METHOD AND APPARATUS FOR UE TYPE-BASED BWP OPERATION IN WIRELESS COMMUNICATION SYSTEM - Patent application

Abstract

A method is provided for a BWP operation performed by a user equipment (UE) in a wireless communication system. The present invention relates to a 5G or 6G communication system for supporting higher data transmission rates. A method is provided which is performed by a user equipment (UE) in a wireless communication system. The method includes the steps of: identifying that a random access procedure has been initiated in a serving cell; selecting an uplink (UL) carrier for the serving cell; if a physical random access channel (PRACH) occasion is not configured for an active UL bandwidth portion (BWP) of the selected UL carrier, identifying whether an initial UL BWP for a reduced capability (RedCap) UE is configured; and if the initial UL BWP for the RedCap UE is configured, switching the active UL BWP to the initial UL BWP for the RedCap UE.

Description

[Technical field]

[0001] The present invention relates to a wireless communication system, and more particularly to an apparatus, method and system for user equipment (UE) type based bandwidth part (BWP) operation in a wireless communication system. [Background technology]

[0002] 5G mobile communication technology defines a wide frequency band to enable faster transmission speeds and new services, and can be implemented in frequencies below 6GHz ('Sub 6GHz') such as 3.5GHz, as well as ultra-high frequency bands ('Above 6GHz') called millimeter wave (mmWave) such as 28GHz and 39GHz. In addition, in the case of 6G mobile communication technology, known as the system after 5G communication (Beyond 5G), implementation in the terahertz band (for example, 95GHz to 3THz band) is being considered to achieve transmission speeds 50 times faster than 5G mobile communication technology and ultra-low latency that is 1 / 10th of that.

[0003] In the early stage of 5G mobile communications technology, the following technologies will be developed to support services and satisfy performance requirements for enhanced Mobile BroadBand (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC): Beamforming and Massive MIMO (Multiple-Input Multiple-Output) to mitigate path loss in ultra-high frequency bands and increase transmission distance, various numerology support (e.g., multiple subcarrier spacing control) and dynamic control of slot format for efficient use of ultra-high frequency resources, initial connection technology to support multiple beam transmission and wideband, definition and operation of BWP (Band-Width Part), new channel coding methods such as LDPC (Low Density Parity Check) code for large volume data transmission and Polar Code for reliable transmission of control information, L2 pre-processing, and Network Slicing to provide a dedicated network specialized for specific services. Standardization of techniques such as slicing has progressed.

[0004] Discussions are currently underway for the initial improvement and enhancement of 5G mobile communications technology in consideration of the services that 5G mobile communications technology will support. Physical layer standardization is underway for technologies such as Vehicle-to-Everything (V2X), which aims to increase user convenience by helping autonomous vehicles make driving decisions based on their own position and status information transmitted by the vehicle, New Radio Unlicensed (NR-U), which aims to operate systems in unlicensed bands in accordance with various regulatory requirements, low power consumption technology for NR terminals (UE Power Saving), Non-Terrestrial Network (NTN), which is direct communication between terminals and satellites to ensure coverage in areas where communication with terrestrial networks is not possible, and positioning.

[0005] In addition, standardization is underway in the areas of radio interface architecture / protocol for technologies such as Industrial Internet of Things (IIoT) to support new services through collaboration and integration with other industries, Integrated Access and Backhaul (IAB) to provide nodes for expanding network service areas by integrating wireless backhaul links and access links, mobility enhancement technologies including Conditional Handover and Dual Active Protocol Stack (DAPS) handover, and 2-step random access (2-step RACH for NR) to simplify random access procedures. Standardization is also underway in the areas of system architecture / service for 5G baseline architecture (e.g., Service based Architecture, Service based Interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) in which services are provided based on the location of the terminal.

[0006] As 5G mobile communication systems are commercialized, the number of connected devices, which is increasing explosively, will be connected to communication networks, which will require the enhancement of the functions and performance of 5G mobile communication systems and the integrated operation of connected devices.To this end, new research will be conducted on 5G performance improvement and complexity reduction using eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), Mixed Reality (MR), etc., AI service support, Metabus service support, drone communication, etc.

[0007] In addition, the development of such 5G mobile communication systems will be the basis for the development of multiple antenna transmission technologies such as new waveforms, full dimensional MIMO (FD-MIMO), array antennas, and large scale antennas to ensure coverage in the terahertz band of 6G mobile communication technology, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using orbital angular momentum (OAM), and reconfigurable intelligent surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, AI-based communication technology that utilizes satellites and artificial intelligence (AI) from the design stage to internalize end-to-end AI support functions to optimize the system, and next-generation distributed computing technology that utilizes ultra-high performance communication and computing resources to realize services with a level of complexity that exceeds the limits of terminal computing capabilities. Summary of the Invention [Problem to be solved by the invention]

[0008] In the current design, one initial uplink bandwidth part (BWP) and one initial downlink BWP are configured for a cell. The evolution of wireless communication systems requires improved BWP operation for UEs with limited capabilities. [Means for solving the problem]

[0009] Aspects of the present invention are directed to solving at least the problems and / or shortcomings mentioned above and providing at least the advantages described below. Accordingly, one aspect of the present invention is to provide a communication method and system for merging 5G communication systems to support higher data transmission rates over 4G communication systems.

[0010] According to an aspect of the present invention, there is provided a method performed by a user equipment (UE) in a wireless communication system, the method including: identifying that a random access procedure has been initiated in a serving cell; selecting an uplink (UL) carrier for the serving cell; if a physical random access channel (PRACH) occasion is not configured for an active UL bandwidth part (BWP) of the selected UL carrier, identifying whether an initial UL BWP for a reduced capability (RedCap) UE is configured; and, if the initial UL BWP for the RedCap UE is configured, switching the active UL BWP to the initial UL BWP for the RedCap UE.

[0011] According to another aspect of the present invention, there is provided a UE in a wireless communication system, the UE including: a transceiver unit; and a controller operatively connected to the transceiver unit, the controller is configured to: identify that a random access procedure is initiated in a serving cell, select a UL carrier for the serving cell, identify whether an initial UL BWP for a RedCap UE is configured if a PRACH occasion is not configured for an active UL BWP of the selected UL carrier, and switch the active UL BWP to the initial UL BWP for the RedCap UE if the initial UL BWP for the RedCap UE is configured. Effect of the Invention

[0012] According to the present invention, the BWP operation can be performed efficiently. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating the structure of a next-generation mobile communication system according to various embodiments of the present invention. [Diagram 2] 2 is a diagram illustrating a radio protocol structure of a next-generation mobile communication system according to various embodiments of the present invention. [Diagram 3] 1 is a diagram illustrating an example of setting a bandwidth portion in a wireless communication system according to various embodiments of the present invention. [Figure 4] A diagram showing an example of BWP switching when a random access procedure is initiated according to various embodiments of the present invention. [Diagram 5] A diagram showing an example of BWP switching when a BWP inactivity timer expires according to various embodiments of the present invention. [Figure 6] 1 illustrates a block diagram of a terminal according to various embodiments of the present invention; [Figure 7] FIG. 2 illustrates a block diagram of a base station according to various embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Before proceeding with the detailed description below, certain words and phrases used throughout this specification are defined. The terms "include" and "comprise," along with their derivatives, are meant to include without limitation. The term "or" refers inclusively to and / or. As well as the term "associated therewith," derivatives thereof mean "include," "be included within," "interconnect with," "contain," "be contained within," "connect to or with," "couple to or with," "be communicable with," "cooperate with," "interleave," "juxtapose with," "be proximate to," "be bound to or with," "have," and "have a property of." The term "controller" means any device, system, or portion thereof that controls at least one operation, and such a device may be embodied in hardware, firmware, or software, or a combination of at least two of these. The functionality associated with any particular controller may be centralized or distributed, whether locally or remotely.

[0015] Moreover, various functions described below may be embodied or supported by one or more computer programs, each computer program being formed from computer-readable program code and embodied in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, associated data, or portions thereof, adapted for implementation in suitable computer-readable program code. The term "computer-readable program code" includes any type of computer code, including source code, object code, and executable code. The term "computer-readable medium" includes any type of medium that can be accessed by a computer, such as Read Only Memory (ROM), Random Access Memory (RAM), hard disk drive, Compact Disc (CD), Digital Video Disk (DVD), or other type of memory. A "non-transitory" computer-readable medium excludes wired, wireless, optical, or other communication links that transmit transient electrical or other signals. Non-transitory computer readable media includes media on which data is permanently stored, and media on which data is stored and subsequently overwritten, such as re-recordable optical disks or erasable memory devices.

[0016] Definitions of certain words and phrases are provided throughout this specification, and one of ordinary skill in the art should understand that in many cases, if not most cases, such definitions apply to previous and future uses of such defined words and phrases.

[0017] 1 to 7 described below, and various embodiments used in this specification to explain the principles of the present invention, are merely examples and should not be construed as limiting the scope of the present invention in any manner. Those skilled in the art will understand that the principles of the present invention may be embodied in any appropriately arranged system or device.

[0018] The following description with reference to the drawings is provided to aid in a comprehensive understanding of various embodiments of the present invention defined by the technical scope and its equivalents. Although various specific details are included herein to aid in understanding, they should be considered as examples only. Therefore, those skilled in the art will recognize that various changes and modifications of the various embodiments described herein are possible without departing from the technical scope and spirit of the present invention. Also, for clarity and conciseness, descriptions of well-known functions and configurations are omitted.

[0019] The terms and words used in the following description are not limited to their bibliographical meanings, but are used by the inventors for a clear and consistent understanding of the present invention. Therefore, it is obvious to those skilled in the art that the following description of various embodiments of the present invention is provided for illustrative purposes only, and does not limit the disclosure defined by the technical scope of the present invention and its equivalents.

[0020] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a "component surface" includes reference to one or more of such surfaces.

[0021] The term "substantially" means that the referenced property, parameter, or value need not be achieved exactly, but that deviations or variations, including, for example, tolerances, measurement errors, measurement accuracy limits, and other factors known to those of ordinary skill in the art, will occur in an amount that does not eliminate the effect that the property is intended to provide.

[0022] It is well known to those skilled in the art that the blocks of the flowcharts (or sequence diagrams) and combinations of flowcharts are represented and executed by computer program instructions. Such computer program instructions are loaded onto a processor of a general purpose computer, special purpose computer, or programmable data processing device. When the loaded program instructions are executed by the processor, they generate means for performing the functions described in the flowcharts. The computer program instructions can also be stored in a computer readable memory that can be used by the special purpose computer or programmable data processing device to generate an article of manufacture that performs the functions described in the flowcharts. When the computer program instructions are loaded into a computer or programmable data processing device and executed as a process, they perform the operations of the functions described in the flowcharts.

[0023] The blocks of the flowcharts may correspond to or be portions of modules, segments, or codes that include one or more executable instructions that embody one or more logical functions. In some cases, the functions described by the blocks may be performed in a different order than that recited. For example, two blocks recited in a sequence may be performed simultaneously or in the reverse order.

