Apparatus and method for recovering synchronization in wireless communication system

Abstract

The present disclosure relates to a 5th-Generation (5G) or pre-5G communication system to be provided for supporting higher data rates beyond a 4th-Generation (4G) communication system (e.g., Long Term Evolution (LTE)). According to various embodiments of the present disclosure, an apparatus of a terminal in a wireless communication system is provided. The apparatus includes at least one transceiver and at least one processor configured to be operably connected to the at least one transceiver. Wherein the at least one processor may be configured to obtain a first synchronization of a first carrier in synchronization, determine a second synchronization of a second carrier that is not synchronized based on the first synchronization, and perform communication based on the second synchronization.

Description

[0001] This application is a divisional application of a patent application with an application date of March 7, 2019, application number 201980012855.7, and titled “Device and method for restoring synchronization in a wireless communication system”. Technical Field

[0002] The present disclosure relates to a wireless communication system, and more particularly to an apparatus and method for restoring synchronization in a wireless communication system. Background Art

[0003] In order to meet the increased demand for wireless data traffic since the deployment of the fourth generation (4G) communication system, efforts have been made to develop improved fifth generation (5G) or pre-5G communication systems. Therefore, 5G or pre-5G communication systems are also called "beyond 4G networks" or "post-long term evolution (LTE) systems".

[0004] 5G communication systems are considered to be implemented in higher frequency (millimeter wave (mmWave)) bands (e.g., 28 GHz or 60 GHz bands) to achieve higher data rates. In order to reduce the propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple-input multiple-output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna technologies are discussed in 5G communication systems.

[0005] In addition, in the 5G communication system, system network improvements are being developed based on advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, collaborative communications, coordinated multi-point (CoMP), and receiving-end interference cancellation.

[0006] In 5G systems, hybrid frequency shift keying (FSK) and quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC) have been developed as advanced coded modulation (ACM), and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced access technologies.

[0007] In order to receive signals on resources in a wireless communication system, a terminal needs to acquire synchronization. If the terminal fails to successfully acquire synchronization, it may be difficult for the terminal to successfully receive signals.

[0008] The above information is presented as background information only to assist in understanding the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above content may be used as prior art with respect to the present disclosure. Summary of the invention

[0009] Solution to the problem

[0010] Aspects of the present disclosure will address at least the above-mentioned problems and / or disadvantages and provide at least the advantages described below. Therefore, one aspect of the present disclosure provides an apparatus and method for successful synchronization in a wireless communication system.

[0011] Another aspect of the present disclosure is to provide an apparatus and method for recovering synchronization when synchronization fails in a wireless communication system.

[0012] Another aspect of the present disclosure is to provide an apparatus and method for recovering synchronization of an out-of-synchronization component carrier (CC) using a synchronized CC in carrier aggregation (CA) of a wireless communication system.

[0013] Another aspect of the present disclosure is to provide an apparatus and method for recovering synchronization without experiencing a radio link failure (RLF) or a radio reestablishment (RRE) in a wireless communication system.

[0014] Another aspect of the present disclosure is to provide an apparatus and method for recovering synchronization through inter-frequency measurement.

[0015] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments.

[0016] According to one aspect of the present disclosure, a device of a terminal in a wireless communication system is provided. The device includes: at least one transceiver; and at least one processor, the at least one processor is configured to be operably connected to the at least one transceiver, wherein the at least one processor can be further configured to: obtain a first synchronization of a first carrier in synchronization, determine a second synchronization of a second carrier that is not synchronized based on the first synchronization, and perform communication based on the second synchronization.

[0017] According to one aspect of the present disclosure, a method for operating a terminal in a wireless communication system is provided, the method comprising: obtaining a first synchronization of a first carrier in synchronization; determining a second synchronization of an unsynchronized second carrier based on the first synchronization; and performing communication based on the second synchronization.

[0018] The apparatus and method according to various embodiments of the present disclosure can quickly restore synchronization, thereby effectively performing wireless communication.

[0019] Effects obtainable by the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

[0020] Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0022] Figure 1 A wireless communication system according to an embodiment of the present disclosure is shown;

[0023] Figure 2 The configuration of a base station in a wireless communication system according to an embodiment of the present disclosure is shown;

[0024] Figure 3 The configuration of a terminal in a wireless communication system according to an embodiment of the present disclosure is shown;

[0025] Figure 4A The configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure is shown;

[0026] Figure 4B The configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure is shown;

[0027] Figure 4C The configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure is shown;

[0028] Figure 5 An example of synchronization compensation according to an embodiment of the present disclosure is shown;

[0029] Figure 6 A flow chart of a terminal for synchronous compensation according to an embodiment of the present invention is shown;

[0030] Figure 7 A flow chart of a terminal determining synchronization success or failure in carrier aggregation (CA) according to an embodiment of the present invention is shown;

[0031] Fig. 8A A flow chart of a terminal for determining whether synchronization of each carrier is successful or failed according to an embodiment of the present invention is shown;

[0032] Figure 8B A flow chart of a terminal for early synchronization compensation according to an embodiment of the present invention is shown;

[0033] Fig. 9 A flow chart of a terminal for synchronous compensation according to an embodiment of the present invention is shown;

[0034] Fig.10An example of a timer of a terminal for synchronization compensation according to an embodiment of the present disclosure is shown;

[0035] Fig.11A An example of synchronization compensation based on cell deployment according to an embodiment of the present disclosure is shown;

[0036] Fig. 11B An example of synchronization compensation based on an RF path according to an embodiment of the present disclosure is shown;

[0037] Fig.12 A flowchart showing a terminal determining whether CA synchronization is successful or failed according to an embodiment of the present disclosure; and

[0038] Fig.13 A flowchart of a terminal for signal processing according to CA synchronization success or failure according to an embodiment of the present disclosure is shown.

[0039] Throughout the drawings, like reference numerals will be understood to refer to like parts, components, and structures. DETAILED DESCRIPTION

[0040] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of the various embodiments of the present disclosure as defined by the claims and their equivalents. The description includes various specific details that are helpful for understanding, but these are merely exemplary. Therefore, it will be appreciated by those of ordinary skill in the art that various changes and modifications may be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and configurations may be omitted for clarity and brevity.

[0041] The terms and words used in the following specification and claims are not limited to the bibliographical meanings, but are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Therefore, it will be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustrative purposes only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

[0042] It should be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

[0043] Hereinafter, various embodiments of the present disclosure will be described based on a hardware method. However, various embodiments of the present disclosure include techniques using both hardware and software, and therefore, various embodiments of the present disclosure may not exclude the viewpoint of software.

[0044] Hereinafter, the present disclosure relates to an apparatus and method for recovering synchronization in a wireless communication system. Specifically, the present disclosure describes a technology for recovering synchronization of an out-of-sync cell based on synchronization of a cell in synchronization in a wireless communication system.

[0045] The terms used hereinafter regarding frequency {e.g., "carrier", "cell", "frequency band", "carrier frequency", "frequency band", "component carrier (CC)", etc.}, terms regarding network entities, terms regarding components of a device, etc. are illustrative words for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used.

[0046] In addition, the present disclosure will use the terms used in some communication standards {eg, the 3rd Generation Partnership Project (3GPP)} to describe various embodiments, but this is only an illustrative example. The various embodiments of the present disclosure can also be easily modified and can also be applied to other communication systems.

[0047] Figure 1 A wireless communication system according to an embodiment of the present disclosure is shown.

[0048] Reference Figure 1 A base station 110, a terminal 120, and a terminal 130 are shown as a part of nodes using a wireless channel in a wireless communication system.

[0049] The base station 110 is a network infrastructure element that provides wireless access to the terminal 120 and the terminal 130. The base station 110 has a coverage range defined as a specific geographical area based on the distance over which a signal can be transmitted. The base station 110 may be referred to as an "access point (AP)", "eNodeB (eNB)", "fifth generation (5G) node", "radio point" or other terms with equivalent technical meanings, as well as a base station. According to various embodiments, the base station 110 may be connected to one or more "transmit / receive points (TRPs)". The base station 110 may send a downlink signal to the terminal 120 or the terminal 130 or receive an uplink signal from the terminal 120 or the terminal 130 via one or more TRPs.

[0050] The terminal 120 and the terminal 130 are devices used by a user and communicate with the base station 110 via a wireless channel. In some cases, at least one of the terminal 120 and the terminal 130 may be operated without user participation. That is, at least one of the terminal 120 and the terminal 130 may be a device for performing machine type communication (MTC) and may not be carried by a user. Each of the terminal 120 and the terminal 130 may be referred to as a "user equipment (UE)", "mobile station", "user station", "customer terminal equipment (CPE)", "remote terminal", "wireless terminal", "electronic device", "user equipment" or other terms having equivalent technical meanings as well as a terminal.

[0051] The base station 110, the terminal 120, and the terminal 130 may transmit and receive radio signals in a millimeter wave (mmWave) frequency band (e.g., 28 GHz, 30 GHz, 38 GHz, or 60 GHz). In this case, in order to improve the channel gain, the base station 110, the terminal 120, and the terminal 130 may perform beamforming. Beamforming may include transmit beamforming and receive beamforming. That is, the base station 110, the terminal 120, and the terminal 130 may assign directivity to a transmitted signal or a received signal. To this end, the base station 110 and the terminal 120 and the terminal 130 may select service beams 112, 113, 121, and 131 through a beam search or beam management process. After selecting the service beams 112, 113, 121, and 131, subsequent communications may be performed via resources that are in a quasi-co-location (QCL) relationship with resources that transmit the service beams 112, 113, 121, and 131.

[0052] If a large-scale characteristic of a channel carrying symbols on a first antenna port can be inferred from a channel carrying symbols on a second antenna port, then it can be determined that the first antenna port and the second antenna port are in a QCL relationship. For example, the large-scale characteristic may include at least one of delay spread, Doppler spread, Doppler shift, average gain, average delay, and spatial receiver parameters.

[0053] In the following, a cell may correspond to a carrier frequency in the present disclosure. A plurality of cells may be classified according to the supported frequencies and the area of ​​the covered sectors. In addition, a cell may indicate an area that a single base station may cover. A base station may cover a cell, or may cover a plurality of cells. "Base station" may be used as a term including a cell, or "cell" may be used as a term referring to a base station.

