L1 / L2 triggered mobility execution

Abstract

The present disclosure relates to a 5G communication system or a 6G communication system for supporting higher data rates beyond 4G communication systems such as Long Term Evolution (LTE). Methods and apparatus are provided for L1 / L2 triggered mobility execution in a wireless communication system. The method of the UE comprises: receiving information related to the suitability of (i) the LTM configuration and (ii) the LTM configuration for failure recovery performed from the LTM; determining whether applicability of an LTM configuration for recovery from a failure performed by the LTM is enabled; determining whether LTM execution is faulty; performing a cell selection operation based on the determination of the LTM execution failure; determining whether the cell selected in the cell selection operation is an LTM candidate cell; performing an LTM execution based on a determination that the cell is an LTM cell and a suitability of an LTM configuration for recovering from a failure of the LTM execution is enabled; and applying LTM configuration and sending a random access preamble.

Description

Technical Field

[0001] The present disclosure generally relates to wireless communication systems, and more particularly, the present disclosure relates to layer 1 / layer 2 (L1 / L2)-triggered mobility execution in wireless communication systems. Background Art

[0002] Considering the development of wireless communication from generation to generation, technologies mainly for human-targeted services such as voice calls, multimedia services, and data services have been developed. Following the commercialization of 5G (the 5th generation) communication systems, the number of connected devices is expected to grow exponentially. These will be increasingly connected to the communication network. Examples of connected things can include vehicles, robots, drones, household appliances, displays, smart sensors connected to various infrastructures, construction machinery, and factory equipment. Mobile devices are expected to evolve in various form factors such as augmented reality glasses, virtual reality headsets, and holographic devices. In order to provide various services in the 6G (the 6th generation) era by connecting hundreds of billions of devices and things, continuous efforts have been made to develop improved 6G communication systems. For these reasons, 6G communication systems are called ultra-5G systems.

[0003] The 6G communication system expected to be commercialized around 2030 will have a peak data rate of trillions (1,000 gigabits) per second and a radio latency of less than 100 μsec, and will thus be 50 times faster than 5G communication systems and have 1 / 10 of the radio latency of 5G communication systems.

[0004] To achieve such high data rates and ultra-low latencies, it has been considered to implement 6G communication systems in the terahertz band (e.g., 95 GHz to 3 THz band). Since path loss and atmospheric absorption in the terahertz band are expected to be more severe than those in the mmWave band introduced in 5G, technologies capable of ensuring signal transmission distance (i.e., coverage) will become more critical. As the main technology for ensuring coverage, it is necessary to develop radio frequency (RF) components, antennas, novel waveforms with better coverage than orthogonal frequency division multiplexing (OFDM), beamforming, and massive multiple input multiple output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, and multi-antenna transmission technologies such as massive antennas. In addition, new technologies for improving the coverage of terahertz band signals such as metasurface-based lenses and antennas, orbital angular momentum (OAM), and reconfigurable intelligent surfaces (RIS) have been under discussion.

[0005] In addition, to improve spectral efficiency and overall network performance, the following technologies have been developed for 6G communication systems: full-duplex technology that enables uplink and downlink transmissions to simultaneously use the same frequency resources; network technologies for integrally leveraging satellites, high-altitude platform stations (HAPS), etc.; improved network architectures for supporting mobile base stations, etc. and achieving optimized and automated network operations; conflict-avoidance dynamic spectrum sharing technology based on spectrum usage prediction; the use of artificial intelligence (AI) in wireless communication to enhance overall network operations by leveraging AI from the design phase for developing 6G and internalizing end-to-end AI support capabilities; and next-generation distributed computing technology to overcome the limitations of UE computing capabilities through reachable ultra-high-performance communication and computing resources on the network, such as mobile edge computing (MEC), cloud, etc. In addition, attempts to enhance connectivity between devices, optimize the network, promote the softwareization of network entities, and increase the openness of wireless communication are continuing by designing new protocols to be used in 6G communication systems, developing mechanisms for implementing hardware-based secure environments and secure use of data, and developing technologies for maintaining privacy.

[0006] Research and development of 6G communication systems in hyper-connectivity, including person-to-machine (P2M) and machine-to-machine (M2M), is expected to enable the next hyper-connectivity experience. Specifically, services such as true immersive extended reality (XR), high-fidelity mobile holograms, and digital replicas are expected to be provided through 6G communication systems. In addition, services such as remote surgery, industrial automation, and emergency response for security and reliability enhancement will be provided through 6G communication systems, enabling these technologies to be applied to various fields such as industry, healthcare, automotive, and household appliances. Summary of the Invention

[0007] Technical Problem

[0008] The present disclosure relates to a wireless communication system, and more particularly, to L1 / L2-triggered mobility execution in a wireless communication system.

[0009] Solution to the Problem

[0010] In one embodiment, a user equipment (UE) is provided in a wireless communication system. The UE includes a transceiver configured to receive information related to (i) an LTM configuration and (ii) the applicability of the LTM configuration for fault recovery from LTM execution. The UE further includes a processor operatively coupled to the transceiver, the processor being configured to: determine whether the applicability of the LTM configuration for fault recovery from LTM execution is enabled based on the information, determine whether LTM execution has failed, perform a cell selection operation based on the determination of LTM execution failure, determine whether the cell selected in the cell selection operation is an LTM candidate cell based on the LTM configuration, perform LTM execution to the cell based on the determination that the cell is an LTM candidate cell and the determination that the applicability of the LTM configuration for fault recovery from LTM execution is enabled, and apply the LTM configuration to the cell, wherein the transceiver is further configured to send a random access preamble to the cell for performing a random access procedure.

[0011] In another embodiment, a method for a UE in a wireless communication system is provided, the method comprising: receiving information related to (i) an LTM configuration and (ii) the applicability of the LTM configuration for fault recovery from LTM execution; determining whether the applicability of the LTM configuration for fault recovery from LTM execution is enabled based on the information; determining whether LTM execution has failed; performing a cell selection operation based on the determination of LTM execution failure; determining whether the cell selected in the cell selection operation is an LTM candidate cell based on the LTM configuration; performing LTM execution to the cell based on the determination that the cell is an LTM candidate cell and the determination that the applicability of the LTM configuration for fault recovery from LTM execution is enabled; applying the LTM configuration to the cell; and sending a random access preamble for performing a random access procedure to the cell.

[0012] In yet another embodiment, a base station (BS) is provided in a wireless communication system. The BS includes a processor configured to: generate information indicating whether the applicability of the LTM configuration for fault recovery from LTM execution is determined to be enabled; and a transceiver configured to send information related to (i) an LTM configuration and (ii) the applicability of the LTM configuration for fault recovery from LTM execution, wherein: it is determined whether LTM execution has failed, a cell selection operation is performed based on the determination of LTM execution failure, it is determined whether the cell selected in the cell selection operation is an LTM candidate cell based on the LTM configuration, LTM execution is performed to the cell based on the determination that the cell is an LTM candidate cell and the determination that the applicability of the LTM configuration for fault recovery from LTM execution is enabled, the LTM configuration for the cell is applied, and a random access preamble is sent to the cell for performing a random access procedure.

