Method and apparatus for performing random access in a wireless communication system

Abstract

A method for performing random access by a terminal in a wireless communication system is provided. The method includes: identifying a random access opportunity of an active uplink (UL) bandwidth part (BWP) configured for a serving cell; when the serving cell is a specific cell (SpCell) and an identification (ID) of an active downlink (DL) BWP does not correspond to an ID of an active UL BWP, switching the active DL BWP to a DL BWP having an ID corresponding to the ID of the active UL BWP based on BWP configuration information of the serving cell; and performing random access on the switched DL BWP.

Description

[0001] This application is a divisional application of the invention patent application with the application date of March 28, 2019, application number 201980023015.0, and invention name “Method and device for performing random access in a wireless communication system”. Technical Field

[0002] The present disclosure relates to a wireless communication system, and more particularly to a method for performing random access in a wireless communication system. Background Art

[0003] In order to meet the increased demand for wireless data services since the commercialization of the fourth generation (4G) communication system, efforts have been made to develop improved fifth generation (5G) or pre-5G communication systems. Therefore, 5G or pre-5G communication systems are also referred to as "beyond 4G network systems", "late long term evolution (LTE) systems" or "next generation mobile communication systems". In order to achieve high data rates, 5G communication systems have been developed to be implemented in ultra-high frequency bands (millimeter wave (mmWave)) (e.g., 60 GHz band). In order to reduce the path loss of such ultra-high frequency bands and increase the propagation distance of radio waves in 5G communication systems, various technologies such as beamforming, massive multiple input multiple output (massive MIMO), full-size MIMO (FD-MIMO), array antennas, analog beamforming and massive antennas are being developed. In order to improve the system network of the 5G communication system, various technologies (such as evolved small cells, advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device communication (D2D), wireless backhaul, mobile networks, cooperative communication, coordinated multi-point (CoMP) and interference cancellation) have been developed. In addition, for the 5G communication system, advanced coding and modulation (ACM) technologies (such as hybrid frequency shift keying (FSK) and orthogonal amplitude modulation (QAM) (FQAM) and sliding window superposition coding (SWSC)) and advanced access technologies (such as filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA)) have been developed.

[0004] In other areas, the Internet has evolved from a human-based connected network where humans create and consume information to the Internet of Things (IoT), in which distributed elements such as objects exchange information with each other for processing. Recently, the Internet of Everything (IoE) has emerged, combining IoT technology with technologies for processing big data through connections to cloud servers. Implementing the IoT requires various technological elements, such as sensing technology, wired / wireless communication and network architecture, service interface technology, and security technology. In recent years, research has focused on technologies related to sensor networks for connecting objects, machine-to-machine (M2M) communication, and machine-type communication (MTC). Within the IoT, intelligent Internet technology (IT) services can be provided to collect and analyze data obtained from connected objects, thereby creating new value in human life. With the integration and combination of existing information technology (IT) and various industries, the IoT can be applied to a variety of fields, such as smart homes, smart buildings, smart cities, smart cars or connected vehicles, smart grids, healthcare, smart appliances, and advanced medical services.

[0005] Attempts are underway to apply 5G communication systems to IoT networks. For example, technologies related to sensor networks, machine-to-machine (M2M) communications, and machine-to-communication (MTC) are enabled by 5G communication technologies, including beamforming, multiple-input multiple-output (MIMO), and array antennas. Cloud RAN, as an application of these big data processing technologies, exemplifies the convergence of 5G and IoT technologies.

[0006] As described above, with the development of wireless communication systems, various services can now be provided, and therefore, a method of smoothly providing these services is required.

[0007] The above information is presented as background information only to assist in understanding the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above content may be applicable as prior art with respect to the present disclosure. Summary of the Invention

[0008] Technical issues

[0009] As described above, with the development of wireless communication systems, various services can now be provided, and therefore, a method for smoothly providing these services is required.

[0010] Technical Solution

[0011] A method for performing random access by a terminal in a wireless communication system is provided. The method includes: identifying a random access opportunity of an active uplink (UL) bandwidth part (BWP) configured for a serving cell; when the serving cell is a specific cell (SpCell) and an identification (ID) of an active downlink (DL) BWP does not correspond to an ID of an active UL BWP, switching the active DL BWP to a DL BWP having an ID corresponding to the ID of the active UL BWP based on BWP configuration information of the serving cell; and performing random access on the switched DL BWP.

[0012] Beneficial effects

[0013] Provided is a method for performing random access in a primary cell (PCell) or a secondary cell (SCell) using a frequency merging technique utilizing a portion of bandwidth. Also provided is a method for differentially applying a method for successfully performing random access according to the type of random access performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent through the following description taken in conjunction with the accompanying drawings, in which:

[0015] Figure 1A is a structural diagram of a Long Term Evolution (LTE) system referred to for describing the embodiments of the present disclosure;

[0016] Figure 1B is a diagram of a radio protocol architecture in an LTE and New Radio (NR) system to which reference is made for describing embodiments of the present disclosure;

[0017] Figure 1C is a diagram for describing a carrier aggregation (CA) technology according to an embodiment of the present disclosure;

[0018] Figure 1D is a diagram for describing a process of a user equipment (UE) performing contention-based random access on a Node B (NB) according to an embodiment of the present disclosure;