[0054] Figure 2 The configuration of a base station in a wireless communication system according to an embodiment of the present disclosure is shown. Figure 2The configuration shown in may be regarded as the configuration of the base station 110. Hereinafter, the terms "unit", "device" and the like denote a unit for processing at least one function or operation and may be implemented as hardware, software or a combination thereof.

[0055] Reference Figure 2 , the base station 110 includes a wireless communication unit 210 , a backhaul communication unit 220 , a storage unit 230 , and a controller 240 .

[0056] The wireless communication unit 210 can perform the function of sending and receiving signals via a wireless channel. For example, the wireless communication unit 210 can perform the conversion function between the baseband signal and the bit stream according to the physical layer standard of the system. For example, in the case of data transmission, the wireless communication unit 210 can generate complex symbols by encoding and modulating the transmission bit stream. In the case of data reception, the wireless communication unit 210 can restore the received bit stream by demodulating and decoding the baseband signal. In addition, the wireless communication unit 210 can up-convert the baseband signal into a radio frequency (RF) band signal, and then send it via an antenna, and can down-convert the RF band signal received via the antenna into a baseband signal.

[0057] To this end, the wireless communication unit 210 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. In addition, the wireless communication unit 210 may include multiple transmission / reception paths. In addition, the wireless communication unit 210 may include at least one antenna array including multiple antenna elements. In terms of hardware, the wireless communication unit 210 may include a digital unit and an analog unit, and the analog unit may include multiple subunits according to operating power, operating frequency, etc.

[0058] The wireless communication unit 210 may transmit and receive signals. For example, the wireless communication unit 210 may transmit synchronization signals, reference signals, system information, messages, control information, data, etc. The wireless communication unit 210 may also perform beamforming. The wireless communication unit 210 may apply beamforming weights to the signals so as to assign directivity to the signals to be transmitted / received according to the settings of the controller 240.

[0059] The wireless communication unit 210 transmits and receives signals as described above. Therefore, all or some of the wireless communication unit 210 may be referred to as a "transmitter," "receiver," or "transceiver." In the following description, transmission and reception performed via a wireless channel will be used as a meaning including the processing performed by the wireless communication unit 210 as described above.

[0060] The backhaul communication unit 220 provides an interface for communicating with other nodes in the network. That is, the backhaul communication unit 220 converts a bit stream sent from the base station 110 to another node (e.g., another access node, another base station, an upper node, or a core network) into a physical signal, and converts a physical signal received from another node into a bit stream.

[0061] The storage unit 230 stores data such as basic programs, application programs, and configuration information for the operation of the base station 110. The storage unit 230 may be configured as a volatile memory, a non-volatile memory, or a combination thereof. In addition, the storage unit 230 provides the stored data at the request of the controller 240.

[0062] The controller 240 controls the overall operation of the base station 110. For example, the controller 240 sends and receives signals via the wireless communication unit 210 or the backhaul communication unit 220. The controller 240 writes data to the storage unit 230 or reads data from the storage unit 230. In addition, the controller 240 may perform the functions of the protocol stack required by the communication standard. To this end, the controller 240 may include at least one processor. According to various embodiments, the controller 240 may perform control according to various embodiments so that the base station 110 performs the operations to be described later.

[0063] Figure 3 A configuration of a terminal in a wireless communication system according to an embodiment of the present disclosure is shown. Figure 3 The configuration shown in may be regarded as the configuration of the terminal 120. Hereinafter, the terms "unit", "device" and the like indicate a unit for processing at least one function or operation and may be implemented by hardware, software or a combination thereof.

[0064] Reference Figure 3 The terminal 120 includes a communication unit 310 , a storage unit 320 and a controller 330 .

[0065] The communication unit 310 performs the function of sending and receiving signals via a wireless channel. For example, the communication unit 310 can perform the conversion function between the baseband signal and the bit stream according to the physical layer standard of the system. For example, in the case of data transmission, the communication unit 310 can generate complex symbols by encoding and modulating the transmission bit stream. In the case of data reception, the communication unit 310 can restore the received bit stream by demodulating and decoding the baseband signal. In addition, the communication unit 310 can up-convert the baseband signal to an RF band signal, and then send it via an antenna, and can down-convert the RF band signal received via the antenna to a baseband signal. For example, the communication unit 310 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc.

[0066] In addition, the communication unit 310 may include multiple transmit / receive paths. In addition, the communication unit 310 may include at least one antenna array including multiple antenna elements. In terms of hardware, the communication unit 310 may include digital circuits and analog circuits {e.g., radio frequency integrated circuits (RFIC)}. The digital circuits and analog circuits may be implemented as a single package. In addition, the communication unit 310 may include multiple RF chains. The communication unit 310 may perform beamforming. The communication unit 310 may apply beamforming weights to the signal so that directivity is assigned to the signal to be sent / received according to the setting of the controller 330.

[0067] In addition, the communication unit 310 can send and receive signals. For example, the communication unit 310 can receive synchronization signals, reference signals, system information, messages, control information, data, etc.

[0068] In addition, the communication unit 310 may include different communication modules to process signals in frequency bands different from each other. In addition, the communication unit 310 may include multiple communication modules that support a variety of different wireless access technologies. For example, different wireless access technologies may include low-power Bluetooth (BLE), Wi-Fi, Wi-Fi Gigabyte (WiGig), cellular networks {e.g., long-term evolution (LTE) or new radio (NR)}, etc. In addition, different frequency bands may include ultra-high frequency (SHF) (e.g., 2.5 GHz or 5 GHz) bands and millimeter wave (e.g., 38 GHz or 60 GHz) bands.

[0069] As described above, the communication unit 310 transmits and receives signals. Therefore, all or some of the communication unit 310 may be referred to as a "transmitter," "receiver," or "transceiver." In the following description, transmission and reception performed via a wireless channel will be used as a meaning including the processing performed by the communication unit 310 as described above.

[0070] The storage unit 320 may store data such as basic programs for the operation of the terminal 120, application programs, and data such as configuration information. The storage unit 320 may be configured as a volatile memory, a non-volatile memory, or a combination thereof. In addition, the storage unit 320 provides the stored data at the request of the controller 330. According to various embodiments, the storage unit 320 may store synchronization information. The synchronization information may include a carrier frequency (i.e., synchronization information on each CC). In addition, according to various embodiments, the storage unit 320 may store beam information. The beam information may be related to the CC. According to an embodiment, the beam information may include a group of beams. According to various embodiments, the storage unit 320 may include information related to the physical location of the cell (e.g., timing advance (TA) information). According to various embodiments, the storage unit 320 may include statistical information related to synchronization (e.g., synchronization variation).

[0071] The controller 330 controls the overall operation of the terminal 120. For example, the controller 330 sends and receives signals via the communication unit 310. The controller 330 writes data to the storage unit 320 or reads data from the storage unit 320. The controller 330 can perform the functions of the protocol stack required by the communication standard. To this end, the controller 330 may include at least one processor or microprocessor, or may be a part of a processor. In addition, the communication unit 310 and a part of the controller 330 may be referred to as a "CP". The controller 330 may include various modules for performing communication.

[0072] According to various embodiments, the controller 330 may include: a synchronization acquirer 331 for acquiring synchronization from a signal of a cell; a synchronization success determiner 333 for determining whether a cell is in synchronization or out of synchronization according to whether the synchronization of the cell satisfies a predetermined condition; a synchronization restorer 335 for restoring the synchronization of the cell according to the synchronization recovery process of the present disclosure and determining whether the synchronization of the cell succeeds or fails; and a synchronization information manager 337 for controlling the synchronization information of each cell or each beam. The synchronization acquirer 331, the synchronization success determiner 333, the synchronization restorer 335, and the synchronization information manager 337, which are a set of instructions or codes stored in the storage unit 320, may be instructions / codes at least temporarily residing in the controller 330, a storage space storing instructions / codes, a part of a circuit constituting the controller 330, or a module for performing the functions of the controller 330. According to various embodiments, the controller 330 may perform control so that the terminal performs operations according to various embodiments described below.

[0073] Although not in Figure 3As shown in the figure, in some embodiments, the terminal may further include separate hardware, such as a free running counter (FRC). FRC is a component that provides a reference value indicating the cell time. The terminal can use FRC and cell timer for each carrier to determine the success or failure of synchronization of each carrier, and compensate for the synchronization of a specific cell based on the synchronization of another cell. In this case, FRC can be connected to each cell timer to provide a reference value. In some embodiments, the device also includes a free running counter (FRC), which is configured to provide a reference value indicating the cell time.

[0074] Figure 3 The configuration of the terminal shown is only an example of the terminal, and the terminal is not limited thereto. That is, according to various embodiments, some configurations may be added, excluded or modified. For example, the synchronization success determiner 333 of the controller 330 may be implemented as an independent configuration for each cell configured for CA. For example, the above-mentioned FRC may be functionally implemented as a component of the controller 330.

[0075] Figure 4A A configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure is shown.

[0076] Figure 4B A configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure is shown.

[0077] Figure 4C A configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure is shown. FIG. 4A to FIG. 4C Shows Figure 2 The wireless communication unit 210 or Figure 3 An example of a detailed configuration of the communication unit 310 in FIG. More specifically, FIG. 4A to FIG. 4C Shown as Figure 2 The wireless communication unit 210 or Figure 3 A component for performing beamforming as a part of the communication unit 310.

[0078] Reference Figure 4A , the wireless communication unit 210 or the communication unit 310 includes an encoder / modulator 402 , a digital beamforming unit 404 , a plurality of transmission paths 406 - 1 to 406 -N, and an analog beamforming unit 408 .

[0079] The encoder / modulator 402 performs channel coding. At least one of a low density parity check (LDPC) code, a convolutional code, and a polarization code may be used for channel coding. The encoder / modulator 402 generates modulation symbols by performing constellation mapping.

[0080] The digital beamforming unit 404 performs beamforming on the digital signal (e.g., modulation symbol). To this end, the digital beamforming unit 404 multiplies the modulation symbol by a beamforming weight. The beamforming weight can be used to change the amplitude and phase of the signal, and can be referred to as a "precoding matrix", "precoder", etc. The digital beamforming unit 404 outputs the modulation symbol after digital beamforming to multiple transmission paths 406-1 to 406-N. In this case, according to a multiple-input multiple-output (MIMO) transmission scheme, the modulation symbol can be multiplexed, or the same modulation symbol can be provided to multiple transmission paths 406-1 to 406-N.

