Synchronization state management in wireless communications

Abstract

The invention relates to synchronization state management in wireless communications. According to an embodiment of the present disclosure, a method performed by a user equipment (UE) configured to operate in a wireless communication system comprises the steps of: receiving, from a serving cell, a configuration of a non-serving cell for mobility; considering maintaining uplink synchronization for a non-serving cell; and performing mobility to the non-serving cell based on maintaining uplink synchronization for the non-serving cell, in which maintaining uplink synchronization for the non-serving cell is considered when a timer is running, the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal comprising a timing advance value from the non-serving cell; or the timing difference between the serving cell and the non-serving cell is within a time offset.

Description

Technical Field

[0001] This disclosure relates to synchronization state management in wireless communications. Background Technology

[0002] The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a technology that enables high-speed packet communication. Many proposals have been put forward for LTE objectives, including those aimed at reducing user and vendor costs, improving quality of service, and expanding and improving coverage and system capacity. As upper-layer requirements, 3GPP LTE needs to reduce cost per bit, increase service availability, allow flexible use of frequency bands, have a simple architecture, open interfaces, and appropriate power consumption for terminals.

[0003] The International Telecommunication Union (ITU) and 3GPP have begun developing requirements and specifications for New Radio (NR) systems. 3GPP must identify and develop the technical components needed for the successful standardization of the new RAT (Radio Access Technology) to meet both urgent market demands and the longer-term requirements outlined in the ITU Radiocommunication Sector (ITU-R) International Mobile Telecommunications (IMT)-2020 process. Furthermore, NR should be able to utilize any spectrum band, at least up to 100 GHz, that can be used for wireless communication even in the more distant future.

[0004] The goal of NR is a single technology framework that addresses all use cases, requirements, and deployment scenarios, including enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), ultra-reliable and low-latency communications (URLLC), and more. NR should be inherently backward compatible.

[0005] In wireless communication, user equipment (UE) must be synchronized in the downlink and / or uplink to communicate wirelessly with the network. When the downlink and / or uplink become out of sync, various types of failures may occur. Summary of the Invention

[0006] Technical solution

[0007] One aspect of this disclosure is to provide a method and apparatus for synchronization state management in a wireless communication system.

[0008] According to embodiments of this disclosure, a method performed by a user equipment (UE) configured to operate in a wireless communication system includes the steps of: receiving configuration for a non-serving cell for mobility from a serving cell; considering maintaining uplink synchronization for the non-serving cell; and performing mobility to the non-serving cell based on maintaining the uplink synchronization for the non-serving cell, wherein maintaining the uplink synchronization for the non-serving cell is considered when: a timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal including a timing advance value from the non-serving cell; or the timing difference between the serving cell and the non-serving cell is within a time offset.

[0009] According to embodiments of this disclosure, a method performed by a network node associated with a serving cell and configured to operate in a wireless communication system includes the steps of: sending a configuration for a non-serving cell for mobility to a user equipment (UE); and sending a cell handover command to the UE for the non-serving cell, the cell handover command notifying the configuration to be applied to the mobility, wherein maintaining uplink synchronization for the non-serving cell is considered when: a timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal including a timing advance value from the non-serving cell; or the timing difference between the serving cell and the non-serving cell is within a time offset, and wherein the mobility to the non-serving cell is performed by applying the configuration notified by the cell handover command based on maintaining uplink synchronization for the non-serving cell.

[0010] According to various embodiments, an apparatus for implementing the above method is provided.

[0011] This disclosure can have various beneficial effects.

[0012] For example, the UE can manage the UL synchronization state with non-serving cells, thus avoiding mobility failures caused by incorrect UL synchronization state determination for non-serving cells.

[0013] The beneficial effects that can be obtained through specific embodiments of this disclosure are not limited to those listed above. For example, there may be various technical effects that can be understood and / or derived from this disclosure by those skilled in the art. Therefore, the specific effects of this disclosure are not limited to those explicitly described herein, but may include various effects that can be understood or derived from the technical features of this disclosure. Attached Figure Description

[0014] Figure 1An example of a communication system that applies the implementation of this disclosure is shown.

[0015] Figure 2 An example of a wireless device that applies the implementation of this disclosure is shown.

[0016] Figure 3 An example of a UE that applies the implementation of this disclosure is shown.

[0017] Figure 4 and Figure 5 An example of a protocol stack in a 3GPP-based wireless communication system applying the implementation of this disclosure is shown.

[0018] Figure 6 The frame structure in a 3GPP-based wireless communication system applying the implementation of this disclosure is shown.

[0019] Figure 7 An example of a data flow in a 3GPP NR system applying the implementation of this disclosure is shown.

[0020] Figure 8 An example of a dual-connectivity (DC) architecture to which the technical features of this disclosure can be applied is shown.

[0021] Figure 9 An example of a conditional mobility process according to an embodiment of the present disclosure is shown.

[0022] Figure 10 An example of a signaling process for LTM according to an embodiment of this disclosure is shown.

[0023] Figure 11 An example of the timing difference between downlink and uplink frames using an implementation of this disclosure is shown.

[0024] Figure 12 An example of a method performed by a UE according to an embodiment of this disclosure is shown.

[0025] Figure 13 An example of signal flow between a UE and a network node according to an embodiment of this disclosure is shown.

[0026] Figure 14 An example of a method for maintaining TAT-based uplink synchronization for RAR PRACH-less transmissions, according to an embodiment of this disclosure, is shown.

[0027] Figure 15 An example of a method for maintaining uplink synchronization without TAT according to an embodiment of the present disclosure is shown. Detailed Implementation

[0028] The following technologies, devices, and systems can be applied to a variety of wireless multiple access systems. Examples of multiple access systems include Code Division Multiple Access (CDMA) systems, Frequency Division Multiple Access (FDMA) systems, Time Division Multiple Access (TDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single-Carrier Frequency Division Multiple Access (SC-FDMA) systems, and Multi-Carrier Frequency Division Multiple Access (MC-FDMA) systems. CDMA can be implemented using radio technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented using radio technologies such as Global System for Mobile Communications (GSM), Universal Packet Radio Service (GPRS), or Enhanced Data Rate Evolution of GSM (EDGE). OFDMA can be implemented using radio technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). The 3GPP Long Term Evolution (LTE) is part of the Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE uses OFDMA in the downlink (DL) and SC-FDMA in the uplink (UL). The evolution of 3GPP LTE includes LTE-Advanced (LTE-A), LTE-A Pro, and / or 5G New Radio (NR).

[0029] For ease of description, the implementation of this disclosure is primarily described with respect to 3GPP-based wireless communication systems. However, the technical features of this disclosure are not limited thereto. For example, although the following detailed description is based on a mobile communication system corresponding to a 3GPP-based wireless communication system, the aspects of this disclosure, which are not limited to 3GPP-based wireless communication systems, are applicable to other mobile communication systems.

[0030] For any terms and techniques used in this disclosure that are not specifically described, please refer to wireless communication standards documents published prior to this disclosure.

[0031] In this disclosure, "A or B" may mean "A only", "B only", or "both A and B". In other words, in this disclosure, "A or B" can be interpreted as "A and / or B". For example, in this disclosure, "A, B or C" may mean "A only", "B only", "C only", or "any combination of A, B and C".

[0032] In this disclosure, a forward slash ( / ) or a comma (,) can mean "and / or". For example, "A / B" can mean "A and / or B". Therefore, "A / B" can mean "A only", "B only", or "both A and B". For example, "A, B, C" can mean "A, B, or C".

[0033] In this disclosure, "at least one of A and B" may mean "only A", "only B" or "both A and B". Furthermore, the expressions "at least one of A or B" or "at least one of A and / or B" in this disclosure may be interpreted as the same as "at least one of A and B".

[0034] Additionally, in this disclosure, "at least one of A, B, and C" may mean "A only", "B only", "C only" or "any combination of A, B, and C". Furthermore, "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".

[0035] Furthermore, the brackets used in this disclosure may mean "for example". Specifically, when shown as "Control Information (PDCCH)", "PDCCH" can be cited as an example of "Control Information". In other words, "Control Information" in this disclosure is not limited to "PDCCH", and "PDCCH" can be cited as an example of "Control Information". Additionally, even when shown as "Control Information (i.e., PDCCH)", "PDCCH" can be cited as an example of "Control Information".

[0036] The technical features described individually in a single figure in this disclosure can be implemented individually or simultaneously.

[0037] While not limited thereto, the various descriptions, functions, processes, suggestions, methods and / or operation flowcharts disclosed herein can be applied to various fields requiring wireless communication and / or connectivity between devices (e.g., 5G).

[0038] In the following description, the present disclosure will be described in more detail with reference to the accompanying drawings. Unless otherwise stated, the same reference numerals in the following drawings and / or description may refer to the same and / or corresponding hardware blocks, software blocks and / or functional blocks.

[0039] Figure 1 An example of a communication system that applies the implementation of this disclosure is shown.

[0040] Figure 1 The 5G use cases shown are merely illustrative, and the technical features of this disclosure can be applied to... Figure 1 Other 5G use cases not shown.

[0041] The three main demand categories for 5G include: (1) enhanced mobile broadband (eMBB), (2) massive machine-type communications (mMTC), and (3) ultra-reliable and low-latency communications (URLLC).

[0042] Reference Figure 1The communication system 1 includes wireless devices 100a to 100f, a base station (BS) 200, and a network 300. Although Figure 1 An example of a 5G network as a network of communication system 1 is illustrated, but the implementation of this disclosure is not limited to 5G systems and can be applied to future communication systems other than 5G systems.

[0043] BS200 and Network 300 can be implemented as wireless devices, and a particular wireless device can operate as a BS / network node relative to other wireless devices.

[0044] Wireless devices 100a to 100f represent devices that perform communication using radio access technology (RAT) (e.g., 5G NR or LTE) and may be referred to as communication / radio / 5G devices. Wireless devices 100a to 100f may include, but are not limited to, robots 100a, vehicles 100b-1 and 100b-2, extended reality (XR) devices 100c, handheld devices 100d, home appliances 100e, Internet of Things (IoT) devices 100f, and artificial intelligence (AI) devices / servers 400. For example, vehicles may include vehicles with wireless communication capabilities, autonomous vehicles, and vehicles capable of communication between vehicles. Vehicles may include unmanned aerial vehicles (UAVs) (e.g., drones). XR devices may include augmented reality (AR) / virtual reality (VR) / mixed reality (MR) devices and may be implemented in the form of head-mounted displays (HMDs), head-up displays (HUDs) installed in vehicles, televisions, smartphones, computers, wearable devices, home appliances, digital signage, vehicles, robots, etc. Handheld devices may include smartphones, smart tablets, wearable devices (e.g., smartwatches or smart glasses), and computers (e.g., laptops). Home appliances may include TVs, refrigerators, and washing machines. IoT devices may include sensors and smart meters.

