Method and apparatus for lower layer triggered mobility in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. The UE comprises a transceiver configured to receive a Radio Resource Control (RRC) reconfiguration message comprising a configuration for at least one lower layer triggered Mobility (LTM) candidate cells, and to receive an LTM handover command Media Access Control (MAC) Control Element (CE) indicating to perform an LTM cell handover to an LTM candidate cell of the at least one LTM candidate cell. The transceiver is further configured to transmit a random access (RA) preamble for a number of repetitions N to the LTM candidate cell indicated by the MAC CE. The UE also includes a processor operably coupled to the transceiver. The processor is configured to listen for a physical downlink control channel (PDCCH) for a random access response after the RA preamble has been transmitted N times.

Description

Technical Field

[0001] This disclosure generally relates to wireless networks, wireless communication systems, or mobile communication systems. More specifically, this disclosure relates to lower-layer triggered mobility in wireless communication systems. Background Technology

[0002] 5G mobile communication technology defines a wide frequency band, enabling high transmission rates and new services. It can be implemented not only in the "sub-6 GHz" band, such as 3.5 GHz, but also in the "above 6 GHz" band, including 28 GHz and 39 GHz, known as millimeter wave (mmWave). Furthermore, to achieve transmission rates 50 times faster than 5G and ultra-low latency one-tenth that of 5G, implementation of 6G mobile communication technology (referred to as "super 5G systems") in terahertz bands (e.g., the 95 GHz to 3 THz band) has been considered.

[0003] In the early stages of 5G mobile communication technology development, to support services and meet performance requirements related to enhanced Mobile Broadband (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), standardization has been underway for the following: beamforming and massive MIMO to mitigate radio wave path loss and increase radio wave transmission distance in millimeter waves; support for basic parameter sets (e.g., operating multiple subcarrier spacings) for efficient utilization of millimeter wave resources and dynamic operation of time slot formats; initial access technologies to support multi-beam transmission and broadband; definition and operation of the Bandwidth Part (BWP); new channel coding methods, such as low-density parity-check (LDPC) codes for large-scale data transmission and polar codes for highly reliable transmission of control information; L2 preprocessing; and network slicing to provide dedicated networks for specific services.

[0004] Currently, given the services that 5G mobile communication technology will support, discussions are underway regarding improvements and performance enhancements to the initial 5G mobile communication technology, and physical layer standardization already exists for technologies such as: Vehicle-to-everything (V2X), used to assist autonomous vehicles in determining driving based on information sent by the vehicle about its location and status, and to enhance user convenience; New Radio Unlicensed (NR-U), for system operation in compliance with various regulatory requirements in unlicensed frequency bands; NR UE power saving; Non-Terrestrial Network (NTN), which is UE-satellite direct communication used to provide coverage in areas where communication with terrestrial networks is unavailable; and positioning.

[0005] Furthermore, standardization is underway in air interface architecture / protocols for technologies such as: Industrial Internet of Things (IIoT) to support new services through interoperability and convergence with other industries; Integrated Access and Backhaul (IAB) to provide nodes for network service area extension by supporting radio backhaul and access links in an integrated manner; mobility enhancements, including conditional handover and Dual Active Protocol Stack (DAPS) handover; and two-step random access to simplify random access procedures (2-step RACH for NR). Standardization is also underway in system architecture / services for: 5G baseline architecture (e.g., service-based architecture or service-based interface) to combine Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies; and Mobile Edge Computing (MEC) for receiving services based on UE location.

[0006] With the commercialization of 5G mobile communication systems, the already exponentially growing number of connected devices will connect to the communication network. Accordingly, enhanced functionality and performance of 5G mobile communication systems, as well as the integrated operation of connected devices, are expected to be necessary. To this end, new research is planned related to the following: extended reality (XR) for effectively supporting augmented reality (AR), virtual reality (VR), mixed reality (MR), etc.; improving 5G performance and reducing complexity by leveraging artificial intelligence (AI) and machine learning (ML); AI service support; metaverse service support; and drone communication.

[0007] Furthermore, this development of 5G mobile communication systems will not only serve as the foundation for developing new waveforms for providing terahertz band coverage for 6G mobile communication technologies, multi-antenna transmission technologies (such as full-dimensional MIMO (FD-MIMO), array antennas, and massive MIMO), metamaterial-based lenses and antennas for improving terahertz band signal coverage, high-dimensional spatial multiplexing technologies using orbital angular momentum (OAM), and reconfigurable intelligent surfaces (RIS), but also as the foundation for developing full-duplex technologies to improve the frequency efficiency of 6G mobile communication technologies and improve system networks, AI-based communication technologies to implement system optimization by leveraging satellites and artificial intelligence (AI) from the design stage and internalizing end-to-end AI support capabilities, and next-generation distributed computing technologies to implement services with complexity exceeding the limits of UE operational capabilities by utilizing ultra-high-performance communication and computing resources. Summary of the Invention

[0008] Technical issues

[0009] The demand for wireless data services is growing rapidly due to the increasing popularity of smartphones and other mobile data devices (such as tablets, notebook computers, netbooks, e-book readers, and machine-type devices) among consumers and businesses. To meet this high growth in mobile data services and support new applications and deployments, improvements in radio interface efficiency and coverage are paramount.

[0010] To meet the increased demand for wireless data traffic since the deployment of 4G communication systems, and to enable various vertical applications, 5G communication systems have been developed and are currently being deployed. Enabling technologies for 5G / NR mobile communication include: massive MIMO technology, moving from traditional cellular bands to higher frequency bands to provide beamforming gain and support greater capacity; new waveforms (such as new Radio Access Technologies (RATs)) to flexibly adapt to various services / applications with different needs; new multiple access schemes to support massive connectivity, and so on.

[0011] Solution to the problem

[0012] This disclosure provides apparatus and methods for lower-level mobility in wireless communication systems.

[0013] In one embodiment, a user equipment (UE) is provided. The UE includes a transceiver configured to receive a Radio Resource Control (RRC) reconfiguration message including a configuration for at least one lower-layer triggered Mobility (LTM) candidate cell, and to receive an LTM handover command Media Access Control (MAC) control element (CE) instructing the execution of an LTM cell handover from at least one LTM candidate cell to another. The transceiver is also configured to transmit a random access (RA) preamble to the LTM candidate cell indicated by the MAC CE up to a repetition count N. The UE also includes a processor operatively coupled to the transceiver. The processor is configured to listen to the Physical Downlink Control Channel (PDCCH) in response to the random access response after the RA preamble has been transmitted N times.

[0014] In another embodiment, a base station (BS) is provided. The BS includes a processor and a transceiver operatively coupled to the processor. The transceiver is configured to transmit an RRC reconfiguration message including configuration for at least one LTM candidate cell, and to transmit an LTM handover command media access control (MAC) CE instructing an LTM cell handover to be performed to an LTM candidate cell having the configuration included in the RRC reconfiguration message.

[0015] In another embodiment, a method for operating a UE is provided. The method includes: receiving an RRC reconfiguration message including configuration for at least one lower-layer LTM candidate cell; and receiving an LTM handover command MAC CE instructing an LTM cell handover from at least one LTM candidate cell to another LTM candidate cell. The method further includes sending an RA preamble to the LTM candidate cell indicated by the MAC CE for a repetition N times, and after the RA preamble has been sent N times, listening to the Physical Downlink Control Channel (PDCCH) in response to a random access response.

[0016] According to embodiments of this disclosure, a method performed by a user equipment (UE) is provided. The method includes: identifying that a random access procedure has not been completed; identifying whether a preamble transmission counter equals a specific value when the random access procedure repeatedly transmits a random access preamble and no contention-free random access resource is provided; and selecting a set of random access resources for the random access procedure when the preamble transmission counter equals the specific value and a set of random access resources associated with the number of repetitions of higher message 1 is available.

[0017] According to embodiments of this disclosure, a user equipment (UE) is provided. The UE includes a transceiver; and a controller coupled to the transceiver and configured to: identify that a random access procedure has not been completed; identify whether a preamble transmission counter is equal to a specific value when the random access procedure repeatedly transmits a random access preamble and no contention-free random access resource is provided; and select a set of random access resources for the random access procedure when the preamble transmission counter is equal to the specific value and a set of random access resources associated with the number of repetitions of higher message 1 is available.

[0018] Advantages of the invention

[0019] According to various embodiments of this disclosure, lower-layer triggered mobility processes can be effectively enhanced. Furthermore, according to various embodiments of this disclosure, the repetition of msg1 can be effectively performed. Additionally, according to various embodiments of this disclosure, handover using less Random Access Channel (RACH) resources with CG (Configured Grant) resources can be performed. Attached Figure Description

[0020] To gain a more complete understanding of this disclosure and its advantages, reference is now made to the following description in conjunction with the accompanying drawings, wherein:

[0021] Figure 1 An example wireless network according to an embodiment of the present disclosure is shown;

[0022] Figure 2A and Figure 2B An example wireless transmission and reception path according to an embodiment of this disclosure is shown;

[0023] Figure 3A An example UE according to an embodiment of the present disclosure is shown;

[0024] Figure 3B An example gNB according to an embodiment of this disclosure is shown;

[0025] Figure 4 An example process for lower-layer triggered mobility is illustrated according to an embodiment of this disclosure;

[0026] Figure 5An example process for lower-layer triggered mobility is illustrated according to an embodiment of this disclosure;

[0027] Figure 6 Another example process for lower-layer triggered mobility is shown according to an embodiment of this disclosure;

[0028] Figure 7 Another example process for lower-layer triggered mobility is shown according to an embodiment of this disclosure;

[0029] Figure 8 Another example process for lower-layer triggered mobility according to embodiments of this disclosure is shown; and

[0030] Figure 9 An example method for lower-layer triggered mobility is shown according to an embodiment of this disclosure;

[0031] Figure 10 A block diagram illustrating the structure of a terminal according to an embodiment of the present disclosure is shown; and

[0032] Figure 11 A block diagram illustrating the structure of a base station according to an embodiment of the present disclosure is shown. Detailed Implementation

[0033] The embodiments described herein, along with their various features and advantageous details, will be explained more fully with reference to the non-limiting embodiments illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques have been omitted to avoid unnecessarily obscuring the embodiments herein. The examples used herein are intended only to help understand how the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Therefore, these embodiments should not be construed as limiting the scope of the embodiments herein.

[0034] For the purposes of interpreting this specification, definitions (as defined herein) will apply, and terms used in the singular will also include the plural forms whenever appropriate, and vice versa. It should be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The terms “comprising,” “having,” and “including” should be interpreted as open-ended terms unless otherwise stated.

[0035] The words / phrases “exemplary,” “example,” “illustration,” “in an instance,” “and the like,” “and so on,” “etc.,” “etcetera,” “e.g.,” and “i.e.,” used herein, are used only to mean “serving as an example, illustration, or diagram.” Any embodiment or implementation of the subject matter of the invention described herein using the words / phrases “exemplary,” “example,” “illustration,” “in an instance,” “and the like,” “and so on,” “etc.,” “etcetera,” “e.g.,” and “i.e.,” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0036] The embodiments described herein can be illustrated as blocks that perform one or more of the described functions. These blocks may be referred to herein as managers, units, modules, hardware components, etc., and are physically implemented by analog and / or digital circuitry (e.g., logic gates, integrated circuits, microprocessors, microcontrollers, memory circuitry, passive electronic components, active electronic components, optical components, hardwired circuitry, etc.) and optionally driven by firmware. For example, the circuitry may be specifically implemented in one or more semiconductor chips or on a substrate support such as a printed circuit board. The circuitry constituting a block may be implemented by dedicated hardware, or by a processor (e.g., one or more programmed microprocessors and associated circuitry), or by a combination of dedicated hardware performing some functions of the block and a processor performing other functions of the block. Each block of an embodiment may be physically separated into two or more interactive and discrete blocks without departing from the scope of this disclosure. Similarly, the blocks of an embodiment may be physically combined into more complex blocks without departing from the scope of this disclosure.

[0037] It should be noted that the elements in the accompanying drawings are shown for descriptive and ease-of-understanding purposes and are not necessarily drawn to scale. For example, flowcharts / sequence diagrams illustrate methods of steps required to understand aspects of the embodiments disclosed herein. Furthermore, regarding the construction of the device, one or more components of the device may have been represented by conventional symbols in the drawings, and the drawings may only show those specific details relevant to understanding this embodiment so as not to obscure the drawings due to details that would be readily understood by those skilled in the art who would benefit from the description herein. Similarly, regarding the system, one or more components / modules constituting the system may have been represented by conventional symbols in the drawings, and the drawings may only show those specific details relevant to understanding this embodiment so as not to obscure the drawings due to details that would be readily understood by those skilled in the art who would benefit from the description herein.

[0038] The accompanying drawings are provided to aid in the easy understanding of the various technical features, and it should be understood that the embodiments presented herein are not limited to the drawings. Therefore, this disclosure should be construed as extending to any modifications, equivalents, and substitutions other than those specifically set forth in the drawings and corresponding descriptions. The use of terms such as first, second, third, etc., to describe components / elements / steps is for the purposes of this description and should not be construed as a sequential order / placement / occurrence unless otherwise stated.

[0039] The various embodiments discussed below, used to describe the principles of the disclosure in this patent document, are for illustrative purposes only and should not be construed as limiting the scope of this disclosure in any way. Those skilled in the art will understand that the principles of this invention can be implemented in any suitably arranged wireless communication system. For example, while the following detailed description of embodiments of this disclosure is directed to LTE and / or 5G communication systems, those skilled in the art will understand that the key points of this disclosure can also be applied, with slight modifications, to other communication systems with similar technical backgrounds and channel formats without departing from the scope of this disclosure. The technical solutions of the embodiments of this application can be applied to various communication systems, and for example, communication systems may include Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA) systems, Wideband Code Division Multiple Access (WCDMA) systems, General Packet Radio Service (GPRS) systems, Long Term Evolution (LTE) systems, LTE Frequency Division Duplex (FDD) systems, LTE Time Division Duplex (TDD) systems, Universal Mobile Telecommunications System (UMTS), Global Microwave Access Interoperability (WiMAX) communication systems, fifth-generation (5G) systems, or new radio (NR) systems, etc. Furthermore, the technical solutions of the embodiments of this application can be applied to future communication technologies.

[0040] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the same reference numerals in different drawings will be used to denote the same elements already described.

[0041] The demand for wireless data services is growing rapidly due to the increasing popularity of smartphones and other mobile data devices (such as tablets, notebook computers, netbooks, e-book readers, and machine-type devices) among consumers and businesses. To meet this high growth in mobile data services and support new applications and deployments, improvements in radio interface efficiency and coverage are paramount.

[0042] To meet the increased demand for wireless data traffic since the deployment of 4G communication systems, and to enable various vertical applications, 5G communication systems have been developed and are currently being deployed. Enabling technologies for 5G / NR mobile communication include: massive MIMO technology, moving from traditional cellular bands to higher frequency bands to provide beamforming gain and support greater capacity; new waveforms (such as new Radio Access Technologies (RATs)) to flexibly adapt to various services / applications with different needs; new multiple access schemes to support massive connectivity, and so on.

[0043] Other technical features will be readily apparent to those skilled in the art through the following drawings, description and claims.

[0044] Before proceeding with the detailed description below, it may be advantageous to define certain words and phrases used in this patent document. The term “coupled” and its derivatives refer to any direct or indirect communication between two or more elements, regardless of whether those elements are physically in contact with each other. The terms “transmit,” “receive,” and “communicate,” and their derivatives, include both direct and indirect communication. The terms “include” and “comprise,” and their derivatives, mean inclusion rather than limitation. The term “or” is inclusive, meaning and / or. The phrase “associated with” and its derivatives mean including, being included in, interconnected with, containing, being contained within, connected to or connected with, coupled to or coupled with, able to communicate with, cooperate with, interleaved, juxtaposed, proximate, bound to or bound with, having, possessing the properties of, having a relationship with, etc. The term “controller” refers to any device, system, or part thereof that controls at least one operation. Such a controller may be implemented in hardware or a combination of hardware and software and / or firmware. The functionality associated with any particular controller can be centralized or distributed, local or remote. When used with a list of items, the phrase "at least one of..." means that different combinations of one or more of the listed items can be used, and it may be necessary to use only one item from the list. For example, "at least one of A, B, and C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A, B, and C.

[0045] Furthermore, the various functions described below can be implemented or supported by one or more computer programs, each computer program being formed of computer-readable program code and specifically implemented in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, procedures, functions, objects, classes, instances, associated data, or portions thereof suitable for implementation in appropriate computer-readable program code. The phrase "computer-readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer-readable medium" includes any type of medium accessible by a computer, such as read-only memory (ROM), random access memory (RAM), hard disk drive, optical disc (CD), digital video disc (DVD), or any other type of storage. "Non-transitory" computer-readable media does not include wired, wireless, optical, or other communication links that transmit transient electrical or other signals. Non-transitory computer-readable media includes media in which data can be permanently stored and media in which data can be stored and later rewritten, such as rewritable optical discs or erasable storage devices.