[0013] Other technical features may be apparent to those skilled in the art based on the following drawings, description, and claims.

[0014] Before proceeding with the following detailed description, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The term "coupled" and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with each other. The terms "send," "receive," and "communicate" and their derivatives cover both direct and indirect communication. The terms "include" and "comprise" and their derivatives mean including but not limited to. The term "or" is inclusive and means and / or. The phrase "associated with" and its derivatives mean including, being included within, interconnected with, containing, being contained within, connected to or coupled with, capable of communicating with, cooperating with, interlacing, juxtaposing, adjacent to, bound to or coupled to, having, having the attribute of, and having a relationship or being related to, etc. The term "controller" means any device, system, or part thereof that controls at least one operation. Such a controller can be implemented in hardware or in a combination of hardware and software and / or firmware. The functions associated with any particular controller can be centralized or distributed, whether locally or remotely. The phrase "at least one of" when used with a list of items means that different combinations of one or more of the listed items can be used and that possibly only one item from the list is required. 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 and B and C.

[0015] In addition, the various functions described below can be implemented or supported by one or more computer programs, each formed from computer-readable program code and embodied 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, related data, or portions thereof that are adapted to be implemented 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 that can be accessed by a computer, such as read-only memory (ROM), random access memory (RAM), hard disk drive, compact disc (CD), digital video disc (DVD), or any other type of memory. A "non-transitory" computer-readable medium excludes wired, wireless, optical, or other communication links that transmit transitory electrical or other signals. A non-transitory computer-readable medium 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 memory devices.

[0016] Throughout this patent document, definitions of certain words and phrases are provided. Those of ordinary skill in the art should understand that in many, if not most, instances, such definitions apply to both the prior and future use of the words and phrases so defined.

[0017] Advantageous Effects of the Invention

[0018] According to an embodiment of the present disclosure, a wireless data communication service can be effectively performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] To more fully understand the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts:

[0020] Figure 1 Shows an example of a wireless network according to an embodiment of the present disclosure;

[0021] Figure 2 Shows an example of a gNB according to an embodiment of the present disclosure;

[0022] Figure 3 Shows an example of a UE according to an embodiment of the present disclosure;

[0023] Figure 4 and Figure 5 Shows an example of a wireless transmit and receive path according to the present disclosure;

[0024] Figure 6 Shows a flowchart of UE behavior regarding processing an LTM execution timer according to an embodiment of the present disclosure;

[0025] Figure 7A Shows a flowchart of UE behavior when a UE receives one or more HO commands according to an embodiment of the present disclosure;

[0026] Figure 7B Shows a flowchart of UE behavior when a UE receives one or more HO commands according to an embodiment of the present disclosure; and

[0027] Figure 8 Shows a flowchart of a UE method for mobility execution triggered by L1 / L2 according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0028] The fifth generation (5G) or New Radio (NR) mobile communications has recently gathered increasing momentum with all the global technical activities from industry and academia on various candidate technologies. The candidate enablers of 5G / NR mobile communications include massive antenna technologies from traditional cellular bands to high frequencies to provide beamforming gain and support increased capacity, new waveforms (e.g., new radio access technologies (RATs)) to flexibly adapt to various services / applications with different requirements, new multiple access schemes to support massive connectivity, and so on.

[0029] As discussed below Figures 1 to 8 and the various embodiments for describing the principles of the present disclosure in this patent document are merely illustrative and should not be construed in any way as limiting the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0030] The following documents are incorporated by reference into the present disclosure as if fully set forth herein: 3GPP TR 38.811 v15.2.0, "Study on NR to support non-terrestrial networks"; 3GPP TR 38.821 v16.0.0, "Solutions for NR to support non-terrestrial networks (NTN)"; 3GPP TS 38.300 v17.2.0, "5G; NR; NR and NG-RAN Overall description; Stage-2"; 3GPP TS 38.331 v17.2.0, "5G; NR; Radio Resource Control (RRC); Protocol specification"; 3GPP TS 38.306 v17.2.0, "5G; NR; User Equipment (UE) radio access capabilities"; 3GPP, TS 38.304 v17.5.0, "5G; NR; User Equipment (UE) procedures in idle mode and in RRC Inactive state"; and 3GPP TS 38.321 v17.2.0, "5G; NR; Medium Access Control (MAC) protocol specification".

[0031] The following Figures 1 - 3 describes various embodiments implemented in a wireless communication system and using orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) communication techniques. Figures 1 - 3 The description does not imply a physical or architectural limitation on the manner in which different embodiments may be implemented. Different embodiments of the present disclosure may be implemented in any suitably arranged communication system.

[0032] Figure 1 shows an example wireless network according to an embodiment of the present disclosure. Figure 1The illustrated embodiments of the wireless network are for illustrative purposes only. Other embodiments of the wireless network 100 may be used without departing from the scope of the present disclosure.

[0033] As Figure 1 shown, the wireless network includes gNBs 101 (e.g., base stations, BSs), 102, and 103. gNB 101 communicates with gNBs 102 and 103. gNB 101 also communicates with at least one network 130 such as the Internet, a proprietary Internet Protocol (IP) network, or other data networks.

[0034] gNB 102 provides wireless broadband access to network 130 for a first plurality of UEs within coverage area 120 of gNB 102. 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 (E); UE 113, which may be located in a WiFi hotspot (HS); UE 114, which may be located in a first residence (R); UE 115, which may be located in a second residence (R); and UE 116, which may be a mobile device (M) such as a cellular phone, a wireless laptop computer, a wireless PDA, etc. gNB 103 provides wireless broadband access to network 130 for a second plurality of UEs within coverage area 125 of gNB 103. 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), Long Term Evolution - Advanced (LTE - A), WiMAX, WiFi, or other wireless communication technologies.

[0035] Depending on the network type, the term "base station" or "BS" can refer to any component (or collection of components) configured to provide wireless access to a network, such as a transmission point (TP), a transmit-receive point (TRP), an enhanced base station (eNodeB or eNB), a 5G / NR base station (gNB), a macrocell, a femtocell, a Wi-Fi access point (AP), or other wireless-enabled devices. The base station can provide wireless access according to one or more wireless communication protocols (e.g., 5G / NR 3GPP NR, Long-Term Evolution (LTE), LTE-Advanced (LTE-A), High-Speed Packet Access (HSPA), Wi-Fi 802.11 a / b / g / n / ac, etc.). For convenience, the terms "BS" and "TRP" can be used interchangeably in this patent document to refer to the network infrastructure components that provide wireless access to remote terminals. Additionally, 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 the remote wireless devices that wirelessly access the BS, whether the UE is a mobile device (such as a mobile phone or smartphone) or a device that is typically considered fixed (such as a desktop computer or vending machine).

