Handling of repeated fast recovery in wireless communications

Abstract

The present disclosure provides a method comprising: receiving candidate configurations for conditional mobility and candidate configurations for cell switch; detecting a failure; performing a first cell selection based on detecting the failure; based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, performing a cell switch execution to the candidate cell; and removing the candidate configurations for conditional mobility based on performing the cell switch execution.

Description

HANDLING OF REPEATED FAST RECOVERY IN WIRELESS COMMUNICATIONS

[0001] The present disclosure is related to handling of repeated fast recovery in wireless communications.

[0002] 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) is a technology for enabling high-speed packet communications. Many schemes have been proposed for the LTE objective including those that aim to reduce user and provider costs, improve service quality, and expand and improve coverage and system capacity. The 3GPP LTE requires reduced cost per bit, increased service availability, flexible use of a frequency band, a simple structure, an open interface, and adequate power consumption of a terminal as an upper-level requirement.

[0003] Work has started in International Telecommunication Union (ITU) and 3GPP to develop requirements and specifications for New Radio (NR) systems. 3GPP has to identify and develop the technology components needed for successfully standardizing the new RAT timely satisfying both the urgent market needs, and the more long-term requirements set forth by the ITU Radio communication sector (ITU-R) International Mobile Telecommunications (IMT)-2020 process. Further, the NR should be able to use any spectrum band ranging at least up to 100 GHz that may be made available for wireless communications even in a more distant future.

[0004] The NR targets a single technical framework addressing all usage scenarios, requirements and deployment scenarios including enhanced Mobile BroadBand (eMBB), massive Machine Type Communications (mMTC), Ultra-Reliable and Low Latency Communications (URLLC), etc. The NR shall be inherently forward compatible.

[0005] In wireless communications, when a failure occurs, a user equipment (UE) may perform a fast recovery procedure or a connection re-establishment procedure. After the UE performs fast recovery procedure, the fast recovery condition may be satisfied again, which may lead to repeating a fast recovery procedure.

[0006] An aspect of the present disclosure is to provide method and apparatus for handling of repeated fast recovery in a wireless communication system.

[0007] According to an embodiment of the present disclosure, a method comprising: receiving one or more candidate configurations for conditional mobility and one or more candidate configurations for cell switch, wherein each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch is related to a corresponding candidate cell; detecting a failure; performing a first cell selection based on detecting the failure; based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, performing a cell switch execution to the candidate cell; and removing the one or more candidate configurations for conditional mobility based on performing the cell switch execution, is provided.

[0008] According to an embodiment of the present disclosure, a method comprising: transmitting, to a user equipment (UE), more candidate configurations for conditional mobility and one or more candidate configurations for cell switch, wherein each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch is related to a corresponding candidate cell, and wherein the UE is configured to perform operations comprising: detecting a failure; performing a first cell selection based on detecting the failure; based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, performing a cell switch execution to the candidate cell; and removing the one or more candidate configurations for conditional mobility based on performing the cell switch execution, is provided.

[0009] According to various embodiments, apparatuses to implement the above methods are provided.

[0010] The present disclosure may have various advantageous effects.

[0011] For example, UE discards / removes the stored conditional reconfigurations (i.e., stored candidate configurations for conditional mobility) when performing LTM-based recovery. To this end, the data interruption can be reduced by preventing repeated fast recovery based on the stored conditional reconfigurations.

[0012] Advantageous effects which can be obtained through specific embodiments of the present disclosure are not limited to the advantageous effects listed above. For example, there may be a variety of technical effects that a person having ordinary skill in the related art can understand and / or derive from the present disclosure. Accordingly, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that may be understood or derived from the technical features of the present disclosure.

[0013] FIG. 1 shows an example of a communication system to which implementations of the present disclosure is applied.

[0014] FIG. 2 shows an example of wireless devices to which implementations of the present disclosure is applied.

[0015] FIG. 3 shows an example of UE to which implementations of the present disclosure is applied.

[0016] FIGs. 4 and 5 show an example of protocol stacks in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

[0017] FIG. 6 shows a frame structure in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

[0018] FIG. 7 shows a data flow example in the 3GPP NR system to which implementations of the present disclosure is applied.

[0019] FIG. 8 shows an example of a conditional mobility procedure according to an embodiment of the present disclosure.

[0020] FIG. 9 shows an example of a signaling procedure for LTM according to an embodiment of the present disclosure.

[0021] FIG. 10 shows an example of a failure recovery procedure according to an embodiment of the present disclosure.

[0022] FIG. 11 shows an example of a method performed by a UE according to an embodiment of the present disclosure.

[0023] FIG. 12 shows an example of a signal flow between a UE and a network node according to an embodiment of the present disclosure.

[0024] FIG. 13 shows an example of a method for notifying a candidate configuration that is applied for LTM / cell switch according to an embodiment of the present disclosure.

[0025] The following techniques, apparatuses, and systems may be applied to a variety of wireless multiple access systems. Examples of the multiple access systems include a Code Division Multiple Access (CDMA) system, a Frequency Division Multiple Access (FDMA) system, a Time Division Multiple Access (TDMA) system, an Orthogonal Frequency Division Multiple Access (OFDMA) system, a Single Carrier Frequency Division Multiple Access (SC-FDMA) system, and a Multi Carrier Frequency Division Multiple Access (MC-FDMA) system. CDMA may be embodied through radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be embodied through radio technology such as Global System for Mobile communications (GSM), General Packet Radio Service (GPRS), or Enhanced Data rates for GSM Evolution (EDGE). OFDMA may be embodied through radio technology such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or Evolved UTRA (E-UTRA). UTRA is a part of a Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA in downlink (DL) and SC-FDMA in uplink (UL). Evolution of 3GPP LTE includes LTE-Advanced (LTE-A), LTE-A Pro, and / or 5G New Radio (NR).

[0026] For convenience of description, implementations of the present disclosure are mainly described in regards to a 3GPP based wireless communication system. However, the technical features of the present disclosure are not limited thereto. For example, although the following detailed description is given based on a mobile communication system corresponding to a 3GPP based wireless communication system, aspects of the present disclosure that are not limited to 3GPP based wireless communication system are applicable to other mobile communication systems.

[0027] For terms and technologies which are not specifically described among the terms of and technologies employed in the present disclosure, the wireless communication standard documents published before the present disclosure may be referenced.

[0028] In the present disclosure, "A or B" may mean "only A", "only B", or "both A and B". In other words, "A or B" in the present disclosure may be interpreted as "A and / or B". For example, "A, B or C" in the present disclosure may mean "only A", "only B", "only C", or "any combination of A, B and C".

[0029] In the present disclosure, slash ( / ) or comma (,) may mean "and / or". For example, "A / B" may mean "A and / or B". Accordingly, "A / B" may mean "only A", "only B", or "both A and B". For example, "A, B, C" may mean "A, B or C".

[0030] In the present disclosure, "at least one of A and B" may mean "only A", "only B" or "both A and B". In addition, the expression "at least one of A or B" or "at least one of A and / or B" in the present disclosure may be interpreted as same as "at least one of A and B".

[0031] In addition, in the present disclosure, "at least one of A, B and C" may mean "only A", "only B", "only C", or "any combination of A, B and C". In addition, "at least one of A, B or C" or "at least one of A, B and / or C" may mean "at least one of A, B and C".

[0032] Also, parentheses used in the present disclosure may mean "for example". In detail, when it is shown as "control information (PDCCH)", "PDCCH" may be proposed as an example of "control information". In other words, "control information" in the present disclosure is not limited to "PDCCH", and "PDCCH" may be proposed as an example of "control information". In addition, even when shown as "control information (i.e., PDCCH)", "PDCCH" may be proposed as an example of "control information".

[0033] Technical features that are separately described in one drawing in the present disclosure may be implemented separately or simultaneously.

[0034] Although not limited thereto, various descriptions, functions, procedures, suggestions, methods and / or operational flowcharts of the present disclosure disclosed herein can be applied to various fields requiring wireless communication and / or connection (e.g., 5G) between devices.

[0035] Hereinafter, the present disclosure will be described in more detail with reference to drawings. The same reference numerals in the following drawings and / or descriptions may refer to the same and / or corresponding hardware blocks, software blocks, and / or functional blocks unless otherwise indicated.

[0036] FIG. 1 shows an example of a communication system to which implementations of the present disclosure is applied.

[0037] The 5G usage scenarios shown in FIG. 1 are only exemplary, and the technical features of the present disclosure can be applied to other 5G usage scenarios which are not shown in FIG. 1.

[0038] Three main requirement categories for 5G include (1) a category of enhanced Mobile BroadBand (eMBB), (2) a category of massive Machine Type Communication (mMTC), and (3) a category of Ultra-Reliable and Low Latency Communications (URLLC).

[0039] Referring to FIG. 1, the communication system 1 includes wireless devices 100a to 100f, Base Stations (BSs) 200, and a network 300. Although FIG. 1 illustrates a 5G network as an example of the network of the communication system 1, the implementations of the present disclosure are not limited to the 5G system, and can be applied to the future communication system beyond the 5G system.

[0040] The BSs 200 and the network 300 may be implemented as wireless devices and a specific wireless device may operate as a BS / network node with respect to other wireless devices.

[0041] The wireless devices 100a to 100f represent devices performing communication using Radio Access Technology (RAT) (e.g., 5G NR or LTE) and may be referred to as communication / radio / 5G devices. The wireless devices 100a to 100f may include, without being limited to, a robot 100a, vehicles 100b-1 and 100b-2, an eXtended Reality (XR) device 100c, a hand-held device 100d, a home appliance 100e, an Internet-of-Things (IoT) device 100f, and an Artificial Intelligence (AI) device / server 400. For example, the vehicles may include a vehicle having a wireless communication function, an autonomous driving vehicle, and a vehicle capable of performing communication between vehicles. The vehicles may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). The XR device may include an Augmented Reality (AR) / Virtual Reality (VR) / Mixed Reality (MR) device and may be implemented in the form of a Head-Mounted Device (HMD), a Head-Up Display (HUD) mounted in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, etc. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), and a computer (e.g., a notebook). The home appliance may include a TV, a refrigerator, and a washing machine. The IoT device may include a sensor and a smartmeter.

[0042] In the present disclosure, the wireless devices 100a to 100f may be called User Equipments (UEs). A UE may include, for example, a cellular phone, a smartphone, a laptop computer, a digital broadcast terminal, a Personal Digital Assistant (PDA), a Portable Multimedia Player (PMP), a navigation system, a slate Personal Computer (PC), a tablet PC, an ultrabook, a vehicle, a vehicle having an autonomous traveling function, a connected car, an UAV, an AI module, a robot, an AR device, a VR device, an MR device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a FinTech device (or a financial device), a security device, a weather / environment device, a device related to a 5G service, or a device related to a fourth industrial revolution field.

[0043] The wireless devices 100a to 100f may be connected to the network 300 via the BSs 200. An AI technology may be applied to the wireless devices 100a to 100f and the wireless devices 100a to 100f may be connected to the AI server 400 via the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, and a beyond-5G network. Although the wireless devices 100a to 100f may communicate with each other through the BSs 200 / network 300, the wireless devices 100a to 100f may perform direct communication (e.g., sidelink communication) with each other without passing through the BSs 200 / network 300. For example, the vehicles 100b-1 and 100b-2 may perform direct communication (e.g., Vehicle-to-Vehicle (V2V) / Vehicle-to-everything (V2X) communication). The IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

[0044] Wireless communication / connections 150a, 150b and 150c may be established between the wireless devices 100a to 100f and / or between wireless device 100a to 100f and BS 200 and / or between BSs 200. Herein, the wireless communication / connections may be established through various RATs (e.g., 5G NR) such as uplink / downlink communication 150a, sidelink communication (or Device-to-Device (D2D) communication) 150b, inter-base station communication 150c (e.g., relay, Integrated Access and Backhaul (IAB)), etc. The wireless devices 100a to 100f and the BSs 200 / the wireless devices 100a to 100f may transmit / receive radio signals to / from each other through the wireless communication / connections 150a, 150b and 150c. For example, the wireless communication / connections 150a, 150b and 150c may transmit / receive signals through various physical channels. To this end, at least a part of various configuration information configuring processes, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, and resource mapping / de-mapping), and resource allocating processes, for transmitting / receiving radio signals, may be performed based on the various proposals of the present disclosure.

[0045] NR supports multiples numerologies (and / or multiple Sub-Carrier Spacings (SCS)) to support various 5G services. For example, if SCS is 15 kHz, wide area can be supported in traditional cellular bands, and if SCS is 30 kHz / 60 kHz, dense-urban, lower latency, and wider carrier bandwidth can be supported. If SCS is 60 kHz or higher, bandwidths greater than 24.25 GHz can be supported to overcome phase noise.

[0046] The NR frequency band may be defined as two types of frequency range, i.e., Frequency Range 1 (FR1) and Frequency Range 2 (FR2). The numerical value of the frequency range may be changed. For example, the frequency ranges of the two types (FR1 and FR2) may be as shown in Table 1 below. For ease of explanation, in the frequency ranges used in the NR system, FR1 may mean "sub 6 GHz range", FR2 may mean "above 6 GHz range," and may be referred to as millimeter Wave (mmW).