[0046] Definitions of other specific words and phrases are provided throughout this patent document. Those skilled in the art will understand that, in many (if not most) cases, such definitions apply to the prior and future use of the words and phrases defined therein.

[0047] The following discussion Figures 1 to 11 The various embodiments described in this patent document are for illustrative purposes only and should not be construed as limiting the scope of this disclosure in any way. Those skilled in the art will understand that the principles of this invention can be implemented in any suitably arranged wireless communication system.

[0048] To meet the increased demand for wireless data traffic since the deployment of 4G communication systems and to enable various vertical applications, 5G / NR communication systems have been developed and are currently being deployed. 5G / NR communication systems are considered to be implemented in higher frequency (mmWave) bands (e.g., 28 GHz or 60 GHz) to achieve higher data rates, or in lower frequency bands (e.g., 6 GHz) to achieve robust coverage and mobility support. To reduce radio wave propagation loss and increase transmission distance, beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive MIMO technologies are discussed in 5G / NR communication systems.

[0049] In addition, in 5G / NR communication systems, system network improvements are being developed based on advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, coordinated multipoint (CoMP), and receiver interference cancellation.

[0050] The discussion of 5G systems and associated frequency bands is for reference only, as certain embodiments of this disclosure can be implemented in 5G systems. However, this disclosure is not limited to 5G systems or associated frequency bands, and embodiments of this disclosure can be used in conjunction with any frequency band. For example, aspects of this disclosure can also be applied to 5G communication systems, 6G, or even subsequent versions using terahertz (THz) frequency bands.

[0051] The following Figures 1-3B Various embodiments of communication technologies implemented in wireless communication systems and using orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) are described. Figures 1-3B The description does not imply any physical or architectural limitation on the ways in which different embodiments may be implemented. Different embodiments of this disclosure can be implemented in any suitably arranged communication system.

[0052] Figure 1 An example wireless network 100 according to an embodiment of this disclosure is shown. Figure 1 The embodiments of the wireless network shown are merely illustrative. Other embodiments of the wireless network 100 may be used without departing from the scope of this disclosure.

[0053] like Figure 1 As shown, the wireless network includes gNB 101 (e.g., a base station, BS), gNB 102, and gNB 103. gNB 101 communicates with gNB 102 and gNB 103. gNB 101 also communicates with at least one network 130, such as the Internet, a proprietary Internet Protocol (IP) network, or other data network.

[0054] gNB 102 provides wireless broadband access to network 130 to a first plurality of user equipments (UEs) within its coverage area 120. The first plurality of UEs includes: UE 111, which may be located in a small business; UE 112, which may be located in an enterprise; UE 113, which may be a WiFi hotspot; UE 114, which may be located in a first residence; UE 115, which may be located in a second residence; and UE 116, which may be a mobile device, such as a cellular phone, wireless laptop computer, wireless PDA, etc. gNB 103 provides wireless broadband access to network 130 to a second plurality of UEs within its coverage area 125. The second plurality of UEs includes UE 115 and UE 116. In some embodiments, one or more of gNBs 101-103 may communicate with each other and with UEs 111-116 using 5G / NR, Long Term Evolution (LTE), Advanced Long Term Evolution (LTE-A), WiMAX, WiFi, or other wireless communication technologies.

[0055] In another example, UE 116 may be within network coverage, while another UE may be outside network coverage (e.g., UE 111A-111C). In yet another example, both UEs are outside network coverage. In some embodiments, one or more of gNBs 101-103 may communicate with each other and with UEs 111-116 using 5G / NR, LTE, LTE-A, WiMAX, WiFi, or other wireless communication technologies. In some embodiments, UEs 111-116 may communicate using a device-to-device (D2D) interface known as PC5 (e.g., also referred to as a sidelink at the physical layer).

[0056] Depending on the network type, the term "base station" or "BS" can refer to any component (or set of components) configured to provide wireless access to a network, such as a transmitting point (TP), a transmitting-receiving point (TRP), an enhanced base station (eNodeB or eNB), a 5G / NR base station (gNB), a macro cell, a femtocell, a WiFi access point (AP), or other wireless enabling devices. A base station can provide wireless access according to one or more wireless communication protocols, such as 5G / NR 3rd Generation Partnership Project (3GPP) NR, Long Term Evolution (LTE), LTE-Advanced (LTE-A), High Speed ​​Packet Access (HSPA), Wi-Fi 802.11a / b / g / n / ac, etc. For convenience, the terms "BS" and "TRP" are used interchangeably in this patent document to refer to network infrastructure components that provide wireless access to remote terminals. Furthermore, depending on the network type, the term "user equipment" or "UE" can refer to any component such as a "mobile station," "subscriber station," "remote terminal," "wireless terminal," "receiving point," or "user equipment." For convenience, the terms “user equipment” and “UE” are used in this patent document to refer to a remote wireless device that wirelessly accesses the BS, regardless of whether the UE is a mobile device (such as a mobile phone or smartphone) or is generally considered to be a fixed device (such as a desktop computer or vending machine).

[0057] The dashed lines indicate the approximate extent of coverage areas 120 and 125, which are shown as approximately circular for illustrative and explanatory purposes only. It should be clearly understood that coverage areas associated with the gNB (such as coverage areas 120 and 125) may have other shapes, including irregular shapes, depending on the configuration of the gNB and variations in the radio environment associated with natural and man-made obstacles.

[0058] As described in more detail below, one or more of UEs 111-116 include circuitry, programming, or a combination thereof for lower-layer mobility in a wireless communication system. In some embodiments, one or more of gNBs 101-103 include circuitry, programming, or a combination thereof to support lower-layer mobility in a wireless communication system.

[0059] Although Figure 1 An example of a wireless network is shown, but more can be found on... Figure 1Various modifications can be made. For example, the wireless network can include any number of gNBs and any number of UEs in any suitable arrangement. Furthermore, gNB 101 can communicate directly with any number of UEs and provide these UEs with wireless broadband access to network 130. Similarly, each gNB 102-103 can communicate directly with network 130 and provide UEs with direct wireless broadband access to network 130. Additionally, gNBs 101, 102, and / or 103 can provide access to other or additional external networks, such as external telephone networks or other types of data networks.

[0060] As discussed in more detail below, wireless network 100 may have communication facilitated via one or more devices (e.g., UEs 111A to 111C), and one or more devices (e.g., UEs 111A to 111C) may have SL communication with UE 111. UE 111 can communicate directly with UEs 111A to 111C via a set of SLs (e.g., SL interfaces), providing sideline communication, for example, where UEs 111A to 111C are located in remote locations or require the convenience of network access connections beyond traditional forward and / or backhaul connections / interfaces or other than traditional forward and / or backhaul connections / interfaces (e.g., BS 102). In one example, whether BS 102 is supported or not, UE 111 can communicate directly with UEs 111A to 111C via SL communication. Each UE (e.g., as shown in UEs 112 to 116) is able to communicate with one or more of its other UEs (e.g., UEs 111A to 111C for UE 111).

[0061] Figure 2A and Figure 2B Example wireless transmit and receive paths according to embodiments of the present disclosure are illustrated. In the following description, transmit path 200 may be described as being implemented in a gNB (e.g., gNB 102), and receive path 250 may be described as being implemented in a UE (e.g., UE 116). However, it should be understood that receive path 250 may be implemented in a gNB, and transmit path 200 may be implemented in a UE. In some embodiments, transmit path 200 and / or receive path 250 are configured to implement and / or support lower-layer mobility in a wireless communication system as described in embodiments of the present disclosure.

[0062] The transmit path 200 includes a channel coding and modulation block 205, a serial-to-parallel (S-to-P) block 210, an N-size inverse fast Fourier transform (IFFT) block 215, a parallel-to-serial (P-to-S) block 220, a cyclic prefix addition block 225, and an up-converter (UC) 230. The receive path 250 includes a down-converter (DC) 255, a cyclic prefix removal block 260, a serial-to-parallel (S-to-P) block 265, an N-size fast Fourier transform (FFT) block 270, a parallel-to-serial (P-to-S) block 275, and a channel decoding and demodulation block 280.

[0063] In transmit path 200, channel coding and modulation block 205 receives a set of information bits, applies coding (such as low-density parity-check (LDPC) coding), and modulates the input bits (such as with quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM)) to generate a frequency-domain modulated symbol sequence. Serial-to-parallel block 210 converts (e.g., demultiplexes) the serial modulated symbols into parallel data to generate N parallel symbol streams, where N is the IFFT / FFT size used in gNB 102 and UE 116. IFFT block 215 of size N performs an IFFT operation on the N parallel symbol streams to generate a time-domain output signal. Parallel-to-serial block 220 converts (e.g., multiplexes) the parallel time-domain output symbols from IFFT block 215 of size N to generate a serial time-domain signal. Cyclic prefix addition block 225 inserts a cyclic prefix into the time-domain signal. Upconverter 230 modulates (e.g., upconverts) the output of the added cyclic prefix block 225 to the RF frequency for transmission via a wireless channel. The signal can also be filtered at the baseband before conversion to the RF frequency.

[0064] The RF signal transmitted from gNB 102 reaches UE 116 after passing through the wireless channel, and performs the opposite operation to that at gNB 102. Downconverter 255 downconverts the received signal to the baseband frequency, and cyclic prefix removal block 260 removes the cyclic prefix to generate a serial time-domain baseband signal. Serial-to-parallel block 265 converts the time-domain baseband signal into a parallel time-domain signal. An N-sized FFT block 270 performs an FFT algorithm to generate N parallel frequency-domain signals. Parallel-to-serial block 275 converts the parallel frequency-domain signals into a modulated data symbol sequence. Channel decoding and demodulation block 280 demodulates and decodes the modulated symbols to recover the original input data stream.

[0065] Each of gNBs 101-103 can implement a transmission path 200 similar to that used for transmitting to UEs 111-116 in the downlink, and a reception path 250 similar to that used for receiving from UEs 111-116 in the uplink. Similarly, each of UEs 111-116 can implement a transmission path 200 for transmitting to gNBs 101-103 in the uplink, and a reception path 250 for receiving from gNBs 101-103 in the downlink.

[0066] It can be implemented using only hardware or a combination of hardware and software / firmware. Figure 2A and 2B Each component in [the document]. As a specific example, Figure 2A and 2B At least some of the components can be implemented in software, while others can be implemented in configurable hardware or a combination of software and configurable hardware. For example, FFT block 270 and IFFT block 215 can be implemented as configurable software algorithms, where the value of size N can be modified according to the implementation.

[0067] Furthermore, although described as using FFT and IFFT, this is for illustrative purposes only and should not be construed as limiting the scope of this disclosure. Other types of transforms may be used, such as the Discrete Fourier Transform (DFT) and Inverse Discrete Fourier Transform (IDFT) functions. It should be understood that for DFT and IDFT functions, the value of variable N can be any integer (e.g., 1, 2, 3, 4, etc.), while for FFT and IFFT functions, the value of variable N can be any integer that is a power of 2 (e.g., 1, 2, 4, 8, 16, etc.).

[0068] although Figure 2A and 2B An example of a wireless transmit and receive path is shown, but it is possible to modify it further. Figure 2A and 2B Make various changes. For example, Figure 2A and 2B The various components can be combined, further subdivided, or omitted, and additional components can be added as needed. Furthermore, Figure 2A and 2B This is intended to illustrate examples of the types of transmit and receive paths that can be used in a wireless network. Any other suitable architecture can be used to support wireless communication in a wireless network.

[0069] Figure 3A An example UE 116 according to an embodiment of the present disclosure is shown. Figure 3A The embodiment of UE 116 shown is for illustrative purposes only, and Figure 1UEs 111-115 can have the same or similar configurations. However, UEs have a wide variety of configurations, and Figure 3A This disclosure is not intended to limit the scope of any particular implementation of the UE.

[0070] like Figure 3A As shown, UE 116 includes antenna(s) 305, transceivers(s) 310, and microphone(s) 320. UE 116 also includes speaker(s) 330, processor(s) 340, input / output (I / O) interface(IF) 345, input(s) 350, display(s) 355, and memory(s) 360. Memory(s) 360 includes operating system(OS) 361 and one or more applications(s) 362.

[0071] Multiple transceivers 310 receive input RF signals transmitted by gNBs of network 100 from multiple antennas 305. The multiple transceivers 310 down-convert the input RF signals to generate intermediate frequency (IF) or baseband signals. The IF or baseband signals are processed by RX processing circuitry in the multiple transceivers 310 and / or processor 340, which generates processed baseband signals by filtering, decoding, and / or digitizing the baseband or IF signals. The RX processing circuitry sends the processed baseband signals to a speaker 330 (e.g., for voice data) or to the processor 340 (e.g., for web browsing data).

[0072] The TX processing circuitry in (multiple) transceivers 310 and / or processor 340 receives analog or digital voice data from microphone 320 or other output baseband data (e.g., network data, email, or interactive video game data) from processor 340. The TX processing circuitry encodes, multiplexes, and / or digitizes the output baseband data to generate a processed baseband or IF signal. (Multiple) transceivers 310 up-convert the baseband or IF signal into an RF signal transmitted via (multiple) antennas 305.

[0073] Processor 340 may include one or more processors or other processing devices and executes OS 361 stored in memory 360 to control the overall operation of UE 116. For example, processor 340 may control transceiver(s)(s)310 to receive DL channel signals and transmit UL channel signals according to known principles. In some embodiments, processor 340 includes at least one microprocessor or microcontroller.

[0074] Processor 340 is also capable of executing other processes and programs residing in memory 360, such as processes for lower-level mobility in a wireless communication system, as discussed in more detail below. Processor 340 can move data into or out of memory 360 as needed for the execution of the process. In some embodiments, processor 340 is configured to execute application 362 based on OS 361 or in response to signals received from a gNB or operator. Processor 340 is also coupled to I / O interface 345, which provides UE 116 with the ability to connect to other devices such as laptop computers and handheld computers. I / O interface 345 is the communication path between these accessories and processor 340.

[0075] The processor 340 is also coupled to an input terminal 350 and a display 355, the input terminal 350 including, for example, a touchscreen, a keypad, etc. The operator of the UE 116 can use the input terminal 350 to input data into the UE 116. The display 355 may be a liquid crystal display, a light-emitting diode display, or other display capable of rendering text and / or at least limited graphics from a website.

[0076] The memory 360 is coupled to the processor 340. A portion of the memory 360 may include random access memory (RAM), while another portion of the memory 360 may include flash memory or other read-only memory (ROM).

[0077] Although Figure 3A An example of UE 116 is shown, but it is possible to modify it. Figure 3A Make various changes. For example, Figure 3A The various components can be combined, further subdivided, or omitted, and additional components can be added as needed. As a specific example, processor 340 can be divided into multiple processors, such as one or more central processing units (CPUs) and one or more graphics processing units (GPUs). In another example, transceiver 310 can include any number of transceivers and signal processing chains and can be connected to any number of antennas. Furthermore, although... Figure 3A The UE116 is shown configured as a mobile phone or smartphone, but the UE can also be configured to operate as other types of mobile or fixed devices.

[0078] Figure 3B An example gNB 102 according to an embodiment of the present disclosure is shown. Figure 3B The embodiment of gNB 102 shown is for illustrative purposes only, and Figure 1 gNBs 101 and 103 can have the same or similar configurations. However, gNBs have a wide variety of configurations, and Figure 3B This disclosure is not intended to limit the scope of any particular implementation of gNB.

[0079] like Figure 3B As shown, the gNB 102 includes multiple antennas 370a-370n, multiple transceivers 372a-372n, a controller / processor 378, a memory 380, and a backhaul or network interface 382.

[0080] Transceivers 372a-372n receive input RF signals from antennas 370a-370n, such as signals transmitted by a UE in network 100. Transceivers 372a-372n down-convert the input RF signals to generate IF or baseband signals. The IF or baseband signals are processed by receive (RX) processing circuitry in transceivers 372a-372n and / or controller / processor 378, which generates processed baseband signals by filtering, decoding, and / or digitizing the baseband or IF signals. Controller / processor 378 can further process the baseband signals.

[0081] The transmit (TX) processing circuitry in transceivers 372a-372n and / or controller / processor 378 receives analog or digital data (e.g., voice data, web data, email, or interactive video game data) from controller / processor 378. The TX processing circuitry encodes, multiplexes, and / or digitizes the output baseband data to generate a processed baseband or IF signal. Transceivers 372a-372n up-convert the baseband or IF signal into an RF signal transmitted via antennas 370a-370n.

[0082] The controller / processor 378 may include one or more processors or other processing devices for controlling the overall operation of the gNB 102. For example, the controller / processor 378 may control the transceivers 372a-372n to receive uplink (UL) channel signals and transmit downlink (DL) channel signals according to known principles. The controller / processor 378 may also support additional functions, such as more advanced wireless communication capabilities. For example, the controller / processor 378 may support beamforming or directional routing operations, where the output / input signals from / to multiple antennas 370a-370n are weighted differently to effectively manipulate the output signal in a desired direction. In the gNB 102, the controller / processor 378 may support any of a variety of other functions.