[0036] The dashed lines illustrate the approximate extent of coverage areas 120 and 125, which are shown as approximately circular for purposes of illustration and explanation only. It should be clearly understood that the coverage areas associated with a gNB, such as coverage areas 120 and 125, can have other shapes, including irregular shapes, depending on the configuration of the gNB and the variations in the radio environment associated with natural and man-made obstacles.

[0037] As discussed in more detail below, the wireless network 100 can have communication facilitated via one or more communication satellites 104 that can be in Earth orbit. The communication satellites 104 can communicate directly with BS 102 and BS 103 to provide network access, for example, in cases where BS 102 and BS 103 are remotely located or otherwise require network access connections beyond what traditional fronthaul and / or backhaul connections can facilitate. Various UEs (e.g., as depicted by UE 116) can be able to communicate directly with and / or be positioned relative to the communication satellites 104, for example, to receive location information or coordinates.

[0038] NTN refers to a network or network segment that uses RF resources on a communication satellite (or unmanned aerial vehicle system platform) (e.g., communication satellite 104). Given the ability to provide wide coverage and reliable services, NTN is envisioned to ensure ubiquitous service availability and continuity. For example, NTN can support communication services in unserved areas not covered by traditional terrestrial networks, in underserved areas experiencing limited communication services, for devices and passengers on mobile platforms, and for future railway / maritime / aviation communications, etc.

[0039] As described in more detail below, one or more of UEs 111 - 116 include circuitry, programming, or a combination thereof for performing mobility triggered by L1 / L2 in a wireless communication system. In certain embodiments, one or more of gNBs 101 - 103 include circuitry, programming, or a combination thereof to support mobility execution triggered by L1 / L2 in a wireless communication system.

[0040] Although Figure 1 An example of a wireless network is shown, various changes can be made to Figure 1 it. For example, a wireless network can include any number of gNBs and any number of UEs arranged in any suitable manner. Additionally, gNB 101 can communicate directly with any number of UEs and provide these UEs with wireless broadband access to network 130. Similarly, each of gNBs 102 - 103 can communicate directly with network 130 and provide UEs with direct wireless broadband access to network 130. Further, gNBs 101, 102, and / or 103 can provide access to other or additional external networks (such as an external telephone network or other types of data networks).

[0041] Figure 2 An example gNB 102 according to an embodiment of the present disclosure is shown. Figure 2 The embodiment of gNB 102 shown in Figure 1 is for illustration only, and gNBs 101 and 103 of Figure 2 can have the same or similar configurations. However, gNBs have a wide variety of configurations, and

[0042] As Figure 2 shown, gNB 102 includes a plurality of antennas 205a - 205n, a plurality of transceivers 210a - 210n, a controller / processor 225, a memory 230, and a backhaul or network interface 235.

[0043] Transceivers 210a - 210n receive incoming RF signals from antennas 205a - 205n, such as signals transmitted by UEs in network 100. The transceivers 210a - 210n down - convert the incoming RF signals to generate IF or baseband signals. The IF or baseband signals are processed by receive (RX) processing circuitry in the transceivers 210a - 210n and / or the controller / processor 225, and the RX processing circuitry generates a processed baseband signal by filtering, decoding, and / or digitizing the baseband or IF signal. The controller / processor 225 may further process the baseband signal.

[0044] Transmit (TX) processing circuitry in the transceivers 210a - 210n and / or the controller / processor 225 receives analog or digital data (such as voice data, web data, email, or interactive video game data) from the controller / processor 225. The TX processing circuitry encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The transceivers 210a - 210n up - convert the baseband or IF signal to an RF signal transmitted via antennas 205a - 205n.

[0045] The controller / processor 225 may include one or more processors or other processing devices that control the overall operation of the gNB 102. For example, the controller / processor 225 may control the transceivers 210a - 210n to receive UL channel signals and transmit DL channel signals according to well - known principles. The controller / processor 225 may also support additional functions, such as more advanced wireless communication functions. For example, the controller / processor 225 may support beamforming or directional routing operations, where outgoing / incoming signals from / to multiple antennas 205a - 205n are weighted differently to effectively direct the outgoing signal in a desired direction. The controller / processor 225 may support any of a variety of other functions in the gNB 102.

[0046] The controller / processor 225 is also capable of executing programs and other processes residing in the memory 230, such as the OS. The controller / processor 225 may move data into or out of the memory 230 as needed for the execution of processes. The controller / processor 225 is also capable of executing programs and other processes residing in the memory 230, such as processes for supporting mobility execution for L1 / L2 triggers in a wireless communication system.

[0047] The controller / processor 225 is also coupled to a backhaul or network interface 235. The backhaul or network interface 235 allows the gNB 102 to communicate with other devices or systems via a backhaul connection or via the network. The interface 235 may support communication via any suitable wired or wireless connection. For example, when the gNB 102 is implemented as part of a cellular communication system (such as a cellular communication system supporting 5G / NR, LTE, or LTE-A), the interface 235 may 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, the interface 235 may 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. The interface 235 includes any suitable structure that supports communication via a wired or wireless connection, such as Ethernet or a transceiver.

[0048] The memory 230 is coupled to the controller / processor 225. A portion of the memory 230 may include RAM, and another portion of the memory 230 may include flash memory or other ROM.

[0049] Although Figure 2 an example of the gNB 102 is shown, various changes may be made to Figure 2 it. For example, the gNB 102 may include any number of Figure 2 each of the components shown in Figure 2 Furthermore, the various components in

[0050] Figure 3 An example UE 116 according to an embodiment of the present disclosure is shown. Figure 3 The embodiment of the UE 116 shown in Figure 1 is for illustration only, and the UEs 111 - 115 Figure 3 may have the same or similar configurations. However, UEs have a wide variety of configurations, and

[0051] As Figure 3 shown, the UE 116 includes an antenna 305, a transceiver 310, and a microphone 320. The UE 116 also includes a speaker 330, a processor 340, an input / output (I / O) interface (IF) 345, an input 350, a display 355, and a memory 360. The memory 360 includes an operating system (OS) 361 and one or more applications 362.

[0052] The transceiver 310 receives an incoming RF signal transmitted by the gNB of the network 100 from the antenna 305. The transceiver 310 down-converts the incoming RF signal to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is processed by RX processing circuitry in the transceiver 310 and / or the processor 340, and the RX processing circuitry generates a processed baseband signal by filtering, decoding, and / or digitizing the baseband or IF signal. The RX processing circuitry sends the processed baseband signal to the speaker 330 (such as for voice data) or is processed by the processor 340 (such as for web browsing data).

[0053] TX processing circuitry in the transceiver 310 and / or the processor 340 receives analog or digital voice data from the microphone 320, or other outgoing baseband data (such as web data, email, or interactive video game data) from the processor 340. The TX processing circuitry encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The transceiver 310 up-converts the baseband or IF signal to an RF signal transmitted via the antenna 305.

