Determination of l2 reset in lower layer mobility

Abstract

A method for wireless communication at a user equipment (UE) is provided. In the method, the UE receives, via Radio Resource Control (RRC), a configuration of a plurality of candidate cells for Layer 1 (L1) or Layer 2 (L2) inter-cell mobility from a network entity, and receives, from the network entity, information on L2 reset when switching between the plurality of candidate cells. The UE then performs a serving cell handover within the candidate cell for the UE in response to the L1 or L2 signaling, and resets or reuses an L2 cell configuration based on the information in response to the serving cell handover.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit and priority of U.S. Provisional Application Serial No. 63 / 382,285, entitled "DETERMINATION OF L2 RESET IN LOWER LAYER MOBILITY", filed on November 3, 2022, and U.S. Non - Provisional Patent Application Serial No. 18 / 479,743, entitled "DETERMINATION OF L2 RESET IN LOWER LAYER MOBILITY", filed on October 2, 2023, the entire disclosures of which are hereby incorporated by reference in their entireties. Technical Field

[0003] The present disclosure generally relates to communication systems, and more particularly, to determining a layer 2 (L2) reset in lower layer mobility for wireless communication. Background Art

[0004] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasting. A typical wireless communication system 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 the urban, national, regional, and even global levels. One example of a 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. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine - type communication (mMTC), and ultra - reliable low - latency communication (URLLC). Some aspects of 5G NR may be based on the 4G Long - Term Evolution (LTE) standard. Further improvements to 5G NR technology are needed. 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] The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects. The summary neither identifies key or critical 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 the more detailed description that is presented later.

[0007] In one aspect of the present disclosure, there are provided methods, computer-readable media, and apparatuses for wireless communication at a user equipment (UE). The apparatus may include at least one memory and at least one processor coupled to the at least one memory. At least partially based on information stored in the at least one memory, the at least one processor may be configured, individually or in any combination, to: receive, via radio resource control (RRC), a configuration of a plurality of candidate cells for layer 1 (L1) or L2 inter-cell mobility from a network entity; receive, from the network entity, information regarding L2 reset when switching between the plurality of candidate cells; perform a serving cell handover within the candidate cells for the UE in response to L1 or L2 signaling; and reset or reuse an L2 cell configuration in response to the serving cell handover and based on the information.

[0008] In one aspect of the present disclosure, there are provided methods, computer-readable media, and apparatuses for wireless communication at a network entity. The apparatus may include at least one memory and at least one processor coupled to the at least one memory. At least partially based on information stored in the at least one memory, the at least one processor may be configured, individually or in any combination, to: send, via RRC, a configuration of a plurality of candidate cells for L1 or L2 inter-cell mobility to a UE; and send, to the UE, information regarding L2 reset when switching between the plurality of candidate cells, so that the UE performs a cell handover between the plurality of candidate cells. The UE may perform the cell handover by: performing a serving cell handover within the candidate cells for the UE in response to L1 or L2 signaling, and resetting or reusing an L2 cell configuration in response to the serving cell handover and based on the information.

[0009] To achieve the foregoing and related purposes, one or more aspects may include the features described in detail hereinafter and particularly pointed out in the claims. The following description and the drawings set forth in detail some illustrative features of one or more aspects. However, these features indicate only some of the various ways in which the principles of the various aspects may 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 FIG. is an illustration showing an example of a first frame according to various aspects of the present disclosure.

[0012] Figure 2B FIG. is an illustration showing an example of a downlink (DL) channel within a subframe according to various aspects of the present disclosure.

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

[0014] Figure 2D FIG. is an illustration showing an example of an uplink (UL) channel within a subframe according to various aspects of the present disclosure.

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

[0016] Figure 4 FIG. is an illustration showing an example of a cell configuration.

[0017] Figure 5 FIG. is an illustration showing the overall architecture of a next-generation radio access network (NG-RAN).

[0018] Figure 6 FIG. is an illustration showing an example of lower layer mobility.

[0019] Figure 7A and Figure 7B FIG. is an illustration showing an L2 reset during lower layer mobility.

[0020] Figure 8A and Figure 8B FIG. is an illustration showing continuous lower layer cell handover.

[0021] Figure 9 FIG. is a call flow diagram showing a method of wireless communication according to various aspects of the present disclosure.

[0022] Figure 10 FIG. is a first flowchart showing a method of wireless communication at a UE according to various aspects of the present disclosure.

[0023] Figure 11 FIG. is a first flowchart showing a method of wireless communication at a UE according to various aspects of the present disclosure.

[0024] Figure 12 FIG. is a first flowchart showing a method of wireless communication at a network entity according to various aspects of the present disclosure.

[0025] Figure 13 FIG. is a first flowchart showing a method of wireless communication at a network entity according to various aspects of the present disclosure.

[0026] Figure 14 It is a diagram illustrating an example of the hardware implementation of an exemplary apparatus and / or network entity.

[0027] Figure 15 It is a diagram illustrating an example of the hardware implementation of an exemplary network entity. Detailed Description

[0028] Compared with service cell change using layer 3 (L3) handover, a UE can change its service cell through lower layer (L1 / L2) mobility to reduce communication overhead. Various example aspects presented herein include methods and apparatuses for determining an L2 reset in lower layer mobility for wireless communication. In one aspect, a UE can receive, via RRC from a network entity, a configuration of multiple candidate cells for L1 or L2 inter-cell mobility (e.g., L1 / L2 triggered mobility or LTM), and receive information from the network entity regarding an L2 reset when switching between the multiple candidate cells. The UE can further perform a service cell handover within a candidate cell for the UE in response to L1 or L2 signaling, and reset or reuse the L2 cell configuration in response to the service cell handover and based on the information. The method enables a single or consecutive service cell handover through lower layer (e.g., L2) inter-cell mobility. Thus, it reduces the communication overhead when switching service cells. Additionally, the security of wireless communication is improved by sending information related to service cell handover via multiple indications.

[0029] Certain aspects of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. In some examples, the described techniques can be used to reduce the communication overhead when switching service cells by enabling a single or consecutive service cell handover through lower layer (e.g., L2) inter-cell mobility. In some aspects, the described techniques improve the security of wireless communication by sending information related to service cell handover via multiple indications.

[0030] The detailed description set forth below in connection with the appended drawings is a description of various configurations and does not represent the only configurations in which the concepts described herein can be practiced. To provide a thorough understanding of the various concepts, the detailed description includes specific details. However, the concepts can be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0031] Various aspects of a telecommunications system are presented with reference to various apparatuses and methods. These apparatuses 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 can be implemented using electronic hardware, computer software, or any combination thereof. Whether these elements are implemented as hardware or software depends on the particular 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" that includes one or more processors. When multiple processors are implemented, the multiple processors can perform functions individually or in combination. 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 a chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gate logic, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout this disclosure. One or more processors in the processing system can execute software. Software should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executables, execution threads, processes, functions, or any combination thereof, regardless of whether it is referred to as software, firmware, middleware, microcode, hardware description language, or other terms.

[0033] Thus, in one or more example aspects, embodiments, and / or use cases, the described functionality can be implemented in hardware, software, or any combination thereof. If implemented in software, the functionality can be stored or encoded on a computer-readable medium as one or more instructions or code. Computer-readable media includes computer storage media. Storage media can be any available medium that can be accessed by a computer. By way of example, such computer-readable media can 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 medium 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] While aspects, embodiments, and / or use cases are described by way of some examples in this application, additional or different aspects, embodiments, and / or use cases may arise in many different arrangements and scenarios. The aspects, embodiments, and / or use cases described herein may be implemented across many different platform types, devices, systems, shapes, sizes, and packaging arrangements. For example, the aspects, embodiments, and / or use cases may be embodied via integrated chips and other non-module-component-based devices (e.g., end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail / purchase devices, medical devices, artificial intelligence (AI)-enabled devices, etc.). Although some examples may or may not be specifically targeted at use cases or applications, the described examples may have broad applicability. The aspects, embodiments, and / or use cases may range from chip-level or modular components to non-modular, non-chip-level embodiments, and further to aggregated, distributed, or original equipment manufacturer (OEM) devices or systems incorporating one or more of the technologies herein. In some practical settings, devices incorporating the described aspects and features 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 includes 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 techniques described herein may be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, aggregated components, or disaggregated components, end-user devices, etc., of various sizes, shapes, and configurations.

[0035] The deployment of a communication system (such as a 5G NR system) can be arranged with various components or constituent parts in multiple ways. In a 5G NR system or network, network nodes, network entities, mobility elements of the network, radio access network (RAN) nodes, core network nodes, network elements, or network equipment (such as a base station (BS)), or one or more units (or one or more components) performing base station functionality can be implemented in an aggregated or disaggregated architecture. For example, a BS (such as a Node B (NB), evolved NB (eNB), NR BS, 5G NB, access point (AP), transmit receive point (TRP), or cell, etc.) can be implemented as an aggregated base station (also referred to as a stand-alone BS or monolithic BS) or a disaggregated base station.

[0036] A centralized base station may be configured to utilize a radio protocol stack that is physically or logically integrated within a single RAN node. A split base station may be configured to utilize a protocol stack that is 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 among one or more other RAN nodes. A DU may be implemented to communicate with one or more RUs. Each of the CU, DU, and 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 consider the aggregation characteristics of base station functionality. For example, a split base station may be utilized in an integrated access backhaul (IAB) network, an open radio access network (O-RAN, such as a network configuration initiated by the O-RAN Alliance), or a virtualized radio access network (vRAN, also known as a cloud radio access network (C-RAN)). Splitting may include distributing functions across two or more units at various physical locations, as well as virtualizing the function of at least one unit, which may achieve flexibility in network design. The various units of a split base station or a split RAN architecture may be configured for wired or wireless communication with at least one other unit.

[0038] Figure 1 FIG. 100 is a diagram illustrating an example of a wireless communication system and an access network. The illustrated wireless communication system includes a split base station architecture. The split base station architecture may include one or more CUs 110, which may communicate directly with the core network 120 via a backhaul link, or indirectly with the core network 120 through one or more split 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 a respective midhaul link, such as an F1 interface. The DU 130 may communicate with one or more RUs 140 via a respective fronthaul link. The RU 140 may communicate with a respective UE 104 via one or more radio frequency (RF) access links. In some embodiments, the UE 104 may be served simultaneously by multiple RUs 140.

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

[0040] In some aspects, the 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 utilize an interface that is configured to communicate signals with other control functions hosted by the CU 110. The 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 embodiments, the 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 units may communicate bidirectionally with the CU-CP units via an interface (such as an E1 interface). As needed, the CU 110 may be implemented to communicate with the DU 130 for network control and signaling.

[0041] The 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, the DU 130 may host one or more of the Radio Link Control (RLC) layer, 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 partially based on a functional split (such as those defined by 3GPP). In some aspects, the DU 130 may also host one or more low PHY layers. Each layer (or module) may utilize an interface that is configured to communicate signals with other layers (and modules) hosted by the DU 130 or with control functions hosted by the CU 110.

[0042] The lower layer functionality can be implemented by one or more RUs 140. In some deployments, the RUs 140 controlled by the DU 130 can correspond to logical nodes that host 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, at least in part based on a functional split (such as a lower layer functional split). In such an architecture, the RU 140 can be implemented to handle over-the-air (OTA) communication with one or more UEs 104. In some embodiments, the real-time and non-real-time aspects of the control plane and user plane communication with the RU 140 can be controlled by the corresponding DU 130. In some scenarios, this configuration enables the implementation of the DU 130 and CU 110 in a cloud-based RAN architecture (such as a vRAN architecture).

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

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

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

[0046] At least one of CU 110, DU 130, and RU 140 may be referred to as base station 102. Thus, base station 102 may include one or more of CU 110, DU 130, and RU 140 (each component is indicated by a dashed line to indicate that each component may or may not be included in base station 102). Base station 102 provides an access point to core network 120 for UE 104. Base station 102 may include macro cells (high-power cellular base stations) and / or small cells (low-power cellular base stations). 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. The heterogeneous network may also include a home evolved Node B (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 an uplink (UL) (also referred to as a reverse link) transmission from UE 104 to RU 140 and / or a downlink (DL) (also referred to as a forward link) transmission from RU 140 to UE 104. The communication link may use multiple-input multiple-output (MIMO) antenna techniques, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link may be via one or more carriers. For each carrier allocated in carrier aggregation with a total of up to Yx MHz (x component carriers) for transmission in each direction, base station 102 / UE 104 may use a spectrum with a bandwidth of up to Y MHz (e.g., 5 MHz, 10 MHz, 15 MHz, 20 MHz, 100 MHz, 400 MHz, etc.). The 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 for DL compared 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 carriers may be referred to as secondary cells (SCells).

[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). D2D communication may be carried out via various wireless D2D communication systems, such as for example Bluetooth TM (Bluetooth is a trademark of the Bluetooth Special Interest Group (SIG)), Wi-Fi based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards TM(Wi-Fi is a trademark of the Wi-Fi Alliance), LTE, or NR.