[0083] The controller / processor 378 is also capable of executing programs and other processes residing in the memory 380, such as an operating system, and processes that support lower-level mobility in wireless communication systems, as discussed in more detail below. The controller / processor 378 can move data into or out of the memory 380 as needed for the execution process.

[0084] The controller / processor 378 is also coupled to a backhaul or network interface 382. The backhaul or network interface 382 allows the gNB 102 to communicate with other devices or systems via a backhaul connection or over a network. Interface 382 can support communication via any suitable wired or wireless connection(s). For example, when the gNB 102 is implemented as part of a cellular communication system (such as a system supporting 5G / NR, LTE, or LTE-A), interface 382 can allow the gNB 102 to communicate with other gNBs via a wired or wireless backhaul connection. When the gNB 102 is implemented as an access point, interface 382 can allow the gNB 102 to communicate with a larger network (such as the Internet) via a wired or wireless local area network or via a wired or wireless connection. Interface 382 includes any suitable architecture supporting communication via wired or wireless connections (such as Ethernet or transceivers).

[0085] Memory 380 is coupled to controller / processor 378. A portion of memory 380 may include RAM, while another portion of memory 380 may include flash memory or other ROM.

[0086] Although Figure 3B An example of gNB 102 is shown, but it is possible to compare it with other models. Figure 3B Various changes can be made. For example, gNB102 can include... Figure 3B Each component, in any number as shown. Furthermore, Figure 3B The various components can be combined, further subdivided or omitted, and additional components can be added as needed.

[0087] In next-generation wireless communication systems operating in the high-frequency (mmWave) band (e.g., 5G, ultra-5G, 6G), UEs and gNBs use beamforming to communicate with each other. Beamforming techniques are used to mitigate propagation path loss and increase propagation distance in higher frequency bands. Beamforming uses high-gain antennas to enhance transmit and receive performance. Beamforming can be classified into transmit (TX) beamforming performed at the transmitting end and receive (RX) beamforming performed at the receiving end. Typically, TX beamforming increases directivity by using multiple antennas to allow the area reached by propagation to be densely located in a specific direction. In this case, the aggregation of multiple antennas can be called an antenna array, and each antenna included in the array can be called an array element. Antenna arrays can be configured in various forms, such as linear arrays, planar arrays, etc. The use of TX beamforming results in increased signal directivity, thereby increasing propagation distance. Furthermore, since the signal is transmitted almost entirely in directions other than the directional direction, signal interference acting on another receiver is significantly reduced. The receiver can perform beamforming on the RX signal by using an RX antenna array. RX beamforming increases the strength of the RX signal transmitted in a specific direction by allowing propagation to be concentrated in that direction, and excludes signals transmitted in directions other than the specified direction from the RX signal, thus providing a blocking effect against interfering signals. By using beamforming technology, a transmitter can generate multiple transmit beam patterns in different directions. Each of these transmit beam patterns can also be referred to as a transmit (TX) beam. Wireless communication systems operating at high frequencies use multiple narrow TX beams to transmit signals within a cell because each narrow TX beam provides coverage to a portion of the cell. The narrower the TX beam, the higher the antenna gain, and therefore the greater the propagation distance of the signal transmitted using beamforming. Receivers can also generate multiple receive (RX) beam patterns in different directions. Each of these receive patterns can also be referred to as a receive (RX) beam.

[0088] Next-generation wireless communication systems (e.g., 5G, 5G+, 6G) support standalone operation mode and dual connectivity (DC). In DC, multiple Rx / Tx UEs can be configured to utilize resources provided by two different nodes (or NBs) via a non-ideal backhaul connection. One node acts as the primary node (MN), and the other acts as the secondary node (SN). The MN and SN are connected via a network interface, and at least the MN is connected to the core network. NR also supports multi-RAT dual connectivity (MR-DC) operation, whereby a UE in the RRC_CONNECTED state is configured to utilize radio resources provided by two different schedulers located in two different nodes via a non-ideal backhaul connection, providing E-UTRA (i.e., if the node is an ng-eNB) or NR access (i.e., if the node is a gNB). In NR for UEs in the RRC_CONNECTED state without a configured CA / DC, only one serving cell includes the primary cell. For a UE configured with CA / DC in the RRC_CONNECTED state, the term "serving cell" is used to refer to a set of cells including (multiple) specific cells (SpCells) and all secondary cells (SCells). In NR, the term Primary Cell Group (MCG) refers to a group of serving cells associated with a primary node, which includes the primary cell (PCell) and one or more optional SCells. In NR, the term Secondary Cell Group (SCG) refers to a group of serving cells associated with a secondary node, which includes the PSCell and one or more optional SCells. In NR, a PCell refers to the serving cell in an MCG operating on the primary frequency, where the UE performs an initial connection establishment procedure or initiates a connection re-establishment procedure. In NR for UEs configured with CA, an SCell is a cell that provides additional radio resources over a specific cell. The primary SCG cell (PSCell) refers to the serving cell in an SCG, where the UE performs random access when performing a reconfiguration procedure with Sync. For dual connectivity operation, the term SpCell refers to either the PCell of the MCG or the PSCell of the SCG; otherwise, the term specific cell refers to the PCell.

[0089] In next-generation wireless communication systems (e.g., 5G, 5G+, 6G), the cell broadcast synchronization signal and the Node B (gNB) or base station in the PBCH block (SSB) include the primary synchronization signal and secondary synchronization signals (PSS, SSS) as well as system information. System information includes common parameters required for communication within the cell. In fifth-generation wireless communication systems (also known as next-generation radio or NR), system information (SI) is divided into a main information block (MIB) and multiple system information blocks (SIBs), where: the MIB is transmitted on the BCH at a period of 80ms and repeated within 80ms, and the MIB includes the parameters required to obtain SIB1 from the cell. SIB1 is transmitted on the DL-SCH at a period of 160ms with variable transmission repetition. The default transmission repetition period for SIB1 is 20ms, but the actual transmission repetition period depends on the network implementation. For SSB and Control Resource Set (CORESET) multiplexing mode 1, the SIB1 repetition transmission period is 20ms. For SSB and CORESET multiplexing modes 2 / 3, the SIB1 transmission repetition period is the same as the SSB period. SIB1 includes information about the availability and scheduling of other SIBs (e.g., SIB-to-SI message mapping, period, SI window size), indicating whether one or more SIBs are provided only on demand, and the configuration required for the UE to execute an SI request in this case. SIB1 is a cell-specific SIB; SIBs other than SIB1 and posSIB are carried in System Information (SI) messages, which are transmitted on the DL-SCH. SIBs or posSIBs with the same period can be mapped to the same SI message. SIBs and posSIBs can be mapped to different SI messages. Each SI message is transmitted within a periodically occurring time-domain window (referred to as an SI window of equal length for all SI messages). Each SI message is associated with an SI window, and the SI windows for different SI messages do not overlap. That is, only the corresponding SI message is transmitted within an SI window. SI messages can be transmitted multiple times within an SI window. Using the indications in SIB1, any SIB or posSIB other than SIB1 can be configured to be cell-specific or region-specific. Cell-specific SIBs can only be applied to the cell providing the SIB, while area-specific SIBs can be applied to an area called an SI area, which includes one or more cells and is identified by the systemInformationAreaID. The mapping from SIB to SI message is configured in the schedulingInfoList, while the mapping from posSIB to SI message is configured in the pos-SchedulingInfoList. Each SIB is included in a single SI message, and each SIB and posSIB is included in an SI message at most once.For UEs in the RRC_CONNECTED state, the network can provide system information via dedicated signaling using RRCReconfiguration messages, for example, if the UE has an active BWP in the common search space that is not configured to listen for system information, paging, or when requested by the UE. In the RRC_CONNECTED state, the UE obtains the required SIB(s) from the PCell. For PSCells and SCells, the network provides the required SIs via dedicated signaling (i.e., within the RRC Reconfiguration message). However, the UE will obtain the MIB of the PSCell to obtain the SFN timing of the SCG (which may differ from the MCG). When the associated SI of the SCell changes, the network releases and adds the associated SCell. For PSCells, the required SIs can be changed using a reconfiguration with synchronization.

[0090] In next-generation wireless communication systems (e.g., 5G, 5G+, 6G), the Physical Downlink Control Channel (PDCCH) is used to schedule DL transmissions on the Physical Downlink Shared Channel (PDSCH) and UL transmissions on the Physical Uplink Shared Channel (PUSCH). The downlink control information (DCI) on the PDCCH includes: downlink assignment, which at least contains modulation and coding formats, resource allocation, and hybrid ARQ information related to the DL-SCH; and uplink scheduling authorization, which at least contains modulation and coding formats, resource allocation, and hybrid ARQ information related to the UL-SCH. Besides scheduling, PDCCH can be used for: activating and deactivating configured PUSCH transmissions using configured authorizations; activating and deactivating PDSCH semi-persistent transmissions; informing one or more UEs of slot formats; notifying one or more UEs of PRBs and OFDM symbols, where the UE may assume no transmission is directed to the UE; sending TPC commands for PUCCH and PUSCH; sending one or more TPC commands for SRS transmissions by one or more UEs; switching the active bandwidth portion of a UE; and initiating a random access procedure. The UE listens for a set of PDCCH candidates in one or more configured control resource sets (CORESETs) at configured listening times according to the corresponding search space configuration. A CORESET includes a set of PRBs with durations of 1 to 3 OFDM symbols. Resource element groups (REGs) and control channel elements (CCEs) are defined within a CORESET, where each CCE includes a set of REGs. Control channels are formed by aggregating CCEs. Different coding rates for control channels are achieved by aggregating different numbers of CCEs. Interleaved and non-interleaved CCE-to-REG mappings are supported in a CORESET. Polar coding is used in the PDCCH. Each resource element group carrying the PDCCH carries its own DMRS. QPSK modulation is used in the PDCCH.

[0091] In next-generation wireless communication systems (e.g., 5G, 5G+, 6G), the GNB signals a list of search space configurations for each configured BWP of the serving cell, where each search configuration is uniquely identified by a search space identifier. Within the serving cell's BWP, the search space identifier is unique. For each configured BWP, the gNB explicitly signals the identifier of the search space configuration to be used for specific purposes such as paging reception, SI reception, and random access response reception. In NR, the search space configuration includes the parameters Monitoring-periodicity-PDCCH-slot, Monitoring-offset-PDCCH-slot, Monitoring-symbols-PDCCH-within-slot, and duration. The UE uses the parameters Monitoring-periodicity-PDCCH-slot, Monitoring-offset-PDCCH-slot, and Monitoring-symbols-PDCCH-within-slot to determine the timing of multiple PDCCH monitoring sessions within a slot. The PDCCH monitoring timing occurs during the duration from slot "x" to x+, where the slot with number "x" in a radio frame with number "y" satisfies the following Equation 1:

[0092] [Equation 1]

[0093] (y * (number of time slots in a radio frame) + x - Monitoring-offset-PDCCH-slot) mod (Monitoring-periodicity-PDCCH-slot) = 0.

[0094] The start symbol of the PDCCH listening opportunity in each slot with a PDCCH listening opportunity is given by Monitoring-symbols-PDCCH-within-slot. The length of the PDCCH listening opportunity (in symbols) is given in the CORESET associated with the search space. The search space configuration includes an identifier for the CORESET configuration associated with it. For each configuration's BWP of the serving cell, the gNB signals a list of CORESET configurations, where each CORESET configuration is uniquely identified by a CORESET identifier. The Coreset identifier is unique within the BWP of the serving cell. Note that each radio frame has a duration of 10 ms. Radio frames are identified by either a radio frame number or a system frame number. Each radio frame includes several slots, where the number of slots and the duration of the slots in a radio frame depend on the subcarrier spacing. The number of slots and the duration of the slots in a radio frame are predefined in the NR for each supported SCS. Each CORESET configuration is associated with a list of TCI (Transmission Configuration Indicator) states. Each TCI state configures a DL RS ID (SSB or CSI RS). The TCI status list corresponding to the CORESET configuration is signaled by the gNB via RRC signaling. One of the TCI statuses in the TCI status list is activated and indicated to the UE by the gNB. The TCI status indication is used by the gNB to transmit the DL TX beam of the PDCCH during PDCCH listening in the search space (the DL TX beam and the SSB / CSI RS of the TCI status are QCL).

[0095] In next-generation wireless communication systems (e.g., 5G, 5G+, 6G), bandwidth adaptation (BA) is supported. Using BA, the UE's receive and transmit bandwidth does not need to be as large as the cell's bandwidth and can be adjusted: the bandwidth can be commanded to change (e.g., shrinking during low-activity periods to save power); the location can be moved in the frequency domain (e.g., to increase scheduling flexibility); and the subcarrier spacing can be commanded to change (e.g., to allow different services). A subset of the cell's total cell bandwidth is called the Bandwidth Part (BWP). BA is implemented by configuring an RRC-connected UE with (multiple) BWPs and informing the UE which configured BWP is currently active. When BA is configured, the UE only needs to listen to the PDCCH on one active BWP; that is, it does not need to listen to the PDCCH on the entire DL frequency of the serving cell. In RRC-connected state, the UE is configured with one or more DL and UL BWPs for each configured serving cell (i.e., PCell or SCell). For an active serving cell, there is always one active UL and DL BWP at any given time. Serving cell BWP handover is used to activate an inactive BWP and deactivate the active BWP once. BWP handover is controlled by the PDCCH indicating downlink assignment or uplink grant, by the bwp-InactivityTimer, by RRC signaling, or by the MAC entity itself when initiating the random access procedure. When adding a subcell or activating a SCell, the DL BWP and UL BWP indicated by firstActiveDownlinkBWP-Id and firstActiveUplinkBWP-Id, respectively, are active and do not receive the PDCCH indicating downlink assignment or uplink grant. The active BWP of the serving cell is indicated by RRC or PDCCH. For unpaired spectrum, the DL BWP is paired with the UL BWP, and BWP handover is common to both UL and DL. When the BWP inactivity timer expires, the UE switches from the active DL BWP to the default DL BWP or the initial DL BWP (if the default DL BWP is not configured).

[0096] In next-generation wireless communication systems (e.g., 5G, 5G+, 6G), random access (RA) is supported. Random access (RA) is used to achieve uplink (UL) time synchronization. RA is used during initial access, handover, Radio Resource Control (RRC) connection re-establishment procedures, scheduling request transmission, secondary cell group (SCG) addition / modification, beam fault recovery, and data or control information transmission in the UL by asynchronous UEs in RRC-connected states. Several types of random access procedures are supported.

[0097] In contention-based random access (CBRA), also known as 4-step CBRA, the UE first sends a random access preamble (also known as Msg1) and then waits for a random access response (RAR) within the RAR window. The RAR is also known as Msg2. The next-generation node B (gNB) sends the RAR on the PDSCH. The PDCCH that schedules the PDSCH carrying the RAR is addressed to the RA radio network temporary identifier (RA-RNTI). The RA-RNTI identifies the time-frequency resource in which the gNB detects the RA preamble (also known as the physical RA channel (PRACH) timing, PRACH transmission (TX) timing, or RA channel [RACH] timing). The RA-RNTI is calculated as follows: RA-RNTI = 1 + s_id + 14*t_id + 14*80*f_id + 14*80*8*ul_carrier_id, where s_id is the index of the first Orthogonal Frequency Division Multiplexing (OFDM) symbol of the PRACH timing in which the UE has transmitted Msg1 (i.e., the RA preamble); 0 ≤ s_id < 14; t_id is the index of the first slot of the PRACH timing (0 ≤ t_id < 80); f_id is the index of the PRACH timing within the slot in the frequency domain (0 ≤ f_id < 8), and ul_carrier_id is the UL carrier used for transmission of Msg1 (0 for normal UL (NUL) carrier, 1 for supplementary UL (SUL) carrier). Several RARs detected by the gNB for various random access preambles can be multiplexed by the gNB in ​​the same RAR Media Access Control (MAC) Protocol Data Unit (PDU). If the RAR includes the RA preamble identifier (RAPID) of the RA preamble sent by the UE, then the RAR in the MAC PDU corresponds to the UE's RA preamble transmission. If no RAR corresponding to the UE's RA preamble transmission is received during the RAR window, and the UE has not yet completed the configurable number of RA preamble transmissions (configured by the gNB in ​​the RACH configuration), the UE returns to step one, i.e., selects a random access resource (preamble / RACH timing), and transmits the RA preamble. Backoff can be applied before returning to step one.