[0047] Frequency Range designationCorresponding frequency rangeSubcarrier SpacingFR1450MHz - 6000MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0048] As mentioned above, the numerical value of the frequency range of the NR system may be changed. For example, FR1 may include a frequency band of 410MHz to 7125MHz as shown in Table 2 below. That is, FR1 may include a frequency band of 6GHz (or 5850, 5900, 5925 MHz, etc.) or more. For example, a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or more included in FR1 may include an unlicensed band. Unlicensed bands may be used for a variety of purposes, for example for communication for vehicles (e.g., autonomous driving).

[0049] Frequency Range designationCorresponding frequency rangeSubcarrier SpacingFR1410MHz - 7125MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0050] Here, the radio communication technologies implemented in the wireless devices in the present disclosure may include NarrowBand IoT (NB-IoT) technology for low-power communication as well as LTE, NR and 6G. For example, NB-IoT technology may be an example of Low Power Wide Area Network (LPWAN) technology, may be implemented in specifications such as LTE Cat NB1 and / or LTE Cat NB2, and may not be limited to the above-mentioned names. Additionally and / or alternatively, the radio communication technologies implemented in the wireless devices in the present disclosure may communicate based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and be called by various names such as enhanced MTC (eMTC). For example, LTE-M technology may be implemented in at least one of the various specifications, such as 1) LTE Cat 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-bandwidth limited (non-BL), 5) LTE-MTC, 6) LTE Machine Type Communication, and / or 7) LTE M, and may not be limited to the above-mentioned names. Additionally and / or alternatively, the radio communication technologies implemented in the wireless devices in the present disclosure may include at least one of ZigBee, Bluetooth, and / or LPWAN which take into account low-power communication, and may not be limited to the above-mentioned names. For example, ZigBee technology may generate Personal Area Networks (PANs) associated with small / low-power digital communication based on various specifications such as IEEE 802.15.4 and may be called various names.FIG. 2 shows an example of wireless devices to which implementations of the present disclosure is applied.

[0051] In FIG. 2, The first wireless device 100 and / or the second wireless device 200 may be implemented in various forms according to use cases / services. For example, {the first wireless device 100 and the second wireless device 200} may correspond to at least one of {the wireless device 100a to 100f and the BS 200}, {the wireless device 100a to 100f and the wireless device 100a to 100f} and / or {the BS 200 and the BS 200} of FIG. 1. The first wireless device 100 and / or the second wireless device 200 may be configured by various elements, devices / parts, and / or modules.

[0052] The first wireless device 100 may include at least one transceiver, such as a transceiver 106, at least one processing chip, such as a processing chip 101, and / or one or more antennas 108.

[0053] The processing chip 101 may include at least one processor, such a processor 102, and at least one memory, such as a memory 104. Additional and / or alternatively, the memory 104 may be placed outside of the processing chip 101.

[0054] The processor 102 may control the memory 104 and / or the transceiver 106 and may be adapted to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts described in the present disclosure. For example, the processor 102 may process information within the memory 104 to generate first information / signals and then transmit radio signals including the first information / signals through the transceiver 106. The processor 102 may receive radio signals including second information / signals through the transceiver 106 and then store information obtained by processing the second information / signals in the memory 104.

[0055] The memory 104 may be operably connectable to the processor 102. The memory 104 may store various types of information and / or instructions. The memory 104 may store a firmware and / or a software code 105 which implements codes, commands, and / or a set of commands that, when executed by the processor 102, perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. For example, the firmware and / or the software code 105 may implement instructions that, when executed by the processor 102, perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. For example, the firmware and / or the software code 105 may control the processor 102 to perform one or more protocols. For example, the firmware and / or the software code 105 may control the processor 102 to perform one or more layers of the radio interface protocol.

[0056] Herein, the processor 102 and the memory 104 may be a part of a communication modem / circuit / chip designed to implement RAT (e.g., LTE or NR). The transceiver 106 may be connected to the processor 102 and transmit and / or receive radio signals through one or more antennas 108. Each of the transceiver 106 may include a transmitter and / or a receiver. The transceiver 106 may be interchangeably used with Radio Frequency (RF) unit(s). In the present disclosure, the first wireless device 100 may represent a communication modem / circuit / chip.

[0057] The second wireless device 200 may include at least one transceiver, such as a transceiver 206, at least one processing chip, such as a processing chip 201, and / or one or more antennas 208.

[0058] The processing chip 201 may include at least one processor, such a processor 202, and at least one memory, such as a memory 204. Additional and / or alternatively, the memory 204 may be placed outside of the processing chip 201.

[0059] The processor 202 may control the memory 204 and / or the transceiver 206 and may be adapted to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts described in the present disclosure. For example, the processor 202 may process information within the memory 204 to generate third information / signals and then transmit radio signals including the third information / signals through the transceiver 206. The processor 202 may receive radio signals including fourth information / signals through the transceiver 106 and then store information obtained by processing the fourth information / signals in the memory 204.

[0060] The memory 204 may be operably connectable to the processor 202. The memory 204 may store various types of information and / or instructions. The memory 204 may store a firmware and / or a software code 205 which implements codes, commands, and / or a set of commands that, when executed by the processor 202, perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. For example, the firmware and / or the software code 205 may implement instructions that, when executed by the processor 202, perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. For example, the firmware and / or the software code 205 may control the processor 202 to perform one or more protocols. For example, the firmware and / or the software code 205 may control the processor 202 to perform one or more layers of the radio interface protocol.

[0061] Herein, the processor 202 and the memory 204 may be a part of a communication modem / circuit / chip designed to implement RAT (e.g., LTE or NR). The transceiver 206 may be connected to the processor 202 and transmit and / or receive radio signals through one or more antennas 208. Each of the transceiver 206 may include a transmitter and / or a receiver. The transceiver 206 may be interchangeably used with RF unit. In the present disclosure, the second wireless device 200 may represent a communication modem / circuit / chip.

[0062] Hereinafter, hardware elements of the wireless devices 100 and 200 will be described more specifically. One or more protocol layers may be implemented by, without being limited to, one or more processors 102 and 202. For example, the one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as Physical (PHY) layer, Media Access Control (MAC) layer, Radio Link Control (RLC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Resource Control (RRC) layer, and Service Data Adaptation Protocol (SDAP) layer). The one or more processors 102 and 202 may generate one or more Protocol Data Units (PDUs), one or more Service Data Unit (SDUs), messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. The one or more processors 102 and 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure and provide the generated signals to the one or more transceivers 106 and 206. The one or more processors 102 and 202 may receive the signals (e.g., baseband signals) from the one or more transceivers 106 and 206 and acquire the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure.

[0063] The one or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. The one or more processors 102 and 202 may be implemented by hardware, firmware, software, or a combination thereof. As an example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in the one or more processors 102 and 202. For example, the one or more processors 102 and 202 may be configured by a set of a communication control processor, an Application Processor (AP), an Electronic Control Unit (ECU), a Central Processing Unit (CPU), a Graphic Processing Unit (GPU), and a memory control processor.

[0064] The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 and store various types of data, signals, messages, information, programs, code, instructions, and / or commands. The one or more memories 104 and 204 may be configured by Random Access Memory (RAM), Dynamic RAM (DRAM), Read-Only Memory (ROM), electrically Erasable Programmable Read-Only Memory (EPROM), flash memory, volatile memory, non-volatile memory, hard drive, register, cash memory, computer-readable storage medium, and / or combinations thereof. The one or more memories 104 and 204 may be located at the interior and / or exterior of the one or more processors 102 and 202. The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 through various technologies such as wired or wireless connection.

[0065] The one or more transceivers 106 and 206 may transmit user data, control information, and / or radio signals / channels, mentioned in the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure, to one or more other devices. The one or more transceivers 106 and 206 may receive user data, control information, and / or radio signals / channels, mentioned in the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure, from one or more other devices. For example, the one or more transceivers 106 and 206 may be connected to the one or more processors 102 and 202 and transmit and receive radio signals. For example, the one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may transmit user data, control information, or radio signals to one or more other devices. The one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may receive user data, control information, or radio signals from one or more other devices.

[0066] The one or more transceivers 106 and 206 may be connected to the one or more antennas 108 and 208. Additionally and / or alternatively, the one or more transceivers 106 and 206 may include one or more antennas 108 and 208. The one or more transceivers 106 and 206 may be adapted to transmit and receive user data, control information, and / or radio signals / channels, mentioned in the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure, through the one or more antennas 108 and 208. In the present disclosure, the one or more antennas 108 and 208 may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports).

[0067] The one or more transceivers 106 and 206 may convert received user data, control information, radio signals / channels, etc., from RF band signals into baseband signals in order to process received user data, control information, radio signals / channels, etc., using the one or more processors 102 and 202. The one or more transceivers 106 and 206 may convert the user data, control information, radio signals / channels, etc., processed using the one or more processors 102 and 202 from the base band signals into the RF band signals. To this end, the one or more transceivers 106 and 206 may include (analog) oscillators and / or filters. For example, the one or more transceivers 106 and 206 can up-convert OFDM baseband signals to OFDM signals by their (analog) oscillators and / or filters under the control of the one or more processors 102 and 202 and transmit the up-converted OFDM signals at the carrier frequency. The one or more transceivers 106 and 206 may receive OFDM signals at a carrier frequency and down-convert the OFDM signals into OFDM baseband signals by their (analog) oscillators and / or filters under the control of the one or more processors 102 and 202.

[0068] Although not shown in FIG. 2, the wireless devices 100 and 200 may further include additional components. The additional components 140 may be variously configured according to types of the wireless devices 100 and 200. For example, the additional components 140 may include at least one of a power unit / battery, an Input / Output (I / O) device (e.g., audio I / O port, video I / O port), a driving device, and a computing device. The additional components 140 may be coupled to the one or more processors 102 and 202 via various technologies, such as a wired or wireless connection.

[0069] In the implementations of the present disclosure, a UE may operate as a transmitting device in Uplink (UL) and as a receiving device in Downlink (DL). In the implementations of the present disclosure, a BS may operate as a receiving device in UL and as a transmitting device in DL. Hereinafter, for convenience of description, it is mainly assumed that the first wireless device 100 acts as the UE, and the second wireless device 200 acts as the BS. For example, the processor(s) 102 connected to, mounted on or launched in the first wireless device 100 may be adapted to perform the UE behavior according to an implementation of the present disclosure or control the transceiver(s) 106 to perform the UE behavior according to an implementation of the present disclosure. The processor(s) 202 connected to, mounted on or launched in the second wireless device 200 may be adapted to perform the BS behavior according to an implementation of the present disclosure or control the transceiver(s) 206 to perform the BS behavior according to an implementation of the present disclosure.

[0070] In the present disclosure, a BS is also referred to as a node B (NB), an eNode B (eNB), or a gNB.

[0071] FIG. 3 shows an example of UE to which implementations of the present disclosure is applied.

[0072] Referring to FIG. 3, a UE 100 may correspond to the first wireless device 100 of FIG. 2.

[0073] A UE 100 includes a processor 102, a memory 104, a transceiver 106, one or more antennas 108, a power management module 141, a battery 142, a display 143, a keypad 144, a Subscriber Identification Module (SIM) card 145, a speaker 146, and a microphone 147.

[0074] The processor 102 may be adapted to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. The processor 102 may be adapted to control one or more other components of the UE 100 to implement the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. Layers of the radio interface protocol may be implemented in the processor 102. The processor 102 may include ASIC, other chipset, logic circuit and / or data processing device. The processor 102 may be an application processor. The processor 102 may include at least one of DSP, CPU, GPU, a modem (modulator and demodulator). An example of the processor 102 may be found in SNAPDRAGONTMseries of processors made by Qualcomm®, EXYNOSTMseries of processors made by Samsung®, A series of processors made by Apple®, HELIOTMseries of processors made by MediaTek®, ATOMTMseries of processors made by Intel®or a corresponding next generation processor.

[0075] The memory 104 is operatively coupled with the processor 102 and stores a variety of information to operate the processor 102. The memory 104 may include ROM, RAM, flash memory, memory card, storage medium and / or other storage device. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, etc.) that perform the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed in the present disclosure. The modules can be stored in the memory 104 and executed by the processor 102. The memory 104 can be implemented within the processor 102 or external to the processor 102 in which case those can be communicatively coupled to the processor 102 via various means as is known in the art.

[0076] The transceiver 106 is operatively coupled with the processor 102, and transmits and / or receives a radio signal. The transceiver 106 includes a transmitter and a receiver. The transceiver 106 may include baseband circuitry to process radio frequency signals. The transceiver 106 controls the one or more antennas 108 to transmit and / or receive a radio signal.

[0077] The power management module 141 manages power for the processor 102 and / or the transceiver 106. The battery 142 supplies power to the power management module 141.

[0078] The display 143 outputs results processed by the processor 102. The keypad 144 receives inputs to be used by the processor 102. The keypad 144 may be shown on the display 143.

