Prevention of invalid cell switch

Abstract

The present disclosure is related to preventing invalid cell switch in wireless communications. According to an embodiment of the present disclosure, a method performed by a user equipment (UE) comprises: receiving a candidate configuration for cell switch related to a first candidate cell, wherein the candidate configuration comprises: a configuration of the first candidate cell; one or more execution conditions for cell switch to the first candidate cell; and an identifier (ID) related to the first candidate cell; evaluating the one or more execution conditions for cell switch to the first candidate cell; and applying the configuration of the first candidate cell based on: i) at least one of the one or more execution conditions being fulfilled; and ii) the ID related to the first candidate cell being equal to an ID related to a serving cell.

Description

PREVENTION OF INVALID CELL SWITCH

[0001] The present disclosure is related to preventing invalid cell switch 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 a wireless communication system, L1 / L2 Triggered Mobility (LTM)　has been introduced to minimize interruption time during cell mobilities. Unlike conventional Layer 3 (L3) mobilities, which rely on RRC (Radio Resource Control) signaling, LTM enables faster cell switching by utilizing lower-layer signaling (Layer 1 or Layer 2) based on pre-configured candidate cells.

[0006] However, in certain cases, an LTM cell switch may be　invalid. For instance, if a　conditional LTM (CLTM)　is performed toward an　inter-CU candidate cell, such an LTM cell switch may be rendered invalid.

[0007] An aspect of the present disclosure is to provide method and apparatus for preventing invalid cell switch in a wireless communication system.

[0008] According to an embodiment of the present disclosure, a method performed by a user equipment (UE) comprises: receiving a candidate configuration for cell switch related to a first candidate cell, wherein the candidate configuration comprises: a configuration of the first candidate cell; one or more execution conditions for cell switch to the first candidate cell; and an identifier (ID) related to the first candidate cell; evaluating the one or more execution conditions for cell switch to the first candidate cell; and applying the configuration of the first candidate cell based on: i) at least one of the one or more execution conditions being fulfilled; and ii) the ID related to the first candidate cell being equal to an ID related to a serving cell.

[0009] According to an embodiment of the present disclosure, a method performed by a network node comprises: transmitting, to a user equipment (UE), a candidate configuration for cell switch related to a first candidate cell, wherein the candidate configuration comprises: a configuration of the first candidate cell; one or more execution conditions for cell switch to the first candidate cell; and an identifier (ID) related to the first candidate cell, wherein the configuration of the first candidate cell is applied based on: i) at least one of the one or more execution conditions being fulfilled; and ii) the ID related to the first candidate cell being equal to an ID related to a serving cell.

[0010] According to various embodiments, apparatuses to implement the above methods are provided.

[0011] The present disclosure may have various advantageous effects.

[0012] For example, the network signalling overhead due to reconfiguration of LTM configuration for every inter-CU LTM cell switch execution can be prevented. Further, the UE interruption due to mobility failure incurred by invalid CLTM cell switch execution can be prevented.

[0013] 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.

[0014] FIG. 1 shows an example of a communication system to which implementations of the present disclosure is applied.

[0015] FIG. 2 shows an example of wireless devices to which implementations of the present disclosure is applied.

[0016] FIG. 3 shows an example of UE to which implementations of the present disclosure is applied.

[0017] 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.

[0018] FIG. 6 shows a frame structure in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

[0019] FIG. 7 shows a data flow example in the 3GPP NR system to which implementations of the present disclosure is applied.

[0020] FIG. 8 shows an example of overall architecture of RAN.

[0021] FIG. 9 shows an example of a signalling procedure for LTM.

[0022] FIG. 10 shows an example of a signalling procedure for CLTM.

[0023] FIG. 11 shows an example of a method performed by a UE for preventing invalid cell switch according to various embodiments of the present disclosure.

[0024] FIG. 12 shows an example of a signal flow between UE and network node for preventing invalid cell switch according to various embodiments 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 RAN; establishment, maintenance and release of an RRC connection between the UE and RAN; security functions including key management; establishment, configuration, maintenance and release of signalling 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 f = 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 f = 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 f = 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 signalling (e.g., RRC signalling), 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] FIG. 8 shows an example of overall architecture of RAN.

[0105] Referring to FIG. 8, the radio access network (RAN) consists of a set of gNBs connected to the 5GC through the NG interface.

[0106] A gNB can support FDD mode, TDD mode or dual mode operation.

[0107] gNBs can be interconnected through the Xn interface.

[0108] A gNB may consist of a gNB-CU and one or more gNB-DU(s). A gNB-CU and a gNB-DU is connected via F1 interface.

[0109] One gNB-DU is connected to only one gNB-CU.

[0110] In case of network sharing with multiple cell ID broadcast, each Cell Identity associated with a subset of PLMNs corresponds to a gNB-DU and the gNB-CU it is connected to, i.e. the corresponding gNB-DUs share the same physical layer cell resources.

[0111] For resiliency, a gNB-DU may be connected to multiple gNB-CUs by appropriate implementation.

[0112] NG, Xn and F1 are logical interfaces.

[0113] For RAN, the NG and Xn-C interfaces for a gNB consisting of a gNB-CU and gNB-DUs, terminate in the gNB-CU. For EN-DC, the S1-U and X2-C interfaces for a gNB consisting of a gNB-CU and gNB-DUs, terminate in the gNB-CU. The gNB-CU and connected gNB-DUs are only visible to other gNBs and the 5GC as a gNB.

[0114] The node hosting user plane part of NR PDCP (e.g. gNB-CU, gNB-CU-UP, and for EN-DC, MeNB or SgNB depending on the bearer split) shall perform user inactivity monitoring and further informs its inactivity or (re)activation to the node having C-plane connection towards the core network (e.g. over E1, X2). The node hosting NR RLC (e.g., gNB-DU) may perform user inactivity monitoring and further inform its inactivity or (re)activation to the node hosting control plane, e.g., gNB-CU or gNB-CU-CP.

[0115] UL PDCP configuration (i.e., how the UE uses the UL at the assisting node) is indicated via X2-C (for EN-DC), Xn-C (for RAN) and F1-C. Radio Link Outage / Resume for DL and / or UL is indicated via X2-U (for EN-DC), Xn-U (for RAN) and F1-U.

[0116] The RAN is layered into a Radio Network Layer (RNL) and a Transport Network Layer (TNL).

[0117] The RAN architecture, i.e., the RAN logical nodes and interfaces between them, is defined as part of the RNL.

[0118] For each RAN interface (NG, Xn, F1) the related TNL protocol and the functionality are specified. The TNL provides services for user plane transport, signalling transport.

[0119] In NG-Flex configuration, each RAN node is connected to all AMFs of AMF Sets within an AMF Region supporting at least one slice also supported by the RAN node.

[0120] The RAN supports Multi-Radio Dual Connectivity (MR-DC) operation. In MR-DC, a multiple Rx / Tx capable UE may be configured to utilize resources provided by two different nodes connected via non-ideal backhaul, one providing NR access and the other one providing either E-UTRA or NR access. One node acts as the MN and the other as the SN. The MN and SN are connected via a network interface and at least the MN is connected to the core network.

[0121] The MN and / or the SN can be operated with shared spectrum channel access.

[0122] The MN may be associated with a master cell group (MCG) which is a group of serving cells comprising of the SpCell (PCell) and optionally one or more SCells.

[0123] The SN may be associated with a secondary cell group (SCG) which is a group of serving cells comprising of the SpCell (PSCell) and optionally one or more SCells.

[0124] In MR-DC, UE may be configured with MCG and SCG.

[0125] MR-DC is designed based on the assumption of non-ideal backhaul between the different nodes but can also be used in case of ideal backhaul.

[0126] All MR-DC normative text and procedures in this version of the specification show the aggregated node case.

[0127] Hereinafter, a description will be given of mobility.

[0128] The mobility may comprise PCell change, PSCell change (or, secondary node (SN) change), and / or PSCell addition (or, SN addition).

[0129] 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.

[0130] In the present disclosure, the terms "handover" and "mobility" can be used interchangeably.

[0131] In the present disclosure, the description regarding handover can also be applied to other mobility procedures (e.g., PSCell change / addition).

[0132] For example, there may be a mobility called L1 / L2-triggered mobility (LTM)(or, cell switch).

[0133] LTM is a procedure in which a gNB receives L1 or L3 measurement report(s) from a UE, and on their basis the gNB may change UE serving cell by a cell switch command signalled via a MAC CE. The cell switch command indicates an LTM candidate configuration that the gNB previously prepared and provided to the UE through RRC signalling. Then the UE switches to the target configuration according to the cell switch command. The LTM procedure can be used to reduce the mobility latency.

[0134] 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. All the activated TCI states except those received in the cell switch command are deactivated upon LTM cell switch execution.

[0135] When configured by the network, it is possible to initiate UL TA acquisition (called early TA) procedure of one or multiple cells that are different from the current serving cells. If the cell has the same NTA as the current serving cells or NTA=0, early TA acquisition procedure is not required. The network may request the UE to perform early TA acquisition of a candidate cell before a cell switch. The early TA acquisition procedure is triggered by PDCCH order or realized through UE-based TA measurement as configured by RRC. In the former case, the gNB / gNB-DU to which the candidate cell belongs calculates the TA value and sends it to the gNB / gNB-DU to which the serving cell belongs via gNB-CU. 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 performs TA measurement for the candidate cells after being configured by RRC but the exact time the UE performs TA measurement is up to UE implementation. The UE applies the TA value measured by itself and performs RACH-less LTM upon receiving the cell switch command, if it does not include any valid TA value. The network may also send a TA value in the LTM cell switch command MAC CE without early TA acquisition.

[0136] When two TAG IDs are configured for an LTM candidate cell, the gNB-DU to which the LTM candidate cell belongs assigns the same TAG ID pointer value for each TRP to be used by the UEs.

[0137] Depending on the availability of a valid TA value, the UE performs either a RACH-less LTM or RACH-based LTM cell switch. If the valid TA value is provided in the cell switch command, the UE applies the TA value as instructed by the network. In the case where UE-based TA measurement is configured, but no valid TA value is provided in the cell switch command, the UE applies the valid TA value by itself if available. The UE performs RACH-less LTM cell switch upon receiving the cell switch command whenever a valid TA value is available. If no valid TA value is available, the UE performs RACH-based LTM cell switch.

[0138] Regardless of whether the UE is configured for UE-based TA measurement for a certain candidate cell, it will still follow the PDCCH order, which includes performing a random access procedure towards one or more candidate cells.

[0139] This also applies to the candidate cells for which the UE is capable of deriving TA values by itself. Additionally, regardless of whether the UE has already performed a random access procedure towards the candidate cells, it will still follow the UE-based measurement configuration if configured by the network.

[0140] For RACH-less LTM, the UE accesses the target cell using either a configured grant or a dynamic grant. The configured grant is provided in the LTM candidate configuration, and the UE selects the configured grant occasion associated with the beam indicated in the cell switch command. Upon initiation of LTM cell switch to the target cell, the UE starts to monitor PDCCH on the target cell for dynamic scheduling. 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.

[0141] The following principles apply to LTM:

[0142] - Security keys are maintained upon an LTM cell switch;

[0143] - Subsequent LTM is supported.

[0144] LTM supports both intra-gNB-DU and inter-gNB-DU mobility within the same gNB-CU. LTM supports both intra-frequency and inter-frequency mobility, including mobility to inter-frequency cell that is not a current serving cell.

[0145] LTM is supported only for licensed spectrum. The following scenarios are supported:

[0146] - PCell change in non-CA scenario and non-DC scenario;

[0147] - PCell and SCell(s) change in CA scenario;

[0148] - Dual connectivity scenario: including PCell and MCG SCell(s) change and intra-SN PSCell and SCG SCell(s) change without MN involvement. LTM for simultaneous PCell and PSCell change is not supported.

[0149] While the UE has stored LTM candidate configurations the UE can also execute any L3 handover except for DAPS handover. In the RRC message which the UE applies for any L3 handover (except DAPS), LTM candidate configurations can be added / modified / released by the target cell.

[0150] Cell switch command is conveyed in a MAC CE, which contains the necessary information to perform the LTM cell switch.

[0151] 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 the need to release, reconfigure or add other LTM candidate configurations after each LTM cell switch completion.　The general procedure over the air interface may also be applicable to SCG LTM.

[0152] FIG. 9 shows an example of a signalling procedure for LTM.

[0153] Referring to FIG. 9, in step S901, the UE may send aMeasurementReportmessage to the gNB. The gNB decides to configure LTM and initiates LTM preparation.

[0154] In step S903, the gNB may transmit 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 (e.g.,ltm-CandidateToAddModList) comprising one or more LTM candidate configurations (e.g.,ltm-Candidate). Each LTM candidate configuration may comprise a configuration of a corresponding candidate cell (e.g.,ltm-CandidateConfigcontainingRRCReconfiguration). That is, the network may configure the UE with one or more LTM candidate configurations within theLTM-ConfigIE.

[0155] In step S905, the UE may store the LTM configuration / cell switch configuration comprising the list of LTM candidate configurations, and transmit anRRCReconfigurationCompletemessage to the gNB.

[0156] In step S907, the UE may perform DL / UL synchronization with the LTM candidate cell(s) before receiving the cell switch command.

[0157] In some implementations, the UE may perform DL synchronization with the LTM candidate cell(s) before receiving the cell switch command. The UE may activate and deactivate TCI states of LTM candidate cell(s), as triggered by the gNB.