[0024] In this specification, the words "unit", "module", etc. refer to a software component or hardware component, such as a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC), that performs a function or operation. However, the "unit" etc. is not limited to hardware or software. The unit etc. may reside on an addressable storage medium or be configured to drive one or more processors. The unit etc. may further refer to a software component, an object-oriented software component, a class component, a task component, a process, a function, an attribute, a procedure, a subroutine, a program code segment, a driver, firmware, microcode, a circuit, data, a database, a data structure, a table, an array, or a variable. The functionality provided by the components and units may be a combination of smaller components and units, or may be combined with others to form larger components and units. The components and units may be configured to drive a device or one or more processors in a secure multimedia card.

[0025] Before describing the present invention in detail, terms and definitions necessary for understanding the present invention will be explained. However, such terms should be interpreted in a non-limiting manner.

[0026] A “base station (BS)” is an entity that communicates with a user equipment (UE) and may also be called a BS, a base transceiver station (BTS), a Node B (NB), an evolved NB (eNB), an access point (AP), a 5G NB (5GNB), or a next generation Node B (gNB).

[0027] "UE" is an entity that communicates with the BS and may also be referred to as a UE, device, mobile station (MS), mobile equipment (ME), or terminal.

[0028] FIG. 1 is a diagram illustrating the structure of a next-generation mobile communication system according to various embodiments of the present invention.

[0029] Referring to FIG. 1, the radio access network of the next-generation mobile communication system includes a next-generation base station 1-10 (hereinafter referred to as NR NB (new radio node B), gNodeB (next generation node B), or gNB) and an NR CN (new radio core network) 1-05 (or NG CN (next generation core network). A user equipment 1-15 (new radio user equipment) (hereinafter referred to as NR UE or UE) accesses an external network via the NR NB 1-10 and the NR CN 1-05.

[0030] In FIG. 1, NR NB1-10 corresponds to the eNB (evolved Node B) of the existing LTE system. The NR NB is connected to NR UE1-15 via a radio channel and provides better services than the existing Node B. In the next generation mobile communication system, all user traffic is served via a shared channel, so a device is required to collect and schedule state information such as the UE's buffer state, available transmission power state, and channel state, which is handled by the NR NB1-10. One NR NB generally controls multiple cells. The NR NB has a wider bandwidth than the existing maximum bandwidth to realize ultra-high speed data transmission compared to the existing LTE, and applies orthogonal frequency-division multiplexing (OFDM) through radio access technology and further applies beamforming technology. In addition, the adaptive modulation and coding (AMC) method is applied, which determines the modulation method and channel-coding rate according to the UE's channel state. The NR CN1-05 performs the functions of mobility support, bearer setup, and quality of service (QoS) setup. The NR CN is a device that performs various control functions as well as managing the mobility of UEs, and is connected to multiple eNBs. In addition, the next-generation mobile communication system works with the existing LTE system, and the NR CN is connected to MME1-25 via a network interface. The MME is connected to the existing base stations eNB1-30.

[0031] FIG. 2 is a diagram illustrating a radio protocol architecture of a next-generation mobile communication system according to various embodiments of the present invention.

[0032] Referring to FIG. 2, the radio protocols of the next-generation mobile communication system include NR SDAP (Service Data Adaptation Protocol) 2-01 and 2-45, NR PDCP 2-05 and 2-40, NR RLC 2-10 and 2-35, and NR MAC 2-15 and 2-30 in the UE and NR gNB.

[0033] Key features of the NR SDAP2-01 and 2-45 include some of the following:

[0034] -User data transmission function (user plane data transmission),

[0035] - QoS flow and data bearer mapping function for uplink and downlink (mapping between QoS flows and DRBs for both DL and UL);

[0036] QoS flow identifier (ID) display function for uplink and downlink (displaying QoS flow ID for both DL and UL packets); and

[0037] - Function for mapping reflective QoS flows for uplink SDAP PDUs to data bearers (mapping between reflective QoS flows for UL SDAP PDUs and DRBs).

[0038] For the SDAP layer device, the UE receives a configuration for each PDCP layer device, each bearer, or each logical channel via an RRC message, regarding whether to use the header of the SDAP layer device or the function of the SDAP layer device. If the SDAP header is configured, the 1-bit indicator of NAS reflective QoS and the 1-bit indicator of AS reflective QoS in the SDAP header indicate that the UE updates or reconfigures the information for the mapping of QoS flows and data bearers in the uplink and downlink. The SDAP header includes QoS flow ID information indicating the QoS. The QoS information is used as data processing priority or scheduling information to support seamless services.

[0039] The main functions of NR PDCP2-05 or 2-40 include some of the following functions:

[0040] -Header compression and decompression function (Header compression and decompression: ROHC only);

[0041] -User data transmission function (transmission of user data);

[0042] - sequential transmission function (in-sequence transmission of higher layer PDUs);

[0043] - Out-of-sequence transmission function (out-of-sequence transmission of higher layer PDUs);

[0044] -Reordering function (PDCP PDU reordering for reception);

[0045] - Duplication detection function (detection of duplication of lower layer SDU);

[0046] -Retransmission function (retransmission of PDCP SDUs);

[0047] -Encryption and decryption functions (encryption and decryption); and

[0048] - Timer-based SDU removal function (timer-based SDU discard in uplink).

[0049] The reordering function of the NR PDCP device is a function that sequentially reorders PDCP PDUs received at a lower layer based on the PDCP sequence number (SN), and includes functions to sequentially transmit the reordered data to a higher layer, to directly transmit the reordered data regardless of the procedure, to record PDCP PDUs lost due to reordering, to report the status of lost PDCP PDUs to the transmitting side, and to request retransmission of lost PDCP PDUs.

[0050] The main functions of the NR RLC2-10 or 2-35 include some of the following features:

[0051] - Data transmission function (transmission of higher layer PDUs);

[0052] - sequential transmission function (in-sequence transmission of higher layer PDUs);

[0053] - Out-of-sequence transmission function (out-of-sequence transmission of higher layer PDUs);

[0054] -ARQ function (error correction through ARQ);

[0055] - Joining, segmentation and reassembly functions (joining, segmentation and reassembly of RLC SDUs);

[0056] -Re-segmentation function (re-segmentation of RLC data PDUs);

[0057] - Reordering function (reordering of RLC data PDUs);

[0058] -Duplicate detection feature (Duplicate detection);

[0059] -Error detection function (protocol error detection);

[0060] -RLC SDU deletion function (RLC SDU discard); and

[0061] -RLC re-establishment function (RLC re-establishment).

[0062] The in-sequence delivery function of the NR RLC device is a function of sequentially delivering RLC PDUs received at a lower layer to a higher layer. This function includes a function of reassembling and transmitting RLC SDUs when one original RLC SDU is divided into multiple RLC SDUs and received, a function of reordering received RLC PDUs based on the RLC SN (sequence number) or PDCP SN, a function of recording RLC PDUs lost due to reordering, a function of reporting the status of a lost RLC PDU to the transmitting side, a function of requesting retransmission of a lost RLC PDU, a function of sequentially delivering only RLC SDUs up to the lost RLC SDU to a higher layer when a lost RLC SDU exists, a function of sequentially delivering all RLC SDUs received before the timer started to a higher layer when a predetermined timer expires even if there is a lost RLC SDU, or a function of sequentially delivering all RLC SDUs received up to that point to a higher layer when a predetermined timer expires even if there is a lost RLC SDU.

[0063] Also, the NR RLC device processes the RLC PDUs in the order in which they are received (by order of arrival, regardless of serial number or sequence number) and delivers the RLC PDUs to the PDCP device regardless of procedure (out-of-sequence delivery). In the case of segments, the NR RLC device receives buffered or later received segments, reassembles them into an RLC PDU, processes the RLC PDU, and then transmits it to the PDCP device. The NR RLC layer may not include a joining function, which is performed by the NR MAC layer or is replaced by the multiplexing function of the NR MAC layer.

[0064] The out-of-sequence delivery function of the NR RLC device is a function that directly delivers RLC SDUs received at a lower layer to a higher layer regardless of the procedure of the RLC SDU. This function includes a function to reassemble and transmit RLC PDUs when one original RLC SDU is received divided into multiple RLC SDUs, and a function to store the RLC SN or PDCP SN of the received RLC PDU, reorder the RLC PDUs, and record lost RLC PDUs.

[0065] The NR MAC 2-15 and 2-30 are connected to multiple NR RLC layer devices configured in one UE, and the main functions of the NR MAC include some of the following functions:

[0066] - Mapping function (mapping between logical channels and transmission channels);

[0067] - Multiplexing and demultiplexing functions (MAC SDU multiplexing / demultiplexing);

[0068] -Scheduling information reporting function (Scheduling information reporting);

[0069] -HARQ function (error correction through HARQ);

[0070] -Logical channel priority control function (priority handling between logical channels of one UE);

[0071] -UE priority control function (priority handling between UEs through dynamic scheduling),

[0072] -MBMS service identification function (MBMS service identification);

[0073] -Transmission format selection function (transmission format selection); and

[0074] -Padding function (padding).

[0075] The NR PHY layers 2-20 and 2-25 perform the operations of channel coding and modulating upper layer data to generate OFDM symbols, transmitting the OFDM symbols via a wireless channel, or demodulating and channel decoding the OFDM symbols received via the wireless channel, and transmitting the demodulated and channel decoded OFDM symbols to an upper layer.

[0076] FIG. 3 is a diagram illustrating an example of setting bandwidth portions in a wireless communication system according to various embodiments of the present invention.

[0077] 3, an example is shown in which a UE bandwidth 300 is configured with two BWPs, i.e., BWP#1 (301) and BWP#2 (302). The base station configures one or multiple BWPs for the UE and sets a series of information as shown in Table 1 below for each bandwidth portion.

[0078] [Table 1]

[0079] The embodiment of the present invention is not limited to the above example, and in addition to the configuration information, various parameters related to the BWP are configured in the UE, and some series of information are omitted. Such a series of information is transmitted from the base station to the UE via higher layer signaling, for example, RRC (radio resource control) signaling. At least one BWP among the configured one or more BWPs is activated. Whether or not to activate the configured BWP is semi-statically transmitted from the base station to the UE via RRC signaling or dynamically transmitted via DCI (Downlink Control Information).

[0080] According to some embodiments, an initial bandwidth portion (BWP) for initial access is configured from a base station via a master information block (MIB) to a UE before radio resource control (RRC) connection. More specifically, the UE receives configuration information for a search rate and a control resource set (CORESET) transmitted via the MIB in an initial access operation for a PDCCH for receiving system information (corresponding to remaining system information (RMSI) or system information block 1 (SIB 1)) required for initial access. The control resource set (CORESET) and search space configured via the MIB are each considered as identity (ID) 0. The base station notifies the UE of configuration information such as frequency allocation information, time allocation information, and numerology for the control resource set #0 via the MIB. In addition, the base station notifies the UE of configuration information for a monitoring period and occasion for the control resource set #0, i.e., configuration information for the search space #0, via the MIB. The UE considers the frequency domain configured as the control resource set #0 acquired from the MIB as an initial BWP for initial access. Here, the identifier (ID) of the initial BWP is considered to be 0.