[0079] The SIM card 145 is an　integrated circuit　that is intended to　securely store the　International Mobile Subscriber Identity　(IMSI) number and its related　key, which are used to identify and authenticate subscribers on　mobile telephony　devices (such as　mobile phones　and　computers). It is also possible to store contact information on many SIM cards.

[0080] The speaker 146 outputs sound-related results processed by the processor 102. The microphone 147 receives sound-related inputs to be used by the processor 102.

[0081] FIGs. 4 and 5 show an example of protocol stacks in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

[0082] In particular, FIG. 4 illustrates an example of a radio interface user plane protocol stack between a UE and a BS and FIG. 5 illustrates an example of a radio interface control plane protocol stack between a UE and a BS. The control plane refers to a path through which control messages used to manage call by a UE and a network are transported. The user plane refers to a path through which data generated in an application layer, for example, voice data or Internet packet data are transported. Referring to FIG. 4, the user plane protocol stack may be divided into Layer 1 (L1, for example PHY layer) and Layer 2 (L2, for example MAC / RLC / PDCP layer). Referring to FIG. 5, the control plane protocol stack may be divided into Layer 1 (L1, for example PHY layer), Layer 2 (L2, for example MAC / RLC / PDCP layer), Layer 3 (L3, for example an RRC layer), and a non-access stratum (NAS) layer. Layer 1, Layer 2 and Layer 3 are referred to as an access stratum (AS).

[0083] In the 3GPP LTE system, the Layer 2 is split into the following sublayers: MAC, RLC, and PDCP. In the 3GPP NR system, the Layer 2 is split into the following sublayers: MAC, RLC, PDCP and SDAP. The PHY layer offers to the MAC sublayer transport channels, the MAC sublayer offers to the RLC sublayer logical channels, the RLC sublayer offers to the PDCP sublayer RLC channels, the PDCP sublayer offers to the SDAP sublayer radio bearers. The SDAP sublayer offers to 5G core network quality of service (QoS) flows.

[0084] In the 3GPP NR system, the main services and functions of the MAC sublayer include: mapping between logical channels and transport channels; multiplexing / de-multiplexing of MAC SDUs belonging to one or different logical channels into / from transport blocks (TB) delivered to / from the physical layer on transport channels; scheduling information reporting; error correction through hybrid automatic repeat request (HARQ) (one HARQ entity per cell in case of carrier aggregation (CA)); priority handling between UEs by means of dynamic scheduling; priority handling between logical channels of one UE by means of logical channel prioritization; padding. A single MAC entity may support multiple numerologies, transmission timings and cells. Mapping restrictions in logical channel prioritization control which numerology(ies), cell(s), and transmission timing(s) a logical channel can use.

[0085] Different kinds of data transfer services are offered by MAC. To accommodate different kinds of data transfer services, multiple types of logical channels are defined, i.e., each supporting transfer of a particular type of information. Each logical channel type is defined by what type of information is transferred. Logical channels are classified into two groups: control channels and traffic channels. Control channels are used for the transfer of control plane information only, and traffic channels are used for the transfer of user plane information only. Broadcast control channel (BCCH) is a downlink logical channel for broadcasting system control information, paging control channel (PCCH) is a downlink logical channel that transfers paging information, system information change notifications and indications of ongoing public warning service (PWS) broadcasts, common control channel (CCCH) is a logical channel for transmitting control information between UEs and network and used for UEs having no RRC connection with the network, and dedicated control channel (DCCH) is a point-to-point bi-directional logical channel that transmits dedicated control information between a UE and the network and used by UEs having an RRC connection. Dedicated traffic channel (DTCH) is a point-to-point logical channel, dedicated to one UE, for the transfer of user information. A DTCH can exist in both uplink and downlink. In downlink, the following connections between logical channels and transport channels exist: BCCH can be mapped to broadcast channel (BCH); BCCH can be mapped to downlink shared channel (DL-SCH); PCCH can be mapped to paging channel (PCH); CCCH can be mapped to DL-SCH; DCCH can be mapped to DL-SCH; and DTCH can be mapped to DL-SCH. In uplink, the following connections between logical channels and transport channels exist: CCCH can be mapped to uplink shared channel (UL-SCH); DCCH can be mapped to UL-SCH; and DTCH can be mapped to UL-SCH.

[0086] The RLC sublayer supports three transmission modes: transparent mode (TM), unacknowledged mode (UM), and acknowledged node (AM). The RLC configuration is per logical channel with no dependency on numerologies and / or transmission durations. In the 3GPP NR system, the main services and functions of the RLC sublayer depend on the transmission mode and include: transfer of upper layer PDUs; sequence numbering independent of the one in PDCP (UM and AM); error correction through ARQ (AM only); segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs; reassembly of SDU (AM and UM); duplicate detection (AM only); RLC SDU discard (AM and UM); RLC re-establishment; protocol error detection (AM only).

[0087] In the 3GPP NR system, the main services and functions of the PDCP sublayer for the user plane include: sequence numbering; header compression and decompression using robust header compression (ROHC); transfer of user data; reordering and duplicate detection; in-order delivery; PDCP PDU routing (in case of split bearers); retransmission of PDCP SDUs; ciphering, deciphering and integrity protection; PDCP SDU discard; PDCP re-establishment and data recovery for RLC AM; PDCP status reporting for RLC AM; duplication of PDCP PDUs and duplicate discard indication to lower layers. The main services and functions of the PDCP sublayer for the control plane include: sequence numbering; ciphering, deciphering and integrity protection; transfer of control plane data; reordering and duplicate detection; in-order delivery; duplication of PDCP PDUs and duplicate discard indication to lower layers.

[0088] In the 3GPP NR system, the main services and functions of SDAP include: mapping between a QoS flow and a data radio bearer; marking QoS flow ID (QFI) in both DL and UL packets. A single protocol entity of SDAP is configured for each individual PDU session.

[0089] In the 3GPP NR system, the main services and functions of the RRC sublayer include: broadcast of system information related to AS and NAS; paging initiated by 5GC or NG-RAN; establishment, maintenance and release of an RRC connection between the UE and NG-RAN; security functions including key management; establishment, configuration, maintenance and release of signaling radio bearers (SRBs) and data radio bearers (DRBs); mobility functions (including: handover and context transfer, UE cell selection and reselection and control of cell selection and reselection, inter-RAT mobility); QoS management functions; UE measurement reporting and control of the reporting; detection of and recovery from radio link failure; NAS message transfer to / from NAS from / to UE.

[0090] FIG. 6 shows a frame structure in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

[0091] The frame structure shown in FIG. 6 is purely exemplary and the number of subframes, the number of slots, and / or the number of symbols in a frame may be variously changed. In the 3GPP based wireless communication system, OFDM numerologies (e.g., subcarrier spacing (SCS), transmission time interval (TTI) duration) may be differently configured between a plurality of cells aggregated for one UE. For example, if a UE is configured with different SCSs for cells aggregated for the cell, an (absolute time) duration of a time resource (e.g., a subframe, a slot, or a TTI) including the same number of symbols may be different among the aggregated cells. Herein, symbols may include OFDM symbols (or CP-OFDM symbols), SC-FDMA symbols (or discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbols).

[0092] Referring to FIG. 6, downlink and uplink transmissions are organized into frames. Each frame has Tf= 10ms duration. Each frame is divided into two half-frames, where each of the half-frames has 5ms duration. Each half-frame consists of 5 subframes, where the duration Tsfper subframe is 1ms. Each subframe is divided into slots and the number of slots in a subframe depends on a subcarrier spacing. Each slot includes 14 or 12 OFDM symbols based on a cyclic prefix (CP). In a normal CP, each slot includes 14 OFDM symbols and, in an extended CP, each slot includes 12 OFDM symbols. The numerology is based on exponentially scalable subcarrier spacing βf = 2u*15 kHz.

[0093] Table 3 shows the number of OFDM symbols per slot Nslotsymb, the number of slots per frameNframe,uslot, and the number of slots per subframe Nsubframe,uslotfor the normal CP, according to the subcarrier spacing βf = 2u*15 kHz.

[0094] uNslotsymbNframe,uslotNsubframe,uslot01410111420221440431480841416016

[0095] Table 4 shows the number of OFDM symbols per slot Nslotsymb, the number of slots per frameNframe,uslot, and the number of slots per subframe Nsubframe,uslotfor the extended CP, according to the subcarrier spacing βf = 2u*15 kHz.

[0096] uNslotsymbNframe,uslotNsubframe,uslot212404

[0097] A slot includes plural symbols (e.g., 14 or 12 symbols) in the time domain. For each numerology (e.g., subcarrier spacing) and carrier, a resource grid ofNsize,ugrid,x*NRBscsubcarriers andNsubframe,usymbOFDM symbols is defined, starting at common resource block (CRB)Nstart,ugridindicated by higher-layer signaling (e.g., RRC signaling), whereNsize,ugrid,xis the number of resource blocks (RBs) in the resource grid and the subscript x is DL for downlink and UL for uplink.NRBscis the number of subcarriers per RB. In the 3GPP based wireless communication system,NRBscis 12 generally. There is one resource grid for a given antenna portp, subcarrier spacing configurationu, and transmission direction (DL or UL). The carrier bandwidthNsize,ugridfor subcarrier spacing configurationuis given by the higher-layer parameter (e.g., RRC parameter). Each element in the resource grid for the antenna portpand the subcarrier spacing configurationuis referred to as a resource element (RE) and one complex symbol may be mapped to each RE. Each RE in the resource grid is uniquely identified by an indexkin the frequency domain and an indexlrepresenting a symbol location relative to a reference point in the time domain. In the 3GPP based wireless communication system, an RB is defined by 12 consecutive subcarriers in the frequency domain. As shown in FIG. 6, as SCS doubles, the slot length and symbol length are halved. For example, when SCS is 15kHz, the slot length is 1ms, which is the same as the subframe length. When SCS is 30kHz, the slot length is 0.5ms (=500us), and the symbol length is half of that when the SCS is 15kHz. When SCS is 60kHz, the slot length is 0.25ms (=250us), and the symbol length is half of that when the SCS is 30kHz. When SCS is 120kHz, the slot length is 0.125ms (=125us), and the symbol length is half of that when the SCS is 60kHz. When SCS is 240kHz, the slot length is 0.0625ms (=62.5us), and the symbol length is half of that when the SCS is 120kHz.

[0098] In the 3GPP NR system, RBs are classified into CRBs and physical resource blocks (PRBs). CRBs are numbered from 0 and upwards in the frequency domain for subcarrier spacing configurationu. The center of subcarrier 0 of CRB 0 for subcarrier spacing configurationucoincides with 'point A' which serves as a common reference point for resource block grids. In the 3GPP NR system, PRBs are defined within a bandwidth part (BWP) and numbered from 0 toNsizeBWP,i-1, where i is the number of the bandwidth part. The relation between the physical resource block nPRBin the bandwidth part i and the common resource block nCRBis as follows: nPRB= nCRB+NsizeBWP,i, whereNsizeBWP,iis the common resource block where bandwidth part starts relative to CRB 0. The BWP includes a plurality of consecutive RBs. A carrier may include a maximum of N (e.g., 5) BWPs. A UE may be configured with one or more BWPs on a given component carrier. Only one BWP among BWPs configured to the UE can active at a time. The active BWP defines the UE's operating bandwidth within the cell's operating bandwidth.

[0099] In the present disclosure, the term "cell" may refer to a geographic area to which one or more nodes provide a communication system, or refer to radio resources. A "cell" as a geographic area may be understood as coverage within which a node can provide service using a carrier and a "cell" as radio resources (e.g., time-frequency resources) is associated with bandwidth which is a frequency range configured by the carrier. The "cell" associated with the radio resources is defined by a combination of downlink resources and uplink resources, for example, a combination of a DL component carrier (CC) and a UL CC. The cell may be configured by downlink resources only, or may be configured by downlink resources and uplink resources. Since DL coverage, which is a range within which the node is capable of transmitting a valid signal, and UL coverage, which is a range within which the node is capable of receiving the valid signal from the UE, depends upon a carrier carrying the signal, the coverage of the node may be associated with coverage of the "cell" of radio resources used by the node. Accordingly, the term "cell" may be used to represent service coverage of the node sometimes, radio resources at other times, or a range that signals using the radio resources can reach with valid strength at other times.

