Method and apparatus for transmitting and receiving based on inter-carrier handover

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. In particular, the disclosure provides a method and apparatus for maximizing the utilization of a low frequency band frequency by causing a terminal to alternately receive a plurality of downlink carriers when performing low-band carrier aggregation in a next-generation wireless communication system.

Description

Technical Field

[0001] This disclosure relates to the operation of user equipment (UE) and base stations in wireless (or mobile) communication systems. Specifically, this disclosure relates not only to a UE capability configuration method based on UE architecture, enabling the UE to receive one carrier at a time when receiving a combination of multiple frequency bands or a combination of multiple carriers within a frequency band in a wireless communication system, with a time difference between the carriers, but also to a base station method that receives a report of corresponding UE capabilities and configures the downlink according to the UE capabilities when sending carrier aggregation of the corresponding combination to the UE; a method for configuring the time and time period for performing such variable handover operations; and apparatus for performing the same operations. Background Technology

[0002] 5G mobile communication technology defines a wide frequency band, enabling high transmission rates and new services. It can be implemented not only in the "below 6 GHz" band, such as 3.5 GHz, but also in the "above 6 GHz" band, including 28 GHz and 39 GHz, known as mmWave. Furthermore, 6G mobile communication technology (called Super 5G systems) has been considered for implementation in terahertz bands (e.g., the 95 GHz to 3 THz band) to achieve transmission rates fifty times faster than 5G and ultra-low latency one-tenth that of 5G.

[0003] At the outset of 5G mobile communication technology development, standardization was underway regarding beamforming and massive MIMO to support services and meet performance requirements associated with enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC). This standardization aimed to mitigate radio wave path loss in millimeter waves and increase radio wave transmission distance; support parameter sets for dynamic operation (e.g., operating multiple subcarrier spacings) to efficiently utilize millimeter wave resources and time slot formats; initial access technologies to support multi-beam transmission and broadband; the definition and operation of bandwidth portions (BWP); new channel decoding methods (such as low-density parity-check (LDPC) codes for large data transmissions and polar codes for highly reliable transmission of control information); L2 preprocessing; and network slicing for providing dedicated networks for specific services.

[0004] Currently, given the services supported by 5G mobile communication technology, discussions are underway regarding improvements and performance enhancements to the initial 5G mobile communication technology. Physical layer standardization for technologies such as Vehicle-to-Everything (V2X) is also in place, designed to assist autonomous vehicle driving decisions based on information about the vehicle's location and status transmitted by the vehicle, and to enhance user convenience. This includes NR-U (New Radio Unlicensed) and NR UE Energy Saving (NTN), which are UE-satellite direct communication technologies used to provide coverage and positioning in areas where communication with terrestrial networks is unavailable.

[0005] Furthermore, standardization is ongoing for technologies within the air interface architecture / protocol, such as the Industrial Internet of Things (IIoT) for supporting new services through interoperability and convergence with other industries, Integrated Access and Backhaul (IAB) for providing nodes for network service area extension by supporting wireless backhaul and access links in an integrated manner, mobility enhancements including conditional handover and Dual Active Protocol Stack (DAPS) handover, and two-step random access (two-step RACH for NR) for simplifying the random access process. Standardization is also underway for 5G baseline architectures (e.g., service-based architectures or service-based interfaces) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, as well as system architectures / services for Mobile Edge Computing (MEC) based on UE location reception services.

[0006] With the commercialization of 5G mobile communication systems, the already exponentially growing number of connected devices will be connected to the communication network, thus necessitating enhanced functionality and performance of 5G mobile communication systems as well as integrated operation of connected devices. To this end, new research related to extended reality (XR) has been arranged to effectively support augmented reality (AR), virtual reality (VR), mixed reality (MR), etc., by leveraging artificial intelligence (AI) and machine learning (ML), AI service support, metaspace service support, and drone communication to improve 5G performance and reduce complexity.

[0007] Furthermore, this development of 5G mobile communication systems will not only serve as the foundation for developing new waveforms for providing terahertz band coverage in 6G mobile communication technologies, such as multi-antenna transmission technologies like full-dimensional MIMO (FD-MIMO), array antennas, and massive MIMO; metamaterial-based lenses and antennas for improving terahertz band signal coverage; high-dimensional spatial multiplexing technologies using orbital angular momentum (OAM); and reconfigurable smart surfaces (RIS); it will also serve as the foundation for developing full-duplex technologies to improve the frequency efficiency of 6G mobile communication technologies and enhance system networks; AI-based communication technologies to achieve system optimization by leveraging satellites and AI from the design phase and internalizing end-to-end AI support functions; and next-generation distributed computing technologies to achieve services with complexity levels exceeding the operational capabilities of UEs by utilizing ultra-high-performance communication and computing resources.

[0008] Meanwhile, with the advancement of communication systems and the development of terminal receivers, research is being conducted on the process of receiving and processing multiple carriers configured and transmitted through non-contiguous carrier aggregation within a frequency band by a single terminal receiver, and on the configuration methods of frequency band parameters and frequency combination parameters of terminals used to support this process. Summary of the Invention

[0009] Technical issues

[0010] Various embodiments of this disclosure are intended to provide apparatus and methods capable of effectively providing services in mobile communication systems. In wireless communication systems, there are no particular limitations on the frequency band combinations configured for carrier aggregation-based transmission / reception. However, from the perspective of implementing a product that actually supports carrier aggregation, depending on signal distortion caused by the propagation characteristics of the frequency bands or carriers included in the combination, interference between multiple carriers, or the design of the UE supporting transmission / reception on multiple carriers, there is a possibility that transmission / reception using carrier aggregation may be unavailable, or that the performance of transmission / reception using carrier aggregation may be worse than transmission / reception using a single carrier. If carrier aggregation is actually unavailable or performs poorly (e.g., this is observed in combinations of low frequencies at or below 1 GHz, which have large diffraction characteristics and therefore good coverage, but poor line-of-sight characteristics, and are therefore disadvantageous in terms of interference control), it is not easily addressed in current UE design approaches that require supporting most frequency bands with limited components and resources. Therefore, various embodiments of this disclosure aim to provide a UE capability configuration method based on UE architecture, enabling the UE to receive specific carrier aggregations with time differences between carriers. Furthermore, various embodiments of this disclosure are intended to provide a method for configuring the time and time period for performing variable handover operations, as well as a detailed method for a base station to configure carrier aggregation transmission in the same manner.

[0011] The technical subject matter pursued by the various embodiments of this disclosure is not limited to the technical subject matter described above, and those skilled in the art may consider other technical subject matters not mentioned herein from the various embodiments of this disclosure described below.

[0012] Technical solution

[0013] Embodiments of this disclosure for addressing the aforementioned problems provide a method performed by a user equipment (UE) in a wireless communication system. The method includes: receiving a UE capability query message from a base station; and, in response to receiving the UE capability query message, sending a UE capability information message to the base station. The UE capability information message includes first information indicating support for low-band-low-band (LB-LB) carrier aggregation (CA) based on handover between a first low-frequency band (LB) supporting frequency division duplex (FDD) and a second LB supporting supplemental downlink (SDL). Based on the first information, during a first time period in which transmission or reception is performed in the FDD band of the first LB, reception is not performed in the SDL band of the second LB, and during a second time period in which reception is performed in the SDL band of the second LB, transmission or reception is not performed in the FDD band of the first LB.

[0014] Furthermore, embodiments of this disclosure provide a method performed by a base station in a wireless communication system. The method includes: sending a UE capability query message to a UE; and receiving a UE capability information message from the UE in response to sending the UE capability query message. The UE capability information message includes first information indicating support for low-band-low-band (LB-LB) carrier aggregation (CA) based on handover between a first low-frequency band (LB) supporting frequency division duplex (FDD) and a second LB supporting supplemental downlink (SDL). Based on the first information, during a first time period in which transmission or reception is performed in the FDD band of the first LB, reception is not performed in the SDL band of the second LB, and during a second time period in which reception is performed in the SDL band of the second LB, transmission or reception is not performed in the FDD band of the first LB.

[0015] Furthermore, embodiments of this disclosure provide a UE in a wireless communication system. The UE includes a memory storing instructions and processing circuitry connected to the memory, and the processing circuitry is configured to, at least in part, cause the UE to perform the following actions based on the execution of the instructions: receiving a UE capability query message from a base station; and, in response to receiving the UE capability query message, sending a UE capability information message to the base station, the UE capability information message including first information indicating support for low-band-low-band (LB-LB) carrier aggregation (CA) based on handover between a first LB supporting frequency division duplex (FDD) and a second LB supporting supplemental downlink (SDL), wherein, based on the first information, during a first time period in which transmission or reception is performed in the FDD band of the first LB, reception is not performed in the SDL band of the second LB, and during a second time period in which reception is performed in the SDL band of the second LB, transmission or reception is not performed in the FDD band of the first LB.

[0016] Furthermore, embodiments of this disclosure provide a base station in a wireless communication system. The base station includes a memory storing instructions and processing circuitry connected to the memory, and the processing circuitry is configured to, at least in part based on the execution of the instructions, cause the base station to: send a UE capability query message to a user equipment (UE); and, in response to sending the UE capability query message, receive a UE capability information message from the UE, the UE capability information message including first information indicating support for low-band-low-band (LB-LB) carrier aggregation (CA) based on handover between a first LB supporting frequency division duplex (FDD) and a second LB supporting supplemental downlink (SDL), wherein, based on the first information, during a first time period in which transmission or reception is performed in the FDD band of the first LB, reception is not performed in the SDL band of the second LB, and during a second time period in which reception is performed in the SDL band of the second LB, transmission or reception is not performed in the FDD band of the first LB.

[0017] The various embodiments of this disclosure described above are merely some preferred embodiments of this disclosure, and those skilled in the art can deduce and understand various embodiments reflecting the technical features of various embodiments of this disclosure based on the detailed description that will be described in detail below.

[0018] Beneficial effects

[0019] Various embodiments of this disclosure can provide apparatus and methods for effectively providing services in mobile communication systems.

[0020] According to various embodiments of the present disclosure, a method for performing carrier aggregation in a wireless communication system, in which a base station and a user equipment (UE) fully utilize available frequency bands and maximize frequency efficiency without considering frequency band combinations, and an apparatus for performing the same method, may be provided.

