638. DU 1630 communicates with RU 1640 via a fronthaul link. RU 1640 may include a RU processor 1642. RU processor 1642 may include on-chip memory 1642'. In some aspects, RU 1640 may also include an additional memory module 1644, one or more transceivers 1646, an antenna 1680, and a communication interface 1648. RU 1640 communicates with UE 104. On-chip memory 1612', 1632', 1642' and additional memory modules 1614, 1634, 1644 can each be considered as a computer-readable medium / memory. Each computer-readable medium / memory can be non-transitory. Each of processors 1612, 1632, 1642 is responsible for general processing, including executing software stored on the computer-readable medium / memory. The software, when executed by the corresponding processor, enables the processor to perform the various functions described above. The computer-readable medium / memory can also be used to store data manipulated by the processor when executing the software.

[0156] As discussed above, the TA component 199 is configured to receive an indication of a first measurement for at least one DL-RS associated with a first cell at a first time instance, wherein the first cell is included in a set of cells of an L1 mobility configuration or a set of cells of an L2 mobility configuration. The TA component 199 is configured to estimate a TA associated with the first cell based on the first measurement for the at least one DL-RS. The TA component 199 is configured to send the estimated TA associated with the first cell at a second time instance after the first time instance. The TA component 199 may be within one or more processors of one or more of the CU 1610, the DU 1630, and the RU 1640. The TA component 199 may be one or more hardware components that are specifically configured to perform the process / algorithm, implemented by one or more processors configured to perform the process / algorithm, stored in a computer-readable medium for implementation by one or more processors, or some combination thereof. The network entity 1602 may include a variety of components configured for various functions. In one configuration, the network entity 1602 includes a component for receiving an indication of a first measurement of at least one DL-RS associated with a first cell at a first time instance, wherein the first cell is included in a set of cells of an L1 mobility configuration or a set of cells of an L2 mobility configuration. In one configuration, the network entity 1602 includes a component for estimating a TA associated with the first cell based on the first measurement of the at least one DL-RS. In one configuration, the network entity 1602 includes a component for sending the estimated TA associated with the first cell at a second time instance after the first time instance. In one configuration, the network entity 1602 includes a component for receiving a notification indicating that the estimated TA has been rejected for communication with the first cell. In one configuration, the network entity 1602 includes a component for sending a PDCCH command based on receiving the notification, the PDCCH command being used to initiate a RACH process with the first cell. In one configuration, the network entity 1602 includes means for receiving an indication of a third measurement at a third time instance after the second time instance, wherein the indication of the third measurement is received via a MAC-CE or a UCI, and wherein the third measurement is a DL timing difference measurement between the first cell and a reference cell. In one configuration, the network entity 1602 includes means for estimating a second TA associated with the first cell based on the third measurement. In one configuration, the network entity 1602 includes means for sending the estimated second TA associated with the first cell at a fourth time instance after the second time instance. These means may be a TA component 199 of the network entity 1602 configured to perform the functions recited by these means.As described above, the network entity 1602 may include the TX processor 316, the RX processor 370, and the controller / processor 375. Thus, in one configuration, these components may be the TX processor 316, the RX processor 370, and / or the controller / processor 375 configured to perform the functions recited by these components.

[0157] The UE may apply the TA to UL transmissions with a cell to take into account the propagation delay between the UE and the cell. When the UE receives signaling from the network for connecting to a cell to be activated in a set of cells configured for L1 / L2 mobility, the network may provide the UE with an estimated TA, wherein the estimated TA may be based on a measurement report sent by the UE to the network. However, the estimated TA may be inaccurate for various reasons. In one example, the channel strength may have changed between the time when the UE last sent a measurement report and the time when the estimated TA was obtained, which may cause the estimated TA to be inaccurate. In another example, the UE may not send measurement reports frequently enough to enable the network to accurately generate the estimated TA. In yet another example, the estimated TA may be inaccurate due to UE mobility, that is, the time when the UE applies the estimated TA may be too far away from the time when the network generates the estimated TA. Applying an inaccurate TA to UL transmissions may affect communication reliability.

[0158] Various techniques for UE-side TA verification are described herein, which may utilize RSRP measurements to represent channel strength. In an example, a UE sends an indication of a first measurement for at least one DL-RS associated with a first cell at a first time instance, wherein the first cell is included in a set of cells configured for L1 mobility or a set of cells configured for L2 mobility. The UE receives an estimated TA associated with the first cell at a second time instance after the first time instance. The UE performs a second measurement on the at least one DL-RS. The UE accepts or rejects the estimated TA for communication with the first cell based on at least one of the first measurement or the second measurement. Via the above-mentioned TA verification process, the UE may be able to reject an inaccurate TA. Therefore, the TA verification process may result in improved communication reliability.