[0100] In CA, two or more CCs are aggregated. A UE may simultaneously receive or transmit on one or multiple CCs depending on its capabilities. CA is supported for both contiguous and non-contiguous CCs. When CA is configured, the UE only has one RRC connection with the network. At RRC connection establishment / re-establishment / handover, one serving cell provides the NAS mobility information, and at RRC connection re-establishment / handover, one serving cell provides the security input. This cell is referred to as the primary cell (PCell). The PCell is a cell, operating on the primary frequency, in which the UE either performs the initial connection establishment procedure or initiates the connection re-establishment procedure. Depending on UE capabilities, secondary cells (SCells) can be configured to form together with the PCell a set of serving cells. An SCell is a cell providing additional radio resources on top of special cell (SpCell). The configured set of serving cells for a UE therefore always consists of one PCell and one or more SCells. For dual connectivity (DC) operation, the term SpCell refers to the PCell of the master cell group (MCG) or the primary SCell (PSCell) of the secondary cell group (SCG). An SpCell supports PUCCH transmission and contention-based random access, and is always activated. The MCG is a group of serving cells associated with a master node, comprised of the SpCell (PCell) and optionally one or more SCells. The SCG is the subset of serving cells associated with a secondary node, comprised of the PSCell and zero or more SCells, for a UE configured with DC. For a UE in RRC_CONNECTED not configured with CA / DC, there is only one serving cell comprised of the PCell. For a UE in RRC_CONNECTED configured with CA / DC, the term "serving cells" is used to denote the set of cells comprised of the SpCell(s) and all SCells. In DC, two MAC entities are configured in a UE: one for the MCG and one for the SCG.

[0101] FIG. 7 shows a data flow example in the 3GPP NR system to which implementations of the present disclosure is applied.

[0102] Referring to FIG. 7, "RB" denotes a radio bearer, and "H" denotes a header. Radio bearers are categorized into two groups: DRBs for user plane data and SRBs for control plane data. The MAC PDU is transmitted / received using radio resources through the PHY layer to / from an external device. The MAC PDU arrives to the PHY layer in the form of a transport block.

[0103] In the PHY layer, the uplink transport channels UL-SCH and random access channel (RACH) are mapped to their physical channels physical uplink shared channel (PUSCH) and physical random access channel (PRACH), respectively, and the downlink transport channels DL-SCH, BCH and PCH are mapped to physical downlink shared channel (PDSCH), physical broadcast channel (PBCH) and PDSCH, respectively. In the PHY layer, uplink control information (UCI) is mapped to physical uplink control channel (PUCCH), and downlink control information (DCI) is mapped to physical downlink control channel (PDCCH). A MAC PDU related to UL-SCH is transmitted by a UE via a PUSCH based on an UL grant, and a MAC PDU related to DL-SCH is transmitted by a BS via a PDSCH based on a DL assignment.

[0104] Hereinafter, signaling radio bearers (SRBs) are described.

[0105] SRBs are defined as Radio Bearers (RBs) that are used only for the transmission of RRC and NAS messages. More specifically, the following SRBs are defined:

[0106] - SRB0 is for RRC messages using the CCCH logical channel (except SRB0 of L2 U2N Remote UE);

[0107] - SRB1 is for RRC messages (which may include a piggybacked NAS message) as well as for NAS messages prior to the establishment of SRB2, all using DCCH logical channel (except SRB1 of L2 U2N Remote UE);

[0108] - SRB2 is for NAS messages and for RRC messages which include logged measurement information, all using DCCH logical channel (except SRB2 of L2 U2N Remote UE). SRB2 has a lower priority than SRB1 and may be configured by the network after AS security activation;

[0109] - SRB3 is for specific RRC messages when UE is in (NG)EN-DC or NR-DC, all using DCCH logical channel;

[0110] - SRB4 is for RRC messages which include application layer measurement report information, all using DCCH logical channel. SRB4 has a lower priority than SRB1 and can only be configured by the network after AS security activation.

[0111] - SRB5 is for RRC messages which include application layer measurement report information, all using DCCH logical channel. SRB5 has a lower priority than SRB1 and SRB3 and can only be configured by the SN serving the SCG when the UE is in NR-DC, after AS security activation.

[0112] In downlink, piggybacking of NAS messages is used only for one dependent (i.e., with joint success / failure) procedure:

[0113] bearer establishment / modification / release. In uplink piggybacking of NAS message is used only for transferring the initial NAS message during connection setup and connection resume.

[0114] The NAS messages transferred via SRB2 are also contained in RRC messages, which however do not include any RRC protocol control information.

[0115] Once AS security is activated, all RRC messages on SRB1, SRB2, SRB3, SRB4 and SRB5, including those containing NAS messages, are integrity protected and ciphered by PDCP. NAS independently applies integrity protection and ciphering to the NAS messages.

[0116] Split SRB is supported for all the MR-DC options as well as MP in both SRB1 and SRB2 (split SRB is not supported for SRB0, SRB3, SRB4 and SRB5).

[0117] Hereinafter, contents regarding mobility are described.

[0118] The mobility may comprise PCell change, PSCell change (or, secondary node (SN) change), and / or PSCell addition (or, SN addition).

[0119] In the present disclosure, the term "handover (HO)" may mean PCell change, or may be a broad concept that includes not only PCell change but also PSCell change / addition.

[0120] In the present disclosure, the terms "handover" and "mobility" can be used interchangeably.

[0121] In the present disclosure, the description regarding handover can also be applied to other mobility procedures (e.g., PSCell change / addition).

[0122] There may be at least two types of mobility: network-controlled mobility (or, legacy mobility) and UE-based mobility (or, conditional mobility).

[0123] The network-controlled mobility (or, legacy mobility) is a mobility where the network determines a target cell for mobility, and configures UE with the target cell. The network may transmit, to the UE, anRRCReconfigurationmessage comprising a configuration of the target cell. The UE may execute a mobility to the target cell and / or apply the configuration for the target cell, upon receiving the configuration of the target cell.

[0124] The UE-based mobility (or, conditional mobility) is a mobility where the network configures the UE with a plurality of candidate cells, and the UE determines a target cell which satisfies a mobility execution condition among the plurality of candidate cells. The conditional mobility may comprise at least one of a conditional PCell change / conditional handover (CHO) or a conditional PSCell mobility. The conditional PSCell mobility may comprise conditional PSCell addition / change (CPAC), including conditional PSCell addition (CPA) and / or conditional PSCell change (CPC). The network may transmit, to the UE, anRRCReconfigurationmessage comprisingConditionalReconfigurationinformation element (IE)(or, conditional mobility configuration), which comprises a list of conditional reconfigurations for the plurality of candidate cells. A conditional reconfiguration for a candidate cell may comprise an identifier of the conditional reconfiguration, a mobility execution condition for the candidate cell, and a configuration for the candidate cell. The UE may evaluate the mobility execution conditions for the plurality of candidate cells, and when a mobility execution condition for a candidate cell is satisfied, the UE may consider the candidate cell as a target cell, and execute a mobility to the target cell and / or apply the configuration for the target cell.

[0125] According to various embodiments, the mobility execution condition may be satisfied / met when an entry condition (or, entering condition) for the mobility execution condition is satisfied / met for at least a time-to-trigger (TTT) for the mobility execution condition. The entry condition / entering condition may mean that the mobility execution condition is initially met. Once the entry condition is met, the mobility execution condition will be considered to be met if the entry condition is met for time duration TTT continuously.

[0126] FIG. 8 shows an example of a conditional mobility procedure according to an embodiment of the present disclosure.

[0127] In FIG. 8:

[0128] - the serving BS may be related to a PCell, which may be a source PCell for CHO;

[0129] - the serving BS may be an MN associated with an SN in DC, where the SN may be related to a source PSCell for CPC; and

[0130] - the target cell may be a target PCell for CHO, or a target PSCell for CPA / CPC.

[0131] Referring to FIG. 8, in step S801, UE may receive, from the serving BS, anRRCReconfiguraitonmessage comprising a conditional reconfiguration information element (IE) (i.e.,CondidtionalReconfiguration). The conditional reconfiguration IE may comprise a list of conditional reconfigurations for candidate cells including the target cell. Each conditional reconfiguration in the list may be related to the corresponding candidate cell, and comprises i) an identifier of the corresponding conditional reconfiguration (i.e.,condReconfigId), ii) one or more execution conditions for the corresponding candidate cell (i.e.,condExecutionCond), and / or iii) RRC reconfiguration for the corresponding candidate cell (i.e.,condRRCReconfig) including a configuration of the corresponding candidate cell (e.g., candidate cell configuration / target cell configuration). The one or more execution conditions may comprise CHO execution condition(s), CPA execution condition(s), and / or CPC execution condition(s).

[0132] In step S803, the UE may start evaluating the one or more execution conditions for the candidate cells.

[0133] In step S805, if the target cell satisfies the corresponding execution condition(s), the UE may execute the conditional mobility towards the target cell and / or apply the RRC reconfiguration for the target cell including a configuration of the target cell. When / upon executing the conditional mobility and / or applying the RRC reconfiguration (e.g.,RRCReconfigurationincludingReconfigurationWithSync) for the target cell, the UE may start a timer (e.g., T304 timer). The timer value of the T304 timer (i.e., T304 timer value) for the target cell may be included in theReconfigurationWithSyncinRRCReconfigurationfor the target cell.

[0134] While the timer is running, the UE may perform DL synchronization and / or UL synchronization (e.g., random access) towards the target cell. The UE may skip the random access towards the target cell if timing advance (TA) information for the target cell is available.

[0135] In step S807, the UE, serving BS and / or BS related to the target cell may perform actions related to conditional mobility completion. For example, upon successful completion of the random access on the corresponding target cell, the UE may stop the timer (e.g., T304 timer).

[0136] Further, there may be another type of mobility called L1 / L2-triggered mobility (LTM). LTM is a procedure in which a gNB receives L1 measurement report(s) from a UE, and on their basis the gNB changes UE's serving cell by a cell switch command signalled via a MAC CE. The cell switch command indicates an LTM candidate cell configuration that the gNB previously prepared and provided to the UE through RRC signalling. Then the UE switches to the target cell according to the cell switch command. The LTM procedure can be used to reduce the mobility latency.

[0137] When configured by the network, it is possible to activate TCI states of one or multiple cells that are different from the current serving cell. For instance, the TCI states of the LTM candidate cells can be activated in advance before any of those cells become the serving cell. This allows the UE to be DL synchronized with those cells, thereby facilitating a faster cell switch to one of those cells when cell switch is triggered.

[0138] When configured by the network, it is possible to initiate UL TA acquisition procedure to one or multiple cells that are different from the current serving cell. For instance, the network may request the UE to perform early TA acquisition of a candidate cell before a cell switch. The early TA acquisition is triggered by PDCCH order or realized through UE-based TA measurement. In the former case, the gNB to which the candidate cell belongs calculates the TA value and sends it to the gNB to which the serving cell belongs. The serving cell sends the TA value in the LTM cell switch command MAC CE when triggering LTM cell switch. In the latter case, the UE applies the TA value measured by itself and performs RACH-less LTM upon receiving the cell switch command.

[0139] If UE-based TA measurement is configured, UE performs RACH-less LTM upon receiving the cell switch command. Otherwise, UE determines whether to access the target cell with the RA procedure depending on whether a TA value is provided in the cell switch command. For RACH-less LTM, the UE accesses the target cell via a configured grant provided in the LTM candidate cell configuration and selects the configured grant occasion associated with the beam indicated in the cell switch command. [If the LTM candidate cell configuration does not include a configured grant, the UE monitors PDCCH for dynamic scheduling from the target cell upon LTM cell switch.] Before RACH-less LTM procedure completion, the UE shall not trigger random access procedure if it does not have a valid PUCCH resource for triggered SRs.

[0140] The following principles apply to LTM:

[0141] - The UE doesn't update its security key after an intra-gNB LTM cell switch.

[0142] - Subsequent LTM is supported.

[0143] LTM supports both intra-gNB-DU and intra-gNB-CU inter-gNB-DU mobility. LTM supports both intra-frequency and inter-frequency mobility, including mobility to inter-frequency cell that is not a current serving cell. The following scenarios are supported:

[0144] - PCell change in non-CA scenario and non-DC scenario,

[0145] - PCell change in CA scenario,

[0146] - Dual connectivity scenario, MCG PCell change and SCG PSCell change without MN involvement case (i.e., intra-SN PSCell change).

[0147] While the UE has stored LTM candidate cell configurations the UE can also execute any L3 handover command sent by the network. It is up to the network to avoid any issue due to a collision between LTM execution and L3 handover execution, e.g., avoiding sending LTM cell switch command and L3 handover command simultaneously.

[0148] Cell switch command is conveyed in a MAC CE, which contains the necessary information to perform the LTM cell switch.

[0149] The overall procedure for LTM is shown in FIG. 9 below. Subsequent LTM is done by repeating the early synchronization, LTM cell switch execution, and LTM cell switch completion steps without releasing other LTM candidate cell configurations after each LTM cell switch completion.

[0150] FIG. 9 shows an example of a signaling procedure for LTM according to an embodiment of the present disclosure.

[0151] Referring to FIG. 9, in step S901, The UE sends aMeasurementReportmessage to the gNB.

[0152] In step S903, the gNB decides to configure LTM and initiates candidate cell(s) preparation.

[0153] In step S905, the gNB transmits anRRCReconfigurationmessage to the UE including the LTM candidate cell configurations of one or multiple candidate cells. TheRRCReconfigurationmessage comprise an LTM configuration / cell switch configuration (e.g.,LTM-Config) comprising a list of LTM candidate configurations. That is, the network configures the UE with one or more LTM candidate configurations within theLTM-ConfigIE. The UE stores the LTM configuration / cell switch configuration comprising the list of LTM candidate configurations.