[0021] The beneficial effects that can be obtained from the various embodiments of this disclosure are not limited to the effects described above, and those skilled in the art can clearly deduce and understand other effects not mentioned herein based on the following description. Attached Figure Description

[0022] Figure 1 The basic structure of the time-frequency domain in a wireless communication system according to an embodiment of the present disclosure is shown.

[0023] Figure 2 The structure of frames, subframes, and time slots in a wireless communication system according to embodiments of the present disclosure is shown.

[0024] Figure 3 An example of bandwidth configuration in a wireless communication system according to an embodiment of the present disclosure is shown.

[0025] Figure 4 An example of base station beam allocation configured according to a Transmission Configuration Indication (TCI) state in a wireless communication system according to an embodiment of the present disclosure is shown.

[0026] Figure 5 The wireless protocol structures of a base station and a UE in a wireless communication system according to embodiments of the present disclosure are shown in single-cell, carrier aggregation, and dual connectivity scenarios.

[0027] Figure 6 Examples of duplexers and in-band interference in low-frequency carrier transmission and reception are shown.

[0028] Figure 7 Examples of duplexers, dual-frequency converters, and inter-band interference in multi-low frequency carrier transmission and reception are shown.

[0029] Figure 8 An example is shown of a base station and a UE performing transmission and reception based on inter-carrier handover in carrier aggregation.

[0030] Figure 9 An example is shown of a base station and a UE performing transmission and reception based on inter-carrier handover in carrier aggregation.

[0031] Figure 10 An example is shown of a base station and a UE performing transmission and reception based on inter-carrier handover in carrier aggregation.

[0032] Figure 11 An example is shown where the base station and UE perform inter-carrier handover-based transmission and reception based on the UE's capability report.

[0033] Figure 12 An example is shown of the period during which the base station does not perform downlink transmission or the maximum period required for the UE to change the receiver in carrier aggregation based on downlink handover.

[0034] Figure 13 The structure of a UE in a wireless communication system according to an embodiment of the present disclosure is shown.

[0035] Figure 14 The structure of a base station in a wireless communication system according to an embodiment of the present disclosure is shown. Detailed Implementation

[0036] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0037] In describing the embodiments, descriptions of technical content known in the relevant art and not directly related to this disclosure will be omitted. This omission of unnecessary description is intended to prevent obscuring the main concepts of this disclosure and to more clearly convey those main concepts.

[0038] For the same reason, some elements may be exaggerated, omitted, or shown schematically in the accompanying drawings. Furthermore, the dimensions of individual parts do not perfectly reflect their actual dimensions. The same or corresponding parts in each drawing are indicated by the same reference numerals.

[0039] The advantages and features of this disclosure, as well as the ways in which these advantages and features are realized, will become apparent from the following detailed description of embodiments in conjunction with the accompanying drawings. However, this disclosure is not limited to the embodiments set forth below, but can be implemented in various different forms. The following embodiments are provided only to fully disclose this disclosure and to inform those skilled in the art of its scope, and this disclosure is limited only by the scope of the appended claims. Throughout the specification, the same or similar reference numerals denote the same or similar elements. Furthermore, in describing this disclosure, detailed descriptions of known functions or configurations contained herein will be omitted where it is determined that such detailed descriptions would unnecessarily obscure the subject matter of the disclosure. Additionally, the terminology described below is defined in consideration of the functions in this disclosure and may vary depending on the user, the user's intent, or convention. Therefore, it should be defined based on the entire content of this specification.

[0040] In this document, it should be understood that each box in a flowchart, and combinations of boxes in a flowchart, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more boxes of the flowchart. These computer program instructions can also be stored in a computer-usable or computer-readable storage medium capable of directing the computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-usable or computer-readable storage medium produce an article of writing including instruction means for implementing the functions specified in one or more boxes of the flowchart. Computer program instructions that execute on a computer or other programmable data processing apparatus and cause a series of operational steps to be performed on the computer or other programmable data processing apparatus to produce a computer-implemented process can provide steps for implementing the functions specified in one or more boxes of the flowchart.

[0041] Furthermore, each box in a flowchart can represent a module, segment, or section of code, which includes one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the boxes may not occur in the order shown. For example, two boxes shown consecutively may actually execute substantially simultaneously, or these boxes may sometimes execute in reverse order depending on the functions involved.

[0042] As used in the embodiments of this disclosure, the term "unit" refers to a software element or hardware element, such as a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC), and a "unit" performs certain functions. However, the meaning of "unit" is not always limited to software or hardware. A "unit" can be configured to be stored in an addressable storage medium or to execute one or more processors. Thus, a "unit" includes, for example, software elements, object-oriented software elements, class elements or task elements, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and parameters. The elements and functions provided by a "unit" can be combined into a smaller number of elements or "units," or divided into a larger number of elements or "units." Furthermore, the elements and "units" can be implemented to reproduce one or more CPUs within a device or secure multimedia card. Additionally, a "unit" in the embodiments may include one or more processors.

[0043] Wireless communication systems are evolving into broadband wireless communication systems, which, in addition to typical voice-based services, use communication standards such as 3GPP High-Speed ​​Packet Access (HSPA), LTE (Long Term Evolution or Evolved Universal Terrestrial Radio Access (E-UTRA)), Advanced LTE (LTE-A), LTE-Pro, 3GPP2 High-Rate Packet Data (HRPD), Ultra Mobile Broadband (UMB), and IEEE 802.16e to provide high-speed and high-quality packet data services.

[0044] As a typical example of a broadband wireless communication system, the LTE system employs Orthogonal Frequency Division Multiplexing (OFDM) in the downlink (DL) and Single-Carrier Frequency Division Multiple Access (SC-FDMA) in the uplink (UL). The uplink refers to the radio link through which a User Equipment (UE) or Mobile Station (MS) transmits data or control signals to a Base Station (BS) (or eNode B), while the downlink refers to the radio link through which the Base Station transmits data or control signals to the UE. These multiple access schemes separate the data or control information of each user by allocating and manipulating the time-frequency resources used to transmit each user's data or control information, thus avoiding overlap and establishing orthogonality.

[0045] As a post-LTE communication system, 5G communication systems must flexibly respond to the various requirements of users, service providers, and others, and therefore must support services that meet diverse needs. Services considered in 5G communication systems include enhanced mobile broadband (eMBB) communication, massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC).

[0046] eMBB aims to provide data rates higher than those supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, for a single base station, eMBB must provide a peak data rate of 20Gbps in the downlink and 10Gbps in the uplink. Furthermore, 5G communication systems must provide the UE with increased user-perceived data rates and maximum data rates. To meet these requirements, improved transmit / receive technologies, including further enhanced multiple-input multiple-output (MIMO) transmission, are needed. Moreover, the data rates required by 5G communication systems can be achieved by using a bandwidth greater than 20MHz in the 3-6GHz or higher frequency bands, rather than using a maximum transmit bandwidth of 20MHz in the 2GHz band as in LTE.

[0047] Furthermore, mMTC is being considered in 5G communication systems to support application services such as the Internet of Things (IoT). To effectively deliver IoT, mMTC has requirements such as supporting a large number of UEs within a cell, enhancing UE coverage, improving battery life, and reducing UE costs. Since IoT provides communication capabilities when supplied to various sensors and devices, it must support a large number of UEs within a cell (e.g., 1,000,000 UEs / km). 2 Furthermore, due to the nature of the service, mMTC-enabled UEs may be located in shadowed areas not covered by cell coverage, such as building basements, and therefore may require wider coverage than UEs providing other services offered by 5G communication systems. mMTC-enabled UEs must be configured to be inexpensive, and due to the difficulty in frequently replacing UE batteries, they may require very long battery lifespans, such as 10 to 15 years.

[0048] Finally, URLLC is a cellular-based mission-critical wireless communication service. For example, URLLC can be used for services such as remote control of robots or machines, industrial automation, unmanned aerial vehicles, remote healthcare, and emergency alerts. Therefore, URLLC must provide communication with ultra-low latency and ultra-high reliability. For example, services supporting URLLC must meet an air interface latency of less than 0.5 ms and may also require 10 -5 Or even lower packet error rates. Therefore, for services supporting URLLC, 5G systems must provide shorter Transmission Time Intervals (TTIs) than other services, and may also require designs that allocate significant resources in frequency bands to ensure the reliability of communication links.

[0049] The three services in 5G—eMBB, URLLC, and mMTC—can be multiplexed and transmitted within a single system. In this case, different transmit / receive technologies and parameters can be used between services to meet their varying requirements. Of course, 5G is not limited to these three services.

[0050] As used herein, a base station is an entity that allocates resources to a terminal and can be at least one of a gNode B, eNode B, Node B, base station (BS), radio access unit, base station controller, and nodes on a network. A terminal can include a user equipment (UE), mobile station (MS), cellular phone, smartphone, computer, or multimedia system capable of performing communication functions. As used herein, "downlink (DL)" refers to a radio link through which a base station transmits signals to a terminal, and "uplink (UL)" refers to a radio link through which a terminal transmits signals to a base station. Furthermore, while LTE or LTE-A systems are described by example in the following description, embodiments of this disclosure can also be applied to other communication systems with similar technical backgrounds or channel types. Examples of such communication systems may include fifth-generation mobile communication technologies (5G, New Radio, or NR) developed after LTE-A, and in the following description, "5G" can be a concept encompassing existing LTE, LTE-A, and other similar services. Moreover, based on the judgment of those skilled in the art, this disclosure can also be applied to other communication systems with modifications without significantly departing from the scope of this disclosure.

[0051] In the following description, the term “a / b” can be understood as at least one of “a” and “b”.

[0052] [NR Time and Frequency Resources]

[0053] The frame structure of the 5G system will be described in more detail below with reference to the accompanying drawings.

[0054] Figure 1 The basic structure of the time-frequency domain in a 5G system is shown. The time-frequency domain is a radio resource domain used for transmitting data or control channels.

[0055] exist Figure 1 In the diagram, the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. The basic unit of resources in both the time and frequency domains is a resource element (RE) 101, which can be defined as an orthogonal frequency division multiplexing (OFDM) symbol 102 along the time axis and a subcarrier 103 along the frequency axis. In the frequency domain, (For example, 12) consecutive REs can constitute a resource block (RB) 104. In the time domain, a subframe 110 can include multiple OFDM symbols 102. For example, the length of a subframe can be 1 ms.

[0056] Figure 2 The structure of frames, subframes, and time slots in a wireless communication system according to embodiments of the present disclosure is shown.