[0081] The BWP configuration supported by 5G can be used for a variety of purposes.

[0082] According to some embodiments, the case where the bandwidth supported by the UE is smaller than the system bandwidth is supported through the BWP configuration. For example, the base station configures the frequency location of the BWP (configuration information 2) to the UE so that the UE transmits and receives data at a specific frequency location within the system bandwidth.

[0083] According to some embodiments, the base station configures multiple BWPs to the UE for the purpose of supporting different numeral radii. For example, to support both data transmission and reception with a predetermined UE using subcarrier spacing of 15 kHz and subcarrier spacing of 30 kHz, two BWPs are configured to use subcarrier spacing of 15 kHz and subcarrier spacing of 30 kHz, respectively. The different BWPs are frequency division multiplexed, and when data transmission and reception is attempted at a specific subcarrier spacing, the BWP configured at the specific subcarrier spacing is activated.

[0084] Also, according to some embodiments, the base station sets BWPs having different bandwidths to the UE in order to reduce the power consumption of the UE. For example, if the UE supports a very large bandwidth, for example, a bandwidth of 100 MHz, and always transmits and receives data in the bandwidth, such transmission or reception causes very high power consumption for the UE. In particular, if the UE monitors unnecessary downlink control channels with a large bandwidth of 100 MHz even when there is no traffic, such monitoring may be very inefficient in terms of power consumption. Therefore, the base station sets a BWP with a relatively small bandwidth, for example, a BWP of 20 MHz, to the UE in order to reduce the power consumption of the UE. In a situation where there is no traffic, the UE performs a monitoring operation with a BWP of 20 MHz. When data to be transmitted or received is generated, the UE transmits or receives data with a BWP of 100 MHz according to an instruction from the base station.

[0085] In the method of setting the BWP, a UE before RRC connection receives setting information for an initial bandwidth portion through a master information block (MIB) in an initial connection operation. More specifically, a control resource set (CORESET) for a downlink control channel in which downlink control information (DCI) for scheduling a system information block (SIB) is transmitted from a physical broadcast channel (PBCH) MIB is set in the UE. The bandwidth of the control resource set set through the MIB is considered as the initial BWP. The UE receives a physical downlink shared channel (PDSCH) through which the SIB is transmitted through the set initial BWP. The initial BWP is used not only for receiving the SIB but also for other system information (OSI), paging, and random access.

[0086] In recent years, many broadband wireless technologies have been developed to meet the increasing number of broadband subscribers and provide better applications and services. Second generation wireless communication systems were developed to provide voice services while ensuring user mobility. Third generation wireless communication systems support not only voice services but also data services. Recently, fourth generation wireless communication systems have been developed to provide high speed data services. However, currently, fourth generation wireless communication systems suffer from a lack of resources to meet the increasing demand for high speed data services. Therefore, fifth generation wireless communication systems (also known as Next Generation Wireless or NR) are being developed to meet the increasing demand for high speed data services and support ultra-reliable and low latency applications.

[0087] The 5th generation wireless communication system supports not only lower frequency bands but also higher frequency (mmWave) bands (e.g., 10 GHz to 100 GHz bands) to achieve higher data transmission rates. To mitigate radio wave propagation losses and increase transmission distances, beamforming, MIMO, FD-MIMO, array antennas, analog beamforming, and large antenna technologies are considered in the 5G wireless communication system design. The 5th generation wireless communication system is also expected to handle a variety of use cases with very different requirements in terms of data speed, latency, safety, mobility, etc. However, the design of the air interface of the 5th generation wireless communication system is expected to be flexible enough to serve UEs with very different capabilities depending on the use cases and market sectors in which the UE serves the end customers.

[0088] Some use cases that are expected to be addressed by the 5th generation wireless communication system radio system are eMBB, m-MTC, URLL, etc. eMBB requirements (e.g. data speeds of tens of Gbps, low latency, high mobility, etc.) address the market segment representing existing wireless broadband subscribers who need Internet connectivity anytime and anywhere. m-MTC requirements (e.g. very high connection density, intermittent data transmission, very long battery life, low mobility handling, etc.) address the market segment representing IoT / IoE which envisages the connection of billions of devices. URLL requirements (e.g. very low latency, very high reliability and variable mobility, etc.) address the market segment representing industrial automation applications, vehicle-to-vehicle / vehicle-to-infrastructure communication which is expected as one of the enablers for autonomous vehicles.

[0089] In 5G wireless communication systems operating in high frequency (e.g. mmWave) bands, UEs and gNBs communicate with each other using beamforming. Beamforming technology is used to mitigate propagation path loss and increase propagation distance for communication in high frequency bands. Beamforming improves transmission and reception performance using high gain antennas. Beamforming is classified into transmit (TX) beamforming performed at the transmitting end and receive (RX) beamforming performed at the receiving end. In general, TX beamforming uses multiple antennas to increase directivity by making the propagation reachable area densely located in a specific direction. In this case, the aggregation of multiple antennas is called an antenna array, and each antenna included in the array is called an array element. Antenna arrays are configured in various shapes such as linear arrays, planar arrays, etc. Using TX beamforming increases the directivity of the signal and increases the propagation distance.

[0090] Also, since the signal is hardly transmitted in a direction other than the directional direction, signal interference acting on other receiving ends is greatly reduced. The receiving end performs beamforming on the RX signal using an RX antenna array. RX beamforming provides the effect of blocking interference signals by increasing the strength of the RX signal transmitted in a specific direction by concentrating the propagation in a specific direction and removing signals transmitted in directions other than the specific direction from the RX signal. By using beamforming technology, the transmitter can create multiple transmission beam patterns in different directions. Each of these transmission beam patterns is called a TX beam. Wireless communication systems operating at high frequencies use multiple narrow TX beams to transmit signals in a cell, with each narrow TX beam providing coverage to a portion of the cell. The narrower the TX beam, the higher the antenna gain, and therefore the greater the propagation distance of the signal transmitted using beamforming. The receiver can further create multiple RX beam patterns in different directions. Each of these reception patterns is also called an RX beam.

[0091] CA / Multiple Access in 5G Wireless Communication Systems: The 5G wireless communication systems support dual connectivity (DC) and standalone operation modes. In DC, multiple Rx / Tx UEs are configured to utilize resources provided by two different nodes (or NBs) connected via a non-ideal backhaul. One node acts as a master node (MN) and the other node acts as a supplementary node (SN). The MN and SN are connected via a network interface, and at least the MN is connected to a core network. NR further supports multi-RAT dual connectivity (MR-DC) operation, in which an RRC_CONNECTED (radio resource control connected) UE is configured to use radio resources provided by two separate schedulers located in two different nodes connected via a non-ideal backhaul to provide E-UTRA (i.e., when the node is a ng-eNB) or NR access (i.e., when the node is a gNB).

[0092] In NR, for an RRC CONNECTED UE not configured with CA / DC, there is only one serving cell consisting of a primary cell. For an RRC_CONNECTED UE configured with CA / DC, the term 'serving cell' is used to refer to a cell set consisting of a special cell (SpCell) and all secondary cells (SCells). In NR, the term master cell group (MCG) refers to a serving cell group associated with a master node, including a primary cell (PCell) and optionally one or more secondary cells (SCells). In NR, the term secondary cell group (SCG) refers to a serving cell group associated with a secondary node, including a PCell and optionally one or more SCells. In NR, a primary cell (PCell) refers to a serving cell in an MCG operating on a primary frequency on which a UE performs an initial access establishment procedure or initiates an access re-establishment procedure.

[0093] In NR, for a UE configured for CA, an SCell is a cell that provides additional radio resources on a special cell. A Primary SCG Cell (PSCell) refers to a serving cell in an SCG to which a UE has random access when the UE reconfigures during a synchronization procedure. In case of dual connectivity operation, the term SpCell (i.e., special cell) refers to a PCell of an MCG or a PSCell of an SCG, otherwise the term special cell refers to a PCell.

[0094] UE States in 5G Wireless Communication System: In a 5G wireless communication system, the RRC may be in one of the following states: RRC_IDLE, RRC_INACTIVE, and RRC_CONNECTED. If an RRC connection is established, the UE is in RRC_CONNECTED state or in RRC_INACTIVE state. Otherwise, i.e., if an RRC connection is not established, the UE is in RRC_IDLE state. The RRC states are characterized as follows:

[0095] In RRC_IDLE, UE specific DRX is configured by higher layers. The UE monitors short messages sent to P-RNTI via DCI; monitors paging channels for CN paging using 5G-S-TMSI; performs neighbor cell measurements and cell selection; acquires system information and can send SI requests (if configured); logs available measurements along with location and time for logged measurement configured UEs.

[0096] In RRC_INACTIVE, UE specific DRX is configured by a higher layer or the RRC layer; the UE stores the UE inactive AS context; the RAN based notification area is configured by the RRC layer. The UE monitors short messages sent to the P-RNTI via the DCI; monitors the paging channel for CN paging using 5G-S-TMSI and RAN paging using the overall I-RNTI; performs neighbor cell measurements and cell selection; periodically performs RAN based notification area updates when moving outside the configured RAN based notification area; acquires system information and can send SI requests (if configured); logs available measurements along with location and time for logged measurement configured UEs.

[0097] In RRC_CONNECTED, the UE stores the AS context, and unicast data transmission with the UE takes place. The UE monitors short messages sent over the DCI to the P-RNTI (if configured); monitors the control channel associated with the shared data channel to determine if data has been scheduled for the UE; provides channel quality and feedback information; performs neighbor cell measurements and measurement reports; and acquires system information.

[0098] Downlink control in 5G wireless communication system: In a 4G wireless communication system, a Physical Downlink Control Channel (PDCCH) is used to schedule DL transmission of PDSCH and UL transmission of PUSCH, where the Downlink Control Information (DCI) of the PDCCH includes: a downlink allocation including at least modulation and coding format, resource allocation and hybrid-ARQ information for DL-SCH; an uplink scheduling grant including at least modulation and coding format, resource allocation and hybrid-ARQ information for UL-SCH.