[0154] In NR-DC, the UE may receive two independentltm-Config:

[0155] - anltm-Configassociated with the MCG that is included within anRRCReconfigurationmessage received via SRB1; and

[0156] - anltm-Configassociated with the SCG that is included within anRRCReconfigurationmessage either received via SRB3, or, alternatively, embedded in anRRCReconfigurationmessage received via SRB1.

[0157] In this case (i.e., when the UE received two independentltm-Config):

[0158] - the UE maintains two independentVarLTM-Config, one associated with eachltm-Config;

[0159] - the UE maintains two independentVarLTM-ServingCellNoResetID, one associated with eachltm-Config;

[0160] - the UE maintains two independentVarLTM-ServingCellUE-MeasuredTA-ID, one associated with eachltm-Config; and / or

[0161] - the UE independently performs all the procedures for eachltm-Configand the associatedVarLTM-Config, unless explicitly stated otherwise.

[0162] TheLTM-Configmay comprise at least one of:

[0163] -ltm-ReferenceConfiguration: LTM reference configuration used to provide a configuration that is common, within the same cell group, to all configured non-complete LTM candidate configurations;

[0164] -ltm-CandidateToAddModList: a list of LTM candidate configurations (e.g.,LTM-Candidate(s));

[0165] -ltm-CandidateToReleaseList: a list of LTM candidate configuration IDs (e.g.,LTM-CandidateId(s)) related to LTM candidate configurations to remove;

[0166] -ltm-ServingCellNoResetID: serving cell ID based on which the UE determines whether a L2 reset is needed or not upon an LTM cell switch procedure; or

[0167] -ltm-ServingCellUE-MeasuredTA-ID: serving cell ID based on which the UE determines whether UE-based TA measurements are needed or not.

[0168] TheLTM-Candidate(i.e., LTM candidate configuration / candidate configuration / candidate cell configuration) may be related to a candidate (target) cell, and comprise at least one of:

[0169] -ltm-CandidateId: an ID used to identify an LTM candidate configuration;

[0170] -ltm-CandidateConfig: a configuration of the related candidate cell for LTM, comprisingRRCReconfigurationmessage to be applied when LTM / cell switch is executed;

[0171] -ltm-ConfigComplete: if included in theLTM-Candidate, the UE may consider that the relatedltm-CandidateConfigis a complete configuration of the related candidate cell for LTM;

[0172] -ltm-NoResetID: if this field is equal toltm-ServingCellNoResetID, UE may determine that L2 reset is needed upon an LTM cell switch procedure; or

[0173] -ltm-UE-MeasuredTA-ID: if this field is equal toltm-ServingCellNoResetID, UE may determine that the UE-based TA measurements are needed.

[0174] The UE shall perform the following actions based on the receivedLTM-ConfigIE:

[0175] 1> if the receivedLTM-Configincludesltm-ReferenceConfiguration:

[0176] 2> if the currentVarLTM-Configincludes anltm-ReferenceConfiguration:

[0177] 3> replace theltm-ReferenceConfigurationvalue withinVarLTM-Configwith the receivedltm-ReferenceConfiguration;

[0178] 2> else:

[0179] 3> store the receivedltm-ReferenceConfigurationinVarLTM-Config.

[0180] 1> if the receivedLTM-Configincludesltm-ServingCellNoResetID:

[0181] 2> if the currentVarLTM-ServingCellNoResetIDincludes anltm-ServingCellNoResetID:

[0182] 3> replace theltm-ServingCellNoResetIDvalue withinVarLTM-ServingCellNoResetIDwith the receivedltm-ServingCellNoResetID;

[0183] 2> else:

[0184] 3> store the receivedltm-ServingCellNoResetIDinVarLTM-ServingCellNoResetID;

[0185] 1> if the receivedLTM-Configincludesltm-ServingCellUE-MeasuredTA-ID:

[0186] 2> if the currentVarLTM-ServingCellUE-MeasuredTA-IDincludes anltm-ServingCellUE-MeasuredTA-ID:

[0187] 3> replace theltm-ServingCellUE-MeasuredTA-IDvalue withinVarLTM-ServingCellUE-MeasuredTA-IDwith the receivedltm-ServingCellUE-MeasuredTA-ID;

[0188] 2> else:

[0189] 3> store the receivedltm-ServingCellUE-MeasuredTA-IDinVarLTM-ServingCellUE-MeasuredTA-ID;

[0190] 1> if theLTM-Configincludes theltm-CandidateToAddModList:

[0191] 2> perform the LTM candidate cell addition or reconfiguration;

[0192] 1> else if theLTM-Configincludes theltm-CandidateToReleaseList:

[0193] 2> perform the LTM candidate cell release.

[0194] To perform the LTM candidate cell release, the UE shall:

[0195] 1> for eachltm-CandidateIdvalue included in theltm-CandidateToReleaseList:

[0196] 2> if the currentVarLTM-Configincludes anLTM-Candidateassociated with theltm-CandidateIdvalue:

[0197] 3> remove the entry related toLTM-CandidatefromVarLTM-Config;

[0198] To perform the LTM candidate cell addition and / or modification, the UE shall:

[0199] 1> for eachltm-CandidateIdvaluein theltm-CandidateToAddModList:

[0200] 2> if the currentVarLTM-Configincludes anLTM-Candidatewith theltm-CandidateIdvalue:

[0201] 3> replace theLTM-CandidatewithinVarLTM-Configin accordance with the receivedLTM-Candidate;

[0202] 2> else:

[0203] 3> add the receivedLTM-CandidatetoVarLTM-Config.

[0204] 2> generate a complete LTM configuration.

[0205] The generation of the complete LTM configuration is a procedure for the UE to generate a complete configuration for LTM to be stored upon it is generated and applied only when an indication of an LTM cell switch is received by lower layers. During the generation of the complete configuration for LTM, the UE shall not modify its current configuration.

[0206] To generate the complete LTM configuration, the UE shall:

[0207] 1> if theLTM-Candidateincludesltm-ConfigComplete:

[0208] 2> consider that the relatedltm-CandidateConfigin theLTM-Candidateis a complete configuration for LTM;

[0209] 1> else:

[0210] 2> generate a complete configuration for LTM, by applying the relatedltm-CandidateConfigon top ofltm-referenceConfiguration.

[0211] 2> consider the configuration inltm-referenceConfigurationas the complete configuration for LTM.

[0212] In some implementations, the UE may postpone the generation of a complete LTM configuration until the executing of an LTM cell switch.

[0213] In step S907, the UE transmits anRRCReconfigurationCompletemessage to the gNB.

[0214] In some implementations, the UE performs DL synchronization with the LTM candidate cell(s) before receiving the cell switch command.

[0215] In some implementations, the UE may perform UL synchronization with LTM candidate cell(s) before receiving the cell switch command, by using UE-based TA measurement, if configured, and / or by transmitting a preamble towards the candidate cell, as triggered by the gNB. When UE-based TA measurement is configured, UE acquires the TA value(s) of the candidate cell(s) by measurement. Otherwise, UE performs early TA acquisition with the candidate cell(s) as requested by the network before receiving the cell switch command. This is done via CFRA triggered by a PDCCH order from the source cell, following which the UE sends preamble towards the indicated candidate cell. In order to minimize the data interruption of the source cell due to CFRA towards the candidate cell(s), the UE doesn't receive random access response from the network for the purpose of TA value acquisition and the TA value of the candidate cell is indicated in the cell switch command. The UE doesn't maintain the TA timer for the candidate cell and relies on network implementation to guarantee the TA validity.

[0216] In step S909, the UE performs L1 measurements on the configured LTM candidate cell(s) and transmits L1 measurement reports to the gNB. L1 measurement should be performed as long as RRC reconfiguration (i.e.,RRCReconfiguration) is applicable.

[0217] In step S911, the gNB decides to execute cell switch to a target cell.

[0218] In step S913, the gNB transmits an LTM cell switch command MAC CE triggering cell switch by including a target configuration ID which indicates the index of the candidate configuration of the target cell (corresponds toltm-CandidateId), a beam indicated with a TCI state or beams indicated with DL and UL TCI states, and a timing advance command for the target cell, if available. The UE switches to the target cell and applies a configuration of the target cell for LTM (i.e.,ltm-CandidateConfig) indicated by the target configuration ID.

[0219] Upon the indication by lower layers that an LTM cell switch procedure is triggered (e.g., upon receiving the LTM cell switch command MAC CE), the UE shall:

[0220] 1> use the default values specified in 9.2.3 for timers T310, T311 and constants N310, N311 associate to cell group for which the LTM cell switch procedure is triggered;

[0221] 1> apply the default L1 parameter values as specified in corresponding physical layer specifications;

[0222] 1> if the value of fieldltm-NoResetIDcontained within theLTM-Candidate IEinVarLTM-Configindicated by lower layers or for the selected cell in accordance with 5.3.7.3 is equal to the value ofltm-ServingCellNoResetIDwithinVarLTM-ServingCellNoResetID:

[0223] 2> continue using the current RLC entity in the LTM candidate configuration indicated by lower layers;

[0224] 1> else:

[0225] 2> for eachlogicalChannelIdandlogicalChannelIdExtthat is part of the current UE configuration for the cell group for which the LTM cell switch procedure is triggered:

[0226] 3> re-establish the corresponding RLC entity;

[0227] 2> for eachdrb-Identityvalue that is part of the current UE configuration:

[0228] 3> trigger the PDCP entity of this DRB to perform data recovery;

[0229] 2> replace the value ofltm-ServingCellNoResetIDinVarLTM-ServingCellNoResetIDwith the value ofltm-NoResetIDin theLTM-CandidateinVarLTM-Configindicated by lower layers or for the selected cell;

[0230] 1> if the value ofltm-UE-MeasuredTA-IDcontained within theLTM-Candidate IEinVarLTM-Configindicated by lower layers or for the selected cell is equal to the value ofltm-ServingCellUE-MeasuredTA-IDwithinVarLTM-ServingCellUE-MeasuredTA-ID:

[0231] 2> inform lower layers that UE should perform UE-based TA measurements;

[0232] 2> replace the value ofltm-ServingCellUE-MeasuredTA-IDinVarLTM-ServingCellUE-MeasuredTA-IDwith the value received withinltm-UE-MeasuredTA-ID;

[0233] 1> else:

[0234] 2> replace the value ofltm-ServingCellUE-MeasuredTA-IDinVarLTM-ServingCellUE-MeasuredTA-IDwith the value ofltm-UE-MeasuredTA-IDin theLTM-CandidateinVarLTM-Configindicated by lower layers or for the selected cell;

[0235] In some implementations, the UE performs the UE-based TA measurements upon execution and / or configuration.

[0236] 1> continue using the current PDCP entity in the LTM candidate configuration indicated by lower layers;

[0237] 1> ifltm-ConfigCompleteis not included within theLTM-Candidate IEinVarLTM-Configindicated by lower layers or for the selected cell:

[0238] 2> considerltm-ReferenceConfigurationinVarLTM-Config, associated with the cell group for which the LTM cell switch procedure is triggered, to be the current UE configuration;

[0239] When the UE considers the reference configuration to be the current UE configuration, the UE should store fields and configurations that are part of the reference configuration but should not execute any actions or procedures triggered by the reception of anRRCReconfigurationmessage.

[0240] 1> if the LTM cell switch is triggered by an indication from lower layers:

[0241] 2> apply the LTM configuration inltm-CandidateConfigwithinLTM-Candidate IEinVarLTM-Configidentified by the LTM candidate configuration identity as received from lower layers (i.e.,ltm-CandidateIdindicated by the cell switch command).

[0242] 1> consider the LTM candidate cell indicated by lower layers to be the serving cell;

[0243] Whenltm-ConfigCompleteis not included for an LTM candidate configuration, before an LTM cell switch is triggered, the UE may generate and store an RRC reconfiguration message by applying the received LTM candidate configuration on top of the LTM reference configuration, and the stored RRC reconfiguration message is applied when the LTM cell switch is triggered.

[0244] In step S915, UE may detach from the source cell, and apply the target cell configuration(s).

[0245] In some implementations, the UE performs the random access procedure towards the target cell, if UE does not have valid TA of the target cell. For example, the UE performs contention-free random access (CFRA) if the LTM cell switch command MAC CE contains information for CFRA. If UE has valid TA of the target cell, the UE may skip the random access procedure towards the target cell (i.e., RACH-less LTM).

[0246] In step S917, the UE completes the LTM cell switch procedure by sendingRRCReconfigurationCompletemessage to target cell. If the UE has performed a RA procedure, the UE considers that LTM cell switch execution is successfully completed when the random access procedure is successfully completed. For RACH-less LTM, the UE considers that LTM cell switch execution is successfully completed when the UE determines that the network has successfully received its first UL data. The UE determines successful reception of its first UL data by receiving a PDCCH addressing the UE's C-RNTI in the target cell, which schedules a new transmission following the first UL data. The PDCCH carries either a DL assignment or an UL grant addressing the same HARQ process as the first UL data.