[0057] Figure 2An example of the structure of frame 200, subframe 201, and time slot 202 is shown. A frame 200 can be defined as 10 ms. A subframe 201 can be defined as 1 ms, therefore a frame 200 can include a total of ten subframes 201. A time slot 202 or 203 can be defined as 14 OFDM symbols (i.e., the number of symbols per time slot). =14). A subframe 201 may include one or more time slots 202 and 203, and the number of time slots 202 and 203 in each subframe 201 may vary depending on the configuration value μ of the subcarrier spacing 204 or 205. Figure 2 The examples illustrate the cases where the subcarrier spacing configuration value is μ=0 (204) and μ=1 (205). In the case of μ=0 (204), a subframe 201 may include one time slot 202, and in the case of μ=1 (205), a subframe 201 may include two time slots 203. That is, the number of time slots per subframe... The number of time slots per frame can vary depending on the subcarrier spacing configuration value μ. They can differ accordingly. As shown in Table 1 below, and It can be defined based on the configuration μ for each subcarrier spacing.

[0058] [Table 1]

[0059]

[0060] [Bandwidth Component (BWP)]

[0061] Next, the bandwidth portion (BWP) configuration in a 5G communication system will be described in detail with reference to the accompanying drawings.

[0062] Figure 3 An example of bandwidth configuration in a wireless communication system according to an embodiment of the present disclosure is shown.

[0063] Figure 3 An example is shown where the UE bandwidth 300 is configured to include two bandwidth portions, namely bandwidth portion #1 (BWP#1) 301 and bandwidth portion #2 (BWP#2) 302. The base station can configure one or more bandwidth portions for the UE, and can configure the information given below for each bandwidth portion.

[0064] [Table 2]

[0065]

[0066] Of course, the above examples are not limiting, and various parameters related to the bandwidth portion can be configured for the UE in addition to the configuration information given above. The base station can transmit configuration information to the UE via higher-layer signaling (e.g., Radio Resource Control (RRC) signaling). At least one of the configured bandwidth portions can be activated. Whether the configured bandwidth portion is activated can be semi-statically transmitted from the base station to the UE via RRC signaling or dynamically transmitted via downlink control information (DCI).

[0067] According to some embodiments, prior to Radio Resource Control (RRC) connection, the base station can configure an Initial Bandwidth Part (BWP) for initial access for the UE via the Master Information Block (MIB). More specifically, the UE can receive configuration information regarding the Control Resource Set (CORESET) and the search space, which can be used to transmit the Physical Downlink Control Channel (PDCCH) to receive system information necessary for initial access via the MIB during the initial access step (which may correspond to the Residual System Information (RMSI) or System Information Block 1 (SIB1)). Each of the Control Resource Set and the search space configured via the MIB can be considered to have an ID of 0. The base station can notify the UE via the MIB of configuration information regarding the Control Resource Set #0, such as frequency allocation information, time allocation information, and parameter set. Furthermore, the base station can notify the UE via the MIB of configuration information regarding the monitoring period and timing of the Control Resource Set #0, i.e., configuration information regarding the search space #0. The UE can consider the frequency domain configured by the Control Resource Set #0 obtained from the MIB as the Initial Bandwidth Part for initial access. The ID of the Initial Bandwidth Part can be considered to be 0.

[0068] 5G-supported bandwidth-related configurations can be used for a variety of purposes.

[0069] According to some embodiments, if the bandwidth supported by the UE is less than the system bandwidth, this can be supported through bandwidth portion configuration. For example, the base station can configure the frequency position of the bandwidth portion for the UE, so that the UE can send / receive data at a specific frequency position within the system bandwidth.

[0070] Furthermore, according to some embodiments, to support different parameter sets, the base station can configure multiple bandwidth portions for the UE. For example, to support data transmission / reception using both 15kHz and 30kHz subcarrier intervals, the two bandwidth portions can be configured with 15kHz and 30kHz subcarrier intervals, respectively. Different bandwidth portions can employ frequency division multiplexing (FDM), and if data is to be transmitted / received at a specific subcarrier interval, the bandwidth portion configured for that subcarrier interval can be activated.

[0071] Furthermore, according to some embodiments, to reduce the power consumption of the UE, the base station can configure bandwidth portions with different bandwidth sizes for the UE. For example, if the UE supports a fairly large bandwidth (e.g., 100MHz) and always transmits / receives data at that bandwidth, it may result in considerable power consumption. In particular, from a power consumption perspective, unnecessarily monitoring the downlink control channel at a large bandwidth of 100MHz in the absence of traffic may be quite inefficient. To reduce the UE's power consumption, the base station can configure the UE with a bandwidth portion with a relatively small bandwidth (e.g., a 20MHz bandwidth portion). In the absence of traffic, the UE can perform monitoring operations in the 20MHz bandwidth portion, and if data is generated, it can transmit / receive data using the 100MHz bandwidth portion as instructed by the base station.

[0072] Regarding the bandwidth configuration method, the UE can receive configuration information about the initial bandwidth portion via the MIB during the initial access step before being connected via RRC. More specifically, the control resource set (i.e., CORESET) for the downlink control channel can be configured for the UE from the MIB of the physical broadcast channel (PBCH). This downlink control channel can be used to transmit downlink control information (DCI) for scheduling system information blocks (SIBs). The bandwidth of the control resource set configured by the MIB can be considered as the initial bandwidth portion, and the UE can receive the physical downlink shared channel (PDSCH) for transmitting SIBs through the configured initial bandwidth portion. In addition to receiving SIBs, the initial bandwidth portion can also be used for other system information (OSI), paging, and random access.

[0073] [Bandwidth Component (BWP) Change]

[0074] If one or more bandwidth portions have already been configured for the UE, the base station can use the bandwidth portion indicator field within the DCI to indicate to the UE a change (or switch or transition) in the bandwidth portion. As an example, if... Figure 3 If the currently active bandwidth portion of the UE is bandwidth portion #1 301, the base station can indicate bandwidth portion #2 302 through the bandwidth portion indicator in the DCI, and the UE can change the bandwidth portion to the bandwidth portion #2 302 indicated by the bandwidth portion indicator in the received DCI.

[0075] As mentioned above, DCI-based bandwidth portion changes can be indicated using the DCI used to schedule PDSCH or Physical Uplink Shared Channel (PUSCH). Therefore, upon receiving a bandwidth portion change request, the UE needs to be able to receive or transmit PDSCH or PUSCH scheduled by the corresponding DCI without problems within the changed bandwidth portion. To this end, the standard specifies the required delay time (T) during the bandwidth portion change.BWP The requirements are defined, for example, as shown in Table 3 below.

[0076] [Table 3]

[0077]

[0078] The bandwidth portion of the delay time requirement depends on the UE's capability to support either Type 1 or Type 2. The UE can report the supported bandwidth portion delay time type to the base station.

[0079] If the UE has already received the DCI including the bandwidth partial change indicator in time slot n, then according to the bandwidth partial change delay time requirement, the UE can proceed no later than time slot n+T. BWP The change of bandwidth portion is completed at the point in time indicated by the bandwidth portion change indicator, and the UE can transmit and / or receive data channels scheduled by the corresponding DCI in the new bandwidth portion. If the base station wants to use the new bandwidth portion to schedule data channels, the base station can consider the UE's bandwidth portion change delay time (T). BWP This method determines the temporal resource allocation for the data channel. Specifically, when scheduling a data channel using a new bandwidth portion, by combining this method with the method for determining the temporal resource allocation for the data channel, the base station can schedule the corresponding data channel after the bandwidth portion change delay time. Therefore, the UE can expect the DCI indicating the bandwidth portion change to indicate a delay time less than the bandwidth portion change delay time (T). BWP The time slot offset (K0 or K2) value.

[0080] If the UE has already received a DCI indicating a partial bandwidth change (e.g., DCI format 1_1 or 0_1), the UE may refrain from transmitting or receiving for a period from the third symbol of the time slot used to receive the PDCCH including the corresponding DCI to the start point of the time slot indicated by the time slot offset (K0 or K2) value indicated by the time domain resource allocation indicator field in the corresponding DCI. For example, if the UE has already received a DCI indicating a partial bandwidth change in time slot n, and if the time slot offset value indicated by the corresponding DCI is K, the UE may refrain from transmitting or receiving from the third symbol of time slot n to the symbols preceding time slot n+K (e.g., the last symbol of time slot n+K-1).

[0081] [Quasi-co-addressable (QCL), TCI state]

[0082] In wireless communication systems, one or more distinct antenna ports (which may be replaced by one or more channels, signals, or combinations thereof, but for ease of description, will be collectively referred to as distinct antenna ports in the following description of this disclosure) can be associated with each other through a quasi-co-location (QCL) configuration as shown in Table 4 below. The TCI state is used to announce the QCL relationship between the PDCCH (or PDCCH demodulation reference signal (DMRS)) and another reference signal (RS) or channel, and the description of the QCL between reference antenna port A (reference RS #A) and another target antenna port B (target RS #B) implies that the UE is allowed to apply some or all of the large-scale channel parameters estimated in antenna port A to channel measurements from antenna port B. The QCL needs to be associated with different parameters depending on conditions such as: 1) time tracking affected by average delay and delay spread; 2) frequency tracking affected by Doppler shift and Doppler spread; 3) radio resource management (RRM) affected by average gain; or 4) beam management (BM) affected by spatial parameters. Therefore, four QCL relationships are supported in NR as shown in Table 3 below.

[0083] [Table 4]

[0084]

[0085] Spatial reception parameters can refer to some or all of various parameters, such as angle of arrival (AoA), power angle spectrum (PAS) of AoA, angle of departure (AoD), PAS of AoD, transmit / receive channel correlation, transmit / receive beamforming, and spatial channel correlation.

[0086] QCL relationships can be configured for the UE using the RRC parameters TCI-state and QCL-info as shown in Table 5 below. Referring to Table 5, the base station can configure one or more TCI states for the UE, thereby informing up to two QCL relationships (qcl-Type1, qcl-Type2) regarding the RS (i.e., the target RS) with the ID of the reference TCI state. Each QCL information (QCL-Info) included in each TCI state includes the serving cell index and BWP index of the reference RS indicated by the corresponding QCL information, the type and ID of the reference RS, and the QCL type as shown in Table 4 above.

[0087] [Table 5]

[0088]

[0089] Figure 4 An example of base station beam allocation configured according to TCI status is shown.