[0098] If the UE receives a RAR corresponding to its RA preamble, it sends message 3 (Msg3) in the UL grant received in the RAR. Msg3 includes messages such as RRC connection request, RRC connection re-establishment request, RRC handover confirmation, scheduling request, and SI request. Msg3 may include the UE identity (i.e., Cell Radio Network Temporary Identifier (C-RNTI) or System Architecture Evolution (SAE) - Temporary Mobile Subscriber Identity (S-TMSI) or a random number). After sending Msg3, the UE starts a contention resolution timer. While the contention resolution timer is running, if the UE receives a Physical Downlink Control Channel (PDCCH) addressed to the C-RNTI included in Msg3, contention resolution is considered successful, the contention resolution timer is stopped, and the RA procedure is completed. While the contention resolution timer is running, if the UE receives a Contention Resolution MAC Control Element (CE) including the UE's contention resolution identifier (the first X bits of the Common Control Channel [CCCH] Service Data Unit [SDU] sent in Msg3), contention resolution is considered successful, the contention resolution timer is stopped, and the RA procedure is completed. If the contention resolution timer expires and the UE has not sent the RA preamble a configurable number of times, the UE returns to step one, i.e., selects random access resources (preamble / RACH timing) and sends the RA preamble. Backoff can be applied before returning to step one.

[0099] Contention-Free Random Access (CFRA), also known as Traditional CFRA or 4-Step CFRA, is used in scenarios such as handover requiring low latency and early timing setup for secondary cells (Scells). The evolved Node B (eNB) assigns a dedicated random access preamble to the UE. The UE sends the dedicated RA preamble. The eNB sends a Redirect Access Receiver (RAR) on the PDSCH addressed to the RA-RNTI. The RAR transmits the RA preamble identifier and timing alignment information. The RAR may also include UL authorization. The RAR is sent within a RAR window similar to the Contention-Based RA (CBRA) procedure. CFRA is considered successfully completed after receiving the RAR including the RA preamble identifier (RAPID) sent by the UE. In the case where the RA is initiated for beam fault recovery, CFRA is considered successfully completed if a PDCCH addressed to the C-RNTI is received in the search space for beam fault recovery. If the RAR window expires and the RA is not successfully completed, and the UE has not sent the RA preamble a configurable number of times (configured by the gNB in ​​the RACH configuration), the UE will retransmit the RA preamble.

[0100] For certain events, such as handover and beam failure recovery, if a dedicated preamble is assigned to the UE during the first step of random access, i.e., during the random access resource selection for Msg1 transmission, the UE determines whether to transmit a dedicated preamble or a non-dedicated preamble. Typically, dedicated preambles are provided for a subset of SSB / CSI RSs. If, among the SSB / CSI RSs for which the gNB provides contention-free random access resources (i.e., dedicated preambles / ROs), there are no SSB / CSI RSs with a DL RSRP higher than a threshold, the UE selects a non-dedicated preamble. Otherwise, the UE selects a dedicated preamble. Therefore, during the RA procedure, one random access attempt can be a CFRA, while other random access attempts can be CBRAs.

[0101] For two-step contention-based random access (2-step CBRA), in the first step, the UE transmits a random access preamble on the PRACH and a payload (i.e., MAC PDU) on the PUSCH. The transmission of the random access preamble and payload is also referred to as MsgA. In the second step, after the transmission of MsgA, the UE listens for a response from the network (i.e., gNB) within a configured window. This response is also referred to as MsgB. The next-generation node B (gNB) transmits MsgB on the PDSCH. The PDCCH that schedules the PDSCH carrying MsgB is addressed to the MsgB radio network temporary identifier (MSGB-RNTI). The MSGB-RNTI identifies the time-frequency resource in which the RA preamble is detected by the gNB (also known as the physical RA channel [PRACH] timing, PRACH transmission [TX] timing, or RA channel [RACH] timing). MSGB-RNTI is calculated as follows: RA-RNTI = 1 + s_id + 14*t_id + 14*80*f_id + 14*80*8*ul_carrier_id + 14×80×8×2, where s_id is the index of the first orthogonal frequency division multiplexing (OFDM) symbol of the PRACH timing in which the UE has transmitted Msg1 (i.e., the RA preamble); 0≤s_id<14; t_id is the index of the first time slot of the PRACH timing (0≤t_id< 80); f_id is the index of the PRACH timing in the time slot in the frequency domain (0≤f_id< 8), and ul_carrier_id is the UL carrier used for transmission of Msg1 (0 for normal UL (NUL) carrier, 1 for supplementary UL (SUL) carrier).

[0102] If a Common Control Channel (CCCH) Service Data Unit (SDU) is transmitted in the MsgA payload, the UE uses the contention resolution information in MsgB to perform contention resolution. Contention resolution is successful if the contention resolution identifier received in MsgB matches the first 48 bits of the CCCH SDU transmitted in MsgA. If a C-RNTI is transmitted in the MsgA payload, contention resolution is successful if the UE receives a PDCCH addressed to the C-RNTI. If contention resolution is successful, the random access procedure is considered to have completed successfully. Instead of the contention resolution information corresponding to the transmitted MsgA, MsgB may include fallback information corresponding to the random access preamble transmitted in MsgA. If fallback information is received, the UE transmits Msg3 and uses Msg4 to perform contention resolution as in the CBRA procedure. If contention resolution is successful, the random access procedure is considered to have completed successfully. If contention resolution fails during fallback (i.e., when transmitting Msg3), the UE retransmits MsgA. If the window in which the UE is configured to listen for network responses expires after sending MsgA, and the UE has not yet received MsgB including contention resolution or fallback information as described above, the UE retransmits MsgA. If the random access procedure fails to complete successfully even after sending MsgA a configurable number of times, the UE returns to the 4-step RACH procedure, i.e., the UE only sends the PRACH preamble.

[0103] The MsgA payload may include one or more of the following: Common Control Channel (CCCH) Service Data Unit (SDU), Dedicated Control Channel (DCCH) SDU, Dedicated Traffic Channel (DTCH) SDU, Buffer Status Report (BSR) MAC Control Element (CE), Power Headroom Report (PHR) MAC CE, SSB information, C-RNTI MAC CE, or padding. In the first step, the MsgA may include the UE ID (e.g., Random ID, S-TMSI, C-RNTI, Recovery ID, etc.) and a preamble. The UE ID may be included in the MAC PDU of the MsgA. UE IDs such as C-RNTI may be carried in the MAC CE, where the MAC CE is included in the MAC PDU. Other UE IDs (such as Random ID, S-TMSI, C-RNTI, Recovery ID, etc.) may be carried in the CCCH SDU. The UE ID may be one of the following: Random ID, S-TMSI, C-RNTI, Recovery ID, IMSI, Idle Mode ID, Inactive Mode ID, etc. The UE ID may be different in different scenarios in which the UE performs the RA procedure. When the UE performs a Re-Action (RA) after power-on (before the UE is attached to the network), the UE ID is a random ID. When the UE performs an RA in idle state after being attached to the network, the UE ID is the S-TMSI. If the UE has an assigned C-RNTI (e.g., in connected state), the UE ID is the C-RNTI. When the UE is inactive, the UE ID is the recovery ID. In addition to the UE ID, some additional control (ctrl) information can be sent in the MsgA. Control information can be included in the MAC PDU of the MsgA. Control information may include one or more of the following: connection request indication, connection restoration request indication, SI request indication, buffer status indication, beam information (e.g., one or more DL TX beam IDs or SSBIDs), beam failure recovery indication / information, data indicator, cell / BS / TRP handover indication, connection re-establishment indication, reconfiguration complete or handover complete message, etc.

[0104] In two-step contention-free random access (2-step CFRA), the gNB assigns the UE multiple dedicated random access preambles and multiple PUSCH resources for MsgA transmission. Multiple ROs may also be specified for preamble transmission. In the first step, the UE transmits the random access preamble on the PRACH and the payload on the PUSCH using the contention-free random access resources (i.e., dedicated preamble / PUSCH resources / ROs). In the second step, after MsgA transmission, the UE listens for a response from the network (i.e., the gNB) within a configured window. This response is also referred to as MsgB.

[0105] The next-generation node B (gNB) transmits MsgB on the Physical Downlink Shared Channel (PDSCH). The PDCCH that schedules the PDSCH carrying MsgB is addressed to the MsgB Radio Network Temporary Identifier (MSGB-RNTI). The MSGB-RNTI identifies the time-frequency resource in which the RA preamble is detected by the gNB (also known as the Physical RA Channel [PRACH] timing, PRACH Transmission [TX] timing, or RA Channel [RACH] timing). MSGB-RNTI is calculated as follows: RA-RNTI = 1 + s_id + 14*t_id + 14*80*f_id + 14*80*8*ul_carrier_id + 14×80×8×2, where s_id is the index of the first orthogonal frequency division multiplexing (OFDM) symbol of the PRACH timing in which the UE has transmitted Msg1 (i.e., the RA preamble); 0≤s_id<14; t_id is the index of the first time slot of the PRACH timing (0≤t_id< 80); f_id is the index of the PRACH timing in the time slot in the frequency domain (0≤f_id< 8), and ul_carrier_id is the UL carrier used for transmission of Msg1 (0 for normal UL (NUL) carrier, 1 for supplementary UL (SUL) carrier).

[0106] If the UE receives a PDCCH addressed to C-RNTI, it considers the random access procedure to have been successfully completed. If the UE receives a backoff message corresponding to the preamble it sent, it considers the random access procedure to have been successfully completed.

[0107] For certain events, such as handover and beam failure recovery, if during the first step of random access (i.e., during random access resource selection for MsgA transmission), multiple dedicated preambles and multiple PUSCH resources are assigned to the UE, the UE determines whether to transmit a dedicated preamble or a non-dedicated preamble. Typically, a dedicated preamble is provided for a subset of the SSB / CSI RSs. If there are no SSB / CSI RSs with a DL RSRP higher than a threshold among those for which the gNB provides contention-free random access resources (i.e., dedicated preamble / RO / PUSCH resources), the UE selects a non-dedicated preamble. Otherwise, the UE selects a dedicated preamble. Therefore, during the RA procedure, one random access attempt can be a 2-step CFRA, while other random access attempts can be a 2-step CBRA.

[0108] When initiating a random access procedure, the UE first selects a carrier (SUL or NUL). If the carrier to be used for the random access procedure is explicitly signaled by the gNB, the UE selects the signaled carrier to perform the random access procedure. If the carrier to be used for the random access procedure is not explicitly signaled by the NB, and if the serving cell used for the random access procedure is configured with supplementary uplink, and if the downlink path loss reference RSRP is less than rsrp-ThresholdSSB-SUL, the UE selects the SUL carrier to perform the random access procedure. Otherwise, the UE selects the NUL carrier to perform the random access procedure. When selecting the UL carrier, the UE determines the UL and DL BWP to be used for the random access procedure. Then, the UE determines whether to perform a 2-step or 4-step RACH for the random access procedure.

[0109] If the random access procedure is initiated by a PDCCH command, and if the ra-PreambleIndex explicitly provided by the PDCCH is not 0b000000, the UE selects a 4-step RACH. Otherwise, if the gNB signals that 2-step contention-free random access resources are used for the random access procedure, the UE selects a 2-step RACH. Otherwise, if the gNB signals that 4-step contention-free random access resources are used for the random access procedure, the UE selects a 4-step RACH. Otherwise, if the UL BWP selected for the random access procedure is configured with only 2-step RACH resources, the UE selects a 2-step RACH. Otherwise, if the ULBWP selected for the random access procedure is configured with only 4-step RACH resources, the UE selects a 4-step RACH. Otherwise, if the UL BWP selected for the random access procedure is configured with both 2-step and 4-step RACH resources, and if the downlink path loss reference RSRP is lower than the configured threshold, the UE selects a 4-step RACH. Otherwise, the UE selects a 2-step RACH.

[0110] Layer 1 (L1) / Layer 2 (L2) triggered mobility (LTM), also referred to herein as lower-layer triggered mobility, is a process in which the gNB receives multiple L1 and / or L3 measurement reports from the UE, and based on these reports, the gNB changes the UE's serving cell via a cell handover command signaled via the MAC CE. The cell handover command indicates the gNB's previously prepared LTM candidate cell configuration and provides it to the UE via RRC signaling. The UE then hands over to the target cell according to the cell handover command. LTM procedures can be used to reduce mobility latency. The network can request the UE to perform early TA acquisition of the candidate cell before cell handover. Early TA acquisition is triggered by a PDCCH command or by UE-based TA measurements.

[0111] The network indicates in the cell handover command whether the UE will access the target cell using the RA procedure (if no TA value is provided) or using the indicated TA value to access the target cell via PUSCH. For RACH-less LTM, the UE accesses the target cell with the configured grant provided in the RRC signaling and selects the configured grant timing associated with the beam indicated in the cell handover command. If the UE does not receive the configured grant in the RRC signaling, the UE listens for the PDCCH for dynamic scheduling from the target cell during LTM cell handover. If the UE does not have valid PUCCH resources for the triggered SR before the RACH-less LTM procedure is completed, the UE will not trigger the random access procedure.

[0112] Figure 4 An example process 400 for lower-layer triggered mobility is shown according to an embodiment of this disclosure. Figure 4 The embodiments of the processes shown are for illustrative purposes only. Figure 4 One or more of the components shown can be implemented in a dedicated circuit configured to perform the function, or one or more of the components can be implemented by one or more processors that execute instructions to perform the function. Other embodiments of lower-layer triggered mobility may be used without departing from the scope of this disclosure.

[0113] exist Figure 4 In the example, UE 402 is in the RRC_CONNECTED state. In step 1, UE 402 sends a MeasurementReport message to gNB 404. GNB 404 decides to configure LTM and initiates candidate cell preparation (multiple).

[0114] Step 2: gNB 404 sends an RRC reconfiguration message to UE 402, which includes LTM candidate cell configurations for one or more candidate cells.

[0115] Step 3: UE 402 stores the LTM candidate cell configuration and sends an RRC reconfiguration complete message to gNB 404.

[0116] In step 4a, UE 402 may perform DL synchronization with (multiple) candidate cells before receiving a cell handover command.

[0117] In step 4b, if requested by the network, UE 402 performs early TA acquisition on (multiple) candidate cells before receiving the cell handover command. Early TA acquisition is performed via CFRA triggered by a PDCCH command from the source cell, after which UE 402 sends a preamble to the indicated candidate cell. To minimize data interruption to the source cell due to CFRA on (multiple) candidate cells, UE 402 does not receive RAR for TA value acquisition purposes and indicates the TA value of the candidate cell in the cell handover command. The UE does not maintain a TA timer for the candidate cells and relies on the network implementation to guarantee TA validity.

[0118] In step 5, UE 402 performs L1 measurements on the configured candidate cells and sends an L1 measurement report to gNB 404.

[0119] In step 6, gNB 404 determines to perform a cell handover to the target cell and sends a MAC CE to trigger the handover, including a candidate configuration index for the target cell. UE 402 switches to the target cell and applies the configuration indicated by the candidate configuration index.

[0120] In step 7, if UE 402 does not have a valid TA for the target cell, then UE 402 performs a random access procedure for the target cell.

[0121] Step 8: UE 402 completes the LTM cell handover process by sending an RRC reconfiguration complete message to the target cell. If UE 402 has performed a random access (RA) procedure in step 7, UE 402 is considered to have successfully completed LTM when the random access procedure is successfully completed. For RACH-free LTM, UE 402 is considered to have successfully completed LTM when it determines that the network has successfully received its first uplink (UL) data. UE 402 determines that its first UL data has been successfully received by receiving the PDCCH addressing UE 402's C-RNTI in the target cell. This PDCCH is used to schedule new transmissions after the first UL data.

[0122] Although Figure 4 An example procedure 400 for mobility triggered by a lower layer is shown, but it is possible to modify... Figure 4 Make various changes. For example, although it is displayed as a series of steps, Figure 4 The steps in the process can overlap, occur in parallel, occur in different orders, occur any number of times, be omitted, or be replaced by other steps.

[0123] In existing wireless communication systems, the network (e.g., gNB or candidate cell) does not know which SSB / CSI RS / beam will be good / suitable during cell handover. Therefore, the network provides a contention-free random access configuration (i.e., preamble / preamble index, PUSCH timing / PUSCH timing index) for each SSB / CSI RS / beam in the LTM configuration. Figure 4 Step 2) leads to a waste of limited contention-free random access resources. Furthermore, the network can keep its contention-free configuration updated based on the latest measurements. Updating the configuration may require interaction between the serving cell and candidate cells, and also incurs signaling overhead. To overcome these problems, this disclosure provides an LTM cell handover procedure characterized by reduced overhead. This disclosure also provides a procedure for Msg1 repetition during LTM cell handover, as Msg1 repetition can be beneficial for RA-based LTM cell handover for extended coverage. The procedure includes selecting the number of Msg1 repetitions, and criteria for backing down from a lower number of repetitions to a higher number of repetitions.