[0019] Figure 1E is a diagram for describing a process in which a UE performs non-contention-based random access on a NB according to an embodiment of the present disclosure;

[0020] Figure 1FA 、 Figure 1FB and Figure 1FC is a diagram for describing a scenario in which a portion of a frequency band is applied in a wireless communication system according to an embodiment of the present disclosure;

[0021] Figure 1Gis a diagram for describing the operation of a UE according to an embodiment of the present disclosure;

[0022] Figure 2A is a diagram for describing a process in which a UE performs contention-based random access and non-contention-based random access on a NB according to an embodiment of the present disclosure;

[0023] Figure 2B is a diagram for describing the operation of a UE according to the first embodiment of the present disclosure;

[0024] Figure 2C is a diagram for describing the operation of a UE according to the second embodiment of the present disclosure; and

[0025] Figure 2D is a block diagram of a UE according to an embodiment of the present disclosure.

[0026] Throughout the drawings, like reference numerals will be understood to refer to like parts, components, and structures. DETAILED DESCRIPTION

[0027] Best Mode

[0028] Aspects of the present disclosure will at least address the above-mentioned problems and / or disadvantages and provide at least the following advantages. Therefore, one aspect of the present disclosure is to provide a method for performing random access in a primary cell (PCell) or a secondary cell (SCell) when using a frequency combining technique that utilizes a portion of a bandwidth.

[0029] Another aspect of the present disclosure is to provide a method of differentially applying a method for successfully performing random access according to a type of random access being performed.

[0030] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments.

[0031] According to one aspect of the present disclosure, a method for performing random access by a terminal in a wireless communication system is provided. The method includes: identifying a random access opportunity of an active uplink (UL) bandwidth part (BWP) configured for a serving cell; when the serving cell is a specific cell (SpCell) and an identification (ID) of an active downlink (DL) BWP does not correspond to an ID of an active UL BWP, switching the active DL BWP to a DL BWP having an ID corresponding to the ID of the active UL BWP based on BWP configuration information of the serving cell; and performing random access on the switched DL BWP.

[0032] The BWP configuration information may include the ID of the active DL BWP and the ID of the active UL BWP.

[0033] When the serving cell is an SCell, random access may be initiated based on a physical downlink control channel (PDCCH) with a random access preamble index.

[0034] Random access may include contention-based random access.

[0035] According to another aspect of the present disclosure, a method for a base station to perform random access in a wireless communication system is provided. The method includes: transmitting a radio resource control (RRC) message including BWP configuration information regarding an active downlink (DL) bandwidth part (BWP) and an active uplink (UL) BWP of a serving cell; and performing random access based on the BWP configuration information, wherein, when the serving cell is a SpCell and an identification (ID) of the active downlink (DL) BWP does not correspond to an ID of an active UL BWP, the active DL BWP is switched to a DL BWP having an ID corresponding to the ID of the active UL BWP.

[0036] The method may further include transmitting a physical downlink control channel (PDCCH) with a random access preamble index, wherein when the serving cell is an SCell, random access may be initiated based on the PDCCH.

[0037] According to another aspect of the present disclosure, a terminal for performing random access in a wireless communication system is provided. The terminal includes: a transceiver; and at least one processor coupled to the transceiver and configured to: identify a random access opportunity of an active UL BWP configured for a serving cell; when the serving cell is a SpCell and an identification (ID) of an active downlink (DL) BWP does not correspond to the ID of the active UL BWP, switching the active DL BWP to a DL BWP having an ID corresponding to the ID of the active UL BWP based on BWP configuration information of the serving cell; and perform random access on the switched DL BWP.

[0038] According to another aspect of the present disclosure, a base station for performing random access in a wireless communication system is provided, the base station including: a transceiver; and at least one processor coupled to the transceiver and configured to: send a radio resource control (RRC) message including BWP configuration information about an active downlink (DL) BWP and an active uplink (UL) BWP of a serving cell; and perform random access based on the BWP configuration information, wherein, when the serving cell is a SpCell and an identification (ID) of the active downlink (DL) BWP does not correspond to the ID of the active UL BWP, the active DL BWP is switched to a DL BWP having an ID corresponding to the ID of the active ULBWP.

[0039] The processor may also be configured to send a physical downlink control channel (PDCCH) with a random access preamble index, and when the serving cell is an SCell, may initiate random access based on the PDCCH.

[0040] According to another embodiment of the present disclosure, a computer-readable recording medium has recorded thereon a process for executing a method.

[0041] Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the accompanying drawings, discloses various embodiments of the disclosure.

[0042] Mode for the Invention

[0043] The following description, with reference to the accompanying drawings, is provided to facilitate a more comprehensive understanding of the various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to aid understanding, but these specific details are to be considered as exemplary only. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. Furthermore, descriptions of well-known functions and configurations may be omitted for clarity and brevity.

[0044] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Therefore, it will be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purposes only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

[0045] It should be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

[0046] In the following description, terms for identifying access nodes, terms referring to network entities, terms referring to messages, terms indicating interfaces between network entities, terms indicating various identification information, etc. are provided only for the purpose of convenience of description. Therefore, the present disclosure is not limited to the following terms, and other terms referring to objects with equivalent technical meanings may be used.