[0090] Reference Figure 4The base station can transmit information about N different beams to the UE through N different TCI states. For example, in... Figure 4 As shown in the case of N=3, the base station can configure the qcl-Type2 parameter included in the three TCI states 400, 405 and 410 as QCL type D, and associate the parameter with the Channel State Information-Reference Signal (CSI-RS) or Synchronization Signal Block corresponding to different beams, thereby notifying the antenna ports referencing different TCI states 400, 405 and 410 to be associated with different spatial reception parameters (i.e. different beams).

[0091] Tables 6 through 10 below list the valid TCI state configurations based on the target antenna port type.

[0092] Table 6 lists the valid TCI state configurations when the target antenna port is a CSI-RS (i.e., TRS) used for tracking. In CSI-RS, TRS refers to a non-zero power (NZP) CSI-RS with no repetition parameter configured and its trs-Info configured as "true". In Table 10, configuration number 3 can be used for aperiodic TRS. (Table 6: Valid TCI state configurations when the target antenna port is a CSI-RS (TRS) used for tracking.)

[0093] [Table 6]

[0094]

[0095] Table 7 lists the valid TCI state configurations when the target antenna port is a CSI-RS for CSI. In CSI-RS, a CSI-RS for CSI refers to an NZP CSI-RS where no parameter indicating repetition is configured (e.g., repetition parameter) and its trs-Info is not configured to "true". (Table 7: Valid TCI state configurations when the target antenna port is a CSI-RS for CSI.)

[0096] [Table 7]

[0097]

[0098] Table 8 lists the valid TCI state configurations when the target antenna port is a CSI-RS for beam management (BM), which has the same meaning as the CSI-RS for physical layer (L1) reference signal received power (RSRP) reporting. In CSI-RS, the CSI-RS for BM refers to an NZP CSI-RS configured with a repeating parameter value of "on" or "off" and whose trs-Info is not configured as "true". (Table 8: Valid TCI state configurations when the target antenna port is a CSI-RS for BM (for L1 RSRP reporting).)

[0099] [Table 8]

[0100]

[0101] Table 9 lists the valid TCI state configurations when the target antenna port is a PDCCH DMRS. (Table 9: Valid TCI state configurations when the target antenna port is a PDCCH DMRS.)

[0102] [Table 9]

[0103]

[0104] Table 10 lists the valid TCI state configurations when the target antenna port is a PDSCH DMRS. (Table 10: Valid TCI state configurations when the target antenna port is a PDSCH DMRS.)

[0105] [Table 10]

[0106]

[0107] Based on the representative QCL configuration methods in Tables 6 to 10 above, the target antenna port and reference antenna port for each step are configured and operated as follows: "SSB" -> "TRS" -> "CSI-RS for CSI, or CSI-RS for BM, or PDCCH DMRS, or PDSCH DMRS". Therefore, by associating the statistical characteristics that can be measured from SSB and TRS with the individual antenna ports, the UE's reception operation can be aided.

[0108] [About CA / Dual Connection (DC)]

[0109] Figure 5 The radio protocol structures of the base station and UE in single-cell, carrier aggregation, and dual connectivity scenarios are illustrated according to embodiments of the present disclosure.

[0110] Reference Figure 5 The next-generation mobile communication system’s radio protocols on the UE side and the NR base station side each include NR Service Data Adaptation Protocol (SDAP) S25 or S70, NR Packet Data Convergence Protocol (PDCP) S30 or S65, NR Radio Link Control (RLC) S35 or S60, and NR Media Access Control (MAC) S40 or S55.

[0111] The main functions of NR SDAP S25 or S70 may include some of the following functions.

[0112] - Transmission of user plane data

[0113] - Mapping between DL and UL Quality of Service (QoS) streams and Data Radio Bearer (DRB)

[0114] - Mark QoS flow IDs in DL and UL groups

[0115] - Reflected QoS stream to DRB mapping for UL SDAP protocol data units (PDUs)

[0116] Regarding SDAP layer devices, RRC messages can be used to configure the UE to use the SDAP layer device header or its functionality for each PDCP layer device, bearer, or logical channel. If the SDAP header is configured, it can indicate the Non-Access Stratum (NAS) QoS reflection configuration 1-bit indicator (NAS Reflected QoS) and Access Stratum (AS) QoS reflection configuration 1-bit indicator (AS Reflected QoS) in the SDAP header, allowing the UE to update or reconfigure the mapping information of QoS flows and data bearers in the uplink and downlink. The SDAP header can include QoS flow ID information indicating QoS. QoS information can be used for data processing priority, scheduling information, etc., to support smooth service.

[0117] The main functions of NR PDCP S30 or S65 may include some of the following functions.

[0118] - Header compression and decompression: Robust header compression only (ROHC)

[0119] - Transmission of user data

[0120] - Ordered delivery of upper-layer PDUs

[0121] Out-of-order delivery of upper-layer PDUs

[0122] - PDCP PDU reordering for received PDUs

[0123] - Duplicate detection of lower-level service data units (SDUs)

[0124] - PDCP SDU retransmission

[0125] - Encryption and decryption

[0126] - Timer-based SDU dropping in the uplink

[0127] In the aforementioned functions, the reordering of NR PDCP devices refers to the function of reordering PDCP PDUs received from the lower layer in sequence based on the PDCP sequence number (SN), and may include the function of delivering data to the upper layer in the reordered order. Alternatively, the reordering of NR PDCP devices may include the function of transmitting directly regardless of order, the function of reordering the order and recording lost PDCP PDUs, the function of reporting the status of lost PDCP PDUs to the transmitting side, and the function of requesting retransmission of lost PDCP PDUs.

[0128] The main functions of NR RLC S35 or S60 may include some of the following functions.

[0129] - Transmission of upper-layer PDUs

[0130] - Ordered delivery of upper-layer PDUs

[0131] Out-of-order delivery of upper-layer PDUs

[0132] Error correction via Automatic Repeat Request (ARQ)

[0133] - Cascading, segmentation, and reassembly of RLC SDUs

[0134] - Resegmentation of RLC data PDUs

[0135] - Reordering of RLC data PDUs

[0136] - Duplicate Detection

[0137] - Protocol error detection

[0138] - RLC SDU discard

[0139] - RLC Re-establishment

[0140] In the above functions, the in-order delivery of NR RLC devices refers to the function of delivering RLC SDUs received from lower layers to upper layers in sequence. In-order delivery of NR RLC devices may include the following functions: if an original RLC SDU is segmented into multiple RLC SDUs and the segmented RLC SDUs are received, then the RLC SDUs are reassembled and the reassembled RLC SDUs are delivered; it may include the function of reordering received RLC PDUs with reference to the RLC sequence number (SN) or PDCP sequence number (SN); it may include the function of recording RLC PDUs lost due to reordering; it may include the function of reporting the status of lost RLC PDUs to the transmitting side; and it may include the function of requesting retransmission of lost RLC PDUs. In-order delivery of NR RLC devices may include the following functions: if there are lost RLC SDUs, only RLC SDUs preceding the lost RLC SDU are continuously delivered to the higher layer; or it may include the following functions: if a predetermined timer has expired, despite the existence of lost RLC SDUs, all RLC SDUs received before the timer started are continuously delivered to the higher layer. Alternatively, the in-order delivery of NR RLC devices may include the following functionality: if a predetermined timer expires, all RLC SDUs received up to the current time are delivered sequentially to the higher layer, despite the existence of lost RLC SDUs. Furthermore, the in-order delivery of NR RLC devices may process RLC PDUs in the order of reception (regardless of sequence number order, but in the order of arrival) and deliver them to the PDCP device regardless of order (out-of-order delivery). In the case of fragmentation, segments stored in a buffer or to be received later may be received, reconfigured into a complete RLCPDU, processed, and delivered to the PDCP device. The NR RLC layer may not include cascading functionality, which may be performed in the NR MAC layer or replaced by multiplexing functionality of the NR MAC layer.

[0141] In the above functions, out-of-order delivery of NR RLC devices refers to the function of immediately delivering RLC SDUs received from the lower layer to the upper layer without regard to the order. It may include the following functions: if multiple RLC SDUs are received that are segmented from an original RLC SDU, the multiple RLC SDUs are reassembled and delivered; and it may include the function of storing the RLC SN or PDCP SN of the received RLC PDUs and recording RLC PDUs lost due to reordering.

[0142] The NR MAC S40 or S55 can connect to multiple NR RLC layer devices configured in a single UE, and the main functions of the NR MAC can include some of the following functions.

[0143] - Mapping between logical channels and transport channels

[0144] - MAC SDU multiplexing / demultiplexing

[0145] - Scheduling Information Report

[0146] Error correction via Hybrid Automatic Repeat Request (HARQ)

[0147] Priority handling between logical channels of a UE

[0148] - Prioritize UEs through dynamic scheduling

[0149] - Multimedia Broadcast Multicast Service (MBMS) Service Identifier

[0150] - Transmission format selection

[0151] - Fill

[0152] The NR physical (PHY) layer S45 or S50 can perform channel coding and upper-layer data modulation operations to obtain OFDM symbols and deliver them via a wireless channel; or demodulate and decode OFDM symbols received via a wireless channel and deliver them to higher layers.

[0153] The detailed structure of a wireless protocol can be varied depending on the carrier (or cell) operation scheme. For example, when the base station transmits data to the UE based on a single carrier (or cell), the base station and UE can use a protocol structure with a single structure for each layer, such as S00. Conversely, when the base station transmits data to the UE based on carrier aggregation (CA) using multiple carriers in a single transmit-receive point (TRP), the base station and UE can use a protocol structure with a single structure up to the RLC, but multiplexing the PHY layer through the MAC layer, such as S10. As another example, when the base station transmits data to the UE based on dual connectivity (DC) using multiple carriers in multiple TRPs, the base station and UE can use a protocol structure with a single structure up to the RLC, but multiplexing the PHY layer through the MAC layer, such as S20.

[0154] [Regarding UE Capability Report]

[0155] In LTE and NR, a UE can perform the following procedure: while connecting to a serving base station, the UE can report the capabilities it supports to the corresponding base station. In the following description, this procedure will be referred to as UE capability reporting.