[0159] It should be understood that the specific order or hierarchy of the blocks in the disclosed process / flowchart is merely an illustration of the exemplary method. It should be understood that the specific order or hierarchy of the blocks in the process / flowchart may be rearranged based on design preferences. Further, some blocks may be combined or omitted. The attached method claims provide the elements of the various blocks in a sample order, but are not limited to the specific order or hierarchy provided.

[0160] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects. Therefore, the claims are not limited to the various aspects described herein, but should be given the full scope consistent with the language claims. Unless otherwise specified, reference to an element in the singular form does not mean "one and only one", but "one or more". Terms such as "if", "when" and "while" do not mean a direct temporal relationship or reaction. That is, these phrases, such as "when ...", do not mean an immediate action in response to the occurrence of an action or during the occurrence of an action, but simply imply that if the conditions are met, the action will occur, but no specific or immediate time limit is required for the occurrence of the action. The word "exemplary" is used herein to mean "used as an example, instance, or illustration". Any aspect described as "exemplary" herein is not necessarily interpreted as being preferred or having advantages over other aspects. Unless otherwise specified, the term "some" refers to one or more. Combinations such as "at least one of A, B, or C", "one or more of A, B, or C", "at least one of A, B and C", "one or more of A, B, and C", and "A, B, C, or any combination thereof" include any combination of A, B, and / or C, and may include multiple A, multiple B, or multiple C. Specifically, combinations such as "at least one of A, B, or C", "one or more of A, B, or C", "at least one of A, B, and C", "one or more of A, B, and C", and "A, B, C, or any combination thereof" may be only A, only B, only C, A and B, A and C, B and C, or A and B and C, wherein any such combination may contain one or more members of A, B, or C. A set should be interpreted as a set of elements, wherein the number of elements is one or more. Thus, for a set of X, X will include one or more elements. If the first device receives data from the second device or sends data to the second device, data may be directly received / sent between the first device and the second device, or indirectly received / sent between the first device and the second device through a collection of devices. All structural and functional equivalents of the elements of the various aspects described throughout the present disclosure that are known or will later be known to a person of ordinary skill in the art are expressly incorporated herein by reference and are covered by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly stated in the claims. Words such as "module", "mechanism", "element", "device" cannot replace the word "component". Therefore, no claim element will be understood as a component plus function unless the element is explicitly stated using the phrase "component for..."

[0161] As used herein, the phrase "based on" should not be interpreted as referring to a closed set of information, one or more conditions, one or more factors, etc. In other words, the phrase "based on A" (where "A" can be information, a condition, a factor, etc.) should be interpreted as "based at least on A" unless specifically stated differently.

[0162] The following aspects are merely illustrative and may be combined with other aspects or teachings described herein without limitation.

[0163] Aspect 1 is a method for performing wireless communications at a user equipment (UE), the method comprising: sending an indication of a first measurement of at least one downlink reference signal (DL-RS) associated with a first cell at a first time instance, wherein the first cell is included in a cell set of a layer 1 (L1) mobility configuration or a cell set of a layer 2 (L2) mobility configuration; receiving an estimated timing advance (TA) associated with the first cell at a second time instance after the first time instance; performing a second measurement of the at least one DL-RS; and accepting or rejecting the estimated TA for communication with the first cell based on at least one of the first measurement or the second measurement.

[0164] Aspect 2 is a method according to aspect 1, wherein the estimated TA is accepted or rejected further based on at least one of: a difference between the first measurement and the second measurement; or a reference signal received power (RSRP) threshold of the first cell associated with the second measurement.

[0165] Aspect 3 is a method according to any one of aspects 1 to 2, the method further comprising: performing the first measurement on the at least one DL-RS before the first time instance, wherein the indication of the first measurement is sent based on the performed first measurement.

[0166] Aspect 4 is a method according to any one of Aspects 1 to 3, wherein the first cell is a deactivated cell in the cell set of the L1 mobility configuration or the cell set of the L2 mobility configuration, and wherein the second cell acts as a special cell (SpCell) before accepting or rejecting the estimated TA.

[0167] Aspect 5 is a method according to any one of aspects 1 to 4, wherein the first measurement is a DL timing difference measurement between the first cell and a reference cell, and wherein the second measurement is a reference signal received power (RSRP) measurement.