[0081] Multiple transmission paths 406-1 to 406-N convert the digital signal after digital beamforming into an analog signal. To this end, each of the multiple transmission paths 406-1 to 406-N may include an inverse fast Fourier transform (IFFT) operator, a cyclic prefix (CP) inserter, a DAC, and an up-converter. The CP inserter is intended for orthogonal frequency division multiplexing (OFDM) schemes and can be excluded when other physical layer schemes {e.g., filter bank multi-carrier (FBMC)} are applied. That is, multiple transmission paths 406-1 to 406-N provide independent signal processing processes for multiple streams generated by digital beamforming. However, according to an embodiment, some components in the multiple transmission paths 406-1 to 406-N may be used together.

[0082] The analog beamforming unit 408 performs beamforming on the analog signal. To this end, the digital beamforming unit 404 multiplies the analog signal by the beamforming weight. The beamforming weight is used to change the amplitude and phase of the signal. More specifically, the analog beamforming unit 408 can perform beamforming based on the connection structure between the multiple transmission paths 406-1 to 406-N and the antennas, such as Figure 4B or Figure 4C Configuration shown.

[0083] refer to Figure 4B , the signal input to the analog beamforming unit 408 is processed by phase / amplitude conversion and amplification operations, and then sent through the antenna. At this time, the signals of each path are sent through different groups of antennas (i.e., antenna arrays). Regarding the processing of the signal input through the first path, the signal is converted into a signal stream with the same or different phases / amplitudes by the phase / amplitude converters 412-1-1 to 412-1-M, amplified by the amplifiers 414-1-1 to 414-1-M, and then sent through the antenna.

[0084] Reference Figure 4C, the signal input to the analog beamforming unit 408 is processed by phase / amplitude conversion and amplification operations, and then sent through the antenna. At this time, the signals of each path are sent through the same group of antennas (i.e., antenna arrays). Regarding the processing of the signal input through the first path, the signal is converted into a signal stream with the same or different phases / amplitudes by phase / amplitude converters 412-1-1 to 412-1-M, and amplified by amplifiers 414-1-1 to 414-1-M. In addition, the amplified signals are summed by adders 416-1-1 to 416-1-M to be sent through an antenna array based on antenna elements, and then sent through the antenna.

[0085] Figure 4B An example is shown where each transmission path uses a separate antenna array. Figure 4C An example in which transmission paths share one antenna array is shown. However, according to another embodiment, some transmission paths may use independent antenna arrays, and the remaining transmission paths may share one antenna array. According to another embodiment, a structure that adaptively changes according to the situation may be used by applying a switchable structure between the transmission path and the antenna array.

[0086] In next generation communication system standards such as pre-5G or new radio (NR), operation with shorter transmission time intervals (TTIs) is being considered. As TTI becomes shorter, the length of the cyclic prefix (CP) in the symbol and the symbol become shorter, which may increase synchronization failures. In addition, because the impact of frequency selectivity increases due to the increase in transmission bandwidth, synchronization between carrier frequencies may be destroyed. In addition, because beamforming caused by transmission in high frequency bands is supported, synchronization further varies according to the physical location of the base station providing the cell.

[0087] Therefore, synchronization needs to be more strictly controlled in future communication systems. If a radio link failure (RLF) is declared and time synchronization is restored through RRE {Radio Resource Control (RRC) Connection Reestablishment} for each synchronization failure, data transmission / reception is interrupted during RRE execution, thereby degrading the user experience of communication quality, such as interruption of streaming services or degradation of quality of service (QoS). In addition, since additional processes such as a process of searching for a new beam (e.g., beam search or beam scanning) are required in the standard supporting beamforming, the communication quality may be further degraded.

[0088] Therefore, hereinafter, a method for recovering synchronization of an out-of-sync cell based on synchronization of a cell in synchronization even when the cell is out of synchronization will be described instead of immediately performing a reconnection process such as RRE. Figure 5 Describes the method used to resume synchronization.

[0089] Figure 5 An example of synchronization recovery according to an embodiment of the present disclosure is shown. The terminal may perform carrier aggregation (CA) including multiple component carriers (CCs). CC is a frequency unit of a service cell constituting CA and may be referred to as "carrier frequency", "carrier frequency band", "carrier", etc. In the following, for ease of description, CC will be referred to as "carrier".

[0090] Reference Figure 5 , the terminal can perform CA through four carriers (first carrier 511, second carrier 512, third carrier 513 and fourth carrier 514). The terminal can send or receive data through four carriers. In order to operate four carriers, the terminal needs to successfully obtain synchronization of each of the four carriers.

[0091] The terminal may receive a synchronization signal. For example, the terminal may receive a physical synchronization signal (PSS) from a base station. The terminal may obtain the cell time of the cell based on the synchronization signal. The cell time refers to the synchronization of the carrier. That is, determining the synchronization of the carrier means determining the cell time of the cell providing the corresponding carrier. The terminal may determine whether the carrier synchronization is successful or failed from the cell time. Hereinafter, an example will be described in which the synchronization of the second carrier 512 and the fourth carrier 514 performed by the terminal is successful but the synchronization of the first carrier 511 and the third carrier 513 fails. In the present disclosure, "successful synchronization" refers to the case where the carrier becomes synchronized {the error between each resource boundary (e.g., symbol boundary) of the base station and the resource boundary of the terminal is within a predetermined range}, and "failed synchronization" refers to the case where the carrier becomes unsynchronized {the error between each resource boundary (e.g., symbol boundary) of the base station and the resource boundary of the terminal exceeds a predetermined range}.

[0092] The terminal needs to restore the synchronization of the unsynchronized cell. If the terminal does not restore the synchronization of the unsynchronized cell, the terminal will continuously decode the signal at the wrongly obtained cell time, so that the terminal cannot correctly receive control information or data, and additional power is wasted. In addition, if a reconnection such as an RRE process or deletion / addition of an Scell ​​is performed in order to regain synchronization, data interruption occurs, resulting in a decrease in communication quality.

[0093] According to various embodiments, the terminal can obtain synchronization of carriers of unsynchronized cells (e.g., the first carrier 511 and the third carrier 513) based on the synchronization of carriers of cells in synchronization (e.g., the second carrier 512 and the fourth carrier 514). The process of obtaining synchronization of carriers of unsynchronized cells based on the synchronization of carriers of cells in synchronization is referred to as "synchronization compensation" in the present disclosure. For example, the terminal can obtain compensated synchronization 521 of the first carrier 511 through synchronization compensation based on the synchronization of the second carrier 512. In addition, the terminal can obtain compensated synchronization 523 of the third carrier 513 through synchronization compensation based on the synchronization of the fourth carrier 514.

[0094] The terminal can determine whether the synchronization of each carrier is successful after synchronization compensation. The terminal can determine whether the synchronization of the unsynchronized carrier is restored (hereinafter, referred to as "synchronization recovery"). That is, the terminal can determine whether to restore the synchronization of the unsynchronized carrier based on the synchronization of the unsynchronized carrier obtained by synchronization compensation. In other words, the terminal can determine whether the carrier that was originally unsynchronized becomes synchronized through synchronization compensation. For example, the terminal can determine that the synchronization of the first carrier 511 is successful through compensated synchronization 521. In addition, the terminal can determine that the synchronization of the third carrier 513 is successful through compensated synchronization 523.

[0095] If all carriers configured for CA become synchronized, the terminal can send or receive data through CA. Figure 5 Not shown in the figure, if the synchronization of some carriers is not restored, the terminal may perform RRE or perform Scell ​​deletion / addition.

[0096] As reference Figure 5 As described above, the terminal can restore the synchronization of the carrier by synchronization compensation. When CA is set, the terminal can perform synchronization compensation independently for each carrier. Figure 5 , but the present disclosure is not limited thereto. The present disclosure may be applied to any communication process for determining the synchronization of a carrier by performing synchronization compensation based on the synchronization of another carrier. For example, in the case where a specific carrier is not synchronized, the terminal may determine the synchronization of the specific carrier based on the synchronization information of another carrier obtained by inter-frequency measurement. Figure 6 and Figure 7 The operation of a terminal for synchronization compensation or synchronization recovery is described.

[0097] Figure 6 A flow chart of a terminal for synchronous recovery according to an embodiment of the present disclosure is shown. The terminal may be Figure 1 The terminal 120 in.

[0098] Reference Figure 6The terminal may obtain first synchronization of a first carrier in synchronization in operation 601. The terminal may identify the first carrier in synchronization. The terminal may determine whether synchronization of each carrier is successful or failed, so as to identify the first carrier in synchronization.

[0099] The terminal may determine whether each carrier is in synchronization. The terminal may determine whether each cell is in synchronization or out of synchronization. The terminal may obtain synchronization of each of the plurality of carriers of the terminal, and may determine whether synchronization of each cell is successful or failed based on the obtained synchronization. Synchronization acquisition and determination of synchronization success or failure may be performed independently for each carrier.

[0100] The terminal may determine whether the carrier synchronization is successful or failed. For example, the terminal may determine whether the synchronization of the corresponding cell is successful or failed based on whether the synchronization signal correlation value is detected during the time corresponding to the synchronization. In addition, the terminal may determine whether the synchronization of the corresponding cell is successful or failed based on, for example, whether the time corresponding to the synchronization is within a predetermined range. In addition, the terminal may determine whether the synchronization of the corresponding cell is successful or failed based on, for example, the channel quality.

[0101] At least one carrier in synchronization among the multiple carriers may include a first carrier. The terminal may obtain a first synchronization of the first carrier. Acquisition of the first synchronization means determining the cell time of the first cell. The cell time refers to the time when a signal (e.g., a synchronization signal) of a cell is sent within an absolute time period (e.g., 10 ms). The terminal may determine the cell time of the first cell based on the synchronization signal sent by the first cell. For example, the terminal may receive the PSS sent by the first cell twice to determine the cell time of the first cell. The first synchronization may be the cell time of the first cell obtained when determining whether the synchronization succeeds or fails.

[0102] In operation 603, the terminal may determine a second synchronization of the unsynchronized second carrier based on the first synchronization. The terminal may identify the unsynchronized second carrier. When the synchronization success or failure of each carrier is determined in operation 601, the terminal may identify at least one unsynchronized carrier from the plurality of carriers. The at least one unsynchronized carrier includes the second carrier.