[0158] In some implementations, the UE may perform UL synchronization with LTM candidate cell(s) before receiving the cell switch command, by using UE-based timing advance (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. 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 does not 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 does not maintain the TA timer for the candidate cell and relies on network implementation to guarantee the TA validity.

[0159] In step S9010, the UE may perform L1 measurements on the configured LTM candidate cell(s) and transmit L1 measurement reports to the gNB. L1 measurement should be performed as long as RRC reconfiguration (step S903) is applicable. The UE can also perform L3 measurement reporting to the gNB, including beam level measurement results on cell(s) which are configured as LTM candidate cell(s) according to the received network configuration.

[0160] In step S911, the gNB may decide to execute cell switch to a target cell and transmit 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 (e.g.,ltm-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 the candidate configuration (e.g.,ltm-CandidateConfig) indicated by the target configuration ID.

[0161] In step S913, the UE may perform the random access procedure towards the target cell, if UE does not have valid TA of the target cell. 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).

[0162] When performing the random access procedure / RACH procedure: i) the UE may perform a contention-free random access (CFRA) if CFRA resources / dedicated RACH configuration is available to the UE; and ii) the UE may perform a contention-based random access (CBRA) if CFRA resources / dedicated RACH configuration is not available to the UE.

[0163] For the CBRA, the UE may transmit a random access preamble in uplink, to a RAN node. The UE may transmit a message 1 (MSG1) comprising the random access preamble to the RAN node. The random access preamble may be associated with a random access - radio resource temporary identifier (RA-RNTI). The random access preamble may be selected based on the selected RACH resources, and transmitted through a time / frequency resources identified by the selected RACH resources.

[0164] For the CFRA, the UE may transmit a dedicated random access preamble in uplink, to a RAN node. The UE may transmit an MSG1 comprising the dedicated random access preamble to the RAN node. The dedicated random access preamble may be associated with a RA-RNTI. The dedicated random access preamble may be selected based on the CFRA resources / dedicated RACH configuration, and transmitted through a time / frequency resources identified by the CFRA resources / dedicated RACH configuration.

[0165] In step S915, the UE may complete the LTM cell switch procedure by sendingRRCReconfigurationCompletemessage to target cell. If the UE has performed a RA procedure in step S913, 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.

[0166] The steps S907 to S915 can be performed multiple times for subsequent LTM cell switch executions using the LTM candidate configuration(s) provided in step S903.

[0167] The procedure over the air interface described in FIG. 9 is applicable to both intra-gNB-CU / DU LTM and inter-gNB-CU / DU LTM.

[0168] Further, LTM may be executed conditionally, which may be referred to as　conditional LTM (CLTM). In CLTM, the UE may execute LTM without reception of an execution command (e.g., LTM cell switch command) from the network. Thus, for the execution of CLTM, when one or more L1 measurement event conditions (or, one or more L1 conditions) are configured, the UE may perform CLTM to a candidate cell based on at least one beam from a beam set configured for the candidate cell satisfying at least one of the one or more L1 measurement event conditions. For example, the L1 condition may comprise at least one of event LTM2, event LTM3, event LTM4, or event LTM5.

[0169] The overall procedure for CLTM is as shown in FIG. 10.

[0170] FIG. 10 shows an example of a signalling procedure for CLTM.

[0171] Referring to FIG. 10, in step S1001, the UE sends aMeasurementReportmessage to the gNB. The gNB decides to configure CLTM and initiates CLTM preparation.

[0172] In step S1003, the source gNB can request the candidate cells to provide conditional execution configurations and the candidate cells provide the conditional configuration including their own execution conditions, to be used in subsequent CLTM.

[0173] In step S1005, the source gNB sends anRRCReconfigurationmessage to the UE and this includes the CLTM configurations of candidate cells as well as the execution condition for the CLTM. TheRRCReconfigurationmessage may comprise an LTM configuration / cell switch configuration (e.g.,LTM-Config) comprising a list of LTM candidate configurations (e.g.,ltm-CandidateToAddModList) comprising one or more LTM candidate configurations (e.g.,ltm-Candidate). Each LTM candidate configuration may comprise a configuration of a corresponding candidate cell (e.g.,ltm-CandidateConfigcontainingRRCReconfiguration). That is, the network may configure the UE with one or more CLTM candidate configurations within theLTM-Config.

[0174] Each LTM candidate configuration may comprise a list of execution conditions for CLTM (e.g.,LTM-ExecutionConditionList) comprising one or more execution conditions for CLTM (e.g.,LTM-ExecutionCondition). Alternatively, each LTM candidate configuration may be included in the LTM configuration / cell switch configuration comprising the list of execution conditions for CLTM (e.g.,LTM-ExecutionConditionList, which is also referred to asltm-ServingCellExecutionConditionin this case). These LTM candidate configuration may be referred to as CLTM (candidate) configuration.

[0175] In step S1007, the UE stores the CLTM candidate configurations and transmits anRRCReconfigurationCompletemessage to the gNB. The UE starts evaluating the execution conditions based on the provided configuration.

[0176] In step S1009, the source gNB can trigger early synchronization (for example, based on the L1 or L3 measurement reports from the UE, if configured) to the UE and step S907 in FIG. 9 is applicable here as well. In addition, the source gNB can provide the TA value for each of the candidate cells the UE has performed UL synchronization with.

[0177] In step S1011, the CLTM execution condition (e.g.,ltm-ExecutionCondition) is satisfied at the UE and on the satisfied candidate LTM cell, the UE performs the CLTM switch by applying the configuration (e.g.,ltm-CandidateConfig / RRCReconfiguration) of the satisfied LTM candidate cell. If the UE has valid TA as part of the UL early synchronization from step S1009, the UE skips RACH. Otherwise, RACH is performed as part of the CLTM switch.

[0178] In step S1013, the UE completes the CLTM cell switch procedure by sendingRRCReconfigurationCompletemessage to the switched LTM cell as in step S915 from FIG. 9. The UE does not release any valid TA value(s) of LTM candidate cells with CLTM configuration.

[0179] The steps S1009 to S1013 can be performed multiple times for subsequent CLTM cell switch executions using the CLTM candidate configuration(s) provided in step S1005.

[0180] The following principles apply to CLTM:

[0181] - CLTM is supported for intra-gNB LTM and / or inter-gNB LTM;

[0182] - CLTM can be RACH-based or RACH-less. RACH-based CLTM includes CFRA and CBRA, and only CG based RACH-less CLTM is supported;

[0183] - Since there is no LTM cell switch command MAC CE reception for CLTM, the UE performs MAC reset as part of the CLTM execution.

[0184] Further, LTM may be executed subsequently, which may be referred to as subsequent LTM. The subsequent LTM may comprise repeating LTM execution / completion after each LTM execution / completion based on a corresponding candidate configuration without releasing the candidate configuration and / or other candidate configurations. That is, the subsequent LTM may refer to LTM that is performed without reconfiguration and / or re-initialization of the LTM preparation from a network after a previous LTM. For example, when a UE has received a plurality of candidate configurations, after the UE performs LTM based on a corresponding candidate configuration, the UE does not release the candidate configuration and / or other candidate configurations, and may perform a subsequent LTM based on a corresponding candidate configuration among the already received / configured candidate configurations without reconfiguration and / or re-initialization of the LTM preparation from the network (or, without receiving new candidate configurations from the network). This results in a reduction of the signalling overhead and / or interrupting time for LTM. The subsequent　LTM　can also be applied to　CLTM, which may be referred to as　subsequent CLTM.

[0185] The IEs in the LTM configuration / cell switch configuration (e.g.,LTM-Config) are shown in table 5:

[0186] LTM-Config-r18 ::= SEQUENCE {ltm-ReferenceConfiguration-r18 SetupRelease {ReferenceConfiguration-r18} OPTIONAL, -- Cond NR-DCltm-CandidateToReleaseList-r18 SEQUENCE (SIZE (1..maxNrofLTM-Configs-r18)) OF LTM-CandidateId-r18 OPTIONAL, -- Need Nltm-CandidateToAddModList-r18 SEQUENCE (SIZE (1..maxNrofLTM-Configs-r18)) OF LTM-Candidate-r18 OPTIONAL, -- Need Nltm-ServingCellNoResetID-r18 INTEGER (1..maxNrofLTM-Configs-plus1-r18) OPTIONAL, -- Need Nltm-CSI-ResourceConfigToAddModList-r18 SEQUENCE (SIZE (1..maxNrofLTM-CSI-ResourceConfigurations-r18)) OF LTM-CSI-ResourceConfig-r18OPTIONAL, -- Need Nltm-CSI-ResourceConfigToReleaseList-r18 SEQUENCE (SIZE (1..maxNrofLTM-CSI-ResourceConfigurations-r18)) OF LTM-CSI-ResourceConfigId-r18OPTIONAL, -- Need NattemptLTM-Switch-r18 ENUMERATED {true} OPTIONAL, -- Cond LTM-MCGltm-ServingCellUE-MeasuredTA-ID-r18 INTEGER (1..maxNrofLTM-Configs-plus1-r18) OPTIONAL, -- Need N...,[[ltm-ServingCellNoSecurityChangeID-r19 LTM-NoSecurityChangeId-r19 OPTIONAL, -- Need Nltm-ServingCellExecutionCondition-r19 SetupRelease {LTM-ExecutionConditionList-r19} OPTIONAL -- Need M]]}

[0187] In table 5:

[0188] -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;

[0189] -ltm-CandidateToAddModList: a list of LTM candidate configurations (e.g.,LTM-Candidate(s)) related to candidate SpCells to be added or modified for LTM;

[0190] -ltm-CandidateToReleaseList: a list of LTM candidate configuration IDs (e.g.,LTM-CandidateId(s)) related to candidate SpCells to be removed;

[0191] -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;

[0192] -ltm-ServingCellUE-MeasuredTA-ID: serving cell ID based on which the UE determines whether UE-based TA measurements are needed or not;

[0193] -ltm-ServingCellNoSecurityChangeID: ID associated with the serving cell based on which the UE determines whether a security change is needed or not upon an LTM cell switch procedure.

[0194] -ltm-ServingCellExecutionCondition: This field can only be included within anltm-Configassociated with the MCG.

[0195] The IEs in the LTM configuration / cell switch configuration for NR-DC (e.g.,LTM-ConfigNRDC) are shown in table 6:

[0196] LTM-ConfigNRDC-r19 ::= SEQUENCE {ltm-ConfigurationSCG-r19 SetupRelease {LTM-Config-r18} OPTIONAL, -- Need Mltm-SK-CounterConfigToAddModList-r19 SEQUENCE (SIZE (1..maxSecurityCellSet-r18)) OF SK-CounterConfigLTM-r19 OPTIONAL, -- Need Nltm-SK-CounterConfigToReleaseList-r19 SEQUENCE (SIZE (1..maxSecurityCellSet-r18)) OF LTM-NoSecurityChangeId-r19 OPTIONAL, -- Need N...}

[0197] In table 6:

[0198] -ltm-ConfigurationSCG: the network does not configure this field in anRRCReconfigurationmessage within anLTM-ConfigIE andConditionalReconfigurationIE. The network does not configure this field in anRRCReconfigurationmessage contained innr-SCGor transmitted on SRB3.

[0199] The LTM candidate configuration / candidate configuration / candidate cell configuration (e.g.,LTE-Candidate) may be related to a candidate (target) cell. The IEs in the LTM candidate configuration / candidate configuration / candidate cell configuration (e.g.,LTE-Candidate) are shown in table 7:

[0200] LTM-Candidate-r18 ::= SEQUENCE {ltm-CandidateId-r18 LTM-CandidateId-r18,ltm-CandidatePCI-r18 PhysCellId OPTIONAL, -- Need Mltm-SSB-Config-r18 LTM-SSB-Config-r18 OPTIONAL, -- Need Mltm-CandidateConfig-r18 OCTET STRING (CONTAINING RRCReconfiguration) OPTIONAL, -- Need Mltm-ConfigComplete-r18 ENUMERATED {true} OPTIONAL, -- Need Rltm-EarlyUL-SyncConfig-r18 OCTET STRING (CONTAINING EarlyUL-SyncConfig-r18) OPTIONAL, -- Need Rltm-EarlyUL-SyncConfigSUL-r18 OCTET STRING (CONTAINING EarlyUL-SyncConfig-r18) OPTIONAL, -- Need Rltm-TCI-Info-r18 LTM-TCI-Info-r18 OPTIONAL, -- Need Mltm-NoResetID-r18 INTEGER (1..maxNrofLTM-Configs-plus1-r18) OPTIONAL, -- Need Mltm-UE-MeasuredTA-ID-r18 INTEGER (1..maxNrofLTM-Configs-plus1-r18) OPTIONAL, -- Need M...,[[ltm-NoSecurityChangeID-r19 LTM-NoSecurityChangeId-r19 OPTIONAL, -- Need Mltm-ExecutionCondition-r19 SetupRelease {LTM-ExecutionConditionList-r19} OPTIONAL, -- Need Mltm-NZP-CSI-RS-ResourceToAddModList-r19 SEQUENCE (SIZE (1..maxNrofNZP-CSI-RS-Resources)) OF NZP-CSI-RS-ResourceOPTIONAL, -- Need Nltm-NZP-CSI-RS-ResourceToReleaseList-r19 SEQUENCE (SIZE (1..maxNrofNZP-CSI-RS-Resources)) OF NZP-CSI-RS-ResourceIdOPTIONAL, -- Need Nltm-NZP-CSI-RS-ResourceSetToAddModList-r19 SEQUENCE (SIZE (1..maxNrofNZP-CSI-RS-ResourceSets)) OF NZP-CSI-RS-ResourceSetOPTIONAL, -- Need Nltm-NZP-CSI-RS-ResourceSetToReleaseList-r19 SEQUENCE (SIZE (1..maxNrofNZP-CSI-RS-ResourceSets)) OF NZP-CSI-RS-ResourceSetIdOPTIONAL, -- Need Nltm-CSI-ReportConfigToAddModList-r19 SEQUENCE (SIZE (1..maxNrofLTM-CSI-ReportConfigurations-r18)) OF LTM-CSI-ReportConfig-r18OPTIONAL, -- Need Nltm-CSI-ReportConfigToReleaseList-r19 SEQUENCE (SIZE (1..maxNrofLTM-CSI-ReportConfigurations-r18)) OF LTM-CSI-ReportConfigId-r18OPTIONAL -- Need Nltm-CSI-IM-ResourceSetToAddModList-r19 SEQUENCE (SIZE (1..maxNrofLTM-CSI-ReportConfigurations-r18)) OF CSI-IM-ResourceSetOPTIONAL, -- Need Nltm-CSI-IM-ResourceSetToReleaseList-r19 SEQUENCE (SIZE (1..maxNrofLTM-CSI-ReportConfigurations-r18)) OF CSI-IM-ResourceSetIdOPTIONAL -- Need N]]}LTM-SSB-Config-r18 ::= SEQUENCE {ssb-Frequency-r18 ARFCN-ValueNR,subcarrierSpacing-r18 SubcarrierSpacing,ssb-Periodicity-r18 ENUMERATED {ms5, ms10, ms20, ms40, ms80, ms160, spare2, spare1} OPTIONAL, -- Need Rssb-PositionsInBurst-r18 CHOICE {shortBitmap BIT STRING (SIZE (4)),mediumBitmap BIT STRING (SIZE (8)),longBitmap BIT STRING (SIZE (64))} OPTIONAL, -- Need Rss-PBCH-BlockPower-r18 INTEGER (-60..50) OPTIONAL, -- Need R...}LTM-NoSecurityChangeId-r19 ::= INTEGER (1..maxNrofLTM-Configs-plus1-r18)

[0201] In table 7:

[0202] -ltm-CandidateId: an ID used to identify an LTM candidate configuration;

[0203] -ltm-CandidateConfig: a configuration of the related candidate cell for LTM, comprisingRRCReconfigurationmessage to be applied when LTM / cell switch is executed;

[0204] -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;

[0205] -ltm-NoResetID: if this field is equal toltm-ServingCellNoResetID, UE may determine that L2 reset is needed upon an LTM cell switch procedure;

[0206] -ltm-NoSecurityChangeID: ID associated with the corresponding candidate cell based on which the UE determines whether a security change is needed or not upon an LTM cell switch procedure. If the network configures this field for one LTM candidate configuration, the network configures also for all LTM candidate configurations withinltm-CandidateToAddModListinLTM-Configand ensures that the UE has stored a value forltm-ServingCellNoSecurityChangeIDwithinVarLTM-ServingCellNoSecurityChange.

[0207] -ltm-UE-MeasuredTA-ID: if this field is equal toltm-ServingCellNoResetID, UE may determine that the UE-based TA measurements are needed;

[0208] -ltmExecutionCondition: this field can only be included within anltm-Configassociated with the MCG;

[0209] -ltm-NZP-CSI-RS-ResourceToAddModList: pool of CSI-RS resources sets which can be referred to inNZP-CSI-RS-ResourceSet;

[0210] -ltm-NZP-CSI-RS-ResourceSetToAddModList: pool of CSI-RS resource set which can be referred to inLTM-CSI-RS-ResourceConfig; and

[0211] -ltm-CSI-ReportConfigToAddModList: configured CSI report settings for LTM.

[0212] The IELTM-ExecutionConditionListmay be used to configure LTM cell switch conditions, and comprises IEs as shown in table 8:

[0213] LTM-ExecutionConditionList-r19 ::= SEQUENCE (SIZE (1..maxNrofLTM-Configs-r18)) OF LTM-ExecutionCondition-r19LTM-ExecutionCondition-r19 ::= SEQUENCE {ltm-CandidateId-r19 LTM-CandidateId-r18,executionCondition-r19 CHOICE {l1-Conditions-r19 LTM-CSI-ReportConfigId-r18,l3-Conditions-r19 SEQUENCE (SIZE (1..2)) OF MeasId} OPTIONAL, -- Need R...}

[0214] For example, when one or more L1 conditions (e.g.,l1-Conditions) are configured, the UE may perform CLTM to a candidate cell based on a beam-level measurement result of at least one beam from a beam set configured for the candidate cell satisfying at least one of the one or more L1 conditions. The one or more L1 conditions may comprise at least one of LTM2 condition (or, event LTM2), LTM3 condition (or, event LTM3), LTM4 condition (or, event LTM4), or LTM5 condition (or, event LTM5).

[0215] The LTM2 condition　(e.g., Beam of SpCell becomes worse than absolute threshold) may include at least one of the following:

[0216] - a measurement result (e.g., reference signal received power (RSRP) / reference signal received quality (RSRQ)) of at least one beam from a beam set for the　SpCell　(or a serving cell)　becomes lower than a configured threshold; and / or

[0217] - the above-mentioned condition persists for at least a　time-to-trigger (TTT).

[0218] The　LTM3 condition　(e.g., Beam of candidate cell becomes amount of offset better than the beam of) may include at least one of the following:

[0219] - a measurement result (e.g., reference signal received power (RSRP) / reference signal received quality (RSRQ)) of at least one beam from a beam set for a　candidate cell　related to the corresponding　measurement object　is better that that of the SpCell by a predefined offset; and / or

[0220] - the above-mentioned condition persists for at least a　time-to-trigger (TTT).

[0221] The　LTM4 condition　(e.g., Beam of candidate cell becomes better than absolute threshold) may include at least one of the following:

[0222] - a measurement result (e.g., reference signal received power (RSRP) / reference signal received quality (RSRQ)) of at least one beam from a beam set for a　candidate cell　related to the corresponding　measurement object　is better than a configured threshold; and / or

[0223] - the above-mentioned condition persists for at least a　time-to-trigger (TTT).

[0224] The　LTM5 condition　(e.g., Beam of SpCell becomes worse than absolute threshold1 AND Beam of candidate cell becomes better than another absolute threshold2) may include at least one of the following:

[0225] - a measurement result (e.g., reference signal received power (RSRP) / reference signal received quality (RSRQ)) of at least one beam from a beam set for the SpCell becomes lower than threshold1, and a measurement result of at least one beam from a beam set for a　candidate cell　related to the corresponding　measurement object　is better than threshold2; and / or

[0226] - the above-mentioned condition persists for at least a　time-to-trigger (TTT).

[0227] For example, when one or more L3 conditions (e.g.,l3-Conditions) are configured, the UE may perform CLTM to a candidate cell based on a cell-level measurement result obtained by applying filtering on measurement results of multiple beams from a beam set configured for the candidate cell satisfying at least one of the one or more L3 conditions.

[0228] The one or more L3 conditions may comprise at least one of A2 condition (or, event A2), A3 condition (or, event A3), A4 condition (or, event A4) or A5 condition (or, event A5).

[0229] The A2 condition　(e.g., Serving becomes worse than threshold) may include at least one of the following:

[0230] - a measurement result (e.g., reference signal received power (RSRP) / reference signal received quality (RSRQ)) of the　SpCell　(or a serving cell) related to the corresponding　measurement object　becomes lower than a configured threshold; and / or

[0231] - the above-mentioned condition persists for at least a　time-to-trigger (TTT).

[0232] The　A3 condition　(e.g., Neighbor becomes offset better than SpCell) may include at least one of the following:

[0233] - a measurement result (e.g., reference signal received power (RSRP) / reference signal received quality (RSRQ)) of a　candidate cell　related to the corresponding　measurement object　is better than the SpCell by a predefined offset; and / or

[0234] - the above-mentioned condition persists for at least a　time-to-trigger (TTT).

[0235] The　A4 condition　(e.g., Neighbor becomes better than threshold) may include at least one of the following:

[0236] - a measurement result (e.g., reference signal received power (RSRP) / reference signal received quality (RSRQ)) of a　candidate cell　related to the corresponding　measurement object　is better than a configured threshold; and / or

[0237] - the above-mentioned condition persists for at least a　time-to-trigger (TTT).

[0238] The　A5 condition　(e.g., SpCell becomes worse than threshold1 and Neighbor becomes better than threshold2) may include at least one of the following:

[0239] - a measurement result (e.g., reference signal received power (RSRP) / reference signal received quality (RSRQ)) of the SpCell becomes lower than threshold1, and a measurement result of a　candidate cell　related to the corresponding　measurement object　is better than threshold2; and / or

[0240] - the above-mentioned condition persists for at least a　time-to-trigger (TTT).

[0241] The　SpCell　may be a serving cell including at least one of a　PCell　or a　PSCell.

[0242] Hereinafter, details of LTM configuration and execution are described.

[0243] I. LTM configuration

[0244] The network configures the UE with one or more LTM candidate configurations within theLTM-ConfigIE.

[0245] Anltm-Configincluded within anRRCReconfigurationmessage received via SRB1 is for LTM on the MCG. It may include an SCG configuration and / orltm-ServingCellNoSecurityChangeID.

[0246] Anltm-Configincluded within anRRCReconfigurationmessage either received via SRB3, or embedded in anRRCReconfigurationmessage received via SRB1 is for LTM on the SCG. It does not include any MCG configuration and does not includeltm-ServingCellNoSecurityChangeID.

[0247] Anltm-ConfigNRDCincluded within anRRCReconfigurationmessage received via SRB1 is for LTM on the SCG. It includes the MCG configuration and may includeltm-ServingCellNoSecurityChangeID.

[0248] In NR-DC, the UE may be configured simultaneously with anltm-Configfor MCG LTM,and anltm-Configfor SCG LTM, or be configured simultaneously with anltm-Configfor MCG LTM,and anltm-ConfigNRDCfor SCG LTM.

[0249] In this case, the following principles apply:

[0250] - the UE maintains independently the twoltm-Config,or theltm-Configand theltm-ConfigNRDC;

[0251] - the UE maintains two independentVarLTM-ServingCellNoResetID, one associated with eachltm-Config,or one associated with theltm-Configand one associated with theltm-ConfigNRDC;

[0252] - the UE maintains two independentVarLTM-ServingCellUE-MeasuredTA-ID, one associated with eachltm-Config,or one associated with theltm-Configand one associated with theltm-ConfigNRDC;

[0253] - the UE independently performs all the LTM configuration and execution for eachltm-Config,or anltm-Configand anltm-ConfigNRDC,and the associatedVarLTM-ServingCellNoResetID,VarLTM-ServingCellUE-MeasuredTA-ID, andVarLTM-ServingCellNoSecurityChange,unless explicitly stated otherwise.

[0254] The UE shall perform the following actions based on the receivedLTM-ConfigIE:

[0255] 1> if the receivedLTM-Configincludesltm-ServingCellNoResetID:

[0256] 2> if the currentVarLTM-ServingCellNoResetIDincludes anltm-ServingCellNoResetID:

[0257] 3> replace theltm-ServingCellNoResetIDvalue withinVarLTM-ServingCellNoResetIDwith the receivedltm-ServingCellNoResetID;

[0258] 2> else:

[0259] 3> store the receivedltm-ServingCellNoResetIDinVarLTM-ServingCellNoResetID;

[0260] 1> if the receivedLTM-Configincludesltm-ServingCellUE-MeasuredTA-ID:

[0261] 2> if the currentVarLTM-ServingCellUE-MeasuredTA-IDincludes anltm-ServingCellUE-MeasuredTA-ID:

[0262] 3> replace theltm-ServingCellUE-MeasuredTA-IDvalue withinVarLTM-ServingCellUE-MeasuredTA-IDwith the receivedltm-ServingCellUE-MeasuredTA-ID;

[0263] 2> else:

[0264] 3> store the receivedltm-ServingCellUE-MeasuredTA-IDinVarLTM-ServingCellUE-MeasuredTA-ID;

[0265] 1> if the receivedLTM-Configincludesltm-ServingCellNoSecurityChangeID:

[0266] 2> if the currentVarLTM-ServingCellNoSecurityChangeincludes anltm-ServingCellNoSecurityChangeID:

[0267] 3> replace theltm-ServingCellNoSecurityChangeIDvalue withinVarLTM-ServingCellNoSecurityChangewith the receivedltm-ServingCellNoSecurityChangeID;

[0268] 2> else:

[0269] 3> store the receivedltm-ServingCellNoSecurityChangeIDinVarLTM-ServingCellNoSecurityChange;

[0270] 1> if the receivedLTM-Configincludes theltm-CandidateToReleaseList:

[0271] 2> perform the LTM candidate configuration release;

[0272] 1> if the receivedLTM-Configincludes theltm-CandidateToAddModList:

[0273] 2> perform the LTM candidate configuration addition or modification;

[0274] 1> reconfigure the UE according to all other fields of the receivedLTM-ConfigIE;

[0275] 1> if the receivedLTM-Configincludes the fieldltm-ServingCellExecutionConditionset tosetup:

[0276] 2> for eachLTM-ExecutionConditionincluded withinltm-ServingCellExecutionCondition:

[0277] 3> if the UE is performing LTM cell switch conditions evaluation based on L1 measurements:

[0278] 4> request lower layers to stop the LTM cell switch conditions evaluation based on L1 measurements for all the LTM candidate configurations;

[0279] 3> if the UE is performing LTM cell switch conditions evaluation based on L3 measurements:

[0280] 4> stop the LTM cell switch conditions evaluation based on L3 measurements for all the LTM candidate configurations;

[0281] 3> ifl3-Conditionsis included withinltm-ServingCellExecutionCondition:

[0282] 4> perform the LTM cell switch conditions evaluation based on L3 measurements as specified in according to the receivedltm-ServingCellExecutionCondition;

[0283] 3> else ifl1-Conditionsis included withinltm-ServingCellExecutionCondition:

[0284] 4> request lower layers to initiate the LTM cell switch conditions evaluation based on L1 measurements according to the received fieldltm-ServingCellExecutionCondition;

[0285] 1> else (ltm-ServingCellExecutionConditionset torelease):

[0286] 2> release the ltm-ServingCellExecutionCondition.