[0099] Besides scheduling, the PDCCH is used to activate and deactivate PUSCH transmission configured using a configured grant; activate and deactivate PDSCH semi-persistent transmission; inform one or more UEs of slot format; inform one or more UEs of PRBs and OFDM symbols that the UE assumes not to transmit; transmit TPC commands for PUCCH and PUSCH; transmit one or more TPC commands for SRS transmission by one or more UEs; UE active bandwidth portion (BWP) switching; and initiate RA procedures. The UE monitors the PDCCH candidate set at configured monitoring occasions in one or more configured control resource sets (CORESETs) according to corresponding search space configurations. A CORESET includes a PRB set with a time duration of 1 to 3 OFDM symbols. Resource units Resource Element Group (REG) and Control Channel Elements (CCEs) are defined within a CORESET, where each CCE includes a REG set. A control channel is formed by aggregation of CCEs. Different code rates for the control channel are realized by aggregating different numbers of CCEs. Interleaved and non-interleaved CCE-REG mapping is supported in CORESET. Polar coding is used for the PDCCH. Each REG carrying the PDCCH carries its own DMRS. QPSK modulation is used for the PDCCH.

[0100] In a 5G wireless communication system, a list of search space configurations is signaled by the gNB for each configured BWP, where each search configuration is uniquely identified by an identifier. Identifiers of search space configurations used for specific purposes, such as paging reception, SI reception, and random access response reception, are explicitly signaled by the gNB. In NR, a search space configuration consists of the parameters monitoring-periodicity-PDCCH-slot, monitoring-offset-PDCCH-slot, monitoring-symbols-PDCCH-within-slot, and duration. The UE determines the PDCCH monitoring occasion within a slot using the parameters PDCCH monitoring period (monitoring-periodicity-PDCCH-slot), PDCCH monitoring offset (monitoring-offset-PDCCH-slot), and PDCCH monitoring pattern (monitoring-symbols-PDCCH-within-slot). A PDCCH monitoring occasion exists from slot “x” to x+duration, where slot with number “x” in radio frame with number “y” is given by:

[0101] (y*(number of slots in the radio frame)+x-Monitoring-offset-PDCCH-slot) mod (Monitoring-periodicity-PDCCH-slot)=0.

[0102] For each slot with a PDCCH monitoring occasion, the starting symbol of the PDCCH monitoring occasion is given by monitoring-symbols-PDCCH-within-slot. The length (in symbols) of the PDCCH monitoring occasion is provided in CORSET for the search space. The search space configuration includes an identifier of the CORESET configuration associated with the search space. A CORESET configuration list is signaled by the gNB for each configured BWP, where each CORESET configuration is uniquely identified by an identifier. Note that each radio frame has a duration of 10 ms. A radio frame is identified by a radio frame number or a system frame number. Each radio frame consists of a number of slots, where the number of slots in a radio frame and the duration of the slots vary depending on the subcarrier spacing. The number of slots in a radio frame and the duration of the slots are predefined in NR by the radio frame for each supported SCS. Each CORESET configuration is associated with a list of Transmission configuration indicator (TCI) states. One DL RS ID (SSB or CSI RS) is configured per TCI state. The TCI state list corresponding to the CORESET configuration is signaled by the gNB via RRC signaling. One of the TCI states in the TCI state list is activated and indicated by the gNB to the UE. The TCI state indicates the DL TX beam (the DL TX beam is QCL'd with the SSB / CSI RS of the TCI state) that the gNB uses for PDCCH transmission in the PDCCH monitoring occasion of the search space.

[0103] Bandwidth Part in 5G Wireless Communication System: In the fifth generation wireless communication system, bandwidth adaptation (BA) is supported. With BA, the reception and transmission bandwidth of the UE is adjusted so that it does not need to be as large as the bandwidth of the cell, its width is arranged to be changed (e.g., reduced during periods of low activity to save power), its location is moved in the frequency domain (e.g., for improved scheduling flexibility), and its subcarrier spacing (SCS) is arranged to be changed (e.g., to allow different services). A subset of the entire cell bandwidth of a cell is called a BWP. BA is achieved by configuring an RRC connected UE with a BWP and informing the UE which of the configured BWPs is the currently active BWP. When BA is configured, the UE only needs to monitor the PDCCH of one active BWP (i.e., the UE does not need to monitor the PDCCH on the entire DL frequency of the serving cell). In the RRC connected state, the UE is configured with one or more DL and UL BWPs for each configured serving cell (i.e., PCell or SCell).

[0104] For an activated serving cell, there is always one active UL and DL BWP at any time. BWP switching of the serving cell is used to activate an inactive BWP at a time and deactivate an active BWP. BWP switching is controlled by PDCCH indicating downlink assignment or uplink grant, bwp-InactivityTimer, RRC signaling, or by the MAC entity itself at the start of the random access procedure. At the time of SpCell addition or SCell activation, the DL BWP and UL BWP indicated by firstActiveDownlinkBWP-Id and firstActiveUplinkBWP-Id, respectively, are activated without receiving PDCCH indicating downlink assignment or uplink grant. The active BWP of the serving cell is indicated by RRC or PDCCH. In the case of unpaired spectrum, the DL BWP is paired with the UL BWP, and BWP switching is common to both UL and DL. When the BWP inactivity timer expires, the UE switches the active DL BWP to the default DL BWP or to the initial DL BWP (if the default DL BWP is not configured).

[0105] In RRC_IDLE and RRC_INACTIVE states, the UE receives downlink transmissions from the gNB in ​​an initial DL BWP and sends uplink transmissions in an initial UL BWP. The initial DL BWP configuration is signaled by the initialDownlinkBWP field in the system information (SIB1). The initial UL BWP configuration is signaled by the initialUplinkBWP field in the system information (SIB1).

[0106] Random Access in 5G Wireless Communication System: In the 5G wireless communication system, RA (Random Access) is supported. RA (Random Access) is used to achieve uplink (UL) time synchronization. RA is used during initial access, handover, radio resource control (RRC) connection re-establishment procedure, scheduling request transmission, secondary cell group (SCG) addition / modification, beam failure recovery, and data or control information transmission in UL by a UE that is not synchronized in the RRC connected state. Many types of random access procedures are supported.

[0107] Contention-Based Random Access (CBRA): This is also called 4-step CBRA. In this type of random access, the UE first transmits a random access preamble (also called Msg1) and then waits for a random access response (RAR) in the RAR window. The RAR is also called Msg2. The next-generation Node B (gNB) transmits the RAR on a physical downlink shared channel (PDSCH). The PDCCH that schedules the PDSCH carrying the RAR is addressed by the RA-radio network temporary identifier (RA-RNTI). The RA-RNTI identifies the time-frequency resource (also called a PRACH (physical RA channel) occasion or a PRACH transmission (TX) occasion or a RACH (RA channel) occasion) on which the RA preamble was detected by the gNB.

[0108] RA-RNTI is calculated as follows: RA-RNTI=1+s_id+14*t_id +14*80*f_id+14*80*8*ul_carrier_id, where s_id is the index of the first orthogonal frequency division multiplexing (OFDM) symbol of the PRACH occasion from which the UE transmitted Msg1, i.e., the RA preamble (0≦s_id<14); t_id is the index of the first slot of the PRACH occasion (0≦t_id<80); f_id is the index of the PRACH occasion within the slot in the frequency domain (0≦f_id<8), and ul_carrier_id is the UL carrier used for Msg1 transmission (0 for normal UL (NUL) carrier, 1 for supplementary UL (SUL) carrier). Many RARs for various random access preambles detected by the gNB are multiplexed in the same RAR MAC (media access control) protocol data unit (PDU) by the gNB. An RAR in the MAC PDU corresponds to a UE RA preamble transmission if the RA preamble identifier (RAID) of the UE transmitted RA preamble is included in the RAR. If an RAR corresponding to its own RA preamble transmission is not received during the RAR window and the UE has not yet transmitted an RA preamble for a configurable number of times (set by the gNB in ​​the RACH configuration), the UE returns to the first stage, i.e., selects a random access resource (preamble / RACH / occasion) and transmits an RA preamble. A backoff can also be applied before returning to the first stage.

[0109] When an RAR corresponding to an RA preamble transmission is received, the UE transmits a message 3 (Msg3) with the UL grant received in the RAR. Msg3 includes messages such as an RRC connection request, an RRC connection re-establishment request, an RRC handover confirmation, a scheduling request, an SI request, etc. Msg3 includes a UE identity (i.e., a Cell-Radio Network Temporary Identifier (C-RNTI) or a System Architecture Evolution (SAE)-Temporary Mobile Subscriber Identity (S-TMSI) or a random number). After transmitting Msg3, the UE starts a contention resolution timer. If the UE receives a PDCCH (Physical Downlink Control Channel) addressed to the C-RNTI included in Msg3 while the contention resolution timer is running, the contention resolution is considered successful, the contention resolution timer is stopped, and the RA procedure is completed. If the UE receives a contention resolution MAC Control Element (CE) containing the UE's contention resolution identity (the first X bits of the Common Control Channel (CCCH) Service Data Unit (SDU) transmitted in Msg3) while the contention resolution timer is running, the contention resolution is considered successful, the contention resolution timer is stopped and the RA procedure is completed. If the contention resolution timer expires and the UE has not yet transmitted an RA preamble for a configurable number of times, the UE returns to phase 1, i.e. selects a random access resource (preamble / RACH occasion) and transmits an RA preamble. A backoff may also be applied before returning to phase 1.

[0110] Non-Contention Random Access (CFRA): This is also called legacy CFRA or 4-step CFRA. The CFRA procedure is used in scenarios such as handovers that require low latency, timing advance establishment of a secondary cell (Scell), etc. The evolved node B (eNB) assigns a dedicated random access preamble to the UE. The UE transmits a dedicated RA preamble. The eNB transmits an RAR on a PDSCH addressed to the RA-RNTI. The RAR carries an RA preamble identifier and timing alignment information. The RAR includes a UL grant. The RAR is transmitted in a RAR window similar to the contention based RA (CBRA) procedure. CFRA is considered to be successfully completed after receiving an RAR that includes the RA preamble identifier (RAID) of the RA preamble transmitted by the UE. If an RA is initiated for beam failure recovery, CFRA is considered to be successfully completed if a PDCCH addressed to the C-RNTI is received in the search space for beam failure recovery. If the RAR window expires and the RA is not completed successfully and the UE has not yet transmitted the RA preamble for a configurable number of times (configured by the gNB in ​​the RACH configuration), the UE retransmits the RA preamble.

[0111] In certain events such as handover and beam failure recovery, if a dedicated preamble is assigned to the UE, during the first stage of RA, i.e., during RA resource selection for Msg1 transmission, the UE decides whether to transmit a dedicated preamble or a non-dedicated preamble. The dedicated preamble is generally provided for a subset of SSB / CSI-RS. If there is no SSB / CSI-RS with DL RSRP higher than a threshold among the SSB / CSI-RS with non-contention random access resources (i.e., dedicated preamble / RO) provided by the gNB, the UE selects a preamble for vision. Otherwise, the UE selects a dedicated preamble. Thus, during the RA procedure, one random access attempt will be CFRA and the other random access attempt will be CBRA.