[0247] To complete the LTM cell switch procedure, the UE shall:

[0248] 1> if theRRCReconfigurationmessage including theLTM-Candidate IErelated to the LTM candidate configuration identity as received by lower layers was received via SRB1 within thenr-SCGwithinmrdc-SecondaryCellGroup(UE in NR-DC):

[0249] 2> submit theRRCReconfigurationCompletemessage via the NR MCG embedded in NR RRC messageULInformationTransferMRDC;

[0250] 1> else ifRRCReconfigurationmessage including theLTM-Candidate IErelated to the LTM candidate configuration identity as received by lower layers was received via SRB3 (UE in NR-DC):

[0251] 2> submit theRRCReconfigurationCompletemessage via SRB3 to lower layers for transmission using the new configuration;

[0252] 1> else (RRCReconfigurationwas received via SRB1):

[0253] 2> submit theRRCReconfigurationCompletemessage to lower layers for transmission via SRB1 using the new configuration.

[0254] Hereinafter, RRC (connection) re-establishment procedure is described.

[0255] The purpose of the RRC (connection) re-establishment procedure is to re-establish the RRC connection. A UE in RRC_CONNECTED, for which AS security has been activated with SRB2 and at least one DRB / multicast MRB setup or, for IAB and NCR, SRB2, may initiate the procedure in order to continue the RRC connection. The connection re-establishment succeeds if the network is able to find and verify a valid UE context or, if the UE context cannot be retrieved, and the network responds with anRRCSetup.

[0256] The network applies the RRC (connection) re-establishment procedure e.g., as follows:

[0257] - When AS security has been activated and the network retrieves or verifies the UE context:

[0258] - to re-activate AS security without changing algorithms;

[0259] - to re-establish and resume the SRB1;

[0260] - When UE is re-establishing an RRC connection, and the network is not able to retrieve or verify the UE context:

[0261] - to discard the stored AS Context and release all RBs and BH RLC channels and Uu Relay RLC channels;

[0262] - to fallback to establish a new RRC connection.

[0263] If AS security has not been activated, the UE shall not initiate the procedure but instead moves to RRC_IDLE directly, with release cause 'other'. If AS security has been activated, but SRB2 and at least one DRB or multicast MRB or, for IAB and NCR, SRB2, are not setup, the UE does not initiate the procedure but instead moves to RRC_IDLE directly, with release cause 'RRC connection failure'.

[0264] The RRC connection re-establishment procedure may be performed for a failure recovery. The failure recovery procedure is illustrated in FIG. 10.

[0265] FIG. 10 shows an example of a failure recovery procedure according to an embodiment of the present disclosure.

[0266] Referring to FIG. 10, in step S1001, UE may detect a failure.

[0267] In step S1003, the UE may initiate an RRC connection re-establishment procedure based on / upon detecting the failure. For example, the UE may initiate the RRC connection re-establishment procedure when at least one of the following conditions is met:

[0268] - upon detecting radio link failure of the MCG andt316is not configured; or

[0269] - upon detecting radio link failure of the MCG while SCG transmission is suspended; or

[0270] - upon detecting radio link failure of the MCG while PSCell change or PSCell addition is ongoing; or

[0271] - upon detecting radio link failure of the MCG while the SCG is deactivated; or

[0272] - upon re-configuration with sync failure of the MCG; or

[0273] - upon mobility from NR failure; or

[0274] - upon integrity check failure indication from lower layers concerning SRB1 or SRB2, except if the integrity check failure is detected on theRRCReestablishmentmessage; or

[0275] - upon an RRC connection reconfiguration failure; or

[0276] - upon detecting radio link failure for the SCG while MCG transmission is suspended in NR-DC or in NE-DC; or

[0277] - upon reconfiguration with sync failure of the SCG while MCG transmission is suspended; or

[0278] - upon SCG change failure while MCG transmission; or

[0279] - upon SCG configuration failure while MCG transmission is suspended in NR-DC or in NE-DC; or

[0280] - upon integrity check failure indication from SCG lower layers concerning SRB3 while MCG is suspended; or

[0281] - upon T316 expiry.

[0282] In step S1005, the UE may perform a cell selection based on / upon initiating the RRC connection re-establishment procedure.

[0283] In step S1007, the UE may determine whether a fast recovery condition is satisfied based on / upon selecting a suitable cell.

[0284] The fast recovery condition may comprise at least one of a condition for a fast recovery with performing CHO, or a condition for a fast recovery with performing LTM.

[0285] For example, the condition for a fast recovery with performing CHO may be satisfied if:

[0286] - the cell selection is triggered by detecting radio link failure of the MCG or re-configuration with sync failure of the MCG, except for an LTM cell switch procedure following cell selection performed while timer T311 was running, or mobility from NR failure; and

[0287] -attemptCondReconfigis configured; and

[0288] - the selected cell is not configured withCondEventT1, or the selected cell is configured withCondEventT1leaving condition has not been fulfilled; and

[0289] - the selected cell is one of the candidate cells for which thereconfigurationWithSyncis included in themasterCellGroupin the MCGVarConditionalReconfigand thecondExecutionCondPSCellis not configured for the correspondingcondReconfigIdin the MCGVarConditionalReconfig(i.e., the selected cell is one of the CHO candidate cells).

[0290] For example, the condition for a fast recovery with performing LTM may be satisfied if:

[0291] - the cell selection is triggered by detecting radio link failure of the MCG or re-configuration with sync failure of the MCG for an LTM cell switch procedure triggered upon the indication by lower layers; and

[0292] -attemptLTM-Switchis configured; and

[0293] - the selected cell is one of the LTM candidate cells in theLTM-CandidateIE withinltm-Configassociated with the MCG.

[0294] If the fast recovery condition is satisfied, in step S1009, the UE may perform a fast recovery based on the selected cell.

[0295] For example, if the condition for a fast recovery with performing CHO may be satisfied, the UE may perform a CHO to the selected cell, and / or apply the storedcondRRCReconfig / RRCReconfigurationassociated to the selected cell (i.e., apply configuration of the selected cell for CHO).

[0296] For example, if the condition for a fast recovery with performing LTM may be satisfied, the UE may perform an LTM to the selected cell, and / or apply theRRCReconfigurationmessage inltm-CandidateConfigwithinLTM-CandidateIE inltm-Configrelated to the LTM candidate configuration identity for the selected cell (i.e., apply configuration of the selected cell for LTM).

[0297] If both of the condition for a fast recovery with performing CHO and the condition for a fast recovery with performing LTM are satisfied, the UE may perform either a CHO to the selected cell, or an LTM to the selected cell.

[0298] If the fast recovery condition is not satisfied, in step S1011, the UE may transmit anRRCReestablishmentRequestmessage to the selected cell.

[0299] The UE shall set the contents ofRRCReestablishmentRequestmessage as follows:

[0300] 1> if the RRC connection re-establishment procedure was initiated due to radio link failure or reconfiguration with sync failure; or

[0301] 1> if the RRC connection re-establishment procedure was initiated due to mobility from NR failure and ifvoiceFallbackIndicationis included in theMobilityFromNRCommandmessage:

[0302] 2> set thereestablishmentCellIdin theVarRLF-Reportto the global cell identity of the selected cell;

[0303] 1> set theue-Identityas follows:

[0304] 2> set thec-RNTIto the C-RNTI used in the source PCell (reconfiguration with sync or mobility from NR failure) or used in the PCell in which the trigger for the re-establishment occurred (other cases);

[0305] 2> set thephysCellIdto the physical cell identity of the source PCell (reconfiguration with sync or mobility from NR failure) or of the PCell in which the trigger for the re-establishment occurred (other cases);

[0306] 2> set theshortMAC-Ito the 16 least significant bits of the MAC-I calculated:

[0307] 3> over the ASN.1 encoded as per clause 8 (i.e., a multiple of 8 bits)VarShortMAC-Input;

[0308] 3> with the KRRCint key and integrity protection algorithm that was used in the source PCell (reconfiguration

[0309] with sync or mobility from NR failure) or of the PCell in which the trigger for the re-establishment

[0310] occurred (other cases); and

[0311] 3> with all input bits for COUNT, BEARER and DIRECTION set to binary ones;

[0312] 1> set thereestablishmentCauseas follows:

[0313] 2> if the re-establishment procedure was initiated due to reconfiguration failure:

[0314] 3> set thereestablishmentCauseto the valuereconfigurationFailure;

[0315] 2> else if the re-establishment procedure was initiated due to reconfiguration with sync failure (intra-NR handover failure or inter-RAT mobility from NR failure):

[0316] 3> set thereestablishmentCauseto the valuehandoverFailure;

[0317] 2> else:

[0318] 3> set thereestablishmentCauseto the valueotherFailure;

[0319] 1> re-establish PDCP for SRB1;

[0320] 1> if the UE is acting as L2 U2N Remote UE:

[0321] 2> establish or re-establish (e.g. via release and add) SL RLC entity for SRB1;

[0322] 2> apply the default configuration of SL-RLC1 for SRB1;

[0323] 2> apply the default configuration of PDCP for SRB1;

[0324] 2> apply the default configuration of SRAP for SRB1;

[0325] 1> else:

[0326] 2> re-establish RLC for SRB1;

[0327] 2> apply the default configuration defined in 9.2.1 for SRB1;

[0328] 1> configure lower layers to suspend integrity protection and ciphering for SRB1;

[0329] Ciphering is not applied for the subsequentRRCReestablishmentmessage used to resume the connection.

[0330] An integrity check is performed by lower layers, but merely upon request from RRC.

[0331] 1> resume SRB1;

[0332] 1> ifta-Reportorta-ReportATGis configured with valueenabledand the UE supports TA reporting:

[0333] 2> indicate TA report initiation to lower layers;

[0334] 1> submit theRRCReestablishmentRequestmessage to lower layers for transmission.

[0335] Upon reception ofRRCReestablishmentmessage by the UE after transmitting theRRCReestablishmentRequestmessage, the UE shall:

[0336] 1> stop timer T301;

[0337] 1> consider the current cell to be the PCell;

[0338] 1> update the KgNB key based on the current KgNB key or the NH,using the receivednextHopChainingCountvalue;

[0339] 1> store thenextHopChainingCountvalue indicated in theRRCReestablishmentmessage;

[0340] 1> derive the KRRCenc and KUPenc keys associated with the previously configuredcipheringAlgorithm;

[0341] 1> derive the KRRCint and KUPint keys associated with the previously configuredintegrityProtAlgorithm.

[0342] 1> request lower layers to verify the integrity protection of theRRCReestablishmentmessage, using the previously configured algorithm and the KRRCint key;

[0343] 1> if the integrity protection check of theRRCReestablishmentmessage fails:

[0344] 2> perform the actions upon going to RRC_IDLE as specified in 5.3.11, with release cause 'RRC connection failure', upon which the procedure ends;

[0345] 1> configure lower layers to resume integrity protection for SRB1 using the previously configured algorithm and the KRRCint key immediately, i.e., integrity protection shall be applied to all subsequent messages received and sent by the UE, including the message used to indicate the successful completion of the procedure;

[0346] 1> configure lower layers to resume ciphering for SRB1 using the previously configured algorithm and, the KRRCenc key immediately, i.e., ciphering shall be applied to all subsequent messages received and sent by the UE, including the message used to indicate the successful completion of the procedure;

[0347] 1> release the measurement gap configuration indicated by themeasGapConfig, if configured;

[0348] 1> release the MUSIM gap configuration indicated by themusim-GapConfig, if configured;

[0349] 1> release the FR2 UL gap configuration indicated by theul-GapFR2-Config, if configured;

[0350] 1> perform the L2 U2N Remote UE configuration procedure in accordance with the receivedsl-L2RemoteUE-Config;

[0351] 1> for each application layer measurement configuration withappLayerIdleInactiveConfigconfigured:

[0352] 2> if the RPLMN is not included inplmn-IdentityListinVarAppLayerPLMN-ListConfig:

[0353] 3> discard any application layer measurement reports which were not yet fully submitted to lower layers for transmission;

[0354] 3> forward themeasConfigAppLayerIdand inform upper layers about the release of the application layer measurement configuration;

[0355] 3> release the application layer measurement configuration including its fields in the UE variablesVarAppLayerIdleConfigandVarAppLayerPLMN-ListConfig;

[0356] 3> consider itself not to be configured to send application layer measurement reports for themeasConfigAppLayerId;

[0357] 1> set the content ofRRCReestablishmentCompletemessage as follows:

[0358] 2> if the UE has logged measurements available for NR and if the RPLMN is included inplmn-IdentityListstored inVarLogMeasReport; or

[0359] 2> if the UE has logged measurements available for NR and if the current registered SNPN identity is included insnpn-ConfigID-Liststored inVarLogMeasReport:

[0360] 3> include thelogMeasAvailablein theRRCReestablishmentCompletemessage;

[0361] 3> if Bluetooth measurement results are included in the logged measurements the UE has available for NR:

[0362] 4> include thelogMeasAvailableBTin theRRCReestablishmentCompletemessage;