[0103] The terminal may perform synchronization compensation based on the first synchronization to determine the second synchronization. The synchronization compensation includes an operation of determining a synchronization to be applied as compensation for the second synchronization. As described above, the terminal identifies at least one carrier in synchronization for the synchronization compensation. The at least one carrier in synchronization includes the first carrier.

[0104] According to various embodiments, the terminal may perform synchronization compensation based on synchronization of at least one carrier in synchronization. That is, the terminal may use all carriers in synchronization to perform synchronization compensation. Alternatively, according to various embodiments, the terminal may perform synchronization compensation based on synchronization of some carriers among one or more carriers in synchronization. That is, the terminal may use some carriers (hereinafter referred to as "compensation carriers") suitable for synchronization compensation among the carriers in synchronization to perform synchronization compensation, rather than using all carriers in synchronization to perform synchronization compensation.

[0105] The terminal may perform synchronization compensation based on synchronization of the compensation carrier. The terminal may identify the compensation carrier in one or more synchronization carriers in synchronization. The compensation carrier may include a first carrier. In some embodiments, the terminal may identify the first carrier based on a metric for at least one carrier in synchronization. For example, the terminal may identify the first carrier based on a synchronization gradient in one or more carriers in synchronization. In some other embodiments, the terminal may identify the first carrier from one or more carriers in synchronization based on an unsynchronized second carrier. For example, a base station in a second cell providing a second carrier may be associated with the first cell. In addition, for example, the second carrier may be adjacent to the frequency band of the first cell. In addition, for example, the beam used for the second carrier may be the same as the beam used for the first carrier.

[0106] The terminal may apply an average weight or individual weights to the synchronization of one or more carriers or one or more compensation carriers in synchronization, thereby performing synchronization compensation. The individual weights may be determined based on the frequency characteristics, statistical characteristics, and physical characteristics of each carrier. The terminal may determine the second synchronization of the second carrier through synchronization compensation. For example, the terminal may average the synchronization of three compensation carriers to determine the compensated synchronization. The terminal may determine the compensated synchronization as the second synchronization of the unsynchronized second carrier. That is, the terminal may determine the cell time corresponding to the compensated synchronization as the cell time of the second carrier.

[0107] In some embodiments, the at least one processor is further configured to apply the respective weights to the first synchronization.

[0108] In operation 605, the terminal may perform communication based on the second synchronization. The terminal may determine whether the synchronization of the second carrier has been restored based on the second synchronization. In other words, the terminal may determine whether the synchronization of the second carrier is successful or failed based on the second synchronization. For example, the terminal may determine whether the synchronization of the second cell providing the second carrier is successful or failed based on whether a synchronization signal correlation value is detected during the time period corresponding to the second synchronization. In addition, the terminal may determine whether the synchronization of the second cell is successful or failed based on, for example, whether the time corresponding to the second synchronization is within a predetermined range. In addition, the terminal may determine whether the synchronization of the second cell is successful or failed based on, for example, the channel quality according to the second synchronization signal.

[0109] According to an embodiment, the condition for determining synchronization success or failure in operation 605 may be the same or similar to the condition for determining synchronization success or failure of each cell in operation 601. In addition, although the parameters for determining the condition are the same between operation 601 and operation 605, the threshold for determining whether a specific condition is satisfied may be different. According to another embodiment, the condition for determining synchronization success or failure in operation 605 may be independent of the condition for determining synchronization success or failure of each cell in operation 601.

[0110] If the synchronization of the second carrier is successful, the terminal can perform communication. If there are other carriers that are not synchronized in addition to the second carrier, the terminal can determine whether to restore the synchronization of the other carriers that are not synchronized. If the synchronization of all carriers set for the terminal is restored, the terminal can perform communication. If the synchronization of the second carrier fails, the terminal can re-establish a connection with the base station to re-detect the synchronization of the second cell. For example, the terminal can perform RRE. In addition, if the second cell is, for example, an Scell, the terminal can perform deletion and addition of the Scell.

[0111] According to various embodiments of the present disclosure, when the synchronization of a carrier in synchronization is changed, the compensated synchronization determined for an unsynchronized carrier may also be changed. That is, as the synchronization of a carrier in synchronization (e.g., the first synchronization in operation 601) changes, the synchronization determination value of the carrier performed using synchronization compensation (e.g., the second synchronization in operation 603) is also changed, thereby verifying whether the present disclosure can be implemented. According to some embodiments, the cell time of an unsynchronized carrier {e.g., a primary component carrier (PCC)} may be changed to the cell time of a carrier in synchronization {e.g., a secondary component carrier (SCC)}. The implementation of the present disclosure may also be verified based on the detection of the above-mentioned change operation.

[0112] Already referenced Figure 6 The synchronous compensation process is described in detail. Figure 7An operation flow of a terminal for determining whether synchronization of carriers constituting CA is successful or failed according to the synchronization compensation process of the present disclosure is described.

[0113] Figure 7 A flow chart of a terminal for determining whether synchronization in CA is successful or failed according to an embodiment of the present disclosure is shown. The terminal may be Figure 1 The terminal 120 in.

[0114] Reference Figure 7 , the terminal may determine the synchronization success or failure of each carrier in operation 701. The terminal may determine the synchronization success or failure for each carrier configured for CA of the terminal. The determination of the synchronization success or failure may be performed independently for each carrier. Fig. 8A and Figure 8B An example is described regarding a detailed determination of synchronization success or failure.

[0115] In operation 703, the terminal may determine whether there is an unsynchronized carrier. The terminal may determine whether there is an unsynchronized carrier among the carriers configured for the terminal based on the result obtained in operation 701. If there is at least one unsynchronized carrier, the terminal may perform operation 705. On the other hand, if there is no unsynchronized carrier, the terminal may perform operation 711.

[0116] In operation 705, the terminal may determine whether there is a carrier in synchronization. The terminal may determine whether there is a carrier in synchronization among the carriers configured for the terminal based on the result obtained in operation 701. If there is a carrier in synchronization, the terminal may perform operation 707. On the other hand, if there is no carrier in synchronization (i.e., if all carriers are out of synchronization), the terminal may perform operation 713. This is due to the fact that if another carrier that is out of synchronization is used to compensate for the synchronization of the carrier that is out of synchronization, the synchronization may be further deteriorated.

[0117] In operation 707, the terminal may perform synchronization compensation. The terminal may identify at least one compensation carrier from one or more carriers in synchronization. "Compensation carrier" refers to a carrier that provides synchronization obtained for synchronization compensation.

[0118] According to various embodiments, the terminal may identify at least one compensation carrier based on the unsynchronized carrier. In some embodiments, the compensation carrier may be within a threshold range in the frequency domain of the unsynchronized carrier. That is, the compensation carrier may be a carrier adjacent to the unsynchronized carrier. The impact of frequency selectivity increases due to the increase in bandwidth. Since synchronization may vary with a larger frequency difference between carriers, the terminal may determine a carrier adjacent to the unsynchronized carrier as a compensation carrier.

[0119] In some embodiments, the compensation carrier may be associated with the beam of the unsynchronized carrier. For example, the compensation carrier may be provided to the terminal via the same beam as the beam of the unsynchronized carrier. The beam may be a terminal beam. The terminal may improve the accuracy of synchronization compensation in the carrier corresponding to the same beam information by applying synchronization information to each other. As another example, even if the compensation carrier is different from the beam of the unsynchronized carrier, it may be provided to another terminal via another beam in the same beam group. The beam group may be a group of beams with similar beam directions. This is due to the fact that because the paths of the signals sent in the case of similar beam directions are similar, the similarity between synchronizations may be relatively high. Although described based on the beam of the terminal, information on the beam pair link or the beam of the base station may also be used to determine the compensation carrier. For example, the terminal may identify a carrier provided by the same beam of the same base station as the unsynchronized carrier in the carrier in synchronization as a compensation carrier.

[0120] In some embodiments, the compensation carrier may be associated with a base station that provides an unsynchronized carrier. That is, the terminal may identify the compensation carrier considering the physical arrangement of the cell. For example, the base station that provides the compensation carrier may be the same as the base station that provides the unsynchronized carrier. The terminal may identify the compensation carrier based on a timing advance group (TAG). As another example, the base station that provides the compensation carrier may be located within a predetermined physical range from the base station that provides the unsynchronized carrier. The terminal may identify the compensation carrier based on the TAG. This is due to the fact that if the physical locations of the base stations are the same or similar, the similarity between synchronizations may be increased.

[0121] According to various embodiments, the terminal may identify at least one compensation carrier according to the channel quality of each of one or more carriers in synchronization. The channel quality may be at least one of a signal to interference plus noise ratio (SINR), a carrier to interference plus noise ratio (CINR), a beam reference signal received power (BRSRP), a reference signal received power (RSRP), a reference signal received quality (RSRQ), a received signal strength indicator (RSRI), an error vector magnitude (EVM), a bit error rate (BER), and a block error rate (BLER). In the following, SINR will be described as an example of channel quality. In the present disclosure, high channel quality refers to a situation where a channel quality value related to the signal amplitude is large or a channel quality value related to the error rate is small. The higher the channel quality, the better the wireless communication environment can be provided.

[0122] In some embodiments, the terminal may identify a carrier with high channel quality as a compensation carrier. This is due to the fact that the higher the channel quality, the higher the reliability of the channel. For example, the terminal may measure the RSRP of the synchronization signal of each carrier. The terminal may identify the first N (N is an integer) carriers with high RSRP of the synchronization signal among the carriers in synchronization as compensation carriers.

[0123] In some other embodiments, the terminal may identify at least one compensation carrier among one or more carriers in synchronization based on the degree of change in synchronization. For example, the terminal may identify the carrier with the smallest degree of change in synchronization as the compensation carrier. This is due to the fact that the smallest degree of change means that the reliability of the obtained synchronization is high. As another example, if the synchronization change amount of the carrier in synchronization alternates between negative and positive numbers, the terminal may not identify the corresponding carrier as the compensation carrier. This is due to the fact that even if the carrier becomes synchronized, the reliability of the obtained synchronization may be low.

[0124] Although the conditions for identifying the compensation carrier have been described above, the present disclosure is not limited thereto. According to various embodiments, the terminal may identify at least one compensation carrier by combining two or more of the above conditions (eg, frequency domain, beam, base station, channel quality, etc.).