[0112] Two-Step Contention-Based Random Access (Two-Step CBRA): In the first step, the UE transmits a random access preamble over the PRACH and transmits a payload (i.e., MAC PDU) over the PUSCH. The random access preamble and payload transmission are also referred to as MsgA. In the second step, after transmitting MsgA, the UE monitors the response of the network (i.e., gNB) within a configured window. This response is also referred to as MsgB. The next-generation Node B (gNB) transmits MsgB over a physical downlink shared channel (PDSCH). The PDCCH that schedules the PDSCH carrying MsgB is addressed to the MsgB-radio network temporary identifier (MSGB-RNTI). The MSGB-RNTI identifies the time-frequency resource (also referred to as a PRACH (physical RA channel) occasion or a PRACH transmission (TX) occasion or a RACH (RA channel) occasion) on which the RA preamble was detected by the gNB. MSGB-RNTI is calculated as follows: RA-RNTI=1+s_id+14*t_id+14*80*f_id+14*80*8*ul_carrier_id+14X80X8X2, where s_id is the index of the first OFDM symbol of the PRACH occasion from which the UE transmitted Msg1, i.e., the RA preamble (0≦s_id<14); t_id is the index of the first slot of the PRACH occasion (0≦t_id<80); f_id is the index of the PRACH occasion within the slot in the frequency domain (0≦f_id<8), and ul_carrier_id is the UL carrier used for Msg1 transmission (0 for NUL (normal UL) carrier, 1 for SUL (supplementary UL) carrier).

[0113] If the CCCH SDU is transmitted in the MsgA payload, the UE performs contention resolution using the contention resolution information of MsgB. If the contention resolution identity received in MsgB matches the first 48 bits of the CCCH SDU transmitted in MsgA, contention resolution is successful. If the C-RNTI is transmitted in the MsgA payload, contention resolution is successful if the UE receives a PDCCH addressed to the C-RNTI. If contention resolution is successful, the random access procedure is deemed to have been completed successfully. Instead of contention resolution information corresponding to the transmitted MsgA, MsgB includes fallback information corresponding to the random access preamble transmitted in MsgA. If fallback information is received, the UE transmits Msg3 as in the CBRA procedure and performs contention resolution using Msg4. If contention resolution is successful, the random access procedure is deemed to have been completed successfully. If contention resolution fails during fallback (i.e., during transmission of Msg3), the UE retransmits MsgA. If the UE fails to receive MsgB including the contention resolution information or fallback information as described above due to the expiration of a configuration window during which the UE monitors the network response after transmitting MsgA, the UE retransmits MsgA. If the random access procedure is not successfully completed after transmitting MsgA a configurable number of times, the UE falls back to the 4-step RACH procedure, i.e., the UE transmits only the PRACH preamble.

[0114] The MsgA payload includes one or more of CCCH SDU, Dedicated Control Channel (DCCH) SDU, Dedicated Traffic Channel (DTCH) SDU, Buffer Status Report (BSR) MAC Control Element (CE), Power Headroom Report (PHR) MAC CE, SSB information, C-RNTI MAC CE, or padding. MsgA includes a UE ID (e.g., Random ID, S-TMSI, C-RNTI, Restart ID, etc.) along with a preamble in the first stage. The UE ID is included in the MAC PDU of MsgA. The UE ID, such as C-RNTI, is conveyed from the MAC CE, where the MAC CE is included in the MAC PDU. Other UE IDs (e.g., Random ID, S-TMSI, C-RNTI, Restart ID, etc.) are conveyed from the CCCH SDU. The UE ID may be one of Random ID, S-TMSI, C-RNTI, Restart ID, IMSI, Idle Mode ID, Inactive Mode ID, etc. The UE ID is different from each other in different scenarios where the UE performs the RA procedure.

[0115] When the UE performs RA after powering on (before the UE is connected to the network), the UE ID is a random ID. When the UE performs RA in idle state after the UE is connected to the network, the UE ID is an S-TMSI. When the UE has an assigned C-RNTI (e.g., the UE is in connected state), the UE ID is a C-RNTI. When the UE is in inactive state, the UE ID is a resumed ID. In addition to the UE ID, some additional control information is sent in MsgA. The control information is included in the MAC PDU of MsgA. The control information includes one or more of a connection request indication, a connection resume request indication, an SI request indication, a buffer status indication, beam information (e.g., one or more DL TX beam IDs or SSB IDs), a beam failure recovery indication / information, a data indicator, a cell / BS / TRP switching indication, a connection re-establishment indication, a reconfiguration complete or handover complete message, etc.

[0116] Two-Step Non-Contention Random Access (Two-Step CFRA): In this case, the gNB assigns the UE a dedicated random access preamble and PUSCH resources for MsgA transmission. The RO to be used for preamble transmission is also indicated. In the first stage, the UE transmits the random access preamble on PRACH and the payload on PUSCH using the non-contention random access resource (i.e., dedicated preamble / PUSCH resource / RO). In the second stage, after transmitting MsgA, the UE monitors the response of the network (i.e., gNB) within a configured window. This response is also called MsgB.

[0117] A next-generation Node B (gNB) transmits the RAR on a physical downlink shared channel (PDSCH). The PDCCH that schedules the PDSCH carrying the MsgB is addressed to the MsgB-radio network temporary identifier (MSGB-RNTI). The MSGB-RNTI identifies the time-frequency resource (also called the physical RA channel (PRACH) occasion or the PRACH transmission (TX) occasion or the RA channel (RACH) occasion) on which the RA preamble was detected by the gNB. MSGB-RNTI is calculated as follows: RA-RNTI=1+s_id+14*t_id+14*80*f_id+14*80*8*ul_carrier_id+14X80X8X2, where s_id is the index of the first OFDM symbol of the PRACH occasion from which the UE transmitted Msg1, i.e., the RA preamble (0≦s_id<14); t_id is the index of the first slot of the PRACH occasion (0≦t_id<80); f_id is the index of the PRACH occasion within the slot in the frequency domain (0≦f_id<8), and ul_carrier_id is the UL carrier used for Msg1 transmission (0 for NUL (normal UL) carrier, 1 for SUL (supplementary UL) carrier).

[0118] If the UE receives a PDCCH addressed to the C-RNTI, the random access procedure is deemed to be successfully completed. If the UE receives fallback information corresponding to the preamble transmitted by the UE, the random access procedure is deemed to be successfully completed.

[0119] When a dedicated preamble and PUSCH resource are assigned to the UE for a specific event, etc., in the case of handover and beam failure recovery, during the first stage of random access, i.e., during random access resource selection for MsgA transmission, the UE decides whether to transmit a dedicated preamble or a non-dedicated preamble. The dedicated preamble is generally provided for a subset of SSB / CSI-RS. If there is no SSB / CSI RS with DL RSRP higher than a threshold among the SSB / CSI-RS with non-contention random access resources (i.e., dedicated preamble / RO / PUSCH resources) provided by the gNB, the UE selects a preamble for vision. Otherwise, the UE selects a dedicated preamble. Thus, during the RA procedure, one random access attempt will be a two-step CFRA and the other random access attempt will be a two-step CBRA.

[0120] When the random access procedure is initiated, the UE first selects a carrier (SUL or NUL). If the carrier to be used for the random access procedure is explicitly signaled by the gNB, the UE selects the signaled carrier to perform the random access procedure. If the carrier to be used for the random access procedure is not explicitly signaled by the gNB, and if the serving cell for the random access procedure is configured in the auxiliary uplink and the RSRP of the downlink path loss criterion is smaller than rsrp-ThresholdSSB-SUL, the UE selects the SUL carrier to perform the random access procedure. Otherwise, the UE selects the NUL carrier to perform the random access procedure. After selecting the UL carrier, the UE determines the UL and DL BWP for the random access procedure as specified in section 5.15 of TS38.321. The UE then determines whether to perform a 2-step RACH or a 4-step RACH for this random access procedure as shown below.

[0121] - If this random access procedure is initiated by a PDCCH command and the ra-PreambleIndex explicitly provided by the PDCCH is not 0b000000, the UE selects a 4-step RACH.

[0122] -If a two-step non-contention random access resource is otherwise signaled by the gNB for this random access procedure, the UE selects a two-step RACH.

[0123] -If a 4-step non-contention random access resource is otherwise signaled by the gNB for this random access procedure, the UE selects a 4-step RACH.

[0124] Otherwise, if the UL BWP selected for this random access procedure is configured with only two-step RACH resources, the UE selects the two-step RACH.

[0125] Otherwise, if the UL BWP selected for this random access procedure is configured with only 4-step RACH resources, the UE selects the 4-step RACH.

[0126] - Otherwise, if the UL BWP selected for this random access procedure is configured with both 2-step and 4-step RACH resources,

[0127] If the RSRP of the downlink path loss criterion is less than the configured threshold, the UE selects the 4-step RACH; otherwise, the UE selects the 2-step RACH.

[0128] If a random access procedure is initiated in the serving cell, after selecting a carrier for the random access procedure, the MAC entity performs the following for the selected carrier of this serving cell:

[0129] *1> If no PRACH occasion is set for an active UL BWP:

[0130] **2> Switch the active UL BWP to the BWP indicated by the initialUplinkBWP;

[0131] **2>If the serving cell is SpCell:

[0132] ***3>Switch the active DL BWP to the BWP indicated by the initialDownlinkBWP.

[0133] *1>If not:

[0134] **2>If the serving cell is SpCell:

[0135] ***3> If the active DL BWP does not have the same bwp-Id as the active UL BWP:

[0136] ****4>Switch the active DL BWP to a DL BWP that has the same bwp-Id as the active UL BWP.

[0137] *1>If defaultDownlinkBWP-Id is set and the active DL BWP is not the BWP indicated by defaultDownlinkBWP-Id and the active DL BWP is not the BWP indicated by dormantBWP-Id (if set); or

[0138] *1>If defaultDownlinkBWP-Id is not set, the active DL BWP is not the initialDownlinkBWP, and the active DL BWP is not the BWP indicated by dormantBWP-Id (if set):

[0139] **2> When the bwp-InactivityTimer associated with an active DL BWP expires:

[0140] ***3>If defaultDownlinkBWP-Id is set:

[0141] ****4>Perform BWP switching to the BWP specified in defaultDownlinkBWP-Id.

[0142] ***3>If not:

[0143] ****4>Perform BWP switching to initialDownlinkBWP.

[0144] In the current design, one initial uplink BWP and one initial downlink BWP are configured in a cell. There is one initial ULBWP in the uplink carrier of the serving cell. There is one initial downlink BWP in the downlink carrier of the serving cell. To support RedCap (reduced capability) UE, an additional initial uplink BWP is configured in the uplink carrier of the serving cell, and an additional downlink BWP is configured in the downlink carrier of the serving cell. When two initial uplink BWPs and two initial downlink BWPs are configured in one cell, how to handle the BWP operation becomes an issue. If the RACH occasion is not configured as an active UL BWP or the bwp-InactivityTimer expires, the UE switches to one of the two initial uplink BWPs.

[0145] FIG. 4 illustrates an example of BWP switching when a random access procedure is initiated according to various embodiments of the present invention.