[0287] II. LTM candidate configuration addition / modification

[0288] The UE shall:

[0289] 1> for eachltm-CandidateIdvalueincluded in theltm-CandidateToAddModList:

[0290] 2> if the current UE configuration contains anLTM-Candidatewith theltm-CandidateIdvalue:

[0291] 3> reconfigure the correspondingLTM-Candidatein accordance with the receivedLTM-Candidate;

[0292] 2> else:

[0293] 3> add the receivedLTM-Candidate;

[0294] 2> if theLTM-Candidatewith the receivedltm-CandidateIdvalue includesltm-UE-MeasuredTA-ID:

[0295] 3> if the value ofltm-UE-MeasuredTA-IDis equal to the value ofltm-ServingCellUE-MeasuredTA-IDwithinVarLTM-ServingCellUE-MeasuredTA-ID:

[0296] 4> inform lower layers that the UE is configured with UE-based TA measurements for thisLTM-Candidate;

[0297] 3> else:

[0298] 4> inform lower layers that the UE is not configured with UE-based TA measurements for thisLTM-Candidate;

[0299] 2> else:

[0300] 3> inform lower layers that the UE is not configured with UE-based TA measurements for thisLTM-Candidate.

[0301] III. LTM cell switch conditions evaluation based on L1 measurements

[0302] Upon initiating the LTM cell switch conditions evaluation based on L1 measurements according to the indicated fieldltm-ServingCellExecutionConditionorltm-ExecutionCondition,　the UE shall for the PCell configured for conditional LTM procedure:

[0303] 1> for each entry within theLTM-ExecutionConditionList:

[0304] 2> if theLTM3orLTM5is configured in the correspondingltm-CSI-ReportConfigIdforl1-Conditions:

[0305] 3> consider all beams of LTM candidate cell indicated by theltm-CandidateIdwithin thisLTM-ExecutionConditionand associated withLTM-CSI-ResourceConfigIdwhich is associated with theLTM-CSI-ReportConfigIdforl1-Conditionswithin theLTM-ExecutionConditionto be applicable;

[0306] 3> if the entry condition for the event associated withltm-CSI-ReportConfigIdis fulfilled for TTT for one or more applicable beams, i.e. reference signalling associated withSSB-IndexorNZP-CSI-RS-ResourceIDin theLTM-CSI-ResourceConfigassociated with theLTM-CSI-ReportConfig, for the measurement from lower layer during TTT defined for this event;

[0307] 4> consider the event associated withLTM-CSI-ReportConfigIdto be fulfilled for theltm-CandidateIdassociated withLTM-CSI-ReportConfigId;

[0308] 4> perform the LTM cell switch execution procedure for the LTM candidate configuration associated withltm-CandidateId.

[0309] IV. LTM cell switch conditions evaluation based on L3 measurements

[0310] The UE shall:

[0311] 1> for each entry within theLTM-ExecutionConditionListwhich has thel3-Conditionsconfigured:

[0312] 2> for eachmeasIdindicated in thel3-Conditionswhich has a correspondingmeasIdin theVarMeasConfigassociated with the MCGmeasConfig:

[0313] 3> if thecondEventIdrelated to thismeasIdis associated withcondEventA3orcondEventA5, and if the entry condition applicable for this event is fulfilled for theltm-CandidatePCIrelated to theltm-CandidateIdfor all measurements after layer 3 filtering taken during the correspondingtimeToTriggerdefined for this event:

[0314] 4> consider the event associated to thismeasIdto be fulfilled for theltm-CandidateIdassociated to themeasId;

[0315] 3> if thecondEventIdrelated to thismeasIdis associated withcondEventA3orcondEventA5, and if the leaving condition applicable for this event is fulfilled for theltm-CandidatePCIrelated to theltm-CandidateIdfor all measurements after layer 3 filtering taken during the correspondingtimeToTriggerdefined for this event:

[0316] 4> consider the event associated to thismeasIdto be not fulfilled for theltm-CandidateIdassociated to themeasId;

[0317] 1> if event(s) associated with allmeasId(s)for anltm-CandidateIdwithin theLTM-ExecutionConditionListIE are fulfilled:

[0318] 2> inform lower layers that an event based on L3 measurements to perform an LTM cell switch procedure is fulfilled;

[0319] 2> perform the LTM cell switch execution procedure for the LTM candidate configuration associated to theltm-CandidateId.

[0320] V. LTM cell switch execution

[0321] Upon the indication by lower layers that an LTM cell switch procedure is triggered, or upon performing LTM cell switch following cell selection performed while timer T311 was running, or upon the fulfilment of LTM cell switch execution conditions, the UE shall:

[0322] 1> if this procedure is triggered due to fulfilment of LTM cell switch execution conditions:

[0323] 2> if more than one LTM candidate configuration has triggered this procedure:

[0324] 3> select one of the LTM candidate configurations as the selected cell for the LTM cell switch execution;

[0325] 1> if the LTM cell switch is triggered on the MCG; or

[0326] 1> if the LTM cell switch is triggered on the SCG and the LTM candidate configuration to be applied is configured vialtm-ConfigNRDC:

[0327] 2> release / clear all current dedicated and common radio configurations which have neither been received via SRB1 withinmrdc-SecondaryCellGroup, nor via SRB3 except for the following:

[0328] - the radio bearer configuration (configured viaRadioBearerConfig)

[0329] - thelogicalChannelIdentityandlogicalChannelIdentityExtof RLC bearers configured inRLC-BearerConfigand the associated RLC entities, their state variables, buffers, and timers, except for triggering the associated RLC entities to reset the variable RETX_COUNT its initial value;

[0330] - thebh-LogicalChannelIdentityof BH RLC channels configured inBH-RLC-ChannelConfigand the associated RLC entities, their state variables, buffers, and timers, except for triggering the associated RLC entities to reset the variable RETX_COUNT its initial value;

[0331] - the UE variablesVarLTM-ServingCellNoResetID,VarLTM-ServingCellUE-MeasuredTA-ID, andVarLTM-ServingCellNoSecurityChange;

[0332] - theltm-Configandltm-ConfigNRDC(if configured);

[0333] - the MCG C-RNTI;

[0334] - the AS security configurations associated with the master key;

[0335] - the logged measurement configuration;

[0336] - thesuccessHO-Config;

[0337] 3> if the LTM cell switch is triggered on the SCG and the LTM candidate configuration to be applied is configured vialtm-ConfigNRDC:

[0338] - theServingCellConfigCommonof the PCell;

[0339] 1> if the LTM cell switch is triggered on the SCG:

[0340] 2> release / clear all current dedicated and common radio configurations which have been received either via SRB1 withinmrdc-SecondaryCellGroup, or via SRB3 except for the following:

[0341] - the radio bearer configuration (configured viaRadioBearerConfigIE)

[0342] - thelogicalChannelIdentityandlogicalChannelIdentityExtof RLC bearers configured inRLC-BearerConfigand the associated RLC entities, their state variables, buffers, and timers, except for triggering the associated RLC entities to reset the variable RETX_COUNT its initial value;

[0343] - thebh-LogicalChannelIdentityof BH RLC channels configured inBH-RLC-ChannelConfigand the associated RLC entities, their state variables, buffers, and timers, except for triggering the associated RLC entities to reset the variable RETX_COUNT its initial value;

[0344] - the UE variablesVarLTM-ServingCellNoResetIDandVarLTM-ServingCellUE-MeasuredTA-ID;

[0345] - theltm-Config;

[0346] - the AS security configurations associated with the secondary key;

[0347] 1> for each SRB / DRB in the current UE configuration:

[0348] 2> if the LTM cell switch is triggered on the MCG and the SRB / DRB using the master key; or

[0349] 2> if the LTM cell switch is triggered on the SCG and the SRB / DRB using the secondary key:

[0350] 3> keep the associated PDCP and SDAP entities, their state variables, buffers and timers;

[0351] 3> release all fields related to the SRB / DRB configuration except forsrb-Identityanddrb-Identity;

[0352] 3> apply the default SRB configuration for the corresponding SRB;

[0353] For all radio bearers and RLC bearers included in the LTM candidate configuration to be applied at an LTM cell switch execution (i.e., as derived from the LTM reference configuration and the LTM candidate configuration), even if those radio bearers and RLC bearers were configured before the LTM cell switch execution, the network includes fields as specified for the initial setup of radio bearers and RLC bearers and sets the values previously stored by the UE for the fields that cannot be modified according to presence conditions or field descriptions.

[0354] 1> apply the default L1 parameter values as specified in corresponding physical layer specifications except for the parameters for which values are provided in SIB1;

[0355] 1> use the default values for timers T310, T311 and constants N310, N311 associated with the cell group(s) for which theRRCReconfigurationmessage is applied due to the triggered LTM cell switch procedure, where T310, N310, and N311 are for both MCG and SCG, and T311 is only for the MCG;

[0356] 1> apply the default MAC Cell Group configuration for the cell group(s) for which theRRCReconfigurationmessage is applied due to the triggered LTM cell switch procedure;

[0357] 1> if the value ofltm-NoSecurityChangeIDcontained in theLTM-CandidateIE inltm-Configorltm-ConfigNRDCindicated by lower layers or for the selected cell is not equal to the value ofltm-ServingCellNoSecurityChangewithinVarLTM-ServingCellNoSecurityChange:

[0358] 2> for eachlogicalChannelIdentityandlogicalChannelIdentityExtthat is part of the current UE configuration for the cell group for which the LTM cell switch procedure is triggered:

[0359] 3> after the end of this procedure, re-establish the corresponding RLC entity, after applying the LTM configuration inltm-CandidateConfigwithin theLTM-CandidateIE inltm-Configorltm-ConfigNRDC;

[0360] 2> for eachbh-LogicalChannelIdentitythat is part of the current UE configuration for the cell group for which the LTM cell switch procedure is triggered:

[0361] 3> after the end of this procedure, re-establish the corresponding RLC entity, after applying the LTM configuration inltm-CandidateConfigwithin the LTM-Candidate IE inltm-Configorltm-ConfigNRDC;

[0362] 2> if the LTM cell switch is triggered on the MCG:

[0363] 3> update the master security key by performing the AS security key update procedure;

[0364] 2> else if the LTM cell switch is triggered on the SCG:

[0365] 3> consider the firstsk-Countervalue in theltm-SK-Counterswithin theVarLTM-ServingCellNoSecurityChangeassociated to the fieldltm-NoSecurityChangeIDas the selectedsk-Countervalue, and update the secondary key by performing security key update procedure;

[0366] 3> remove the selectedsk-Countervalue from theltm-SK-Counterswithin theVarLTM-ServingCellNoSecurityChange;

[0367] 2> at the end of the procedure, for eachdrb-Identityvalue that is part of the current UE configuration:

[0368] 3> if the LTM cell switch is triggered on the MCG; or

[0369] 3> if the LTM cell switch is triggered on the SCG and this DRB is using the secondary key; or

[0370] 3> if the LTM cell switch is triggered on the SCG and thekeyToUsefor this DRB is changed:

[0371] 4> if the PDCP entity of this DRB is not configured withcipheringDisabled:

[0372] 5> configure the PDCP entity with the ciphering algorithm and KUPenc key associated with the master key (KgNB) or secondary key (S-KgNB), as indicated inkeyToUse, i.e. the ciphering configuration shall be applied to all subsequent PDCP PDUs received and sent by the UE;

[0373] 4> if the PDCP entity of this DRB is configured withintegrityProtection:

[0374] 5> configure the PDCP entity with the integrity protection algorithms according tosecurityConfigand apply the KUPint key associated with the master key (KgNB) or the secondary key (S-KgNB) as indicated inkeyToUse;

[0375] 4> ifdrb-ContinueROHCis included inpdcp-Config:

[0376] 5> indicate to lower layer thatdrb-ContinueROHCis configured;

[0377] 4> ifdrb-ContinueEHC-DLis included inpdcp-Config:

[0378] 5> indicate to lower layer thatdrb-ContinueEHC-DLis configured;

[0379] 4> ifdrb-ContinueEHC-ULis included inpdcp-Config:

[0380] 5> indicate to lower layer thatdrb-ContinueEHC-ULis configured;