[0363] 3> if WLAN measurement results are included in the logged measurements the UE has available for NR:

[0364] 4> include thelogMeasAvailableWLANin theRRCReestablishmentCompletemessage;

[0365] 2> if thesigLoggedMeasTypeinVarLogMeasReportis included; or

[0366] 2> if the UE supports the override protection of the signalling based logged MDT for inter-RAT (i.e. LTE to NR), and if thesigLoggedMeasTypeinVarLogMeasReportis included:

[0367] 3> if T330 timer is running (associated to the logged measurement configuration for NR or for LTE):

[0368] 4> setsigLogMeasConfigAvailabletotruein theRRCReestablishmentCompletemessage;

[0369] 3> else:

[0370] 4> if the UE has logged measurements inVarLogMeasReportor inVarLogMeasReport:

[0371] 5> setsigLogMeasConfigAvailabletofalsein theRRCReestablishmentCompletemessage;

[0372] 2> if the UE has connection establishment failure or connection resume failure information available inVarConnEstFailReportorVarConnEstFailReportListand if the RPLMN is equal toplmn-Identitystored inVarConnEstFailReportorin at least one of the entries ofVarConnEstFailReportList; or

[0373] 2> if the UE supports multiple CEF report and if the UE has connection establishment failure information or connection resume failure information available inVarConnEstFailReportorVarConnEstFailReportListand if the registered SNPN identity is equal tosnpn-IdentityinnetworkIdentitystored inVarConnEstFailReportor any entry ofVarConnEstFailReportList:

[0374] 3> includeconnEstFailInfoAvailablein theRRCReestablishmentCompletemessage;

[0375] 2> if the UE has radio link failure or handover failure information available inVarRLF-Reportand if the RPLMN is included inplmn-IdentityListstored inVarRLF-Report; or

[0376] 2> if the UE has radio link failure or handover failure information available inVarRLF-Reportand if the UE is capable of cross-RAT RLF reporting and if the RPLMN is included inplmn-IdentityListstored inVarRLF-Report; or

[0377] 2> if the UE has radio link failure or handover failure information available inVarRLF-Reportand if the current registered SNPN identity is included insnpn-IdentityListstored inVarRLF-Report:

[0378] 3> includerlf-InfoAvailablein theRRCReestablishmentCompletemessage;

[0379] 2> if the UE has successful handover information available inVarSuccessHO-Reportand if the RPLMN is included inplmn-IdentityListstored inVarSuccessHO-Report; or

[0380] 2> if the UE has successful handover information available inVarSuccessHO-Reportand if the current registered SNPN identity is included insnpn-IdentityListstored in theVarSuccessHO-Report:

[0381] 3> includesuccessHO-InfoAvailablein theRRCReestablishmentCompletemessage;

[0382] 2> if the UE has successful PSCell change or addition information available inVarSuccessPSCell-Reportand if the RPLMN is included inplmn-IdentityListstored inVarSuccessPSCell-Report; or

[0383] 2> if the UE has successful PSCell change or addition information available inVarSuccessPSCell-Reportand if the current registered SNPN identity is included insnpn-IdentityListstored in theVarSuccessPSCell-Report:

[0384] 3> includesuccessPSCell-InfoAvailablein theRRCReestablishmentCompletemessage;

[0385] 2> if the UE has flight path information available:

[0386] 3> includeflightPathInfoAvailable;

[0387] 2> if the UE has at least one stored application layer measurement configuration withappLayerIdleInactiveConfigconfigured which has not been successfully transmitted since entering RRC_CONNECTED state:

[0388] 3> includemeasConfigReportAppLayerAvailablein theRRCReestablishmentCompletemessage;

[0389] 2> ifSIB1containsmusim-CapRestrictionAllowed:

[0390] 3> if supported, include themusim-CapRestrictionIndin theRRCReestablishmentCompletemessage upon determining it has temporary capability restriction;

[0391] Upon reception ofmusim-CapRestrictionIndinRRCReestablishmentComplete, it is up to network implementation to configure the UE with a limited configuration that is used until network sends / RRCReconfigurationbased on the actual restricted UE capabilities included inUEAssistanceInformation.

[0392] 1> submit theRRCReestablishmentCompletemessage to lower layers for transmission;

[0393] 1> ifSIB21is provided by the PCell; or

[0394] 1> ifnonServingCellMIIis provided inSIB1by the PCell:

[0395] 2> if the UE initiated transmission of anMBSInterestIndicationmessage during the last 1 second preceding detection of radio link failure:

[0396] 3> initiate transmission of anMBSInterestIndicationmessage;

[0397] 1> the procedure ends.

[0398] Upon T311 expiry, the UE shall:

[0399] 1> if the procedure was initiated due to radio link failure or handover failure:

[0400] 2> set thenoSuitableCellFoundin theVarRLF-Reporttotrue;

[0401] 1> perform the actions upon going to RRC_IDLE, with release cause 'RRC connection failure'.

[0402] Upon reception of theRRCSetupmessage by the UE after transmitting theRRCReestablishmentRequestmessage, the UE shall perform the RRC connection establishment procedure.

[0403] Meanwhile, UE may initiate RRC re-establishment procedure when a failure condition occurs (e.g., radio link failure, handover failure, reconfiguration failure). If the UE initiates the RRC re-establishment procedure, it causes not only a large interruption but also unnecessary reconfiguration after the re-establishment. For a fast recovery, UE may utilize configured candidate cells (e.g., candidate cell for which either CHO or LTM is configured for MCG, and / or candidate cell for which either CPAC or LTM is configured for SCG). For example, upon failure, UE may perform CHO or LTM if the selected cell for RRC re-establishment is configured with CHO or LTM. In this case, if the selected cell is configured with both CHO and LTM, UE may perform either LTM or CHO to the selected cell.

[0404] In the present disclosure, a fast recovery with performing CHO is called as CHO-based (failure) recovery and a fast recovery with performing LTM is called as LTM-based (failure) recovery.

[0405] When the LTM-based recovery is performed, UE may keep the stored candidate configuration(s) for CHO. In this case, UE may perform CHO to a cell (which may be the target cell of the LTM-based recovery) after the LTM-based recovery is failed if the cell is configured with both CHO and LTM. CHO-based recovery after the failure of the LTM-based recovery may lead to an increase of data interruption because the candidate configuration(s) for CHO may be invalid upon CHO-based recovery.

[0406] Therefore, the present disclosure provides various embodiments for handling candidate configurations for CHO when performing LTM-based recovery.

[0407] FIG. 11 shows an example of a method performed by a UE according to an embodiment of the present disclosure.

[0408] Referring to FIG. 11, in step S1101, the UE may receive one or more candidate configurations for conditional mobility and one or more candidate configurations for cell switch. Each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch may be related to a corresponding candidate cell.

[0409] In step S1103, the UE may detect a failure. The failure may comprise at least one of an RLF of an MCG, or a failure of an MCG cell switch triggered by a cell switch command received from a network.

[0410] In step S1105, the UE may perform a first cell selection based on detecting the failure.

[0411] In step S1107, based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, the UE may perform a cell switch execution to the candidate cell.

[0412] In step S1109, the UE may remove the one or more candidate configurations for conditional mobility based on performing the cell switch execution.

[0413] According to various embodiments, after receiving the one or more candidate configurations for conditional mobility, the UE may store the received one or more candidate configurations for conditional mobility in a list of candidate configurations for conditional mobility. The UE may remove all candidate configurations for conditional mobility in the list of candidate configurations for conditional mobility.

[0414] According to various embodiments, the UE may remove the one or more candidate configurations for cell switch based on performing the cell switch execution.

[0415] According to various embodiments, after receiving the one or more candidate configurations for cell switch, the UE may store the received one or more candidate configurations for cell switch in a list of candidate configurations for cell switch. The UE may remove all candidate configurations for cell switch in the list of candidate configurations for cell switch.

[0416] According to various embodiments, to perform the cell switch execution to the candidate cell, the UE may apply a radio resource control (RRC) reconfiguration in the candidate configuration for cell switch related to the candidate cell. The UE may remove the one or more candidate configurations for conditional mobility based on applying the candidate configuration for cell switch.

[0417] According to various embodiments, the candidate cell selected by the first cell selection may be related to both of the candidate configuration for cell switch and a candidate configuration for conditional mobility. The UE may remove the candidate configuration for conditional mobility related to the candidate cell based on performing the cell switch execution to the candidate cell.

[0418] According to various embodiments, the cell switch execution may be performed based on a cell switch attempt configuration (e.g.,attemptLTM-Switch) being configured.

[0419] According to various embodiments, the UE may detect a failure of the cell switch execution. The UE may perform a second cell selection based on detecting the failure of the cell switch execution. The UE may transmit an RRC re-establishment request message to a cell selected by the second cell selection.

[0420] According to various embodiments, the RRC re-establishment request message may be transmitted to the cell selected by the second cell selection, based on the cell selected by the second cell selection being a candidate cell related to the one or more candidate configurations for conditional mobility that had been removed before.

[0421] According to various embodiments, the RRC re-establishment request message may be transmitted to the cell selected by the second cell selection, based on a conditional mobility attempt configuration (e.g.,attemptCondReconfig) being configured.

[0422] According to various embodiments, the cell switch execution may comprise an LTM execution.

[0423] FIG. 12 shows an example of a signal flow between a UE and a network node according to an embodiment of the present disclosure.

[0424] Referring to FIG. 12, in step S1201, the network node may transmit, to the UE, one or more candidate configurations for conditional mobility and one or more candidate configurations for cell switch. Each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch may be related to a corresponding candidate cell.

[0425] In step S1203, the UE may detect a failure. The failure may comprise at least one of an RLF of an MCG, or a failure of an MCG cell switch triggered by a cell switch command received from a network.

[0426] In step S1205, the UE may perform a first cell selection based on detecting the failure.

[0427] In step S1207, based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, the UE may perform a cell switch execution to the candidate cell.

[0428] In step S1209, the UE may remove the one or more candidate configurations for conditional mobility based on performing the cell switch execution.

[0429] According to various embodiments, the UE may remove the one or more candidate configurations for cell switch based on performing the cell switch execution.

[0430] According to various embodiments, the UE may detect a failure of the cell switch execution. The UE may perform a second cell selection based on detecting the failure of the cell switch execution. The UE may transmit an RRC re-establishment request message to a cell selected by the second cell selection, based on the cell selected by the second cell selection being a candidate cell related to the one or more candidate configurations for conditional mobility that had been removed before.

[0431] Hereinafter, detailed implementations regarding handling of candidate configurations for CHO when performing LTM-based recovery are described.

[0432] According to implementations of the present disclosure, UE may be configured with conditional reconfiguration for CHO or CPAC, and the UE may also be configured with LTM configuration with LTM candidates. If the UE performs LTM-based (failure) recovery by executing LTM to the selected cell during the failure recovery / RRC re-establishment procedure, the UE may discard / remove the stored conditional reconfiguration / candidate configurations for CHO. UE may discard / remove the stored candidate configuration(s) for LTM when performing LTM-based recovery. As a result of the discarding / removal, if the LTM-based recovery fails (i.e., LTM execution to the selected cell during the recovery procedure is not successful), UE does not re-attempt another failure recovery based on CHO / CPAC-based recovery or based on LTM-based recovery, but performs legacy connection re-establishment procedure by initiating a cell selection procedure and by transmittingRRCReestablishmentRequestmessage to the selected cell.

[0433] For example, the UE may perform the following actions as specified in table 5 below:

[0434] 5.3.5.3 Reception of anRRCReconfigurationby the UEThe UE shall perform the following actions upon reception of theRRCReconfiguration,upon execution of the conditional reconfiguration (CHO, CPA or CPC), or upon execution of an LTM cell switch:1>　 if theRRCReconfigurationis applied due to a conditional reconfiguration execution upon cell selection performed while timer T311 was running, as defined in 5.3.7.3; or1> if theRRCReconfigurationis applied due to a LTM cell switch execution upon cell selection performed while timer T311 was running, as defined in 5.3.7.3:2>　 remove all the entries within the MCG and the SCGVarConditionalReconfig(i.e., remove all the MCG / SCG candidate configurations for conditional mobility), if any;[...]

[0435] FIG. 13 shows an example of a method for notifying a candidate configuration that is applied for LTM / cell switch according to an embodiment of the present disclosure.Referring to FIG. 13, in step S1301, the UE may receive an LTM configuration (e.g.,LTM-Config) comprising one or more candidate cell configurations for LTM cell switch (e.g., one or moreLTM-Candidates).

[0436] The candidate cell configuration may comprise:

[0437] - a part that the UE applies directly at the time of LTM execution; and / or

[0438] - another part that the UE selectively applies based on the indications included in the LTM cell switch command upon LTM execution.

[0439] One or more candidate serving cells can be configured. Candidate serving cells may belong to the same CU (i.e., intra-CU LTM), or different CUs (i.e., inter-CU LTM).

[0440] Two or more candidate cell configurates can be provided for a specific cell by the RRC reconfiguration message for at least one of reconfiguration, LTM preparation, conditional reconfiguration and / or reconfiguration with synchronization (i.e., synchronous reconfiguration).