[0054] The processor 340 may include one or more processors or other processing devices and executes the OS 361 stored in the memory 360 to control the overall operation of the UE 116. For example, the processor 340 may control the transceiver 310 to receive DL channel signals and transmit UL channel signals according to well-known principles. In some embodiments, the processor 340 includes at least one microprocessor or microcontroller.

[0055] The processor 340 is also capable of executing other processes and programs residing in the memory 360, such as processes for mobility execution triggered by L1 / L2 in a wireless communication system. The processor 340 may move data into or out of the memory 360 as needed for executing processes. In some embodiments, the processor 340 is configured to execute the application 362 based on the OS 361 or in response to a signal received from the gNB or the operator. The processor 340 is also coupled to the I / O interface 345, and the I / O interface 345 provides the UE 116 with the ability to connect to other devices (such as laptop computers and handheld computers). The I / O interface 345 is a communication path between these accessories and the processor 340.

[0056] The processor 340 is also coupled to the input 350 and the display 355. The input 350 includes, for example, a touch screen, a keyboard, etc. The operator of the UE 116 can use the input 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 presenting text and / or at least limited graphics such as from a website.

[0057] Memory 360 is coupled to processor 340. A portion of memory 360 may include random access memory (RAM), and another portion of memory 360 may include flash memory or other read-only memory (ROM).

[0058] Although Figure 3 an example of UE 116 is shown, various changes may be made Figure 3 thereto. For example, various components in Figure 3 may be combined, further subdivided, or omitted, and additional components may be added according to specific requirements. As a specific example, processor 340 may 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 may include any number of transceivers and signal processing chains, and may be connected to any number of antennas. Furthermore, although Figure 3 UE 116 is shown configured as a mobile phone or a smart phone, the UE may be configured to operate as other types of mobile or fixed devices.

[0059] Figure 4 and Figure 5 show example wireless transmit and receive paths in accordance with the present disclosure. In the following description, transmit path 400 may be described as being implemented in a gNB (such as gNB 102), while receive path 500 may be described as being implemented in a UE (such as UE 116). However, it will be understood that receive path 500 may be implemented in a gNB, and transmit path 400 may be implemented in a UE. In some embodiments, receive path 500 is configured to support L1 / L2-triggered mobility execution in a wireless communication system as described in embodiments of the present disclosure.

[0060] As Figure 4 shown, transmit path 400 includes a channel coding and modulation block 405, a serial-to-parallel (S-to-P) block 410, an inverse fast Fourier transform (IFFT) block 415 of size N, a parallel-to-serial (P-to-S) block 420, a cyclic prefix addition block 425, and an upconverter (UC) 430. As Figure 5 shown, receive path 500 includes a downconverter (DC) 555, a cyclic prefix removal block 560, a serial-to-parallel (S-to-P) block 565, a fast Fourier transform (FFT) block 570 of size N, a parallel-to-serial (P-to-S) block 575, and a channel decoding and demodulation block 580.

[0061] As Figure 4As shown, the channel coding and modulation block 405 receives a set of information bits, applies coding (such as low-density parity-check (LDPC) coding), and modulates the input bits (such as using quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM)) to generate a sequence of frequency-domain modulated symbols.

[0062] The serial-to-parallel block 410 converts (e.g., demultiplexes) the serially 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. The IFFT block 415 of size N performs an IFFT operation on the N parallel symbol streams to generate a time-domain output signal. The parallel-to-serial block 420 converts (such as multiplexes) the parallel time-domain output symbols from the IFFT block 415 of size N to generate a serial time-domain signal. The cyclic prefix addition block 425 inserts a cyclic prefix into the time-domain signal. The upconverter 430 modulates (such as upconverts) the output of the cyclic prefix addition block 425 to an RF frequency for transmission via the wireless channel. The signal may also be filtered at baseband before being converted to the RF frequency.

[0063] The RF signal transmitted from gNB 102 arrives at UE 116 after passing through the wireless channel, and operations opposite to those at gNB 102 are performed at UE 116.

[0064] As Figure 5 shown, the downconverter 555 downconverts the received signal to a baseband frequency, and the cyclic prefix removal block 560 removes the cyclic prefix to generate a serial time-domain baseband signal. The serial-to-parallel block 565 converts the time-domain baseband signal to a parallel time-domain signal. The FFT block 570 of size N performs an FFT algorithm to generate N parallel frequency-domain signals. The parallel-to-serial block 575 converts the parallel frequency-domain signals to a sequence of modulated data symbols. The channel decoding and demodulation block 580 demodulates and decodes the modulated symbols to recover the original input data stream.

[0065] Each of gNBs 101-103 can implement the transmission path 400 as Figure 4 shown, which is similar to transmitting to UEs 111-116 in the downlink, and can implement the reception path 500 as Figure 5 shown, which is similar to receiving from UEs 111-116 in the uplink. Similarly, each of UEs 111-116 can implement the transmission path 400 for transmitting to gNBs 101-103 in the uplink, and can implement the reception path 500 for receiving from gNBs 101-103 in the downlink.

[0066] Figure 4 and Figure 5Each component in can be implemented using only hardware or using a combination of hardware and software / firmware. As a specific example, Figure 4 and Figure 5 at least some of the components in can be implemented in software, while other components can be implemented by configurable hardware or a mixture of software and configurable hardware. For example, the FFT block 570 and the IFFT block 515 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 only by way of illustration and should not be construed as limiting the scope of the present disclosure. Other types of transforms can be used, such as the discrete Fourier transform (DFT) and the inverse discrete Fourier transform (IDFT) functions. It can be understood that for the DFT and IDFT functions, the value of the variable N can be any integer (e.g., 1, 2, 3, 4, etc.), while for the FFT and IFFT functions, the value of the variable N can be any integer that is a power of two (e.g., 1, 2, 4, 8, 16, etc.).

[0068] Although Figure 4 and Figure 5 show examples of wireless transmit and receive paths, various changes can be made to Figure 4 and Figure 5 . For example, various components in Figure 4 and Figure 5 can be combined, further subdivided, or omitted, and additional components can be added according to specific needs. Furthermore, Figure 4 and Figure 5 are intended to show 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] 3GPP has developed technical specifications and standards to define a new 5G radio access technology called 5G NR. Mobility handling is a key aspect in any mobile communication system including 5G systems. For a UE in the connected mode, mobility is controlled by the network with the assistance of the UE to maintain good connection quality. Based on the measurements of the radio link quality of the serving cell and neighboring cells reported by the UE, the network can switch the UE to a neighboring cell that can provide better radio conditions when the UE experiences a degraded connection to the serving cell. In Release 15 NR, the basic mechanisms and procedures for network-controlled mobility in the connected mode were developed. In Release 16 NR, enhancements to network-controlled mobility in the connected mode were introduced to mitigate connection interruptions during the handover process. Specifically, two enhanced handover mechanisms were developed, called conditional handover (CHO) and dual active protocol stack (DAPS).