[0146] In one embodiment of the present invention, a UE is configured with a first and / or second initial UL BWP on a NUL carrier. A UE is configured with a first and / or second initial UL BWP on a SUL carrier. A UE is configured with a first and / or second initial DL BWP. The first initial UL BWP and the first initial DL BWP of a carrier are for a non-RedCap UE. The second initial UL and the second initial DL BWP of a carrier are for a RedCap UE. A RedCap (reduced capability) UE is a UE that supports a reduced number of UE RX / TX antennas, a reduced bandwidth, a relaxed UE processing time, a relaxed UE processing capability, a reduced maximum number of DL MIMO layers, a relaxed maximum modulation order, a relaxed duplex operation, etc. The first initial UL BWP is indicated by an initialUplinkBWP field in an RRCReconfiguration message or system information. The second initial UL BWP is indicated by an initialUplinkBWPRedcap field in an RRCReconfiguration message or system information. The second initial UL BWP may be indicated by another name. The first initial DL BWP is indicated by the initialDownlinkBWP field in the RRC Reconfiguration message or the system information, and the second initial DL BWP is indicated by the initialDownlinkBWPRedcap field in the RRC Reconfiguration message or the system information.

[0147] If a random access procedure is initiated in the serving cell, after the selection of the carrier for performing the random access procedure, the MAC entity UE performs the following actions for the selected carrier of this serving cell:

[0148] *1> If no PRACH occasion is set for an active UL BWP:

[0149] **2>If the UE is in RedCap and initialUplinkBWPRedcap (i.e., the second initial UL BWP) is configured:

[0150] ***3> Switch the active UL BWP to the BWP indicated by initialUplinkBWPRedcap (i.e., switch the active UL BWP to the second initial UL BWP);

[0151] **2> Otherwise (i.e. UE is not redcap or UE is redcap but initialUplinkBWPRedcap is not set):

[0152] ***3> Switch the active UL BWP to the BWP indicated by initialUplinkBWP (i.e., switch the active UL BWP to the first initial UL BWP);

[0153] **2>If the serving cell is SpCell:

[0154] ***3>If the UE is RedCap and initialDownlinkBWPRedcap (i.e., second initial DL BWP) is configured:

[0155] ****4>Switch the active DL BWP to the BWP indicated by initialDownlinkBWPRedcap (i.e., switch the active DL BWP to the second initial DL BWP);

[0156] ***3> Otherwise (i.e. UE is not redcap or UE is redcap but initialDownlinkBWPRedcap is not set):

[0157] ****4> Switch the active DL BWP to the BWP indicated by initialDownlinkBWP (i.e., switch the active DL BWP to the first initial UL BWP).

[0158] Referring to FIG. 4, in operation 400, the UE identifies that a random access procedure has been initiated in a serving cell. In operation 402, the UE selects an uplink carrier for the serving cell. The selected UL carrier may be NUL or SUL. In operation 404, the UE identifies that no PRACH occasion is configured in an active UL BWP of the selected UL carrier for the serving cell. In operation 406, the UE identifies whether it is a redcap UE and / or whether an initial uplink BWP (e.g., initialUplinkBWPRedcap) for the redcap UE is configured.

[0159] Alternatively, in operation 406, the UE is a redcap UE and the UE identifies whether initialUplinkBWPRedcap is configured. If the UE is a redcap UE and initialUplinkBWPRedcap is configured, the UE switches the active UL BWP to the BWP indicated by initialUplinkBWPRedcap in operation 408. If the UE is not a redcap UE or is a redcap UE but initialUplinkBWPRedcap is not configured, the UE switches the active UL BWP to the BWP indicated by initialUplinkBWP in operation 410. In operation 412, the UE identifies whether the serving cell is a SpCell. If the serving cell is a SpCell, the UE identifies in operation 414 whether the UE is a redcap UE and / or whether an initial downlink BWP (e.g., initialDownlinkBWPRedcap) for the redcap UE is configured.

[0160] Alternatively, in operation 414, the UE is a redcap UE and the UE identifies whether initialDownlinkBWPRedcap is set. If the UE is a redcap UE and initialDownlinkBWPRedcap is set, the UE switches the active DL BWP to the BWP indicated by initialDownlinkBWPRedcap in operation 416. If the UE is not a redcap UE or is a redcap UE but initialDownlinkBWPRedcap is not set, the UE switches the active DL BWP to the BWP indicated by initialDownlinkBWP in operation 418. In operation 420, the UE performs a random access procedure using the active UL and DL BWPs. If the serving cell is not a SpCell (i.e., the serving cell is a SCell), the UE performs a random access procedure in operation 420 using the active UL and DL BWPs without switching the DL BWP.

[0161] FIG. 5 illustrates an example of BWP switching when a BWP inactivity timer expires according to various embodiments of the present invention.

[0162] In one embodiment of the present invention, a UE is configured with a first and / or second initial UL BWP on a NUL carrier. A UE is configured with a first and / or second initial UL BWP on a SUL carrier. A UE is configured with a first and / or second initial DL BWP. The first initial UL BWP and the first initial DL BWP of a carrier are for non-RedCap UEs. The second initial UL and the second initial DL BWP of a carrier are for RedCap UEs. A RedCap UE is a UE that supports a reduced number of UE RX / TX antennas, a reduced bandwidth, a relaxed UE processing time, a relaxed UE processing capability, a reduced maximum number of DL MIMO layers, a relaxed maximum modulation order, a relaxed duplex operation, etc. The first initial UL BWP is indicated by an initialUplinkBWP field in an RRCReconfiguration message or system information. The second initial UL BWP is indicated by an initialUplinkBWPRedcap field in an RRCReconfiguration message or system information. The second initial UL BWP is indicated by a different name. The first initial DL BWP is indicated by the initialDownlinkBWP field in the RRC Reconfiguration message or the system information, and the second initial DL BWP is indicated by the initialDownlinkBWPRedcap field in the RRC Reconfiguration message or the system information.

[0163] The UE action for each activated serving cell set in the bwp-InactivityTimer is as follows:

[0164] *1>If defaultDownlinkBWP-Id is set and the active DL BWP is not the BWP indicated by defaultDownlinkBWP-Id and the active DL BWP is not the BWP indicated by dormantBWP-Id (if set); or

[0165] *1> The UE is not a redcap UE, the defaultDownlinkBWP-Id is not configured, the active DL BWP is not the initialDownlinkBWP (i.e., the first initial DL BWP), and the active DL BWP is not the BWP indicated by the dormantBWP-Id (if configured); or

[0166] *1> If the UE is RedCap and defaultDownlinkBWP-Id is not configured, initialDownlinkBWPRedcap (i.e., the second initial DL BWP) is configured and the active DL BWP is not initialDownlinkBWPRedcap (i.e., the second initial DL BWP), and the active DL BWP is not the BWP indicated by dormantBWP-Id (if configured) (the UE checks whether the active DL BWP is not the BWP indicated by dormantBWP-Id only if dormantBWP-Id is configured for the serving cell; note that if dormantBWP-Id is not configured for the redcap UE, the redcap UE may not perform this check); or

[0167] *1> If the UE is RedCap and defaultDownlinkBWP-Id is not configured, initialDownlinkBWPRedcap (i.e., the second initial DL BWP) is not configured, the active DL BWP is not the initialDownlinkBWP (i.e., the first initial DL BWP), and the active DL BWP is not the BWP indicated by dormantBWP-Id (if configured) (the UE checks whether the active DL BWP is not the BWP indicated by dormantBWP-Id only if dormantBWP-Id is configured for the serving cell; note that if dormantBWP-Id is not configured for the redcap UE, the redcap UE may not perform this check):

[0168] **2> If a PDCCH addressed to a C-RNTI or CS-RNTI indicating a downlink assignment or uplink grant for an active BWP is received; or

[0169] **2> If a PDCCH addressed to a C-RNTI or CS-RNTI indicating a downlink assignment or uplink grant for an active BWP is received; or

[0170] **2> If a MAC PDU is sent with a configured uplink grant and no LBT failure indication is received from the lower layer; or

[0171] **2>If a MAC PDU is received with a configured downlink allocation:

[0172] ***3> if there is no ongoing random access procedure associated with this serving cell; or

[0173] ***3> If an ongoing random access procedure associated with this serving cell upon reception of such a PDCCH addressed to C-RNTI is successfully completed:

[0174] ****4>Start or restart the bwp-InactivityTimer associated with the active DL BWP:

[0175] **2> If the bwp-InactivityTimer associated with an active DL BWP expires:

[0176] ***3>If defaultDownlinkBWP-Id is set:

[0177] ****4>Perform BWP switching to the BWP indicated by defaultDownlinkBWP-Id.

[0178] ***3>Otherwise:

[0179] ****4>If the UE is a RedCap UE and initialDownlinkBWPRedcap (i.e., the second initial DL BWP) is configured:

[0180] *****5>Perform BWP switching to the BWP indicated by initialDownlinkBWPRedcap (i.e., the second initial DL BWP);

[0181] ****4>Otherwise (i.e. UE is not redcap or UE is redcap but initialDownlinkBWPRedcap is not set):

[0182] *****5>Perform BWP switching to the BWP indicated by initialDownlinkBWP (i.e., the first initial DL BWP).

[0183] At least one of bwp-InactivityTimer, defaultDownlinkBWP-Id, dormantBWP-Id, initialDownlinkBWP and initialDownlinkBWPRedcap is signaled by a base station (e.g., a gNB) in an RRCReconfiguration message or system information.

[0184] Referring to FIG. 5, in operation 500, the UE identifies that a bwp-InactivityTimer associated with an active DL BWP has expired. In operation 502, the UE identifies whether a defaultDownlinkBWP-Id is set. If the defaultDownlinkBWP-Id is set, the UE performs BWP switching to the BWP indicated by the defaultDownlinkBWP-Id in operation 504. If the defaultDownlinkBWP-Id is not set, the UE identifies whether the UE is a redcap UE and / or whether an initial downlink BWP (e.g., initialDownlinkBWPRedcap) for the redcap UE is set in operation 506. Alternatively, in operation 506, the UE is a redcap UE and the UE identifies whether an initialDownlinkBWPRedcap is set. If the UE is a redcap UE and the initialDownlinkBWPRedcap is set, the UE performs BWP switching to the BWP indicated by the initialDownlinkBWPRedcap in operation 508. If the UE is not a redcap UE, or is a redcap UE but initialDownlinkBWPRedcap is not set, the UE performs BWP switching to the BWP indicated by initialDownlinkBWP in operation 510 .

[0185] It should be noted that the above examples of Figures 4 and 5 are combined. For example, the UE can apply the example of Figure 4 when a random access procedure is initiated, and then apply the example of Figure 5 when the BWP inactivity timer expires after the random access procedure is completed.