[0045] In this disclosure, wireless devices 100a to 100f may be referred to as user equipment (UE). UE may include, for example, cellular phones, smartphones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation systems, tablet PCs, ultrabooks, vehicles, vehicles with autonomous driving capabilities, connected cars, UAVs, AI modules, robots, AR devices, VR devices, MR devices, holographic devices, public safety devices, MTC devices, IoT devices, medical devices, FinTech devices (or financial devices), security devices, weather / environment devices, devices related to 5G services, or devices related to the Fourth Industrial Revolution.

[0046] Wireless devices 100a to 100f can connect to network 300 via BS200. AI technology can be applied to wireless devices 100a to 100f, and wireless devices 100a to 100f can connect to AI server 400 via network 300. Network 300 can be configured using 3G, 4G (e.g., LTE), 5G (e.g., NR), and super 5G networks. While wireless devices 100a to 100f can communicate with each other via BS200 / network 300, wireless devices 100a to 100f can also perform direct communication with each other without going through BS200 / network 300 (e.g., sidelink communication). For example, vehicles 100b-1 and 100b-2 can perform direct communication (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). IoT devices (e.g., sensors) can perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

[0047] Wireless communication / connections 150a, 150b, and 150c can be established between wireless devices 100a to 100f and / or between wireless devices 100a to 100f and BS200 and / or between BS200. These wireless communication / connections can be established via various RATs (e.g., 5G NR) such as uplink / downlink communication 150a, sidelink communication (or device-to-device (D2D) communication) 150b, and inter-base station communication 150c (e.g., relay, integrated access and backhaul (IAB)). Wireless devices 100a to 100f and BS200 / wireless devices 100a to 100f can transmit / receive radio signals to / from each other via wireless communication / connections 150a, 150b, and 150c. For example, wireless communication / connections 150a, 150b, and 150c can transmit / receive signals via various physical channels. Therefore, at least a portion of various configuration information configuration processes, various signal processing processes (e.g., channel coding / decoding, modulation / demodulation, and resource mapping / demapping), and resource allocation processes for transmitting / receiving radio signals can be performed based on various proposals of this disclosure.

[0048] NR supports multiple parameter sets (numerologies) (and / or multiple subcarrier spacings (SCS)) to support a variety of 5G services. For example, if the SCS is 15kHz, wide-area coverage can be supported in traditional cellular bands, while if the SCS is 30kHz / 60kHz, dense urban areas, lower latency, and wider carrier bandwidth can be supported. If the SCS is 60kHz or higher, bandwidths greater than 24.25GHz can be supported to overcome phase noise.

[0049] NR bands can be defined as two types of frequency ranges: frequency range 1 (FR1) and frequency range 2 (FR2). The numerical values ​​of the frequency ranges can vary. For example, the two types (FR1 and FR2) of frequency ranges can be shown in Table 1 below. For ease of explanation, in the frequency ranges used in NR systems, FR1 can represent "the range below 6 GHz," FR2 can represent "the range above 6 GHz," and can be referred to as millimeter wave (mmW).

[0050] [Table 1]

[0051] Frequency range name Corresponding frequency range Subcarrier spacing FR1 450MHz-6000MHz 15, 30, 60kHz FR2 24250MHz-52600MHz 60, 120, 240kHz

[0052] As described above, the frequency range of the NR system can be varied. For example, FR1 can include a frequency band from 410MHz to 7125MHz as shown in Table 2 below. That is, FR1 can include a frequency band of 6GHz (or 5850MHz, 5900MHz, 5925MHz, etc.) or higher. For example, the 6GHz (or 5850MHz, 5900MHz, 5925MHz, etc.) or higher frequency band included in FR1 can include unlicensed frequency bands. Unlicensed frequency bands can be used for various purposes, such as for vehicle communications (e.g., autonomous driving).

[0053] [Table 2]

[0054] Frequency range name Corresponding frequency range Subcarrier spacing FR1 410MHz-7125MHz 15, 30, 60kHz FR2 24250MHz-52600MHz 60, 120, 240kHz

[0055] Here, the radio communication technologies implemented in the wireless devices of this disclosure may include narrowband Internet of Things (NB-IoT) technologies for low-power communication and LTE, NR, and 6G. For example, NB-IoT technology may be an example of low-power wide-area network (LPWAN) technology, implemented in specifications such as LTE Cat NB1 and / or LTE Cat NB2, and may not be limited to the names mentioned above. Additionally and / or alternatively, the radio communication technologies implemented in the wireless devices of this disclosure may communicate based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and may be referred to by various names such as enhanced machine-type communication (eMTC). For example, LTE-M technology may be implemented in at least one of 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 names mentioned above. Additionally and / or alternatively, the radio communication technologies implemented in the wireless devices of this 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 names mentioned above. 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 referred to by various names. Figure 2 An example of a wireless device that applies the implementation of this disclosure is shown.

[0056] exist Figure 2 In this context, the first wireless device 100 and / or the second wireless device 200 can be implemented in various forms depending on the usage / service. For example, {the first wireless device 100 and the second wireless device 200} can correspond to... Figure 1 The first wireless device 100 and / or the second wireless device 200 may be configured from various elements, devices / components and / or modules.

[0057] The first wireless device 100 may include at least one transceiver (e.g., transceiver 106), at least one processing chip (e.g., processing chip 101), and / or one or more antennas 108.

[0058] The processing chip 101 may include at least one processor (e.g., processor 102) and at least one memory (e.g., memory 104). Additionally and / or alternatively, the memory 104 may be located outside the processing chip 101.

[0059] Processor 102 can control memory 104 and / or transceiver 106, and can be adapted to implement the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts described in this disclosure. For example, processor 102 can process information in memory 104 to generate first information / signal, and then transmit a radio signal including the first information / signal via transceiver 106. Processor 102 can receive a radio signal including a second information / signal via transceiver 106, and then store the information obtained by processing the second information / signal in memory 104.

[0060] Memory 104 may be operatively connected to processor 102. Memory 104 may store various types of information and / or instructions. Memory 104 may store firmware and / or software code 105, which implements code, commands, and / or command sets that, when executed by processor 102, execute the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. For example, firmware and / or software code 105 may implement instructions that, when executed by processor 102, execute the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. For example, firmware and / or software code 105 may control processor 102 to execute one or more protocols. For example, firmware and / or software code 105 may control processor 102 to execute one or more layers of wireless interface protocols.

[0061] In this document, processor 102 and memory 104 may be part of a communication modem / circuit / chip designed to implement RAT (e.g., LTE or NR). Transceiver 106 may be connected to processor 102 and transmit and / or receive radio signals via one or more antennas 108. Each transceiver 106 may include a transmitter and / or a receiver. Transceiver 106 may be used interchangeably with a radio frequency (RF) unit. In this disclosure, first wireless device 100 may represent a communication modem / circuit / chip.

[0062] The second wireless device 200 may include at least one transceiver (e.g., transceiver 206), at least one processing chip (e.g., processing chip 201), and / or one or more antennas 208.

[0063] The processing chip 201 may include at least one processor (e.g., processor 202) and at least one memory (e.g., memory 204). Additionally and / or alternatively, the memory 204 may be located outside the processing chip 201.

[0064] Processor 202 can control memory 204 and / or transceiver 206, and can be adapted to implement the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts described in this disclosure. For example, processor 202 can process information in memory 204 to generate third information / signal, and then transmit a radio signal including the third information / signal via transceiver 206. Processor 202 can receive a radio signal including a fourth information / signal via transceiver 106, and then store the information obtained by processing the fourth information / signal in memory 204.

[0065] Memory 204 may be operatively connected to processor 202. Memory 204 may store various types of information and / or instructions. Memory 204 may store firmware and / or software code 205, which implements code, commands, and / or command sets that, when executed by processor 202, execute the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. For example, firmware and / or software code 205 may implement instructions that, when executed by processor 202, execute the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. For example, firmware and / or software code 205 may control processor 202 to execute one or more protocols. For example, firmware and / or software code 205 may control processor 202 to execute one or more layers of wireless interface protocols.

[0066] In this document, processor 202 and memory 204 may be part of a communication modem / circuit / chip designed to implement RAT (e.g., LTE or NR). Transceiver 206 may be connected to processor 202 and transmit and / or receive radio signals via one or more antennas 208. Each of transceivers 206 may include a transmitter and / or a receiver. Transceivers 206 may be used interchangeably with RF units. In this disclosure, second wireless device 200 may represent a communication modem / circuit / chip.

[0067] The hardware elements of wireless devices 100 and 200 will be described in more detail below. One or more protocol layers may be implemented by, but are not limited to, one or more processors 102 and 202. For example, one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as the 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). One or more processors 102 and 202 may generate one or more Protocol Data Units (PDUs), one or more Service Data Units (SDUs), messages, control information, data, or information in accordance with the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. 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, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure, and provide the generated signals to one or more transceivers 106 and 206. One or more processors 102 and 202 may receive signals (e.g., baseband signals) from one or more transceivers 106 and 206 and obtain PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure.

[0068] One or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. 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 one or more processors 102 and 202. For example, one or more processors 102 and 202 may be configured by a set of communication control processors, application processors (APs), electronic control units (ECUs), central processing units (CPUs), graphics processing units (GPUs), and memory control processors.

[0069] One or more memories 104 and 204 can be connected to one or more processors 102 and 202 and store various types of data, signals, messages, information, programs, code, instructions, and / or commands. One or more memories 104 and 204 can be configured with 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 disk drive, registers, cache memory, computer-readable storage media, and / or combinations thereof. One or more memories 104 and 204 can be located internally and / or externally to one or more processors 102 and 202. One or more memories 104 and 204 can be connected to one or more processors 102 and 202 via various technologies such as wired or wireless connections.

[0070] One or more transceivers 106 and 206 can transmit user data, control information, and / or radio signals / channels mentioned in the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure to one or more other devices. One or more transceivers 106 and 206 can receive user data, control information, and / or radio signals / channels mentioned in the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure from one or more other devices. For example, one or more transceivers 106 and 206 can be connected to one or more processors 102 and 202 and transmit and receive radio signals. For example, one or more processors 102 and 202 can perform control to enable one or more transceivers 106 and 206 to transmit user data, control information, or radio signals to one or more other devices. One or more processors 102 and 202 can perform control to enable one or more transceivers 106 and 206 to receive user data, control information, or radio signals from one or more other devices.

[0071] One or more transceivers 106 and 206 may be connected to one or more antennas 108 and 208. Additionally or alternatively, one or more transceivers 106 and 206 may include one or more antennas 108 and 208. 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, processes, suggestions, methods, and / or operation flowcharts disclosed herein via one or more antennas 108 and 208. In this disclosure, one or more antennas 108 and 208 may be multiple physical antennas or multiple logical antennas (e.g., antenna ports).