[0070] For mobility in the connected mode, handovers are initiated by the network based on L3 measurements via higher layer signaling (e.g., RRC messages). However, this process involves more latency, signaling overhead, and interruption time, which can be a key issue in some scenarios with frequent handovers (e.g., high-speed vehicles and UEs in FR2 deployments). It is necessary to reduce the overhead and / or latency and interruption time during the handover process. This gives rise to the need for L1 / L2 (Layer 1 / Layer 2) triggered mobility (LTM), through which handovers can be triggered based on L1 measurements via L1 / L2 signaling. More specifically, LTM refers to a mobility mechanism in which a UE switches from a source cell to a target cell using beam switching triggered by L1 / L2 signaling, where the beam switching decision is based on L1 measurements of the beams between neighboring cells.

[0071] When LTM is initiated, it is desirable to specify how the UE performs LTM and how the UE handles the coexistence of L3 mobility, CHO, and LTM.

[0072] In the present disclosure, how the UE performs LTM is provided while considering L3 mobility and CHO. Specifically, the UE behavior regarding timers for LTM execution and the UE behavior for handling the coexistence of different HO mechanisms and LTM failure recovery are specified.

[0073] The UE performs LTM upon receiving an LTM MAC CE. To monitor the execution of LTM to the target cell, a timer with a duration parameter, i.e., the LTM execution timer, can be configured in the RRC message (e.g., RRCReconfiguration) for LTM configuration.

[0074] Figure 6 A flowchart of a UE method 600 for handling an LTM execution timer according to an embodiment of the present disclosure is shown. The UE method 600 can be executed by a UE (e.g., 111 - 116 as Figure 1 shown). Figure 6 The embodiments of the UE method 600 shown in Figure 6 are for illustrative purposes only. One or more of the components shown in

[0075] Figure 6An embodiment showing UE behavior regarding processing of the LTM execution timer is presented. At step 605, the UE receives the duration parameter of the LTM execution timer in an RRC message (e.g., RRCReconfiguration) for LTM configuration. In one example, each candidate cell is configured with a duration parameter, i.e., one timer duration is associated with one candidate cell ID. In another example, each candidate cell configuration is configured with a duration parameter, i.e., one timer duration is associated with one candidate cell configuration ID. In one example, the timer can be configured with different durations for LTM execution with a random access procedure and for LTM execution with a RACH-less operation respectively.

[0076] At step 610, the UE starts the LTM execution timer when receiving an LTM command (e.g., MAC CE) that triggers the execution of LTM. In one example, the LTM execution timer is maintained at the MAC layer. In another example, the LTM execution timer is maintained at the RRC layer. In this case, the MAC layer sends an indication to the RRC layer to start the LTM execution timer.

[0077] At step 615, the UE restarts the LTM execution timer (if running) when receiving a new or prioritized LTM command (e.g., MAC CE).

[0078] At step 620, when receiving a new or prioritized L3 HO command, or when successfully completing the random access procedure of the target cell of LTM, or when successfully receiving a PDCCH transmission addressed to the C-RNTI from the target cell in the case of RACH-less LTM, or when successfully receiving an acknowledgement (e.g., in a MAC CE or DCI or RRC message) from the target cell in the case of RACH-less LTM, the UE stops the LTM execution timer (if running).

[0079] At step 625, the UE declares an LTM execution failure when the LTM execution timer expires, and performs RRC reconstruction or LTM failure recovery.

[0080] In one embodiment of LTM fault recovery, the UE may be configured to attempt to recover by using the stored configuration of LTM candidate cells. In one example, the UE performs cell (re)selection during an LTM fault. If configured to recover via an LTM candidate cell and if the selected cell is one of the LTM candidate cells, the UE applies the stored LTM configuration to the selected cell and the UE performs a random access procedure for the cell, or if the UE has obtained UL synchronization with the cell, the UE performs a RACH-free handover to the cell. For cell (re)selection, the UE may prioritize LTM candidate cells (i.e., select a suitable cell from the LTM candidate cells). In another example, the UE may prioritize LTM candidate cells in which the UE has obtained UL synchronization during cell reselection (i.e., select a suitable cell from the LTM candidate cells).

[0081] In one example, the UE may prioritize those LTM candidate cells for which L1 measurement results (e.g., L1-RSRP) are available or better than the configured threshold in cell reselection (i.e., select a suitable cell from those LTM candidate cells). In yet another example, the UE may select the cell with the best L1 measurement result (e.g., L1-RSRP) among the prioritized cells. When performing cell (re)selection during an LTM fault, if multiple cells are selected in the cell (re)selection, the UE may select one cell until the UE achieves; or the UE may select the one for which L1 measurement results (e.g., L1-RSRP) for LTM are available and / or the best; or the UE may prioritize the cells in which the UE has obtained UL synchronization for LTM, or the cells configured as candidate cells for LTM.

[0082] In one embodiment, in the case of an LTM fault, the UE may retain other HO commands received before or during HO execution, which may be L3 HO commands or LTM commands, but not execute them. In one example, the UE may be configured via RRC signaling (e.g., RRCReconfiguration) to achieve retention of HO commands. If predefined or enabled via configuration, the UE may retain HO commands by storing the associated HO execution information (e.g., target cell ID, target cell configuration, cell / beam handover related information) in one or more UE variables.

[0083] When there is an LTM failure at step 625, the UE can then execute one of the reserved HO commands (e.g., an L3 HO command or an LTM command) according to the stored HO execution information. If multiple HO commands (e.g., an L3 HO command or an LTM command) are reserved, the UE can choose to execute one of the reserved HO commands until the UE achieves; and / or the UE can choose to execute the LTM command; and / or the UE can choose to execute one with a target cell that has obtained UL synchronization; and / or the UE can choose to execute one with a target cell whose L1 measurement result (e.g., L1-RSRP) is the best or better than the configured threshold. If LTM is successfully completed at step 620, i.e., there is no LTM failure, the UE releases the reserved HO commands after LTM completion.

[0084] In one embodiment, if the UE receives a second HO command (e.g., an L3 HO command or an LTM command) before starting the timer for executing the first HO command (e.g., the T304 timer for the L3 HO command or the LTM execution timer for the LTM command) or before executing the first HO command, the UE executes the second HO command, starts the corresponding timer, and ignores / reserves the first HO command.

[0085] In another embodiment, if the UE receives a second HO command (e.g., an L3 HO command or an LTM command) before starting the timer for executing the first HO command (e.g., the T304 timer for the L3 HO command or the LTM execution timer for the LTM command) or before executing the first HO command, the UE executes the first HO command, starts the corresponding timer, and ignores / reserves the second HO command.

[0086] In yet another embodiment, if the UE receives a second HO command (e.g., an L3 HO command or an LTM command) before starting the timer for executing the first HO command (e.g., the T304 timer for the L3 HO command or the LTM execution timer for the LTM command) or before executing the first HO command, the UE executes the prioritized HO command, starts the corresponding timer, and ignores / reserves the other HO command. In one instance, the LTM command is always prioritized. In another example, the L3 HO command is always prioritized. In an alternative example, the prioritization between LTM and L3 HO is preconfigured by an RRC message (e.g., RRCReconfiguration). In another example, the first HO command or the second HO command is prioritized using an indication in the corresponding HO command.