[0125] The terminal may determine the synchronization of the unsynchronized carrier based on the synchronization of each identified compensation carrier. For example, the terminal may determine the timing value (i.e., cell time) for the synchronization of the first carrier as the compensation carrier as the timing value for the synchronization of the unsynchronized second carrier. The terminal may decode the signal of the second carrier according to the subframe boundary of the first carrier. As another example, the terminal may determine the average value of the compensation carrier as the synchronization of the unsynchronized second carrier.

[0126] The terminal may determine the synchronization of the unsynchronized carriers, thereby performing synchronization compensation. If there are two or more unsynchronized carriers, the terminal may perform synchronization compensation for each unsynchronized carrier. In some embodiments, the terminal may use the carrier on which synchronization compensation is performed as a compensation carrier. The terminal may use the carrier on which synchronization compensation is performed as a compensation carrier to perform synchronization compensation on the unsynchronized carrier. In some other embodiments, the terminal may perform synchronization compensation on each unsynchronized carrier. In the following, reference will be made to Figures 9 to 11B An example of determining the synchronization compensation in detail is described.

[0127] In operation 709, the terminal may determine whether all carriers have become synchronized. The terminal may determine whether all carriers constituting the CA of the terminal have become synchronized. According to the result of operation 701, the terminal may skip the determination of the success or failure of synchronization of the carrier in synchronization. According to the result of operation 701, the terminal may re-execute the determination of the success or failure of synchronization of the carrier that is not synchronized. The terminal may determine the success or failure of synchronization of the carrier that is not synchronized based on the synchronization determined according to the synchronization compensation in operation 707. In other words, the terminal may determine whether to restore the synchronization of the carrier that is not synchronized according to the synchronization compensation in operation 707. If all carriers are in synchronization, the terminal may perform operation 711. On the other hand, if there is a carrier that is not synchronized, the terminal may perform operation 713.

[0128] In operation 711, the terminal may determine that the synchronization of CA is successful. The terminal may perform CA. The terminal may send or receive data via the configured carrier. In operation 713, the terminal may determine that the synchronization of CA fails. In the case of the synchronization failure of CA, in some embodiments, the terminal may perform deletion / modification of the Scell, or may perform a new reconnection process. In some other embodiments, the terminal may re-execute the synchronization compensation process shown. In addition, in some other embodiments, the terminal may maintain the connection with the base station until the number of unsynchronized carriers exceeds a specified value. Reference will be made to Fig.12 An example of determining whether to resume synchronization is described in detail.

[0129] although Figure 7 Operations 703 to 705 are shown to be performed after determining the success or failure of synchronization of each carrier in operation 701, but the present disclosure is not limited thereto. The terminal may perform operation 703 even if only one unsynchronized carrier is detected, or may perform operation 705 even if only one synchronized carrier is detected.

[0130] Fig. 8A FIG. 4 shows a flow chart of a terminal for determining whether synchronization of each carrier is successful or failed according to an embodiment of the present disclosure. The terminal may be Figure 1 In the following, the terminal 120 can be Figure 7 Operation 701 in the Fig. 8A The process of determining the synchronization success or failure of each carrier.

[0131] Reference Fig. 8A In operation 801, the terminal may determine whether a maximum correlation value condition of a carrier is satisfied. The maximum correlation value condition indicates a condition for detecting a synchronization success of a carrier based on a maximum correlation value of a synchronization sequence.

[0132] Since the terminal does not know the time when the synchronization signal is received, the terminal can perform a correlation operation per unit time. The synchronization signal may include a sequence. For example, the synchronization signal may include a PSS sequence. As another example, the synchronization signal may include an SSS sequence. The terminal may perform a correlation operation based on a sequence for the synchronization signal (hereinafter referred to as a "synchronization sequence"). The terminal may calculate multiple correlation values ​​by correlation operation using the synchronization sequence. The terminal may determine the maximum correlation value as a peak value among multiple correlation values. The terminal may calculate the maximum correlation value exceeding the correlation threshold by a correlation operation within a unit time of sending the synchronization sequence. This is due to the fact that a correlation operation is performed between the same synchronization sequences, thereby deriving a peak value from the correlation value. The terminal may determine the unit time with the maximum correlation value as the synchronization time by a correlation operation. At the same time, if the synchronization fails, although the maximum correlation value is the maximum correlation value among the calculated correlation values, the maximum correlation value may be equal to or less than the correlation threshold. The terminal may determine whether the synchronization fails by comparing the maximum correlation value with the correlation threshold. For example, the terminal may determine whether the maximum correlation value satisfies the following equation.

[0133] Corr max，m >C t Equation 1

[0134] In Equation 1, "m" represents an index indicating a carrier. max,m It can be the maximum correlation value of the carrier with index m. t Can be a correlation threshold.

[0135] The terminal can determine whether the carrier synchronization is successful or failed based on whether the maximum correlation value of the carrier does not exceed the correlation threshold value and whether it is continuously detected for more than a threshold number of times. The threshold number of times can be preset as a fixed value (for example, twice), or can be set to be variable depending on the channel state or user input. The terminal can determine whether the maximum correlation value condition is met based on whether the maximum correlation value of the carrier does not exceed the correlation threshold value and whether it is detected for more than a threshold number of times.

[0136] If the maximum correlation value does not exceed the correlation threshold for a number of consecutive times equal to or greater than the threshold number of times, the terminal may determine that the maximum correlation value condition is met. The terminal may perform operation 803. If the maximum correlation value does not exceed the correlation threshold for a number of consecutive times less than the threshold number of times, the terminal may determine that the maximum correlation value condition is not met. According to an embodiment, if the threshold is 1, the terminal may determine that the maximum correlation value condition is not met in response to a detection indicating that the maximum correlation value does not exceed the correlation threshold. The terminal may perform operation 809.

[0137] In operation 803, the terminal may determine whether the synchronization time condition of the carrier is met. The synchronization time condition refers to a condition for detecting successful carrier synchronization based on the obtained carrier synchronization (i.e., cell time). The terminal may determine the cell time of the carrier as the synchronization of the carrier. The terminal may determine whether the cell time is within a predetermined range. The cell time may be determined using a cell time offset (CTO) from a reference value. The terminal may determine whether the synchronization time condition is met based on whether the cell time offset of the corresponding carrier is within a specific range. For example, the terminal may determine whether the cell time offset of the first carrier satisfies the following equation.

[0138]

[0139] In Equation 2, "m" represents an index indicating a carrier. CTO,m represents the cell time offset of the first carrier, t s1 and t s2 Respectively represent the upper and lower limits of a specific range of synchronization time conditions.

[0140] If the cell time offset is within a certain range, the terminal can determine that the synchronization time condition is met. The terminal can perform operation 805. If the cell time offset exceeds a certain range, the terminal can determine that the synchronization time condition is not met. This is due to the fact that if the synchronization obtained periodically (for example, with a period of 5ms) exceeds a certain range, the reliability of the synchronization of the corresponding carrier is reduced. The terminal can perform operation 809.

[0141] In operation 805, the terminal may determine whether a channel quality condition of the carrier is satisfied. The channel quality condition refers to a condition for detecting successful synchronization of the carrier based on the obtained channel quality of the carrier. The terminal may determine whether the channel quality of the carrier is higher than a predetermined benchmark (e.g., a reference value). For example, the terminal may determine whether the BLER of the physical downlink shared channel (PDSCH) satisfies the following equation.

[0142] BLER m <R BLER Equation 3

[0143] In Equation 3, "m" represents an index indicating a carrier. BLER m Represents the BLER of the PDSCH of the carrier with index m. BLER If the BLER of the PDSCH is less than the threshold, the terminal can determine that the channel quality condition is met.

[0144] If the channel quality is higher than the predetermined reference, the terminal may determine that the channel quality condition is satisfied. The terminal may perform operation 807. On the other hand, if the channel quality condition is lower than the predetermined reference, the terminal may perform operation 809.

[0145] In operation 807, the terminal may determine that synchronization of the carrier is successful. In operation 809, the terminal may determine that synchronization of the carrier fails. According to various embodiments, the terminal may perform operations 801 to 809 for each carrier set for CA of the terminal. The terminal may determine whether synchronization of each carrier is successful or failed, respectively.

[0146] Already referenced Fig. 8A Methods for determining the success or failure of synchronization for each carrier are described. Fig. 8A The sequential connection of the three conditions shown in is an example for determining synchronization success or failure, and the present disclosure is not limited to this. In other words, the terminal can determine the success or failure of carrier synchronization in various ways, such as using different sequences of the three conditions to determine the success or failure of carrier synchronization, using certain conditions to determine the success or failure of carrier synchronization, or by adding other conditions not shown to the above conditions to determine the success or failure of carrier synchronization. For example, if the synchronization time condition of the carrier is met, the terminal can determine that the synchronization of the carrier is successful without determining other conditions. As another example, if the synchronization time condition of the carrier is met, and if the BLER of the PDSCH of the carrier is less than a threshold, the terminal can determine that the synchronization of the carrier is successful without determining the maximum correlation value condition.

[0147] The terminal determines whether each carrier is synchronized successfully or unsuccessfully, thereby obtaining synchronization of the carriers in synchronization. The terminal may perform synchronization compensation (hereinafter referred to as "early synchronization compensation") before determining that a specific carrier is out of synchronization. After determining whether each carrier is synchronized successfully or unsuccessfully, the early synchronization compensation is performed before synchronization compensation is performed, thereby reducing the compensation burden of synchronization compensation and providing fast synchronization recovery. That is, the terminal may perform synchronization compensation before performing synchronization compensation. Figure 7 The synchronization compensation is performed before the synchronization compensation in operation 707 in the embodiment. Figure 8B Describe an example of early synchronization compensation.

[0148] Figure 8B FIG. 4 shows a flow chart of a terminal for early synchronization compensation according to an embodiment of the present disclosure. The terminal may be Figure 1 Terminal 120 in the terminal. Terminal execution Fig. 8A Operation 801 of the process for determining synchronization success or failure for each carrier is shown.

[0149] Reference Figure 8B , the terminal may calculate a correlation value per unit time in operation 851. The terminal may calculate a correlation value per unit time using a synchronization sequence.

[0150] In operation 853, the terminal may determine whether the maximum correlation value exceeds the correlation threshold. The terminal may identify the correlation value of the current peak (i.e., the maximum correlation value). The terminal may determine whether the identified maximum correlation value exceeds the correlation threshold. The correlation threshold may be a threshold for identifying the peak that occurs using a correlation operation of the same or similar synchronization sequence. That is, if the maximum correlation value exceeds the correlation threshold, the terminal may determine that the synchronization of the carrier that sends the corresponding synchronization sequence is successful. The terminal may perform operation 865. On the other hand, if the maximum correlation value is equal to or less than the correlation threshold, the terminal may perform operation 855.