[0047] For ease of description, the present disclosure uses terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standard, or uses modified terms and names based on the terms and names. However, the present disclosure is not limited to the terms and names and can be equally applied to systems that comply with other standards. In particular, one or more embodiments of the present disclosure can be applied to 3GPP New Radio (NR), a fifth-generation mobile communication standard.

[0048] Throughout the disclosure, the expression "at least one of a, b, or c" simply means a, b, c, a and b, a and c, b and c, a, b, and c, all or variations thereof.

[0049] Figure 1A This is a diagram of the structure of an LTE system referenced for describing the embodiments of the present disclosure. The NR system actually has the same structure as the LTE system.

[0050] Reference Figure 1A , a wireless communication system may include multiple Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node Bs (eNBs) 1a-05, 1a-10, 1a-15, and 1a-20, a Mobility Management Entity (MME) 1a-25, and a Serving Gateway (S-GW) 1a-30. A User Equipment (UE) 1a-35 may connect to an external network via the eNBs 1a-05 to 1a-20 and the S-GW 1a-30.

[0051] eNB 1a-05 to 1a-20 can provide wireless connection to UEs accessing the network as access nodes of the cellular network. That is, eNB 1a-05 to 1a-20 can support the connection between the UE and the core network (CN) via scheduling by collecting status information of the UE's service user services (such as buffer status, available transmission power status, and channel status). MME 1a-25 is a device that undertakes various control functions in addition to the UE's mobility management function and is connected to multiple base stations, and S-GW 1a-30 is a device used as a data bearer. In addition, MME 1a-25 and S-GW 1a-30 can perform authentication, bearer management, etc. on UEs connected to the network, and process packets received from eNB 1a-05 to 1a-20 or packets to be sent to eNB1a-05 to 1a-20.

[0052] Figure 1B This is a diagram of radio protocol architecture in LTE and NR systems, which is referenced for the purpose of describing embodiments of the present disclosure.

[0053] Reference Figure 1BThe radio protocols of the LTE system may include Packet Data Convergence Protocol (PDCP) 1b-05 and 1b-40, Radio Link Control (RLC) 1b-10 and 1b-35, Medium Access Control (MAC) 1b-15 and 1b-30, and Physical Entity (PHY) 1b-20 and 1b-25 in the corresponding UE and eNB / gNB. PDCP 1b-05 and 1b-40 may perform operations including Internet Protocol (IP) header compression / decompression, and RLC 1b-10 and 1b-35 may reconfigure PDCP packet data units (PDUs) to have an appropriate size. MAC 1b-15 and 1b-30 connect to multiple RLC entities configured in one UE and may multiplex RLC PDUs into MAC PDUs and demultiplex RLC PDUs from MAC PDUs. PHY 1b-20 and 1b-25 can perform operations of channel coding and modulating upper layer entity data and converting the upper layer entity data into orthogonal frequency division multiplexing (OFDM) symbols over a wireless channel, or demodulating and channel decoding OFDM symbols received over a wireless channel and transmitting the decoded data to an upper layer entity. To perform additional error correction, PHY 1b-20 and 1b-25 use hybrid automatic repeat request (HARQ), and the receiver can transmit one bit indicating an acknowledgement (ACK) or negative acknowledgement (NACK) regarding a packet sent from the transmitter. This is referred to as HARQ ACK / NACK information. Downlink (DL) HARQ ACK / NACK information regarding uplink (UL) data transmission can be transmitted via the physical HARQ indicator channel (PHICH) physical channel in LTE. In NR, whether a packet is to be retransmitted or newly transmitted can be determined via scheduling information from the UE on the physical dedicated control channel (PDCCH), which is a channel for transmitting DL / UL resource allocation, etc. This is because asynchronous HARQ is applied in NR. UL HARQ ACK / NACK information about DL data transmission can be transmitted via the physical uplink control channel (PUCCH) physical channel or the physical uplink shared channel (PUSCH) physical channel. PUCCH is usually transmitted in the UL of the primary cell (PCell) described later, but when supported by the UE, PUCCH can be transmitted in the UL of the secondary cell (SCell) described later, and such SCell can be called a PUCCH SCell.

[0054] Although not in Figure 1B , but respective radio resource control (RRC) entities exist as upper layer entities of the PDCP entities 1b-05 and 1b-40 of the UE and the eNB, and the RRC entities can exchange setup control messages related to access and measurement for controlling radio resources.

[0055] PHY 1b-20 or 1b-25 may include one or more frequencies / carriers, and the technology for simultaneously setting and using multiple frequencies is called carrier aggregation (CA). According to CA technology, instead of using only one carrier for communication between the UE and the base station (i.e., eNB), a primary carrier and multiple secondary carriers are used, so the number of secondary carriers can greatly increase the transmission capacity. In LTE, a cell served by a base station using a primary carrier is called a PCell, and a cell served by a base station using a secondary carrier is called an SCell.

[0056] Figure 1C is a diagram for describing the CA technology according to an embodiment of the present disclosure.