[0087] In one embodiment, if the UE receives a second HO command (e.g., an L3 HO command or an LTM command) while the timer for executing the first HO command (e.g., the T304 timer for the L3 HO command or the LTM execution timer for the LTM command) is running and before starting to synchronize to the target cell for the first HO command, the UE ignores / keeps the second HO command and continues to execute the first HO command.

[0088] In another embodiment, if the UE receives a second HO command (e.g., an L3 HO command or an LTM command) while the timer for executing the first HO command (e.g., the T304 timer for the L3 HO command or the LTM execution timer for the LTM command) is running and before starting to synchronize to the target cell for the first HO command, the UE stops the currently running timer, starts / restarts the timer for the second HO command, and executes the second HO command.

[0089] In yet another embodiment, if the UE receives a second HO command (e.g., an L3 HO command or an LTM command) while the timer for executing the first HO command (e.g., the T304 timer for the L3 HO command or the LTM execution timer for the LTM command) is running and before starting to synchronize to the target cell for the first HO command, then if the prioritization between L3 HO and LTM is predefined / configured or if the priority of one of the HO commands in the HO command is indicated, the UE executes the prioritized HO command. In one example, the prioritization between L3 HO and LTM can be configured by an RRC message (e.g., RRCReconfiguration). In another example, the priority of one of the HO commands can be indicated in the HO command (e.g., an L3 HO command or an LTM command). If the first HO command is prioritized, the UE ignores / keeps the second HO command and continues to execute the first HO command. If the second HO command is prioritized, the UE stops the currently running timer, starts / restarts the timer for the second HO command, and executes the second HO command.

[0090] In one embodiment, in the case where the UE needs to stop the currently running T304 timer in the RRC layer for the L3 HO execution command and start / restart the LTM execution timer in the MAC layer for the LTM command, after receiving the LTM command and before the LTM execution timer starts, the MAC layer sends an indication to the RRC layer to stop the execution of L3 HO and the currently running T304 timer. In the case where the UE needs to stop the currently running LTM execution timer in the MAC layer for the LTM execution command and start / restart the T304 timer in the RRC layer for the L3 HO command, after receiving the L3 HO command and before the T304 timer starts, the RRC layer sends an indication to the MAC layer to stop the execution of LTM and the currently running LTM execution timer.

[0091] In one embodiment, in the case where the UE receives the conditional configuration of CHO and starts to evaluate the CHO execution condition (i.e., the triggering event), before any CHO execution is satisfied, when receiving the LTM command, the UE performs LTM to switch to the target cell regardless of any previously received CHO configuration and evaluation.

[0092] In another embodiment, in the case where the UE successfully completes the cell handover to the target cell through the LTM operation, the UE releases the stored CHO configuration (if any) when the LTM is completed. In an alternative embodiment, in the case where the UE successfully completes the cell handover to the target cell through the LTM operation, the UE retains the stored CHO configuration (if any) when the LTM is completed. In one example, the UE may retain the CHO configurations of all candidate cells if predefined or configured by RRC or indicated in the MAC CE. In another example, the UE may retain the CHO configurations of certain candidate cells. Which candidate cells to retain the CHO configurations for may be indicated in the RRC message (e.g., RRCReconfiguration) containing the CHO configuration and / or the LTM configuration, or may be indicated in the LTM command (e.g., MAC CE).

[0093] Figure 7A A flowchart of a UE method 700 when the UE receives one or more HO commands according to an embodiment of the present disclosure is shown. The UE method 700 may be executed by a UE (e.g., such as Figure 1 shown in 111 - 116). Figure 7A The embodiments of the UE method 700 shown in Figure 7A are for illustration only. One or more components shown in

[0094] Figure 7B shows a flowchart of UE method 790 when a UE receives one or more HO commands according to an embodiment of the present disclosure. UE method 790 may be performed by a UE (e.g., 111-116 as shown Figure 1 ). Figure 7B The embodiment of UE method 790 shown in Figure 7B is for illustration only. One or more components shown in

[0095] may be implemented in a dedicated circuit configured to perform the functions, or one or more components may be implemented by one or more processors executing instructions to perform the functions. Figure 7A As shown Figure 7A step 740 in Figure 7B is connected to step 745 in

[0096] Figure 7A and Figure 7B shows an embodiment of UE behavior when one or more HO commands (L3 HO commands and L1 / L2 HO commands, e.g., LTM commands) are received.

[0097] At step 705, the UE may receive one or more HO commands including at least one LTM command. The HO commands may be L1 / L2 HO commands (e.g., LTM commands) and L3 HO commands received simultaneously or sequentially in the PDCCH and / or PDSCH.

[0098] At step 710, if instructed / configured to retain the received HO commands, the UE may retain the HO commands and store the information contained in the HO commands in UE variables. Alternatively, for step 710, the UE may retain all HO commands received from the source cell before disconnecting from the source cell and / or before starting to synchronize to the target cell.

[0099] To enable reservation / storage of HO commands, the HO commands may include an indication. For example, the L3 HO command may include a field in the RRCReconfiguration message to indicate that the HO command needs to be retained by the UE; the LTM command may include a field in the MAC CE to indicate that the LTM command needs to be retained by the UE.

[0100] UE variables may be used to retain / store / cumulate the information contained in HO commands. The UE variables may include a list of received HO commands, and each entry in the list includes the information contained in the corresponding HO command. If the HO command is indicated to be retained / stored, the UE stores the HO command and the associated information in the variable.

[0101] The information in each HO command to be stored may include, for example, the target cell ID, the target cell configuration, the associated execution timer parameters (e.g., timer duration), cell / beam handover related information (e.g., TCI state ID), etc. The information in each HO command may also include the execution priority. In one example, the HO command may include a priority level indication. For example, a smaller priority level number indicates a higher priority, i.e., priority level 1 indicates a higher priority than priority level 2. The UE may store the priority level associated with the HO command.

[0102] In another example, the HO command may include a prioritization status, and the enabled prioritization status indicates that the execution of this HO command has priority over other HO commands without the enabled prioritization status. When receiving a new HO command with the prioritization status enabled, the UE may update the prioritization status of all stored HO commands. The UE may prioritize the most recently received HO command with the prioritization status enabled, i.e., the prioritization of the most recently received HO command with the prioritization status enabled has priority over the prioritization of the previously received HO command with the prioritization status enabled.

[0103] In step 715, the UE determines the HO command to be executed from all received HO commands according to predefined rules and / or pre - configurations and / or indications.

[0104] In one example, when receiving the first HO command from the source cell, the UE determines to execute the received first HO command and ignores other HO commands received later during the execution of the first HO command.