[0168] Aspect 6 is a method according to any one of aspects 1 to 5, the method further comprising: sending a notification indicating that the estimated TA is rejected, wherein the notification is sent if the estimated TA is rejected for the communication with the first cell.

[0169] Aspect 7 is a method according to aspect 6, wherein the notification is sent via a medium access control (MAC) control element (MAC-CE) or uplink control information (UCI).

[0170] Aspect 8 is a method according to aspect 6, wherein the notification is associated with an acknowledgement (ACK) or a negative acknowledgement (NACK).

[0171] Aspect 9 is a method according to Aspects 6 to 7 or Aspects 6 and 8, the method further comprising: receiving a physical downlink control channel (PDCCH) command after sending the notification; and initiating a random access channel (RACH) process with the first cell based on the PDCCH command.

[0172] Aspect 10 is a method according to aspect 9, wherein the RACH procedure with the first cell is initiated if the first cell will act as a special cell (SpCell).

[0173] Aspect 11 is a method according to Aspect 6, the method further comprising: performing a third measurement between the first cell and the reference cell at a third time instance after the second time instance, wherein the third measurement is performed after sending the notification, and wherein the third measurement is a DL timing difference measurement.

[0174] Aspect 12 is a method according to aspect 11, the method further comprising: sending an indication of the third measurement via a medium access control (MAC) control element (MAC-CE) or uplink control information (UCI).

[0175] Aspect 13 is a method according to aspect 11, wherein the third measurement is included in the notification.

[0176] Aspect 14 is a method according to aspects 11 to 12 or aspects 11 and 13, the method further comprising: receiving a second estimated TA associated with the first cell at a fourth time instance after the third time instance; performing a fourth measurement on the at least one DL-RS; and accepting or rejecting the second estimated TA for the communication with the first cell based on at least one of the third measurement or the fourth measurement.

[0177] Aspect 15 is a method according to aspect 14, the method further comprising: initiating a random access channel (RACH) procedure with the first cell based on the number of rejected TAs exceeding a threshold number of rejections.

[0178] Aspect 16 is a method according to any one of aspects 1 to 15, wherein, if the estimated TA is accepted, the first cell acts as a new special cell (SpCell) or a secondary cell (SCell).

[0179] Aspect 17 is an apparatus for wireless communication at a user equipment (UE), the apparatus comprising a memory and at least one processor, the at least one processor being coupled to the memory and being configured to perform a method according to any one of Aspects 1 to 16 based at least in part on information stored in the memory.

[0180] Aspect 18 is an apparatus for wireless communication, the apparatus comprising means for performing the method according to any one of aspects 1 to 16.

[0181] Aspect 19 is an apparatus according to Aspect 17 or 18, wherein the apparatus further comprises at least one of a transceiver or an antenna coupled to the at least one processor, wherein the transceiver or at least one of the antennas is configured to: send the indication of the first measurement; and receive the estimated TA associated with the first cell.

[0182] Aspect 20 is a non-transitory computer-readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform the method according to any one of aspects 1 to 16.

[0183] Aspect 21 is a method for performing wireless communication at a network entity, the method comprising: receiving an indication of a first measurement of at least one downlink reference signal (DL-RS) associated with a first cell at a first time instance, wherein the first cell is included in a cell set of a layer 1 (L1) mobility configuration or a cell set of a layer 2 (L2) mobility configuration; estimating a timing advance (TA) associated with the first cell based on the first measurement of the at least one DL-RS; and sending the estimated TA associated with the first cell at a second time instance after the first time instance.

[0184] Aspect 22 is a method according to aspect 21, wherein the first cell is a deactivated cell in the cell set of the L1 mobility configuration or the cell set of the L2 mobility configuration, and wherein the second cell acts as a special cell (SpCell).

[0185] Aspect 23 is a method according to any one of aspects 21 to 22, wherein the first measurement is a DL timing difference measurement between the first cell and a reference cell.

[0186] Aspect 24 is a method according to any one of aspects 21 to 23, the method further comprising: receiving a notification indicating that the estimated TA has been rejected for communication with the first cell.

[0187] Aspect 25 is a method according to aspect 24, wherein the notification is received via a medium access control (MAC) control element (MAC-CE) or uplink control information (UCI).

[0188] Aspect 26 is a method according to aspect 24, wherein the notification is associated with an acknowledgement (ACK) or a negative acknowledgement (NACK).