[0048] The wireless communication system may also include a Wi-Fi AP 150 that communicates with the UE 104 (also referred to as a Wi-Fi station (STA)) via a communication link 154, e.g., in the 5 GHz unlicensed spectrum or the like. When communicating in the unlicensed spectrum, the UE 104 / AP 150 may perform a Clear Channel Assessment (CCA) before communication to determine whether the channel is available.

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

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

[0051] Considering the above aspects, unless otherwise specifically stated, if the term "sub-6 GHz" or the like is used herein, it may broadly represent frequencies that may be less than 6 GHz, may be within FR1, or may include mid-band frequencies. In addition, unless otherwise specifically stated, if the term "millimeter wave" or the like is used herein, it may broadly represent 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] Base station 102 and UE 104 may each include multiple antennas (such as antenna elements, antenna panels, and / or antenna arrays) to facilitate beamforming. Base station 102 may transmit beamformed signal 182 to UE 104 in one or more transmission directions. UE 104 may receive the beamformed signal from base station 102 in one or more reception directions. UE 104 may also transmit beamformed signal 184 to base station 102 in one or more transmission directions. Base station 102 may receive the beamformed signal from UE 104 in one or more reception directions. Base station 102 / UE 104 may perform beam training to determine the optimal reception direction and transmission direction for each of base station 102 / UE 104. The transmission direction and reception direction of base station 102 may be the same or may not be the same. The transmission direction and reception direction of UE 104 may be the same or may not be the same.

[0053] Base station 102 may include and / or be referred to as gNB, Node B, eNB, access point, transceiver base station, radio base station, radio transceiver, transceiver function, basic service set (BSS), extended service set (ESS), TRP, network node, network entity, network equipment, or some other suitable term. Base station 102 may be implemented as an integrated access and backhaul (IAB) node, relay node, sidelink node, a converged (monolithic) base station with a baseband unit (BBU) (including CU and DU) and RU, or be implemented as a decomposed base station including one or more of CU, DU, and / or RU. A set of base stations including decomposed base stations and / or converged base stations may be referred to as 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. The AMF 161 is a control node that processes signaling between the UE 104 and the core network 120. The AMF 161 supports registration management, connection management, mobility management, and other functions. The SMF 162 supports session management and other functions. The UPF 163 supports packet routing, packet forwarding, and other functions. The 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, one or more Location Servers 168 may include one or more location / locationing servers, which may include one or more of the GMLC 165, the LMF 166, a Position Determination Entity (PDE), a Serving Mobile Location Center (SMLC), a Mobile Positioning Center (MPC), etc. The GMLC 165 and the LMF 166 support UE location services. The GMLC 165 provides an interface for clients / applications (e.g., emergency services) to access UE location information. The LMF 166 receives measurements and assistance information from the NG-RAN and the UE 104 via the AMF 161 to calculate the location of the UE 104. The NG-RAN may utilize one or more positioning methods to determine the location of the UE 104. Positioning the UE 104 may involve signal measurements, position estimation, and an optional speed calculation based on these measurements. The signal measurements may be performed by the UE 104 and / or the base station 102 serving the UE 104. The measured signals may be based on a Satellite Positioning System (SPS) 170 (e.g., a Global Navigation Satellite System (GNSS), a Global Positioning System (GPS), a Non-Terrestrial Network (NTN), or one or more of other satellite positioning / location systems), an LTE signal, a Wireless Local Area Network (WLAN) signal, a Bluetooth signal, 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, an NR signal (e.g., multi-round-trip time (multi-RTT), DL Departure Angle (DL-AoD), DL Time Difference of Arrival (DL-TDOA), UL Time Difference of Arrival (UL-TDOA), and UL Arrival Angle (UL-AoA) positioning), and / or one or more of other systems / signals / sensors.

[0055] Examples of the UE 104 include cellular phones, smart phones, Session Initiation Protocol (SIP) phones, laptop computers, personal digital assistants (PDAs), satellite radios, global positioning systems, multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, tablet devices, smart devices, wearable devices, vehicles, electricity meters, air pumps, large or small kitchen appliances, healthcare devices, implants, sensors / actuators, displays, or any other device with similar functionality. Some of the UEs in the UE 104 may be referred to as IoT devices (e.g., parking meters, air pumps, toasters, vehicles, heart monitors, etc.). The UE 104 may also be referred to as a station, mobile station, subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, cell phone, user agent, mobile client, client, or some other suitable term. In some scenarios, the term UE may also apply to one or more companion devices, such as in a device constellation arrangement. One or more of these devices may access the network jointly and / or access the network individually.

[0056] Referring again to Figure 1 , in some aspects, the UE 104 may include an L2 reset receiving component 198. The L2 reset receiving component 198 may be configured to: receive, via RRC, a configuration of a plurality of candidate cells for L1 or L2 inter-cell mobility (e.g., L1 / L2 triggered mobility or LTM) from a network entity; receive information about L2 reset when switching between the plurality of candidate cells from the network entity; perform a serving cell handover within the candidate cell for the UE in response to L1 or L2 signaling; and reset or reuse the L2 cell configuration in response to the serving cell handover and based on the information. In some aspects, the base station 102 may include an L2 reset indication component 199. The L2 reset indication component 199 may be configured to: send, via RRC, a configuration of a plurality of candidate cells for L1 or L2 inter-cell mobility to the UE; and send information about L2 reset when switching between the plurality of candidate cells to the UE, so that the UE performs a cell handover between the plurality of candidate cells. The UE may perform the cell handover by: performing a serving cell handover within the candidate cell for the UE in response to L1 or L2 signaling, and resetting or reusing the L2 cell configuration in response to the serving cell handover and based on the information. 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 2AFIG. 200 is an illustration example of a first subframe within a 5G NR frame structure. Figure 2B FIG. 230 is an illustration example of a DL channel within a 5G NR subframe. Figure 2C FIG. 250 is an illustration example of a second subframe within a 5G NR frame structure. Figure 2D FIG. 280 is an illustration example of a UL channel within a 5G NR subframe. The 5G NR frame structure can be Frequency Division Duplexing (FDD) (wherein for a specific set of subcarriers (carrier system bandwidth), the subframes within that set of subcarriers are dedicated to either DL or UL), or can be Time Division Duplexing (TDD) (wherein for a specific set of subcarriers (carrier system bandwidth), the subframes within that set of subcarriers are dedicated to both DL and UL). In Figure 2A 、 Figure 2C the example provided, the 5G NR frame structure is assumed to be TDD, where subframe 4 is configured with slot format 28 (where most are DL), where D is DL, U is UL, and F is flexibly usable between DL / UL, and subframe 3 is configured with slot format 1 (where all are UL). Although subframes 3 and 4 are shown as having slot formats 1 and 28 respectively, any particular subframe can be configured with any one of the various available slot formats 0 - 61. Slot formats 0 and 1 are all DL and UL respectively. The other slot formats 2 - 61 include a mixture of DL, UL, and flexible symbols. The slot format is configured for the UE by the received Slot Format Indicator (SFI) (configured dynamically by Downlink Control Information (DCI) or semi-statically / statically by Radio Resource Control (RRC) signaling). Note that the following description also applies to the 5G NR frame structure as TDD.

[0058] Figures 2A to 2DA frame structure is illustrated, and 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 (10 ms) may be divided into 10 equal-sized subframes (1 ms). Each subframe may include one or more time slots. A subframe may also include mini-slots, 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 normal CP, each time slot may include 14 symbols, and for extended CP, each time slot may include 12 symbols. The symbols on the DL may be cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) symbols. The symbols on the UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (for power-constrained scenarios; limited to single-stream transmission). The number of time slots within a subframe is based on the CP and the parameter set. The parameter set defines the subcarrier spacing (SCS) (see Table 1). The symbol length / duration may be scaled with 1 / SCS.

[0059]

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

[0061] For normal CP (14 symbols / slot), the different parameter sets μ0 to 4 allow 1, 2, 4, 8, and 16 time slots per subframe, respectively. For extended CP, parameter set 2 allows 4 time slots per subframe. Thus, for normal CP and parameter set μ, there are 14 symbols / slot and 2 μ time slots / subframe. The subcarrier spacing may be equal to 2 μ * 15 kHz, where μ is parameter set 0 to 4. Thus, the subcarrier spacing for parameter set μ = 0 is 15 kHz, and the subcarrier spacing for parameter set μ = 4 is 240 kHz. The symbol length / duration is inversely related to the subcarrier spacing. Figures 2A to 2D An example is provided with normal CP having 14 symbols per time slot and parameter set μ = 2 having 4 time slots per subframe. The time slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 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 time slot includes a resource block (RB) (also referred to as a physical RB (PRB)) that extends 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

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

[0064] Figure 2B Examples of various DL channels within a subframe of a frame are illustrated. The 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 resource element groups (REGs), each REG including 12 consecutive RES in the OFDM symbols of an RB. The PDCCH within a BWP may be referred to as a control resource set (CORESET). The UE is configured to monitor PDCCH candidates in the PDCCH search space (e.g., common search space, UE-specific search space) during PDCCH monitoring occasions on the CORESET, where 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. The primary synchronization signal (PSS) may be in symbol 2 of a particular subframe of the frame. The PSS is used by the UE 104 to determine subframe / symbol timing and the physical layer identity. The secondary synchronization signal (SSS) may be in symbol 4 of a particular subframe of the frame. The SSS is used by the UE to determine the physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE may determine the physical cell identifier (PCI). Based on the PCI, the UE may determine the location of the DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) may 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 transmitted via the PBCH (such as system information blocks (SIBs)), and paging messages.

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

[0066] Figure 2D Examples of various UL channels within a subframe of a frame are illustrated. The PUCCH can be located at the position indicated in one configuration. The PUCCH carries uplink control information (UCI), such as a scheduling request, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), and a 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 can additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and / or UCI.

[0067] Figure 3It is a block diagram of the communication between the base station 310 and the UE 350 in the access network. In the DL, Internet Protocol (IP) packets can be provided to the controller / processor 375. The controller / processor 375 implements layer 3 and layer 2 functionality. Layer 3 includes the Radio Resource Control (RRC) layer, and layer 2 includes the Service Data Adaptation Protocol (SDAP) layer, the Packet Data Convergence Protocol (PDCP) layer, the Radio Link Control (RLC) layer, and the Medium Access Control (MAC) layer. The controller / processor 375 provides RRC layer functionality associated with the broadcast 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 the transfer of upper layer packet data units (PDUs), error correction via ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and re-ordering of RLC data PDUs; and MAC layer functionality associated with the 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 via HARQ, priority handling, and logical channel prioritization.

[0068] The transmit (TX) processor 316 and the 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) encoding / 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 processes the mapping to the signal constellation based on various modulation schemes such as binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase phase shift keying (M-PSK), and M-phase quadrature amplitude modulation (M-QAM). The encoded and modulated symbols can then be split into parallel streams. Subsequently, each stream can be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time domain and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to generate a physical channel carrying a stream of time-domain OFDM symbols. The OFDM stream is precoded in space to generate multiple spatial streams. Channel estimates from the channel estimator 374 can be used to determine the encoding and modulation schemes, as well as for spatial processing. The channel estimates can be derived from reference signals transmitted by the UE 350 and / or channel state feedback. Each spatial stream can then be provided to a different antenna 320 via a separate transmitter 318Tx. Each transmitter 318Tx can modulate a radio frequency (RF) carrier using the corresponding spatial stream for transmission.

[0069] At the UE 350, each receiver 354Rx receives signals via its corresponding antenna 352. Each receiver 354Rx recovers the information modulated onto the RF carrier and provides the information to the 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 streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they can be combined by the RX processor 356 into a single OFDM symbol stream. The RX processor 356 then uses a fast Fourier transform (FFT) to convert the OFDM symbol stream from the time domain to the frequency domain. 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 points transmitted by the base station 310. These soft decisions can be based on the channel estimates computed by the channel estimator 358. Subsequently, the soft decisions are decoded and deinterleaved to recover the data and control signals originally transmitted by the base station 310 on the physical channel. The data and control signals are then provided to the controller / processor 359, which implements layer 3 and layer 2 functionality.

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

[0071] Similar to the functions described in connection with DL transmission 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 the transfer of upper layer PDUs, error correction via ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with the mapping between the logical channel and the transport channel, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via HARQ, priority handling, and logical channel prioritization.

[0072] The TX processor 368 may use channel estimates derived from reference signals or feedback sent by the base station 310 by the channel estimator 358 to select appropriate decoding 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 a separate transmitter 354Tx. Each transmitter 354Tx may modulate an RF carrier with a corresponding spatial stream for transmission.

[0073] UL transmission is processed at the base station 310 in a manner similar to that described in connection with the receiver function at the UE 350. Each receiver 318Rx receives signals via its corresponding antenna 320. Each receiver 318Rx recovers the information modulated onto the RF carrier and provides the information to the RX processor 370.

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

[0075] At least one of TX processor 368, RX processor 356, and controller / processor 359 may be configured to perform aspects associated with Figure 1 the L2 reset receiving component 198.

[0076] At least one of TX processor 316, RX processor 370, and controller / processor 375 may be configured to perform aspects associated with Figure 1 the L2 reset indication component 199.