[0057] Reference Figure 1C In a base station, multiple carriers can typically be transmitted and received across several frequency bands. For example, according to prior art, when base station 1c-05 transmits carrier 1c-15 with a primary frequency of f1 and carrier 1c-10 with a primary frequency of f3, a UE transmits and receives data using only one of the two carriers. However, a UE with CA functionality can simultaneously transmit and receive data using multiple carriers. Base station 1c-05 can allocate more carriers to UE 1c-30 with CA functionality, depending on the situation, thereby increasing the transmission rate of UE 1c-30.

[0058] When assuming that a cell generally includes one forward carrier and one backward carrier transmitted and received by one base station, CA can be understood as a way for a UE to simultaneously transmit and receive data through multiple cells. In this way, the maximum transmission rate can be increased in proportion to the number of aggregated carriers.

[0059] Hereinafter, in the embodiments of the present disclosure, the expression "a UE receives data via a random forward carrier or transmits data via a random backward carrier" has the same meaning as "data transmitted and received using a control channel and a data channel provided by a cell corresponding to the primary frequency and frequency bandwidth of a designated corresponding carrier." Furthermore, for ease of description, one or more embodiments of the present disclosure will be described below with reference to an LTE system. However, one or more embodiments of the present disclosure can be applied to various wireless communication systems supporting carrier aggregation.

[0060] Figure 1D is a diagram for describing a process in which a UE performs contention-based random access on a NB according to an embodiment of the present disclosure.

[0061] Contention-based random access may be performed in various situations where initial access, re-access, handover, or other random access is required.

[0062] Reference Figure 1D , in operation 1d-11, UE 1d-01 may send a random access preamble through a physical channel for random access for accessing NB 1d-03. Here, the physical channel for random access is referred to as a physical random access channel (PRACH), and one or more UE 1d-01 may simultaneously send a random access preamble via corresponding PRACH resources. PRACH resources may span one subframe, or may use only some symbols in one subframe. Information about PRACH resources may be included in the system information broadcast by NB 1d-03, so that UE 1d-01 determines which time-frequency resource to send the random access preamble via. The random access preamble is a specific sequence specifically designed to be received even before being fully synchronized with NB 1d-03, and there may be multiple preamble indices depending on the standard. When there are multiple preamble indices, the random access preamble sent by UE 1d-01 may be randomly selected by UE 1d-01, or may be a specific preamble specified by NB 1d-03.

[0063] When the random access preamble is received, in operation 1d-21, NB 1d-03 sends a random access response (RAR) message to UE 1d-01. The RAR message may be sent in RAR window 1d-23. The RAR message may include at least one of index information of the random access preamble used in operation 1d-11, UL transmission timing correction information, UL resource allocation information to be used in subsequent operations (i.e., 1d-31), or temporary UE identification information. For example, the index information of the random access preamble may be sent to identify which preamble the RAR message responds to when multiple UEs send different preambles to attempt random access in operation 1d-11. The UL resource allocation information is detailed information about the resources to be used by UE 1d-01 in operation 1d-31, and may include the physical location and size of the resources, the modulation and coding scheme used for transmission, transmission power adjustment information, etc. The temporary UE identity information is a value that is transmitted when UE 1d-01 having transmitted a random access preamble initially accesses NB 1d-03 because UE 1d-01 does not have an identity allocated by NB 1d-03 for communicating with NB 1d-03.

[0064] The RAR message needs to be sent within a specific time period after a specific time from the time the random access preamble is sent. This specific time period is called the RAR window. The RAR window begins after the specific time after the first random access preamble is sent. The specific time period may be equal to or less than a subframe unit (1ms). In addition, the length of the RAR window may be a specific value set by NB 1d-03 for each PRACH resource in the system information message broadcast by NB 1d-03 or for one or more PRACH resource sets.

[0065] When transmitting the RAR message, NB 1d-03 schedules the RAR message through the PDCCH and may scramble the corresponding scheduling information using a random access radio network temporary identifier (RA-RNTI). When the RA-RNTI is mapped to the PRACH resource for transmitting the random access preamble in operation 1d-11, the UE 1d-01 that has transmitted the random access preamble by using a specific PRACH resource determines whether the RAR message is received by attempting PDCCH reception based on the corresponding RA-RNTI. That is, when the RAR message is received as Figure 1D When responding to the random access preamble sent by UE 1d-01 in operation 1d-11, the RA-RNTI used in the RAR message scheduling information may include information about the transmission of operation 1d-11. In this regard, the RA-RNTI can be calculated by the following equation (1):

[0066] RA-RNTI=1+s_id+14x t_id+14x 80x f_id+14x 80x 8x ul_carrier_id...(Equation 1)

[0067] Here, s_id represents the index corresponding to the first OFDM symbol from which transmission of the random access preamble sent in operation 1d-11 starts, and may have a value of 0≤s_id<14 (i.e., the maximum number of OFDM symbols in one slot). In addition, t_id represents the index corresponding to the first slot from which transmission of the random access preamble sent in operation 1d-11 starts, and may have a value of 0≤t_id<80 (i.e., the maximum number of slots in one system frame (10ms)). In addition, f_id represents information about PRACH resources on the frequency in which the random access preamble sent in operation 1d-11 is sent, and may have a value of 0≤f_id<8 (i.e., the maximum number of PRACHs on the frequency at the same time). In addition, ul_carrier_id is a factor used to distinguish whether the normal UL (NUL) transmits the random access preamble (0 in this case) or the supplementary UL (SUL) transmits the random access preamble (1 in this case) when two carriers are used in the UL of one cell.