[0151] In operation 855, the terminal may determine whether synchronization compensation is available. The terminal may determine whether there is a carrier for synchronization compensation. This is due to the fact that if there is no carrier in synchronization, there is no input for performing synchronization compensation. Therefore, the terminal may determine whether there is a carrier in synchronization. For example, the terminal may determine a carrier whose maximum correlation value is equal to or greater than a correlation threshold as a synchronization carrier. The terminal may identify an index of a carrier satisfying equation 1 among a plurality of carriers set for the terminal.

[0152] In order to determine whether synchronization compensation is available, the maximum correlation value condition has been shown and described as an example of a condition for determining whether synchronization of each carrier is successful or failed. However, the terminal may also use other conditions (e.g., Fig. 8A The terminal may use the synchronization time condition in the synchronization compensation to identify the carrier in synchronization. If synchronization compensation is not available, the terminal may perform operation 865. If synchronization compensation is available, the terminal may perform operation 857.

[0153] In operation 857, the terminal may perform synchronization compensation. The terminal may perform early synchronization compensation. Figure 7 The early synchronization compensation which is the same as or similar to the synchronization compensation in operation 707 in FIG. 1 refers to a process of obtaining synchronization of an unsynchronized carrier based on synchronization of a carrier in synchronization.

[0154] The terminal may determine a compensation value (eg, Δt m , where "m" is the index of the unsynchronized carrier). The compensation value refers to a value used to compensate for the unsynchronized carrier. For example, the compensation value may be determined based on the synchronization average of one or more carriers in synchronization. As another example, the compensation value may be determined based on the synchronization of one or more carriers in synchronization. The terminal may apply the compensation value to the cell time of the unsynchronized carrier. For example, if the cell time offset of the previous frame of the unsynchronized carrier is t offset , then the terminal can determine the cell time offset in the current frame as t offset +Δt m .

[0155] In operation 859, the terminal may determine whether the synchronization compensation is successful. The terminal may determine whether the cell time offset after synchronization compensation is within a specific range. For example, the terminal may determine whether the cell time offset after synchronization compensation satisfies the following equation.

[0156]

[0157] In Equation 4, t offset represents the cell time offset in the previous frame, and Δt m Indicates the compensation value of the carrier with index m. s1 and t s2 Respectively represent the upper and lower limits of the range used for early synchronization compensation.

[0158] Although the synchronization time condition has been shown and described as an example of a condition for determining the success or failure of synchronization compensation, other conditions (e.g., Fig. 8A The terminal may use the channel quality condition in the synchronization compensation to identify the carrier in synchronization. If the synchronization compensation is successful, the terminal may perform operation 865. If the synchronization compensation fails, the terminal may perform operation 861.

[0159] In operation 861, the terminal may determine whether the number of times the maximum correlation value is less than the correlation threshold exceeds the threshold number of times. Operation 861 corresponds to Fig. 8A 801 in the example, and thus descriptions of the same or similar operations will be omitted. If the number of times that the maximum correlation value is less than the correlation threshold exceeds the threshold number of times, the terminal may perform operation 863. On the other hand, if the number of times that the maximum correlation value is less than the correlation threshold is equal to or less than the threshold number of times, the terminal may perform operation 865.

[0160] In operation 863, the terminal may determine that the maximum correlation value condition is not satisfied. The terminal may determine that carrier synchronization has failed. In operation 865, the terminal may determine that the maximum correlation value condition is satisfied. The terminal may determine that synchronization of the corresponding carrier is successful, or may determine whether carrier synchronization is successful or failed by further determining whether other conditions are satisfied.

[0161] Despite Figure 8B , an example of performing early synchronization compensation when determining whether the maximum correlation value condition is satisfied is described in , but the early synchronization compensation of the present disclosure can be performed even during determination of other conditions. Fig. 8A When determining whether the synchronization time condition is met in operation 803 in the embodiment, the terminal may perform early synchronization compensation. In addition, according to an embodiment, the terminal may perform early synchronization compensation multiple times under certain conditions instead of performing early synchronization compensation once.

[0162] Already referenced FIG. 8A to FIG. 8B An example of determining the success or failure of synchronization for each carrier is described. Figures 9 to 11B Operation and embodiments of a terminal for compensating for synchronization of unsynchronized carriers are described.

[0163] Fig. 9 FIG. 4 shows a flow chart of a terminal for synchronous compensation according to an embodiment of the present disclosure. The terminal may be Figure 1 The terminal 120 in. Fig. 9 Shows Figure 7 Operation 707 in .

[0164] Reference Fig. 9 , the terminal may obtain a first offset of a carrier in synchronization in operation 901. The offset is a cell time offset, which is a value indicating how much a cell timer for a responding carrier is offset from a reference timer (e.g., FRC). The various carriers set for the terminal may share a reference timer. The reference timer provides a reference value commonly applied to various carriers. The value of the cell timer of each carrier may indicate the actual cell time by an offset from the reference value. The first offset may be an offset of the cell time of a first carrier among one or more carriers in synchronization, the first carrier being at least one compensation carrier.

[0165] According to various embodiments, the first offset carrier may be a carrier using the same beam direction as that of the unsynchronized carrier. The terminal may identify the offset of the in-sync carrier, which uses the same beam as that of the unsynchronized carrier, as the first offset.

[0166] According to various embodiments, the first offset carrier may be within a predetermined range of the unsynchronized carrier in the frequency band. That is, the first offset carrier may be adjacent to the unsynchronized carrier in the frequency band. By using the synchronization of the adjacent carrier in the frequency band to compensate for the synchronization of the unsynchronized carrier, the impact of frequency selectivity can be reduced.

[0167] According to various embodiments, among the carriers in synchronization, the first offset carrier may be a carrier with high (good) channel quality. For example, among the carriers in synchronization, the first offset carrier may be a carrier with the smallest change in the change value of the cell timing. In addition, among the carriers in synchronization, the first offset carrier may be, for example, a carrier with the highest RSRQ. By compensating for the synchronization of the out-of-synchronization carrier using the synchronization of the carrier with high channel quality, synchronization compensation may be performed with high reliability.

[0168] In operation 903, the terminal may determine a second offset of the unsynchronized carrier based on the first offset. According to various embodiments, the terminal may use the first offset to determine the second offset of the unsynchronized carrier. For example, the terminal may apply the value of the first offset to the second offset of the unsynchronized carrier. That is, the second offset may be equal to the first offset. As another example, the terminal may determine the second offset by adding a compensation value between the carrier of the first offset and the carrier of the second offset to the first offset.

[0169] According to various embodiments, the terminal may use the offset value of the compensation carrier including the first offset to determine the offset of the unsynchronized second carrier. In some embodiments, the terminal may use the average value of the offset value to determine the second offset. In some other embodiments, the terminal may apply each weight to the offset value to determine the second offset. For example, the terminal may apply weights differently according to the proximity of each compensation carrier to the unsynchronized carrier in the frequency domain to determine the second offset. As another example, the terminal may apply weights differently according to the channel quality of each compensation carrier to determine the second offset. As another example, the terminal may apply weights differently according to the geographical proximity of each compensation carrier to the cell providing the unsynchronized carrier to determine the second offset. The geographical proximity may be determined based on at least one of TA, beam information, geographical information such as from a global positioning system (GPS), a cell identifier (ID), and statistical information.

[0170] Fig.10 An example of a timer of a terminal for synchronization compensation according to an embodiment of the present disclosure is shown. The terminal may be Figure 1 The terminal 120 in.

[0171] Reference Fig.10 , the terminal may include a reference timer 1010. The reference timer 1010 is intended to provide a common reference for each carrier of the terminal, and each cell timer may be configured to refer to the value of the reference timer 1010. Fig.10 The FRC as a reference timer is shown. That is, the FRC can be configured to provide a common reference value to the carrier of the terminal. The terminal can drive the FRC as long as it is turned on. The terminal can determine the synchronization time of the base station based on the FRC. The terminal can continuously increase the FRC value according to the number of samples. Generally, the FRC can be configured in the form of at least one of "number of frames", "number of subframes", "number of time slots" or "number of samples".

[0172] The value indicated by indicator 1015 may be an FRC value. The FRC indicator 1015 cycles in a specified period of time until the terminal is turned off. In some embodiments, the specified period may be 10 milliseconds (ms). The terminal may repeat the cycle indicator 1015 every 10 ms. The indicator 1015 may repeatedly indicate the FRC value in a specified period.

[0173] The terminal may include a cell timer. The terminal may include a cell timer for a carrier configurable for the terminal. For example, the terminal may include a first cell timer 1021 for a first carrier and a second cell timer 1022 for a second carrier. The first cell timer 1021 may include a first cell time indicator 1041. The first cell time indicator 1041 may indicate a cell time K of a first cell of the first carrier. 1 The second cell timer 1022 may include a second cell time indicator 1042. The second cell time indicator 1042 may indicate a cell time K of the second cell of the second carrier. 2 The cell timer may repeatedly indicate the cell time at each specified period. The specified period may be set equal to the specified period of the FRC. In other words, the cell timer may have the same period value as the FRC, except that the starting point is different therefrom.

[0174] The CTO may be defined as a value relative to the FRC calculated by the synchronization signal search of the base station. The first cell time indicator 1041 may indicate a state where the first CTO 1031 is offset from the value of the FRC. That is, the first cell time indicator 1041 may indicate a position where the first CTO 1031 is offset from the indicator 1015. The second cell time indicator 1042 may indicate a state where the second CTO 1032 is offset from the value of the FRC. That is, the second cell time indicator 1042 may indicate a position where the second CTO 1032 is offset from the indicator 1015. The terminal may determine the actual synchronization time based on the FRC value and the CTO value. The value obtained by adding the CTO value of the cell to the FRC value may represent the actual synchronization time of the corresponding cell.

[0175] The synchronization time condition can be used to determine whether the cell synchronization succeeds or fails. That is, the terminal can determine whether the cell synchronization succeeds or fails according to whether the cell time of the cell is within the expected synchronization range {ie, the valid range (eg, equation 2)}.