[0077] Figure 4 FIG. 400 is a diagram illustrating an exemplary cell configuration. As Figure 4 illustrated, a CU 402 (which may correspond to a component of a base station such as a gNB) may be associated with a first DU 404 (and other DUs). An L1 / L2 mobility configured cell set 406 may be associated with the first DU 404 and may include an L1 / L2 mobility active cell set 408 and an L1 / L2 mobility deactivated cell set 410. The L1 / L2 mobility configured cell set 406 may also include one or more cells that are not in the current L1 / L2 mobility active cell set 408 or the current L1 / L2 mobility deactivated cell set 410. For example, at a given time, the L1 / L2 mobility active cell set 408 may include a first subset of the L1 / L2 mobility configured cell set, and the L1 / L2 mobility deactivated cell set 410 may include a second non-overlapping subset of the L1 / L2 mobility configured cell set. One or more cells that are retained in the L1 / L2 mobility configured cell set may be outside the first set subset (e.g., active) or the second subset (e.g., deactivated). A UE 412 may use the cells in the L1 / L2 mobility active cell set 508 for data channel and control channel communication.

[0078] The UE 412 may be configured with a set of cells or cell groups for L1 / L2 triggered mobility (LTM). The UE 412 may receive an associated candidate RRC configuration for each candidate cell or cell group, which may be an RRC reconfiguration message or a cellgroupconfig message and other information elements (IEs). Candidate cells for LTM may be the current serving PCell, the current serving SCell, or a current non-serving cell. If the candidate cell for LTM is the current serving SCell, it may be activated or deactivated before performing LTM. After performing LTM, the UE 412 may switch to a target cell or target cell group. For the latter case, the UE will have switched to a target PCell and one or more SCells, each of which may be activated or deactivated.

[0079] The UE may be provided with a subset of L1 / L2 mobility deactivated cells (set of candidate cells), and the UE may autonomously choose to add this subset to the set of L1 / L2 mobility activated cells. For example, the UE may add a cell in the subset of L1 / L2 mobility deactivated cells to the set of L1 / L2 mobility activated cells based on measurements (e.g., measured channel quality), load, etc. In some aspects, each RU in the RU may have multi-component carrier (CC) (N CCs) support (where each CC is a cell). In some aspects, activation or deactivation may be performed for a carrier (cell) group.

[0080] A network node (e.g., a base station) may use an L3 handover (e.g., using RRC signaling) to change the cell for the UE. However, the L3 handover may be time-consuming and / or inefficient. Compared with the L3 (RRC)-based method, the network node may utilize an improved L1 / L2 signaling scheme to change one or more cells for the UE in a faster manner. For example, the UE may receive an L1 or L2 mobility cell configuration for a set of cells for L1 or L2 inter-cell mobility (e.g., L1 / L2 triggered mobility or LTM). The set of cells may include multiple cells, and each cell in the set of cells may be activated or deactivated to perform data and / or control transfer using L1 or L2 signaling. The UE may receive L1 or L2 signaling indicating multiple activated cells, and use the L1 or L2 signaling to activate one or more cells among the multiple activated cells in the priority order for data and / or control transfer.

[0081] Figure 5 FIG. 500 is a diagram illustrating the overall architecture of the NG-RAN. As Figure 5 shown, a central unit of the base station (BS-CU) (such as BS-CU 502) may correspond to a logical node hosting the RRC, SDAP, and PDCP protocols of the base station, which control the operation of one or more distributed units of the base station (BS-DU) (such as BS-DU 504, 506), as Figure 5 shown. The BS-CU 502 may terminate the F1 interfaces (e.g., F1 interfaces 514, 516) connected to the BS-DU 504, 506. BS-DUs such as BS-DU 504, 506 may correspond to logical nodes hosting the RLC, MAC, and PHY layers of the base station. The operation of the BS-DU may be controlled by the BS-CU. One BS-DU may support one or more cells, and one cell may be supported by only one BS-DU. The BS-DU may terminate the F1 interfaces (e.g., F1 interfaces 514, 516) connected to the BS-CU.

[0082] Wireless communication can adopt various mobility scenarios. In some scenarios, the serving cell can be changed through an L3 handover, and cell evaluation may be relatively slow (about 1 second). The L3 handover can incur a downtime of about 80 ms, and no data can pass during this period. In some scenarios, the UE can be connected to the serving cell to obtain control and data and potentially connected to an additional cell (non-serving cell) to obtain data. The non-serving cell can be changed using L1 / L2 signaling without downtime. If the reference signal received power (RSRP) of the serving cell is large enough (e.g., greater than a threshold) or the new serving cell is close enough to the old serving cell, no L3 handover is required when changing the serving cell. Otherwise, the UE can perform an L3 handover on the best available cell (and incur downtime). To reduce the time and signaling for inter-cell mobility, in some aspects, the serving cell can be changed using L1 / L2 signaling without involving an L3 handover. Therefore, when the serving cell changes, no downtime or reduced downtime will be incurred. The serving cell change using L1 / L2 signaling can be applicable to both intra-DU scenarios and inter-DU scenarios.

[0083] Figure 6 FIG. 600 is an illustration that exemplifies lower layer (e.g., L1 or L2) inter-cell mobility or L1 / L2-triggered mobility (LTM) examples. As Figure 6 shown, the UE 602 can be served by a serving cell (Cell 1 612) or by a cell group (e.g., CG1). The UE 602 can be configured with a set of cells as candidate cells for L1 / L2 mobility. The cell group can include, for example, Cell 2 614, Cell 3 616, and Cell 4 618, as Figure 6As shown. Although each example is described in connection with an individual cell, each aspect similarly applies to cell groups. For example, cell 2 614 may be cell group 2, cell 3 616 may be cell group 3, and / or cell 4 618 may be cell group 4. UE 602 may receive RRC configurations associated with cell 2614, cell 3 616, and cell 4 618. When the serving cell is changed to the target cell selected for handover, UE 602 may apply the associated RRC configuration of the target cell. UE 602 may perform measurements (e.g., L1 measurements) on candidate cells and may select the target cell based on the measurements. For example, UE 602 may provide a measurement report and receive a cell handover command via L1 / L2 signaling (e.g., Medium Access Control - Control Element (MAC-CE) or DCI). Thus, a set of candidate cells for L1 / L2 inter-cell mobility may be configured for the UE, and a subset of the candidate cells may be activated for the UE. The cells that are not activated (which may be referred to as deactivated cells in some aspects) are cells for which the UE receives L1 / L2 mobility configurations and for which the UE performs measurements but are not used for data or control transfer until they are activated. As the UE moves, cells from the set of L1 / L2 mobility configuration cells may be deactivated and activated by L1 / L2 signaling based on signal quality (e.g., based on measurements), load, etc. Example measurements may include cell coverage measurements represented by RSRP and quality represented by Radio Signal Receiving Quality (RSRQ), or other measurements performed by the UE on signals from the base station. In some aspects, these measurements may be L1 measurements, such as one or more of RSRP, RSRQ, Received Signal Strength Indicator (RSSI), or Signal-to-Interference-plus-Noise Ratio (SINR) measurements of various signals (such as SSB, PSS, SSS, Broadcast Channel (BCH), DM-RS, CSI-RS, etc.). The mechanisms for lower layer inter-cell mobility (e.g., LTM) apply to scenarios involving cell groups. For example, UE 602 may be served by a cell group (e.g., cell group 1 (CG1)) and configured with a set of candidate cell groups (e.g., CG2, CG3, CG4) for L1 / L2 mobility. UE 602 may switch the serving cell (or serving cell group) between candidate cell groups based on the same principles described above.

[0084] The configuration and maintenance of multiple candidate cells may allow for a faster application of the configuration for the candidate cells, and the active set of cells may provide for dynamic switching between candidate serving cells (e.g., including SpCell and SCell) based on L1 or L2 signaling.

[0085] When the UE performs an L3 handover, RRC signaling (e.g., L3 signaling) instructs the UE to perform an L2 reset, such as a MAC reset, an RLC reset, or a PDCP resume. In inter-cell mobility, the UE does not receive L3 signaling indicating the handover. Aspects presented herein enable the UE to determine whether to perform an L2 reset in response to inter-cell mobility triggered by L1 or L2 signaling.

[0086] Figure 7A And Figure 7B is a diagram illustrating L2 reset during lower layer mobility. Figure 7A is a diagram 700 illustrating L2 reset for in-DU mobility. As Figure 7A shown, the serving cell for UE 702 can originally be the source cell (e.g., cell 1 712), and the serving cell can be changed to the target cell (e.g., cell 2 714). Both cell 1 712 and cell 2 714 are served by the same DU (BS-DU1 720). Thus, when the serving cell is changed from cell 1 712 to cell 2 714, the RLC endpoints do not change. For this serving cell change, UE 702 can skip performing an L2 reset (e.g., resetting MAC or RLC, or resuming PDCP). Although the example is described for resetting MAC or RLC, in other aspects the UE can skip rebuilding MAC or skip rebuilding RLC. The UE can have multiple RLC entities corresponding to multiple logical channels. The reset or rebuild instruction can be selective, e.g., instructing the UE to perform a reset or rebuild action for one RLC entity but not another. For example, the UE can skip RLC reset / rebuild for a subset of RLC entities and can perform RLC reset / rebuild for another subset of RLC entities. Similarly, the UE can have multiple PDCP entities associated with different radio bearers of the UE, and PDCP resume can also be selective. For example, the UE can skip PDCP resume for one or more PDCP entities and can perform PDCP for other PDCP entities. Figure 7B is a diagram 750 illustrating L2 reset for inter-DU mobility. As Figure 7BAs shown, the serving cell for UE 752 can originally be the source cell (e.g., cell 1 762), and this serving cell can be changed to the target cell (e.g., cell 3 766). Cell 1 762 and cell 3 766 are served by different DUs respectively (e.g., BS-DU1 770 for cell 1 762 and BS-DU2 780 for cell 3 766). Therefore, when the serving cell is changed from cell 1 762 to cell 3 766, the RLC endpoint changes. For this serving cell change, UE752 can perform an L2 reset (e.g., MAC layer reset or reconstruction, RLC layer reset or reconstruction, or PDCP layer recovery).

[0087] Whether the UE needs to perform an L2 reset (e.g., MAC layer reset or reconstruction, RLC layer reset or reconstruction, or PDCP layer recovery) can depend on the target cell or cell group selected for mobility. Since the network architecture is transparent to the UE, the UE can determine whether to perform an L2 reset based on the configuration or signaling from the network. In one example, the cell handover command (e.g., MAC-CE or DCI) received and triggering the cell change on the source cell (e.g., Figure 7A cell 1 712 in Figure 7B or cell 1 762 in Figure 6 can indicate whether an L2 reset is required. For example, the UE can receive L1 (DCI) or L2 (MAC-CE) signaling indicating that the UE should switch to cell 2 714 and skip the L2 reset. The UE can receive L1 or L2 signaling indicating that the UE should switch to cell 3 766 and perform an L2 reset. As described in connection with

[0088] In some aspects, the overhead of the L2 indication (and the L3 indication for L2 reset) for L2 reset can be reduced, and the UE security can be further provided by configuring (in the L3 / RRC configuration for L1 / L2 inter-cell mobility) the conditions or information for L2 reset. The UE can use these conditions or information to determine whether to perform an L2 reset when a cell change is triggered by L1 / L2 signaling. By providing the L2 reset information in the security-protected L3 signaling, this information can have additional security not provided in the MAC-CE. Similarly, the MAC CE provides more dynamic signaling, however, the association between the cell and the DU can be fixed. Since the L2 reset can depend on whether the source cell and the target cell are under the same DU or different DUs (which can be fixed), the configuration in the RRC signaling can be used instead of the MAC-CE signaling.

[0089] For example, the target cell (e.g., Figure 7A cell 2 714 inFigure 7B The RRC configuration of cell 3 766) in can indicate whether L2 reset is required when selecting a target cell. When serving the UE on cell 1 (or cell group 1), the UE can receive candidate RRC configurations associated with a set of candidate cells or cell groups (in this example, cells 2, 3, and 4 (or cell groups 2, 3, and 4)). The candidate RRC configuration associated with cell 2 indicates no L2 reset, while the candidate RRC configurations of cells 3 and 4 are configured with L2 reset. If the UE receives a command to switch to an associated cell or cell group, the UE can apply the candidate RRC configuration.

[0090] However, this configuration can include additional signaling for supporting consecutive lower layer cell handovers. When the RRC configuration of the target cell is used to indicate whether L2 reset is required, the RRC configuration of the target cell may not be updated under every instance of lower layer mobility (otherwise, the RRC overhead would be similar to the RRC overhead of L3 mobility). In some aspects, the RRC configuration can indicate whether L2 reset is required or not depending on the source cell and the target cell or cell group in subsequent cell / cell group handovers following the RRC configuration.