[0189] Aspect 27 is a method according to Aspects 24 to 25 or Aspects 24 and 26, the method further comprising: sending a physical downlink control channel (PDCCH) command based on receiving the notification, the physical downlink control channel (PDCCH) command being used to initiate a random access channel (RACH) process with the first cell.

[0190] Aspect 28 is a method according to Aspect 24, the method further comprising: receiving an indication of a third measurement at a third time instance after the second time instance, wherein the indication of the third measurement is received via a medium access control (MAC) control element (MAC-CE) or uplink control information (UCI), and wherein the third measurement is a DL timing difference measurement between the first cell and a reference cell.

[0191] Aspect 29 is a method according to aspect 28, wherein the third measurement is included in the notification.

[0192] Aspect 30 is a method according to any one of Aspects 28 to 29, the method further comprising: estimating a second TA associated with the first cell based on the third measurement; and sending the estimated second TA associated with the first cell at a fourth time instance after the second time instance.

[0193] Aspect 31 is a method according to any one of aspects 21 to 30, wherein, if the estimated TA is accepted, the first cell acts as a new special cell (SpCell) or a secondary cell (SCell).

[0194] Aspect 32 is an apparatus for wireless communication at a user equipment (UE), the apparatus comprising a memory and at least one processor, the at least one processor being coupled to the memory and being configured to perform a method according to any one of Aspects 21 to 31 based at least in part on information stored in the memory.

[0195] Aspect 33 is an apparatus for wireless communication, the apparatus comprising means for performing a method according to any one of aspects 21 to 31.

[0196] Aspect 34 is an apparatus according to Aspect 32 or 33, wherein the apparatus further comprises at least one of a transceiver or an antenna coupled to the at least one processor, wherein the transceiver or at least one of the antenna is configured to: receive the indication of the first measurement; and send the estimated TA.

[0197] Aspect 35 is a non-transitory computer-readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform the method according to any one of aspects 21 to 31.

Claims

1. An apparatus for wireless communication at a user equipment (UE), the apparatus comprising: Memory; and at least one processor coupled to the memory and based at least in part on the information stored in the memory, the at least one processor configured to: sending, at a first time instance, an indication of a first measurement of at least one downlink reference signal (DL-RS) associated with a first cell, wherein the first cell is included in a set of cells of a layer 1 (L1) mobility configuration or a set of cells of a layer 2 (L2) mobility configuration; receiving an estimated timing advance (TA) associated with the first cell at a second time instance after the first time instance; performing a second measurement on the at least one DL-RS; as well as The estimated TA is accepted or rejected for communication with the first cell based on at least one of the first measurement or the second measurement.

2. The apparatus of claim 1 , wherein the estimated TA is accepted or rejected based further on at least one of: a difference between the first measurement and the second measurement; or a reference signal received power (RSRP) threshold of the first cell associated with the second measurement.

3. The apparatus of claim 1 , wherein the at least one processor is further configured to: The first measurement is performed on the at least one DL-RS prior to the first time instance, wherein the indication of the first measurement is sent based on the performed first measurement.

4. The apparatus according to claim 1, wherein the first cell is a deactivated cell in the cell set of the L1 mobility configuration or the cell set of the L2 mobility configuration, wherein before accepting or rejecting the estimated TA, the second cell acts as a special cell (SpCell).

5. The apparatus of claim 1, wherein the first measurement is a DL timing difference measurement between the first cell and a reference cell, and wherein the second measurement is a reference signal received power (RSRP) measurement.

6. The apparatus of claim 1, wherein the at least one processor is further configured to: A notification is sent indicating that the estimated TA is rejected, wherein the notification is sent if the estimated TA is rejected for the communication with the first cell.

7. The apparatus of claim 6, wherein the notification is sent via a medium access control (MAC) control element (MAC-CE) or uplink control information (UCI).

8. The apparatus of claim 6, wherein the notification is associated with an acknowledgement (ACK) or a negative acknowledgement (NACK).

9. The apparatus of claim 6, wherein the at least one processor is further configured to: receiving a physical downlink control channel (PDCCH) order after sending the notification; and A random access channel (RACH) procedure with the first cell is initiated based on the PDCCH order.

10. The apparatus of claim 9, wherein the RACH procedure with the first cell is initiated if the first cell is to act as a special cell (SpCell).

11. The apparatus of claim 6, wherein the at least one processor is further configured to: A third measurement between the first cell and a reference cell is performed at a third time instance after the second time instance, wherein the third measurement is performed after sending the notification, and wherein the third measurement is a DL timing difference measurement.

12. The apparatus of claim 11, wherein the at least one processor is further configured to: The indication of the third measurement is sent via a medium access control (MAC) control element (MAC-CE) or uplink control information (UCI).