[0441] A candidate cell configuration may comprise at least one of:

[0442] - configurations for a special cell (SpCell), servingCellConfigCommon,servingCellConfig,reconfigurationWithSync, and / or RLF relevant configuration;

[0443] - configuations for SCells,servingCellConfigCommon,servingCellConfig,smtc, and / or DRX configuration;

[0444] - MAC / RLC related configurations; or

[0445] - Set of BWP configurations: for each BWP configuration, a flag may be included to indicate whether the UE firstly applies upon LTM execution or not. Sets of configurations for a physical channel (e.g., set of PUCCH configurations, set of PUSCH configurations, set of PDCCH configurations, set of PDSCH configurations and / or set of PRACH configurations) can be included in each BWP configuration. For each physical channel configuration in a set, a flag may be included to indicate whether the UE firstly applies upon LTM execution or not.

[0446] In step S1303, the UE may receive a conditional reconfiguration (e.g.,ConditionalReconfiguration) comprising one or more candidate cell configurations for CHO (e.g., one or morecondReconfigToAddMods).

[0447] The conditional reconfiguration (or, CHO configuration) comprises at least one of a list ofRRCReconfigurationmessages of candidate cells (e.g., a list of configurations of candidate cells for conditional mobility), associated execution conditions, or required conditional measurements. A candidate cell configuration for CHO may comprise at least one of a configuration of the related target cell (e.g.,RRCReconfigurationmessage), the associated execution condition(s) for the target cell, or required conditional measurements related to the target cell.

[0448] One or more serving cells can be configured for CHO. Candidate serving cells may belong to different CUs or the same CU.

[0449] CHO can be configured for LTM candidate cells. That is, both CHO and LTM can be configured for one or more candidate cells.

[0450] Although step S1301 is illustrated as being performed before step S1303 in FIG. 13, step S1303 may be performed before step S1301, or steps S1301 and S1303 may be performed simultaneously. For example, the UE may receive an RRC reconfiguration message that includes both the LTM configuration in step S1301 and the conditional reconfiguration in step S1303.

[0451] In step S1305, the UE may detect a failure condition (e.g., radio link failure, handover failure, and / or reconfiguration failure).

[0452] In step S1307, the UE may initiate RRC re-establishment procedure and then perform a cell selection procedure.

[0453] For example, the selected cell may be either CHO candidate cell or LTM candidate cell.

[0454] For example, the selected cell may be both CHO and LTM candidate cell.

[0455] For example, the selected cell may be neither CHO candidate cell nor LTM candidate cell.

[0456] In step S1309, the UE may perform an LTM-based recovery when the selected cell is an LTM candidate cell.

[0457] The LTM-based recovery may comprise:

[0458] - LTM execution to the selected cell (i.e., the LTM candidate cell);

[0459] - removal of the stored conditional configuration (including all or at least one of the stored candidate configurations for conditional mobility (e.g.,condReconfigToAddMods)) for MCG;

[0460] - removal of the stored conditional configuration (including all or at least one of the stored candidate configurations for conditional mobility (e.g.,condReconfigToAddMods)) for SCG;

[0461] - removal of the stored LTM configuration (including all or at least one of the stored candidate configurations for LTM (e.g.,LTM-Candidates)) for MCG; and / or

[0462] - removal of the stored LTM configuration (including all or at least one of the stored candidate configurations for LTM (e.g.,LTM-Candidates)) for SCG.

[0463] In step S1311, upon detecting a failure of the LTM-based recovery, the UE may initiate the RRC re-establishment procedure and then perform a cell selection procedure.

[0464] In step S1313, the UE may transmit anRRCReestablishmentRequestmessage to the selected cell.

[0465] Furthermore, the method in perspective of the UE described in the present disclosure (e.g., in FIG. 11) may be performed by the first wireless device 100 shown in FIG. 2 and / or the UE 100 shown in FIG. 3.

[0466] More specifically, the UE comprises at least one transceiver, at least processor, and at least one computer memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations.

[0467] The operations comprise: receiving one or more candidate configurations for conditional mobility and one or more candidate configurations for cell switch, wherein each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch is related to a corresponding candidate cell; detecting a failure; performing a first cell selection based on detecting the failure; based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, performing a cell switch execution to the candidate cell; and removing the one or more candidate configurations for conditional mobility based on performing the cell switch execution.

[0468] Furthermore, the method in perspective of the UE described in the present disclosure (e.g., in FIG. 11) may be performed by a software code 105 stored in the memory 104 included in the first wireless device 100 shown in FIG. 2.

[0469] More specifically, at least one computer readable medium (CRM) stores instructions that, based on being executed by at least one processor, perform operations comprising: receiving one or more candidate configurations for conditional mobility and one or more candidate configurations for cell switch, wherein each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch is related to a corresponding candidate cell; detecting a failure; performing a first cell selection based on detecting the failure; based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, performing a cell switch execution to the candidate cell; and removing the one or more candidate configurations for conditional mobility based on performing the cell switch execution.

[0470] Furthermore, the method in perspective of the UE described in the present disclosure (e.g., in FIG. 11) may be performed by control of the processor 102 included in the first wireless device 100 shown in FIG. 2 and / or by control of the processor 102 included in the UE 100 shown in FIG. 3.

[0471] More specifically, an apparatus configured to / adapted to operate in a wireless communication system (e.g., communication device / UE) comprises at least processor, and at least one computer memory operably connectable to the at least one processor. The at least one processor is configured to / adapted to perform operations comprising: receiving one or more candidate configurations for conditional mobility and one or more candidate configurations for cell switch, wherein each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch is related to a corresponding candidate cell; detecting a failure; performing a first cell selection based on detecting the failure; based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, performing a cell switch execution to the candidate cell; and removing the one or more candidate configurations for conditional mobility based on performing the cell switch execution.

[0472] Furthermore, the method in perspective of a network node described in the present disclosure (e.g., in FIG. 12) may be performed by the second wireless device 200 shown in FIG. 2. The network node may be related to a serving cell.

[0473] More specifically, the network node comprises at least one transceiver, at least processor, and at least one computer memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations.

[0474] The operations comprise: transmitting, to a user equipment (UE), more candidate configurations for conditional mobility and one or more candidate configurations for cell switch, wherein each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch is related to a corresponding candidate cell, and wherein the UE is configured to perform operations comprising: detecting a failure; performing a first cell selection based on detecting the failure; based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, performing a cell switch execution to the candidate cell; and removing the one or more candidate configurations for conditional mobility based on performing the cell switch execution.

[0475] The present disclosure may have various advantageous effects.

[0476] For example, UE discards / removes the stored conditional reconfigurations (i.e., stored candidate configurations for conditional mobility) when performing LTM-based recovery. To this end, the data interruption can be reduced by preventing repeated fast recovery based on the stored conditional reconfigurations.

[0477] Advantageous effects which can be obtained through specific embodiments of the present disclosure are not limited to the advantageous effects listed above. For example, there may be a variety of technical effects that a person having ordinary skill in the related art can understand and / or derive from the present disclosure. Accordingly, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that may be understood or derived from the technical features of the present disclosure.

[0478] Claims in the present disclosure can be combined in a various way. For instance, technical features in method claims of the present disclosure can be combined to be implemented or performed in an apparatus, and technical features in apparatus claims can be combined to be implemented or performed in a method. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in an apparatus. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in a method. Other implementations are within the scope of the following claims.

Claims

1.A method comprising:receiving one or more candidate configurations for conditional mobility and one or more candidate configurations for cell switch,wherein each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch is related to a corresponding candidate cell;detecting a failure;performing a first cell selection based on detecting the failure;based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, performing a cell switch execution to the candidate cell; andremoving the one or more candidate configurations for conditional mobility based on performing the cell switch execution.2.The method of claim 1, further comprising after receiving the one or more candidate configurations for conditional mobility, storing the received one or more candidate configurations for conditional mobility in a list of candidate configurations for conditional mobility,wherein the removing of the one or more candidate configurations for conditional mobility comprises removing all candidate configurations for conditional mobility in the list of candidate configurations for conditional mobility.3.The method of claim 1, further comprising removing the one or more candidate configurations for cell switch based on performing the cell switch execution.4.The method of claim 3, further comprising after receiving the one or more candidate configurations for cell switch, storing the received one or more candidate configurations for cell switch in a list of candidate configurations for cell switch,wherein the removing of the one or more candidate configurations for cell switch comprises removing all candidate configurations for cell switch in the list of candidate configurations for cell switch.5.The method of claim 1, wherein the performing of the cell switch execution to the candidate cell comprises applying a radio resource control (RRC) reconfiguration in the candidate configuration for cell switch related to the candidate cell, andwherein the removing of the one or more candidate configurations for conditional mobility comprises removing the one or more candidate configurations for conditional mobility based on applying the candidate configuration for cell switch.6.The method of claim 1, wherein the candidate cell selected by the first cell selection is related to both of the candidate configuration for cell switch and a candidate configuration for conditional mobility, andwherein the removing of the one or more candidate configurations for conditional mobility comprises removing the candidate configuration for conditional mobility related to the candidate cell based on performing the cell switch execution to the candidate cell.7.The method of claim 1, wherein the failure comprises at least one of a radio link failure of a master cell group (MCG), or a failure of an MCG cell switch triggered by a cell switch command received from a network.8.The method of claim 1, wherein the cell switch execution is performed based on a cell switch attempt configuration being configured.9.The method of claim 1, further comprising:detecting a failure of the cell switch execution;performing a second cell selection based on detecting the failure of the cell switch execution; andtransmitting a radio resource control (RRC) re-establishment request message to a cell selected by the second cell selection.10.The method of claim 9, wherein the RRC re-establishment request message is transmitted to the cell selected by the second cell selection, based on the cell selected by the second cell selection being a candidate cell related to the one or more candidate configurations for conditional mobility that had been removed before.11.The method of claim 9, wherein the RRC re-establishment request message is transmitted to the cell selected by the second cell selection, based on a conditional mobility attempt configuration being configured.12.The method of claim 1, wherein the cell switch execution comprises a layer 1 / layer 2 (L1 / L2) triggered mobility (LTM) execution.13.The method of claims 1, wherein the method is performed by a user equipment (UE) in communication with at least one of a mobile device, a network, or autonomous vehicles.14.A user equipment (UE) comprising:at least one transceiver;at least one processor; andat least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:receiving one or more candidate configurations for conditional mobility and one or more candidate configurations for cell switch,wherein each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch is related to a corresponding candidate cell;detecting a failure;performing a first cell selection based on detecting the failure;based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, performing a cell switch execution to the candidate cell; andremoving the one or more candidate configurations for conditional mobility based on performing the cell switch execution.15.An apparatus comprising:at least processor; andat least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:receiving one or more candidate configurations for conditional mobility and one or more candidate configurations for cell switch,wherein each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch is related to a corresponding candidate cell;detecting a failure;performing a first cell selection based on detecting the failure;based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, performing a cell switch execution to the candidate cell; andremoving the one or more candidate configurations for conditional mobility based on performing the cell switch execution.16.A non-transitory computer readable medium (CRM) having stored thereon a program code implementing instructions that, based on being executed by at least one processor, perform operations comprising:receiving one or more candidate configurations for conditional mobility and one or more candidate configurations for cell switch,wherein each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch is related to a corresponding candidate cell;detecting a failure;performing a first cell selection based on detecting the failure;based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, performing a cell switch execution to the candidate cell; andremoving the one or more candidate configurations for conditional mobility based on performing the cell switch execution.17.A method comprising:transmitting, to a user equipment (UE), more candidate configurations for conditional mobility and one or more candidate configurations for cell switch,wherein each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch is related to a corresponding candidate cell, andwherein the UE is configured to perform operations comprising:detecting a failure;performing a first cell selection based on detecting the failure;based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, performing a cell switch execution to the candidate cell; andremoving the one or more candidate configurations for conditional mobility based on performing the cell switch execution.18.A network node comprising:at least one transceiver;at least one processor; andat least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:transmitting, to a user equipment (UE), more candidate configurations for conditional mobility and one or more candidate configurations for cell switch,wherein each of the one or more candidate configurations for conditional mobility and the one or more candidate configurations for cell switch is related to a corresponding candidate cell, andwherein the UE is configured to:detect a failure;perform a first cell selection based on detecting the failure;based on a cell selected by the first cell selection being a candidate cell related to a candidate configuration for cell switch, perform a cell switch execution to the candidate cell; andremove the one or more candidate configurations for conditional mobility based on performing the cell switch execution.19.The network node of claim 18, the UE being further configured to remove the one or more candidate configurations for cell switch based on performing the cell switch execution.20.The method of claim 18, the UE being further configured to:detect a failure of the cell switch execution;perform a second cell selection based on detecting the failure of the cell switch execution; andtransmit a radio resource control (RRC) re-establishment request message to a cell selected by the second cell selection, based on the cell selected by the second cell selection being a candidate cell related to the one or more candidate configurations for conditional mobility that had been removed before.

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