[0091] Figure 8A is a diagram 800 illustrating consecutive lower layer cell handovers. As Figure 8A shown, the UE can initially be connected to cell 1 812 (source cell), and the UE can receive RRC configurations associated with potential target cells (e.g., cell 2 814, cell 3 816, and cell 4 818). The RRC configurations of the potential target cells can assume that cell 1 812 is the source cell. Thus, the configuration for cell 2 814 can indicate that no L2 reset is required (since the handover from cell 1 812 to cell 2 814 is intra-DU mobility), while the configurations for cell 3 816 and cell 4 818 can indicate that L2 reset is required (since the handover from cell 1 812 to cell 3 816 (or cell 4 818) is inter-DU mobility). After the UE switches the serving cell from cell 1 812 to one of the target cells, these configurations may become obsolete (for the purpose of indicating L2 reset) for the next serving cell handover. For example, as Figure 8AAs shown, if cell 4818 is the target cell in a serving cell handover (since it is assumed that cell 1812 is the source cell), the RRC configuration for cell 4818 may indicate that an L2 reset is required. However, if the UE performs two consecutive serving cell handovers: a first handover from cell 1812 to cell 3816 and a second handover from cell 3816 to cell 4818. When the UE performs the second serving cell handover, the RRC configuration for cell 4 becomes obsolete and does not provide an accurate indication regarding the L2 reset, because the execution of the L2 reset may be skipped when handing over from cell 3816 to cell 4818, since these cells are served by the same DU. Figure 8B FIG. 850 is a diagram illustrating another example of consecutive lower layer cell handovers. As Figure 8B shown, if cell 2864 is the target cell in a serving cell handover (since it is assumed that cell 1862 is the source cell), the RRC configuration for cell 2864 may indicate that an L2 reset is not required. However, if the UE performs two consecutive serving cell handovers: a first handover from cell 1862 to cell 3866 and a second handover from cell 3866 to cell 2864. When the UE performs the second serving cell handover, the RRC configuration for cell 2864 becomes obsolete and does not provide an accurate indication regarding the L2 reset, because the UE is to perform an L2 reset in response to handing over from cell 3866 to cell 2864, since these cells are served by different DUs.

[0092] The present disclosure provides methods and apparatuses for determining L2 resets in lower layer mobility in a manner that provides security and enables reduction of signaling overhead. These methods and apparatuses reduce communication overhead compared to L3 mobility and support consecutive serving cell handovers.

[0093] In one aspect of the present disclosure, the UE may receive an RRC configuration associated with a candidate target cell. For example, referring to Figure 6 , the candidate target cells may be cell 2614, cell 3616, and cell 4618, and the UE 602 may receive the RRC configurations associated with cell 2614, cell 3616, and cell 4618. Additionally, the UE may also receive, in the RRC, a grouping of cells (which may include candidate target cells and the current serving cell). The grouping may indicate one or more of the following: the association between each cell and each BS-DU, the association between each cell and each BS-CU, and the association between each cell and each TRP. For example, referring to Figure 6, the grouping of each cell may indicate that cell 1 812 and cell 2 814 are associated with the same DU (BS-DU1 620) and thus in the same first DU group, and cell 3 616 and cell 4 618 are associated with the same DU (BS-DU2 630) and thus in the same second DU group. In the present disclosure, cells in the same DU group (or CU group, TRP group) may be cells associated with the same DU (or CU, TRP). For example, referring to Figure 6 , cell 1 612 and cell 2 614 are in the same DU group because they are associated with the same BS-DU1 620, while cell 2 614 and cell 3 616 are in different DU groups because they are associated with different DUs.

[0094] The UE may determine whether to perform an L2 reset based on whether the source cell and the target cell are in the same group (e.g., DU group, CU group, or TRP group). For example, referring to Figure 6 , the grouping of the cells may indicate that cell 1 612 and cell 3 616 are in different DU groups. Therefore, when the UE 602 performs a serving cell handover to change the serving cell from cell 1 612 to cell 3 616, an L2 reset is required for this serving cell handover. After the serving cell is changed to cell 3 616, if the UE can perform a second serving cell handover to change the serving cell from cell 3 616 to, for example, cell 4 618, then an L2 reset is not required for the second serving cell handover because the grouping of each cell indicates that cell 3 616 and cell 4 618 are in the same DU group.

[0095] Depending on the grouping of each cell, the UE may further determine whether to perform a partial L2 reset or whether to perform a RACH based on whether the source cell and the target cell are in the same group or different groups. The UE may receive separate groupings, where the UE uses the first grouping to determine whether to perform a first action during mobility and uses the second grouping to determine whether to perform a second action during mobility. Actions performed by the UE refer to different examples such as L2 reset or reconstruction, PDCP recovery, RACH, etc. The UE may further determine which measurement configuration to apply based on whether the source cell and the target cell are in the same group or different groups.

[0096] The grouping for reset can be based on the cell group for L1 / L2 mobility cell group handover. For example, the UE may receive a grouping of cell groups, which may indicate that, for example, cell group 1 and cell group 2 are associated with the same first DU (or CU, TRP), and cell group 3 and cell group 4 are associated with the same second DU (or CU, TRP). Thus, cell group 1 and cell group 2 are in the first DU (or CU, TRP) group, while cell group 3 and cell group 4 are in the second DU (or CU, TRP) group. The UE may perform reset or any one of the above actions based on whether the source cell group and the target cell group of the handover are in the same DU (or CU, TRP) group or different DU (or CU, TRP) groups.

[0097] In some aspects, the UE may receive an indication in the target cell RRC configuration for each candidate target cell as to whether to perform L2 reset. L2 reset may include one or more of the following: MAC layer reset or re-establishment, RLC layer reset or re-establishment, or PDCP layer recovery. A description of MAC reset is provided, for example, in Section 5.12 of TS 38.321 v17.2.0, and may include any subset of the enumerated functions (e.g., including any one of the following: stop running one or more timers; set the NDI for all uplink HARQ processes to 0; set the NDI for all HARQ process IDs to 0; stop any ongoing random access procedure; discard the signaling contention-free random access resources; flush the Msg 3 buffer; flush the MSGA buffer; cancel the triggering of the scheduling request procedure, BSR procedure, power headroom report procedure, LBT failure, BFR, timing advance report procedure, recommended bit rate query procedure, configured uplink / sidelink grant confirmation, configured sidelink grant confirmation, desired guard symbol query, positioning measurement gap activation / deactivation request procedure, triggering of the SDT procedure; flush the soft buffers for all DL HARQ processes; for each DL HARQ process, consider the next received transmission for the TB as the first transmission; release any temporary C-RNTI; reset the BFI counter; reset the LBT counter and other aspects of MAC reset). A description of disposing of the re-established RLC entity can be found, for example, in Section 5.1 of TS 38.322 v17.1.0, and may include any subset of the enumerated functions (e.g., including any one of the following: discard all RLC SDUs, RLC SDU segmentation, and RLC PDUs; stop and reset all timers; and reset all state variables to their initial values and other aspects of RLC re-establishment). When the UE receives a cell handover command, the cell handover command may indicate whether to activate or deactivate or overwrite the RRC configuration for the target cell in whole or in part (e.g., do a full reset or a partial reset). For example, refer to Figure 6, the UE 602 may receive, in the RRC configuration for these cells, an indication of whether to perform an L2 reset (e.g., a MAC reset or other L2 reset) for each candidate target cell among the candidate target cells (i.e., cell 2 614, cell 3 616, and cell 4 618). When the UE 602 receives a cell handover command to, for example, hand over the serving cell from cell 1 612 to cell 2 614, the cell handover command may indicate whether to activate, deactivate, or overwrite in whole or in part the RRC configuration for cell 2 614.

[0098] In some aspects, the UE may perform a cell handover and apply the associated target cell configuration. The UE may further receive, on the target cell (via RRC or lower layer signaling), a separate indication of whether to perform an L2 reset, a partial reset, or no reset. For example, referring to Figure 6 , the UE 602 may receive, in the RRC configuration for these cells, the target cell configuration for each candidate target cell among the candidate target cells (i.e., cell 2 614, cell 3 616, and cell 4 618). When the UE 602 receives a cell handover command to, for example, hand over the serving cell from cell 1 612 to cell 2 614, the UE may hand over the serving cell to cell 2 614 and apply the associated configuration for cell 2 614. The UE may further receive, on cell 2 614 (via RRC or lower layer signaling), a separate indication of whether to perform an L2 reset, a partial reset, or no reset.

[0099] Figure 9 FIG. 900 is a call flow diagram illustrating a method of wireless communication according to various aspects of the present disclosure. Although aspects are described with respect to the base station 904, these aspects may be performed by the base stations in the aggregation and / or by one or more components of the base station 904 (e.g., the CU 110, the DU 130, and / or the RU 140).

[0100] As Figure 9 shown, at 906, the UE 902 may receive, from the base station 904, the configuration of multiple candidate cells for L1 or L2 inter-cell mobility. In some aspects, the configuration may be received via RRC. For example, referring to Figure 6 , the UE 602 may receive, from the base station, the configuration of multiple candidate cells for L1 or L2 inter-cell mobility. The multiple candidate cells may include cell 2 612, cell 3 616, and cell 4 618.

[0101] At 908, the UE 902 may receive, from the base station 904, information about L2 reset when switching between multiple candidate cells. In some aspects, the information about L2 reset may be a grouping of multiple candidate cells, which indicates the association of the candidate cells with the DU (or CU, TRP) of the base station. For example, referring toFigure 6 The grouping may indicate that cell 1 612 and cell 2 614 are associated with the same DU, and cell 3 616 and cell 4 618 are associated with the same DU.

[0102] At 910, UE 902 may receive one or more cell IDs or an indication of a cell ID from base station 904. In some aspects, the one or more cell IDs or the indication of a cell ID may respectively identify one or more target cells among a plurality of candidate cells for serving cell handover. In some aspects, UE 902 may receive the one or more cell IDs or the indication of a cell ID via a MAC-CE.

[0103] At 912, UE 902 may perform a serving cell handover within the candidate cells for UE 902 in response to L1 or L2 signaling. For example, referring to Figure 7A , UE 702 may perform a serving cell handover to change the serving cell from cell 1 712 to cell 2 714.

[0104] At 914, UE 902 may reset or reuse the L2 cell configuration in response to the serving cell handover and based on information. For example, referring to Figure 7A , the information received by UE 702 may indicate that the source cell and the target cell (i.e., cell 1 712 and cell 2 714) are in the same DU group. Thus, UE 702 may reuse the L2 cell configuration (i.e., no L2 reset is required). In another example, referring to Figure 7B , when the serving cell is changed from cell 1 762 to cell 3 766, the information received by UE 752 may indicate that the source cell and the target cell (i.e., cell 1 762 and cell 3 766) are in different DU groups. Thus, UE 752 may reset the L2 cell configuration. Although not illustrated, the UE may continue to perform subsequent cell handovers to different cells within the L1 / L2 inter-cell mobility candidate set configured for the UE, such as those described in conjunction with Figure 8A and Figure 8B .

[0105] In some aspects, a field ltm-NoResetID may be assigned to each LTM candidate configuration (e.g., the RRC configuration in 906) for a candidate cell group. A field ltm-ServingCellNoResetID may be assigned to the initial serving cell group configuration of the UE. During each LTM execution, the UE may check whether the ltm-ServingCellNoResetID of its current serving cell or cell group is the same as or different from the ltm-NoResetID of the target cell or cell group. If they are the same, no L2 reset is required. If they are different, the UE may perform an L2 reset. After the LTM execution, the UE may update the value of ltm-ServingCellNoResetID to the ltm-NoResetID of the new cell group. These steps may be repeated for each candidate LTM execution.

[0106] In some examples, the field ltm-NoResetID may indicate whether the UE should skip an L2 reset when performing an LTM cell handover procedure towards an LTM candidate. For example, if the value of ltm-NoResetID in the LTM candidate cell is the same as the value of ltm-ServingCellNoResetID in the serving cell of the cell group, the UE may not perform any L2 reset during the LTM cell handover procedure.

[0107] In some examples, the field ltm-ServingCellNoResetID may be used by the UE to determine whether an L2 reset can be performed when performing an LTM cell handover procedure towards an LTM candidate cell. For example, if the value of ltm-NoResetID in the LTM candidate cell is the same as the value of ltm-ServingCellNoResetID in the serving cell of the cell group, the UE may not perform any L2 reset during the LTM cell handover procedure.

[0108] Figure 10 FIG. 1000 is a flow chart illustrating a method for wireless communication at a UE in accordance with various aspects of the present disclosure. The method may be performed by the UE. The UE may be Figure 14 UE 104, 350, 702, 752, 902 or apparatus 1404 in a hardware implementation thereof. The method enables a single or consecutive serving cell handover through lower layer (e.g., L2) inter-cell mobility. Thus, it reduces the communication overhead when switching serving cells. Additionally, the security of wireless communication is improved by sending information related to serving cell handover via multiple indicators.

[0109] As Figure 10As shown, at 1002, the UE may receive, via RRC, a configuration of multiple candidate cells for L1 or L2 inter-cell mobility from a network entity. The network entity may be Figure 1 a base station or a component of a base station in an access network, or a core network component (e.g., base stations 102, 310; base station 904; or Figure 14 network entity 1402 in a hardware implementation of Figure 6 , Figure 7A , Figure 7B and Figure 9 illustrate various aspects of the steps in combination with flow chart 1000. For example, referring to Figure 9 , UE 902 may receive, at 906, via RRC, a configuration of multiple candidate cells for L1 or L2 inter-cell mobility from a network entity (base station 904). Referring to Figure 6 , the multiple candidate cells may include cell 2 614, cell 3 616, and cell 4 618. In one aspect, the multiple candidate cells may include cell 1 612. In some aspects, 1002 may be performed by L2 reset receiving component 198.