[0068] In operation 1d-31, the UE 1d-01 having received the RAR message sends a message according to the above-mentioned various purposes by using the resources allocated to the RAR message. Such a message is Figure 1D The third message sent in the random access preamble of operation 1d-11 or 1d-13 may be referred to as Msg1, and the RAR message of operation 1d-21 may be referred to as Msg2. For example, Msg3 sent by UE 1d-01 may include an RRCConnectionRequest message as an RRC entity message for initial access, an RRCConnectionReestablishmentRequest message for reaccess, or an RRCConnectionReconfigurationComplete message for handover. Optionally, a buffer status report (BSR) message for requesting resources may be sent.

[0069] When Msg3 is initially transmitted (for example, when Msg3 does not include the NB identification information previously allocated to UE 1d-01), UE 1d-01 may receive a contention resolution message from NB 1d-03 in operation 1d-41. The contention resolution message includes all the information included in Msg3 transmitted by UE 1d-01, so even when multiple UEs select the same random access preamble in operation 1d-11 or 1d-13, UE 1d-01 to receive the contention resolution message can be identified.

[0070] Figure 1E is a diagram for describing a process in which a UE performs non-contention-based random access on a NB according to an embodiment of the present disclosure.

[0071] Reference Figure 1E , when UL timing adjustment is required or during handover, when NB 1e-03 allocates specific random access resources (specific preamble index and / or PRACH resources at specific time / frequency) to UE 1e-01, UE 1e-01 can perform non-contention based random access.

[0072] In operation 1e-11, NB 1e-03 may allocate exclusive random access resources to UE 1e-01, allowing UE 1e-01 to perform non-contention-based random access. Here, the exclusive random access resources may be specific preamble indexes and / or PRACH resources at specific time / frequency. Furthermore, information regarding the exclusive random access may be allocated via a PDCCH or transmitted via a message from an RRC entity. The message from the RRC entity may include an RRCReconfiguration message.

[0073] Therefore, at operation 1e-21, UE 1e-01 may transmit a random access preamble via the allocated exclusive random access resources.

[0074] Upon receiving the random access preamble, in operation 1e-31, NB 1e-03 may send a RAR message to UE 1e-01. The RAR message may include at least one of index information of the random access preamble used in operation 1e-21, UL transmission timing correction information, UL resource allocation information to be used in subsequent operations, or temporary UE identification information. For example, the index information of the random access preamble may be sent to identify which preamble the RAR message responds to when a plurality of UEs transmit different preambles to attempt random access in operation 1e-11. The UL resource allocation information is detailed information about resources to be used by UE 1e-01 after receiving the RAR message, although not in operation 1e-21. Figure 1E , but UL can be sent via the corresponding resources after receiving the RAR message. The temporary UE identification information is a value that is sent when UE 1e-01, which has sent a random access preamble, initially accesses NB 1e-03 because UE 1e-01 does not have an identity allocated by NB 1e-03 for communicating with NB 1e-03.

[0075] The RAR message needs to be sent within a specific time period after a specific time from the time the random access preamble is sent, and the specific time period is referred to as the RAR window 1e-23. The RAR window may begin after a specific time after the first random access preamble is sent. The specific time may be equal to or less than a subframe unit (1ms). In addition, the length of the RAR window may be a specific value set by NB 1e-03 for each PRACH resource in the system information message broadcast by NB 1e-03 or for one or more PRACH resource sets.

[0076] When transmitting the RAR message, the NB 1e-03 schedules the RAR message through the PDCCH and can scramble the corresponding scheduling information using the RA-RNTI. When the RA-RNTI is mapped to the PRACH resource for transmitting the random access preamble in operation 1e-11, the UE 1e-01 that has transmitted the random access preamble by using the specific PRACH resource can determine whether the RAR message is received by attempting PDCCH reception based on the corresponding RA-RNTI. That is, when the RAR message is a Figure 1EWhen responding to the random access preamble sent by UE 1e-01 in operation 1e-11, the RA-RNTI used in the RAR message scheduling information may include information about the transmission of operation 1e-11. In this regard, the RA-RNTI can be calculated by the following equation (2):

[0077] RA-RNTI=1+s_id+14x t_id+14x 80x f_id+14x 80x 8x ul_carrier_id...(Equation 2)

[0078] Here, s_id represents the index corresponding to the first OFDM symbol at which transmission of the random access preamble sent in operation 1e-11 starts, and may have a value of 0≤s_id<14 (i.e., the maximum number of OFDM symbols in one slot). In addition, t_id represents the index corresponding to the first slot at which transmission of the random access preamble sent in operation 1e-11 starts, and may have a value of 0≤t_id<80 (i.e., the maximum number of slots in one system frame (10ms)). In addition, f_id represents to which PRACH resource the random access preamble is transmitted on a frequency in operation 1e-11, and may have a value of 0≤f_id<8 (i.e., the maximum number of PRACHs on a frequency at the same time). In addition, ul_carrier_id is a factor used to distinguish whether the random access preamble is transmitted by the NUL (0 in this case) or the SUL (1 in this case) when two carriers are used in the UL of one cell.