[0105] In another example, when receiving the first HO command from the source cell, the UE determines to execute the received first HO command. For any HO command received after the first HO command and before starting the timer for executing the first HO command or before executing the first HO command or before disconnecting from the source cell or before starting to synchronize to the target cell, the UE retains the HO command and stores the associated information if the HO command is indicated to be retained.

[0106] In one example, after receiving the first HO command from the source cell, if the UE receives other HO commands before starting the timer for executing the first HO command or before executing the first HO command or before disconnecting from the source cell or before starting to synchronize to the target cell, the UE determines to execute the most recently received HO command. The UE may ignore the first HO command and any other HO commands; alternatively, if indicated to retain, the UE may retain any HO command, including the first HO command.

[0107] In yet another embodiment, after receiving a first HO command from a source cell, if the UE receives other HO commands before starting a timer for executing the first HO command, or before executing the first HO command, or before disconnecting from the source cell, or before starting to synchronize to a target cell, the UE determines to execute the prioritized HO command among all received HO commands. The UE may ignore the first HO command and any other HO commands; alternatively, if instructed to retain, the UE may retain any HO command, including the first HO command.

[0108] To determine the prioritized HO command, for one example, if the priority is indicated in the HO command, the UE determines to execute the HO command with the highest priority. In another example, if the prioritization status is enabled in the HO command, the UE determines to execute the HO command with the prioritization status enabled. The UE may prioritize the most recently received HO command with the prioritization status enabled, i.e., the prioritization of the most recently received HO command with the prioritization status enabled takes precedence over the prioritization of the previously received HO command with the prioritization status enabled.

[0109] In yet another example of determining the prioritized HO command, the UE follows a predefined rule. Examples include one or more of the following: (1) L1 / L2 HO commands (e.g., LTM commands) take precedence over L3 HO commands; (2) L3 HO commands take precedence over L1 / L2 HO commands (e.g., LTM commands); and / or (3) among multiple L1 / L2 HO commands (e.g., LTM commands), prioritize the HO command of the target cell that meets one or more conditions. One condition may be that the UE has synchronized to the corresponding target cell. Another condition may be that a timer for maintaining UL synchronization with the target cell (e.g., TimeAlignmentTimer) is running, and / or running with the longest remaining duration. Another condition may be that the L1 measurement result (e.g., L1-RSRP value) of the target cell is the best among all target cells, and / or better than a threshold.

[0110] In steps 720 and 725, the UE checks whether an HO command is being executed (i.e., the HO execution timer is running) and whether it is determined to execute a new HO command.

[0111] If the UE determines to execute a new HO command, the UE stops the current HO execution timer (if there is a timer running) (i.e., step 730), and starts / restarts the timer that supervises the execution of the new HO command, and executes the HO by performing a random access to the target cell or a RACH-less HO (i.e., step 735). Otherwise, (i.e., if there is a timer running for HO execution and the UE determines not to execute a new HO command), the UE continues the current HO execution and maintains the current HO execution timer.

[0112] In steps 730 and 735, in the case where the current running timer that supervises HO execution is controlled by the RRC layer and the UE determines to execute a new L1 / L2 HO command (e.g., LTM command) (for which a timer controlled by the MAC layer will be started), the UE receives an indication of L1 / L2 HO execution (e.g., LTM execution) from the lower layer (e.g., MAC layer), and stops the current timer in the RRC layer. In another example, if the current running timer that supervises HO execution is controlled by the MAC layer, and the UE determines to execute a new L3 HO command, for which a timer controlled by the RRC layer will be started, the UE receives an indication of L3 HO execution from the RRC layer, and stops the current timer in the MAC layer. In one example, if the UE determines to execute a new L1 / L2 HO command (e.g., LTM command) for which a timer controlled by the RRC layer is to be started, the UE stops the current running timer (if any) in the RRC layer, and starts a new RRC timer for supervising L1 / L2 HO execution (e.g., LTM execution). And the RRC layer and the lower layer (e.g., MAC layer and / or PHY layer) exchange information on the start / stop / expiry of the RRC timer.

[0113] In step 745, if no new HO command is received before disconnecting from the source cell or before starting to synchronize to the target cell, the UE continues the current HO execution, stops the associated timer upon successful completion of the HO, and sends a successful HO confirmation to the new serving cell (i.e., the target cell of the HO). Upon successful completion of the HO, the UE may release the reserved HO command (if any) and remove the associated information from the stored variables.

[0114] When the HO execution timer expires, the UE declares an HO failure (i.e., step 750), and performs RRC reconstruction and / or HO failure recovery (e.g., LTM failure recovery) and / or subsequently performs the reserved HO command, i.e., step 755. The UE may determine to perform the reserved HO command as described above in step 715. Upon successful HO failure recovery and / or upon successful connection (re)establishment and / or upon successful execution of a subsequent HO command, the UE may release the reserved HO command (if any) and remove the relevant information from the stored variables.

[0115] Figure 8 FIG. shows a flowchart of a UE method 800 for L1 / L2-triggered mobility execution according to an embodiment of the present disclosure. The UE method 800 may be performed by a UE (e.g., such as Figure 1 shown in 111-116). Figure 8 The embodiment of the UE method 800 shown in Figure 8 is for illustration only.

[0116] As Figure 8 shown, the UE method 800 begins at step 802. In step 802, the UE receives information related to (i) LTM configuration and (ii) the applicability of the LTM configuration for failure recovery from LTM execution.

[0117] In step 804, the UE determines whether the applicability of the LTM configuration for failure recovery from LTM execution is enabled based on the information.

[0118] In step 806, the UE determines whether the LTM execution has failed.

[0119] In step 808, the UE performs a cell selection operation based on the determination of LTM execution failure.

[0120] In step 810, the UE determines whether the cell selected in the cell selection operation is an LTM candidate cell based on the LTM configuration.

[0121] In step 812, the UE performs LTM execution to the cell based on the determination that the cell is an LTM candidate cell and the determination that the applicability of the LTM configuration for failure recovery from LTM execution is enabled.

[0122] In step 814, the UE applies the LTM configuration to the cell.

[0123] In step 816, the UE sends a random access preamble for performing a random access procedure to the cell.

[0124] In one embodiment, the UE performs LTM execution to a target cell when (i) a command associated with LTM execution is received and (ii) the CHO execution condition for the target cell is evaluated.

[0125] In one embodiment, the UE receives priority configuration information for mobility operations indicating LTM operations, HO operations, or CHO operations, where the priority configuration information includes an indication of which mobility operation among the mobility operations is prioritized.

[0126] In one embodiment, the UE receives priority configuration information for mobility operations indicating LTM operations, HO operations, and CHO operations, where the priority configuration information includes an indicator indicating the priority level of each mobility operation.

[0127] In one embodiment, the UE receives (i) a plurality of mobility commands and (ii) priority configuration information; identifies the prioritized mobility command from the plurality of mobility commands based on the priority configuration information; and executes the mobility command.