[0110] At 1004, the UE may receive, from the network entity, information about L2 reset when switching between multiple candidate cells. For example, referring to Figure 9 , UE 902 may receive, from a network entity (base station 904), information about L2 reset when switching between multiple candidate cells. In some aspects, 1004 may be performed by L2 reset receiving component 198.

[0111] At 1006, the UE may perform a serving cell handover within the candidate cells of the UE in response to L1 or L2 signaling. For example, referring to Figure 9 , at 912, UE 902 may perform a serving cell handover within the candidate cells of the UE in response to L1 or L2 signaling. In some aspects, 1006 may be performed by L2 reset receiving component 198.

[0112] At 1008, the UE may reset or reuse the L2 cell configuration in response to the serving cell handover and based on the information. For example, referring to Figure 9 , at 914, UE 902 may reset or reuse the L2 cell configuration in response to the serving cell handover and based on the information received by UE 902 at 908. In some aspects, 1008 may be performed by L2 reset receiving component 198.

[0113] Figure 11 is a flow chart 1100 illustrating a method for wireless communication at a UE according to various aspects of the present disclosure. The method may be performed by the UE. The UE may be Figure 14UE 104, 350, 702, 752, 902, or apparatus 1404 in the hardware specific implementation. The method achieves single or continuous serving cell handover through lower layer (e.g., L2) inter-cell mobility. Thus, it reduces the communication overhead when switching serving cells. Additionally, by sending information related to serving cell handover via multiple indications, the security of wireless communication is improved.

[0114] As Figure 11 shown, at 1102, the UE may receive, via RRC, a configuration of multiple candidate cells for L1 or L2 inter-cell mobility from a network entity. The network entity may be Figure 1 a base station or a component of a base station in the access network, or a core network component (e.g., base station 102, 310; base station 904; or Figure 14 network entity 1402 in the hardware specific implementation). Figure 6 , Figure 7A , Figure 7B and Figure 9 illustrate various aspects of the steps in combination with flowchart 1100. For example, referring to Figure 9 , UE 902 may receive, at 906, via RRC, a configuration of multiple candidate cells for L1 or L2 inter-cell mobility from a network entity (base station 904). Referring to Figure 6 , the multiple candidate cells may include cell 2 614, cell 3 616, and cell 4 618. In one aspect, the multiple candidate cells may include cell 1 612. In some aspects, 1102 may be performed by the L2 reset receiving component 198.

[0115] At 1104, the UE may receive, from the network entity, information about L2 reset when switching between multiple candidate cells. For example, referring to Figure 9 , UE 902 may receive, from a network entity (base station 904), information about L2 reset when switching between multiple candidate cells. In some aspects, 1104 may be performed by the L2 reset receiving component 198.

[0116] At 1108, the UE may perform a serving cell handover within the candidate cells of the UE in response to L1 or L2 signaling. For example, referring to Figure 9 , at 912, UE 902 may perform a serving cell handover within the candidate cells of the UE in response to L1 or L2 signaling. In some aspects, 1108 may be performed by the L2 reset receiving component 198.

[0117] At 1110, the UE may reset or reuse the L2 cell configuration in response to the serving cell handover and based on the information. For example, referring to Figure 9, at 914, the UE 902 may reset or reuse the L2 cell configuration in response to a serving cell handover and based on the information received by the UE 902 at 908. In some aspects, 1110 may be performed by the L2 reset receiving component 198.

[0118] In some aspects, according to one or more of the following, the information may include a grouping of multiple candidate cells and may include one or more cell groups of the multiple candidate cells: a first association of each candidate cell of the multiple candidate cells with one or more DUs of a network entity; a second association of each candidate cell of the multiple candidate cells with one or more CUs of the network entity; and a third association of each candidate cell of the multiple candidate cells with one or more TRPs of the network entity. For example, referring to Figure 6 , the information may include a grouping of multiple candidate cells (e.g., cell 2 614, cell 3 616, cell 4 618). The grouping of the multiple candidate cells may indicate that cell 1 612 and cell 2 614 are associated with the same DU (BS-DU1) and thus in the same DU group (the DU group for BS-DU1 620), and cell 3 616 and cell 4 618 are associated with the same DU (BS-DU2 630) and thus in the same DU group (the DU group for BS-DU2 630).

[0119] In some aspects, to perform a serving cell handover within a candidate cell for a UE, the UE may be configured to change one or more serving cells connected to the UE from one or more source cells to one or more target cells. The one or more source cells and the one or more target cells may be within the multiple candidate cells. For example, referring to Figure 7A , to perform a serving cell handover within a candidate cell for the UE702, the UE 702 may be configured to change one or more serving cells connected to the UE 702 from one or more source cells (cell 1 712) to one or more target cells (cell 2 714). The one or more source cells and the one or more target cells may be within the multiple candidate cells.

[0120] In some aspects, to reset or reuse the L2 cell configuration, the UE may be configured to: reset the L2 cell configuration of the UE in response to the one or more target cells and the one or more source cells being in different cell groups among one or more cell groups; or reuse the L2 cell configuration for the source cell of the UE in response to the one or more target cells and the one or more source cells being in the same cell group among one or more cell groups. For example, referring to Figure 7B, the UE 752 can be configured to: reset the L2 cell configuration of the UE in response to one or more target cells (cell 3 766) and one or more source cells (cell 1 762) being in different cell groups among one or more cell groups (cell 1 762 and cell 3 766 are in different DU groups). Refer to Figure 7A , the UE 702 can be configured to: reuse the L2 cell configuration for the source cell of the UE 702 in response to one or more target cells (cell 2 714) and one or more source cells (cell 1 712) being in the same cell group among one or more cell groups (cell 1 and cell 2 are in the same DU group).

[0121] In some aspects, to reset the L2 cell configuration of the UE, the UE can be configured to perform one or more of the following: MAC layer reset or reconstruction; RLC layer reset or reconstruction; or PDCP layer recovery. For example, refer to Figure 7B , when the UE 752 resets the L2 cell configuration, the UE 752 can be configured to perform one or more of the following: MAC layer reset or reconstruction; RLC layer reset or reconstruction; or PDCP layer recovery.

[0122] In some aspects, to change one or more serving cells connected to the UE, the UE can be further configured to: perform a partial L2 layer reset based on the grouping of one or more target cells and one or more source cells among a grouping of multiple candidate cells. For example, refer to Figure 9 , to change one or more serving cells connected to the UE 902, the UE 902 can be further configured to: perform a partial L2 layer reset based on the grouping of one or more target cells and one or more source cells among a grouping of multiple candidate cells (received by the UE 902 at 908).

[0123] In some aspects, to change one or more serving cells connected to the UE, the UE can be further configured to: perform a RACH procedure based on the grouping of one or more target cells and one or more source cells among a grouping of multiple candidate cells. For example, refer to Figure 9 , to change one or more serving cells connected to the UE 902, the UE 902 can be further configured to perform a RACH procedure based on the grouping of one or more target cells and one or more source cells among a grouping of multiple candidate cells (received by the UE 902 at 908).

[0124] In some aspects, to change one or more serving cells connected to the UE, the UE can be further configured to: select a measurement configuration for the UE based on the grouping of one or more target cells and one or more source cells among a grouping of multiple candidate cells. For example, refer to Figure 9, To change one or more serving cells connected to UE 902, UE 902 may be further configured to select a measurement configuration for UE 902 based on a grouping of one or more target cells and one or more source cells in a grouping of multiple candidate cells (received by UE 902 at 908).

[0125] In some aspects, at 1106, the UE may be configured to receive one or more cell IDs or indications of cell IDs from a network entity via MAC-CE or DCI. The one or more cell IDs or indications of cell IDs may respectively identify one or more target cells among the multiple candidate cells. For example, referring to Figure 9 , UE 902 may receive one or more cell IDs or indications of cell IDs from a network entity (base station 904) via MAC-CE or DCI at 910. In some examples, the indication of the cell ID may be an index of a configuration associated with one or more target cells. The one or more cell IDs or indications of cell IDs may respectively identify one or more target cells among the multiple candidate cells. In some aspects, 1106 may be performed by the L2 reset reception component 198.

[0126] In some aspects, at 1112, the information may include an indication in MAC-CE or DCI indicating whether to reset the L2 cell configuration in response to a serving cell handover. For example, referring to Figure 9 , the information (received by UE 902 at 908) may include an indication in MAC-CE or DCI indicating whether to reset the L2 cell configuration in response to a serving cell handover.

[0127] In some aspects, at 1114, the information may be included in an indication from the target cell. The indication may indicate whether to reset the L2 cell configuration for the target cell in response to a serving cell handover. For example, referring to Figure 7A , when UE 702 performs a serving cell handover to change the serving cell from cell 1 712 to cell 2 714, the information may be included in an indication from the target cell (cell 2 714). The indication may indicate whether to reset the L2 cell configuration for the target cell (cell 2 714) in response to a serving cell handover.

[0128] In some aspects, at 1116, the information may be based on the presence or absence of an indication from the target cell. The presence or absence of the indication may indicate whether to reset the L2 cell configuration for the target cell in response to a serving cell handover. For example, referring to Figure 7AWhen the UE 702 performs a serving cell handover to change the serving cell from cell 1 712 to cell 2 714, the information may be based on the presence or absence of an indication from the target cell (cell 2 714). The presence or absence of the indication may indicate whether to reset the L2 cell configuration for the target cell (cell 2 714) in response to the serving cell handover.

[0129] In some aspects, to reset or reuse the L2 cell configuration, the UE may be configured to: reuse the L2 cell configuration after a serving cell handover based on the absence of the indication; or reset the L2 cell configuration after a serving cell handover based on the presence of the indication. For example, referring to Figure 7A when the UE 702 performs a serving cell handover to change the serving cell from cell 1 712 to cell 2 714, the UE 702 may be configured to: reuse the L2 cell configuration after a serving cell handover based on the absence of the indication; or reset the L2 cell configuration after a serving cell handover based on the presence of the indication.

[0130] Figure 12 FIG. 1200 is a flowchart illustrating a method of wireless communication at a network entity according to various aspects of the present disclosure. The method may be performed by a network entity. The network entity may be Figure 1 a base station or a component of a base station in an access network, or a core network component (e.g., base stations 102, 310, 904; or Figure 14 the network entity 1402 in a hardware implementation of

[0131] As Figure 12 shown, at 1202, the network entity may send, via RRC, configurations of multiple candidate cells for L1 or L2 inter-cell mobility to the UE. The UE may be Figure 14 the UE 104, 350, 702, 752, 902 or the device 1404 in a hardware implementation of Figure 6 , Figure 7A , Figure 7B and Figure 9 illustrate various aspects of the steps in conjunction with the flowchart 1200. For example, referring to Figure 9 the network entity (base station 904) may send, via RRC, configurations of multiple candidate cells for L1 or L2 inter-cell mobility to the UE 902. Referring to Figure 6, multiple candidate cells may include cell 2 614, cell 3 616, and cell 4 618. In one aspect, the multiple candidate cells may include cell 1 612. In some aspects, 1202 may be performed by the L2 reset indication component 199.

[0132] At 1204, the network entity may send information about L2 reset to the UE when switching between multiple candidate cells, so that the UE performs a cell handover between the multiple candidate cells. For example, referring to Figure 9 , the network entity (base station 904) may send information about L2 reset to the UE 902 at 908 when switching between multiple candidate cells, so that the UE 902 performs a cell handover between the multiple candidate cells at 912. In some aspects, 1204 may be performed by the L2 reset indication component 199.

[0133] Figure 13 FIG. 1300 is a flowchart illustrating a method of wireless communication at a network entity according to various aspects of the present disclosure. The method may be performed by the network entity. The network entity may be Figure 1 a base station or a component of a base station in an access network, or a core network component (e.g., base stations 102, 310, 904; or Figure 14 the network entity 1402 in a hardware implementation of

[0134] As Figure 13 shown, at 1302, the network entity may send, via RRC, a configuration of multiple candidate cells for L1 or L2 inter-cell mobility to the UE. The UE may be Figure 14 the UE 104, 350, 702, 752, 902 or the device 1404 in a hardware implementation of Figure 6 , Figure 7A , Figure 7B and Figure 9 illustrate various aspects of the steps in combination with the flowchart 1300. For example, referring to Figure 9 , the network entity (base station 904) may send, via RRC, a configuration of multiple candidate cells for L1 or L2 inter-cell mobility to the UE 902. Referring to Figure 6 , the multiple candidate cells may include cell 2 614, cell 3 616, and cell 4 618. In one aspect, the multiple candidate cells may include cell 1 612. In some aspects, 1302 may be performed by the L2 reset indication component 199.

[0135] At 1304, a network entity may send information about L2 reset when switching between multiple candidate cells to the UE to cause the UE to perform a cell handover between the multiple candidate cells. For example, referring to Figure 9 , the network entity (base station 904) may send information about L2 reset when switching between multiple candidate cells to the UE 902 at 908 to cause the UE 902 to perform a cell handover between the multiple candidate cells at 912. In some aspects, 1304 may be performed by the L2 reset indication component 199.