[0072] One or more transceivers 106 and 206 can convert received user data, control information, radio signals / channels, etc., from RF band signals to baseband signals, so that the received user data, control information, radio signals / channels, etc., can be processed by one or more processors 102 and 202. One or more transceivers 106 and 206 can also convert user data, control information, radio signals / channels, etc., processed by one or more processors 102 and 202 from baseband signals to RF band signals. For this purpose, one or more transceivers 106 and 206 may include (analog) oscillators and / or filters. For example, one or more transceivers 106 and 206, under the control of one or more processors 102 and 202, can up-convert OFDM baseband signals to OFDM signals using their (analog) oscillators and / or filters and transmit the up-converted OFDM signals at the carrier frequency. One or more transceivers 106 and 206 can receive OFDM signals on a carrier frequency and, under the control of one or more processors 102 and 202, downconvert the OFDM signals to OFDM baseband signals via their (analog) oscillators and / or filters.

[0073] although Figure 2 Not shown, but wireless devices 100 and 200 may also include additional components. The additional components 140 may be configured differently depending on the type of wireless devices 100 and 200. For example, the additional components 140 may include at least one of a power unit / battery, input / output (I / O) devices (e.g., audio I / O ports, video I / O ports), drive devices, and computing devices. The additional components 140 may be coupled to one or more processors 102 and 202 via various technologies such as wired or wireless connections.

[0074] In the implementations of this disclosure, the UE can be used as a transmitting device in the uplink (UL) and a receiving device in the downlink (DL). In the implementations of this disclosure, the BS can be used as a receiving device in the UL and a transmitting device in the DL. Hereinafter, for ease of description, it is primarily assumed that the first wireless device 100 is used as the UE and the second wireless device 200 is used as the BS. For example, a processor 102 connected to, installed on, or started in the first wireless device 100 can be adapted to perform UE actions according to the implementations of this disclosure or to control the transceiver 106 to perform UE actions according to the implementations of this disclosure. A processor 202 connected to, installed on, or started in the second wireless device 200 can be adapted to perform BS actions according to the implementations of this disclosure or to control the transceiver 206 to perform BS actions according to the implementations of this disclosure.

[0075] In this disclosure, BS is also referred to as Node B (NB), eNode B (eNB), or gNB.

[0076] Figure 3 An example of a UE that applies the implementation of this disclosure is shown.

[0077] Reference Figure 3 UE 100 can correspond to Figure 2 The first wireless device 100.

[0078] The 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.

[0079] Processor 102 may be adapted to implement the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. Processor 102 may be adapted to control one or more other components of UE 100 to implement the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. A radio interface protocol layer may be implemented in processor 102. Processor 102 may include an ASIC, other chipsets, logic circuits, and / or data processing means. Processor 102 may be an application processor. Processor 102 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator and demodulator). Examples of processor 102 can be found in Qualcomm... SNAPDRAGON manufactured TM Series processors, Samsung EXYNOS manufactured TM Series processors, Apple A series of processors manufactured by MediaTek HELIO manufactured TM Series processors, Intel Manufactured ATOM TM It can be found in the series of processors or the corresponding next-generation processors.

[0080] Memory 104 is coupled to processor 102 during operation and stores various information to operate processor 102. Memory 104 may include ROM, RAM, flash memory, memory card, storage medium, and / or other storage devices. When the implementation is software-based, the techniques described herein can be implemented using modules (e.g., processes, functions, etc.) that perform the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed herein. These modules may be stored in memory 104 and implemented by processor 102. Memory 104 may be implemented within processor 102 or external to processor 102 (in which case, the memory may be communicatively coupled to processor 102 via various means known in the art).

[0081] Transceiver 106 is coupled to processor 102 during operation and transmits and / or receives radio signals. Transceiver 106 includes a transmitter and a receiver. Transceiver 106 may include baseband circuitry for processing radio frequency signals. Transceiver 106 controls one or more antennas 108 to transmit and / or receive radio signals.

[0082] The power management module 141 manages the power of the processor 102 and / or transceiver 106. The battery 142 supplies power to the power management module 141.

[0083] Display 143 outputs the results processed by processor 102. Keypad 144 receives input that will be used by processor 102. Keypad 144 can be displayed on display 143.

[0084] The SIM 145 is an integrated circuit designed to securely store the International Mobile Subscriber Identity (IMSI) number and its associated keys, used to identify and authenticate subscribers on mobile devices such as mobile phones and computers. Contact information can also be stored on many SIM cards.

[0085] Speaker 146 outputs the sound-related results processed by processor 102. Microphone 147 receives the sound-related inputs that will be used by processor 102.

[0086] Figure 4 and Figure 5 An example of a protocol stack in a 3GPP-based wireless communication system applying the implementation of this disclosure is shown.

[0087] Specifically, Figure 4 An example of the user plane protocol stack for the radio interface between the UE and the BS is shown, and Figure 5 An example of the radio interface control plane protocol stack between the UE and the BS is illustrated. The control plane refers to the path for transmitting control messages used for calls managed by the UE and the network. The user plane refers to the path for transmitting data generated in the application layer (e.g., voice data or Internet packet data). See reference... Figure 4 The user plane protocol stack can be divided into Layer 1 (L1, e.g., the PHY layer) and Layer 2 (L2, e.g., the MAC / RLC / PDCP layer). See [reference needed]. Figure 5 The control plane protocol stack can be divided into Layer 1 (L1, e.g., PHY layer), Layer 2 (L2, e.g., MAC / RLC / PDCP layer), Layer 3 (L3, e.g., RRC layer), and the Non-Access Layer (NAS). Layers 1, 2, and 3 are collectively referred to as the Access Layer (AS).

[0088] In 3GPP LTE systems, Layer 2 is separated into the following sublayers: MAC, RLC, and PDCP. In 3GPP NR systems, Layer 2 is separated into the following sublayers: MAC, RLC, PDCP, and SDAP. The PHY layer provides transport channels to the MAC sublayer, the MAC sublayer provides logical channels to the RLC sublayer, the RLC sublayer provides RLC channels to the PDCP sublayer, and the PDCP sublayer provides radio bearers to the SDAP sublayer. The SDAP sublayer provides Quality of Service (QoS) streams to the 5G core network.

[0089] In the 3GPP NR system, the main services and functions of the MAC sublayer include: mapping between logical channels and transport channels; multiplexing MAC SDUs belonging to one or different logical channels to / from the physical layer delivered to / from the transport channel a transport block (TB); demultiplexing from the TB; scheduling information reporting; error correction via Hybrid Automatic Repeat Request (HARQ) (one HARQ entity per cell in the case of carrier aggregation (CA); priority handling between UEs by means of dynamic scheduling; priority handling between logical channels of a UE by means of logical channel priority ordering; and padding. A single MAC entity can support multiple parameter sets, transmission timings, and cells. Mapping constraints in logical channel priority ordering control which parameter set(s), cell(s), and transmission timing(s) a logical channel(s) can use.

[0090] MAC provides different types of data transmission services. To accommodate these different services, various types of logical channels are defined, each supporting the transmission of a specific type of information. Each logical channel type is defined by the type of information being transmitted. Logical channels are divided into two groups: control channels and traffic channels. Control channels are used only for transmitting control plane information, and traffic channels are used only for transmitting user plane information. The Broadcast Control Channel (BCCH) is a downlink logical channel used for broadcasting system control information. The Paging Control Channel (PCCH) is a downlink logical channel that transmits paging information, system information change notifications, and indications of ongoing Public Warning Service (PWS) broadcasts. The Common Control Channel (CCCH) is a logical channel used to send control information between the UE and the network and is used by UEs without an RRC connection to the network. The Dedicated Control Channel (DCCH) is a point-to-point bidirectional logical channel used by UEs with an RRC connection to send dedicated control information between the UE and the network. The Dedicated Traffic Channel (DTCH) is a point-to-point logical channel dedicated to a single UE, used to transmit user information. DTCHs can exist in both the uplink and downlink. In the downlink, the following connections exist between logical channels and transport channels: BCCH can be mapped to the broadcast channel (BCH); BCCH can be mapped to the downlink shared channel (DL-SCH); PCCH can be mapped to the 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 the uplink, the following connections exist between logical channels and transport channels: CCCH can be mapped to the uplink shared channel (UL-SCH); DCCH can be mapped to UL-SCH; and DTCH can be mapped to UL-SCH.

[0091] The RLC sublayer supports three transmission modes: Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM). RLC configuration is per logical channel, independent of parameter sets and / or transmission duration. In 3GPP NR systems, the main services and functions of the RLC sublayer depend on the transmission mode and include: transmission of upper-layer PDUs; sequence numbering independent of either PDCP (UM or AM); error correction via ARQ (AM only); RLC SDU segmentation (AM and UM) and resegmentation (AM only); SDU (AM and UM) reassembly; duplicate detection (AM only); RLC SDU discarding (AM and UM); RLC re-establishment; and protocol error detection (AM only).

[0092] 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); transmission of user data; reordering and deduplication detection; in-order delivery; PDCP PDU routing (in the case of separate bearers); retransmission of PDCP SDUs; encryption, decryption, and integrity protection; PDCP SDU discarding; PDCP re-establishment and data recovery for RLC AM; PDCP status reporting for RLC AM; and PDCPPDU deduplication and deduplication indication for lower layers. The main services and functions of the PDCP sublayer for the control plane include: sequence numbering; encryption, decryption, and integrity protection; transmission of control plane data; reordering and deduplication detection; in-order delivery; and PDCPPDU deduplication and deduplication indication for lower layers.

[0093] In the 3GPP NR system, the main services and functions of SDAP include: mapping between QoS flows and data radio bearers; and marking QoS flow IDs (QFIs) in both DL and UL packets. A single SDAP protocol entity is configured for each individual PDU session.

[0094] In the 3GPP NR system, the main services and functions of the RRC sublayer include: broadcasting system information related to AS and NAS; paging initiated by 5GC or NG-RAN; establishment, maintenance, and release of RRC connections between UE and NG-RAN; security functions including key management; establishment, configuration, maintenance, and release of signaling radio bearers (SRB) and data radio bearers (DRB); mobility functions (including: handover and context delivery; UE cell selection and reselection and control of cell selection and reselection; inter-RAT mobility); QoS management functions; control of UE measurement reports and reports; detection and repair of radio link failures; and NAS message transmission from UE to NAS and from NAS to UE.

[0095] Figure 6 The frame structure in a 3GPP-based wireless communication system applying the implementation of this disclosure is shown.

[0096] Figure 6The frame structure shown is merely exemplary, and the number of subframes, the number of time slots, and / or the number of symbols in a frame can vary. In 3GPP-based wireless communication systems, OFDM parameter sets (e.g., subcarrier spacing (SCS), transmission time interval (TTI) durations) can be configured differently across multiple cells aggregated for a UE. For example, if the UE is configured with different SCSs for cells aggregated for cell aggregation, the (absolute time) duration of time resources (e.g., subframes, time slots, or TTIs) comprising the same number of symbols can be different across the aggregated cells. In this document, symbols can include OFDM symbols (or CP-OFDM symbols), SC-FDMA symbols (or Discrete Fourier Transform-Extended-OFDM (DFT-s-OFDM) symbols).