[0186] In one embodiment of the present invention, a UE is configured with a first and / or second initial UL BWP on a NUL carrier. A UE is configured with a first and / or second initial UL BWP on a SUL carrier. A UE is configured with a first and / or second initial DL BWP. The first initial UL BWP and the first initial DL BWP of a carrier are for non-RedCap UEs. The second initial UL and the second initial DL BWP of a carrier are for RedCap UEs. A RedCap UE is a UE that supports a reduced number of UE RX / TX antennas, a reduced bandwidth, relaxed UE processing time, relaxed UE processing capability, a reduced maximum number of DL MIMO layers, a relaxed maximum modulation order, relaxed duplex operation, etc. The first initial UL BWP is indicated by an initialUplinkBWP field in an RRCReconfiguration message or system information. The second initial UL BWP is indicated by an initialUplinkBWPRedcap field in an RRCReconfiguration message or system information. The second initial UL BWP is indicated by another name. The first initial DL BWP is indicated by an initialDownlinkBWP field in an RRC Reconfiguration message or system information, and the second initial DL BWP is indicated by an initialDownlinkBWPRedcap field in an RRC Reconfiguration message or system information.

[0187] The UE receives the firstActiveDownlinkBWP-Id in the configuration of one or more serving cells in the RRCReconfiguration message. If the firstActiveDownlinkBWP-Id is configured for the SpCell, this field contains the ID of the DL BWP to be activated when performing RRC (re)configuration.

[0188] If firstActiveDownlinkBWP-Id is configured for a SCell, this field contains the ID of the downlink bandwidth portion used when the SCell is activated. The initial bandwidth portion is applied with BWP-Id=0.

[0189] If the firstActiveDownlinkBWP-Id for the serving cell is configured as 0, the UE determines the DL BWP to be activated when performing RRC (re)configuration if the serving cell is an SpCell, or the downlink bandwidth portion to be used when activating the SCell if the serving cell is an SCell, as follows:

[0190] - If the UE is a redcap UE and initialDownlinkBWPRedcap (i.e. 2nd initial DL BWP) is configured:

[0191] ■ The firstActiveDownlinkBWP-Id set to 0 indicates the initialDownlinkBWPRedcap (i.e., the second initial DL BWP),

[0192] - Otherwise

[0193] ■ The firstActiveDownlinkBWP-Id set to 0 indicates the initialDownlinkBWP (ie, the first initial DL BWP).

[0194] If the firstActiveUplinkBWP-Id is configured as 0 for the serving cell, the UE determines the UL BWP to be activated when performing RRC (re)configuration if the serving cell is an SpCell, or the uplink bandwidth portion to be used when activating the SCell if the serving cell is an SCell, as follows:

[0195] - If the UE is a redcap UE and initialUplinkBWPRedcap (i.e. 2nd initial UL BWP) is configured:

[0196] ■ Does the firstActiveUplinkBWP-Id set to 0 indicate the initialUplinkBWPRedcap (i.e., the second initial UL BWP)?

[0197] - Otherwise

[0198] ■ The firstActiveUplinkBWP-Id set to 0 indicates the initialUplinkBWP (ie, the first initial UL BWP).

[0199] *1> When the SCell is set to sCellState that is set to be activated at SCell configuration time, or a SCell activation / deactivation MAC CE that activates the SCell is received:

[0200] **2> If the SCell is deactivated before receiving the SCell activation / deactivation MAC CE; or

[0201] **2> If an SCell is configured with sCellState set to be activated when the SCell is configured:

[0202] ***3>Activate the SCell.

[0203] In one embodiment of the present invention, a UE is configured with a first and / or second initial UL BWP on a NUL carrier. A UE is configured with a first and / or second initial UL BWP on a SUL carrier. A UE is configured with a first and / or second initial DL BWP. The first initial UL BWP and the first initial DL BWP of a carrier are for non-RedCap UEs. The second initial UL and the second initial DL BWP of a carrier are for RedCap UEs. A RedCap UE is a UE that supports a reduced number of UE RX / TX antennas, a reduced bandwidth, relaxed UE processing time, relaxed UE processing capability, a reduced maximum number of DL MIMO layers, a relaxed maximum modulation order, relaxed duplex operation, etc. The first initial UL BWP is indicated by an initialUplinkBWP field in an RRCReconfiguration message or system information. The second initial UL BWP is indicated by an initialUplinkBWPRedcap field in an RRCReconfiguration message or system information. The second initial UL BWP is indicated by a different name. The first initial DL BWP is indicated by an initialDownlinkBWP field in an RRC Reconfiguration message or system information, and the second initial DL BWP is indicated by an initialDownlinkBWPRedcap field in an RRC Reconfiguration message or system information.

[0204] The UE is in RRC_CONNECTED state.

[0205] The UE receives an RRCReconfiguration message from the gNB.

[0206] The RRC reconfiguration message includes the configuration of the SCell.

[0207] -SCell settings include firstActiveUplinkBWP-Id and firstActiveDownlinkBWP-Id.

[0208] -firstActiveUplinkBWP-Id is set to 0.

[0209] -firstActiveDownlinkBWP-Id is set to 0.

[0210] -sCellState is set to be activated by the SCell setting.

[0211] When receiving a SCell configuration with sCellState set to Activated:

[0212] - The UE activates the SCell.

[0213] - if the UE is a redcap UE and initialUplinkBWPRedcap (i.e. the second initial UL BWP) is configured for this SCell:

[0214] ■ firstActiveUplinkBWP-Id set to 0 indicates initialUplinkBWPRedcap (i.e., the second initial UL BWP);

[0215] ■ The UE uses the BWP indicated by initialUplinkBWPRedcap (i.e., the second initial UL BWP) when activating the SCell (i.e., activates the BWP);

[0216] - otherwise (i.e., the UE is not a redcap UE or the UE is a redcap UE but initialUplinkBWPRedcap (i.e., the second initial UL BWP) is not configured);

[0217] ■ firstActiveUplinkBWP-Id set to 0 indicates the initialUplinkBWP (i.e., the first initial UL BWP);

[0218] ■ The UE uses the BWP indicated by the initialUplinkBWP (i.e., the first initial UL BWP) when activating the SCell (i.e., activates the BWP);

[0219] - If the UE is a redcap UE and initialDownlinkBWPRedcap (i.e. the second initial DL BWP) is configured for this SCell:

[0220] ■ firstActiveDownlinkBWP-Id set to 0 indicates initialDownlinkBWPRedcap (i.e., the second initial DL BWP);

[0221] ■ The UE uses the BWP indicated by initialDownlinkBWPRedcap (i.e., the second initial DL BWP) when activating the SCell (i.e., activates the BWP);

[0222] Otherwise (i.e. the UE is not a redcap UE or the UE is a redcap UE but initialDownlinkBWPRedcap (i.e. the second initial DL BWP) is not configured):

[0223] ■ firstActiveDownlinkBWP-Id set to 0 indicates the initialDownlinkBWP (i.e., the first initial DL BWP);

[0224] ■The UE uses the BWP (i.e., activates the BWP) indicated by the initialDownlinkBWP (i.e., the first initial DL BWP) when activating the SCell.

[0225] In one embodiment of the present invention, a UE is configured with a first and / or second initial UL BWP on a NUL carrier. A UE is configured with a first and / or second initial UL BWP on a SUL carrier. A UE is configured with a first and / or second initial DL BWP. The first initial UL BWP and the first initial DL BWP of a carrier are for non-RedCap UEs. The second initial UL and the second initial DL BWP of a carrier are for RedCap UEs. A RedCap UE is a UE that supports a reduced number of UE RX / TX antennas, a reduced bandwidth, relaxed UE processing time, relaxed UE processing capability, a reduced maximum number of DL MIMO layers, a relaxed maximum modulation order, relaxed duplex operation, etc. The first initial UL BWP is indicated by an initialUplinkBWP field in an RRCReconfiguration message or system information. The second initial UL BWP is indicated by an initialUplinkBWPRedcap field in an RRCReconfiguration message or system information. The second initial UL BWP is indicated by another name. The first initial DL BWP is indicated by an initialDownlinkBWP field in an RRC Reconfiguration message or system information, and the second initial DL BWP is indicated by an initialDownlinkBWPRedcap field in an RRC Reconfiguration message or system information.

[0226] The UE is in RRC_CONNECTED state.

[0227] The UE receives an RRCReconfiguration message from the gNB.

[0228] The RRC reconfiguration message includes the configuration of the SCell.

[0229] -SCell settings include firstActiveUplinkBWP-Id and firstActiveDownlinkBWP-Id.

[0230] -firstActiveUplinkBWP-Id is set to 0.

[0231] -firstActiveDownlinkBWP-Id is set to 0.

[0232] -sCellState is set to be deactivated in the SCell settings.

[0233] The UE receives an SCell activation / deactivation MAC CE to activate the SCell from the gNB.

[0234] Activate the SCell When receiving the SCell activation / deactivation MAC CE:

[0235] - The UE activates the SCell.

[0236] - if the UE is a redcap UE and initialUplinkBWPRedcap (i.e. the second initial UL BWP) is configured for this SCell:

[0237] ■ firstActiveUplinkBWP-Id set to 0 indicates initialUplinkBWPRedcap (i.e., the second initial UL BWP); and

[0238] ■ The UE uses the BWP indicated by initialUplinkBWPRedcap (i.e., the second initial UL BWP) when activating the SCell (i.e., activates the BWP);

[0239] Otherwise (i.e., the UE is not a redcap UE or the UE is a redcap UE but initialUplinkBWPRedcap (i.e., the second initial UL BWP) is not configured):

[0240] ■ firstActiveUplinkBWP-Id set to 0 indicates the initialUplinkBWP (i.e., the first initial UL BWP);

[0241] ■The UE uses the BWP (ie, activates the BWP) indicated by the initialUplinkBWP (ie, the first initial UL BWP) when activating the SCell.

[0242] - If the UE is a redcap UE and initialDownlinkBWPRedcap (i.e. the second initial DL BWP) is configured for this SCell:

[0243] ■ firstActiveDownlinkBWP-Id set to 0 indicates initialDownlinkBWPRedcap (i.e., the second initial DL BWP);

[0244] ■The UE uses the BWP (i.e., activates the BWP) indicated by initialDownlinkBWPRedcap (i.e., second initial DL BWP) when activating the SCell.

[0245] Otherwise (i.e. the UE is not a redcap UE or the UE is a redcap UE but initialDownlinkBWPRedcap (i.e. the second initial DL BWP) is not configured):

[0246] ■ the firstActiveDownlinkBWP-Id is set to 0 to indicate the initialDownlinkBWP (i.e., the first initial DL BWP);

[0247] ■The UE uses the BWP (i.e., activates the BWP) indicated by the initialDownlinkBWP (i.e., the first initial DL BWP) when activating the SCell.