[0124] Figure 5 An example process 500 for lower-layer triggered mobility is shown according to an embodiment of this disclosure. Figure 5 The embodiments of the methods shown are for illustrative purposes only. Figure 5 One or more of the components shown can be implemented in a dedicated circuit configured to perform the function, or one or more of the components can be implemented by one or more processors that execute instructions to perform the function. Other embodiments for lower-level triggering mobility may be used without departing from the scope of this disclosure.

[0125] exist Figure 5In the example, the process begins at step 510. In step 510, the gNB (or base station) 504 of cell A provides the LTM configuration of candidate cell B to UE 502. Cell A is the serving cell. The LTM configuration of candidate cell B includes the configuration of cell B to be applied in the event of an LTM cell handover procedure to cell B. This configuration can be signaled by including an RRC reconfiguration IE for the candidate cell in the LTM configuration. This configuration includes a random access configuration but not a CFRA configuration. The random access configuration can be used for one or more uplink BWPs. The LTM configuration of candidate cell B can include a list of TCI states. Each TCI state can be associated with an RS (e.g., SSB or CSI RS or TRS). If cell A and cell B belong to different DUs of the same gNB, the gNB (or base station) 504 can obtain the configuration of cell B from the DU of cell B. When cell A and cell B belong to different DUs of different gNBs, cell A's gNB (or base station or CU) 504 can obtain cell B's configuration from cell B's gNB (or base station or CU) 506. The LTM configuration of candidate cell B may include L1 measurement configuration.

[0126] In step 515, UE 502 confirms the RRC configuration by sending an RRC reconfiguration complete message to gNB (or base station) 504 of cell A.

[0127] In step 520, UE 502 provides L1 and / or L3 measurement reports when performing measurements based on L1 and / or L3 measurement configuration.

[0128] In step 525, the gNB (or base station) 504 of cell A decides to perform an LTM cell handover to the target cell B, and in step 530, sends a MAC CE (or DCI) that triggers the cell handover by including the candidate configuration index of the target cell (i.e., cell B). (In step 510, the UE 502 may receive LTM configurations of multiple candidate cells, and each configuration is identified by a candidate configuration index). The cell handover command may include TCI status, preamble index, PUSCH timing index, TA, etc. If TA is not included, the preamble index / PUSCH timing index may be included. At step 535, the gNB (or base station) 504 of cell A provides cell handover information such as TCI status, preamble index, PUSCH timing index, etc., to the target cell B or to the gNB (or base station) 506 of the target cell B.

[0129] In step 540, UE 502 switches to target cell B and applies the configuration indicated by the candidate configuration index (in step 510, UE 502 may receive LTM configurations for multiple candidate cells, and each configuration is identified by a candidate configuration index). UE 502 completes the LTM cell handover process by sending an RRC reconfiguration complete message to target cell B.

[0130] In one embodiment, if the TA of target cell B is not available to UE 502 (e.g., it was not received in the handover command, or UE 502 itself has not estimated the TA, or it was not received before the handover command), then UE 502 may initiate a random access procedure to the target cell.

[0131] In one embodiment, UE 502 selects the SSB / CSIRS indicated in the cell handover command (MAC CE / DCI). In another embodiment, UE 502 selects the SSB / CSI RS corresponding to the TCI state received in the cell handover command (MAC CE / DCI). In yet another embodiment, UE 502 selects the SSB / CSI RS corresponding to the TCI state received in the cell handover command (MAC CE / DCI) if the RSRP of the SSB / CSI RS is greater than (or greater than or equal to) a configured threshold. In step 510, the mapping between the TCI state and the SSB / CSI RS is received from gNB 502. UE 502 selects the preamble indicated in the cell handover command. UE 502 selects the RACH timing (RO) corresponding to the selected SSB / CSI RS. In step 510, UE 502 receives the target cell configuration for the RO. UE 502 transmits the preamble in the selected RO. In one embodiment, the number of Msg1 repetitions can be received by UE 502, or indicated to UE 502 in the cell handover command (MAC CE / DCI) or as part of the LTM configuration of the target cell in step 510. If the number of Msg1 repetitions (N) is received / indicated, UE 502 transmits the selected preamble N times in a group of N ROs corresponding to the selected SSB / CSI RS. In the case of a two-step random access procedure, UE 502 can also transmit MsgA MACPDU (payload) to the target cell at the PUSCH timing. The index of the PUSCH timing can be indicated in the cell handover command. In step 510, UE 502 receives the target cell configuration of the PUSCH timing (PUSCH timing is indexed) for MsgA. The MsgA MAC PDU may include a C-RNTI MACCE and / or an RRC reconfiguration complete message. In the case of a 4-step random access procedure, UE 502 can send a Msg3 MAC PDU (payload) to the target cell in the UL grant received in the RAR. The Msg3 MAC PDU may include a C-RNTI MACCE and / or an RRC reconfiguration complete message.

[0132] Although Figure 5 An example procedure 500 for mobility triggered by a lower layer is shown, but it is possible to modify... Figure 5 Make various changes. For example, although it is displayed as a series of steps, Figure 5 The steps in the process can overlap, occur in parallel, occur in different orders, occur any number of times, be omitted, or be replaced by other steps.

[0133] Figure 6Another example process 600 for lower-level triggered mobility is shown according to an embodiment of this disclosure. Figure 6 The embodiments of the methods shown are for illustrative purposes only. Figure 6 One or more of the components shown can be implemented in a dedicated circuit configured to perform the function, or one or more of the components can be implemented by one or more processors that execute instructions to perform the function. Other embodiments for lower-level triggering mobility may be used without departing from the scope of this disclosure.

[0134] exist Figure 6 In the example, the process begins at step 610. In step 610, the gNB (or base station) 604 of cell A provides the LTM configuration of candidate cell B to UE 602. Cell A is the serving cell. The LTM configuration of candidate cell B includes the configuration of cell B to be applied in the event of an LTM cell handover procedure. This configuration can be signaled by including an RRC reconfiguration IE for the candidate cell in the LTM configuration. This configuration includes random access configurations (RO, PUSCH timing, etc.). This configuration may include a contention-free random access configuration, including a preamble index, and may also include a PUSCH timing index. The LTM configuration of candidate cell B may include a list of TCI states. Each TCI state may be associated with an RS (e.g., SSB, CSIRS, or TRS). If cell A and cell B belong to different DUs of the same gNB, the gNB (or base station) 604 can obtain the configuration of cell B from the DU of cell B. When cell A and cell B belong to different DUs of different gNBs, cell A's gNB (or base station or CU) 604 can obtain cell B's configuration from cell B's gNB (or base station or CU) 606. The LTM configuration of candidate cell B may include L1 measurement configuration.

[0135] In step 615, UE 602 confirms the RRC reconfiguration by sending an RRC reconfiguration completion message.

[0136] In step 620, the UE provides an L1 measurement report when performing measurements based on the L1 measurement configuration.

[0137] In step 625, the gNB (or base station) 604 of cell A decides to perform a cell handover to target cell B, and in step 630, sends a MAC CE (or DCI) triggering the cell handover by including a candidate configuration index of the target cell (i.e., cell B). (In step 610, the UE 602 may receive LTM configurations of multiple candidate cells, and each configuration is identified by a candidate configuration index). The cell handover command (MAC CE / DCI) may include TCI status, TA, etc. In step 635, the gNB (or base station) 604 of cell A provides cell handover information such as the TCI status to target cell B or the gNB (or base station) 606 of target cell B.

[0138] In step 640, UE 602 switches to target cell B and applies the configuration indicated by the candidate configuration index (in step 610, UE 602 may receive LTM configurations for multiple candidate cells, and each configuration is identified by a candidate configuration index). UE 604 completes the LTM cell handover process by sending an RRC reconfiguration complete message to target cell B.

[0139] In one embodiment, if the TA of target cell B is not available to UE 602 (e.g., it was not received in the handover command, or UE 602 itself has not estimated the TA, or it was not received before the handover command), then UE 602 may initiate a random access procedure to the target cell.

[0140] In one embodiment, UE 602 selects the SSB / CSIRS indicated in the cell handover command (MAC CE / DCI). In another embodiment, UE 602 selects the SSB / CSIRS corresponding to the TCI state received in the cell handover command. In yet another embodiment, UE 602 selects the SSB / CSI RS corresponding to the TCI state received in the cell handover command if the RSRP of the SSB / CSI RS is greater than (or greater than or equal to) a configured threshold. In step 610, the mapping between the TCI state and the SSB / CSI RS is received from gNB 604. UE 602 selects the preamble indicated in the CFRA configuration received in step 601. UE 602 selects the RACH timing (RO) corresponding to the selected SSB / CSI RS. In step 610, UE 602 receives the target cell configuration of the RO. UE 602 transmits the preamble in the selected RO. In one embodiment, the number of MSG1 repetitions can be received by UE 602, or indicated to UE 602 in the cell handover command or as part of the LTM configuration of the target cell in step 610. If the number of Msg1 repetitions (N) is received, the UE transmits the selected preamble N times in a group of N ROs corresponding to the selected SSB / CSIRS. In the case of a 2-step random access procedure, UE 602 can also transmit MsgA MAC PDU (payload) to the target cell during the PUSCH timing. The index of the PUSCH timing can be indicated in the CFRA configuration received in step 610. In step 610, UE 602 receives the target cell configuration for the PUSCH timing of MsgA (PUSCH timing is indexed). The MsgA MAC PDU may include a C-RNTI MAC CE and / or an RRC reconfiguration complete message. In the case of a 4-step random access procedure, UE 602 can transmit Msg3 MAC PDU (payload) to the target cell in the UL grant received in the RAR. Msg3 MAC PDU may include C-RNTI MAC CE and / or RRC reconfiguration complete messages.

[0141] Although Figure 6 An example procedure 600 for mobility triggered by a lower layer is shown, but it is possible to modify... Figure 6 Make various changes. For example, although it is displayed as a series of steps, Figure 6 The steps in the process can overlap, occur in parallel, occur in different orders, occur any number of times, be omitted, or be replaced by other steps.

[0142] Figure 7 Another example process 700 for lower-level triggered mobility is shown according to an embodiment of this disclosure. Figure 7 The embodiments of the methods shown are for illustrative purposes only. Figure 7 One or more of the components shown can be implemented in a dedicated circuit configured to perform the function, or one or more of the components can be implemented by one or more processors that execute instructions to perform the function. Other embodiments for lower-level triggering mobility may be used without departing from the scope of this disclosure.

[0143] exist Figure 6 In the example, the process begins at step 710. At step 710, the gNB (or base station) 704 of cell A provides the LTM configuration of candidate cell B to UE 702. Cell A is the serving cell. The LTM configuration of candidate cell B includes the configuration of cell B to be applied in the event of an LTM cell handover procedure. This configuration can be signaled by including an RRC reconfiguration IE for the candidate cell in the LTM configuration. This configuration includes random access configurations (RO, PUSCH timing, etc.). This configuration may include contention-free random access configurations, including a list of one or more of the preamble index, SSB / CSI RS index / ID, and / or PUSCH timing index. The LTM configuration of candidate cell B may include a list of TCI states. Each TCI state may be associated with an RS (e.g., SSB or CSI RS or TRS). If cell A and cell B belong to different DUs of the same gNB, the gNB (or base station) 704 can obtain the configuration of cell B from the DU of cell B. When cell A and cell B belong to different DUs of different gNBs, cell A's gNB (or base station or CU) 604 can obtain cell B's configuration from cell B's gNB (or base station or CU) 606. The LTM configuration of candidate cell B may include L1 measurement configuration.

[0144] In step 715, UE 702 confirms the RRC reconfiguration by sending an RRC reconfiguration complete message.

[0145] In step 720, UE 702 provides an L1 measurement report when performing measurements based on the L1 measurement configuration.

[0146] In step 725, the gNB (or base station) 704 of cell A decides to perform a cell handover to the target cell B, and in step 730, sends a MAC CE (or DCI) that triggers the cell handover, including a candidate configuration index of the target cell (i.e., cell B). The cell handover command may include TCI status, TA, etc. In step 735, the gNB (or base station) 704 of cell A provides cell handover information, such as the TCI status, to the target cell B or the gNB (or base station) 706 of the target cell B.

[0147] In step 740, UE 702 switches to target cell B and applies the configuration indicated by the candidate configuration index (in step 710, UE 702 may receive LTM configurations for multiple candidate cells, and each configuration is identified by a candidate configuration index). UE 702 completes the LTM cell handover process by sending an RRC reconfiguration complete message to target cell B.

[0148] In one embodiment, if the TA of target cell B is not available to UE 702 (e.g., it was not received in the handover command, or UE 702 itself has not estimated the TA, or it was not received before the handover command), then UE 702 may initiate a random access procedure to the target cell.

[0149] In one embodiment, UE 702 selects the SSB / CSIRS indicated in the cell handover command (MAC CE / DCI). In another embodiment, UE 702 selects the SSB / CSIRS corresponding to the TCI state received in the cell handover command. In yet another embodiment, UE 702 selects the SSB / CSIRS corresponding to the TCI state received in the cell handover command if the RSRP of the SSB / CSI RS is greater than (or greater than or equal to) a configured threshold. In step 710, the mapping between the TCI state and the SSB / CSI RS is received from gNB 704. UE 702 selects a preamble corresponding to the selected SSB / CSI RS indicated in the CFRA configuration received in step 710. UE 702 selects the RACH timing (RO) corresponding to the selected SSB / CSI RS. In step 710, the target cell configuration of the RO is received by UE 702. UE 710 transmits the preamble in the selected RO. In one embodiment, the number of Msg1 repetitions can be received by UE 702 in the cell handover command or as part of the LTM configuration of the target cell in step 2. If the number of Msg1 repetitions (e.g., N) is received, UE 702 transmits the selected preamble N times in the group of N ROs corresponding to the selected SSB / CSI RS. In the case of a 2-step random access procedure, UE 702 can also transmit MsgA MAC PDU (payload) to the target cell at the PUSCH timing. The index of the PUSCH timing can be indicated in the CFRA configuration received in step 710. In step 710, UE 702 receives the target cell configuration for the PUSCH timing of MsgA (PUSCH timing is indexed). The MsgA MAC PDU may include a C-RNTI MAC CE and / or an RRC reconfiguration complete message. In the case of a 4-step random access procedure, UE 702 can transmit Msg3 MAC PDU (payload) to the target cell in the UL grant received in the RAR. Msg3 MAC PDU may include C-RNTI MACCE and / or RRC reconfiguration complete message.

[0150] In another embodiment, UE 702 selects the SSB / CSI RS corresponding to the random access configuration index received in the cell handover command. The random access configuration index is the index of an entry in the CFRA configuration list received in step 710. In one embodiment, UE 702 selects the SSB / CSI RS corresponding to the random access configuration index received in the cell handover command if the RSRP of the SSB / CSI RS is greater than (or greater than or equal to) a configuration threshold. UE 702 selects a preamble corresponding to the selected SSB / CSI RS indicated in the CFRA configuration received in step 2. UE 702 selects the RACH timing (RO) corresponding to the selected SSB / CSI RS. In step 710, UE 702 receives the target cell configuration of the RO. UE 702 transmits the preamble in the selected RO. In one embodiment, the number of times Msg1 is repeated may be received by the UE in the cell handover command or in step 710 as part of the LTM configuration of the target cell. If Msg1 is received a number of times (N), UE 702 transmits the selected preamble N times in the group of N ROs corresponding to the selected SSB / CSI RS. In the case of a 2-step random access procedure, UE 702 may also transmit a MsgA MAC PDU (payload) to the target cell at the PUSCH timing. The index of the PUSCH timing may be indicated in the CFRA configuration received in step 710. In step 710, UE 702 receives the target cell configuration for the PUSCH timing of MsgA (the PUSCH timing is indexed). The MsgA MAC PDU may include a C-RNTI MAC CE and / or an RRC reconfiguration complete message. In the case of a 4-step random access procedure, UE 702 may transmit a Msg3 MAC PDU (payload) to the target cell in the UL grant received in the RAR. The Msg3 MAC PDU may include a C-RNTI MAC CE and / or an RRC reconfiguration complete message.

[0151] Although Figure 7 An example procedure 700 for mobility triggered by a lower layer is shown, but it is possible to modify... Figure 7 Make various changes. For example, although it is displayed as a series of steps, Figure 5 The steps in the process can overlap, occur in parallel, occur in different orders, occur any number of times, be omitted, or be replaced by other steps.

[0152] As previously described herein, Msg1 repetition can be beneficial for LTM cell handovers used for extended coverage. This disclosure provides a procedure for Msg1 repetition during LTM cell handovers.