[0128] In one embodiment, the UE receives at least one mobility command; and prioritizes the at least one mobility command based on a condition associated with the target cell, where the condition is determined based on the TA of the target cell or the measurement result of the RSRP received from the target cell.

[0129] In one embodiment, the UE receives a mobility command; reduces the priority of the mobility command based on a prioritization configuration; retains the mobility command with reduced priority; and executes the retained mobility command with reduced priority when a mobility operation fails.

[0130] The above flowcharts illustrate example methods that can be implemented in accordance with the principles of the present disclosure, and various changes can be made to the methods illustrated in the flowcharts herein. For example, although shown as a series of steps, the various steps in each figure can overlap, occur in parallel, occur in a different order, or occur multiple times. In another example, steps can be omitted or replaced by other steps.

[0131] Although the present disclosure has been described with exemplary embodiments, various changes and modifications can be suggested to those skilled in the art. The present disclosure is intended to cover such changes and modifications that fall within the scope of the appended claims. None of the descriptions 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 subject matter is defined by the claims.

Claims

1. A user equipment (UE) in a wireless communication system, the UE comprising: a transceiver configured to receive information related to (i) a layer 1 and layer 2 triggered mobility (LTM) configuration and (ii) the applicability of the LTM configuration for failure recovery from LTM; and a processor operably coupled to the transceiver, the processor being configured to: determine based on the information whether the applicability of the LTM configuration for failure recovery from LTM is enabled, determine whether LTM execution has failed, perform a cell selection operation based on the determination of LTM execution failure, determine based on the LTM configuration whether the cell selected in the cell selection operation is an LTM candidate cell, perform LTM execution to the cell based on the determination that the cell is an LTM cell and the determination that the applicability of the LTM configuration for failure recovery from LTM is enabled, and apply the LTM configuration to the cell, wherein the transceiver is further configured to send a random access preamble for performing a random access procedure to the cell.

2. The UE according to claim 1, wherein, The processor is further configured to perform LTM execution to a target cell when (i) a command associated with LTM execution is received and (ii) the condition for performing a conditional handover (CHO) to the target cell is evaluated.

3. The UE according to claim 1, wherein: the transceiver is further configured to receive priority configuration information indicating a mobility operation of an LTM operation, a handover (HO) operation, or a CHO operation; the priority configuration information includes an indication indicating which mobility operation among the mobility operations is prioritized; and the priority configuration information includes an indicator indicating the priority level of each mobility operation.

4. The UE according to claim 1, wherein: the transceiver is further configured to receive (i) a plurality of mobility commands and (ii) priority configuration information; the processor is further configured to: identify, based on the priority configuration information, the prioritized mobility command from the plurality of mobility commands, and execute the mobility command.

5. The UE according to claim 1, wherein: the transceiver is further configured to receive at least one mobility command; the processor is further configured to: prioritize the at least one mobility command based on a condition associated with a target cell; the condition is determined based on a measurement result of a timing advance (TA) of the target cell or a reference signal received power (RSRP) received from the target cell; reduce the priority of the mobility command based on the prioritization configuration, retain the mobility command with the reduced priority, and execute the retained mobility command with the reduced priority when the mobility operation fails.

6. A method for a user equipment (UE) in a wireless communication system, the method comprising: receiving information related to (i) a layer 1 and layer 2 triggered mobility (LTM) configuration and (ii) the applicability of the LTM configuration for failure recovery from LTM; determining based on the information whether the applicability of the LTM configuration for failure recovery from LTM is enabled; determining whether LTM execution has failed; performing a cell selection operation based on the determination of LTM execution failure; Based on the LTM configuration, determine whether the cell selected in the cell selection operation is an LTM candidate cell; Based on the determination that the cell is an LTM cell and the determination that the applicability of the LTM configuration for fault recovery from LTM execution is enabled, perform LTM execution to the cell; Apply the LTM configuration to the cell; And Send a random access preamble for performing a random access procedure to the cell.

7. The method according to claim 6, further comprising: When (i) a command associated with LTM execution is received and (ii) the conditions for performing a conditional handover (CHO) to the target cell are evaluated, perform LTM execution to the target cell.

8. The method according to claim 6, further comprising: Receive priority configuration information for mobility operations indicating LTM operations, HO operations, or CHO operations, where the priority configuration information includes an indication that a mobility operation among the mobility operations is prioritized.

9. The method according to claim 6 further comprises: Receive priority configuration information for mobility operations indicating LTM operations, HO operations, and CHO operations, where the priority configuration information includes an indicator indicating the priority level of each mobility operation.

10. The method according to claim 6, further comprising: Receive (i) a plurality of mobility commands and (ii) priority configuration information; Based on the priority configuration information, identify the prioritized mobility commands from the plurality of mobility commands; And Execute the mobility commands.

11. The method according to claim 6, further comprising: Receive at least one mobility command; Prioritize the at least one mobility command based on conditions associated with the target cell; Based on a prioritization configuration, lower the priority of the mobility command; Retain the mobility command with the lowered priority; And When a mobility operation fails, execute the retained mobility command with the lowered priority, where the conditions are determined based on the timing advance (TA) of the target cell or the measurement result of the reference signal received power (RSRP) received from the target cell.

12. A base station (BS) in a wireless communication system, the BS comprising: A processor configured to generate information indicating whether the applicability of the layer 1 and layer 2 triggered mobility (LTM) configuration for fault recovery from LTM execution is enabled; And A transceiver configured to send information related to (i) the LTM configuration and (ii) the applicability of the LTM configuration for fault recovery from LTM execution, wherein: Based on the determination of an LTM execution failure, perform a cell selection operation, Based on the LTM configuration, determine whether the cell selected in the cell selection operation is an LTM candidate cell, Based on the determination that the cell is an LTM cell and the determination that the applicability of the LTM configuration for fault recovery from LTM execution is enabled, perform LTM execution to the cell, Apply the LTM configuration to the cell, and A random access preamble is sent to the cell for performing a random access procedure.

13. The BS according to claim 12, wherein: The transceiver is further configured to send priority configuration information for mobility operations indicating LTM operations, HO operations, or CHO operations; The priority configuration information includes an indication that a mobility operation among the mobility operations is prioritized; and The priority configuration information includes an indicator indicating the priority level of each mobility operation.

14. The BS according to claim 12, wherein: The transceiver is further configured to send (i) a plurality of mobility commands and (ii) priority configuration information; Based on the priority configuration information, identify the prioritized mobility commands from the plurality of mobility commands; And The mobility commands are executed.

15. The BS according to claim 12, wherein: The transceiver is further configured to send at least one mobility command; The at least one mobility command is prioritized based on conditions associated with the target cell; The conditions are determined based on the timing advance (TA) of the target cell or the measurement result of the reference signal received power (RSRP) received from the target cell; Based on the prioritization configuration, reduce the priority of the mobility command; The mobility command with reduced priority is retained; And When a mobility operation fails, execute the retained mobility command with reduced priority.

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