[0248] In one embodiment of the present invention, a UE is configured with a first and / or second initial UL BWP on a NUL carrier. A UE is configured with a first and / or second initial UL BWP on a SUL carrier. A UE is configured with a first and / or second initial DL BWP. The first initial UL BWP and the first initial DL BWP of a carrier are for non-RedCap UEs. The second initial UL and the second initial DL BWP of a carrier are for RedCap UEs. A RedCap UE is a UE that supports a reduced number of UE RX / TX antennas, a reduced bandwidth, relaxed UE processing time, relaxed UE processing capability, a reduced maximum number of DL MIMO layers, a relaxed maximum modulation order, relaxed duplex operation, etc. The first initial UL BWP is indicated by an initialUplinkBWP field in an RRCReconfiguration message or system information. The second initial UL BWP is indicated by an initialUplinkBWPRedcap field in an RRCReconfiguration message or system information. The second initial UL BWP is indicated by another name. The first initial DL BWP is indicated by the initialDownlinkBWP field in the RRC Reconfiguration message or the system information, and the second initial DL BWP is indicated by the initialDownlinkBWPRedcap field in the RRC Reconfiguration message or the system information.

[0249] The UE enters RRC_CONNECTED state.

[0250] When the UE enters the RRC_CONNECTED state, it receives a first RRCReconfiguration message from the gNB.

[0251] The first RRCReconfiguration message includes the configuration of the SpCell.

[0252] -SpCell settings include firstActiveUplinkBWP-Id and firstActiveDownlinkBWP-Id.

[0253] -firstActiveUplinkBWP-Id is set to a BWP ID that is not 0.

[0254] -firstActiveDownlinkBWP-Id is set to a non-zero BWP ID.

[0255] The UE activates a DL BWP having a BWP ID indicated by firstActiveDownlinkBWP-Id, and the UE activates a UL BWP having a BWP ID indicated by firstActiveUplinkBWP-Id.

[0256] The UE receives a second RRCReconfiguration message including the configuration of the SpCell.

[0257] -SpCell settings include firstActiveUplinkBWP-Id and firstActiveDownlinkBWP-Id.

[0258] -firstActiveUplinkBWP-Id is set to 0.

[0259] -firstActiveDownlinkBWP-Id is set to 0.

[0260] Upon receipt of the second RRCReconfiguration message:

[0261] -If the UE is a redcap UE and configured for an SpCell that is initialUplinkBWPRedcap (i.e., 2nd initial UL BWP):

[0262] ■ firstActiveUplinkBWP-Id set to 0 indicates initialUplinkBWPRedcap (i.e., the second initial UL BWP); and

[0263] ■ The UE switches the active UL BWP to the BWP indicated by initialUplinkBWPRedcap (ie, the second initial UL BWP).

[0264] - otherwise (i.e., the UE is not a redcap UE or the UE is a redcap UE but initialUplinkBWPRedcap (i.e., the second initial UL BWP) is not configured).

[0265] ■ firstActiveUplinkBWP-Id set to 0 indicates the initialUplinkBWP (i.e., the first initial UL BWP);

[0266] ■ The UE switches the active UL BWP to the BWP indicated by the initialUplinkBWP (ie, the first initial UL BWP).

[0267] - If the UE is a redcap UE and initialDownlinkBWPRedcap (i.e. the second initial DL BWP) has been configured for this SpCell:

[0268] ■ firstActiveDownlinkBWP-Id set to 0 indicates initialDownlinkBWPRedcap (i.e., the second initial DL BWP);

[0269] ■ The UE switches the active UL BWP to the BWP indicated by the initialDownlinkBWPRedcap (i.e., the second initial DL BWP).

[0270] Otherwise (i.e. the UE is not a redcap UE or the UE is a redcap UE but initialDownlinkBWPRedcap (i.e. the second initial DL BWP) is not configured):

[0271] ■ the firstActiveDownlinkBWP-Id is set to 0 to indicate the initialDownlinkBWP (i.e., the first initial DL BWP);

[0272] ■ The UE switches the active UL BWP to the BWP indicated by the initialDownlinkBWP (i.e., the first initial DL BWP).

[0273] FIG. 6 illustrates a block diagram of a terminal according to various embodiments.

[0274] 6, the terminal includes a transceiver 610, a controller 620, and a memory 630. The controller 620 may refer to a circuit, an application-specific integrated circuit (ASIC), or at least one processor. The transceiver 610, controller 620, and memory 630 are configured to perform the operations of the UE shown in the drawings, for example, in FIGS. 1 to 5, or as described above. Although the transceiver 610, controller 620, and memory 630 are illustrated as separate entities, they may be embodied as a single entity, such as a single chip. Alternatively, the transceiver 610, controller 620, and memory 630 may be electrically connected or coupled to each other.

[0275] The transceiver 610 transmits and receives signals to and from other network entities, such as base stations.

[0276] The controller 620 controls the UE to function according to one of the above-mentioned embodiments.

[0277] For example, the control unit 620 identifies that a random access procedure has been initiated in the serving cell, selects a UL carrier for the serving cell, and if a PRACH occasion is not set for an active UL BWP of the selected UL carrier, identifies whether an initial UL BWP for the RedCap UE is set, and if the initial UL BWP for the RedCap UE is set, switches the active UL BWP to the initial UL BWP for the RedCap UE.

[0278] In one embodiment, the operation of the terminal is implemented using a memory 630 that stores the corresponding program code. Specifically, the terminal includes a memory 630 for storing program code for implementing a desired operation. The controller 620 reads and executes the program code stored in the memory 630 using a processor or central processing unit (CPU) to perform the desired operation.

[0279] FIG. 7 illustrates a block diagram of a base station according to various embodiments of the present invention.

[0280] 7, the base station includes a transceiver unit 710, a controller 720, and a memory 730. The transceiver unit 710, the controller 720, and the memory 730 are configured to perform the operations of the network (e.g., gNB) illustrated in the drawings, for example, in FIGS. 1 to 5, or described above. Although the transceiver unit 710, the controller 720, and the memory 730 are illustrated as separate entities, they may be embodied as a single entity, such as a single chip. The transceiver unit 710, the controller 720, and the memory 730 are electrically connected or coupled to each other.

[0281] The transceiver 710 transmits and receives signals to and from other network entities, such as terminals.

[0282] The controller 720 controls the base station to perform functions according to any one of the above-mentioned embodiments. The controller 720 may refer to a circuit, an ASIC, or at least one processor.

[0283] In one embodiment, the operations of the base station are implemented using memory 730 that stores program code. Specifically, the base station includes memory 730 for storing program code that implements a desired operation. The controller 720 reads and executes the program code stored in memory 730 using a processor or CPU to perform the desired operation.

[0284] Although the present invention has been illustrated and described with reference to various embodiments, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention.

[0285] As described above, the embodiments described in the present specification and drawings are merely specific examples presented to easily explain and facilitate understanding of the contents of the present invention, and are not intended to limit the technical scope of the present invention. Therefore, the technical scope of the present invention includes all changes or modifications derived based on the technical idea of ​​the present invention in addition to the embodiments disclosed in the present specification.

[0286] Although the present invention has been described in various embodiments, various changes and modifications may be suggested to those skilled in the art, and the present invention is intended to include such changes and modifications within the scope of the present invention. [Explanation of symbols]

[0287] 610, 710 Transmitter / Receiver 620, 720 Control unit 630, 730 Memory

Claims

1. A method performed by a RedCap (reduced capability) user equipment (UE) of a wireless communication system, comprising: receiving configuration information for a first initial uplink (UL) bandwidth part (BWP) from a base station; identifying that a random access procedure has been initiated in a serving cell; If a physical random access channel (PRACH) occasion is not configured for an active UL BWP, determining whether a second initial UL BWP associated with the RedCapUE is configured; If the second initial UL BWP associated with the RedCap UE is configured, switching the active UL BWP to the second initial UL BWP associated with the RedCap UE; and if the second initial UL BWP associated with the RedCap UE is not configured, switching the active UL BWP to the first initial UL BWP.

2. A step of receiving configuration information for a first initial downlink (DL) BWP from the base station; If the PRACH occasion is not configured for the active UL BWP, identifying whether the serving cell is a special cell (SpCell); If the serving cell is the SpCell, identifying whether a second initial DLBWP associated with the RedCap UE is configured; 2. The method of claim 1, further comprising: if the second initial DL BWP associated with the RedCap UE is configured, switching an active DL BWP to the second initial DL BWP associated with the RedCap UE.

3. 3. The method of claim 2, further comprising: switching the active DL BWP to the first initial DL BWP if the second initial DL BWP associated with the RedCap UE is not configured.

4. The method of claim 1, further comprising: identifying whether a BWP inactivity timer associated with the active DL BWP has expired; If the BWP inactivity timer expires, determining whether a default DL BWP is set; If the default DL BWP is not configured, identifying whether the second initial DL BWP associated with the RedCap UE is configured; 3. The method of claim 2, further comprising: if the second initial DL BWP associated with the RedCap UE is configured, switching the active DL BWP to the second initial DL BWP associated with the RedCap UE.

5. 5. The method of claim 4, further comprising: switching the active DL BWP to the first initial DL BWP if the second initial DL BWP associated with the RedCap UE is not configured.

6. A terminal (user equipment, UE) of a wireless communication system, a transmitter / receiver; a control unit operatively connected to the transceiver unit; The control unit receiving configuration information for a first initial uplink (UL) bandwidth part (BWP) from a base station via the transceiver unit; Identifying that a random access procedure has been initiated in the serving cell; If a PRACH (physical random access channel) occasion is not configured for an active ULBWP, determine whether a second initial UL BWP associated with a reduced capability (RedCap) UE is configured; If the second initial UL BWP associated with the RedCap UE is configured, switching the active UL BWP to the second initial UL BWP associated with the RedCap UE; and 11. The UE, wherein the UE is configured to switch the active UL BWP to the first initial UL BWP when the second initial UL BWP associated with the RedCap UE is not configured.

7. The control unit receiving configuration information for a first initial downlink (DL) BWP from the base station via the transceiver unit; If the PRACH occasion is not configured for the active UL BWP, identify whether the serving cell is a special cell (SpCell); If the serving cell is the SpCell, determine whether a second initial DLBWP associated with the RedCap UE is configured; and 7. The UE of claim 6, wherein, when the second initial DL BWP associated with the RedCap UE is configured, the UE is configured to switch an active DL BWP to the second initial DL BWP associated with the RedCap UE.

8. The control unit 8. The UE of claim 7, wherein the UE is configured to switch the active DL BWP to the first initial DL BWP when the second initial DL BWP associated with the RedCap UE is not configured.

9. The control unit Identifying whether a BWP inactivity timer associated with the active DL BWP has expired; If the BWP inactivity timer expires, determine whether a default DL BWP is set; If the default DL BWP is not configured, determining whether the second initial DL BWP associated with the RedCap UE is configured; and 8. The UE of claim 7, wherein the UE is configured to switch the active DL BWP to the second initial DL BWP associated with the RedCap UE when the second initial DL BWP associated with the RedCap UE is configured.

10. The control unit 10. The UE of claim 9, wherein the UE is configured to switch the active DL BWP to the first initial DL BWP when the second initial DL BWP associated with the RedCap UE is not configured.

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