[0153] In one embodiment, the RRC configuration (e.g., in...) Figure 4 The CFRA configuration (or 4-step CFRA configuration) of the LTM candidate cell / target cell (received by the UE in step 2) may include the number of times Msg1 is repeated (e.g., 2, 4, or 8). Upon receiving a cell handover command to the target cell (e.g., LTM cell handover command MAC CE or DCI), the UE uses the CFRA configuration of the target cell and performs a random access procedure for cell handover for the target cell. During the random access procedure, at each random access attempt, the UE repeats Msg1 before receiving the RAR, i.e., the preamble is sent (according to the number of Msg1 repetitions). At each RA attempt, a CFRA / CBRA with the indicated number of Msg1 repetitions is performed. If no Msg1 repetition is indicated and a CFRA configuration is received, the UE performs a CFRA / CBRA at each RA attempt without Msg1 repetition. If the cell handover command indicates an SSB / CSI RS associated with CFRA resources, or if the RSRP of the SSB / CSI RS associated with CFRA resources is higher than the configured threshold, the UE can choose CFRA (i.e., choose one of the contention-free preamble and / or RO configured in the CFRA configuration). Otherwise, the UE chooses CBRA (i.e., choose some of the contention-based preamble and / or RO configured in the random access configuration).

[0154] In one embodiment, RRC configuration (e.g. in...) Figure 4 The CFRA configuration (or 4-step CFRA configuration) of the LTM candidate cell / target cell (received by the UE in step 2) may include the number of Msg1 repetitions (e.g., 2, 4, or 8). Upon receiving a cell handover command (e.g., LTM cell handover command MAC CE or DCI), if the TA of target cell B is unavailable to the UE (e.g., not received in the handover command, or the UE has not yet estimated the TA, or the TA was not received before the handover command), the UE may initiate a random access procedure to the target cell. The UE checks whether the indicated Msg1 repetition count is met during cell handover.

[0155] If the indicated number of Msg1 repetitions is met, the UE performs a random access procedure for cell handover. During the random access procedure, at each random access attempt, the UE repeats Msg1 before receiving the RAR, i.e., the preamble is transmitted (according to the number of Msg1 repetitions). At each RA attempt, a CFRA / CBRA with the indicated number of Msg1 repetitions is performed. If the SSB / CSI RS associated with the CFRA resource is indicated in the cell handover command, or if the RSRP of the SSB / CSI RS associated with the CFRA resource is higher than the configured threshold, the UE can choose CFRA (i.e., choose one of the contention-free preamble and / or RO configured in the CFRA configuration). Otherwise, the UE chooses CBRA (i.e., choose one of the contention-based preamble and / or RO configured in the random access configuration).

[0156] If the indicated Msg1 repetition count criterion is not met, the UE does not use the CFRA configuration. The UE performs CBRA. The UE selects CBRA (i.e., selects one of the contention-based preamble and / or RO configured in the random access configuration). The repetition count can be selected based on a DL RSRP threshold (2, 4, 8). The threshold can be different for different repetition counts. If the Msg1 repetition criterion is not met, the UE performs CBRA on each RA attempt without Msg1 repetition.

[0157] In one embodiment, a CFRA configuration (or a 4-step CFRA configuration) for different Msg1 repetition numbers is included (e.g., in...). Figure 4In step 2, the LTM candidate cell / target cell configuration is received by the UE in the RRC configuration. The number of Msg1 repetitions to be applied is indicated in the LTM cell handover command MAC CE or DCI. Upon receiving the cell handover command, if the TA of target cell B is unavailable to the UE (e.g., not received in the handover command, or the UE has not yet estimated the TA, or the TA was not received before the handover command), the UE can initiate a random access procedure to the target cell. The UE selects the RACH configuration / CFRA configuration corresponding to the indicated number of Msg1 repetitions and executes the random access procedure for cell handover. A CFRA / CBRA with the indicated number of Msg1 repetitions is executed on each RA attempt. If no Msg1 repetition is indicated and a CFRA configuration is received, the UE executes a CFRA / CBRA on each RA attempt without Msg1 repetition. If the cell handover command indicates an SSB / CSI RS associated with CFRA resources, or if the RSRP of the SSB / CSI RS associated with CFRA resources is higher than the configured threshold, the UE can choose CFRA (i.e., choose one of the contention-free preamble and / or RO configured in the CFRA configuration). Otherwise, the UE chooses CBRA (i.e., choose one of the contention-based preamble and / or RO configured in the random access configuration).

[0158] In one embodiment, a CFRA configuration (or a 4-step CFRA configuration) for different Msg1 repetition numbers is included (e.g., in...). Figure 4In step 2, the LTM candidate cell / target cell configuration is received by the UE in the RRC configuration. Upon receiving a cell handover command, if the TA of target cell B is unavailable to the UE (e.g., not received in the handover command, or the UE has not yet estimated the TA, or the TA was not received before the handover command), the UE can initiate a random access procedure to the target cell. The UE determines the number of Msg1 repetitions to apply based on RSRP measurements (e.g., SS-RSRP). The number of repetitions (2, 4, 8) can be selected based on a DL RSRP threshold. The threshold can be different for different repetition numbers. If the DL RSRP is less than (or less than or equal to) the threshold for 8 repetitions, and the configuration for 8 repetitions is available for the RA procedure, the UE applies 8 repetitions. Otherwise, if the DL RSRP is less than (or less than or equal to) the threshold for 4 repetitions, and the configuration for 4 repetitions is available for the RA procedure, the UE applies 4 repetitions. Otherwise, if the DL RSRP is less than (or less than or equal to) the threshold for 2 repetitions, and the configuration for 2 repetitions is available for the RA procedure, the UE applies 2 repetitions. The UE then selects the CFRA / RACH configuration corresponding to the determined number of Msg1 repetitions and performs the random access procedure for cell handover. CFRA / CBRA with the indicated number of Msg1 repetitions is performed at each RA attempt. If no Msg1 repetition is indicated and a CFRA configuration is received, the UE performs CFRA / CBRA at each RA attempt without Msg1 repetition. If an SSB / CSI RS associated with the CFRA resource is indicated in the cell handover command, or if the RSRP of the SSB / CSI RS associated with the CFRA resource is higher than the configured threshold, the UE can select CFRA (i.e., select one of the contention-free preamble and / or RO configured in the CFRA configuration). Otherwise, the UE selects CBRA (i.e., select one of the contention-based preamble and / or RO configured in the random access configuration).

[0159] In existing wireless communication systems that support LTM, the UE receives an RRC reconfiguration message that includes RRC reconfigurations for one or more candidate LTM cells. The UE receives an LTM cell handover command (MAC CE) for the candidate LTM cells, and the UE applies the indicated RRC reconfiguration for the candidate LTM cells. The RRC reconfiguration includes dedicatedSIB1-Delivery. Upon receiving SIB1, the UE performs actions to process SIB1. This results in the generation and submission of an SI request.

[0160] Furthermore, the RRC reconfiguration message includes a ReconfigurationWithSync IE, and the UE executes the LTM configuration procedure. This triggers the generation and transmission of a reconfiguration completion message. However, according to the above operation, the transmission of the reconfiguration completion message will be delayed due to the presence of an SI request message in the SRB buffer. This disclosure provides a procedure to resolve this issue.

[0161] Figure 8 Another example process 800 for lower-level triggered mobility is shown according to an embodiment of this disclosure. Figure 8 The embodiments of the methods shown are for illustrative purposes only. Figure 8 One or more of the components shown can be implemented in a dedicated circuit configured to perform the function, or one or more of the components can be implemented by one or more processors that execute instructions to perform the function. Other embodiments of lower-layer triggered mobility may be used without departing from the scope of this disclosure.

[0162] exist Figure 8 In the example, the process begins at step 810. In step 810, the gNB (or base station) 802 of cell A provides the configuration of candidate cell B to UE 802. The configuration of candidate cell B may include L1 measurement configuration. Cell A is the serving cell and belongs to the MCG, and cell B is a candidate PCell or SpCell. The RRC reconfiguration IE for cell B is included in the RRC reconfiguration message received from the gNB (or base station) 804 of cell A. The RRC reconfiguration IE for cell B includes dedicatedSIB1-Delivery and ltm-Config IEs.

[0163] In step 820, UE 802 confirms the RRC reconfiguration received from gNB (or base station) 804 of cell A by sending an RRC reconfiguration completion message.

[0164] In step 830, after sending the RRC reconfiguration complete message, UE 1102 performs L1 measurements for cell B and reports these measurements to the gNB (or base station) 1102 to which cell A belongs.

[0165] In step 840, based on L1 measurement, the gNB (or base station) 1104 of cell A decides to perform an LTM cell handover to the target cell (i.e., cell B), and in step 850 sends a MAC CE that triggers the LTM cell handover by including the candidate configuration index of the target cell (i.e., cell B).

[0166] In step 860, UE 802 switches to target cell B and applies the configuration indicated by the candidate configuration index (i.e., the RRC reconfiguration IE for cell B received in step 810) (in step 1, the UE may receive LTM configurations for multiple candidate cells, and each configuration is identified by the candidate configuration index).

[0167] In one embodiment, if the applied RRC reconfiguration (for LTM execution) is associated with an MCG (i.e., target cell B belongs to the MCG) and includes ltm-Config and dedicatedSIB1-Delivery, then UE 802 will only (if necessary) initiate a request to obtain the SIBs required by cell B after the LTM execution on the target SpCell is successfully completed (step 870). dedicatedSIB1-Delivery includes the SIB1 of cell B and indicates which SIBs in cell B are periodically broadcast and which are not. For SIBs that are not periodically broadcast but are required in the RRC_CONNECTED state, UE 802 may send an SI request message to cell B. In this embodiment, UE 802 processes dedicatedSIB1-Delivery before ltm-Config. If UE 802 does not have a valid TA for the target cell, then UE 802 performs a random access procedure for target cell B. UE 802 completes the LTM cell handover procedure by sending an RRC reconfiguration complete message to target cell B. If UE 802 has performed the RA procedure, then UE 802 considers LTM execution to have been successfully completed when the random access procedure is successfully completed. For RACH-free LTM, UE 802 considers LTM execution to have been successfully completed when it determines that the network has successfully received its first uplink (UL) data (i.e., transmitted using a PUSCH with configured UL grant or dynamic UL grant). UE 802 determines the successful reception of its first UL data by receiving the PDCCH of the addressing UE's C-RNTI in the target cell, which schedules new transmissions (e.g., new UL transmissions or new downlink (DL) transport blocks / transmissions) following the first UL data.

[0168] In an alternative embodiment, if the RRC reconfiguration (for LTM execution) is associated with the MCG and includes ltm-Config and dedicatedSIB1-Delivery, then UE 802 processes ltm-Config before processing dedicatedSIB1-Delivery in the applied RRC reconfiguration.

[0169] Although Figure 8 An example procedure for mobility triggered by a lower layer is shown, but it is possible to modify it further. Figure 8Make various changes. For example, although it is displayed as a series of steps, Figure 8 The steps in the process can overlap, occur in parallel, occur in different orders, occur any number of times, be omitted, or be replaced by other steps.

[0170] In some embodiments, a handover command (or an RRC reconfiguration message with synchronized reconfiguration) may include an SSB index / CSI RS index and / or authorized (CG) resources for configuration of RACH-free handover (cell handover or reconfiguration with synchronized procedures).

[0171] In one embodiment, if an SSB index / CSI RS index is indicated, and a CG resource for RACH-free handover is configured in the handover command for the target cell (or an RRC reconfiguration message with synchronized reconfiguration), the UE selects the CG resource corresponding to the indicated SSB / CSI RS for initial UL transmission to the target cell. Otherwise, if no SSB index / CSI RS index is indicated, and a CG resource for RACH-free handover is configured, and at least one SSB / CSI RS associated with the CG resource has an RSRP greater than a threshold is available, the UE selects the CG resource corresponding to the SSB with an RSRP greater than the threshold for initial UL transmission to the target cell. If no SSB index / CSI RS index is indicated and no CG resource for RACH-free handover is configured, the UE performs a RACH-based handover (i.e., the UE initiates a random access procedure to the target cell). If the SSB index / CSI RS index is not indicated, and the CG resource for RACH-free handover is configured, and all SSB / CSI RS associated with the CG resource have RSRP less than a threshold, then the UE performs a RACH-based handover (i.e., the UE initiates a random access procedure to the target cell).

[0172] In another embodiment, if an SSB index / CSI RS index is indicated, and CG resources for RACH-free handover are configured in the handover command for the target cell (or an RRC reconfiguration message with synchronized reconfiguration), and the indicated SSB / CSI RS RSRP greater than a threshold is available, then the UE selects the CG resource corresponding to the indicated SSB for initial UL transmission to the target cell. Otherwise, if an SSB index / CSI RS index is not indicated, and CG resources for RACH-free handover are configured, and the associated SSB / CSI RS with an RSRP greater than a threshold is available, then the UE selects the CG resource corresponding to the SSB / CSI RS with an RSRP greater than the threshold for initial UL transmission to the target cell. If an SSB index / CSI RS index is indicated, and CG resources for RACH-free handover are configured in the handover command for the target cell (or an RRC reconfiguration message with synchronized reconfiguration), and the RSRP of the indicated SSB / CSI RS is less than a threshold, the UE performs a RACH-based handover (i.e., the UE initiates a random access procedure to the target cell). If no SSB index / CSI RS index is indicated and no CG resources for RACH-free handover are configured, the UE performs a RACH-based handover (i.e., the UE initiates a random access procedure to the target cell). If no SSB index / CSI RS index is indicated, and CG resources for RACH-free handover are configured, and all SSBs associated with the CG resources have RSRPs less than a threshold, the UE performs a RACH-based handover (i.e., the UE initiates a random access procedure to the target cell).

[0173] In one embodiment, when initiating a random access procedure, the UE selects one or more random access resource sets / configurations that support Msg1 repetition and sets RA_TYPE to 4-stepRA-Msg1Repetition (i.e., Msg1 repetition is applied to the random access procedure). These random access resource sets / configurations support the same feature / feature combination applicable to the random access procedure (features may include SDT, RedCap, Msg3 repetition, slicing, etc.). The random access resource sets / configurations that support Msg1 repetition may support 2 and / or 4 and / or 8 Msg1 repetitions. The UE selects the applicable number of Msg1 repetitions for the random access procedure. This selection can be performed using the downlink (DL) RSRP. For example, if the DLRSRP is less than (or less than or equal to) a threshold of 8 repetitions, and the selected random access resource set / configuration supports 8 repetitions, then 8 repetitions are applicable to the random access procedure. If the DL RSRP is less than (or less than or equal to) the threshold of 4 repetitions, and the selected random access resource set / configuration supports 4 repetitions, then 4 repetitions apply to the random access procedure. If the DL RSRP is less than (or less than or equal to) the threshold of 2 repetitions, and the selected random access resource set / configuration supports 2 repetitions, then 2 repetitions apply to the random access procedure. When multiple Msg1 repetition counts are applicable to the random access procedure, the UE selects the smallest applicable Msg1 repetition count. The Msg1 repetition count can be notified by gNB signaling, for example, in the case of contention-free random access for handover / reconfiguration with synchronization. The gNB notifies TransMax-Msg1RepNum via signaling for fallback from a lower Msg1 repetition count to a higher count.

[0174] In one embodiment, the UE sends an RA preamble and listens for RAR during the RAR window. Upon receiving RAR, the UE sends Msg3 and starts a contention resolution timer. During the random access procedure, if the contention resolution timer expires, the UE considers the contention resolution unsuccessful and increments PREAMBLE_TRANSMISSION_COUNTER by 1. If PREAMBLE_TRANSMISSION_COUNTER = preambleTransMax + 1, the UE indicates a random access problem to the upper layer. If the random access procedure was triggered in response to an SI request, the UE considers the random access procedure to have failed.

[0175] If the random access process is not completed:

[0176] - In one embodiment, if RA_TYPE is set to 4-step RA-Msg1Repetition (i.e., Msg1 repetition applies) for the random access procedure, and no contention-free random access resources are not signaled / unavailable, if PREAMBLE_TRANSMISSION_COUNTER = TransMax-Msg1RepNum, or if PREAMBLE_TRANSMISSION_COUNTER = 2*TransMax-Msg1RepNum + 1, and if the random access resource set for the random access procedure (i.e., the set supporting the same features / feature combinations) is configured with a higher number of Msg1 repetitions than the currently applied number of Msg1 repetitions for the random access procedure, then the UE selects / applies the next higher number of Msg1 repetitions for the random access procedure. For example, if the currently applied number of Msg1 repetitions is 2, and the random access resource set(s) for the random access procedure supports 2, 4, and 8 repetitions, then the UE will apply the next higher number of Msg1 repetitions, i.e., 4 repetitions. In another example, if the currently applied Msg1 repeats 4 times, and the random access resource set(s) selected for the random access procedure supports 2 and 4 repeats, then the UE continues to apply 4 repeats.