[0097] Reference Figure 6 Downlink and uplink transmissions are organized into frames. Each frame has a T f = 10ms duration. Each frame is divided into two half-frames, each half-frame having a duration of 5ms. Each half-frame consists of 5 subframes, each subframe having a duration T. sf It is 1ms. Each subframe is divided into time slots, and the number of time slots in a subframe depends on the subcarrier spacing. Each time slot includes 14 or 12 OFDM symbols based on the cyclic prefix (CP). In normal CP, each time slot includes 14 OFDM symbols, and in extended CP, each time slot includes 12 OFDM symbols. The parameter set is based on an exponentially scalable subcarrier spacing βf = 2. u *15kHz.

[0098] Table 3 shows the results based on subcarrier spacing βf = 2. u *Number of OFDM symbols N per slot for normal CP at 15kHz slot symb The number of time slots N in each frame frame，u slot And the number of time slots N in each subframe subframe，u slot .

[0099] [Table 3]

[0100] u <![CDATA[N slot symb ]]> <![CDATA[N frame，u slot ]]> <![CDATA[N subframe，u slot ]]> 0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

[0101] Table 4 shows the results based on subcarrier spacing βf = 2. u *Number of OFDM symbols N per slot for extended CP at 15kHz slot symb The number of time slots N in each frame frame，u slot And the number of time slots N in each subframesubframe，u slot .

[0102] [Table 4]

[0103] u <![CDATA[N slot symb ]]> <![CDATA[N frane，u slot ]]> <![CDATA[N subframe，u slot ]]> 2 12 40 4

[0104] A time slot comprises multiple symbols (e.g., 14 or 12 symbols) in the time domain. For each parameter set (e.g., subcarrier spacing) and carrier, a Common Resource Block (CRB) is defined from the higher-layer signaling (e.g., RRC signaling). start,u grid The beginning of N size,u grid，x *N RB sc Subcarriers and N subframe，u symb A resource grid of OFDM symbols, where N size,u grid,x N represents the number of resource blocks (RBs) in the resource grid, and the subscript x represents the DL for downlink and the UL for uplink. RB sc N is the number of subcarriers per RB. In 3GPP-based wireless communication systems, N... RB sc Typically 12. For a given antenna port p, subcarrier spacing configuration u, and transmission direction (DL or UL), there exists a resource grid. The carrier bandwidth N of the subcarrier spacing configuration u... size,u grid The parameters are given by higher-level parameters (e.g., RRC parameters). Each element in the resource grid for antenna port p and subcarrier spacing configuration u is called a resource element (RE), and a complex symbol can be mapped to each RE. Each RE in the resource grid is uniquely identified by an index k in the frequency domain and an index 1 in the time domain representing the symbol position relative to a reference point. In 3GPP-based wireless communication systems, RBs are defined by 12 consecutive subcarriers in the frequency domain. Figure 6As shown, with the SCS doubling, the slot length and symbol length are halved. For example, when the SCS is 15kHz, the slot length is 1ms, the same as the subframe length. When the SCS is 30kHz, the slot length is 0.5ms (=500us), and the symbol length is half that of the 15kHz SCS. When the SCS is 60kHz, the slot length is 0.25ms (=250us), and the symbol length is half that of the 30kHz SCS. When the SCS is 120kHz, the slot length is 0.125ms (=125us), and the symbol length is half that of the 60kHz SCS. When the SCS is 240kHz, the slot length is 0.0625ms (=62.5us), and the symbol length is half that of the 120kHz SCS.

[0105] In 3GPP NR systems, Resource Blocks (RBs) are classified into CRBs and Physical Resource Blocks (PRBs). For subcarrier spacing configuration u, CRBs are numbered from 0 upwards in the frequency domain. The center of subcarrier 0 of CRB0 used for subcarrier spacing configuration u coincides with "point A," which serves as the common reference point for the resource block grid. In 3GPP NR systems, PRBs are defined within the Bandwidth Part (BWP) and numbered from 0 to N. size BWP,i -1 is the number, where i is the number of bandwidth segments. N physical resource blocks are located within bandwidth segment i. PRB With public resource block N CRB The relationship between N is as follows: PRB =N CRB +N size BWP,i , where N size BWP，i A BWP is a common resource block, where the bandwidth portion begins relative to CRB0. A BWP comprises multiple consecutive RBs. A carrier can include up to N (e.g., 5) BWPs. A UE can be configured with one or more BWPs on a given component carrier. Only one of the multiple BWPs configured for a UE can be active at a time. The active BWP defines the UE's operating bandwidth within the cell's operating bandwidth.

[0106] In this disclosure, the term "cell" can refer to a geographical area in which one or more nodes provide a communication system or to a radio resource. A "cell" as a geographical area can be understood as the coverage area within which a node can provide services using a carrier, and a "cell" as a radio resource (e.g., a time-frequency resource) is associated with bandwidth as a frequency range configured by a carrier. A "cell" associated with a radio resource is defined by a combination of downlink and uplink resources (e.g., a combination of DL component carriers (CC) and ULCC). A cell can be configured by downlink resources only, or it can be configured by both downlink and uplink resources. Since DL coverage (which is the range within which a node can transmit a valid signal) and UL coverage (which is the range within which a node can receive a valid signal from a UE) depend on the carrier carrying the signal, a node's coverage area can be associated with the coverage area of ​​the "cell" of the radio resources used by the node. Therefore, the term "cell" can sometimes be used to refer to the service coverage area of ​​a node, at other times to a radio resource, or at other times to the range within which a signal using a radio resource can reach with effective strength.

[0107] In CA, two or more CCs are aggregated. A UE can receive or transmit on one or more CCs simultaneously, depending on its capabilities. CA is supported for both continuous and non-continuous CCs. When CA is configured, the UE has only one RRC connection with the network. During RRC connection establishment / re-establishment / handover, one serving cell provides NAS mobility information, and during RRC connection re-establishment / handover, one serving cell provides security input. This cell is called the primary cell (PCell). The PCell is the cell operating on the primary frequency, where the UE performs the initial connection establishment procedure or initiates the connection re-establishment procedure. Depending on the UE's capabilities, secondary cells (SCells) can be configured to form a set of serving cells together with the PCell. An SCell is a cell that provides additional radio resources above a special cell (SpCell). Therefore, the set of serving cells configured for a UE always consists of one PCell and one or more SCells. For dual connectivity (DC) operation, the term SpCell refers to the PCell of the primary cell group (MCG) or the primary SCell (PSCell) of the secondary cell group (SCG). SpCell supports PUCCH transmission and contention-based random access and is always active. MCG is a group of serving cells associated with the primary node, comprising SpCell (PCell) and optionally one or more SCells. For a UE with a DC configured, SCG is a subset of serving cells associated with the secondary node, comprising PSCell and zero or more SCells. For a UE in RRC_CONNECTED without a CA / DC configured, only one serving cell consisting of PCells exists. For a UE in RRC_CONNECTED with a CA / DC configured, the term "serving cell" is used to refer to the set of cells consisting of SpCell and all SCells. In the DC, two MAC entities are configured in the UE: one for the MCG and one for the SCG.

[0108] Figure 7 An example of a data flow in a 3GPP NR system applying the implementation of this disclosure is shown.

[0109] Reference Figure 7 "RB" indicates a radio bearer, and "H" indicates a header. Radio bearers are classified into two groups: DRBs for user plane data and SRBs for control plane data. MAC PDUs are sent / received to / from external devices via the PHY layer using radio resources. MAC PDUs arrive at the PHY layer in the form of transport blocks.

[0110] In the PHY layer, the uplink transport channel UL-SCH and random access channel (RACH) are mapped to their respective physical channels, the Physical Uplink Shared Channel (PUSCH) and the Physical Random Access Channel (PRACH), and the downlink transport channels DL-SCH, BCH, and PCH are mapped to the Physical Downlink Shared Channel (PDSCH), the Physical Broadcast Channel (PBCH), and the PDSCH, respectively. In the PHY layer, uplink control information (UCI) is mapped to the Physical Uplink Control Channel (PUCCH), and downlink control information (DCI) is mapped to the Physical Downlink Control Channel (PDCCH). The UE transmits MAC PDUs related to UL-SCH via PUSCH based on UL grant, and the BS transmits MAC PDUs related to DL-SCH via PDSCH based on DL assignment.

[0111] Figure 8 An example of a dual-connectivity (DC) architecture to which the technical features of this disclosure can be applied is shown.

[0112] Reference Figure 8 Examples include MN 811, SN 821, and UE 830, which communicates with both MN 811 and SN 821. Figure 8 As shown, DC refers to a scheme in which a UE (e.g., UE 830) utilizes radio resources provided by at least two RAN nodes, including an MN (e.g., MN 811) and one or more SNs (e.g., SN 821). In other words, DC refers to a scheme in which the UE connects to and communicates with both the MN and one or more SNs. Since the MN and SN may be in different sites, the backhaul between the MN and SN can be interpreted as a non-ideal backhaul (e.g., relatively large delays between nodes).

[0113] MN (e.g., MN 811) refers to the primary RAN node that provides services to the UE in the DC scenario. SN (e.g., SN 821) refers to an additional RAN node that provides services to the UE using MN in the DC scenario. If a RAN node provides services to the UE, then the RAN node can be MN. If MN exists, then SN can also exist.

[0114] For example, an MN can be associated with a macrocell whose coverage area is relatively larger than that of a small cell. However, an MN does not necessarily have to be associated with a macrocell; that is, an MN can be associated with a small cell. Throughout this disclosure, a RAN node associated with a macrocell can be referred to as a "macrocell node." An MN may include a macrocell node.

[0115] For example, a SN can be associated with a small cell (e.g., a microcell, picocell, femtocell) whose coverage area is relatively smaller than that of a macrocell. However, a SN does not necessarily have to be associated with a small cell—that is, a SN can be associated with a macrocell. Throughout this disclosure, a RAN node associated with a small cell can be referred to as a "small cell node." A SN may include a small cell node.

[0116] A Network Node (MN) can be associated with a Primary Cell Group (MCG). An MCG can refer to a group of serving cells associated with an MN and may include a primary cell (PCell) and one or more optional secondary cells (SCells). User plane data and / or control plane data can be transmitted from the core network to the MN via MCG bearers. An MCG bearer refers to a bearer within the MN that hosts radio protocols for using MN resources. Figure 8 As shown, the radio protocols carried by the MCG may include PDCP, RLC, MAC and / or PHY.

[0117] A Service Node (SN) can be associated with a Secondary Cell Group (SCG). An SCG can refer to a group of serving cells associated with the SN and may include primary and secondary cells (PSCells) and one or more optional SCells. User plane data can be transmitted from the core network to the SN via SCG bearers. An SCG bearer refers to a bearer within the SN that hosts radio protocols for using SN resources. Figure 8 As shown, the radio protocols carried by SCG may include PDCP, RLC, MAC, and PHY.