[0079] When receiving the RAR message corresponding to the transmission of the random access preamble, the UE 1e-01 that has performed the non-contention-based random access may determine that the non-contention-based random access is successful. The UE 1e-01 may transmit a message to the UL allocated via the RAR message.

[0080] Figure 1FA 、 1FB 1FC is a diagram for describing a scenario in which a partial frequency band is applied in a wireless communication system according to an embodiment of the present disclosure.

[0081] The partial band (Bandwidth Partition (BWP)) application technology instructs the UE to perform communication by using only the BWP within the system bandwidth used by one cell. BWP can be used to reduce UE manufacturing costs or UE energy saving. The base station can set the BWP only for UEs that support it.

[0082] Reference Figures 1FA to 1FC ,There are mainly three types of BWP operation scenarios.

[0083] Reference Figure 1FAThe first scenario involves configuring a BWP for a UE that only supports a small BWP (1f-10), which is less than the system bandwidth (1f-05) used by the cell. To reduce manufacturing costs, a specific UE can be developed to support only a limited bandwidth. The UE needs to report to the base station that it only supports the limited bandwidth, so the base station can configure a BWP equal to or less than the maximum bandwidth supported by the UE.

[0084] Reference Figure 1FB The second scenario is to configure BWP for UE energy saving. For example, although the UE can perform communication by using the entire system bandwidth 1f-15 used by the cell or by using its BWP2 1f-20, the base station can configure a smaller BWP1 1f-25 for energy saving.

[0085] Reference Figure 1FC The third scenario involves configuring individual BWPs corresponding to different parameter sets. Parameter sets are used to diversify the physical entity configuration based on various service requirements to achieve optimal data transmission. For example, in an orthogonal frequency division multiple access (OFDMA) structure comprising multiple subcarriers, the subcarrier spacing can be variably adjusted based on specific requirements. The UE can perform communications by using multiple parameter sets simultaneously. In this case, because the physical entity configurations corresponding to the parameter sets are different, each BWP 1f-30 and 1f-35 can be configured to correspond to a different parameter set.

[0086] There may be multiple BWPs for each of DL and UL within one serving cell. Therefore, when a UE performs the above-mentioned random access and sends a random access preamble via a UL BWP, when there are multiple DL BWPs, it may be ambiguous as to which DL BWP the UE will receive the RAR response through. To eliminate this ambiguity, a link between DL BWP and UL BWP may be defined. For example, when a UE sends a preamble to UL BWP no. 3 of a serving cell (e.g., PCell) within a serving cell, the ambiguity may disappear when receiving the RAR response via DL BWP no. 3 of the serving cell. However, when the UE performs random access via an SCell in the above-mentioned CA case, the preamble may be sent via the SCell and the RAR response may be received via the PCell. In this case, random access is successfully performed only when the DL BWP of the PCell of the UE for receiving the RAR response is defined.

[0087] Figure 1G is a diagram for describing the operation of a UE according to an embodiment of the present disclosure.

[0088] Reference Figure 1G, when the UE is in idle mode, the UE can perform random access according to the information broadcast by the base station to send an RRC connection request message and receive an RRC connection configuration message, thereby performing RRC connection configuration in operation 1g-03.

[0089] The UE may obtain the BWP configuration information (including the DL DWP ID and the UL BWP ID) of the PCell in operation 1g-05 through the RRC connection configuration message or through a subsequent additional RRC message (e.g., an RRCReconfiguration message). Therefore, as described above, the UE may determine the DL / UL BWP linkage or correspondence based on the BWP ID, or may directly receive linkage / mapping information of the DL BWP ID and the UL BWP ID through a signaling message.

[0090] In operation 1g-07, the UE may additionally configure multiple SCells for the CA function from the base station. Here, the UE may obtain BWP configuration information (including DL BWP ID and UL BWP ID) for each serving cell. As described above, the DL / UL BWP linkage may be determined based on the BWP ID, or the linkage / mapping information of the DL BWP ID and the UL BWP ID may be directly received via a signaling message. Here, depending on the type of method described below, the UE may additionally determine or be directly signaled the DL BWP ID of the PCell with respect to the corresponding UL BWP ID. For example, when the UL BWP ID of SCell no.1 is no.3, the DL BWP ID of the corresponding PCell may be mapped to no.3 (indirect mapping). As another example, the base station may directly map the DL BWP ID of the PCell to no.3 or another BWP ID (direct mapping) with respect to the UL BWPID no.3 of SCell no.1. When indirect mapping is used, the number of UL BWP IDs of the SCell may be greater than the number of DL BWP IDs of the PCell. In this case, when random access is performed via a UL BWP ID having a value greater than the maximum DL BWP ID of the PCell, the DL BWP ID of the corresponding PCell may have a specific value. The specific value may be set to 0, may be set to the maximum DL BWP ID of the PCell, or may be directly set by the base station through a message of the RRC entity.

[0091] In operation 1g-09, the UE may perform a reference to the PCell or SCell. Figure 1D or Figure 1E The contention-based random access or non-contention-based random access described.

[0092] Here, the UE may determine whether to switch (change) the DL BWP by using one of the following three methods, but the embodiment is not limited thereto.