[0177] - In another embodiment, if for the random access procedure, RA_TYPE is set to 4-stepRA-Msg1Repetition (i.e., Msg1 repetition applies), and no contention-free random access resources are not signaled / unavailable, and the PRACH transmission power of the last preamble transmission during the random access procedure is the maximum value that the UE can transmit (or the PREAMBLE_RECEIVED_TARGET_POWER of the last preamble transmission during the random access procedure is greater than the configured threshold), if PREAMBLE_TRANSMISSION_COUNTER = TransMax-Msg1RepNum + 1 or if PREAMBLE_TRANSMISSION_COUNTER = 2*TransMax-Msg1RepNum + 1, and if the random access resource set for the random access procedure (i.e., the set supporting the same features / feature combinations) is configured with a higher Msg1 repetition count than the Msg1 repetition count currently applied for the random access procedure, then the UE selects / applies the next higher Msg1 repetition count for the random access procedure. For example, if the currently applied Msg1 repetition count is 2, and the random access resource sets(s) selected for this random access procedure support 2, 4, and 8 repetitions, then the UE will apply the next higher Msg1 repetition count (i.e., 4 repetitions) and use a random access resource set that supports 4 repetitions. In another example, if the currently applied Msg1 repetition count is 4, and the random access resource sets(s) selected for this random access procedure support 2 and 4 repetitions, then the UE will continue to apply 4 repetitions.

[0178] - In another embodiment, if for the random access procedure, RA_TYPE is set to 4-step RA-Msg1Repetition (i.e., Msg1 is repeatedly applied) (alternatively, RA_TYPE is set to 4-step RA-Msg1Repetition [i.e., Msg1 is repeatedly applied]), and the PRACH transmit power of the last preamble transmission during the random access procedure is the maximum value that the UE can transmit (or the PREAMBLE_RECEIVED_TARGET_POWER of the last preamble transmission during the random access procedure is greater than the configured threshold), if PREAMBLE_TRANSMISSION_COUNTER = TransMax-Msg1RepNum + 1 or if PREAMBLE_TRANSMISSION_COUNTER = 2*TransMax-Msg1RepNum +1. If the random access resource set (i.e., the set supporting the same features / combinations) for this random access procedure is configured with a higher Msg1 repetition count than the currently applied Msg1 repetition count for this random access procedure, the UE selects / applies the next higher Msg1 repetition count for this random access procedure. For example, if the currently applied Msg1 repetition count is 2, and the random access resource set(s) for this random access procedure supports 2, 4, and 8 repetitions, the UE will apply the next higher Msg1 repetition count (i.e., 4 repetitions) and use the random access resource set that supports 4 repetitions. In another example, if the currently applied Msg1 repetition count is 4, and the random access resource set(s) selected for this random access procedure supports 2 and 4 repetitions, the UE continues to apply 4 repetitions. If contention-free random access resources are configured for this random access procedure, the UE discards those contention-free random access resources. The MAC entity will release or stop using those resources during the random access procedure.

[0179] - In another embodiment, if for the random access procedure, RA_TYPE is set to 4-stepRA-Msg1Repetition (i.e., Msg1 repetition applies) (alternatively, RA_TYPE is set to 4-stepRA-Msg1Repetition [i.e., Msg1 repetition applies]), and the PRACH transmit power of the last preamble transmission during the random access procedure is the maximum value that the UE can transmit (or the PREAMBLE_RECEIVED_TARGET_POWER of the last preamble transmission during the random access procedure is greater than the configured threshold), if PREAMBLE_TRANSMISSION_COUNTER = TransMax-Msg1RepNum + 1 or if PREAMBLE_TRANSMISSION_COUNTER = 2*TransMax-Msg1RepNum + 1, and if the criteria for selecting a contention-free random access resource are met (for the next RA attempt), then the UE selects / applies the number of Msg1 repetitions indicated in the contention-free random access resource configuration received from the gNB. Otherwise, if the random access resource set (i.e., the set supporting the same features / combinations) for the random access procedure is configured with a higher number of Msg1 repetitions than the currently applied Msg1 repetitions for the random access procedure, the UE selects / applies the next higher number of Msg1 repetitions for the random access procedure. For example, if the currently applied Msg1 repetitions are 2, and the random access resource set(s) selected for the random access procedure supports 2, 4, and 8 repetitions, the UE will apply the next higher number of Msg1 repetitions (i.e., 4 repetitions) and use a random access resource set that supports 4 repetitions. In another example, if the currently applied Msg1 repetitions are 4, and the random access resource set(s) selected for the random access procedure supports 2 and 4 repetitions, the UE continues to apply 4 repetitions.

[0180] - In another embodiment, if for the random access procedure, RA_TYPE is set to 4-stepRA-Msg1Repetition (i.e., Msg1 repetition applies) (alternatively, RA_TYPE is set to 4-stepRA-Msg1Repetition [i.e., Msg1 repetition applies]), and the PRACH transmit power of the last preamble transmission during the random access procedure is the maximum value that the UE can transmit (or the PREAMBLE_RECEIVED_TARGET_POWER of the last preamble transmission during the random access procedure is greater than the configured threshold), if PREAMBLE_TRANSMISSION_COUNTER = TransMax-Msg1RepNum + 1 or PREAMBLE_TRANSMISSION_COUNTER = 2*TransMax-Msg1RepNum + 1, and if the criteria for selecting a contention-free random access resource (for the next RA attempt) are met, then the UE selects / applies the number of Msg1 repetitions indicated in the contention-free random access resource configuration received from the gNB. Otherwise, if the random access resource set for the random access procedure (i.e., the set supporting the same features / combinations of features) is configured with a higher Msg1 repetition count than the currently applied Msg1 repetition count for the random access procedure, the UE selects / applies the next higher Msg1 repetition count for the random access procedure. For example, if the currently applied Msg1 repetition count is 2, and the random access resource set(s) selected for the random access procedure supports 2, 4, and 8 repetitions, the UE will apply the next higher Msg1 repetition count (i.e., 4 repetitions) and use the random access resource set that supports 4 repetitions. In another example, if the currently applied Msg1 repetition count is 4, and the random access resource set(s) selected for the random access procedure supports 2 and 4 repetitions, the UE continues to apply 4 repetitions. If contention-free random access resources are configured for the random access procedure, the UE discards those contention-free random access resources. The MAC entity will release or stop using those resources during the random access procedure. The UE selects a random backoff time based on a uniform distribution between 0 and PREAMBLE_BACKOFF. If the criteria for selecting a contention-free random access resource are met during the backoff time, the UE performs the random access resource selection procedure and sends a random access preamble. Otherwise, the UE performs the random access resource selection procedure and sends a random access preamble after the backoff time ends.

[0181] In one embodiment, the UE sends a RA preamble and listens for RAR during the RAR window. During the random access procedure, if the RAR window expires and no RAR is received, the UE considers the random access response reception unsuccessful and increments PREAMBLE_TRANSMISSION_COUNTER by 1. If PREAMBLE_TRANSMISSION_COUNTER = preambleTransMax + 1, then if a random access preamble is sent on the SpCell, the UE indicates a random access problem to the upper layer. If the random access procedure was triggered in response to an SI request, the UE considers the random access procedure unsuccessfully completed. Otherwise, if a random access preamble is sent on the SCell, the UE considers the random access procedure unsuccessfully completed.

[0182] If the random access process is not completed:

[0183] - In one embodiment, if for the random access procedure, RA_TYPE is set to 4-stepRA-Msg1Repetition (i.e., Msg1 repetition is applied), and no contention-free random access resources are not signaled / unavailable, if PREAMBLE_TRANSMISSION_COUNTER = TransMax-Msg1RepNum, or if PREAMBLE_TRANSMISSION_COUNTER = 2*TransMax-Msg1RepNum + 1, and if the random access resource set for the random access procedure (i.e., the set supporting the same features / feature combinations) is configured with a higher Msg1 repetition count than the Msg1 repetition count currently applied for the random access procedure, then the UE selects / applies the next higher Msg1 repetition count for the random access procedure. For example, if the currently applied Msg1 repetition count is 2, and the random access resource sets(s) selected for this random access procedure support 2, 4, and 8 repetitions, then the UE will apply the next higher Msg1 repetition count (i.e., 4 repetitions) and use a random access resource set that supports 4 repetitions. In another example, if the currently applied Msg1 repetition count is 4, and the random access resource sets(s) selected for this random access procedure support 2 and 4 repetitions, then the UE will continue to apply 4 repetitions.

[0184] - In another embodiment, if for the random access procedure, RA_TYPE is set to 4-step RA-Msg1Repetition (i.e., Msg1 is repeatedly applied), and the contention-free random access resource is not signaled / unavailable, and the PRACH transmit power of the last preamble transmission during the random access procedure is the maximum value that the UE can transmit (or the PREAMBLE_RECEIVED_TARGET_POWER of the last preamble transmission during the random access procedure is greater than the configured threshold), if PREAMBLE_TRANSMISSION_COUNTER = TransMax-Msg1RepNum + 1 or if PREAMBLE_TRANSMISSION_COUNTER = 2*TransMax-Msg1RepNum + 1 1. If the random access resource set (i.e., the set supporting the same features / combinations of features) for the random access procedure is configured with a higher Msg1 repetition count than the currently applied Msg1 repetition count for the random access procedure, then the UE selects / applies the next higher Msg1 repetition count for the random access procedure. For example, if the currently applied Msg1 repetition count is 2, and the random access resource set(s) selected for the random access procedure supports 2, 4, and 8 repetitions, then the UE will apply the next higher Msg1 repetition count (i.e., 4 repetitions) and use a random access resource set that supports 4 repetitions. In another example, if the currently applied Msg1 repetition count is 4, and the random access resource set(s) selected for the random access procedure supports 2 and 4 repetitions, then the UE continues to apply 4 repetitions.

[0185] - In another embodiment, if RA_TYPE is set to 4-step RA-Msg1Repetition (i.e., Msg1 is repeatedly applied) (alternatively, RA_TYPE is set to 4-step RA-Msg1Repetition [i.e., Msg1 is repeatedly applied]), and the PRACH transmit power of the last preamble transmission during the random access procedure is the maximum value that the UE can transmit (or the PREAMBLE_RECEIVED_TARGET_POWER of the last preamble transmission during the random access procedure is greater than the configured threshold), if PREAMBLE_TRANSMISSION_COUNTER = TransMax-Msg1RepNum + 1 or if PREAMBLE_TRANSMISSION_COUNTER = 2*TransMax-Msg1RepNum + 1 1. If the random access resource set (i.e., the set supporting the same features / combinations) for the random access procedure is configured with a higher Msg1 repetition count than the currently applied Msg1 repetition count for the random access procedure, the UE selects / applies the next higher Msg1 repetition count for the random access procedure. For example, if the currently applied Msg1 repetition count is 2, and the random access resource set(s) selected for the random access procedure supports 2, 4, and 8 repetitions, the UE will apply the next higher Msg1 repetition count (i.e., 4 repetitions) and use the random access resource set that supports 4 repetitions. In another example, if the currently applied Msg1 repetition count is 4, and the random access resource set(s) selected for the random access procedure supports 2 and 4 repetitions, the UE continues to apply 4 repetitions. If contention-free random access resources are configured for the random access procedure, the UE discards those contention-free random access resources. The MAC entity will release or stop using those resources during the random access procedure.

[0186] - In another embodiment, if RA_TYPE is set to 4-stepRA-Msg1Repetition (i.e., Msg1 repetition applies) (alternatively, RA_TYPE is set to 4-stepRA-Msg1Repetition [i.e., Msg1 repetition applies]), and the PRACH transmit power of the last preamble transmission during the random access procedure is the maximum value that the UE can transmit (or the PREAMBLE_RECEIVED_TARGET_POWER of the last preamble transmission during the random access procedure is greater than the configured threshold), if PREAMBLE_TRANSMISSION_COUNTER = TransMax-Msg1RepNum + 1 or if PREAMBLE_TRANSMISSION_COUNTER = 2*TransMax-Msg1RepNum + 1, and if the criteria for selecting a contention-free random access resource (for the next RA attempt) are met, then the UE selects / applies the number of Msg1 repetitions indicated in the contention-free random access resource configuration received from the gNB. Otherwise, if the random access resource set for the random access procedure (i.e., the set supporting the same features / combinations of features) is configured with a higher number of Msg1 repetitions than the currently applied Msg1 repetitions for the random access procedure, the UE selects / applies the next higher number of Msg1 repetitions for the random access procedure. For example, if the currently applied Msg1 repetitions are 2, and the random access resource sets(s) selected for the random access procedure support 2, 4, and 8 repetitions, the UE will apply the next higher number of Msg1 repetitions (i.e., 4 repetitions) and use a random access resource set that supports 4 repetitions. In another example, if the currently applied Msg1 repetitions are 4, and the random access resource sets(s) selected for the random access procedure support 2 and 4 repetitions, the UE continues to apply 4 repetitions.

[0187] In another embodiment, if RA_TYPE is set to 4-step RA-Msg1Repetition (i.e., Msg1 repetition applies) (alternatively, RA_TYPE is set to 4-step RA-Msg1Repetition (i.e., Msg1 repetition applies)), and the PRACH transmit power of the last preamble transmission during the random access procedure is the maximum value that the UE can transmit (or the PREAMBLE_RECEIVED_TARGET_POWER of the last preamble transmission during the random access procedure is greater than the configured threshold), if PREAMBLE_TRANSMISSION_COUNTER = TransMax-Msg1RepNum + 1 or if PREAMBLE_TRANSMISSION_COUNTER = 2*TransMax-Msg1RepNum + 1, and if the criteria for selecting a contention-free random access resource (for the next RA attempt) are met, then the UE selects / applies the number of Msg1 repetitions indicated in the contention-free random access resource configuration received from the gNB. Otherwise, if the random access resource set for the random access procedure (i.e., the set supporting the same features / combinations of features) is configured with a higher Msg1 repetition count than the currently applied Msg1 repetition count for the random access procedure, the UE selects / applies the next higher Msg1 repetition count for the random access procedure. For example, if the currently applied Msg1 repetition count is 2, and the random access resource set(s) selected for the random access procedure supports 2, 4, and 8 repetitions, the UE will apply the next higher Msg1 repetition count (i.e., 4 repetitions) and use the random access resource set that supports 4 repetitions. In another example, if the currently applied Msg1 repetition count is 4, and the random access resource set selected for the random access procedure supports 2 and 4 repetitions, the UE continues to apply 4 repetitions. If contention-free random access resources are configured for the random access procedure, the UE discards those contention-free random access resources. The MAC entity will release or deactivate those resources during the random access procedure. The UE selects a random backoff time based on a uniform distribution between 0 and PREAMBLE_BACKOFF. If the criteria for selecting a contention-free random access resource are met during the backoff time, the UE performs a random access resource selection procedure. Otherwise, if the random access procedure for a SCell is performed on an uplink carrier where a pusch-Config is not configured, the UE delays subsequent random access transmissions until the random access procedure is triggered by a PDCCH command with the same ra-PreambleIndex, ra-ssb-OccasionMaskIndex, and UL / SUL indicators. Otherwise, the UE performs a random access resource selection procedure after the backoff time ends.

[0188] In some embodiments, the following criteria are met for selecting contention-free random access resources:

[0189] The criterion is satisfied if the random access procedure is initiated for SpCell beam failure recovery, and if beamFailureRecoveryTimer is running or not configured, and if the contention-free random access resource for the beam failure recovery request associated with any of the SSBs and / or CSI-RS has been explicitly provided by the RRC, and if at least one of the SSBs in the candidateBeamRSList with an SS-RSRP higher than rsrp-ThresholdSSB or the CSI-RS in the candidateBeamRSList with a CSI-RSRP higher than rsrp-ThresholdCSI-RS is available.

[0190] Otherwise, the standard is satisfied if ra-PreambleIndex is explicitly provided by PDCCH and if ra-PreambleIndex is not 0b000000.

[0191] The criterion is satisfied if contention-free random access resources associated with an SSB are explicitly provided in rach-ConfigDedicated (i.e., received from the gNB, for example, via RRC signaling messages), and at least one of the associated SSBs with an SS-RSRP higher than rsrp-ThresholdSSB is available.

[0192] Otherwise, the criterion is satisfied if a contention-free random access resource associated with a CSI-RS is explicitly provided in rach-ConfigDedicated (i.e., received from the gNB, for example, via an RRC signaling message), and at least one of the associated CSI-RSs with a CSI-RSRP higher than rsrp-ThresholdCSI-RS is available.

[0193] In one embodiment, when a CFRA resource with a number of repetitions is configured, the following are options for rollback at the end of an unsuccessful RA attempt.

[0194] Option 1: If the criteria for falling back to a higher number of repetitions are met (i.e., the number of Msg1 retransmissions has reached the configured value), the UE selects a higher number of repetitions. If the UE falls back to a higher number of repetitions than configured for CFRA, the CFRA resource can be considered to have been released from the MAC. Note that the UE cannot select CFRA for this RA attempt or subsequent RA attempts because fallback from higher to lower number of repetitions is not supported.

[0195] Option 2: If the criteria for falling back to a higher repetition count are met (i.e., the number of Msg1 retransmissions has reached the configured value), and the criteria for selecting CFRA are not met, then the UE selects a higher repetition count. If the UE falls back to a higher repetition count, the UE cannot select CFRA for that RA attempt or subsequent RA attempts because fallback from higher to lower repetition counts is not supported. CFRA resources can be considered to be released from the MAC.