[0136] In some aspects, the UE may perform a cell handover between multiple candidate cells by: performing a serving cell handover within a candidate cell for the UE in response to L1 or L2 signaling, and resetting or reusing the L2 cell configuration in response to the serving cell handover and based on the information. For example, referring to Figure 9 , at 914, the UE 902 may reset or reuse the L2 cell configuration in response to the serving cell handover and based on the information received by the UE 902 at 908.

[0137] In some aspects, according to one or more of the following, the information may include a grouping of multiple candidate cells and may include one or more cell groups of the multiple candidate cells: a first association of each candidate cell in the multiple candidate cells with one or more DUs of the network entity; a second association of each candidate cell in the multiple candidate cells with one or more CUs of the network entity; and a third association of each candidate cell in the multiple candidate cells with one or more TRPs of the network entity. For example, referring to Figure 6 , the information may include a grouping of multiple candidate cells (e.g., cell 2 614, cell 3 616, cell 4 618). The grouping of the multiple candidate cells may indicate that cell 1 612 and cell 2 614 are associated with the same DU (BS-DU1 620) and thus in the same DU group (the DU group for BS-DU1 620), and cell 3 616 and cell 4 618 are associated with the same DU (BS-DU2 630) and thus in the same DU group (the DU group for BS-DU2 630).

[0138] In some aspects, to perform a serving cell handover within a candidate cell for the UE, the UE may be configured to change one or more serving cells connected to the UE from one or more source cells to one or more target cells. The one or more source cells and the one or more target cells may be within the multiple candidate cells. For example, referring to Figure 7A, To perform a serving cell handover within a candidate cell for UE 702, UE 702 may be configured to change one or more serving cells connected to UE 702 from one or more source cells (Cell 1 712) to one or more target cells (Cell 2 714). The one or more source cells and the one or more target cells may be within multiple candidate cells.

[0139] In some aspects, to reset or reuse the L2 cell configuration, the UE may be configured to: reset the UE's L2 cell configuration in response to the one or more target cells and the one or more source cells being in different cell groups among one or more cell groups; or reuse the L2 cell configuration for the source cell used by the UE in response to the one or more target cells and the one or more source cells being in the same cell group among one or more cell groups. For example, referring to Figure 7B , UE 752 may be configured to: reset the UE's L2 cell configuration in response to the one or more target cells (Cell 3 766) and the one or more source cells (Cell 1 762) being in different cell groups among one or more cell groups (Cell 1 762 and Cell 3 766 are in different DU groups). Referring to Figure 7A , UE 702 may be configured to: reuse the L2 cell configuration for the source cell used by UE 702 in response to the one or more target cells (Cell 2 714) and the one or more source cells (Cell 1 712) being in the same cell group among one or more cell groups (Cell 1 712 and Cell 2 714 are in the same DU group).

[0140] In some aspects, to reset the UE's L2 cell configuration, the UE may be configured to perform one or more of the following: MAC layer reset or reconstruction; RLC layer reset or reconstruction; or PDCP layer recovery. For example, referring to Figure 7B , when UE 752 resets the L2 cell configuration, UE 752 may be configured to perform one or more of the following: MAC layer reset or reconstruction; RLC layer reset or reconstruction; or PDCP layer recovery.

[0141] In some aspects, to change one or more serving cells connected to the UE, the UE may be further configured to: perform a partial L2 layer reset based on the grouping of the one or more target cells and the one or more source cells within the grouping of multiple candidate cells. For example, referring to Figure 9 , to change one or more serving cells connected to UE 902, UE 902 may be further configured to: perform a partial L2 layer reset based on the grouping of the one or more target cells and the one or more source cells within the grouping of multiple candidate cells (received by UE 902 at 908).

[0142] In some aspects, to change one or more serving cells connected to a UE, the UE may be further configured to perform a RACH procedure based on a grouping of one or more target cells and one or more source cells among a grouping of multiple candidate cells. For example, referring to Figure 9 , to change one or more serving cells connected to UE 902, UE 902 may be further configured to perform a RACH procedure based on a grouping of one or more target cells and one or more source cells among a grouping of multiple candidate cells (received by UE 902 at 908).

[0143] In some aspects, to change one or more serving cells connected to a UE, the UE may be further configured to select a measurement configuration for the UE based on a grouping of one or more target cells and one or more source cells among a grouping of multiple candidate cells. For example, referring to Figure 9 , to change one or more serving cells connected to UE 902, UE 902 may be further configured to select a measurement configuration for UE 902 based on a grouping of one or more target cells and one or more source cells among a grouping of multiple candidate cells (received by UE 902 at 908).

[0144] In some aspects, at 1306, a network entity may be configured to send one or more cell IDs or an indication of a cell ID (e.g., an index of a configuration associated with a candidate cell) to the UE via a MAC-CE or DCI. The one or more cell IDs or the indication of a cell ID may respectively identify one or more target cells among the multiple candidate cells. For example, referring to Figure 9 , the network entity (base station 904) may send one or more cell IDs or an indication of a cell ID to UE 902 at 910 via a MAC-CE or DCI. In some examples, the indication of a cell ID may be an index of a configuration associated with one or more target cells. The one or more cell IDs or the indication of a cell ID may respectively identify one or more target cells among the multiple candidate cells. In some aspects, 1306 may be performed by the L2 reset indication component 199.

[0145] In some aspects, at 1308, the information may include an indication in a MAC-CE or DCI indicating whether to reset the L2 cell configuration in response to a serving cell handover. For example, referring to Figure 9 , the information (sent by base station 904 at 908) may include an indication in a MAC-CE or DCI indicating whether to reset the L2 cell configuration in response to a serving cell handover.

[0146] In some aspects, at 1310, the information may be included in an indication from the target cell. The indication may indicate whether to reset the L2 cell configuration for the target cell in response to a serving cell handover. For example, referring to Figure 7A , when the UE 702 performs a serving cell handover to change the serving cell from cell 1 712 to cell 2 714, the information may be included in an indication from the target cell (cell 2 714). The indication may indicate whether to reset the L2 cell configuration for the target cell (cell 2 714) in response to a serving cell handover.

[0147] In some aspects, at 1312, the information may be based on the presence or absence of an indication from the target cell. The presence or absence of the indication may indicate whether to reset the L2 cell configuration for the target cell in response to a serving cell handover. For example, referring to Figure 7A , when the UE 702 performs a serving cell handover to change the serving cell from cell 1 712 to cell 2 714, the information may be based on the presence or absence of an indication from the target cell (cell 2 714). The presence or absence of the indication may indicate whether to reset the L2 cell configuration for the target cell (cell 2 714) in response to a serving cell handover.

[0148] In some aspects, to reset or reuse the L2 cell configuration, the UE may be configured to: reuse the L2 cell configuration after a serving cell handover based on the absence of the indication; or reset the L2 cell configuration after a serving cell handover based on the presence of the indication. For example, referring to Figure 7A , when the UE 702 performs a serving cell handover to change the serving cell from cell 1 712 to cell 2 714, the UE 702 may be configured to: reuse the L2 cell configuration after a serving cell handover based on the absence of the indication; or reset the L2 cell configuration after a serving cell handover based on the presence of the indication.

[0149] Figure 14FIG. 1400 is a diagram illustrating an example of a hardware implementation for apparatus 1404. Apparatus 1404 may be a UE, a component of a UE, or may implement UE functionality. In some aspects, apparatus 1404 may include at least one cellular baseband processor 1424 (also referred to as a modem) coupled to one or more transceivers 1422 (e.g., cellular RF transceivers). The cellular baseband processor 1424 may include at least one on-chip memory 1424'. In some aspects, apparatus 1404 may also include one or more subscriber identity module (SIM) cards 1420 and at least one application processor 1406 coupled to a secure digital (SD) card 1408 and a screen 1410. The application processor 1406 may include on-chip memory 1406'. In some aspects, apparatus 1404 may also include a Bluetooth module 1412, a WLAN module 1414, an SPS module 1416 (e.g., GNSS module), one or more sensor modules 1418 (e.g., barometric pressure sensor / altimeter; motion sensors such as an inertial measurement unit (IMU), gyroscope, and / or accelerometer; light detection and ranging (LIDAR), radio assisted detection and ranging (RADAR), sound navigation and ranging (SONAR), magnetometer, audio, and / or other technologies for positioning), additional memory modules 1426, a power source 1430, and / or a camera 1432. The Bluetooth module 1412, the WLAN module 1414, and the SPS module 1416 may include on-chip transceivers (TRX) (or in some cases, only receivers (RX)). The Bluetooth module 1412, the WLAN module 1414, and the SPS module 1416 may include their own dedicated antennas and / or communicate using antenna 1480. The cellular baseband processor 1424 communicates with the UE 104 and / or with the RU associated with the network entity 1402 via the transceiver 1422 through one or more antennas 1480. The cellular baseband processor 1424 and the application processor 1406 may each separately include computer-readable media / memory 1424', 1406'. The additional memory module 1426 may also be considered computer-readable media / memory. Each computer-readable media / memory 1424', 1406', 1426 may be non-transitory. The cellular baseband processor 1424 and the application processor 1406 are each responsible for general processing, including execution of software stored on the computer-readable media / memory. The software, when executed by the cellular baseband processor 1424 / application processor 1406, causes the cellular baseband processor 1424 / application processor 1406 to perform the various functions described above. The cellular baseband processor 1424 and the application processor 1406 are configured to perform the various functions described above at least in part based on information stored in the memory.That is, the cellular baseband processor 1424 and the application processor 1406 can be configured to perform a first subset of the various functions described above without information stored in the memory, and can be configured to perform a second subset of the various functions described above based on information stored in the memory. The computer-readable medium / memory can also be used to store data manipulated by the cellular baseband processor 1424 / application processor 1406 when executing software. The cellular baseband processor 1424 / application processor 1406 can be components of the UE 350 and can include at least one 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 1404 can be at least one processor chip (modem and / or application) and include only the cellular baseband processor 1424 and / or the application processor 1406, while in another configuration, the device 1404 can be the entire UE (e.g., see Figure 3 the UE 350) and include additional modules of the device 1404.

[0150] As discussed above, the component 198 can be configured to: receive, via RRC, a configuration of a plurality of candidate cells for L1 or L2 inter-cell mobility from a network entity; receive information about L2 reset when switching between the plurality of candidate cells from the network entity; perform a serving cell handover within the candidate cell for the UE in response to L1 or L2 signaling; and reset or reuse the L2 cell configuration in response to the serving cell handover and based on the information. The component 198 can be further configured to perform any aspect of the aspects described in conjunction with Figure 10 the flowchart 1000 in Figure 11 and Figure 9Any aspect among the various aspects performed by the UE 902 in []. Component 198 may be within the cellular baseband processor 1424, the application processor 1406, or both the cellular baseband processor 1424 and the application processor 1406. Component 198 may be one or more hardware components specifically configured to perform the process / algorithm, implemented by one or more processors configured to perform the stated process / algorithm, stored in a computer-readable medium for implementation by one or more processors, or some combination thereof. When multiple processors are implemented, the multiple processors may perform the stated process / algorithm individually or in combination. As shown, the apparatus 1404 may include various components configured for various functions. In one configuration, the apparatus 1404 and particularly the cellular baseband processor 1424 and / or the application processor 1406 may include components for receiving, via RRC, a configuration of multiple candidate cells for L1 or L2 inter-cell mobility from a network entity, components for receiving information about L2 reset when switching between multiple candidate cells from the network entity, components for performing a serving cell handover within a candidate cell for the UE in response to L1 or L2 signaling, and components for resetting or reusing the L2 cell configuration in response to the serving cell handover and based on the information. The apparatus 1404 may also include components for performing aspects described in conjunction with Figure 10 the flowchart 1000 in [] and Figure 11 the flowchart 1100 in [], and / or any one of the aspects performed by the UE 902 in Figure 9 . The components may be the component 198 of the apparatus 1404 configured to perform the functions recited by the components. As described above, the apparatus 1404 may include a TX processor 368, an RX processor 356, and a controller / processor 359. Thus, in one configuration, the components may be the TX processor 368, the RX processor 356, and / or the controller / processor 359 configured to perform the functions recited by the components.