[0093] Method 1: When the UE performs contention-based random access, when the DL BWP ID of the serving cell (PCell or SCell) on which the contention-based random access is performed - the UL BWP ID mapped to the serving cell - is different from the current DL BWP ID of the serving cell, the UE performs BWP switching, and when the UE performs non-contention-based random access, even when the DL BWP ID for performing non-contention-based random access, which is mapped to the UL BWP ID of the serving cell, is different from the current DL BWP ID of the serving cell, the UE does not perform BWP switching.

[0094] Method 2: When the UE performs random access on the PCell, if the DL BWP ID of the current PCell is different from the DL BWP ID of the PCell mapped to the UL BWP ID of the PCell on which the random access is performed, the UE may switch the DL BWP ID of the current PCell to the DL BWP ID of the PCell mapped to the UL BWP ID of the PCell on which the random access is performed. However, when the UE performs random access on the SCell, even if the DL BWP ID of the PCell or SCell mapped to the UL BWPID of the SCell on which the random access is performed is different from the current DL BWP ID, the UE does not perform BWP switching.

[0095] Method 3: When the UE performs random access on a PCell or SCell, when the DL BWP ID of the current PCell is different from the DL BWP ID of the PCell mapped to the UL BWP ID of the serving cell on which the random access is performed, the UE may switch the DL BWP ID of the current PCell to the DL BWP ID of the PCell mapped to the UL BWP ID of the serving cell (PCell or SCell) on which the random access is performed.

[0096] When the UE determines in operation 1g-11 that it is necessary to switch the DL BWP during random access according to one of the methods, in operation 1g-13, the UE may perform random access after switching the DL BWP of the serving cell. When it is determined that it is not necessary to switch the DL BWP, in operation 1g-15, the UE may perform random access in the currently active BWP.

[0097] The details regarding the PCell described above can be applied to the primary / secondary cell group (SCG) cell. In the case of dual connectivity where a UE is simultaneously connected to and uses two NBs, in addition to being used as the PCell for the primary NB, the PCell in the secondary NB is also used. Furthermore, the PCell and SpCell are collectively referred to as a specific cell (SpCell), and the details regarding the PCell can also be applied to the SpCell.

[0098] Figure 2A is a diagram for describing a process in which a UE performs contention-based random access and non-contention-based random access on a NB according to an embodiment of the present disclosure.

[0099] Random access may be performed in various situations where initial access, re-access, handover, or other random access is required.

[0100] Reference Figure 2A In the current embodiment of the present disclosure, the process of contention-based random access is mainly described. In the process of non-contention-based random access, there may be a process of allocating exclusive random access resources before the non-contention-based random access, so that NB 2a-03 performs non-contention-based random access on UE 2a-01 in operation 2a-09. The exclusive random access resource can be a specific preamble index and / or PRACH resource at a specific time / frequency. In addition, information about the exclusive random access can be allocated via PDCCH or sent via a message of the RRC entity. The message of the RRC entity may include an RRCReconfiguration message. Therefore, when there is an exclusive random access resource allocated from NB2a-03 for the currently performed non-contention-based random access, UE 2a-01 can send a random access preamble via the exclusive random access resource. In addition, during the non-contention-based random access, when the preamble sent by UE 2a-01 is present in the RAR message described below, it is determined that the non-contention-based random access has been successfully performed, and the process of non-contention-based random access can be ended.

[0101] Hereinafter, a process of contention-based random access will be described.

[0102] In operation 2a-11, UE 2a-01 may send a random access preamble via a physical channel for random access for accessing NB 2a-03. Here, the physical channel for random access is referred to as PRACH, and one or more UEs 2a-01 may simultaneously send random access preambles via corresponding PRACH resources. PRACH resources may span a subframe, or may use only some symbols in a subframe. Information about PRACH resources may be included in the system information broadcast by NB 2a-03, so that UE 2a-01 determines which time-frequency resource to send the random access preamble via. The random access preamble is a specific sequence specifically designed to be received even before full synchronization with NB 2a-03, and depending on the standard, there may be multiple preamble indices. When there are multiple preamble indices, the random access preamble sent by UE 2a-01 may be randomly selected by UE 2a-01, or may be a specific preamble specified by NB 2a-03.

[0103] When receiving the random access preamble (or a preamble sent by another UE), in operation 2a-21, NB 2a-03 sends a RAR message to UE 2a-01. The RAR message may include at least one of index information of the random access preamble used in operation 2a-11, UL transmission timing correction information, UL resource allocation information to be used in subsequent operations (i.e., operation 2a-31), or temporary UE identification information. For example, the index information of the random access preamble may be sent to identify which preamble the RAR message responds to when multiple UEs send different preambles to attempt random access in operation 2a-11. The UL resource allocation information is detailed information about the resources to be used by UE 2a-01 in operation 2a-31, and may include the physical location and size of the resources, the modulation and coding scheme used for transmission, transmission power adjustment information, etc. The temporary UE identification information is a value that is transmitted when UE 2a-01 having transmitted a random access preamble initially accesses NB 2a-03 because UE 2a-01 does not have an identity allocated by NB 2a-03 for communicating with NB 2a-03.

[0104] Furthermore, when too many UEs 2a-01 are performing contention-based random access due to the amount of PRACH received energy, or when the number of random access preambles received via the PRACH within a specific time period is determined to be equal to or greater than a specific number, UE 2a-01 may receive a subheader including backoff indicator information in the RAR message. The subheader is located at the very beginning of the RAR message. The backoff indicator is 4 bits in size, and its value is shown in Table 1 below.