[0118] User plane data and / or control plane data can be transmitted from the core network to the MN and split / copied within the MN, with at least a portion of the split / copied data being forwarded to the SN via a split bearer. A split bearer refers to a radio protocol residing in both the MN and SN to utilize the resources of both. For example... Figure 8 As shown, the radio protocol for a split bearer located in MN may include PDCP, RLC, MAC, and PHY. The radio protocol for a split bearer located in SN may include RLC, MAC, and PHY.

[0119] According to various implementations, a PDCP anchor point / PDCP anchoring point / PDCP anchoring node refers to a RAN node that includes a PDCP entity that splits and / or replicates data and forwards at least a portion of the split / replicated data to another RAN node via the X2 / Xn interface. Figure 8 In the example, the PDCP anchor node can be MN.

[0120] Depending on the implementation method, the MN for the UE can be changed. This can be referred to as a handover or MN switching.

[0121] According to various implementation methods, the SN can start providing radio resources to the UE, establish a connection with the UE, and / or communicate with the UE (i.e., a new SN can be added for the UE). This can be referred to as SN addition.

[0122] According to various implementation methods, the SN for the UE can be changed while maintaining the MN for the UE. This can be referred to as SN change.

[0123] Depending on the implementation, the DC may include E-UTRAN NR-DC (EN-DC) and / or Multiple Radio Access Technology (RAT)-DC (MR-DC). EN-DC refers to a DC in which the UE utilizes radio resources provided by E-UTRAN nodes and NR RAN nodes. MR-DC refers to a DC in which the UE utilizes radio resources provided by RAN nodes with different RATs.

[0124] The following text describes the topic of mobility.

[0125] Mobility can include PCell changes, PSCell changes (or secondary node (SN) changes) and / or PSCell additions (or SN additions).

[0126] There can be at least two types of mobility: network-controlled mobility (or traditional mobility) and UE-based mobility (or conditional mobility).

[0127] Network-controlled mobility (or traditional mobility) involves the network determining the target cell for mobility and configuring the UE with mobility for that target cell. The network can send an RRCReconfiguration message to the UE that includes the configuration for the target cell. Upon receiving the cell configuration for the target cell, the UE can execute mobility for the target cell / apply the configuration for the target cell.

[0128] UE-based mobility (or conditional mobility) refers to the mobility where the network configures the UE with multiple candidate cells and the UE determines the target cell among the candidate cells that meets the mobility execution conditions. Conditional mobility can include at least one of conditional PCell change / conditional handover (CHO) or conditional PSCell mobility. Conditional PSCell mobility can include conditional PSCell addition / change (CPAC), including conditional PSCell addition (CPA) and / or conditional PSCell change (CPC). The network can send an RRCReconfiguration message to the UE including a ConditionalReconfiguration information element (IE), which includes a list of conditional reconfigurations for multiple candidate cells. Conditional reconfiguration for candidate cells can include a conditional reconfiguration identifier, mobility execution conditions for the candidate cell, and configuration for the candidate cell. The UE can evaluate mobility execution conditions for multiple candidate cells, and when the mobility execution conditions for a candidate cell are met, the UE can treat the candidate cell as the target cell and execute the mobility / application configuration for the target cell.

[0129] According to various implementation methods, a mobility execution condition is considered met / satisfied when an entry condition (or entering condition) is met / satisfied at least within the trigger time (TTT) for the mobility execution condition. An entry condition / entering condition may mean that the mobility execution condition is initially met. Once an entry condition is met, the mobility execution condition is considered met if the entry conditions are met consecutively within the duration TTT.

[0130] In this disclosure, the term “switch (HO)” may mean PCell change, or it may be a broad concept that includes not only PCell change but also PSCell change / addition.

[0131] In this disclosure, the terms “handover”, “mobility” and “cell handover” are used interchangeably.

[0132] In this disclosure, the description of switching can also be applied to other mobility processes (e.g., PSCell change / addition).

[0133] Figure 9 An example of a conditional mobility process according to an embodiment of the present disclosure is shown.

[0134] exist Figure 9 middle:

[0135] - The service BS can be associated with a PCell, and the PCell can be the source PCell for the CHO;

[0136] - A service BS can be an MN associated with a SN in a DC, where the SN can be associated with a source PSCell for a CPC; and

[0137] - The target cell can be a target PCcell for CHO or a target PSCell for CPA / CPC.

[0138] Reference Figure 9 In step S901, the UE can receive an RRCReconfiguration message from the serving BS, which includes a Conditional Reconfiguration Information Element (IE) (i.e., Conditional Reconfiguration). The Conditional Reconfiguration IE may include a list of conditional reconfigurations for candidate cells including the target cell. Each conditional reconfiguration in the list may be associated with a corresponding candidate cell and includes i) an identifier for the corresponding conditional reconfiguration (i.e., condReconfigId), ii) one or more execution conditions for the corresponding candidate cell (i.e., condExecutionCond), and / or iii) an RRC reconfiguration for the corresponding candidate cell including cell configuration for the corresponding candidate cell (i.e., condRRCReconfigi). One or more execution conditions may include CHO execution conditions, CPA execution conditions, and / or CPC execution conditions.

[0139] In step S903, the UE can begin evaluating one or more execution conditions for the candidate cell. Figure 9 In this context, it is assumed that the target cell meets the corresponding execution conditions.

[0140] In step S905, the UE can detach from the source PCell / PSCell (in the case of CHO / CPC), apply an RRC reconfiguration for the target cell including the cell configuration for the target cell, and / or synchronize to the target cell. If timing advance (TA) information for the target cell is available, the UE can skip random access toward the target cell—otherwise, the UE should perform random access toward the target cell (e.g., contention-free random access (CFRA) and / or contention-based random access (CBRA)).

[0141] In step S907, the UE can complete the conditional mobility procedure by sending an RRCReconfigurationComplete message to the target cell.

[0142] The following text describes L1 / L2 triggered mobility (LTM).

[0143] LTM is the process by which the gNB receives an L1 measurement report from the UE and, based on that, changes the UE's serving cell via MAC CE. The gNB prepares one or more candidate cells and provides their configurations to the UE via RRC messages. Then, the gNB selects one of the candidate configurations as the target configuration for LTM, triggering an LTM cell handover. Candidate cell configurations can only be added, modified, and released by the network via RRC signaling.

[0144] LTM candidate cells can be configured via an RRCReconfiguration message for the candidate target cell and / or a CellGroupConfig IE for each candidate target cell.

[0145] The following principles can be applied to LTM:

[0146] Candidate cell configurations can be provided as incremental configurations on top of reference configurations. Reference configurations are managed separately, and the UE stores the reference configuration as a separate configuration.

[0147] - Continue the user plane whenever possible (e.g., within a distributed unit, DU) without resetting, where the goal is to avoid additional delays in data loss and data recovery.

[0148] - Security is not updated in LTM.

[0149] - Subsequent LTMs between candidates can be performed without RRC reconfiguration (i.e., the UE does not release other candidate cell configurations after triggering LTM).

[0150] LTM supports intra-gNB-DU and inter-gNB-DU mobility within and between gNB-CUs. LTM also supports inter-frequency mobility, including mobility to cells on frequencies other than the currently serving cell. It can support the following scenarios:

[0151] - PCell changes in non-CA scenarios

[0152] - In the CA scenario, there is no PCell change that modifies the SCell.

[0153] - In a CA scenario, PCell changes that involve SCell changes include the following cases:

[0154] a) The target PCell / target SCell is not the current serving cell (CA-to-CA scenario with PCell change).

[0155] b) The target PCell is the current SCell

[0156] c) The target SCell is the current PCell.

[0157] - Dual connectivity scenarios, at least for PSCell changes without MN involvement (i.e., within SN).

[0158] It also supports inter-cell beam management, but it is not considered a prerequisite for using LTM.

[0159] Designs for L1 / L2-based mobility within and between DUs should share commonalities as much as possible within a reasonable scope.

[0160] In some implementations, upon receiving a candidate cell configuration, a validity / compliance check of the candidate cell configuration is performed.

[0161] Cell handover triggering information is transmitted in a MAC CE that contains at least a candidate configuration index. Cell-specific radio bearer and measurement configurations can be part of the LTM candidate cell configuration.

[0162] In some implementations, the MAC CE can indicate the TCI state (or other beaming information) to be activated for the target cell.

[0163] In some implementations, SCell activation / deactivation can be performed simultaneously with LTM-triggered MAC CE (in the SCell associated with the candidate configuration).

[0164] The UE can perform either contention-based random access (CBRA) or contention-free random access (CFRA) during cell handover. If the UE does not need to acquire timing advance (TA) for the target cell during cell handover, it can also skip the random access procedure. RACH resources for CFRA are provided in the RRC configuration.

[0165] In some implementations, CFRA resources can be provided via MAC CE.

[0166] The entire process for LTM is as follows: Figure 10 As shown in the diagram, subsequent LTMs are completed by repeating the early synchronization, LTM execution, and LTM completion steps without releasing other candidates after each LTM completion.

[0167] Figure 10 An example of a signaling process for LTM according to an embodiment of this disclosure is shown.

[0168] Reference Figure 10 In step S1001, the UE can send a MeasurementReport message to the gNB.

[0169] In step S1003, gNB can decide to use LTM and initiate LTM candidate preparation.

[0170] In step S1005, the gNB may send an RRCReconfiguration message to the UE, which includes the configuration of one or more LTM candidate target cells.

[0171] In step S1007, the UE can store the configuration of the LTM candidate target cell and send an RRCReconfigurationComplete message to the gNB.

[0172] In some implementations, the UE may optionally perform early synchronization (or DL / UL synchronization management) with the candidate cell. In this case, the UE may perform DL synchronization and / or UL synchronization (e.g., TA acquisition) with the candidate target cell before receiving the LTM cell handover command.

[0173] For example, DL synchronization for candidate cells can be performed at least based on SSB support prior to cell handover commands.

[0174] For example, RACH support based at least on PDCCH commands can be used to obtain the TA of a candidate cell before an LTM cell handover command, where the PDCCH command is triggered only by the source cell.

[0175] The UE may perform early synchronization before, after, or during step S1009.

[0176] In step S1009, the UE can perform L1 measurements on the configured LTM candidate target cells and send a lower-layer measurement report to the gNB. The lower-layer measurement report can be carried on L1 or MAC.

[0177] In step S1011, the gNB may decide to perform an LTM cell handover to the target cell.

[0178] In step S1013, the gNB can send a cell handover command MAC CE that triggers LTM cell handover by including the candidate configuration index of the target cell. The UE can then switch to the configuration of the LTM candidate target cell.

[0179] In step S1015, the UE can detach from the source cell and apply the target cell configuration. If the TA is unavailable, the UE can perform a random access procedure (or RACH procedure) toward the target cell.

[0180] In step S1017, the UE can indicate that the LTM cell handover to the target cell has been successfully completed.