[0381] 4> ifdrb-ContinueUDCis included inpdcp-Config:

[0382] 5> indicate to lower layer thatdrb-ContinueUDCis configured;

[0383] 4> re-establish the PDCP entity of this DRB;

[0384] 3> else if LTM cell switch is triggered on the SCG and this DRB is using the master key:

[0385] 4> if the RLC entity of an RLC bearer associated with this DRB is re-established or released during LTM cell switch execution:

[0386] 5> if this DRB is an AM DRB:

[0387] 6> after the end of this procedure, trigger the PDCP entity of this DRB to perform data recovery, after applying the LTM configuration inltm-CandidateConfigwithinLTM-CandidateIE inltm-Configorltm-ConfigNRDC;

[0388] 2> at the end of the procedure, for eachsrb-Identityvalue that is part of the current UE configuration:

[0389] 3> if the LTM cell switch is triggered on the MCG; or

[0390] 3> if the LTM cell switch is triggered on the SCG and the SRB is using the secondary key:

[0391] 4> configure the PDCP entity to apply the integrity protection algorithm and KRRCint key associated with the master key (KgNB) or the secondary key (S-KgNB), as indicated inkeyToUse, i.e. the integrity protection configuration 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;

[0392] 4> configure the PDCP entity to apply the ciphering algorithm and KRRCenc key associated with the master key (KgNB) or the secondary key (S-KgNB) as indicated inkeyToUse, i.e. the ciphering configuration 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;

[0393] 4> re-establish the PDCP entity of this SRB;

[0394] 2> if the value of fieldltm-NoSecurityChangeIDcontained in theLTM-CandidateIE inltm-Configorltm-ConfigNRDCindicated by lower layers or for the selected cell is not equal to the value ofltm-ServingCellNoSecurityChangeIDwithinVarLTM-ServingCellNoSecurityChange:

[0395] 3> replace the value ofltm-ServingCellNoSecurityChangeIDinVarLTM-ServingCellNoSecurityChangewith the value ofltm-NoSecurityChangeIDin theLTM-Candidateinltm-Configorltm-ConfigNRDCindicated by lower layers or for the selected cell;

[0396] 1> else if the fieldltm-NoSecurityChangeIDis not configured for theLTM-CandidateIE inltm-Configorltm-ConfigNRDCindicated by lower layers and if the UE does not have any value stored ofltm-ServingCellNoSecurityChangeIDwithinVarLTM-ServingCellNoSecurityChangeID; or

[0397] 1> if theLTM-CandidateIE inltm-Configorltm-ConfigNRDCindicated by lower layers or for the selected cell does not contain the fieldltm-NoResetIDand if the UE does not have any value stored ofltm-ServingCellNoResetIDwithinVarLTM-ServingCellNoResetID; or

[0398] 1> if the value of fieldltm-NoResetIDcontained within theLTM-CandidateIE inltm-Configorltm-ConfigNRDCindicated by lower layers or for the selected cell is not equal to the value ofltm-ServingCellNoResetIDwithinVarLTM-ServingCellNoResetID:

[0399] 2> for eachlogicalChannelIdentityandlogicalChannelIdentityExtthat is part of the current UE configuration for the cell group for which the LTM cell switch procedure is triggered:

[0400] 3> ifservedRadioBeareris set todrb-Identity:

[0401] 4> after the end of this procedure, re-establish the corresponding RLC entity, after applying the LTM configuration inltm-CandidateConfigwithin theLTM-CandidateIE inltm-Configorltm-ConfigNRDC;

[0402] 2> for eachbh-LogicalChannelIdentitythat is part of the current UE configuration for the cell group for which the LTM cell switch procedure is triggered:

[0403] 3> after the end of this procedure, re-establish the corresponding RLC entity, after applying the LTM configuration inltm-CandidateConfigwithin the LTM-Candidate IE inltm-Configorltm-ConfigNRDC;

[0404] 2> for eachdrb-Identityvalue that is part of the current UE configuration:

[0405] 3> if this DRB is an AM DRB:

[0406] 4> after the end of this procedure, trigger the PDCP entity of this DRB to perform data recovery, after applying the LTM configuration inltm-CandidateConfigwithinLTM-CandidateIE inltm-Configorltm-ConfigNRDC;

[0407] 2> if the value of fieldltm-NoResetIDcontained within theLTM-CandidateIE inltm-Configorltm-ConfigNRDCindicated by lower layers or for the selected cell is not equal to the value ofltm-ServingCellNoResetIDwithinVarLTM-ServingCellNoResetID:

[0408] 3> replace the value ofltm-ServingCellNoResetIDinVarLTM-ServingCellNoResetIDwith the value ofltm-NoResetIDin theLTM-Candidateinltm-Configorltm-ConfigNRDCindicated by lower layers or for the selected cell;

[0409] 1> if theLTM-CandidateIE inltm-Configorltm-ConfigNRDCindicated by lower layers or for the selected cell contains the fieldltm-UE-MeasuredTA-ID:

[0410] 2> if the value ofltm-UE-MeasuredTA-IDis not equal to the value ofltm-ServingCellUE-MeasuredTA-IDwithinVarLTM-ServingCellUE-MeasuredTA-ID:

[0411] 3> replace the value ofltm-ServingCellUE-MeasuredTA-IDinVarLTM-ServingCellUE-MeasuredTA-IDwith the value received withinltm-UE-MeasuredTA-ID;

[0412] 3> for eachLTM-CandidateIE inltm-Configorltm-ConfigNRDCthat includes theLTM-CandidateIE indicated by lower layers or for the selected cell:

[0413] 4> if the value ofltm-UE-MeasuredTA-IDwithinLTM-CandidateIE is equal to the value ofltm-ServingCellUE-MeasuredTA-IDwithinVarLTM-ServingCellUE-MeasuredTA-ID:

[0414] 5> inform lower layers that the UE is configured with UE-based TA measurements for theLTM-Candidate;

[0415] 4> else:

[0416] 5> inform lower layers that the UE is not configured with UE-based TA measurements for theLTM-Candidate;

[0417] The UE is not expected to perform UE-based TA measurements for an SpCell.

[0418] 1> ifltm-ConfigCompleteis not included within theLTM-CandidateIE inltm-Configorltm-ConfigNRDCindicated by lower layers or for the selected cell:

[0419] 2> considerltm-ReferenceConfigurationinltm-Configorltm-ConfigNRDC, associated with the cell group for which the LTM cell switch procedure is triggered, to be the current UE configuration for the fields and configurations to be released by the actions above in this procedure;

[0420] 2> ifmeasConfigis included withinltm-ReferenceConfigurationinltm-Configorltm-ConfigNRDC;

[0421] 3> perform the measurement configuration procedure by considering themeasConfigwithinltm-ReferenceConfigurationinltm-Configorltm-ConfigNRDCas the receivedmeasConfig:

[0422] 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, unless specified otherwise in this clause.

[0423] 1> if the LTM cell switch is triggered by an indication from lower layers:

[0424] 2> apply theRRCReconfigurationmessage inltm-CandidateConfigwithinLTM-CandidateIE inltm-Configorltm-ConfigNRDCidentified by the LTM candidate configuration identity received from lower layers;

[0425] 1> else (LTM cell switch triggered upon cell selection performed while timer T311 was running or upon the fulfilment of LTM cell switch execution conditions):

[0426] 2> apply theRRCReconfigurationmessage inltm-CandidateConfigwithinLTM-CandidateIE inltm-Configrelated to the LTM candidate configuration identity for the selected cell;

[0427] 1> if the LTM cell switch is triggered on the MCG:

[0428] 2> release the radio bearer(s) using the master key and the MCG logical channel(s) that were part of the UE configuration before this LTM cell switch procedure but not part of the LTM candidate configuration either indicated by lower layers or for the selected cell, or the LTM reference configuration (in case the LTM candidate configuration does not includeltm-ConfigComplete);

[0429] 1> else, if the LTM cell switch is triggered on the SCG:

[0430] 2> release the radio bearer(s) using the secondary key and the SCG logical channel(s) that were part of the UE configuration before this LTM cell switch procedure but not part of the LTM candidate configuration either indicated by lower layers or for the selected cell, or the LTM reference configuration (in case the LTM candidate configuration does not includeltm-ConfigComplete);

[0431] 1> ifltm-ExecutionConditionis configured within theLTM-CandidateIE for the selected LTM candidate configuration:

[0432] 2> if the fieldl3-Conditionsis included withinltm-ExecutionCondition:

[0433] 3> perform the LTM cell switch conditions evaluation based on L3 measurements according to the receivedltm-ExecutionConditiononce this procedure is completed;

[0434] 2> else if the fieldl1-Conditionsis included withinltm-ExecutionCondition:

[0435] 3> request lower layers to initiate the LTM cell switch conditions evaluation based on L1 measurements according to the received fieldltm-ExecutionConditiononce this procedure is completed.

[0436] Whenltm-ConfigCompleteis not included for an LTM candidate configuration, before an LTM cell switch is triggered a UE implementation may generate and store anRRCReconfigurationmessage by applying the received LTM candidate configuration on top of the LTM reference configuration, and the storedRRCReconfigurationmessage is applied when the LTM cell switch is triggered. It is up to the UE to ensure that the RRC reconfiguration applied at the time of LTM cell switch is in accordance with the latest LTM reference configuration and LTM candidate configuration.

[0437] Meanwhile, UE can be configured with a mixture of intra-CU and inter-CU candidate LTM cells, based on at least one of the followings:

[0438] - inter-CU LTM also supports mixture of subsequent inter-CU LTM and subsequent intra-CU LTM after an inter-CU and / or intra-CU LTM switch; or

[0439] - UE can be configured with a mixture of intra-CU and inter-CU candidate LTM cells and irrespective of how the UE is configured with this mixture, UE measurement and reporting procedures will be the same for both intra-CU and inter-CU candidate LTM cells.

[0440] For subsequent inter-CU LTM cell switches, a new RRC ID (i.e.,ltm-NoSecurityChangeIDandltm-ServingCellNoSecurityChangeID) are introduced based on:

[0441] - If the security key update is required, the UE shall perform MAC reset, RLC re-establishment and / or PDCP re-establishment. As baseline, a new RRC ID may be introduced. For example, if the new RRC ID is different for the source cell and the target cell, the UE performs PDCP re-establishment, including security key update.

[0442] For conditional LTM (CLTM), execution conditions may be configured on the mixture of intra-CU and inter-CU candidate LTM cells. For example, UE may be configured with a single LTM configuration for inter-CU LTM, intra-CU LTM, and / or intra-CU conditional LTM.

[0443] If UE autonomously executes the LTM cell switch based on the fulfilment of execution condition(s), the UE may execute inter-CU CLTM cell switch (i.e., invalid CLTM cell switch) because there are no UE actions for evaluating whether the CLTM cell switch is inter-CU CLTM or intra-CU CLTM. Due to the execution of invalid CLTM cell switch, the UE may undergo a mobility failure and consequently, the UE interruption may increase.

[0444] In order to prevent triggering inter-CU CLTM and / or invalid CLTM cell switch, network should reconfigure CLTM execution conditions whenever inter-CU LTM cell switch is executed based on the existing LTM cell switch execution procedure. This may result in network signalling overhead.

[0445] Therefore, the present disclosure provides various embodiments for preventing invalid cell switch.

[0446] FIG. 11 shows an example of a method performed by a UE for preventing invalid cell switch according to various embodiments of the present disclosure.

[0447] Referring to FIG. 11, in step S1101, the UE may receive a candidate configuration for cell switch related to a first candidate cell. The candidate configuration may comprise: a configuration of the first candidate cell; one or more execution conditions for cell switch to the first candidate cell; and an identifier (ID) related to the first candidate cell.

[0448] In step S1103, the UE may evaluate the one or more execution conditions for cell switch to the first candidate cell.

[0449] In step S1105, the UE may apply the configuration of the first candidate cell based on: i) at least one of the one or more execution conditions being fulfilled; and ii) the ID related to the first candidate cell being equal to an ID related to a serving cell.

[0450] According to various embodiments, the ID related to the first candidate cell and the ID related to the serving cell may comprise an ID related to the first candidate cell for determining whether a security change is needed or not upon a cell switch procedure.

[0451] According to various embodiments, the UE may perform the security change based on the ID related to the first candidate cell being not equal to the ID related to the serving cell.

[0452] According to various embodiments, the security change may comprise at least one of: performing a radio link control (RLC) re-establishment; performing a packet data convergence protocol (PDCP) re-establishment; updating a master security key; updating a secondary security key; applying a ciphering configuration; applying a integrity protection configuration; or performing a data recovery.

[0453] According to various embodiments, the cell switch procedure may be initiated based on at least one of the one or more execution conditions being fulfilled. The cell switch procedure may comprise applying the configuration of the first candidate cell.

[0454] According to various embodiments, the ID related to the first candidate cell may be equal to the ID related to the serving cell based on the first candidate cell and the serving cell being related to a same central unit (CU). The ID related to the first candidate cell may not be equal to the ID related to the serving cell based on the first candidate cell and the serving cell being related to different CUs.

[0455] According to various embodiments, the UE may evaluate the one or more execution conditions for cell switch to the first candidate cell based on the ID related to the first candidate cell being equal to the ID related to the serving cell.

[0456] According to various embodiments, the ID related to the serving cell may be received from the serving cell via a cell switch configuration comprising the candidate configuration related to the first candidate cell.