[0176] The valid range of the first carrier may be a first valid range 1051. The terminal may obtain synchronization of the first carrier from a synchronization signal of the first cell. The terminal may determine the cell time of the first carrier based on the first CTO 1031. The terminal may determine the cell time of the first carrier according to the value indicated by the first cell time indicator 1041. If the cell time K indicated by the first cell time indicator 1041 is 1 Within the first valid range 1051, the terminal can determine that the synchronization of the first cell is successful.

[0177] The valid range of the second carrier may be a second valid range 1052. The terminal may obtain synchronization of the second carrier from a synchronization signal of the second cell. The terminal may determine the cell time of the second carrier based on the second CTO 1032. The terminal may determine the cell time of the second carrier according to the value indicated by the second cell time indicator 1042. Because the cell time K indicated by the second cell time indicator 1042 is 2 It is not in the second valid range 1052, so the terminal can determine that the synchronization of the second cell has failed.

[0178] Since the synchronization of the second carrier fails, the terminal may need to restore the synchronization of the second carrier. The terminal may determine the synchronization of the unsynchronized second carrier based on the synchronization of the first carrier in synchronization.

[0179] In some embodiments, the first carrier and the second carrier may be sent to the terminal from the same base station, and the same beam may be used to serve the terminal through the first carrier and the second carrier. Therefore, the synchronization of the first carrier and the synchronization of the second carrier may be set to be equal or similar within a predetermined error range.

[0180] If the second carrier is not synchronized, the terminal may determine the synchronization of the first carrier as the synchronization of the second carrier. More specifically, the terminal may determine the first CTO 1031 as the compensated CTO 1062. The terminal may compensate for the synchronization of the second carrier according to the FRC value and the compensated CTO value. The terminal may move the second cell time indicator 1042 to point to a position offset from the indicator 1015 by the compensated CTO 1062. The terminal may determine that the cell time K indicated by the second cell time indicator 1024 is 2 The second carrier is within the second valid range 1052, so the synchronization of the second carrier has been restored. The terminal may determine that the synchronization of the second carrier is successful.

[0181] According to various embodiments, the terminal may include: Fig.10The FRC shown. In some embodiments, the terminal may include separate hardware in which the FRC is implemented. Each cell timer in the terminal may be operably connected to the FRC. Since the FRC is implemented as independent hardware, errors due to external factors can be reduced and accurate synchronization can be provided. In some other embodiments, the terminal may include a memory in which the FRC is implemented as software. Each cell timer in the terminal may be implemented as a reference memory.

[0182] The terminal may include a single FRC, and each cell timer may be synchronized by referring to the single FRC. Since the FRC is shared by each cell timer, the value of the FRC may be used as a reference for obtaining synchronization of each cell timer. At the same time, the present disclosure does not exclude the configuration that the terminal includes multiple FRCs and a single FRC. Each cell timer may be implemented as referring to some of the multiple FRCs. Even if multiple FRCs are implemented, the same FRC value may need to be provided to each cell timer in order to provide a reference value.

[0183] Fig.11A An example of synchronization compensation based on cell deployment according to an embodiment of the present disclosure is shown. The cell deployment may include a physical location of each cell, a coverage area, a frequency band of the cell, etc. In addition, the cell deployment may include a base station deployment.

[0184] Reference Fig.11A , the terminal 1120 may be served by the first base station 1101 through the first carrier 1121. The terminal 1120 may be served by the second base station 1102 through the second carrier 1122. The terminal 1120 may be served by the third base station 1103 through the third carrier 1123. The terminal 1120 may be served by the fourth base station 1104 through the fourth carrier 1124. The terminal 120 may perform CA including four carriers. Hereinafter, an example will be described in which the first base station 1101, the second base station 1102, and the third base station 1103 are separated from each other by a long distance and the third base station 1103 and the fourth base station 1104 are spatially adjacent to each other.

[0185] If the physical locations of the base stations are separated by a long distance from each other, there may be differences in the propagation paths between the synchronization signals sent from the base stations, so that the synchronization differences between the carriers of the adjacent frequency bands may increase. As described above, if the similarity between the synchronizations is not satisfied, it may be difficult to use the individual synchronization segments for synchronization compensation with each other. For example, even if the first carrier 1121 is in synchronization and the second carrier 1122 is not synchronized, the terminal 1120 may not compensate for the synchronization of the second carrier 1122 based on the synchronization of the first carrier 1121.

[0186] At the same time, if the positions of the base stations are the same or adjacent to each other, the propagation paths of the synchronization signals sent from the base stations may be similar even if the base stations are different. Therefore, the synchronization between the base stations may be similar. If the similarity between the synchronizations is met, the synchronization segments may be used for synchronization compensation with each other. For example, if the third carrier 1123 is in synchronization and the fourth carrier 1124 is not synchronized, the terminal 1120 may compensate for the synchronization of the fourth carrier 1124 based on the synchronization of the third carrier 1123. For example, the terminal may apply the cell time of the third carrier 1123 to the cell time of the fourth carrier 1124. As described above, in order to determine the synchronization of another carrier based on the synchronization of a specific carrier, the terminal needs to consider the cell deployment. In the following, when the similarity between the synchronizations is met, for the convenience of description, it will be represented as the cells being co-located with each other.

[0187] In some embodiments, the terminal may perform synchronization compensation based on TA. The terminal may calculate the degree of correspondence between the physical location of the terminal and each base station based on the TA value received from the base station. In the case of base stations whose difference between TA values ​​is less than a threshold range, the terminal may use mutually acquired synchronization for synchronization compensation. In addition, a timing advance group (TAG) may be used in a manner similar to a TA. For example, the terminal may use inter-cell synchronization to perform synchronization compensation on a cell provided from a base station in the same TAG. That is, the cells provided from the base station in the same TAG are co-located with each other.

[0188] In addition, in some embodiments, the terminal may perform synchronization compensation based on statistical information. Base stations adjacent to each other may have the same statistical characteristics. Statistical features may include propagation delay, Doppler shift, delay spread, the frequency of terminal access, and the frequency of use of beams. The terminal may determine base stations whose correlation between statistical characteristics is higher than a threshold as the same group, and may perform synchronization compensation using synchronization between base stations in the same group. That is, the cells provided by the base stations in the same group are co-located with each other.

[0189] In addition, in some embodiments, the terminal can perform synchronization compensation based on beam information. When a synchronization signal is received by means of the same terminal beam, the terminal can use the synchronization of the cell associated with the same terminal beam to perform synchronization compensation. When a synchronization signal is received from the beam of the same base station, the terminal can use the synchronization of the cell associated with the beam of the same base station to perform synchronization compensation. When the synchronization signal is received using the same beam pair, the terminal can use the synchronization of the cell associated with the same beam pair to perform synchronization compensation. On the other hand, in addition to the same beam or the same beam pair, the terminal can manage the beam group according to the direction of the beam, thereby performing synchronization compensation more effectively. The cells provided by the individual beams in the beam group are co-located with each other.

[0190] The terminal may include multiple RF paths to perform CA. The terminal may support CA on many carriers through multiple RF paths. In this case, due to hardware limitations, the beams used and the available frequency bands may be determined based on the RF. Fig. 11B An example of performing synchronization compensation based on an RF path is described.

[0191] Fig. 11B An example of synchronization compensation based on an RF path according to an embodiment of the present disclosure is shown. Each RF chain may form an independent radio path. The radio path may include an RF module and a modem. The terminal may include multiple radio frequency (RF) chains for CA. Due to the physical limitations of the filter, the terminal cannot flexibly support all frequency bands of CA through a single RF chain. Therefore, depending on the configuration of the filter, each RF chain may be configured to provide at least one specific carrier. According to various embodiments, the terminal may utilize information about the beam formed by each RF chain to obtain synchronization information for each carrier. In the following, the case where the first RF chain provides a first beam 1171, the second RF chain provides a second beam 1172, and the third RF chain provides a third beam 1173 will be described as an example.

[0192] refer to Fig. 11B , the terminal 1170 may perform communication with the first base station 1151. The first beam 1171 of the terminal may establish a wireless link with the first beam 1161 of the first base station 1151. The terminal 1170 may perform communication with the second base station 1152. The second beam 1172 of the terminal may establish a wireless link with the second beam 1162 of the second base station 1152. The terminal 1170 may perform communication with the third base station 1153. The third beam 1173 of the terminal may establish a wireless link with the third beam 1163 of the third base station 1153. The terminal may communicate with each of the three physically separated base stations through the three beams of the terminal. The first beam 1171, the second beam 1172, and the third beam 1173 of the terminal may be beams directed in various directions. These directions may be separated from each other in space. When the respective beams are spatially directed in spatially separated directions, the synchronization signals received through the respective beams are also received through different RF paths.

[0193] According to various embodiments, the terminal may perform synchronization compensation between carriers supported by a single RF chain. For example, in the case where a first RF chain can provide a first carrier and a second carrier, if the first carrier is not synchronized, the terminal may perform synchronization compensation using the synchronization of the second carrier to determine the synchronization of the first carrier.

[0194] According to various embodiments, the terminal may not recognize a carrier supported by another RF chain as a compensation carrier. That is, if the terminal recognizes a compensation carrier among carriers in synchronization, the terminal may not recognize a carrier different from an unsynchronized carrier provided by the RF chain as a compensation carrier.

[0195] As reference Fig. 11B As described above, the terminal can identify the compensation carrier used for synchronization compensation based on the beam information and synchronization information identified according to the physical hardware structure.

[0196] Fig.12 A flow chart of a terminal for determining whether CA synchronization is successful or failed according to an embodiment of the present disclosure is shown. The terminal may be Figure 1 The terminal 120 in.

[0197] Reference Fig.12 , the terminal may identify a carrier in operation 1201. The terminal may sequentially identify a carrier set for CA of the terminal.

[0198] In operation 1203, the terminal may determine whether synchronization of the carrier identified in operation 1201 succeeds or fails. The terminal may determine whether a channel quality condition of the identified carrier is satisfied. The channel quality condition may be intended to determine synchronization success or failure based on channel quality. The terminal may determine whether the channel quality of the carrier is higher than a predetermined reference. If the channel quality is higher than the predetermined reference, the terminal may determine that the condition is satisfied. For example, the terminal may determine whether the BLER of the PDSCH of the carrier is a quality threshold (R BLER2 ). The quality threshold can be set equal to or different from Fig. 8A If the BLER is equal to or greater than the quality threshold, the terminal may determine that the channel quality condition is met. If the channel quality condition is met, the terminal may perform operation 1205. If the channel quality condition is not met, the terminal may perform operation 1209.