[0181] In some implementations, uplink signals or messages after the UE has switched to the target cell can be used to indicate that the LTM cell handover has been successfully completed.

[0182] exist Figure 10 In this context, when the RACH skip condition is met, the RACH process can be skipped (i.e., the UE can perform RACH-free mobility to the target cell). The RACH skip condition may include one or more of the following conditions:

[0183] - The target cell's TA information can be used for the UE and / or the target cell's TA validity;

[0184] - The beam indication of the target cell can be used by the UE and / or when no beam fault is detected on the target cell; or

[0185] - An uplink (UL) license, used to send an uplink signal indicating successful completion of an LTM cell handover, may be available to the UE.

[0186] When performing a random access procedure / RACH procedure: i) if the CFRA resource / dedicated RACH configuration is available to the UE, the UE may perform contention-free random access (CFRA); and ii) if the CFRA resource / dedicated RACH configuration is not available to the UE, the UE may perform contention-based random access (CBRA).

[0187] For CBRA, the UE can send a random access preamble to the RAN node in the uplink. The UE can send Message 1 (MSG1) including the random access preamble to the RAN node. The random access preamble can be associated with a Random Access-Radio Resource Temporary Identifier (RA-RNTI). The random access preamble can be selected based on the selected RACH resource and sent through the time / frequency resource identified by the selected RACH resource.

[0188] For CFRA, the UE can send a dedicated random access preamble to the RAN node in the uplink. The UE can send MSG1, which includes the dedicated random access preamble, to the RAN node. The dedicated random access preamble can be associated with RA-RNTI. The dedicated random access preamble can be selected based on the CFRA resource / dedicated RACH configuration and transmitted through time / frequency resources identified by the CFRA resource / dedicated RACH configuration.

[0189] The following text describes the concept of advance timing (TA).

[0190] Figure 11 An example of the timing difference between downlink and uplink frames using an implementation of this disclosure is shown.

[0191] Reference Figure 11 There is a timing difference (N) between downlink frames and uplink frames. TA -N TA,offset )T c TA can be used to adjust uplink frame timing related to downlink frame timing.

[0192] N TA This refers to the timing advance between the downlink and uplink. It can be based on the Timing Advance Command (TAC) value (or Timing Advance value) T. A Determine N TA .

[0193] In some implementations, the TAC value T A It can be included in the Random Access Response (RAR) or the Absolute TAC MAC CE. In this case, N TA =T A ·16·64 / 2 μ Where μ is for subcarrier spacing 2 μ • Subcarrier spacing configuration of 15 [kHz].

[0194] In some implementations, the TAC value T A It can be included in TAC MAC CE. In this case, N TAnew =N TAold -(T A -31)·16·64 / 2 μ .

[0195] N TA，offset This refers to the fixed offset used to calculate timing advance. N can be determined based on the frequency range and / or frequency band of the cell used for uplink transmission. TA，offset .

[0196] T C It refers to the basic time unit, where T C = 0.509ns.

[0197] Under RRC_CONNECTED, the RAN node can be responsible for maintaining timing advance to keep L1 uplink synchronized. Serving cells with the same timing advance and using the same timing reference cell can be grouped into timing advance groups (TAGs). Each TAG can contain at least one serving cell with a configured uplink, and the mapping from each serving cell to a TAG can be configured by RRC.

[0198] For the primary TAG, the UE can use the PCell as a timing reference, except for shared spectrum channel access. Under certain circumstances, the SCell can also be used as a timing reference. For secondary TAGs, the UE can use any active SCell of that TAG as the timing reference cell, but should not change the timing reference cell unless necessary.

[0199] The RAN node can signal a timing advance update (i.e., TAC value / timing advance value) to the UE via MAC CE commands (e.g., TAC and / or RAR). Such a command can restart a TAG-specific timer (e.g., TimeAlignmentTimer), which indicates whether the L1 uplink is synchronized: the L1 uplink is considered synchronized when the timer is running, otherwise, the L1 uplink is considered asynchronous (in which case uplink transmission can only be performed via MSG1 / MSGA).

[0200] Furthermore, NR Dual Connectivity (NR-DC) is a generalization of NR Intra-NR Dual Connectivity (DC), in which a UE with multiple Rx / Tx capabilities can be configured to utilize resources provided by two different nodes via a non-ideal backhaul connection, both of which provide NR access. One node can act as the primary node (MN), and the other can act as the secondary node (SN). The MN and SN can be connected via a network interface, and at least the MN is connected to the core network.

[0201] To achieve robust SN mobility, Conditional PSCell Change (CPC) is introduced. For CPC, the network can provide the UE with the CPC configuration of candidate serving cells in advance (i.e., pre-configuration of candidate cells for CPC), where the CPC configuration includes a list of RRCReconfiguration messages for candidate cells, associated execution conditions, and / or required conditional measurements. The UE can then begin evaluating the execution conditions. If the execution conditions of a candidate PSCell are met, the UE can perform CPC execution (i.e., apply the RRCReconfiguration message corresponding to the candidate PSCell that meets the execution conditions, and / or send an RRCReconfigurationComplete message to the network). The UE can then synchronize to the PSCell indicated in the RRCReconfiguration message.

[0202] To reduce latency, overhead, and downtime, L1 / L2 triggered mobility (LTM) is introduced. For LTM, the network can provide the UE with the configuration of candidate serving cells in advance (i.e., pre-configuration of candidate cells for LTM). The UE can then perform L1 measurements on the candidate cells and report the L1 measurement results to the network. The network can determine whether the UE should perform LTM on the candidate cells based on the L1 measurement reports. The network can send an LTM cell handover command to the UE via L1 / L2 signaling to trigger the UE to perform LTM towards the candidate cells. Upon receiving the LTM cell handover command, the UE can initiate a cell handover process (i.e., LTM execution on the candidate cells).

[0203] For LTM, the UE can be configured to perform uplink timing management tasks for non-serving cells (i.e., candidate (target) cells and / or neighboring cells). For uplink timing management, the UE can be configured or commanded to perform uplink transmissions to non-serving cells. For example, the UE can be commanded by the network (e.g., a PDCCH command) to send PRACH (i.e., RACH preamble / random access preamble) to non-serving cells.

[0204] In some implementations, the UE can maintain a TimeAlignmentTimer (TAT) to manage uplink synchronization state. Once the UE sends a PRACH for uplink synchronization, it is expected that the UE will receive a response message (RAR) including a TAC associated with a timing value (or TAC value / timing advance value). Upon receiving the TAC value, the UE can initiate or restart the TAT. The UE can adjust the uplink transmission timing based on the received TAC.

[0205] In LTM, a UE can be configured to not receive a RAR including a TAC in response to a PRACH transmission to a non-serving cell. In this case, since the UE does not receive a TAC, it does not initiate or restart the TAT for the non-serving cell. Because the TAT is not restarted, the UE cannot know whether to maintain uplink synchronization with the non-serving cell.

[0206] Therefore, this disclosure provides various implementations for determining the uplink synchronization status of a non-serving cell.

[0207] Figure 12 An example of a method performed by a UE according to an embodiment of the present disclosure is shown. This method can also be performed by a wireless device.

[0208] Reference Figure 12 In step S1201, the UE can receive the configuration for the non-serving cell for mobility from the serving cell.

[0209] In step S1203, the UE may consider maintaining uplink synchronization for a non-serving cell. Maintaining uplink synchronization for a non-serving cell may be considered when: a timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal, including a timing advance value, from the non-serving cell; or the timing difference between the serving cell and the non-serving cell is within the time offset.

[0210] In step S1205, the UE can perform mobility to the non-serving cell based on maintaining uplink synchronization for the non-serving cell.

[0211] According to various implementation methods, the UE can perform uplink synchronization management for the non-serving cell before performing mobility for the non-serving cell. During uplink synchronization management, the UE can consider maintaining uplink synchronization for the non-serving cell.

[0212] According to various implementation methods, while performing uplink synchronization management, the UE can send signals to non-serving cells and start a timer when sending signals to non-serving cells.

[0213] According to various implementation methods, before receiving the second timing advance value from the serving cell, while the timer is running, the UE can apply timing advance for the non-serving cell based on the first timing advance value. Upon receiving the second timing advance value from the serving cell: the UE can start or restart the timer, and while the timer is running, apply timing advance for the non-serving cell based on the second timing advance value. The second timing advance value can be derived from the signal sent to the non-serving cell.

[0214] According to various implementation methods, when performing uplink synchronization management, the UE may: send a signal to a non-serving cell, receive a response to the signal from the non-serving cell, start a timer upon receiving a response including a timing advance value, and apply timing advance for the non-serving cell based on the timing advance value while the timer is running.

[0215] According to various implementations, the signal may include a random access preamble. The response to the signal may include a random access response.

[0216] According to various implementation methods, when performing uplink synchronization management, the UE can:

[0217] Measure the timing difference between the serving cell and the non-serving cell;

[0218] Compare the timing difference between the serving cell and the non-serving cell with the time offset received from the serving cell;

[0219] Based on the timing difference between the serving cell and the non-serving cell within the time offset, the timing advance for the non-serving cell is determined by adding the timing difference between the serving cell and the non-serving cell to the timing advance for the serving cell; and

[0220] When the timing difference between the serving cell and the non-serving cell is within the time offset, the timing advance for the non-serving cell is applied.

[0221] According to various implementation methods, time offsets can be included in the configuration for non-serving cells.

[0222] According to various implementation methods, the UE can send uplink synchronization status information for the non-serving cell to the serving cell based on the fact that uplink synchronization for the non-serving cell has not been maintained. When the timer expires, or when the timing difference between the serving cell and the non-serving cell exceeds the time offset, maintaining uplink synchronization for the non-serving cell can be disregarded.

[0223] According to various implementations, the uplink synchronization status information may include at least one of the following: information for at least one non-serving cell whose timer has expired; information for at least one non-serving cell whose timer is running; information for at least one non-serving cell that has not maintained uplink synchronization; or information for at least one non-serving cell that has maintained uplink synchronization.

[0224] According to various implementation methods, the UE can receive a cell handover command for a non-serving cell from the serving cell via MAC CE signaling. It can also receive configuration for the non-serving cell via Radio Resource Control (RRC) signaling. The UE can perform mobility to the non-serving cell based on the cell handover command. The UE can perform uplink synchronization management for the non-serving cell before receiving the cell handover command.

[0225] According to various implementation methods, mobility may include LTM.

[0226] According to various implementations, the UE can receive uplink signal configuration from the serving cell for uplink synchronization with respect to a non-serving cell. The configuration may include a timer value. The UE can send uplink signals to the non-serving cell based on the uplink signal configuration. The UE can start a timer set to the timer value. If the UE is configured not to receive response messages for uplink signals, the UE can start the timer. While the timer is running, the UE can consider maintaining uplink synchronization with respect to the non-serving cell. When the timer expires, the UE can send a message to the serving cell indicating the non-serving cell.