[0151] Figure 15FIG. 1500 is a diagram illustrating an example of a hardware implementation for network entity 1502. Network entity 1502 may be a BS, a component of a BS, or may implement BS functionality. Network entity 1502 may include at least one of CU 1510, DU 1530, or RU 1540. For example, depending on the layer functionality handled by component 199, network entity 1502 may include CU 1510; both CU 1510 and DU 1530; each of CU 1510, DU 1530, and RU 1540; DU 1530; both DU 1530 and RU 1540; or RU 1540. CU 1510 may include at least one CU processor 1512. CU processor 1512 may include on-chip memory 1512'. In some aspects, CU 1510 may also include additional memory modules 1514 and communication interface 1518. CU 1510 communicates with DU 1530 via an intermediate link such as the F1 interface. DU 1530 may include at least one DU processor 1532. DU processor 1532 may include on-chip memory 1532'. In some aspects, DU 1530 may also include additional memory modules 1534 and communication interface 1538. DU 1530 communicates with RU 1540 via a fronthaul link. RU 1540 may include at least one RU processor 1542. RU processor 1542 may include on-chip memory 1542'. In some aspects, RU 1540 may also include additional memory modules 1544, one or more transceivers 1546, antennas 1580, and communication interface 1548. RU 1540 communicates with UE 104. On-chip memories 1512', 1532', 1542' and additional memory modules 1514, 1534, 1544 may each be considered computer-readable media / memory. Each computer-readable media / memory may be non-transitory. Each of processors 1512, 1532, 1542 is responsible for general processing, including executing software stored on the computer-readable media / memory. The software, when executed by the corresponding processor, causes the processor to perform the various functions described above. The computer-readable media / memory may also be used to store data manipulated by the processor when executing the software.

[0152] As discussed above, component 199 can be configured to: send, via RRC, the configuration of multiple candidate cells for L1 or L2 inter-cell mobility to the UE; and send the UE information regarding L2 reset when switching between the multiple candidate cells, so that the UE performs cell switching between the multiple candidate cells. The UE can perform the cell switching by: performing a serving cell switch within the candidate cell for the UE in response to L1 or L2 signaling, and resetting or reusing the L2 cell configuration in response to the serving cell switch and based on the information. Component 199 can be further configured to perform any of the aspects described in conjunction with the flowchart 1200 in Figure 12 and the flowchart 1300 in Figure 13 and / or any of the aspects performed by the base station 904 in Figure 9 . Component 199 can be within one or more processors of one or more of the CU 1510, DU 1530, and RU 1540. Component 199 can be one or more hardware components specifically configured to perform the process / algorithm, implemented by one or more processors configured to perform the stated process / algorithm, stored in a computer-readable medium for implementation by one or more processors, or some combination thereof. When multiple processors are implemented, the multiple processors can perform the stated process / algorithm individually or in combination. The network entity 1502 can include various components configured for various functions. In one configuration, the network entity 1502 can include components for sending, via RRC, the configuration of multiple candidate cells for L1 or L2 inter-cell mobility to the UE, and components for sending the UE information regarding L2 reset when switching between multiple candidate cells so that the UE performs cell switching between the multiple candidate cells. The UE can perform the cell switching by: performing a serving cell switch within the candidate cell for the UE in response to L1 or L2 signaling, and resetting or reusing the L2 cell configuration in response to the serving cell switch and based on the information. The network entity 1502 can also include components for performing any of the aspects described in conjunction with the flowchart 1200 in Figure 12 and the flowchart 1300 in Figure 13 and / or any of the aspects performed by the base station 904 in Figure 9 . The components can be component 199 of the network entity 1502 configured to perform the functions recorded by the components. As described above, the network entity 1502 can include a TX processor 316, an RX processor 370, and a controller / processor 375. Thus, in one configuration, the components can be the TX processor 316, the RX processor 370, and / or the controller / processor 375 configured to perform the functions recorded by the components.

[0153] The present disclosure provides a method for wireless communication at a UE. The method may include: receiving, via RRC, a configuration of a plurality of candidate cells for L1 or L2 inter-cell mobility from a network entity; receiving, from the network entity, information regarding L2 reset when switching between the plurality of candidate cells; performing a serving cell handover within the candidate cells for the UE in response to L1 or L2 signaling; and resetting or reusing an L2 cell configuration in response to the serving cell handover and based on the information. The method enables a single or consecutive serving cell handover through lower layer (e.g., L2) inter-cell mobility. Thus, it reduces communication overhead when switching serving cells. Additionally, the security of wireless communication is improved by sending information related to serving cell handover via a plurality of indications.

[0154] It should be understood that the specific order or hierarchy of the blocks in the disclosed process / flowchart is merely illustrative of example methods. It should be understood that based on design preferences, the specific order or hierarchy of the blocks in the process / flowchart can be rearranged. Further, some blocks can be combined or omitted. The appended method claims present the elements of the various blocks in a sample order, but are not limited to the specific order or hierarchy given.

[0155] 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. Thus, the claims are not limited to the aspects described herein, but should be accorded the full scope consistent with the language of the claims. References to elements in the singular form do not, unless specifically stated otherwise, mean "one and only one" but rather "one or more." Terms such as "if," "when," and "while" do not imply a direct temporal relationship or reaction. That is, these phrases, such as "when...," do not imply an immediate action in response to the occurrence of an action or during the occurrence of an action, but simply imply that if the condition is met, then the action will occur, without requiring a specific or immediate time limit for the occurrence of the action. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or having an advantage over other aspects. Unless specifically stated otherwise, 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 "any combination of A, B, C, or any of them," including any combination of A, B, and / or C, may include multiple A's, multiple B's, or multiple C's. 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 "any combination of A, B, C, or any of them" can be only A, only B, only C, A and B, A and C, B and C, or A and B and C, where any such combination may contain one or more members of A, B, or C. A set should be construed as a collection of elements, where the number of elements is one or more. Thus, for a set of X, X will include one or more elements. When at least one processor is configured to execute a set of functions, the at least one processor is configured to execute the set of functions individually or in any combination. Thus, each processor in the at least one processor may be configured to execute a particular subset of the set of functions, where the subset is the complete set, a proper subset of the set, or an empty subset of the set. A processor may be referred to as a processor circuit. A memory / memory module may be referred to as a memory circuit. If a first device receives data from or sends data to a second device, the data may be received / sent directly between the first device and the second device, or indirectly between the first device and the second device through a collection of devices. A device configured to "output" or "provide" data (such as, send, signal, or message) may, for example, send the data with a transceiver, or may convey the data to a device that sends the data.A device configured to "obtain" data (such as a transmission, signal, or message) may, for example, receive the data with a transceiver or may obtain the data from a device that received the data. Information stored in a memory includes instructions and / or data. All structural and functional equivalents of elements of the various aspects described throughout this disclosure that are known or later will be known to a person of ordinary skill in the art are expressly incorporated herein by reference and are covered by the claims. Additionally, nothing disclosed herein is intended to be dedicated to the public, whether or not such disclosure is expressly recited in the claims. The words "module," "mechanism," "element," "device," etc. shall not be used in place of the word "component." Accordingly, no claim element shall be construed as a functional component unless the element is expressly recited using the phrase "component for...".

[0156] As used herein, the phrase "based on" should not be construed to refer 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 construed as "at least based on A" unless stated otherwise specifically.

[0157] The following aspects are merely illustrative and may be combined with other aspects or teachings described herein without limitation.

[0158] Aspect 1 is a method for wireless communication at a UE. The method includes: receiving, via RRC, a configuration of a plurality of candidate cells for L1 or L2 inter-cell mobility from a network entity; receiving, from the network entity, information regarding an L2 reset when switching between the plurality of candidate cells; performing, in response to L1 or L2 signaling, a serving cell handover within the candidate cells for the UE; and resetting or reusing an L2 cell configuration in response to the serving cell handover and based on the information.

[0159] Aspect 2 is the method according to aspect 1, wherein, according to one or more of the following, the information includes a grouping of the plurality of candidate cells and includes one or more cell groups of the plurality of candidate cells: a first association of each candidate cell of the plurality of candidate cells with one or more DUs of the network entity; a second association of each candidate cell of the plurality of candidate cells with one or more CUs of the network entity; and a third association of each candidate cell of the plurality of candidate cells with one or more TRPs of the network entity.

[0160] Aspect 3 is the method according to aspect 2, wherein performing the serving cell handover within the candidate cells for the UE includes: changing one or more serving cells connected to the UE from one or more source cells to one or more target cells, the one or more source cells and the one or more target cells being within the plurality of candidate cells. Resetting or reusing the L2 cell configuration includes: resetting the L2 cell configuration of the UE in response to the one or more target cells and the one or more source cells being in different cell groups among the one or more cell groups; or reusing the L2 cell configuration for the source cell of the UE in response to the one or more target cells and the one or more source cells being in the same cell group among the one or more cell groups.

[0161] Aspect 4 is the method according to any one of aspects 1 to 3, wherein resetting the L2 cell configuration of the UE includes one or more of the following: MAC layer reset or reconstruction; RLC layer reset or reconstruction; and PDCP layer recovery.

[0162] Aspect 5 is the method according to any one of aspects 3 to 4, wherein changing the one or more serving cells connected to the UE further includes: performing a partial L2 layer reset based on the grouping of the one or more target cells and the one or more source cells within the grouping of the plurality of candidate cells.

[0163] Aspect 6 is the method according to any one of aspects 3 to 4, wherein changing the one or more serving cells connected to the UE further includes: performing a RACH procedure based on the grouping of the one or more target cells and the one or more source cells within the grouping of the plurality of candidate cells.

[0164] Aspect 7 is the method according to any one of aspects 3 to 4, wherein changing the one or more serving cells connected to the UE further includes: selecting a measurement configuration for the UE based on the grouping of the one or more target cells and the one or more source cells within the grouping of the plurality of candidate cells.

[0165] Aspect 8 is the method according to any one of aspects 3 to 7, wherein the method further includes: receiving, from a network entity, one or more cell IDs or an indication of cell IDs via a MAC-CE or DCI, wherein the one or more cell IDs or the indication of cell IDs respectively identify the one or more target cells among the plurality of candidate cells.

[0166] Aspect 9 is the method according to any one of aspects 1 to 8, wherein the information includes an indication in a MAC-CE or DCI indicating whether to reset the L2 cell configuration in response to the serving cell handover.

[0167] Aspect 10 is the method according to any one of Aspects 1 to 8, wherein the information is included in an indication from the target cell. The indication indicates whether to reset the L2 cell configuration for the target cell in response to the serving cell handover.

[0168] Aspect 11 is the method according to any one of Aspects 1 to 8, wherein the information is based on the presence or absence of an indication from the target cell. The presence or absence of the indication indicates whether to reset the L2 cell configuration for the target cell in response to the serving cell handover.

[0169] Aspect 12 is the method according to Aspect 11, wherein resetting or reusing the L2 cell configuration includes: reusing the L2 cell configuration after the serving cell handover based on the absence of the indication; or resetting the L2 cell configuration after the serving cell handover based on the presence of the indication.

[0170] Aspect 13 is an apparatus for wireless communication at a UE, the apparatus including: at least one memory; and at least one processor, the at least one processor being coupled to the at least one memory and being configured to cause the UE to perform the method according to any one of Aspects 1 to 12, at least in part based on information stored in the at least one memory, the at least one processor being configured alone or in any combination.

[0171] Aspect 14 is the apparatus for wireless communication at a UE, including components for performing each step of the method according to any one of Aspects 1 to 12.

[0172] Aspect 15 is the apparatus according to any one of Aspects 13 to 14, further including a transceiver configured to receive or transmit in association with the method according to any one of Aspects 1 to 12.

[0173] Aspect 16 is a computer-readable medium (e.g., a non-transitory computer-readable medium) storing computer-executable code at a UE, wherein the code causes the UE to perform the method according to any one of Aspects 1 to 12 when executed by at least one processor.

[0174] Aspect 17 is a method for wireless communication at a network entity. The method includes: sending, via RRC, a configuration of a plurality of candidate cells for L1 or L2 inter-cell mobility to a UE; and sending information about L2 reset when switching between the plurality of candidate cells to the UE, so that the UE performs a cell handover between the plurality of candidate cells. The cell handover includes: performing a serving cell handover within the candidate cells for the UE in response to L1 or L2 signaling, and resetting or reusing an L2 cell configuration based on the information in response to the serving cell handover.

[0175] Aspect 18 is the method according to aspect 17, wherein, according to one or more of the following, the information includes a grouping of the plurality of candidate cells and includes one or more cell groups of the plurality of candidate cells: a first association of each candidate cell in the plurality of candidate cells with one or more DUs of the network entity; a second association of each candidate cell in the plurality of candidate cells with one or more CUs of the network entity; and a third association of each candidate cell in the plurality of candidate cells with one or more TRPs of the network entity.

[0176] Aspect 19 is the method according to aspect 18, wherein performing the serving cell handover within the candidate cells for the UE includes: changing one or more serving cells connected to the UE from one or more source cells to one or more target cells, the one or more source cells and the one or more target cells being within the plurality of candidate cells. Resetting or reusing the L2 cell configuration includes: resetting the L2 cell configuration of the UE in response to the one or more target cells and the one or more source cells being in different cell groups among the one or more cell groups; or reusing the L2 cell configuration for the source cell for the UE in response to the one or more target cells and the one or more source cells being in the same cell group among the one or more cell groups.

[0177] Aspect 20 is the method according to any one of aspects 17 to 19, wherein resetting the L2 cell configuration of the UE includes one or more of the following: MAC layer reset or reconstruction; RLC layer reset or reconstruction; or PDCP layer recovery.

[0178] Aspect 21 is the method according to any one of aspects 19 to 20, wherein the information instructs the UE to perform a partial L2 layer reset in the grouping of the plurality of candidate cells based on the grouping of the one or more target cells and the one or more source cells when changing the one or more serving cells connected to the UE.