[0457] According to various embodiments, the UE may receive a cell switch configuration comprising the candidate configuration related to the first candidate cell and a candidate configuration related to a second candidate cell. The candidate configuration related to the first candidate cell may further comprise one or more execution conditions for subsequent cell switch to the second candidate cell. The candidate configuration related to the second candidate cell may comprise: a configuration of the second candidate cell; and an ID related to the second candidate cell.

[0458] According to various embodiments, after applying the configuration of the first candidate cell, the UE may evaluate the one or more execution conditions for subsequent cell switch to the second candidate cell. The UE may apply the configuration of the second candidate cell based on: i) at least one of the one or more execution conditions for subsequent cell switch being fulfilled; and ii) the ID related to the second candidate cell being equal to the ID related to the first candidate cell.

[0459] According to various embodiments, after applying the configuration of the first candidate cell, the UE may receive a cell switch command comprising an ID of the candidate configuration related to the second candidate cell. The UE may apply the configuration of the second candidate cell, regardless of whether the ID related to the second candidate cell is equal to the ID related to the first candidate cell or not.

[0460] According to various embodiments, after applying the configuration of the first candidate cell, the UE may select a cell based on detecting a failure. The UE may apply the configuration of the second candidate cell based on the selected cell being the second candidate cell, regardless of whether the ID related to the second candidate cell is equal to the ID related to the first candidate cell or not.

[0461] FIG. 12 shows an example of a signal flow between UE and network node for preventing invalid cell switch according to various embodiments of the present disclosure.

[0462] Referring to FIG. 12, in step S1201, the network node may transmit, to the UE, a candidate configuration for cell switch related to a first candidate cell. The candidate configuration may comprise: a configuration of the first candidate cell; one or more execution conditions for cell switch to the first candidate cell; and an identifier (ID) related to the first candidate cell.

[0463] In step S1203, the UE may evaluate the one or more execution conditions for cell switch to the first candidate cell.

[0464] In step S1205, the UE may apply the configuration of the first candidate cell based on: i) at least one of the one or more execution conditions being fulfilled; and ii) the ID related to the first candidate cell being equal to an ID related to a serving cell.

[0465] Hereinafter, detailed descriptions regarding a prevention of invalid cell switch are described.

[0466] According to various embodiments of the present disclosure, method and apparatus for preventing invalid CLTM cell switch execution based on ID comparison are provided.

[0467] Upon a fulfilment of CLTM cell switch execution conditions, the UE may perform the CLTM cell switch execution if the ID associated with the target cell (e.g.,ltm-NoSecurityChangeID) is equal to the ID associated with the source cell / serving cell (e.g.,ltm-ServingCellNoSecurityChangeID).

[0468] As an alternative, for evaluating CLTM execution conditions, the UE may select the reference signals associated with the candidate cells whose ID (e.g.,ltm-NoSecurityChangeIDfor each candidate cell) is equal to the ID associated with the current serving cell (e.g.,ltm-ServingCellNoSecurityChangeID). For example, after successful inter-CU LTM cell switch, the UE RRC layer may indicate to the UE MAC layer that the inter-CU LTM cell switch is successfully completed. Based on the indication, the UE MAC layer may perform CLTM evaluation for the candidate cells whose ID is same as the ID associated with the new serving cell.

[0469] UE may not execute the LTM cell switch if the value ofltm-NoSecurityChangeIDis not equal to that ofltm-ServingCellNoSecurityChangeID. Examples thereof are provided below.

[0470] 1. First example of LTM cell switch execution procedure

[0471] Upon the indication by lower layers that an LTM cell switch procedure is triggered, or upon performing LTM cell switch following cell selection performed while timer T311 was running, or upon the fulfilment of CLTM cell switch conditions, the UE shall:

[0472] 1> if this procedure is triggered due to fulfilment of LTM cell switch conditions and if the value of fieldltm-NoSecurityChangeIDcontained within theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers is equal to the value ofltm-ServingCellNoSecurityChangeIDwithinVarLTM-ServingCellNoSecurityChangeID:

[0473] 2> if more than one LTM candidate configuration has triggered this procedure:

[0474] 3> select one of the LTM candidate configurations as the selected cell for the LTM cell switch execution;

[0475] 2> stop the LTM conditions evaluation (based on L1 and / or L3 measurements), if any, for all the LTM candidate configurations associated with the cell group for which the LTM cell switch procedure is triggered;

[0476] 2> if theLTM-CandidateIE for the selected LTM candidate configuration includes the fieldcltm-ExecutionConditions(or,ltm-ExecutionConditionList):

[0477] 3> if the fieldl3-Conditionsis included withincltm-ExecutionConditions:

[0478] 4> perform the LTM cell switch conditions evaluation based on L3 measurements according to the receivedcltm-ExecutionConditions;

[0479] 3> else if the fieldl1-Conditionsis included withincltm-ExecutionConditions:

[0480] 4> inform lower layers to initiate the LTM cell switch conditions evaluation based on L1 measurements according to the received fieldcltm-ExecutionConditions.

[0481] 1> if the LTM cell switch is triggered on the MCG; or

[0482] 1> if the LTM cell switch is triggered on the SCG and the UE has anltm-Configassociated with the MCG:

[0483] 2> release / clear all current dedicated and common radio configurations which have neither been received via SRB1 withinmrdc-SecondaryCellGroup, nor via SRB3 except for the following:

[0484] - the radio bearer configuration (configured viaRadioBearerConfig);

[0485] - thelogicalChannelIdentityandlogicalChannelIdentityExtof RLC bearers configured inRLC-BearerConfigand the associated RLC entities, their state variables, buffers, and timers, except for triggering the associated RLC entities to reset the variable RETX_COUNT its initial value;

[0486] - thebh-LogicalChannelIdentityof BH RLC channels configured inBH-RLC-ChannelConfigand the associated RLC entities, their state variables, buffers, and timers, except for triggering the associated RLC entities to reset the variable RETX_COUNT its initial value;

[0487] - the UE variablesVarLTM-ServingCellNoResetIDandVarLTM-ServingCellUE-MeasuredTA-ID;

[0488] - theltm-Configandltm-ConfigSCG(if configured);

[0489] - the MCG C-RNTI;

[0490] - the AS security configurations associated with the master key;

[0491] - the logged measurement configuration;

[0492] 1> if the LTM cell switch is triggered on the SCG:

[0493] 2> release / clear all current dedicated and common radio configurations which have been received either via SRB1 withinmrdc-SecondaryCellGroup, or via SRB3 except for the following:

[0494] - the radio bearer configuration (configured viaRadioBearerConfigIE);

[0495] - thelogicalChannelIdentityandlogicalChannelIdentityExtof RLC bearers configured inRLC-BearerConfigand the associated RLC entities, their state variables, buffers, and timers, except for triggering the associated RLC entities to reset the variable RETX_COUNT its initial value;

[0496] - thebh-LogicalChannelIdentityof BH RLC channels configured inBH-RLC-ChannelConfigand the associated RLC entities, their state variables, buffers, and timers, except for triggering the associated RLC entities to reset the variable RETX_COUNT its initial value;

[0497] - the UE variablesVarLTM-ServingCellNoResetIDandVarLTM-ServingCellUE-MeasuredTA-ID;

[0498] - theltm-Config;

[0499] - the AS security configurations associated with the secondary key;

[0500] 1> for each SRB / DRB in the current UE configuration:

[0501] 2> if the LTM cell switch is triggered on the MCG and the SRB / DRB using the master key; or

[0502] 2> if the LTM cell switch is triggered on the SCG and the SRB / DRB using the secondary key:

[0503] 3> keep the associated PDCP and SDAP entities, their state variables, buffers and timers;

[0504] 3> release all fields related to the SRB / DRB configuration except forsrb-Identityanddrb-Identity;

[0505] 1> apply the default L1 parameter values as specified in corresponding physical layer specifications except for the parameters for which values are provided in SIB1;

[0506] 1> use the default values for timers T310, T311 and constants N310, N311 associated with the cell group for which the LTM cell switch procedure is triggered, where T310, N310, and N311 are for both MCG and SCG, and T311 is only for the MCG;

[0507] 1> apply the default MAC Cell Group configuration for the cell group for which the LTM cell switch procedure is triggered;

[0508] 1> for eachsrb-Identityin the current UE configuration:

[0509] 2> apply the default SRB configuration for the corresponding SRB;

[0510] 1> if the fieldltm-NoSecurityChangeIDis configured for theLTM-CandidateIE and if the UE does not have any value stored ofltm-ServingCellNoSecurityChangeIDwithinVarLTM-ServingCellNoSecurityChangeID; or

[0511] 1> if the value of fieldltm-NoSecurityChangeIDcontained within theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell is not equal to the value ofltm-ServingCellNoSecurityChangeIDwithinVarLTM-ServingCellNoSecurityChangeID:

[0512] 2> if the LTM cell switch is triggered on the MCG:

[0513] 3> update the master security key by performing the AS security key update procedure;

[0514] 2> else if the LTM cell switch is triggered on the SCG:

[0515] 3> consider the firstsk-Countervalue in theltm-SK-Counterswithin theVarLTM-ServingCellNoSecurityChangeIDas the selectedsk-Countervalue, and perform security key update procedure;

[0516] 3> remove the selectedsk-Countervalue from theltm-SK-Counterswithin theVarLTM-ServingCellNoSecurityChangeID;

[0517] 2> for eachdrb-Identityvalue that is part of the current UE configuration:

[0518] 3> if the PDCP entity of this DRB is not configured withcipheringDisabled:

[0519] 4> configure the PDCP entity with the ciphering algorithm and KUPenckey associated with the master key (KeNB / KgNB) or secondary key (S-KgNB / S-KeNB), as indicated inkeyToUse, i.e. the ciphering configuration shall be applied to all subsequent PDCP PDUs received and sent by the UE;

[0520] 3> if the PDCP entity of this DRB is configured withintegrityProtection:

[0521] 4> configure the PDCP entity with the integrity protection algorithms according tosecurityConfigand apply the KUPintkey associated with the master key (KeNB / KgNB) or the secondary key (S-KgNB) as indicated inkeyToUse;

[0522] 3> if drb-ContinueROHC is included in pdcp-Config:

[0523] 4> indicate to lower layer thatdrb-ContinueROHCis configured;

[0524] 3> if drb-ContinueEHC-DL is included in pdcp-Config:

[0525] 4> indicate to lower layer thatdrb-ContinueEHC-DLis configured;

[0526] 3> if drb-ContinueEHC-UL is included in pdcp-Config:

[0527] 4> indicate to lower layer thatdrb-ContinueEHC-ULis configured;

[0528] 3> if drb-ContinueUDC is included in pdcp-Config:

[0529] 4> indicate to lower layer thatdrb-ContinueUDCis configured;

[0530] 3> re-establish the PDCP entity of this DRB;

[0531] 2> for eachsrb-Identityvalue that is part of the current UE configuration:

[0532] 3> if the UE has selected a newsk-Countervalue due to this LTM cell switch procedure:

[0533] 4> configure the PDCP entity to apply the integrity protection algorithm and KRRCintkey associated with the master key (KeNB / KgNB) or the secondary key (S-KgNB), as indicated inkeyToUse, i.e. the integrity protection configuration 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;

[0534] 4> configure the PDCP entity to apply the ciphering algorithm and KRRCenckey associated with the master key (KeNB / KgNB) or the secondary key (S-KgNB) as indicated inkeyToUse, i.e. the ciphering configuration 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;

[0535] 4> re-establish the PDCP entity of this SRB;

[0536] 3> else:

[0537] 4> trigger the PDCP entity to perform SDU discard;

[0538] 2> if the value of fieldltm-NoSecurityChangeIDcontained within theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell is not equal to the value ofltm-ServingCellNoSecurityChangeIDwithinVarLTM-ServingCellNoSecurityChangeID:

[0539] 3> replace the value ofltm-ServingCellNoSecurityChangeIDinVarLTM-ServingCellNoSecurityChangeIDwith the value ofltm-NoSecurityChangeIDin theLTM-Candidateinltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell;

[0540] 1> if theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell does not contain the fieldltm-NoResetIDand if the UE does not have any value stored ofltm-ServingCellNoResetIDwithinVarLTM-ServingCellNoResetID; or

[0541] 1> if the value of fieldltm-NoResetIDcontained within theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell is not equal to the value ofltm-ServingCellNoResetIDwithinVarLTM-ServingCellNoResetID:

[0542] 2> for eachlogicalChannelIdentityandlogicalChannelIdentityExtthat is part of the current UE configuration for the cell group for which the LTM cell switch procedure is triggered:

[0543] 3> ifservedRadioBeareris set todrb-Identity:

[0544] 4> after the end of this procedure, re-establish the corresponding RLC entity, after applying the LTM configuration inltm-CandidateConfigwithin theLTM-CandidateIE inltm-Configorltm-ConfigSCG;

[0545] 2> for eachbh-LogicalChannelIdentitythat is part of the current UE configuration for the cell group for which the LTM cell switch procedure is triggered:

[0546] 3> after the end of this procedure, re-establish the corresponding RLC entity, after applying the LTM configuration inltm-CandidateConfigwithin the LTM-Candidate IE inltm-Configorltm-ConfigSCG;

[0547] 2> for eachdrb-Identityvalue that is part of the current UE configuration:

[0548] 3> if this DRB is an AM DRB:

[0549] 4> after the end of this procedure, trigger the PDCP entity of this DRB to perform data recovery, after applying the LTM configuration inltm-CandidateConfigwithinLTM-CandidateIE inltm-Configorltm-ConfigSCG;

[0550] 2> if the value of fieldltm-NoResetIDcontained within theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell is not equal to the value ofltm-ServingCellNoResetIDwithinVarLTM-ServingCellNoResetID:

[0551] 3> replace the value ofltm-ServingCellNoResetIDinVarLTM-ServingCellNoResetIDwith the value ofltm-NoResetIDin theLTM-Candidateinltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell;

[0552] 1> if theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell contains the fieldltm-UE-MeasuredTA-ID:

[0553] 2> if the value ofltm-UE-MeasuredTA-IDis not equal to the value ofltm-ServingCellUE-MeasuredTA-IDwithinVarLTM-ServingCellUE-MeasuredTA-ID:

[0554] 3> replace the value ofltm-ServingCellUE-MeasuredTA-IDinVarLTM-ServingCellUE-MeasuredTA-IDwith the value received withinltm-UE-MeasuredTA-ID;

[0555] 3> for eachLTM-CandidateIE inltm-Configorltm-ConfigSCG:

[0556] 4> if the value ofltm-UE-MeasuredTA-IDwithinLTM-CandidateIE is equal to the value ofltm-ServingCellUE-MeasuredTA-IDwithinVarLTM-ServingCellUE-MeasuredTA-ID:

[0557] 5> inform lower layers that the UE is configured with UE-based TA measurements for theLTM-Candidate;

[0558] 4> else:

[0559] 5> inform lower layers that the UE is not configured with UE-based TA measurements for theLTM-Candidate;

[0560] In some implementations, the UE may not be expected to perform UE-based TA measurements for an SpCell.