[0227] According to various implementations, the UE can receive uplink signal configuration for uplink synchronization to a non-serving cell from the serving cell. The configuration may include a timer value. The configuration may indicate whether the UE receives a TAC in response to uplink signal transmission. The UE can transmit uplink signals to the non-serving cell based on the uplink signal configuration. If the UE is configured not to receive a TAC in response to uplink signals, the UE can start a timer set to the timer value when transmitting uplink signals. While the timer is running, the UE can consider maintaining uplink synchronization to the non-serving cell. When the timer expires, the UE can send a message to the serving cell indicating the non-serving cell.

[0228] According to various implementations, the UE can receive information from the serving cell for deriving the Timing Accuracy Allocation (TAC) for uplink synchronization with non-serving cells. The UE can measure the timing difference between the serving cell and the non-serving cell. When the timing difference is within the offset, the UE can consider maintaining uplink synchronization with the non-serving cell. When the timing difference exceeds a threshold, the UE can send a message to the serving cell, wherein the message indicates the non-serving cell.

[0229] Figure 13 An example of signal flow between a UE and a network node according to an embodiment of the present disclosure is shown. The network node may include a base station (BS) and may be associated with a serving cell.

[0230] Reference Figure 13 In step S1301, the network node can send the configuration of the non-serving cell for mobility to the UE.

[0231] In step S1303, the UE may consider maintaining uplink synchronization for a non-serving cell. Maintaining uplink synchronization for a non-serving cell may be considered when: a timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal, including a timing advance value, from the non-serving cell; or the timing difference between the serving cell and the non-serving cell is within the time offset.

[0232] In step S1305, the network node may send a cell handover command to the UE for a non-serving cell, the cell handover command notifying the configuration to be applied to mobility.

[0233] In step S1307, based on maintaining uplink synchronization for non-serving cells, the UE can perform mobility to non-serving cells by applying the configuration notified by the cell handover command.

[0234] According to the implementation of this disclosure, uplink synchronization can be maintained i) based on TAT for RAR PRACH transmission without RAR, or ii) uplink synchronization can be maintained without TAT.

[0235] I. Uplink Synchronization Maintenance / Management Based on TAT for RAR PRACH-less Transmission

[0236] In this implementation, if the UE sends an uplink signal to a non-serving cell for uplink synchronization purposes, the UE can start a timer related to the uplink synchronization with the non-serving cell. While the timer is running, the UE can consider maintaining uplink synchronization with the non-serving cell. When the timer expires, the UE can send a message to the serving cell including the uplink synchronization status related to the non-serving cell. If the timer has not run, the UE can consider the uplink synchronization with the non-serving cell invalid (i.e., out of sync).

[0237] Figure 14 An example of a method for maintaining uplink synchronization for TAT without RAR PRACH transmission, according to an embodiment of the present disclosure, is shown.

[0238] Reference Figure 14 In step S1401, the UE can receive at least one non-serving cell configuration for mobility from the serving cell. The UE can be configured with at least one non-serving cell configuration for mobility. The at least one non-serving cell configuration can be at least one of the following configurations, each associated with a corresponding non-serving cell: radio bearer configuration, measurement configuration, or cell group configuration. That is, the non-serving cell can be a mobility candidate.

[0239] The UE can be configured with uplink transmission resources for non-serving cells. For example, the configuration of uplink transmission resources for non-serving cells can be included in the configuration for non-serving cells received in step S1401. The uplink transmission resources for non-serving cells may include random access (RA) resources for random access to the non-serving cell. RA resources may include PRACH resources.

[0240] The UE can be configured with uplink timing management parameters for non-serving cells. For example, the configuration of uplink timing parameters for non-serving cells can be included in the configuration received for non-serving cells in step S1401. The uplink timing parameters for non-serving cells can include uplink synchronization timer values ​​(e.g., TAT values) associated with the non-serving cell. Where multiple serving cells can share the same uplink synchronization state (e.g., in the case of in-band co-located non-serving cells), multiple serving cells can be grouped such that they are associated with the same uplink synchronization timer.

[0241] The UE can be configured to receive response messages in response to uplink transmissions to a non-serving cell using uplink transmission resources. For example, the configuration for receiving response messages in response to uplink transmissions to a non-serving cell using uplink transmission resources can be included in the configuration for the non-serving cell received in step S1401. For example, the UE can be configured to receive RARs in response to PRACH transmissions.

[0242] In step S1403, the UE can send an uplink signal to the non-serving cell based on uplink transmission resources for the non-serving cell. For example, the transmission of the uplink signal to the non-serving cell can be triggered by a PDCCH from the serving cell. The UE can monitor the PDCCH from the serving cell and send the uplink signal to the non-serving cell based on the indication (or command) from the PDCCH from the serving cell. The uplink signal may include a PRACH preamble.

[0243] In step S1405, the UE can determine whether it is configured to receive a response message in response to uplink signal transmission. For example, this determination can be based on the configuration included in the configuration for the non-serving cell received in step S1401.

[0244] If the UE is configured to receive a response message in response to uplink signal transmission, the UE can monitor the downlink channel (e.g., PDCCH / PDSCH) to receive the response message, and in step S1407, the UE can start a timer set to a TAT value associated with the non-serving cell based on receiving the response message including the TAC value / upon receiving the response message including the TAC value. That is, after the UE sends an uplink signal to the non-serving cell, the non-serving cell can derive the TAC value (or timing advance value) from the uplink signal and send a response message including the TAC value. If the UE receives the response message including the TAC value, the UE can start a timer set to a TAT value associated with the non-serving cell, and / or apply a TA for the non-serving cell based on the TAC value while the timer is running.

[0245] If the UE has been configured not to receive response messages in response to uplink signal transmission, then in step S1409, the UE may start a timer set to a TAT value associated with the non-serving cell when sending uplink signals to the non-serving cell.

[0246] After the UE sends an uplink signal to a non-serving cell, the non-serving cell can derive the TAC value (or timing advance value) from the uplink signal. The non-serving cell can transmit the TAC value to the serving cell, and the serving cell can send the TAC value to the UE (i.e., the UE can receive the TAC value from the serving cell). For example, as... Figure 10 As shown, the TAC value can be included in the cell handover command.

[0247] Before receiving a TAC value from the serving cell, while the timer is running, the UE can apply a TA for a non-serving cell based on another TAC value (e.g., a first TAC value / a (pre)configured default TAC value). After receiving a TAC value from the serving cell, the UE can restart the timer and / or apply a TA for the non-serving cell based on the received TAC value (e.g., a second TAC value) while the timer is running.

[0248] In step S1411, while the timer is running, the UE may consider maintaining uplink synchronization with the non-serving cell.

[0249] In step S1413, upon the expiration of the timer, the UE may send a message to the serving cell to indicate the uplink synchronization status (i.e., uplink synchronization status information) for the non-serving cell. If the timer expires, the UE may consider not maintaining uplink synchronization with the non-serving cell, and the UE may send a message to the serving cell to indicate the uplink synchronization status with the configured non-serving cell. This message may indicate a non-serving cell whose associated TAT has just expired. This message may indicate a non-serving cell that has not maintained uplink synchronization. This message may indicate a non-serving cell that is still maintaining uplink synchronization. This message may indicate a non-serving cell whose associated TAT is currently running.

[0250] In some implementations, it is possible to Figure 10 Executed during the DL / UL synchronization management process Figure 14 At least one of the steps in the process.

[0251] II. Uplink synchronization maintenance / management without TAT

[0252] In this implementation, the UE can measure the DL timing difference (or time alignment error) between the serving cell and the non-serving cell, and deduce the timing advance of the non-serving cell based on this timing difference and / or other parameters received from the serving cell. The UE can then determine whether to maintain uplink synchronization with the non-serving cell based on the measured DL timing difference. If the UE determines that uplink synchronization with the non-serving cell should not be maintained, the UE can send a message to the serving cell including the uplink synchronization status related to the non-serving cell.

[0253] Figure 15 An example of a method for maintaining uplink synchronization without TAT according to an embodiment of the present disclosure is shown.

[0254] Reference Figure 15 In step S1501, the UE may receive parameters for evaluating the uplink synchronization status for the non-serving cell and / or deriving the uplink transmission timing to the non-serving cell. For example, the parameters may include a DL timing offset threshold and / or a TA offset to the non-serving cell. These parameters may be included in the configuration for the non-serving cell.

[0255] In step S1503, the UE can measure the DL timing difference between the serving cell and the non-serving cell.

[0256] In step S1505, the UE can determine whether the DL timing difference between the serving cell and the non-serving cell is within or exceeds the DL timing offset threshold.

[0257] If the UE detects that the DL timing difference between the serving cell and the non-serving cell is within the DL timing offset threshold, then in step S1507, the UE can derive the uplink transmission timing and / or consider maintaining uplink synchronization with the non-serving cell. To derive the uplink transmission timing to the non-serving cell (or the TA for the non-serving cell), the UE can use the TA offset and / or the measured DL timing difference. For example, the UE can determine the uplink transmission timing to the non-serving cell by adding the measured DL timing difference to the timing advance for the serving cell.

[0258] If the UE detects that the DL timing difference between the serving cell and the non-serving cell exceeds the DL timing offset threshold, the UE may consider not maintaining uplink synchronization with the non-serving cell, and / or deducing that the uplink transmission timing to the non-serving cell is invalid. Upon detecting that the DL timing difference between the serving cell and the non-serving cell exceeds the DL timing offset threshold, in step S1509, the UE may send a message to the serving cell to indicate the uplink synchronization status with the configured non-serving cell (i.e., uplink synchronization status information). This message may indicate a non-serving cell whose associated TAT has just expired. This message may indicate a non-serving cell that has not maintained uplink synchronization. This message may indicate a non-serving cell that is still maintaining uplink synchronization. This message may indicate a non-serving cell whose associated TAT is currently running.

[0259] In some implementations, it is possible to Figure 10 Executed during the DL / UL synchronization management process Figure 15 At least one of the steps in the process.

[0260] The above implementation focuses on the uplink synchronization state of non-serving cells, but without loss of generality, the above content can be applied to the uplink synchronization state of serving cells and / or auxiliary serving cells (e.g., inter-cell and / or multi-transmit / receive point (mTRP) cells).

[0261] Furthermore, in this disclosure (for example, Figure 12 The method described from the UE's perspective (in Chinese) can be derived from... Figure 2 The first wireless device 100 and / or shown Figure 3 The UE 100 shown is used to execute this.

[0262] More specifically, the UE includes at least one transceiver, at least one processor, and at least one computer memory operatively connectable to the at least one processor and storing instructions that perform operations based on execution by the at least one processor.

[0263] The operation includes: receiving configuration for the non-serving cell regarding mobility from the serving cell; considering maintaining uplink synchronization for the non-serving cell; and performing mobility to the non-serving cell based on maintaining uplink synchronization for the non-serving cell. Maintaining uplink synchronization for the non-serving cell can be considered when: a timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to that signal, including a timing advance value, from the non-serving cell; or the timing difference between the serving cell and the non-serving cell is within the time offset.