[0156] A base station can send a UE capability query message to a UE in a connected state to request capability reports. This message can include UE capability requests for each Radio Access Technology (RAT) type of the base station. Each RAT type UE capability request can include information such as frequency band combinations supported by the UE. Furthermore, for a UE capability query message, a single RRC message container sent by the base station can request UE capabilities for multiple RAT types, or the base station can send a UE capability query message including multiple UE capability requests for various RAT types. That is, a single message can be used to repeat the capability query multiple times, and the UE can configure its corresponding UE capability information message and report the message multiple times. In next-generation mobile communication systems, UE capability requests can be made for multiple RAT dual connectivity (MR-DC) such as NR, LTE, and E-UTRA-NR dual connectivity (EN-DC). Typically, a UE capability query message can be initially sent after the UE connects to the base station, but the base station can request the message under any conditions if required.

[0157] When the UE receives a UE capability report request from the base station in the above steps, the UE configures its capabilities according to the frequency band information and RAT type requested by the base station. The following is an overview of the method for configuring UE capabilities in the NR system.

[0158] 1. If the UE receives a list of LTE and / or NR frequency bands from the base station upon a UE capability request, the UE constructs a frequency band combination (BC) for EN-DC and NR Standalone (SA). That is, the UE configures a BC candidate list for EN-DC and NR SA based on the frequency bands received from the base station upon a FreqBandList request. Furthermore, the frequency bands are prioritized according to the order described in the FreqBandList.

[0159] 2. If the base station sets the “eutra-nr-only” or “eutra” flag and requests a UE capability report, the UE removes all content related to NR SA BC from the configured BC candidate list. This operation can only occur when the LTE base station (eNB) requests “eutra” capability.

[0160] 3. Next, the UE removes the backed-up BC from the BC candidate list configured in the above steps. As used herein, a backed-up BC refers to a BC that can be obtained by removing the frequency band corresponding to at least one secondary cell (SCell) from a specific BC, and since the BC prior to removing the frequency band corresponding to at least one SCell can already cover the backed-up BC, this backed-up BC can be omitted. This step also applies to MR-DC, i.e., LTE frequency bands are also applied. The BCs remaining after this step can constitute the final "candidate BC list".

[0161] 4. The UE can select the BC suitable for the RAT type requested by the base station from the final "Candidate BC List," i.e., the BC to be reported. In this step, the UE configures the supportedBandCombinationList in a defined order. That is, the UE configures the BC to be reported and the UE capabilities according to the pre-configured rat-Type order (nr -> eutra-nr -> eutra). In addition, the UE configures the featureSetCombination for the configured supportedBandCombinationList and configures a list of "Candidate Feature Set Combinations" from the candidate BC list that has removed the list of fallback BCs (including capabilities of the same or lower level). The "Candidate Feature Set Combinations" can include all feature set combinations for NR and EUTRA-NR BCs and can be obtained from the feature set combinations of the containers of UE-NR-Capabilities and UE-MRDC-Capabilities.

[0162] 5. If the requested RAT type is eutra-nr and has an impact, then featureSetCombinations are included in both the UE-MRDC-Capabilities and UE-NR-Capabilities containers. However, the NR feature set is only included in UE-NR-Capabilities.

[0163] After configuring UE capabilities, the UE transmits a UE capability information message, including the UE capabilities, to the base station. Based on the UE capabilities received from the UE, the base station performs scheduling and transmission / reception management suitable for that UE.

[0164] <First Implementation Example: DL CA Scenario Based on Handover>

[0165] [motivation]

[0166] In terms of maximum reach (coverage) achievable by a base station or UE, low-frequency bands of 1 GHz or lower have superior propagation characteristics compared to mid-frequency bands in the 1-3 GHz range or high-frequency bands of 3 GHz or higher. Therefore, they have been effectively used in rural areas where base station installation is difficult or where population density is low (in embodiments of this disclosure, such areas may be defined as a first area). However, low-frequency bands have poorer line-of-sight propagation characteristics and relatively smaller available bandwidth, which are their disadvantages. Conversely, mid-frequency or high-frequency bands have a maximum reach that is not greater than that of low-frequency bands, but offer more advantages in terms of data transmission rate or capacity. Therefore, even though the radio wave reach is not as good as that of low-frequency bands, mid-frequency or high-frequency bands are still useful in urban areas with high radio wave utilization or population density (in embodiments of this disclosure, such areas may be defined as a second area). Based on the propagation characteristics of each band, recent network designs typically deploy mid-frequency or high-frequency bands in urban areas and low-frequency bands in rural areas, and this assumption is actually applied to frequency strategy establishment and mobile communication cell design. However, one of the problems that may be observed in this situation is that when users move from the suburbs to the city or from the city to the suburbs, they frequently stay in the low frequency band instead of the mid frequency band or the high frequency band and perform data or voice communications. In this case, users inevitably use a lower data transmission rate compared to the mid frequency band or the high frequency band, which is the problem of the low frequency band previously mentioned.

[0167] In this context, carrier aggregation (CA) technology can be considered as a method to overcome low data transmission rates. Carrier aggregation is a technique that combines two or more carriers to improve frequency efficiency and maximum transmission rate. Although numerous frequency combinations supporting carrier aggregation have been defined up to 5G, from the perspective of implementing products that actually support carrier aggregation, depending on signal distortion caused by the propagation characteristics of the frequency bands or carriers included in the combination, interference between multiple carriers, or the design of the UE supporting transmission / reception on multiple carriers, there is a possibility that carrier aggregation transmission and reception may be unavailable, or that its performance may be worse than transmission / reception using a single carrier.

[0168] Such carrier aggregation is practically unusable or performs poorly in low-frequency band combinations of 1 GHz or lower. These low-frequency bands have large diffraction characteristics, thus offering good coverage but poor line-of-sight propagation characteristics, which are detrimental to interference control. Similar to other carrier combinations, this combination has been supported in radio access standards since its early stages, but it remains difficult to support from the perspective of UE hardware designed to consider actual propagation characteristics. Given the current UE design approach that needs to support most frequency bands with limited components and resources, solving this propagation characteristic problem is not easy. In current UE hardware implementations that need to support most mobile communication frequency bands within a limited space, low-frequency carrier aggregation may struggle to achieve better performance than typical single-carrier transmission for the following reasons: Figure 6 As shown, from the perspective of the duplexer 603 in the UE hardware that distinguishes between the uplink 601 and downlink 602, uplink and downlink transmissions are typically performed separately in the low-frequency band of 1 GHz or lower according to the frequency division multiplexing (FDD) scheme. The frequency spacing 604 between the uplink and downlink bands in the same frequency band is not significant compared to the propagation characteristics of the low-frequency band, and considering the fractional bandwidth caused by the propagation characteristics of the low-frequency band, the duplexer used to distinguish between the uplink and downlink is not precisely designed. Therefore, the signal transmitted by the UE in the uplink may cause interference 605 in the downlink band. Furthermore, as... Figure 7 As shown, in low-frequency carrier aggregation where multiple low-frequency carriers 701 and 702 are simultaneously transmitted and received, not only the aforementioned problems need to be considered, but also the interference to adjacent frequency bands 703 and 704. Therefore, it is practically difficult for a UE to support low-frequency carrier aggregation. To address the radio propagation characteristics of low-frequency carrier aggregation, a method to minimize interference between multiple frequency bands can be considered through independent antenna and hardware design for each band. However, this method may require additional cost, hardware, and space in the UE, potentially leading to hardware complexity. This constraint on UE implementation hinders the simultaneous use of multiple low-frequency bands and becomes an obstacle to fully utilizing data transmission rates and capacity in areas with high low-frequency band utilization.

[0169] As a method to improve the utilization and efficiency of multiple low-frequency bands, one approach is to switch low-frequency band carrier aggregation to downlink carrier switching and perform transmission and reception. In this way, when transmission / reception is performed alternately with time differences, existing low-frequency band carrier aggregation can be transmitted / received simultaneously, and factors that degrade carrier aggregation performance can be eliminated. The following embodiments specifically describe various scenarios in which the UE transmits and receives low-frequency band carrier aggregation by alternating (switching) between corresponding frequency bands or carriers. In various embodiments of this disclosure, the low-frequency band can be defined as a first frequency band, the mid-frequency band can be defined as a second frequency band, and the high-frequency band can be defined as a third frequency band. Furthermore, since the aforementioned problems mainly occur in the low-frequency band, the following description will focus on describing methods to improve frequency band utilization in the low-frequency band; however, the following methods can also be applied to the mid-frequency band or the high-frequency band. In various embodiments of this disclosure, downlink transmission can refer to base station downlink transmission and UE downlink reception, and uplink transmission can refer to UE uplink transmission and base station uplink reception.

[0170] [Method 1-1]

[0171] If the UE supports downlink carrier aggregation based on inter-carrier handover as described above, three main scenarios can be considered. The first scenario is, as... Figure 8 As shown, during the time period T1 802 when transmit and / or receive operations are performed only in one of the two low-frequency bands (LB) 1 801, it can be configured to perform a receive operation without transmission in the other band LB2 804 in the next time period T2 803. In this case, the other band LB2 804 can represent only downlink transmission in the general FDD band, or it can be a downlink-only band (Supplementary Downlink (SDL)). Figure 8 The example differs from conventional carrier aggregation in that, in either case, during the second time period T2 803, only downlink transmission occurs in one frequency band LB2 804, and no uplink transmission occurs. In this case, at a given moment, transmission and reception can occur only in one frequency band, or only downlink reception can be performed in one frequency band, thus resolving the problems that occur in conventional low-frequency band carrier aggregation. Finally, in the next time period T3 805, the operation as in T1 802 is repeated, and conventional single-band transmission and reception occur.

[0172] [Method 1-2]

[0173] The second method is, such as Figure 9As shown, in time period T1 901, transmission and / or reception are first performed in one frequency band LB1 902, and then in time period T2 903, all uplink transmission is suspended and downlink carrier reception in both frequency bands is performed. Specifically, it can be configured that in time period T2 903, following time period T1 901 where transmission and / or reception operations are performed only in one frequency band LB1 902 in the low-frequency band, reception operations without transmission are performed in both frequency bands LB1 902 and LB2 904. In this case, frequency band LB2 904, as the frequency band operating in the second time period T2 903, can only indicate downlink transmission in the general FDD frequency band, or it can be a downlink-only frequency band (Supplementary Downlink (SDL)). Figure 9 In the example, regardless of the scenario, during the second time period T2 903, only downlink transmission occurs in both frequency bands (LB1 902 and LB2 904), and no uplink transmission occurs, which differs from regular carrier aggregation operations. In this case, transmission and reception occur only in one frequency band at any given time, or only downlink reception is performed in both frequency bands, thus resolving the problems that occur in regular low-frequency carrier aggregation. Finally, in the next time period T3 905, the operation as in T1 901 is repeated, and regular single-band transmission occurs.