[0199] In operation 1205, the terminal may determine whether synchronization success or failure has been determined for all carriers. That is, the terminal may determine whether the determination of whether the channel quality condition is satisfied in operation 1203 has been performed for all carriers. This is due to the fact that only when all carriers are in synchronization can the terminal send and receive data through CA without unnecessary decoding or processing delays. The terminal may determine whether the carrier for which the channel quality condition is determined in operation 1203 of the current cycle is the last carrier set for the terminal.

[0200] If synchronization success or failure has been determined for all carriers, the terminal may perform operation 1207. If synchronization success or failure has not been determined for all carriers, the terminal may re-perform operation 1201. The terminal may identify a carrier (e.g., a carrier with index m+1) after the carrier (e.g., a carrier with index m) identified in the previous cycle in operation 1201. The terminal may repeat operations 1201 to 1205 to determine synchronization success or failure for all carriers.

[0201] In operation 1207, the terminal may determine that CA synchronization is successful. The terminal may perform CA. In operation 1209, the terminal may determine that CA synchronization fails. The terminal cannot perform CA according to the currently configured carrier. The terminal may perform an additional process to restore synchronization of the unsynchronized carrier. For example, the terminal may perform an RRE process to reconnect to the base station.

[0202] Despite Fig.12 The channel quality condition is described by way of example in the above description, but the present disclosure is not limited thereto. The terminal may also use other conditions or additional conditions to determine whether CA synchronization is successful or failed. For example, the terminal may determine whether CA synchronization is successful or failed based on a synchronization time condition (i.e., whether the synchronization of each compensated carrier is within a predetermined range).

[0203] Fig.13 FIG. 1 shows a flow chart of a terminal for signal processing according to a success or failure of CA synchronization according to an embodiment of the present disclosure. The terminal may be Figure 1 The terminal 120 in. Fig.13 Shows Figure 7 or Fig.12 The process in the terminal after the process in.

[0204] Reference Fig.13 , the terminal may determine whether CA synchronization is successful or failed in operation 1301. The terminal may Fig.12 The terminal may determine whether CA synchronization is successful or failed as shown in FIG. If CA synchronization is successful, the terminal may perform operation 1303. If CA synchronization fails, the terminal may perform operation 1305.

[0205] In operation 1303, the terminal may process a baseband signal. The terminal may process baseband signals received from various cells constituting CA to perform CA. For example, the terminal may decode a Pcell signal and an Scell ​​signal respectively.

[0206] In operation 1305, the terminal may determine a radio link failure (RLF). The terminal may declare an RLF and may search for synchronization of the Pcell again. In addition, the terminal may perform an RRE. That is, the terminal may release all settings and resource allocations maintained during the connection, and may re-execute the initial connection process and the setting process related thereto. The terminal may also reset and reactivate the Scell. Although the present disclosure describes a synchronization recovery process for compensating for the synchronization of an unsynchronized carrier using the synchronization of a carrier in synchronization, a reconnection process (e.g., RRE) and synchronization recovery performed by the terminal after determining whether synchronization has been restored by performing synchronization compensation may also be understood as an embodiment.

[0207] although Fig.13 It is shown that if CA synchronization fails, the terminal declares RLF, and the terminal may not declare RLF immediately. In some embodiments, if the unsynchronized cell is a Scell, the terminal may determine whether to maintain CA or declare RLF based on the number of unsynchronized Scells. In some other embodiments, if the unsynchronized cell is a Scell, the terminal may add a carrier to the Scell, which is configured for CA but not activated for the Scell ​​after excluding the Scell. The terminal may use the synchronization information obtained during the inter-frequency measurement to add the Scell ​​for CA.

[0208] An example for obtaining and compensating for the synchronization of each carrier set for CA has been described in the present disclosure. However, the present disclosure is not limited to CA. All processes for recovering the synchronization of the frequency of an unsynchronized carrier using a synchronization signal sent via another carrier frequency may be understood as embodiments of the present disclosure. For example, in a dual connection case, the terminal may recover the synchronization of a specific carrier frequency (e.g., an NR cell) using the synchronization of another carrier frequency (e.g., an LTE cell).

[0209] According to various embodiments, when performing inter-frequency measurement, the terminal may perform the synchronization compensation of the present disclosure. For example, the terminal may 1 The first measurement is performed for the frequency band and for f 2 The second measurement is performed on the frequency band. Assuming f 1 Frequency band and f 2 The frequency bands are located in the same base station or are physically adjacent to each other, thereby satisfying synchronization similarity. In this case, if the synchronization for the first measurement fails, the terminal can 2The terminal may determine the synchronization of the first frequency band obtained in the first measurement based on the synchronization of the frequency band. As another example, even if communication is performed using a single carrier, the terminal may perform synchronization compensation based on the synchronization of each neighboring cell obtained by the inter-frequency measurement. As another example, the terminal may perform synchronization compensation on a carrier configured and activated for CA based on the synchronization of a carrier configured but not activated for CA.

[0210] Although the present disclosure describes the PSS or SSS in the cellular band as an example of a synchronization signal, all signals used to obtain synchronization can be understood as embodiments of the present disclosure. For example, if the Scell ​​operates in an unlicensed band for LAA support, the recovery signal can be used to obtain synchronization of the cell.

[0211] In the present disclosure, although the expression "equal to or greater than" or "equal to or less than" has been used to determine whether a specific condition is satisfied or achieved, this is only an example, and the expression "greater than" or "less than" is not excluded. Under the above conditions, the expression "equal to or greater than" may be replaced with "greater than", the expression "equal to or less than" may be replaced with "less than", and the expression "equal to or greater than and less than" may be replaced with "greater than, equal to, or less than".

[0212] The methods according to the embodiments described in the claims and / or the specification of the present disclosure may be implemented in hardware, software, or a combination of hardware and software.

[0213] When the method is implemented by software, a computer-readable storage medium for storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium may be configured to be executed by one or more processors in an electronic device. At least one program may include instructions that cause an electronic device to execute the method according to the various embodiments of the present disclosure defined by the attached claims and / or disclosed herein.

[0214] The program (software module or software) can be stored in a non-volatile memory, which includes random access memory and flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic disk storage device, compact disc-ROM (CD-ROM), digital versatile disc (DVD) or other type of optical storage device or cassette tape. Alternatively, any combination of some or all can form a memory for storing programs. In addition, multiple such memories can be included in the electronic device.

[0215] In addition, the program can be stored in an attachable storage device that can be accessed through a communication network such as the Internet, an intranet, a local area network (LAN), a wide area network (WAN), and a storage area network (SAN) or a combination thereof. Such a storage device can access the electronic device via an external port. In addition, a separate storage device on a communication network can access the portable electronic device.

[0216] In the above detailed embodiments of the present disclosure, the components included in the present disclosure are expressed in the singular or plural, depending on the detailed embodiments presented. However, for ease of description, the singular form or plural form is selected to be suitable for the presented situation, and the various embodiments of the present disclosure are not limited to its single element or its multiple elements. In addition, multiple elements expressed in the specification can be configured as a single element, or a single element in the specification can be configured as multiple elements.

[0217] While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A method for a terminal in a wireless communication system, the method comprising: monitoring synchronization of at least one cell; detecting asynchronism of the second cell; identifying at least one first cell in synchronization from the at least one cell; as well as Based on the at least one first synchronization information of the at least one first cell, second synchronization information of the second cell is obtained.

2. The method according to claim 1, further comprising: Communication is performed based on the second synchronization information.

3. The method according to claim 1, wherein: The detecting asynchronism of the second cell comprises: Identify at least one of the following: According to whether the maximum correlation value of the second cell of the synchronization sequence exceeds the correlation threshold, whether the cell time of the second cell is within a predetermined range, or Whether the channel quality of the second cell is equal to or greater than a threshold.

4. The method according to claim 1, wherein: The obtaining the second synchronization information of the second cell includes: identifying at least one cell time offset of the at least one first cell from the at least one first synchronization information; and A cell time offset of the second cell is determined based on the at least one cell time offset of the at least one first cell.

5. The method according to claim 1, wherein: The at least one first cell and the second cell are associated with a beam or a beam group.

6. The method according to claim 1, wherein: The at least one first cell and the second cell are associated with a timing advance group TAG.

7. The method according to claim 2, in, performing the communication includes changing a synchronization parameter of the second cell from previous second synchronization information to the second synchronization information, and When it is detected that the second cell is out of synchronization, the previous second synchronization information is used.

8. The method according to claim 2, wherein: Performing the communication based on the second synchronization information includes: determining whether the second cell is synchronized based on the second synchronization information; and If the second cell is in synchronization, the communication is performed using the at least one first cell and the second cell based on carrier aggregation CA without at least one of a radio link failure RLF or a radio reestablishment RRE of the second cell, and If the second cell is not synchronized, the communication is performed using the at least one first cell without the second cell.

9. The method according to claim 8, further comprising: If the second cell is not synchronized, performing RRE of the second cell.

10. The method according to claim 8, further comprising: If the second cell is not synchronized, the secondary cell SCell of the second cell is deleted.

11. A device for a terminal in a wireless communication system, the device comprising: at least one transceiver; as well as at least one processor configured to be operably connected to the at least one transceiver, Wherein, the at least one processor is further configured to: monitoring synchronization of at least one cell, Detecting asynchronism of the second cell, identifying at least one first cell in synchronization from the at least one cell, and Based on the at least one first synchronization information of the at least one first cell, second synchronization information of the second cell is obtained.

12. The device according to claim 11, wherein The at least one processor is further configured to: Communication is performed based on the second synchronization information.

13. The device according to claim 11, wherein: The at least one processor is configured to: Identify at least one of the following: According to whether the maximum correlation value of the second cell of the synchronization sequence exceeds the correlation threshold, whether the cell time of the second cell is within a predetermined range, or Whether the channel quality of the second cell is equal to or greater than a threshold.

14. The device according to claim 11, wherein: The at least one processor is configured to: identifying at least one cell time offset of the at least one first cell from the at least one first synchronization information; as well as A cell time offset of the second cell is determined based on the at least one cell time offset of the at least one first cell.

15. The device according to claim 11, wherein The at least one first cell and the second cell are associated with at least one of a beam, a beam group, or a timing advance group TAG.

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