[0264] Furthermore, in this disclosure (for example, in Figure 12 The method described from the UE's perspective (in Chinese) can be stored in... Figure 2 The software code 105 in the memory 104 included in the first wireless device 100 shown is executed.

[0265] More specifically, at least one computer-readable medium (CRM) stores instructions that perform operations based on execution by at least one processor, the operations including: receiving configuration for a non-serving cell for mobility from the serving cell; considering maintaining uplink synchronization for the non-serving cell; and performing mobility to the non-serving cell based on maintaining uplink synchronization for the non-serving cell. Maintaining uplink synchronization for the non-serving cell can be considered when: a timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal, including a timing advance value, from the non-serving cell; or the timing difference between the serving cell and the non-serving cell is within a time offset.

[0266] Furthermore, in this disclosure (for example, in Figure 12 The method described from the UE's perspective (in Chinese) can be... Figure 2The processor 102 included in the first wireless device 100 shown controls and / or transmits data through... Figure 3 The processor 102 included in the UE 100 shown is used for execution.

[0267] More specifically, a device (e.g., a wireless device / UE) configured / suited for operation in a wireless communication system includes at least one processor and at least one computer memory operatively connectable to the at least one processor. The at least one processor is configured / suited to perform operations including: receiving configuration for a non-serving cell regarding mobility from a serving cell; considering uplink synchronization for the non-serving cell; and performing mobility to the non-serving cell based on maintaining uplink synchronization for the non-serving cell. Maintaining uplink synchronization for the non-serving cell can be considered when: a timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal, including a timing advance value, from the non-serving cell; or the timing difference between the serving cell and the non-serving cell is within a time offset.

[0268] Furthermore, in this disclosure (for example, Figure 13 The method described from the perspective of network nodes (in Chinese) can be derived from... Figure 2 The second wireless device 200 shown in the diagram performs this function. The network node can be associated with the serving cell.

[0269] More specifically, the network node includes at least one transceiver, at least one processor, and at least one computer memory operatively connectable to the at least one processor and storing instructions that perform operations based on execution by the at least one processor.

[0270] The operation includes: sending a configuration for the non-serving cell for mobility to the user equipment (UE); and sending a cell handover command for the non-serving cell to the UE, the cell handover command notifying that the configuration is to be applied to mobility. Uplink synchronization for the non-serving cell is considered when: a timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal, including a timing advance value, from the non-serving cell; or the timing difference between the serving cell and the non-serving cell is within the time offset. Based on maintaining uplink synchronization for the non-serving cell, mobility to the non-serving cell can be performed by applying the configuration notified by the cell handover command.

[0271] This disclosure can have various beneficial effects.

[0272] For example, the UE can manage the UL synchronization state with non-serving cells, thus avoiding mobility failures caused by incorrect UL synchronization state determination for non-serving cells.

[0273] The beneficial effects that can be obtained through specific embodiments of this disclosure are not limited to those listed above. For example, there may be various technical effects that can be understood and / or derived from this disclosure by those skilled in the art. Therefore, the specific effects of this disclosure are not limited to those explicitly described herein, but may include various effects that can be understood or derived from the technical features of this disclosure.

[0274] The claims in this disclosure can be combined in various ways. For example, the technical features in the method claims of this disclosure can be combined to implement or perform in a device, and the technical features in the device claims can be combined to implement or perform in a method. Furthermore, the technical features in the method claims and device claims can be combined to implement or perform in a device. Other implementations are within the scope of the appended claims.

Claims

1. A method performed by a user equipment (UE) configured to operate in a wireless communication system, the method comprising the following steps: Receive configuration from the serving cell for mobility-specific non-serving cells; Consider maintaining uplink synchronization for the aforementioned non-serving cells; as well as Based on maintaining uplink synchronization for the non-serving cell, the mobility to the non-serving cell is performed. Specifically, uplink synchronization is considered to be maintained for the non-serving cell in the following situations: The timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal, including a timing advance value, from the non-serving cell; or The timing difference between the serving cell and the non-serving cell is within the time offset.

2. The method according to claim 1, further comprising the following steps: Before implementing mobility to the non-serving cell, uplink synchronization management is performed for the non-serving cell. The steps for performing the uplink synchronization management include: considering maintaining the uplink synchronization for the non-serving cell.

3. The method according to claim 2, wherein, The steps for performing uplink synchronization management for the non-serving cell include: Send the signal to the non-serving cell; and The timer is started when the signal is sent to the non-serving cell.

4. The method according to claim 3, further comprising the following step: Before receiving the second timing advance value from the serving cell, while the timer is running, timing advance is applied for the non-serving cell based on the first timing advance value; as well as Upon receiving the second timing advance value from the serving cell: Start or restart the timer; as well as While the timer is running, a timing advance is applied for the non-serving cell based on the second timing advance value. The second timing advance value is derived from the signal sent to the non-serving cell.

5. The method according to claim 2, wherein, The steps for performing uplink synchronization management for the non-serving cell include: Send the signal to the non-serving cell; Receive the response to the signal from the non-serving cell; The timer is started upon receiving the response including the timing advance value; and While the timer is running, a timing advance is applied for the non-serving cell based on the timing advance value.

6. The method according to claim 1, wherein, The signal includes a random access preamble, and The response to the signal includes a random access response.

7. The method according to claim 2, wherein, The uplink synchronization management performed for the non-serving cell includes: Measure the timing difference between the serving cell and the non-serving cell; The timing difference between the serving cell and the non-serving cell is compared with the time offset received from the serving cell; Based on the timing difference between the serving cell and the non-serving cell within the time offset, the timing advance for the non-serving cell is determined by adding the timing difference between the serving cell and the non-serving cell to the timing advance for the serving cell; and When the timing difference between the serving cell and the non-serving cell is within the time offset, the timing advance for the non-serving cell is applied.

8. The method according to claim 7, wherein, The time offset is included in the configuration for the non-serving cell.

9. The method according to claim 1, further comprising the following steps: Based on the failure to maintain uplink synchronization for the non-serving cell, uplink synchronization status information for the non-serving cell is sent to the serving cell, and Specifically, when the timer expires, or when the timing difference between the serving cell and the non-serving cell exceeds the time offset, maintaining uplink synchronization for the non-serving cell is not considered.

10. The method according to claim 9, wherein, The uplink synchronization status information includes at least one of the following: Information regarding at least one non-serving cell whose timer has expired; Information regarding at least one non-serving cell for which the timer is currently running; Information regarding at least one non-serving cell that has not maintained uplink synchronization; or Information regarding at least one non-serving cell that maintains uplink synchronization.

11. The method according to claim 2, further comprising the following step: Receive a cell handover command for the non-serving cell from the serving cell. The step of executing the mobility to the non-serving cell includes: executing the mobility to the non-serving cell based on the cell handover command for the non-serving cell, and The step of performing uplink synchronization management for the non-serving cell includes: performing uplink synchronization management for the non-serving cell before receiving the cell handover command.

12. The method according to claim 1, wherein, The mobility includes mobility LTMs triggered by layer 1L1 / layer 2L2.

13. The method according to claim 1, wherein, The UE communicates with at least one of a mobile device, a network, or an autonomous vehicle.

14. A user equipment (UE) configured to operate in a wireless communication system, the UE comprising: At least one transceiver; At least one processor; as well as At least one memory, operatively coupled to the at least one processor and storing instructions that perform operations based on execution by the at least one processor, the operations including: Receive configuration from the serving cell for mobility-specific non-serving cells; Consider maintaining uplink synchronization for the aforementioned non-serving cells; and Based on maintaining uplink synchronization for the non-serving cell, the mobility to the non-serving cell is performed. Specifically, uplink synchronization is considered to be maintained for the non-serving cell in the following situations: The timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal, including a timing advance value, from the non-serving cell; or The timing difference between the serving cell and the non-serving cell is within the time offset.

15. The UE according to claim 14, wherein, The UE is configured to implement the method according to any one of claims 2 to 13.

16. A network node associated with a serving cell and configured to operate in a wireless communication system, the network node comprising: At least one transceiver; At least one processor; as well as At least one memory, operatively coupled to the at least one processor and storing instructions that perform operations based on execution by the at least one processor, the operations including: Send the configuration of the non-serving cell for mobility to the user equipment (UE); and A cell handover command for the non-serving cell is sent to the UE, the cell handover command informing the UE that the configuration should be applied to the mobility. Specifically, uplink synchronization for the non-serving cell is considered to be maintained in the following situations: The timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal, including a timing advance value, from the non-serving cell; or The timing difference between the serving cell and the non-serving cell is within the time offset, and Specifically, based on maintaining uplink synchronization for the non-serving cell, mobility to the non-serving cell is performed by applying the configuration notified by the cell handover command.

17. A method performed by a network node associated with a serving cell and configured to operate in a wireless communication system, the method comprising the steps of: Send the configuration of the non-serving cell for mobility to the user equipment (UE); as well as A cell handover command for the non-serving cell is sent to the UE, the cell handover command informing the UE that the configuration should be applied to the mobility. Specifically, uplink synchronization for the non-serving cell is considered to be maintained in the following situations: The timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal, including a timing advance value, from the non-serving cell; or The timing difference between the serving cell and the non-serving cell is within the time offset, and Specifically, based on maintaining uplink synchronization for the non-serving cell, mobility to the non-serving cell is performed by applying the configuration notified by the cell handover command.

18. The method according to claim 17, wherein, The UE is configured to implement the method according to any one of claims 1 to 13.

19. An apparatus suitable for operation in a wireless communication system, the apparatus comprising: At least one processor; as well as At least one memory, operatively coupled to the at least one processor and storing instructions that perform operations based on execution by the at least one processor, the operations including: Receive configuration from the serving cell for mobility-specific non-serving cells; Consider maintaining uplink synchronization for the aforementioned non-serving cells; and Based on maintaining uplink synchronization for the non-serving cell, the mobility to the non-serving cell is performed. Specifically, uplink synchronization is considered to be maintained for the non-serving cell in the following situations: The timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal, including a timing advance value, from the non-serving cell; or The timing difference between the serving cell and the non-serving cell is within the time offset.

20. A non-transitory computer-readable medium (CRM) storing program code implementing instructions that perform operations based on execution by at least one processor, the operations including: Receive configuration from the serving cell for mobility-specific non-serving cells; Consider maintaining uplink synchronization for the aforementioned non-serving cells; as well as Based on maintaining uplink synchronization for the non-serving cell, the mobility to the non-serving cell is performed. Specifically, uplink synchronization is considered to be maintained for the non-serving cell in the following situations: The timer is running, wherein the timer is started when the UE sends a signal to the non-serving cell or receives a response to the signal, including a timing advance value, from the non-serving cell; or The timing difference between the serving cell and the non-serving cell is within the time offset.

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