[0179] Aspect 22 is the method according to any one of Aspects 19 to 20, wherein the information indicates that when the UE changes one or more serving cells connected to the UE, the UE performs a RACH procedure based on a group of the one or more target cells and a group of the one or more source cells among the groups of the plurality of candidate cells.

[0180] Aspect 23 is the method according to any one of Aspects 19 to 20, wherein the information indicates that when the UE changes one or more serving cells connected to the UE, the UE selects a measurement configuration for the UE based on a group of the one or more target cells and a group of the one or more source cells among the groups of the plurality of candidate cells.

[0181] Aspect 24 is the method according to any one of Aspects 19 to 23, wherein the method further includes: sending one or more cell IDs or an indication of a cell ID to the UE via a MAC-CE or DCI, where the one or more cell IDs or the indication of a cell ID respectively identify the one or more target cells among the plurality of candidate cells.

[0182] Aspect 25 is the method according to any one of Aspects 17 to 24, wherein the information includes an indication in a MAC-CE or DCI indicating whether to reset the L2 cell configuration in response to the serving cell handover.

[0183] Aspect 26 is the method according to any one of Aspects 17 to 24, wherein the information is included in an indication from a target cell. The indication indicates whether to reset the L2 cell configuration for the target cell in response to the serving cell handover.

[0184] Aspect 27 is the method according to any one of Aspects 17 to 24, wherein the information is based on the presence or absence of an indication from a target cell. The presence or absence of the indication indicates whether to reset the L2 cell configuration for the target cell in response to the serving cell handover.

[0185] Aspect 28 is the method according to Aspect 27, wherein resetting or reusing the L2 cell configuration includes: reusing the L2 cell configuration after the serving cell handover based on the absence of the indication; or resetting the L2 cell configuration after the serving cell handover based on the presence of the indication.

[0186] Aspect 29 is an apparatus for wireless communication at a network entity, the apparatus comprising: at least one memory; and at least one processor coupled to the at least one memory and configured to cause the network entity to perform, alone or in any combination, the method according to any one of aspects 17 to 28, at least in part based on information stored in the at least one memory.

[0187] Aspect 30 is the apparatus for wireless communication at a network entity, comprising means for performing each step of the method according to any one of aspects 17 to 28.

[0188] Aspect 31 is the apparatus according to any one of aspects 29 to 30, further comprising a transceiver configured to receive or transmit in association with the method according to any one of aspects 17 to 28.

[0189] Aspect 32 is a computer-readable medium (e.g., a non-transitory computer-readable medium) storing computer-executable code at a network entity, wherein the code, when executed by at least one processor, causes the network entity to perform the method according to any one of aspects 17 to 28.

Claims

1. An apparatus for wireless communication at a User Equipment (UE), the apparatus comprises: at least one memory; and at least one processor coupled to the at least one memory, and at least partially based on stored information stored in the at least one memory, the at least one processor is configured, alone or in any combination, to cause the UE to: receive, via Radio Resource Control (RRC), a configuration of a plurality of candidate cells for layer 1 (L1) or layer 2 (L2) inter-cell mobility from a network entity; receive, from the network entity, information regarding L2 reset when switching between the plurality of candidate cells; perform a serving cell handover within the plurality of candidate cells for the UE in response to L1 or L2 signaling; and reset or reuse the L2 cell configuration in response to the serving cell handover and based on the information.

2. The apparatus according to claim 1, wherein the information regarding the L2 reset when switching between the plurality of candidate cells in response to the L1 or L2 signaling is included in the RRC configuration.

3. The apparatus according to claim 2, wherein the RRC configuration indicates whether the L2 reset is to be performed depending on the source cell and the target cell for the serving cell handover.

4. The apparatus according to claim 1, the apparatus further comprises a transceiver coupled to the at least one processor, wherein, to receive the information regarding the L2 reset, the at least one processor is configured, alone or in any combination, to cause the UE to receive the information regarding the L2 reset via the transceiver.

5. The apparatus according to claim 1, wherein according to one or more of the following, the information includes a grouping of the plurality of candidate cells and includes one or more cell groups of the plurality of candidate cells: a first association of each candidate cell in the plurality of candidate cells with one or more distributed units (DUs) of the network entity; a second association of each candidate cell in the plurality of candidate cells with one or more centralized units (CUs) of the network entity; and a third association of each candidate cell in the plurality of candidate cells with one or more transmit receive points (TRPs) of the network entity.

6. The apparatus according to claim 5, wherein, to perform the serving cell handover within the plurality of candidate cells for the UE, the at least one processor is configured, alone or in any combination, to cause the UE to: change one or more serving cells connected to the UE from one or more source cells to one or more target cells, the one or more source cells and the one or more target cells being within the plurality of candidate cells, and wherein, to reset or reuse the L2 cell configuration, the at least one processor is configured, alone or in any combination, to: reset the L2 cell configuration of the UE in response to the one or more target cells and the one or more source cells being in different cell groups among the one or more cell groups; or Reuse the L2 cell configuration for the source cell for the UE in response to the one or more target cells and the one or more source cells being in the same cell group among the one or more cell groups.

7. The apparatus according to claim 6, wherein to reset the L2 cell configuration of the UE, the at least one processor is configured, alone or in any combination, to cause the UE to perform one or more of the following: Medium Access Control (MAC) layer reset or reconstruction; Radio Link Control (RLC) layer reset or reconstruction; or Packet Data Convergence Protocol (PDCP) layer recovery.

8. The apparatus according to claim 6, wherein to change the one or more serving cells connected to the UE, the at least one processor is further configured, alone or in any combination, to cause the UE to: Perform a partial L2 layer reset based on the packets of the one or more target cells and the one or more source cells among the packets of the plurality of candidate cells.

9. The apparatus according to claim 6, wherein to change the one or more serving cells connected to the UE, the at least one processor is further configured, alone or in any combination, to cause the UE to: Perform a Random Access Channel (RACH) procedure based on the packets of the one or more target cells and the one or more source cells among the packets of the plurality of candidate cells.

10. The apparatus according to claim 6, wherein to change the one or more serving cells connected to the UE, the at least one processor is further configured, alone or in any combination, to cause the UE to: Select a measurement configuration for the UE based on the packets of the one or more target cells and the one or more source cells among the packets of the plurality of candidate cells.

11. The apparatus according to claim 6, wherein the at least one processor is further configured, alone or in any combination, to cause the UE to: Receive one or more cell IDs or an indication of a cell ID from the network entity via Medium Access Control - Control Element (MAC-CE) or Downlink Control Information (DCI), wherein the one or more cell IDs or the indication of the cell ID respectively identify the one or more target cells among the plurality of candidate cells.

12. The apparatus according to claim 1, wherein the information includes an indication in Medium Access Control - Control Element (MAC-CE) or Downlink Control Information (DCI) indicating whether to reset the L2 cell configuration in response to the serving cell handover.

13. The apparatus according to claim 1, wherein the information is included in an indication from a target cell, the indication indicating whether to reset the L2 cell configuration for the target cell in response to the serving cell handover.

14. The apparatus according to claim 1, wherein the information is based on the presence or absence of an indication from a target cell, and the presence or absence of the indication indicates whether to reset the L2 cell configuration for the target cell in response to a handover from the serving cell. Wherein, To reset or reuse the L2 cell configuration, the at least one processor is configured, alone or in any combination, to cause the UE to: Reuse the L2 cell configuration after a handover from the serving cell based on the absence of the indication; or Reset the L2 cell configuration after a handover from the serving cell based on the presence of the indication.

15. An apparatus for wireless communication at a network entity, the apparatus comprises: At least one memory; and At least one processor, the at least one processor being coupled to the at least one memory and being configured, at least in part based on stored information stored in the at least one memory, alone or in any combination, to cause the network entity to: Send, via radio resource control (RRC), configurations of a plurality of candidate cells for layer 1 (L1) or layer 2 (L2) inter-cell mobility to a user equipment (UE); And Send information about L2 reset when switching between the plurality of candidate cells to the UE to cause the UE to perform a cell handover between the plurality of candidate cells, the cell handover including: Responsive to a serving cell handover within the plurality of candidate cells of the UE in response to L1 or L2 signaling, and Responsive to the serving cell handover and based on the information, resetting or reusing the L2 cell configuration.

16. The apparatus according to claim 15, wherein the information about the L2 reset when switching between the plurality of candidate cells in response to the L1 or L2 signaling is included in an RRC configuration.

17. The apparatus according to claim 16, wherein the RRC configuration indicates whether the L2 reset is to be performed depending on a source cell and a target cell for the serving cell handover.

18. The apparatus according to claim 15, the apparatus further comprising a transceiver coupled to the at least one processor, wherein, To send the information about the L2 reset, the at least one processor is configured, alone or in any combination, to cause the network entity to send the information about the L2 reset via the transceiver.

19. The apparatus according to claim 15, wherein the information includes a grouping of the plurality of candidate cells and includes one or more cell groups of the plurality of candidate cells according to one or more of the following: A first association of each candidate cell in the plurality of candidate cells with one or more distributed units (DUs) of the network entity; A second association of each candidate cell in the plurality of candidate cells with one or more centralized units (CUs) of the network entity; and A third association of each candidate cell in the plurality of candidate cells with one or more transmit receive points (TRPs) of the network entity.

20. The apparatus according to claim 19, wherein the serving cell handover among the plurality of candidate cells for the UE comprises: a change of one or more serving cells connected to the UE from one or more source cells to one or more target cells, the one or more source cells and the one or more target cells being within the plurality of candidate cells, and wherein the information instructs the UE: to reset the L2 cell configuration of the UE in response to the one or more target cells and the one or more source cells being in different cell groups among the one or more cell groups; or to reuse the L2 cell configuration for the source cell of the UE in response to the one or more target cells and the one or more source cells being in the same cell group among the one or more cell groups.

21. The apparatus according to claim 20, wherein resetting the L2 cell configuration of the UE comprises one or more of the following: Media Access Control (MAC) layer reset or reconstruction; Radio Link Control (RLC) layer reset or reconstruction; or Packet Data Convergence Protocol (PDCP) layer recovery.

22. The apparatus according to claim 20, wherein the at least one processor is further configured, alone or in any combination, to cause the network entity: to send, via Media Access Control - Control Element (MAC - CE) or Downlink Control Information (DCI), one or more cell IDs or an indication of a cell ID to the UE, wherein the one or more cell IDs or the indication of the cell ID respectively identify the one or more target cells among the plurality of candidate cells.

23. The apparatus according to claim 15, wherein the information comprises an indication in Media Access Control - Control Element (MAC - CE) or Downlink Control Information (DCI) indicating whether to reset the L2 cell configuration in response to the serving cell handover.

24. The apparatus according to claim 15, wherein the information is included in an indication from a target cell, the indication indicating whether to reset the L2 cell configuration for the target cell in response to the serving cell handover.

25. The apparatus according to claim 15, wherein the information is based on the presence or absence of an indication from a target cell, the presence or absence of the indication indicating whether to reset the L2 cell configuration for the target cell in response to the serving cell handover.

26. The apparatus according to claim 25, wherein resetting or reusing the L2 cell configuration comprises: reusing the L2 cell configuration after the serving cell handover based on the absence of the indication; or resetting the L2 cell configuration after the serving cell handover based on the presence of the indication.

27. A method for wireless communication at a user equipment (UE), the method comprises: receiving, via Radio Resource Control (RRC), a configuration of a plurality of candidate cells for layer 1 (L1) or layer 2 (L2) inter - cell mobility from a network entity; Receive information about L2 reset when switching between the multiple candidate cells from the network entity; Perform a serving cell handover within the multiple candidate cells for the UE in response to L1 or L2 signaling; And Reset or reuse the L2 cell configuration in response to the serving cell handover and based on the information.

28. The method according to claim 27, wherein the information includes a grouping of the multiple candidate cells and includes one or more cell groups of the multiple candidate cells according to one or more of the following: A first association of each candidate cell in the multiple candidate cells with one or more distributed units (DUs) of the network entity; A second association of each candidate cell in the multiple candidate cells with one or more centralized units (CUs) of the network entity; and A third association of each candidate cell in the multiple candidate cells with one or more transmit receive points (TRPs) of the network entity.

29. A method for wireless communication at a network entity, the method comprises: Send configurations of multiple candidate cells for layer 1 (L1) or layer 2 (L2) inter-cell mobility to a user equipment (UE) via radio resource control (RRC); And Send information about L2 reset when switching between the multiple candidate cells to the UE, so that the UE performs a cell handover between the multiple candidate cells, including: Perform a serving cell handover within the multiple candidate cells for the UE in response to L1 or L2 signaling; And Reset or reuse the L2 cell configuration in response to the serving cell handover and based on the information.

30. The method according to claim 29, wherein the information includes a grouping of the multiple candidate cells and includes one or more cell groups of the multiple candidate cells according to one or more of the following: A first association of each candidate cell in the multiple candidate cells with one or more distributed units (DUs) of the network entity; A second association of each candidate cell in the multiple candidate cells with one or more centralized units (CUs) of the network entity; and A third association of each candidate cell in the multiple candidate cells with one or more transmit receive points (TRPs) of the network entity.

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