[0174] [Methods 1-3]

[0175] The third method is, such as Figure 10 As shown, in time period T1 1001, transmission and / or reception are performed in one frequency band LB1 1002, and in the next time period T2 1003, transmission and / or reception are performed by changing the frequency band to another frequency band LB2 1004. Specifically, in time period T1 1001, where transmission and / or reception operations are performed only in one frequency band LB1 1002 in the low-frequency band, it can be configured to suspend transmission and / or reception in LB1 1002, and in the next time period T2 1003, transmission and / or reception operations are performed in LB2 1004. In this case, since LB2 1004 is the frequency band where both transmission and reception operations occur, therefore... Figure 10 The example may not assume an SDL band. In this example, the difference from regular carrier aggregation operation could be that transmission and reception operations occur only in one band at any given time. In this case, since transmission and reception occur only in one band at any given time without carrier aggregation, the existing problems that occur in regular low-band carrier aggregation can be solved. Finally, in the next time period T3 1005, the operation as in T1 1001 is repeated, and regular single-FDD band transmission occurs.

[0176] Methods 1-1, 1-2, and 1-3 are summarized as follows: When the UE does not support general low-frequency band carrier aggregation, a time-based carrier handover method can be considered as a way to overcome UE hardware limitations while effectively utilizing low-frequency band frequencies. In this case, during the handover scenario, the first time period T1 and the third time period T3 can be fixed as the time periods used for general single-band (LB1) transmission and reception, and the UE can choose one of methods 1-1, 1-2, and 1-3 as a scenario that may occur in the second time period T2, and apply that scenario during T2.

[0177] In methods 1-1, 1-2, and 1-3 above, the statement "to send in a specific LB during a specific time period (T)" means that sending is available in the corresponding LB during that time period, but it does not mean that sending will always occur. In other words, when a sending schedule exists, a sending operation can be performed according to that schedule. Similarly, the statement "to receive in a specific LB during a specific time period (T)" means that receiving is available in the corresponding LB during that time period, but it does not mean that receiving will always occur. That is, when a receiving schedule exists, a receiving operation can be performed according to that schedule.

[0178] <Second Embodiment: Method for configuring UE capabilities based on UE architecture supporting handover-based DL CA>

[0179] The following description will detail the following method: When the UE performs handover-based downlink carrier aggregation to maximize frequency efficiency, based on the UE's hardware architecture or other reasons, the UE selects one of the three scenarios mentioned above where the UE supports low-frequency band carrier aggregation through downlink carrier handover, reports the selected scenario as a UE capability, and describes the operations performed by the UE and the base station based on the UE capability report.

[0180] First, the carrier aggregation combination that the UE performs based on inter-carrier handover operations in low-frequency band carrier aggregation can be configured together with other combinations used for general carrier aggregation. Furthermore, the UE can report the frequency band combinations capable of performing handover-based downlink reception for each frequency band combination via a new UE capability [DLRxSwitchingBandPair], and can select handover options supported by the UE, reporting them to the base station via UE sub-capabilities of [DLRxSwitchingBandPair], such as [downlinkRxSwitchingPeriod1], [downlinkRxSwitchingPeriod2], or [downlinkRxSwitchingPeriod3]. In various embodiments of this disclosure, [downlinkRxSwitchingPeriod1] may correspond to the capability indicating the handover option of method 1-1, [downlinkRxSwitchingPeriod2] may correspond to the capability indicating the handover option of method 1-2, and [downlinkRxSwitchingPeriod3] may correspond to the capability indicating the handover option of method 1-3. If the base station instructs the UE to receive one of the combinations reported via [DLRxSwitchingBandPair], the UE can operate as follows, based on the UE capabilities [downlinkRxSwitchingPeriod1], [downlinkRxSwitchingPeriod2], or [downlinkRxSwitchingPeriod3] reported with it. In various embodiments of this disclosure, parameters such as DLRxSwitchingBandPair and downlinkRxSwitchingPeriod are used to describe the aforementioned UE capabilities, and the names of the parameters are not limited thereto.

[0181] - [Method 2-1] Switching to downlink reception operation only in band LB2 during time period T2: If the UE supports [Method 1-1] via [downlinkRxSwitchingPeriod1], for example, if [downlinkRxSwitchingPeriod1] exists, then based on the handover reception of carrier aggregation across two corresponding bands, the base station can schedule both downlink and uplink in band LB1 during the first time period T1, and schedule only downlink in band LB2 during the second time period T2. From the next time period T3, the operations performed as in time periods T1 and T2 can be scheduled alternately and repeatedly until the transmission of the bandwidth combination of the corresponding combination terminates. In this case, the UE follows the base station's scheduling instructions, and as previously stated, the SDL band as a downlink-only band is considered to be band LB2, but band LB2 is not limited to this and can be extended to general FDD bands.

[0182] - [Method 2-2] Case where downlink reception operation is switched to combined frequency bands LB1 and LB2 during time period T2: If the UE supports [Method 1-2] via [downlinkRxSwitchingPeriod2], for example, if [downlinkRxSwitchingPeriod2] exists, then based on the switch to receive carrier aggregation across frequency bands LB1 and LB2, the base station can schedule both downlink and uplink in a single frequency band of frequency band LB1 during the first time period T1, and schedule only downlink carrier aggregation via combined frequency bands LB1 and LB2 during the second time period T2. From the next time period T3, the operations performed as in time periods T1 and T2 can be scheduled alternately and repeatedly until the transmission of the bandwidth combination of the corresponding combination terminates. In this case, the UE follows the base station's scheduling instructions, and as previously stated, the SDL frequency band as a downlink-only frequency band is considered to be frequency band LB2, but frequency band LB2 is not limited to this and can be extended to general FDD frequency bands.

[0183] - [Method 2-3] Switching to band LB2 during time period T2: If the UE supports [Method 1-3] via [downlinkRxSwitchingPeriod3], for example, if [downlinkRxSwitchingPeriod3] exists, then based on the handover reception of carrier aggregation across two corresponding bands, the base station can schedule both downlink and uplink in a single band of band LB1 during the first time period T1, and switch to band LB2 during the second time period T2, scheduling both downlink and uplink in a single band. From the next time period T3, the operations performed as in time periods T1 and T2 can be scheduled alternately and repeatedly until the transmission of the corresponding combination of bandwidths terminates. In this case, the UE follows the base station's scheduling instructions, and only the general FDD band can be considered as band LB2.

[0184] In summary, considering the design of the UE's hardware, receiver, etc., the UE can configure itself whether to support low-frequency carrier aggregation (or the UE capability used for such low-frequency carrier aggregation), and can include in the BandCombinationList the frequency band combinations that can be supported by handover, as well as a list of existing carrier aggregation frequency band combinations, and can report this to the base station. In various embodiments of this disclosure, it has been described that information associated with frequency band combinations that can be supported by handover is included in the BandCombinationList and reported; however, this disclosure is not limited thereto, and does not exclude the inclusion of such information in other information fields of messages used to report UE capability information. Specifically, a list of carrier aggregations that can be supported based on handover can be reported separately for each frequency band combination via [DLRxSwitchingBandPair], and one or more of the supported handover options in [downlinkRxSwitchingPeriod1], [downlinkRxSwitchingPeriod2], or [downlinkRxSwitchingPeriod3] can also be reported to the base station. In this scenario, when the base station indicates the UE to the list of combinations included in [DLRxSwitchingBandPair], the base station can configure scheduling based on information included in [downlinkRxSwitchingPeriod1], [downlinkRxSwitchingPeriod2], or [downlinkRxSwitchingPeriod3]. For example, when the base station schedules combinations included in [DLRxSwitchingBandPair] for the UE, the base station can indicate to the UE from the carrier aggregation transmission start time period T1 that uplink and downlink transmission and / or reception are performed only in one frequency band LB1, and the UE can perform uplink transmission and downlink reception in the frequency band LB1 indicated by the base station. During time period T2, the base station can determine, by referring to [downlinkRxSwitchingPeriod1], [downlinkRxSwitchingPeriod2], or [downlinkRxSwitchingPeriod3] reported by the UE along with [DLRxSwitchingBandPair], whether to schedule only downlink in band LB2 (method 2-1), or to schedule only downlink transmission by combining bands LB1 and LB2 (method 2-2), or to switch to band LB2 and schedule both uplink and downlink (method 2-3). The UE can then perform uplink transmission and / or downlink reception based on the configuration determined by the base station.

[0185] <Third Implementation Example: Handover Time and Time Period Configuration and Signaling / UE Capability Reporting Method>

[0186] The following description details a method for configuring handover conditions when the UE performs low-frequency carrier aggregation downlink reception based on handover. For example, it configures the location of changes occurring from T1 to T2 or from T2 to T3 within a carrier reception time period and reports this as a UE capability to the base station. Furthermore, it details a method for configuring a maximum time period during which the base station does not perform downlink transmission, enabling the UE to change its receiver during handover and report this as a UE capability to the base station.

[0187] As described above, the UE can configure the handover combination for which handover operations are applied in the low-frequency band carrier combination in the BandCombinationList, which also supports other combinations for general carrier aggregation. Furthermore, the UE can report the corresponding downlink-based handover combination through the new UE capability [DLRxSwitchingBandPair]. In this case, the UE can configure the location and time period of the handover from T1 to T2, or from T2 to T3, and report it to the base station as a UE capability.

[0188] For example, handover periods that can be reported by the UE through the new UE capabilities [downlinkRxSwitchingPeriod1], [downlinkRxSwitchingPeriod2], or [downlinkRxSwitchingPeriod3] can typically be in units of symbols included in the carrier and can be converted to time units based on the subcarrier spacing (SCS) supporting that handover period. That is, the handover period that can be reported by the UE through the UE capability [downlinkRxSwitchingPeriod] can be at least one symbol time and an integer multiple thereof, and this may be due to UE implementations such as the UE receiver hardware architecture. Typically, depending on the supported frequency bands and the receiver architecture for each band, and when a single receiver supports only a single frequency band, the receiver control time can be reduced compared to a single receiver architecture designed to support multiple frequency bands. In this way, to support various UE designs, the handover time that can be reported by the UE to the base station through the UE capability [downlinkRxSwitchingPeriod] can be one of the values ​​in Table 11 based on the SCS.