[0196] Option 3: If the criteria for falling back to a higher repetition count are met (i.e., the number of Msg1 retransmissions has reached the configured value), and the criteria for selecting CFRA are not met, then the UE selects a higher repetition count. If the criteria for selecting CFRA are met, then the UE selects the repetition count configured for CFRA.

[0197] In one embodiment, the UE is configured with a PSCell. The PSCell is active and configured / associated with two tags (e.g., TAG1 and TAG2). The UE maintains a separate timeAlignment timer instance for each of these two tags. When the UE receives a TA for a tag from the GNB, it starts the timeAlignmentTimer instance for that tag. The PSCell is deactivated upon receiving a deactivation command from the gNB. Subsequently, the gNB sends an RRC reconfiguration message to activate the PSCell. Upon receiving the RRC reconfiguration message to activate the PSCell, the UE checks whether at least one of the timeAlignmentTimer instances associated with the PSCell's tag (or primary tag [PTAG]) is running. If the PSCell is configured with two tags, and neither of the timeAlignmentTimers for these tags is running, the UE initiates a random access procedure to the PSCell. If the PSCell is configured with one tag, and the timeAlignmentTimer for that tag is not running, the UE initiates a random access procedure to the PSCell.

[0198] In another embodiment, the UE is configured with a PSCell. The PSCell is active and configured / associated with two tags (e.g., TAG1 and TAG2). One of these tags may be referred to as the first tag, and the other as the second tag. The tag with the smaller tag ID value may be referred to as the first tag. The UE maintains a separate timeAlignment timer instance for each of these two tags. When the UE receives a TA for a tag from the GNB, it starts the timeAlignmentTimer instance for that tag. The PSCell is deactivated upon receiving a deactivation command from the gNB. Subsequently, the gNB sends an RRC reconfiguration message to activate the PSCell. Upon receiving the RRC reconfiguration message to activate the PSCell, the UE checks whether at least one of the timeAlignmentTimers associated with the PSCell's tag (or PTAG) is running. If the PSCell is configured with two tags, and the timeAlignmentTimer instance for the first tag (or the tag with the smaller tag ID value of the two tags) is not running, the UE initiates a random access procedure to the PSCell. Alternatively, if the PSCell is configured with two tags, and the timeAlignmentTimer instance for the second tag (or the tag with the larger tag ID value of the two tags) is not running, the UE initiates a random access procedure to the PSCell. If the PSCell is configured with one tag and the timeAlignmentTimer for that tag is not running, the UE initiates a random access procedure to the PSCell.

[0199] In one embodiment, the UE can be in the RRC_CONNECTED state and perform sidelink (SL) communication. The UE receives an SL grant for sidelink communication. The UE uses the SL grant of another UE on the sidelink to transmit to the SLMAC PDU (on the PSSCH). The UE receives HARQ feedback from another UE (on the PSFCH) for transmission. The UE can be configured by sl-PUCCH-Config, which indicates the PUCCH resources used to send feedback for sidelink communication to the GNB. If sl-PUCCH-Config is configured, the UE sends HARQ feedback to the gNB at the PUCCH transmission time when it receives feedback for sidelink transmission from another UE on the PSSCH.

[0200] According to existing operations, for PSSCH transmission, if sl-PUCCH-Config is configured, and if the timeAlignmentTimer associated with the serving cell containing the HARQ feedback to be transmitted thereon stops or expires, the UE does not instruct the physical layer to generate multiple acknowledgments (ACKs) for the data in the TB.

[0201] The serving cell that sends HARQ feedback for PSSCH can be configured with two TAGs (e.g., TAG1 and TAG2). One of these TAGs can be referred to as the first TAG, and the other as the second TAG. The TAG with the smaller TAG ID value can be referred to as the first TAG. The UE maintains a separate timeAlignment timer instance for each of these two TAGs. When the UE receives a TA for the TAG from the GNB, it starts the timeAlignmentTimer instance for that TAG.

[0202] The problem with existing operations is that if the timeAlignmentTimer associated with the serving cell's TAG on which HARQ feedback is to be sent stops or expires, the UE does not send HARQ feedback. This is inefficient because another timeAlignmentTimer for the serving cell may still be running. This disclosure provides a procedure to address these inefficiencies.

[0203] In one embodiment, the UE uses the SL authorization of another UE on the sidelink to transmit to the SL MACPDU (on the PSSCH). The UE (on the PSFCH) receives HARQ feedback from the other UE for transmission. For PSSCH transmission, if sl-PUCCH-Config is configured, and if the serving cell on which HARQ feedback is to be transmitted is configured with two TAGs, and if the two timeAlignmentTimer instances associated with the TAG of the serving cell on which HARQ feedback is to be transmitted are stopped or expired, the UE does not instruct the physical layer to generate multiple acknowledgments for the data in the TB.

[0204] In one embodiment, the UE uses the SL authorization of another UE on the sidelink to transmit to the SL MACPDU (on the PSSCH). The UE (on the PSFCH) receives HARQ feedback from the other UE for transmission. For PSSCH transmission, if sl-PUCCH-Config is configured, and if the serving cell on which HARQ feedback is to be transmitted is configured with two TAGs, and if the timeAlignmentTimer instance associated with the first (or the TAG with the smaller TAG ID value of the two TAGs) of the serving cell on which HARQ feedback is to be transmitted stops or expires, the UE does not instruct the physical layer to generate multiple acknowledgments for the data in the TB.

[0205] In one embodiment, the UE uses the SL authorization of another UE on the sidelink to transmit to the SL MACPDU (on the PSSCH). The UE receives HARQ feedback from the other UE (on the PSFCH) for transmission. For PSSCH transmission, if sl-PUCCH-Config is configured, and if the serving cell on which HARQ feedback is to be transmitted is configured with two TAGs, and if the timeAlignmentTimer instance associated with the second TAG (or the TAG with the larger TAG ID value of the two TAGs) of the serving cell on which HARQ feedback is to be transmitted stops or expires, the UE does not instruct the physical layer to generate multiple acknowledgments for the data in the TB.

[0206] In one embodiment, the UE uses the SL authorization of another UE on the sidelink to transmit to the SL MACPDU (on the PSSCH). The UE (on the PSFCH) receives HARQ feedback from the other UE for transmission. For PSSCH transmission, if sl-PUCCH-Config is configured, and if the serving cell on which HARQ feedback is to be transmitted is configured with two TAGs (one PTAG and the other a secondary TAG [STAG]), and if the timeAlignmentTimer associated with the PTAG of the serving cell on which HARQ feedback is to be transmitted stops or expires, the UE does not instruct the physical layer to generate multiple acknowledgments for the data in the TB.

[0207] Figure 9 An example method 900 for lower-layer triggered mobility is shown according to an embodiment of the present disclosure. Figure 9 The embodiments of the methods shown are for illustrative purposes only. Figure 9One or more of the components shown can be implemented in a dedicated circuit configured to perform the function, or one or more of the components can be implemented by one or more processors that execute instructions to perform the function. Other embodiments for lower-level triggering mobility may be used without departing from the scope of this disclosure.

[0208] exist Figure 9 In the example, the method begins at step 910. In step 910, the UE (e.g., Figure 1 UE 116 receives an RRC reconfiguration message including configuration for at least one LTM candidate cell. In step 920, the UE receives an LTM cell handover command MAC CE, which instructs the UE to perform an LTM cell handover to an LTM candidate cell with the configuration included in the RRC reconfiguration message. In step 930, the UE sends a random access preamble to the LTM candidate cell indicated by the MAC CE for a total of N repetitions. In step 940, the UE listens to the PDCCH in response to the random access response.

[0209] Although Figure 9 An example method 900 for mobility triggered by a lower layer is shown, but it is possible to modify... Figure 9 Make various changes. For example, although it is displayed as a series of steps, Figure 9 The steps in the process can overlap, occur in parallel, occur in different orders, occur any number of times, be omitted, or be replaced by other steps.

[0210] Figure 10 A block diagram of a terminal (or user equipment (UE)) according to an embodiment of the present disclosure is shown.

[0211] like Figure 10 As shown, the terminal according to the embodiment may include a transceiver 1010, a memory 1020, and a processor (or controller) 1030. The transceiver 1010, memory 1020, and processor (or controller) 1030 of the terminal can operate according to the communication method of the terminal described above. However, the components of the terminal are not limited thereto. For example, the terminal may include... Figure 10 The components described herein may include more or fewer components. Furthermore, the processor (or controller) 1030, transceiver 1010, and memory 1020 may be implemented as a single chip. Additionally, the processor (or controller) 1030 may include at least one processor.

[0212] Transceiver 1010 generally refers to both a terminal station receiver and a terminal transmitter, and can transmit signals to or receive signals from a base station or another terminal. Signals transmitted to or received from a terminal may include control information and data. Transceiver 1010 may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for low-noise amplification and down-converting the frequency of the received signal. However, this is merely an example of transceiver 1010, and the components of transceiver 1010 are not limited to RF transmitters and RF receivers.

[0213] Furthermore, the transceiver 1010 can receive signals via a wireless channel and output them to the processor (or controller) 1030, and can also transmit signals output from the processor (or controller) 1030 via a wireless channel.

[0214] The memory 1020 can store programs and data required for the operation of the terminal. Furthermore, the memory 1020 can store control information or data included in signals received by the terminal. The memory 1020 can be a storage medium such as a read-only memory (ROM), random access memory (RAM), hard disk, CD-ROM, and DVD, or a combination of storage media.

[0215] The processor (or controller) 1030 can control a series of processes to cause the terminal to operate as described above. For example, the processor (or controller) 1030 can receive data signals and / or control signals, and the processor (or controller) 1030 can determine the result of receiving signals transmitted by the base station and / or other terminals.

[0216] Figure 11 A block diagram of a base station according to an embodiment of the present disclosure is shown.

[0217] like Figure 11 As shown, the base station of this disclosure may include a transceiver 1110, a memory 1120, and a processor (or controller) 1130. The transceiver 1110, memory 1120, and processor (or controller) 1130 of the base station can operate according to the communication method of the base station described above. However, the components of the base station are not limited thereto. For example, the base station may include... Figure 11 The components described herein may include more or fewer components. Furthermore, the processor (or controller) 1130, transceiver 1110, and memory 1120 may be implemented as a single chip. Additionally, the processor (or controller) 1130 may include at least one processor.

[0218] Transceiver 1110 generally refers to both a base station receiver and a base station transmitter, and can transmit / receive signals to / from a terminal, another base station, and / or (multiple) core network functions (or (multiple) entities). Signals transmitted to or received from a base station may include control information and data. Transceiver 1110 may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for low-noise amplification and down-converting the frequency of the received signal. However, this is merely an example of transceiver 1110, and the components of transceiver 1110 are not limited to RF transmitters and RF receivers.

[0219] Furthermore, the transceiver 1110 can receive signals via a wireless channel and output them to the processor (or controller) 1130, and can also transmit signals output from the processor (or controller) 1130 via a wireless channel.

[0220] The memory 1120 can store programs and data required for the operation of the base station. Furthermore, the memory 1120 can store control information or data included in signals acquired by the base station. The memory 1120 can be a storage medium such as ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media.

[0221] The processor (or controller) 1130 can control a series of processes to enable the base station to operate as described above. For example, the processor (or controller) 1130 can receive data signals and / or control signals, and the processor (or controller) 1130 can determine the result of receiving signals sent by the terminal and / or core network functions.

[0222] When electrical structures and methods are implemented in software, a computer-readable recording medium on which one or more programs (software modules) are recorded can be provided. The one or more programs recorded on the computer-readable recording medium are configured to be executable by one or more processors in an electronic device. The one or more programs include instructions for performing the methods according to the embodiments described in the claims or detailed description of this disclosure.

[0223] Those skilled in the art will understand that the exemplary embodiments described herein are not intended to be limiting. It should be understood that any two or more embodiments disclosed herein can be combined in any combination. Furthermore, other embodiments may be utilized, and other changes may be made without departing from the spirit and scope of the subject matter presented herein. It will be readily understood that various aspects of the invention disclosed herein, as generally described and illustrated in the accompanying drawings, can be arranged, substituted, combined, separated, and designed into a variety of different configurations, all of which are contemplated herein.

[0224] Those skilled in the art will understand that the various illustrative logic blocks, modules, circuits, and steps described in this application can be implemented as hardware, software, or a combination of both. To clearly illustrate this interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps are generally described above as sets of their functions. Whether such a set of functions is implemented as hardware or software depends on the specific application and the design constraints imposed on the system as a whole. Those skilled in the art may implement the described set of functions in different ways for each specific application, but such design decisions should not be construed as deviating from the scope of this application.

[0225] The various illustrative logic blocks, modules, and circuits described in this application may be implemented or performed by a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a combination of multiple microprocessors, a combination of one or more microprocessors cooperating with a DSP core, or any other such configuration.

[0226] The steps of the methods or algorithms described in this application can be implemented directly in hardware, in a software module executed by a processor, or in a combination thereof. The software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, or any other form of storage medium known in this art. Example storage media is coupled to a processor to enable the processor to read information from and write information to the storage medium. Alternatively, the storage medium can be integrated into the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. Alternatively, the processor and storage medium can reside as discrete components in the user terminal.

[0227] In one or more exemplary designs, the described functionality may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, each functionality may be stored or transmitted as one or more instructions or code on or through a computer-readable medium. Computer-readable media include computer storage media and communication media, the latter including any medium that facilitates the transfer of a computer program from one place to another. Storage media may be any available medium accessible by a general-purpose or special-purpose computer.

[0228] Any of the above variations can be used independently or in combination with at least one other variation. The flowcharts above illustrate example methods that can be implemented according to the principles of this disclosure, and various changes can be made to the methods shown in the flowcharts herein. For example, although shown as a series of steps, the individual steps in each figure can overlap, occur in parallel, occur in different orders, or occur multiple times. In another instance, steps may be omitted or replaced by other steps.

[0229] While this disclosure has been described with reference to exemplary embodiments, various changes and modifications may be suggested to those skilled in the art. This disclosure is intended to cover such changes and modifications that fall within the scope of the appended claims. Nothing described in this application should be construed as implying that any particular element, step, or function is an essential element that must be included within the scope of the claims. The scope of the patent is defined by the claims.

Claims

1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising: The random access process was not completed; In the event that the random access preamble is repeatedly transmitted and no contention-free random access resource is provided for the random access procedure, identify whether the preamble transmission counter is equal to a specific value. and If the preamble transmission counter is equal to the specific value and a set of random access resources associated with the higher message 1 repetition count is available, the set of random access resources is selected for the random access procedure.

2. The method according to claim 1, wherein, The specific value is equal to the maximum number of random access preambles sent with message 1 repeated plus 1.

3. The method according to claim 1, wherein, The specific value is equal to twice the maximum number of random access preambles sent with message 1 repeating plus 1.

4. The method according to claim 1, wherein, The identification includes identifying the expiration of the duration associated with the random access procedure, and The duration includes a contention resolution timer or a random access response window.

5. The method according to claim 1, wherein, The random access procedure is set to a 4-step random access procedure.

6. The method of claim 1, further comprising: In the Physical Random Access Channel (PRACH) timing set, the random access preamble is sent to the base station up to the higher message 1 repetition number of times.

7. The method according to claim 1, wherein, The random access resource set is associated with the next message 1 repetition count, which is higher than the current random access resource set.

8. A user equipment (UE) in a wireless communication system, the UE comprising: transceiver; as well as A controller, coupled to the transceiver and configured to: The random access process was not completed; In the event that the random access preamble is repeatedly transmitted and no contention-free random access resource is provided for the random access procedure, identify whether the preamble transmission counter is equal to a specific value. and If the preamble transmission counter is equal to the specific value and a set of random access resources associated with the higher message 1 repetition count is available, the set of random access resources is selected for the random access procedure.

9. The UE according to claim 8, wherein, The specific value is equal to the maximum number of random access preambles sent with message 1 repeated plus 1.

10. The UE according to claim 8, wherein, The specific value is equal to twice the maximum number of random access preambles sent with message 1 repeating plus 1.

11. The UE according to claim 8, wherein, The controller is also configured to recognize the expiration of a duration associated with the random access procedure, and The duration includes a race-resolver timer.

12. The UE according to claim 8, wherein, The controller is also configured to recognize the expiration of a duration associated with the random access procedure, and The duration includes the random access response window.

13. The UE according to claim 8, wherein, The random access procedure is set to a 4-step random access procedure.

14. The UE according to claim 8, wherein, The controller is also configured to: In the Physical Random Access Channel (PRACH) timing set, the random access preamble is sent to the base station up to the higher message 1 repetition number of times.

15. The UE according to claim 8, wherein, The random access resource set is associated with the next message 1 repetition count, which is higher than the current random access resource set.

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