[0561] 1> else if theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell does not contain the fieldltm-UE-MeasuredTA-ID:

[0562] 2> inform lower layers that the UE is not configured with UE-based TA measurements for theLTM-Candidate.

[0563] 1> ifltm-ConfigCompleteis not included within theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell:

[0564] 2> considerltm-ReferenceConfigurationinltm-Configorltm-ConfigSCG, associated with the cell group for which the LTM cell switch procedure is triggered, to be the current UE configuration for the fields and configurations to be released by the actions above in this procedure;

[0565] 2> ifmeasConfigis included withinltm-ReferenceConfigurationinltm-Configorltm-ConfigSCG;

[0566] 3> perform the measurement configuration procedure by considering themeasConfigwithinltm-ReferenceConfigurationinltm-Configorltm-ConfigSCGas the receivedmeasConfig:

[0567] 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, unless specified otherwise in this procedure.

[0568] 1> if the LTM cell switch is triggered by an indication from lower layers:

[0569] 2> apply theRRCReconfigurationmessage inltm-CandidateConfigwithinLTM-CandidateIE inltm-Configorltm-ConfigSCGidentified by the LTM candidate configuration identity received from lower layers;

[0570] 1> else (LTM cell switch triggered upon cell selection performed while timer T311 was running):

[0571] 2> apply theRRCReconfigurationmessage inltm-CandidateConfigwithinLTM-CandidateIE inltm-Configrelated to the LTM candidate configuration identity for the selected cell;

[0572] 1> release the radio bearer(s) and the logical channel(s) that were part of the UE configuration before of this LTM cell switch procedure but not part of the LTM candidate configuration either indicated by lower layers or for the selected cell, or the LTM reference configuration (in case the LTM candidate configuration does not includeltm-ConfigComplete).

[0573] Whenltm-ConfigCompleteis not included for an LTM candidate configuration, before an LTM cell switch is triggered a UE implementation may generate and store anRRCReconfigurationmessage by applying the received LTM candidate configuration on top of the LTM reference configuration, and the storedRRCReconfigurationmessage is applied when the LTM cell switch is triggered. It is up to the UE to ensure that the RRC reconfiguration applied at the time of LTM cell switch is in accordance with the latest LTM reference configuration and LTM candidate configuration.

[0574] 2. Second example of LTM cell switch execution procedure

[0575] Upon the indication by lower layers that an LTM cell switch procedure is triggered, or upon performing LTM cell switch following cell selection performed while timer T311 was running, or upon the fulfilment of CLTM cell switch conditions, the UE shall:

[0576] 1> if this procedure is triggered due to fulfilment of LTM cell switch conditions:

[0577] 2> if more than one LTM candidate configuration has triggered this procedure:

[0578] 3> select one of the LTM candidate configurations as the selected cell for the LTM cell switch execution;

[0579] 2> stop the LTM conditions evaluation (based on L1 and / or L3 measurements), if any, for all the LTM candidate configurations associated with the cell group for which the LTM cell switch procedure is triggered;

[0580] 2> if theLTM-CandidateIE for the selected LTM candidate configuration includes the fieldcltm-ExecutionConditions(or,ltm-ExecutionConditionList):

[0581] 3> if the fieldl3-Conditionsis included withincltm-ExecutionConditions:

[0582] 4> perform the LTM cell switch conditions evaluation based on L3 measurements according to the receivedcltm-ExecutionConditions;

[0583] 3> else if the fieldl1-Conditionsis included withincltm-ExecutionConditions:

[0584] 4> inform lower layers to initiate the LTM cell switch conditions evaluation based on L1 measurements according to the received fieldcltm-ExecutionConditions.

[0585] 1> if the LTM cell switch is triggered on the MCG; or

[0586] 1> if the LTM cell switch is triggered on the SCG and the UE has anltm-Configassociated with the MCG:

[0587] 2> release / clear all current dedicated and common radio configurations which have neither been received via SRB1 withinmrdc-SecondaryCellGroup, nor via SRB3 except for the following:

[0588] - the radio bearer configuration (configured viaRadioBearerConfig);

[0589] - thelogicalChannelIdentityandlogicalChannelIdentityExtof RLC bearers configured inRLC-BearerConfigand the associated RLC entities, their state variables, buffers, and timers, except for triggering the associated RLC entities to reset the variable RETX_COUNT its initial value;

[0590] - thebh-LogicalChannelIdentityof BH RLC channels configured inBH-RLC-ChannelConfigand the associated RLC entities, their state variables, buffers, and timers, except for triggering the associated RLC entities to reset the variable RETX_COUNT its initial value;

[0591] - the UE variablesVarLTM-ServingCellNoResetIDandVarLTM-ServingCellUE-MeasuredTA-ID;

[0592] - theltm-Configandltm-ConfigSCG(if configured);

[0593] - the MCG C-RNTI;

[0594] - the AS security configurations associated with the master key;

[0595] - the logged measurement configuration;

[0596] 1> if the LTM cell switch is triggered on the SCG:

[0597] 2> release / clear all current dedicated and common radio configurations which have been received either via SRB1 withinmrdc-SecondaryCellGroup, or via SRB3 except for the following:

[0598] - the radio bearer configuration (configured viaRadioBearerConfigIE);

[0599] - thelogicalChannelIdentityandlogicalChannelIdentityExtof RLC bearers configured inRLC-BearerConfigand the associated RLC entities, their state variables, buffers, and timers, except for triggering the associated RLC entities to reset the variable RETX_COUNT its initial value;

[0600] - thebh-LogicalChannelIdentityof BH RLC channels configured inBH-RLC-ChannelConfigand the associated RLC entities, their state variables, buffers, and timers, except for triggering the associated RLC entities to reset the variable RETX_COUNT its initial value;

[0601] - the UE variablesVarLTM-ServingCellNoResetIDandVarLTM-ServingCellUE-MeasuredTA-ID;

[0602] - theltm-Config;

[0603] - the AS security configurations associated with the secondary key;

[0604] 1> for each SRB / DRB in the current UE configuration:

[0605] 2> if the LTM cell switch is triggered on the MCG and the SRB / DRB using the master key; or

[0606] 2> if the LTM cell switch is triggered on the SCG and the SRB / DRB using the secondary key:

[0607] 3> keep the associated PDCP and SDAP entities, their state variables, buffers and timers;

[0608] 3> release all fields related to the SRB / DRB configuration except forsrb-Identityanddrb-Identity;

[0609] 1> apply the default L1 parameter values as specified in corresponding physical layer specifications except for the parameters for which values are provided in SIB1;

[0610] 1> use the default values for timers T310, T311 and constants N310, N311 associated with the cell group for which the LTM cell switch procedure is triggered, where T310, N310, and N311 are for both MCG and SCG, and T311 is only for the MCG;

[0611] 1> apply the default MAC Cell Group configuration for the cell group for which the LTM cell switch procedure is triggered;

[0612] 1> for eachsrb-Identityin the current UE configuration:

[0613] 2> apply the default SRB configuration for the corresponding SRB;

[0614] 1> if the fieldltm-NoSecurityChangeIDis configured for theLTM-CandidateIE and if the UE does not have any value stored ofltm-ServingCellNoSecurityChangeIDwithinVarLTM-ServingCellNoSecurityChangeID; or

[0615] 1> if the value of fieldltm-NoSecurityChangeIDcontained within theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell is not equal to the value ofltm-ServingCellNoSecurityChangeIDwithinVarLTM-ServingCellNoSecurityChangeID:

[0616] 2> if the LTM cell switch is triggered on the MCG, and if the LTM cell switch is triggered i) due to the indication by lower layers that the LTM cell switch procedure is triggered and / or ii) upon cell selection performed while timer T311 was running:

[0617] 3> update the master security key by performing the AS security key update procedure;

[0618] 2> else if the LTM cell switch is triggered on the SCG, and if the LTM cell switch is triggered i) due to the indication by lower layers that the LTM cell switch procedure is triggered and / or ii) upon cell selection performed while timer T311 was running:

[0619] 3> consider the firstsk-Countervalue in theltm-SK-Counterswithin theVarLTM-ServingCellNoSecurityChangeIDas the selectedsk-Countervalue, and perform security key update procedure;

[0620] 3> remove the selectedsk-Countervalue from theltm-SK-Counterswithin theVarLTM-ServingCellNoSecurityChangeID;

[0621] 2> for eachdrb-Identityvalue that is part of the current UE configuration:

[0622] 3> if the PDCP entity of this DRB is not configured withcipheringDisabled:

[0623] 4> configure the PDCP entity with the ciphering algorithm and KUPenckey associated with the master key (KeNB / KgNB) or secondary key (S-KgNB / S-KeNB), as indicated inkeyToUse, i.e. the ciphering configuration shall be applied to all subsequent PDCP PDUs received and sent by the UE;

[0624] 3> if the PDCP entity of this DRB is configured withintegrityProtection:

[0625] 4> configure the PDCP entity with the integrity protection algorithms according tosecurityConfigand apply the KUPintkey associated with the master key (KeNB / KgNB) or the secondary key (S-KgNB) as indicated inkeyToUse;

[0626] 3> if drb-ContinueROHC is included in pdcp-Config:

[0627] 4> indicate to lower layer thatdrb-ContinueROHCis configured;

[0628] 3> if drb-ContinueEHC-DL is included in pdcp-Config:

[0629] 4> indicate to lower layer thatdrb-ContinueEHC-DLis configured;

[0630] 3> if drb-ContinueEHC-UL is included in pdcp-Config:

[0631] 4> indicate to lower layer thatdrb-ContinueEHC-ULis configured;

[0632] 3> if drb-ContinueUDC is included in pdcp-Config:

[0633] 4> indicate to lower layer thatdrb-ContinueUDCis configured;

[0634] 3> re-establish the PDCP entity of this DRB;

[0635] 2> for eachsrb-Identityvalue that is part of the current UE configuration:

[0636] 3> if the UE has selected a newsk-Countervalue due to this LTM cell switch procedure:

[0637] 4> configure the PDCP entity to apply the integrity protection algorithm and KRRCintkey associated with the master key (KeNB / KgNB) or the secondary key (S-KgNB), as indicated inkeyToUse, i.e. the integrity protection configuration 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;

[0638] 4> configure the PDCP entity to apply the ciphering algorithm and KRRCenckey associated with the master key (KeNB / KgNB) or the secondary key (S-KgNB) as indicated inkeyToUse, i.e. the ciphering configuration 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;

[0639] 4> re-establish the PDCP entity of this SRB;

[0640] 3> else:

[0641] 4> trigger the PDCP entity to perform SDU discard;

[0642] 2> if the value of fieldltm-NoSecurityChangeIDcontained within theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell is not equal to the value ofltm-ServingCellNoSecurityChangeIDwithinVarLTM-ServingCellNoSecurityChangeID:

[0643] 3> replace the value ofltm-ServingCellNoSecurityChangeIDinVarLTM-ServingCellNoSecurityChangeIDwith the value ofltm-NoSecurityChangeIDin theLTM-Candidateinltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell;

[0644] 1> if theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell does not contain the fieldltm-NoResetIDand if the UE does not have any value stored ofltm-ServingCellNoResetIDwithinVarLTM-ServingCellNoResetID; or

[0645] 1> if the value of fieldltm-NoResetIDcontained within theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell is not equal to the value ofltm-ServingCellNoResetIDwithinVarLTM-ServingCellNoResetID:

[0646] 2> for eachlogicalChannelIdentityandlogicalChannelIdentityExtthat is part of the current UE configuration for the cell group for which the LTM cell switch procedure is triggered:

[0647] 3> ifservedRadioBeareris set todrb-Identity:

[0648] 4> after the end of this procedure, re-establish the corresponding RLC entity, after applying the LTM configuration inltm-CandidateConfigwithin theLTM-CandidateIE inltm-Configorltm-ConfigSCG;

[0649] 2> for eachbh-LogicalChannelIdentitythat is part of the current UE configuration for the cell group for which the LTM cell switch procedure is triggered:

[0650] 3> after the end of this procedure, re-establish the corresponding RLC entity, after applying the LTM configuration inltm-CandidateConfigwithin the LTM-Candidate IE inltm-Configorltm-ConfigSCG;

[0651] 2> for eachdrb-Identityvalue that is part of the current UE configuration:

[0652] 3> if this DRB is an AM DRB:

[0653] 4> after the end of this procedure, trigger the PDCP entity of this DRB to perform data recovery, after applying the LTM configuration inltm-CandidateConfigwithinLTM-CandidateIE inltm-Configorltm-ConfigSCG;

[0654] 2> if the value of fieldltm-NoResetIDcontained within theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell is not equal to the value ofltm-ServingCellNoResetIDwithinVarLTM-ServingCellNoResetID:

[0655] 3> replace the value ofltm-ServingCellNoResetIDinVarLTM-ServingCellNoResetIDwith the value ofltm-NoResetIDin theLTM-Candidateinltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell;

[0656] 1> if theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell contains the fieldltm-UE-MeasuredTA-ID:

[0657] 2> if the value ofltm-UE-MeasuredTA-IDis not equal to the value ofltm-ServingCellUE-MeasuredTA-IDwithinVarLTM-ServingCellUE-MeasuredTA-ID:

[0658] 3> replace the value ofltm-ServingCellUE-MeasuredTA-IDinVarLTM-ServingCellUE-MeasuredTA-IDwith the value received withinltm-UE-MeasuredTA-ID;

[0659] 3> for eachLTM-CandidateIE inltm-Configorltm-ConfigSCG:

[0660] 4> if the value ofltm-UE-MeasuredTA-IDwithinLTM-CandidateIE is equal to the value ofltm-ServingCellUE-MeasuredTA-IDwithinVarLTM-ServingCellUE-MeasuredTA-ID:

[0661] 5> inform lower layers that the UE is configured with UE-based TA measurements for theLTM-Candidate;

[0662] 4> else:

[0663] 5> inform lower layers that the UE is not configured with UE-based TA measurements for theLTM-Candidate;

[0664] In some implementations, the UE may not be expected to perform UE-based TA measurements for an SpCell.

[0665] 1> else if theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell does not contain the fieldltm-UE-MeasuredTA-ID:

[0666] 2> inform lower layers that the UE is not configured with UE-based TA measurements for theLTM-Candidate.

[0667] 1> ifltm-ConfigCompleteis not included within theLTM-CandidateIE inltm-Configorltm-ConfigSCGindicated by lower layers or for the selected cell:

[0668] 2> considerltm-ReferenceConfigurationinltm-Configorltm-ConfigSCG, associated with the cell group for which the LTM cell switch procedure is triggered, to be the current UE configuration for the fields and configurations to be released by the actions above in this procedure;

[0669] 2> ifmeasConfigis included withinltm-ReferenceConfigurationinltm-Configorltm-ConfigSCG;

[0670] 3> perform the measurement configuration procedure by considering themeasConfigwithinltm-ReferenceConfigurationinltm-Configorltm-ConfigSCGas the receivedmeasConfig:

[0671] 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, unless specified otherwise in this procedure.

[0672] 1> if the LTM cell switch is triggered by an indication from lower layers:

[0673] 2> apply theRRCReconfigurationmessage inltm-CandidateConfigwithinLTM-CandidateIE inltm-Configorltm-ConfigSCGidentified by the LTM candidate configuration identity received from lower layers;

[0674] 1> else (LTM cell switch triggered upon cell selection performed while timer T311 was running):

[0675] 2> apply theRRCReconfigurationmessage inltm-CandidateConfigwithinLTM-CandidateIE inltm-Configrelated to the LTM candidate configuration identity for the selected cell;

[0676] 1> release the radio bearer(s) and the logical channel(s) that were part of the UE configuration before of this LTM cell switch procedure but not part of the LTM candidate configuration either indicated by lower layers or for the selected cell, or the LTM reference configuration (in case the LTM candidate configuration does not includeltm-ConfigComplete).

[0677] Whenltm-ConfigCompleteis not included for an LTM candidate configuration, before an LTM cell switch is triggered a UE implementation may generate and store anRRCReconfigurationmessage by applying the received LTM candidate configuration on top of the LTM reference configuration, and the storedRRCReconfigurationmessage is applied when the LTM cell switch is triggered. It is up to the UE to ensure that the RRC reconfiguration applied at the time of LTM cell switch is in accordance with the latest LTM reference configuration and LTM candidate configuration.

[0678] According to various embodiments, UE may receive a configuration comprising configurations of one or more candidate cells and one or more execution conditions. The UE may receive a cell switch information comprising at least one of a first cell switch identifier associated with a serving cell, a second cell switch identifier associated with a first candidate cell, or a third cell switch identifier associated with a second candidate cell, and so on. The UE may evaluate the one or more the execution conditions. The UE may perform mobility to the candidate second cell if the execution condition toward the second candidate cell is satisfied and the first cell switch identifier is equal to the third cell switch identifier.

[0679] Furthermore, the method in perspective of the communication device / 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.

[0680] More specifically, the communication device / 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.

[0681] The operations comprise: receiving a candidate configuration for cell switch related to a first candidate cell, wherein the candidate configuration comprises: a configuration of the first candidate cell; one or more execution conditions for cell switch to the first candidate cell; and an identifier (ID) related to the first candidate cell; evaluating the one or more execution conditions for cell switch to the first candidate cell; and applying the configuration of the first candidate cell based on: i) at least one of the one or more execution conditions being fulfilled; and ii) the ID related to the first candidate cell being equal to an ID related to a serving cell.

[0682] Furthermore, the method in perspective of the communication device / 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.

[0683] 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 a candidate configuration for cell switch related to a first candidate cell, wherein the candidate configuration comprises: a configuration of the first candidate cell; one or more execution conditions for cell switch to the first candidate cell; and an identifier (ID) related to the first candidate cell; evaluating the one or more execution conditions for cell switch to the first candidate cell; and applying the configuration of the first candidate cell based on: i) at least one of the one or more execution conditions being fulfilled; and ii) the ID related to the first candidate cell being equal to an ID related to a serving cell.

[0684] Furthermore, the method in perspective of the communication device / 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.

[0685] 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 a candidate configuration for cell switch related to a first candidate cell, wherein the candidate configuration comprises: a configuration of the first candidate cell; one or more execution conditions for cell switch to the first candidate cell; and an identifier (ID) related to the first candidate cell; evaluating the one or more execution conditions for cell switch to the first candidate cell; and applying the configuration of the first candidate cell based on: i) at least one of the one or more execution conditions being fulfilled; and ii) the ID related to the first candidate cell being equal to an ID related to a serving cell.

[0686] 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.

[0687] 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.

[0688] The operations comprise: transmitting, to a user equipment (UE), a candidate configuration for cell switch related to a first candidate cell, wherein the candidate configuration comprises: a configuration of the first candidate cell; one or more execution conditions for cell switch to the first candidate cell; and an identifier (ID) related to the first candidate cell, wherein the configuration of the first candidate cell is applied based on: i) at least one of the one or more execution conditions being fulfilled; and ii) the ID related to the first candidate cell being equal to an ID related to a serving cell.

[0689] The present disclosure may have various advantageous effects.

[0690] For example, the network signalling overhead due to reconfiguration of LTM configuration for every inter-CU LTM cell switch execution can be prevented. Further, the UE interruption due to mobility failure incurred by invalid CLTM cell switch execution can be prevented.

[0691] 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.

[0692] 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 a candidate configuration for cell switch related to a first candidate cell,wherein the candidate configuration comprises:a configuration of the first candidate cell;one or more execution conditions for cell switch to the first candidate cell; andan identifier (ID) related to the first candidate cell;evaluating the one or more execution conditions for cell switch to the first candidate cell; andapplying the configuration of the first candidate cell based on:i) at least one of the one or more execution conditions being fulfilled; andii) the ID related to the first candidate cell being equal to an ID related to a serving cell.2.The method of claim 1, wherein the ID related to the first candidate cell and the ID related to the serving cell comprises an ID related to the first candidate cell for determining whether a security change is needed or not upon a cell switch procedure.3.The method of claim 2, further comprising performing the security change based on the ID related to the first candidate cell being not equal to the ID related to the serving cell.4.The method of claim 3, wherein the security change comprises at least one of:performing a radio link control (RLC) re-establishment;performing a packet data convergence protocol (PDCP) re-establishment;updating a master security key;updating a secondary security key;applying a ciphering configuration;applying a integrity protection configuration; orperforming a data recovery.5.The method of claim 2, wherein the cell switch procedure is initiated based on at least one of the one or more execution conditions being fulfilled, andwherein the cell switch procedure comprises applying the configuration of the first candidate cell.6.The method of claim 1, wherein the ID related to the first candidate cell is equal to the ID related to the serving cell based on the first candidate cell and the serving cell being related to a same central unit (CU), andwherein the ID related to the first candidate cell is not equal to the ID related to the serving cell based on the first candidate cell and the serving cell being related to different CUs.7.The method of claim 1, wherein the evaluating of the one or more execution conditions for cell switch to the first candidate cell comprises evaluating the one or more execution conditions for cell switch to the first candidate cell based on the ID related to the first candidate cell being equal to the ID related to the serving cell.8.The method of claim 1, wherein the ID related to the serving cell is received from the serving cell via a cell switch configuration comprising the candidate configuration related to the first candidate cell.9.The method of claim 1, wherein the receiving of the candidate configuration for cell switch related to the first candidate cell comprises receiving a cell switch configuration comprising the candidate configuration related to the first candidate cell and a candidate configuration related to a second candidate cell,wherein the candidate configuration related to the first candidate cell further comprises one or more execution conditions for subsequent cell switch to the second candidate cell, andwherein the candidate configuration related to the second candidate cell comprises:a configuration of the second candidate cell; andan ID related to the second candidate cell.10.The method of claim 9, after applying the configuration of the first candidate cell, further comprising:evaluating the one or more execution conditions for subsequent cell switch to the second candidate cell; andapplying the configuration of the second candidate cell based on:i) at least one of the one or more execution conditions for subsequent cell switch being fulfilled; andii) the ID related to the second candidate cell being equal to the ID related to the first candidate cell.11.The method of claim 9, after applying the configuration of the first candidate cell, further comprising:receiving a cell switch command comprising an ID of the candidate configuration related to the second candidate cell; andapplying the configuration of the second candidate cell, regardless of whether the ID related to the second candidate cell is equal to the ID related to the first candidate cell or not.12.The method of claim 9, after applying the configuration of the first candidate cell, further comprising:selecting a cell based on detecting a failure; andapplying the configuration of the second candidate cell based on the selected cell being the second candidate cell, regardless of whether the ID related to the second candidate cell is equal to the ID related to the first candidate cell or not.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 a candidate configuration for cell switch related to a first candidate cell,wherein the candidate configuration comprises:a configuration of the first candidate cell;one or more execution conditions for cell switch to the first candidate cell; andan identifier (ID) related to the first candidate cell;evaluating the one or more execution conditions for cell switch to the first candidate cell; andapplying the configuration of the first candidate cell based on:i) at least one of the one or more execution conditions being fulfilled; andii) the ID related to the first candidate cell being equal to an ID related to a serving cell.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 a candidate configuration for cell switch related to a first candidate cell,wherein the candidate configuration comprises:a configuration of the first candidate cell;one or more execution conditions for cell switch to the first candidate cell; andan identifier (ID) related to the first candidate cell;evaluating the one or more execution conditions for cell switch to the first candidate cell; andapplying the configuration of the first candidate cell based on:i) at least one of the one or more execution conditions being fulfilled; andii) the ID related to the first candidate cell being equal to an ID related to a serving cell.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 a candidate configuration for cell switch related to a first candidate cell,wherein the candidate configuration comprises:a configuration of the first candidate cell;one or more execution conditions for cell switch to the first candidate cell; andan identifier (ID) related to the first candidate cell;evaluating the one or more execution conditions for cell switch to the first candidate cell; andapplying the configuration of the first candidate cell based on:i) at least one of the one or more execution conditions being fulfilled; andii) the ID related to the first candidate cell being equal to an ID related to a serving cell.17.A method comprising:transmitting, to a user equipment (UE), a candidate configuration for cell switch related to a first candidate cell,wherein the candidate configuration comprises:a configuration of the first candidate cell;one or more execution conditions for cell switch to the first candidate cell; andan identifier (ID) related to the first candidate cell,wherein the configuration of the first candidate cell is applied based on:i) at least one of the one or more execution conditions being fulfilled; andii) the ID related to the first candidate cell being equal to an ID related to a serving cell.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), a candidate configuration for cell switch related to a first candidate cell,wherein the candidate configuration comprises:a configuration of the first candidate cell;one or more execution conditions for cell switch to the first candidate cell; andan identifier (ID) related to the first candidate cell,wherein the configuration of the first candidate cell is applied based on:i) at least one of the one or more execution conditions being fulfilled; andii) the ID related to the first candidate cell being equal to an ID related to a serving cell.

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