13. The apparatus of claim 11, wherein the third measurement is included in the notification.

14. The apparatus of claim 11, wherein the at least one processor is further configured to: receiving a second estimated TA associated with the first cell at a fourth time instance after the third time instance; performing a fourth measurement on the at least one DL-RS; and The second estimated TA is accepted or rejected for the communication with the first cell based on at least one of the third measurement or the fourth measurement.

15. The apparatus of claim 14, wherein the at least one processor is further configured to: A random access channel (RACH) procedure with the first cell is initiated based on the number of rejected TAs exceeding a threshold number of rejections. 16 . The apparatus of claim 1 , wherein in a case where the estimated TA is accepted, the first cell acts as a new special cell (SpCell) or a secondary cell (SCell).

17. The apparatus of claim 1, further comprising at least one of a transceiver or an antenna coupled to the at least one processor, wherein the transceiver or at least one of the antenna is configured to: send the indication of the first measurement; and receive the estimated TA.

18. A method of wireless communication at a user equipment (UE), the method comprising: sending, at a first time instance, an indication of a first measurement of at least one downlink reference signal (DL-RS) associated with a first cell, wherein the first cell is included in a set of cells of a layer 1 (L1) mobility configuration or a set of cells of a layer 2 (L2) mobility configuration; receiving an estimated timing advance (TA) associated with the first cell at a second time instance after the first time instance; performing a second measurement on the at least one DL-RS; as well as The estimated TA is accepted or rejected for communication with the first cell based on at least one of the first measurement or the second measurement.

19. An apparatus for wireless communication at a network entity, the apparatus comprising: Memory; and at least one processor coupled to the memory and based at least in part on the information stored in the memory, the at least one processor configured to: receiving, at a first time instance, an indication of a first measurement of at least one downlink reference signal (DL-RS) associated with a first cell, wherein the first cell is included in a set of cells of a layer 1 (L1) mobility configuration or a set of cells of a layer 2 (L2) mobility configuration; estimating a timing advance (TA) associated with the first cell based on the first measurement of the at least one DL-RS; as well as An estimated TA associated with the first cell is sent at a second time instance after the first time instance. 20 . The apparatus of claim 19 , wherein the first cell is a deactivated cell in the cell set of the L1 mobility configuration or the cell set of the L2 mobility configuration, and wherein the second cell serves as a special cell (SpCell).

21. The apparatus of claim 19, wherein the first measurement is a DL timing difference measurement between the first cell and a reference cell.

22. The apparatus of claim 19, wherein the at least one processor is further configured to: A notification is received indicating that the estimated TA has been denied for communication with the first cell.

23. The apparatus of claim 22, wherein the notification is received via a medium access control (MAC) control element (MAC-CE) or uplink control information (UCI).

24. The apparatus of claim 22, wherein the notification is associated with an acknowledgement (ACK) or a negative acknowledgement (NACK).

25. The apparatus of claim 22, wherein the at least one processor is further configured to: A physical downlink control channel (PDCCH) order is sent based on receiving the notification, the physical downlink control channel (PDCCH) order being used to initiate a random access channel (RACH) procedure with the first cell.

26. The apparatus of claim 22, wherein the at least one processor is further configured to: An indication of a third measurement is received at a third time instance after the second time instance, wherein the indication of the third measurement is received via a medium access control (MAC) control element (MAC-CE) or uplink control information (UCI), and wherein the third measurement is a DL timing difference measurement between the first cell and a reference cell.

27. The apparatus of claim 26, wherein the third measurement is included in the notification.

28. The apparatus of claim 26, wherein the at least one processor is further configured to: estimating a second TA associated with the first cell based on the third measurement; and An estimated second TA associated with the first cell is sent at a fourth time instance after the second time instance.

29. The apparatus of claim 19, further comprising at least one of a transceiver or an antenna coupled to the at least one processor, wherein the transceiver or at least one of the antenna is configured to: receive the indication of the first measurement; and send the estimated TA.

30. A method for wireless communication at a network entity, the method comprising: receiving, at a first time instance, an indication of a first measurement of at least one downlink reference signal (DL-RS) associated with a first cell, wherein the first cell is included in a set of cells of a layer 1 (L1) mobility configuration or a set of cells of a layer 2 (L2) mobility configuration; estimating a timing advance (TA) associated with the first cell based on the first measurement of the at least one DL-RS; as well as An estimated TA associated with the first cell is sent at a second time instance after the first time instance.

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