[0189] [Table 11]

[0190]

[0191] Based on the above embodiments and [Table 11], the new UE capability [DLRxSwitchingBandPair] can be reported as shown in [Table 12] below.

[0192] [Table 12]

[0193]

[0194] Furthermore, the location of the handover from T1 to T2 or from T2 to T3 can be configured via RRC, and the time period during which the handover may occur can be configured in various ways, taking into account carrier type and other downlink channels. For example, in one embodiment of this disclosure, such as Figure 12 As shown, considering the characteristic that the downlink control channel (PDCCH) necessary for the base station to control the UE is arranged at the beginning of the downlink time slot, it can be assumed that the handover operation occurs from the handover time (Xus) 1202 before the last part (S0) 1201 of the carrier time slot, where the handover time (Xus) 1202 is reported by the UE via [downlinkRxSwitchingPeriod1], [downlinkRxSwitchingPeriod2], or [downlinkRxSwitchingPeriod3]. In this case, the UE can configure [downlinkRxSwitchingPeriodLocation] to TRUE. If it is assumed that the UE does not start the handover from the time S0-X (us) before the end of the downlink carrier time slot, but performs the handover at another carrier location, the UE can report [downlinkRxSwitchingPeriodLocation] as FALSE. In the various embodiments of this disclosure, downlinkRxSwitchingPeriodLocation is merely an example used to describe the above functions, and the names of the parameters are not limited thereto.

[0195] In summary, when low-frequency band carrier aggregation is supported through inter-carrier handover, the UE can operate as follows for each scenario.

[0196] [Method 3-1]

[0197] like Figure 11As shown, if inter-band downlink carrier aggregation is configured and the UE capability [downlinkRxSwitchingPeriod1] 1101 exists, specifically, if the two downlink carriers are located in different frequency bands, the UE can support handover between the two downlink carriers in the time domain according to the base station's scheduling instructions and rank adaptation. Here, supporting handover between two downlink carriers means that in the first time period T1, a time difference handover occurs between the uplink carrier UL1 and downlink carrier DL1 in frequency band LB1 and the downlink carrier DL2 in frequency band LB2. In this case, the UE needs to support Layer 2 reception in both the downlink carriers DL1 1102 and DL2 1103 associated with the handover, and also needs to support single-layer transmission using one antenna port for each of them. Here, carrier DL2 can be a carrier in a general frequency band where both uplink and downlink transmission are available, or it can be a carrier in a downlink-only frequency band (SDL). In other words, the layer of the downlink carriers supported at any given time is the same.

[0198] like Figure 12 As shown, the location of the switchable period in which the UE can perform a handover can be the handover time X 1202 before the start point 1201 of each of the downlink carriers DL1 and DL2, as indicated by the base station via RRC signaling [downlinkRxSwitchingPeriodLocation]. Here, the downlink handover length X needs to be less than [downlinkRxSwitchingPeriod1] reported as the UE capability.

[0199] In the case of switching from one carrier to another, if downlink transmission on the carrier before the switch is not scheduled or configured at least X μs before the UE is scheduled or configured to start receiving on the carrier after the switch, the switching time must be fully included in the time gap between the end time of reception on the carrier before the switch and the start time of reception on the carrier after the switch.

[0200] [Method 3-2]

[0201] like Figure 11As shown, if inter-band downlink carrier aggregation is configured and UE capability [downlinkRxSwitchingPeriod2] 1104 exists, specifically, if the two downlink carriers are located in different frequency bands, the UE can support handover between the two downlink carriers in the time domain according to the base station's scheduling instructions and rank adaptation. Here, supporting handover between two downlink carriers means that in the first time period T1, a time difference handover is performed between the uplink carrier UL1 and the downlink carrier DL1 in frequency band LB1, and in the second time period T2, a time difference handover is performed between the downlink carrier DL1 in frequency band LB1 and the downlink carrier DL2 in frequency band LB2. In this case, the UE needs to support at least one layer of reception in the downlink carriers DL1 1105 and DL2 1106 associated with the handover. Here, carrier DL2 can be a carrier in a general frequency band where both uplink and downlink transmission and reception are available, or it can be a carrier in a downlink-only frequency band (SDL). That is, the total number of downlink carrier layers supported at any given time is the same.

[0202] like Figure 12 As shown, the location of the switchable period in which the UE can perform a handover can be the handover time X 1202 before the start point 1201 of each of the downlink carriers DL1 and DL2, as indicated by the base station via RRC signaling [downlinkRxSwitchingPeriodLocation]. Here, the downlink handover length X needs to be less than [downlinkRxSwitchingPeriod2] reported as the UE capability.

[0203] In the case of switching from one carrier to another, if downlink transmission on the carrier before the switch is not scheduled or configured at least X μs before the UE is scheduled or configured to start receiving on the carrier after the switch, the switching time must be fully included in the time gap between the end time of reception on the carrier before the switch and the start time of reception on the carrier after the switch.

[0204] [Method 3-3]

[0205] like Figure 11As shown, if inter-band downlink carrier aggregation is configured and UE capability [downlinkRxSwitchingPeriod3] 1107 exists, specifically, if the two downlink carriers are located in different frequency bands, the UE can support handover between the two downlink carriers in the time domain according to the base station's scheduling instructions and rank adaptation. Here, supporting handover between two downlink carriers means that in the first time period T1, a time difference handover occurs between the uplink carrier UL1 and the downlink carrier DL1 of band LB1, and in the second time period T2, a time difference handover occurs between the uplink carrier UL2 and the downlink carrier DL2 of band LB2. In this case, the UE needs to support Layer 2 reception in both the downlink carriers DL1 1102 and DL2 1108 associated with the handover, and also needs to support single-layer transmission using one antenna port for each of them. That is, the total number of downlink carrier layers supported at a given time is the same.

[0206] like Figure 12 As shown, the location of the switchable period in which the UE can perform a handover can be the handover time X 1202 before the start point 1201 of each of the downlink carriers DL1 and DL2, as indicated by the base station via RRC signaling [downlinkRxSwitchingPeriodLocation]. Here, the downlink handover length X needs to be less than [downlinkRxSwitchingPeriod3] reported as the UE capability.

[0207] In the case of switching from one carrier to another, if downlink transmission on the carrier before the switch is not scheduled or configured at least X μs before the UE is scheduled or configured to start receiving on the carrier after the switch, the switching time must be fully included in the time gap between the end time of reception on the carrier before the switch and the start time of reception on the carrier after the switch.

[0208] Although embodiments 1, 2, and 3 have been described above, this is for ease of description, and all embodiments 1, 2, and 3 provide methods for effectively using a carrier wave according to this disclosure. Therefore, embodiments 1, 2, and 3 can be implemented independently and can also be combined with each other. In particular, based on the description of the embodiments, those skilled in the art will understand that combinations of methods 1-1, 2-1, and 3-1, methods 1-2, 2-2, and 3-2, and methods 1-3, 2-3, and 3-3 are available.

[0209] For example, in one embodiment of this disclosure, the UE can determine its capability for carrier handover. For example, scenarios for carrier handover may exist, such as methods 1-1, 1-2, and 1-3. This UE capability can be determined based on the UE's hardware limitations, frequency band characteristics, characteristics of the surrounding area, etc.

[0210] The UE capabilities used to support the above scenarios can be reported to the base station according to the method of the second embodiment. For example, the base station can send a UE capability report request message to the UE. In response to the UE capability report request message, the UE can send UE capability information to the base station. The UE capability information may include information related to carrier handover. For example, it may include the DLRxSwitchingBandPair described in the second embodiment, information corresponding to the DLRxSwitchingBandPair, the downlinkRxSwitchingPeriod described in the third embodiment, and the information described in Table 12.

[0211] Meanwhile, information related to carrier handover can be indicated through explicit information or through implicit methods. For example, by reporting carrier handover-related information to the base station, the base station can determine that the corresponding UE has carrier handover capability.

[0212] The UE can report UE capability information to the base station according to the above method, and the base station that has received the UE capability information can perform carrier handover-based scheduling operations based on the UE capability information. For example, the UE and the base station can perform capability information reporting and scheduling operations according to the methods described in method 2-1, method 2-2 or method 2-3.

[0213] When a handover occurs according to this method, carrier handover can be performed at the handover time point identified according to method 3-1, method 3-2 or method 3-3 as described in the third embodiment.

[0214] The first embodiment, the second embodiment, and / or the third embodiment can be implemented in combination with each other.

[0215] The flowchart above illustrates an exemplary method that can be implemented according to the principles of this disclosure, and various modifications can be made to the method shown in the flowchart of the specification. For example, although shown as a series of steps, the steps in the various figures may overlap, occur in parallel, occur in different orders, or occur multiple times. In other examples, individual steps may be omitted or replaced by other steps.

[0216] Figure 13 The structure of a UE in a wireless communication system according to an embodiment of the present disclosure is shown.

[0217] Reference Figure 13The UE may include a transceiver (which collectively refers to UE receiver 1300 and UE transmitter 1310), a memory (not shown), and a UE processor 1305 (or UE controller or processor). The transceivers 1300 and 1310, the memory, and the UE processor 1305 of the UE can operate according to at least one or a combination of methods corresponding to the embodiments described above. However, the components of the UE are not limited to the examples shown. For example, the UE may include more or fewer components than those described above. Furthermore, in certain cases, the transceiver, memory, and processor may be implemented as a single chip.

[0218] Transceivers 1300 and 1310 can transmit / receive signals with a base station. These signals may include control information and data. For this purpose, transceivers 1300 and 1310 may include an RF transmitter and an RF receiver, the RF transmitter being configured to up-convert and amplify the frequency of the transmitted signal, and the RF receiver being configured to perform low-noise amplification and down-convert the frequency of the received signal. However, this is merely an embodiment of transceivers 1300 and 1310, and the components of transceivers 1300 and 1310 are not limited to RF transmitters and RF receivers.

[0219] In addition, transceivers 1300 and 1310 can receive signals via a wireless channel, output signals to processor 1305, and transmit signals output from processor 1305 via a wireless channel.

[0220] The memory can store programs and data required for the operation of the UE. Additionally, the memory can store control information or data included in signals sent / received by the UE. The memory can include storage media such as ROM, RAM, hard disk, CD-ROM, and DVD, or combinations of storage media. Furthermore, the memory can include multiple memories.

[0221] Furthermore, processor 1305 can control a series of processes enabling the UE to operate according to the above embodiments. For example, processor 1305 can execute or control the operation of the UE to perform at least one or a combination of methods according to embodiments of this disclosure. Processor 1305 may include multiple processors, and the processors can perform control operations on components of the UE by executing programs stored in memory.

[0222] Figure 14 The structure of a base station in a wireless communication system according to an embodiment of the present disclosure is shown.

[0223] Reference Figure 14The base station may include transceivers (which collectively refer to base station receiver 1400 and base station transmitter 1410), memory (not shown), and base station processor 1405 (or base station controller or processor). The transceivers 1400 and 1410, memory, and base station processor 1405 of the base station can operate according to at least one or a combination of methods corresponding to the above embodiments. However, the components of the base station are not limited to the examples shown. For example, the base station may include more or fewer components than those described above. Furthermore, the transceivers, memory, and processor may be implemented as a single chip.

[0224] Transceivers 1400 and 1410 can transmit / receive signals with the UE. These signals may include control information and data. For this purpose, transceivers 1400 and 1410 may include an RF transmitter and an RF receiver, the RF transmitter being configured to up-convert and amplify the frequency of the transmitted signal, and the RF receiver being configured to perform low-noise amplification and down-convert the frequency of the received signal. However, this is merely one embodiment of transceivers 1400 and 1410, and the components of transceivers 1400 and 1410 are not limited to RF transmitters and RF receivers.

[0225] In addition, transceivers 1400 and 1410 can receive signals via a wireless channel, output signals to processor 1405, and transmit signals output from processor 1405 via a wireless channel.

[0226] The memory can store programs and data required for the operation of the base station. Additionally, the memory can store control information or data included in signals transmitted / received by the base station. The memory can include storage media such as ROM, RAM, hard disks, CD-ROMs, and DVDs, or combinations of storage media. Furthermore, the memory can include multiple memories.

[0227] Processor 1405 can control a series of processes enabling the base station to operate according to the embodiments of the present disclosure described above. For example, processor 1405 can execute or control the operation of the base station to perform at least one or a combination of methods according to the embodiments of the present disclosure. Processor 1405 may include multiple processors, and the processors can perform control operations on components of the base station by executing programs stored in memory.

[0228] The methods disclosed in the claims or the methods of the embodiments described in this disclosure may be implemented by hardware, software, or a combination of hardware and software.

[0229] When implemented in software, a computer-readable storage medium may be provided for storing one or more programs (software modules). One or more programs stored in the computer-readable storage medium may be configured to be executed by one or more processors within an electronic device. At least one program includes instructions to cause the electronic device to perform methods as defined by the appended claims and / or as disclosed herein according to various embodiments of this disclosure.

[0230] These programs (software modules or software) can be stored in non-volatile memory including random access memory and flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), disk storage devices, read-only storage optical discs (CD-ROM), digital versatile optical discs (DVDs), or other types of optical storage devices, or magnetic tape. Alternatively, the programs can be stored in memory configured as a combination of some or all of these. Furthermore, multiple such memories may be included.

[0231] Furthermore, the program can be stored in an attachable storage device that can access the electronic device via a communication network such as the Internet, intranet, local area network (LAN), wide area network (WLAN), and storage area network (SAN), or a combination thereof. Such a storage device can access the electronic device via an external port. Additionally, a separate storage device on the communication network can access the device executing embodiments of this disclosure.

[0232] In the detailed embodiments described above, elements included in this disclosure are represented in singular or plural form according to the presented detailed embodiments. However, for ease of description, the singular or plural form may be appropriately chosen depending on the presented situation, and this disclosure is not limited to elements represented in singular or plural form. Therefore, an element represented in plural form may also include a single element, or an element represented in singular form may include multiple elements.

[0233] The embodiments of this disclosure described and illustrated in the specification and drawings are merely specific examples presented to facilitate the explanation of the technical content of this disclosure and to aid in understanding it, and are not intended to limit the scope of this disclosure. That is, it will be apparent to those skilled in the art that other variations based on the technical concept of this disclosure can be implemented. Furthermore, the corresponding embodiments described above can be combined as needed. As an example, a portion of one embodiment of this disclosure can be combined with a portion of another embodiment to operate a base station and a terminal. As an example, a portion of a first embodiment of this disclosure can be combined with a portion of a second embodiment to operate a base station and a terminal. Moreover, although the above embodiments have been described based on an FDD LTE system, other variations of the technical concept based on the embodiments can also be implemented in other communication systems such as Time Division Duplex (TDD) LTE and 5G or NR systems.

[0234] In the accompanying drawings describing the methods of this disclosure, the order of description does not always correspond to the order in which the steps of each method are performed, and the order of the steps may be changed, or the steps may be performed in parallel.

[0235] Alternatively, in the accompanying drawings describing the methods of this disclosure, some elements may be omitted and only some elements may be included without departing from the basic spirit and scope of this disclosure.

[0236] Furthermore, in the methods of this disclosure, some or all of the contents of each embodiment may be combined to implement them without departing from the basic spirit and scope of this disclosure.

[0237] Various embodiments of this disclosure have been described above. The above description of this disclosure is for illustrative purposes and is not intended to limit the embodiments of this disclosure to those set forth herein. Those skilled in the art will understand that other specific modifications and changes can be readily made to the form of this disclosure without altering the technical concept or essential characteristics of this disclosure. The scope of this disclosure is defined by the appended claims rather than the detailed description above, and the scope of this disclosure should be construed as including all changes or modifications derived from the meaning and scope of the claims and their equivalents.

Claims

1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising: Receive UE capability query message from base station; as well as Based on the receipt of the UE capability query message, a UE capability information message is sent to the base station. The UE capability information message includes first information, which indicates support for low-band-low-band (LB-LB) carrier aggregation (CA) based on handover between a first low-band (LB) supporting frequency division duplex (FDD) and a second LB supporting supplementary downlink (SDL). Specifically, based on the first information, during a first time period in which transmission or reception is performed in the FDD band of the first LB, reception is not performed in the SDL band of the second LB, and during a second time period in which reception is performed in the SDL band of the second LB, transmission or reception is not performed in the FDD band of the first LB.

2. The method according to claim 1, wherein, The UE capability information message includes second information, which indicates the length of the handover time between the first LB and the second LB, and The switching time is measured in microseconds.

3. The method according to claim 2, wherein, The switching between the first LB and the second LB is performed in the last time slot of the first time period.

4. The method according to claim 1, wherein, The UE capability information message includes second information, which indicates support for the LB-LB CA based on handover between the first LB supporting the FDD and the second LB supporting the SDL. Specifically, based on the second information, reception is not performed in the SDL of the second LB during the first time period, and reception operation of the first LB is performed during the second time period.

5. A method performed by a base station in a wireless communication system, the method comprising: Send a UE capability query message to the user equipment (UE); as well as Based on the transmission of the UE capability query message, a UE capability information message is received from the UE. The UE capability information message includes first information, which indicates support for low-band-low-band (LB-LB) carrier aggregation (CA) based on handover between a first low-band (LB) supporting frequency division duplex (FDD) and a second LB supporting supplemental downlink (SDL). Specifically, based on the first information, during a first time period in which transmission or reception is performed in the FDD band of the first LB, reception is not performed in the SDL band of the second LB, and during a second time period in which reception is performed in the SDL band of the second LB, transmission or reception is not performed in the FDD band of the first LB.

6. The method according to claim 5, wherein, The UE capability information message includes second information, which indicates the length of the handover time between the first LB and the second LB, and The switching time is measured in microseconds.

7. The method according to claim 6, wherein, The switching between the first LB and the second LB is performed in the last time slot of the first time period.

8. The method according to claim 5, wherein, The UE capability information message includes second information, which indicates support for the LB-LB CA based on handover between the first LB supporting the FDD and the second LB supporting the SDL. Specifically, based on the second information, reception is not performed in the SDL of the second LB during the first time period, and reception operation of the first LB is performed during the second time period.

9. A user equipment (UE) in a wireless communication system, the UE comprising: Memory, used to store instructions; as well as A processing circuit, connected to the memory, is configured to cause the UE to: (at least in part) cause the UE to: Receive UE capability query message from base station, and Based on the receipt of the UE capability query message, a UE capability information message is sent to the base station. The UE capability information message includes first information, which indicates support for low-band-low-band (LB-LB) carrier aggregation (CA) based on handover between a first LB that supports frequency division duplex (FDD) and a second LB that supports supplementary downlink (SDL). Specifically, based on the first information, during a first time period in which transmission or reception is performed in the FDD band of the first LB, reception is not performed in the SDL band of the second LB, and during a second time period in which reception is performed in the SDL band of the second LB, transmission or reception is not performed in the FDD band of the first LB.

10. The UE according to claim 9, wherein, The UE capability information message includes second information, which indicates the length of the handover time between the first LB and the second LB, and The switching time is measured in microseconds.

11. The UE according to claim 10, wherein, The switching between the first LB and the second LB is performed in the last time slot of the first time period.

12. The UE according to claim 9, wherein, The UE capability information message includes second information, which indicates support for the LB-LB CA based on handover between the first LB supporting the FDD and the second LB supporting the SDL. Specifically, based on the second information, reception is not performed in the SDL of the second LB during the first time period, and reception operation of the first LB is performed during the second time period.

13. A base station in a wireless communication system, the base station comprising: Memory, used to store instructions; as well as A processing circuit, connected to the memory, is configured to cause the base station to: (at least in part) cause the base station to: Send a UE capability query message to the user equipment (UE), and Based on the transmission of the UE capability query message, a UE capability information message is received from the UE. The UE capability information message includes first information, which indicates support for low-band-low-band (LB-LB) carrier aggregation (CA) based on handover between a first LB supporting frequency division duplex (FDD) and a second LB supporting supplemental downlink (SDL). Specifically, based on the first information, during a first time period in which transmission or reception is performed in the FDD band of the first LB, reception is not performed in the SDL band of the second LB, and during a second time period in which reception is performed in the SDL band of the second LB, transmission or reception is not performed in the FDD band of the first LB.

14. The base station according to claim 13, wherein, The UE capability information message includes second information, which indicates the length of the handover time between the first LB and the second LB, and The switching time is measured in microseconds.

15. The base station according to claim 14, wherein, The switching between the first LB and the second LB is performed in the last time slot of the first time period.

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