[0105] [Table 1] Backoff indicator

[0106]

[0107]

[0108] When UE 2a-01 receives only information of the backoff indicator and does not receive a response to the contention-based preamble within the time period of the "RAR window" described below, UE 2a-01 may select a random number between 0 and the value received when retransmitting the contention-based preamble and delay the preamble retransmission time by the selected random number during the backoff period of 2a-61.

[0109] The RAR message needs to be sent within a specific time period after a specific time from the time the random access preamble is sent. This specific time period is referred to as the RAR window 2a-51 or 2a-53. The RAR window begins after the specific time after the first random access preamble is sent. The specific time period may be equal to or less than a subframe unit (2ms). In addition, the length of the RAR window may be a specific value set by NB 2a-03 for each PRACH resource in the system information message broadcast by NB 2a-03 or for one or more PRACH resource sets.

[0110] When transmitting the RAR message, NB 2a-03 schedules the RAR message through PDCCH and can scramble the corresponding scheduling information using RA-RNTI. When the RA-RNTI is mapped to the PRACH resource for transmitting the random access preamble in operation 2a-11, the UE 2a-01 that has transmitted the random access preamble by using the specific PRACH resource determines whether the RAR message is received by attempting PDCCH reception based on the corresponding RA-RNTI. That is, when the RAR message is a Figure 2A When responding to the random access preamble sent by UE 2a-01 in operation 2a-11, the RA-RNTI used in the RAR message scheduling information may include information about the transmission of operation 2a-11. In this regard, the RA-RNTI can be calculated by the following equation (3):

[0111] RA-RNTI=1+s_id+14x t_id+14x 80x f_id+14x 80x 8x ul_carrier_id...(Equation 3)

[0112] Here, s_id represents the index corresponding to the first OFDM symbol at which transmission of the random access preamble sent in operation 2a-11 starts, and may have a value of 0≤s_id<14 (i.e., the maximum number of OFDM symbols in one slot). Additionally, t_id represents the index corresponding to the first slot at which transmission of the random access preamble sent in operation 2a-11 starts, and may have a value of 0≤t_id<80 (i.e., the maximum number of slots in one system frame (20 ms)). Furthermore, f_id represents the PRACH resource on which the random access preamble sent in operation 2a-11 is transmitted on one frequency, and may have a value of 0≤f_id<8 (i.e., the maximum number of PRACHs on one frequency at the same time). Furthermore, ul_carrier_id is a factor used to distinguish whether the random access preamble is transmitted in the NUL (0 in this case) or the SUL (1 in this case) when two carriers are used in the UL of one cell.

[0113] In the current embodiment of the present disclosure, it is assumed that in operation 2a-11, UE 2a-01 receives a RAR message via the RA-RNTI corresponding to the transmitted random access preamble, but does not include the index corresponding to the random access preamble. That is, for example, UE 2a-01 may have transmitted preamble index No. 7 out of a total of 64 preamble indices, but the RAR message received from NB 2a-03 may include a response only for preamble index No. 4. Therefore, when there is a backoff indicator (BI) value received when retransmitting the random access preamble as described above, UE 2a-01 may delay the retransmission time by a random number selected according to the BI value during the backoff period 2a-61, retransmit the random access preamble in operation 2a-13, wait for a response in the RAR window 2a-53, and receive the RAR message in operation 2a-23. In this way, when there are many UEs 2a-01 performing contention-based random access, preamble transmission is distributed in time, thereby increasing the probability of random access success.

[0114] In addition, when retransmitting the random access preamble in operation 2a-13, UE 2a-01 can transmit the random access preamble using a power (power ramp) obtained by increasing the transmission power of the preamble according to the value (preamblePowerRampingStep) received from NB 2a-03, compared to the transmission power of the random access preamble transmitted in operation 2a-11. Therefore, as the number of retransmissions increases, the power continues to increase until the power reaches the maximum transmission power of UE 2a-01, and thus the probability of the signal reaching NB 2a-03 further increases.

[0115] In operation 2a-31, UE 2a-01, which has received the RAR message, transmits another message according to the various purposes described above by using the resources allocated to the RAR message. In the current embodiment of the present disclosure, the third message transmitted is referred to as Msg3 (that is, the random access preamble of operation 2a-11 or 2a-13 is referred to as Msg1, and the RAR message of operation 2a-21 is referred to as Msg2). For example, Msg3 transmitted by UE 2a-01 may include an RRCConnectionRequest message as an RRC entity message for initial access, an RRCConnectionReestablishmentRequest message for re-access, or an RRCConnectionReconfigurationComplete message for handover. Optionally, a BSR message for requesting resources may be transmitted.

[0116] When Msg3 is initially transmitted (for example, when Msg3 does not include the NB identification information previously allocated to UE 2a-01), in operation 2a-41, UE 2a-01 can receive a contention resolution message from NB 2a-03. The contention resolution message includes all the information included in Msg3 transmitted by UE 2a-01, so even when multiple UEs select the same random access preamble in operation 2a-11 or 2a-13, UE 2a-01 to receive the contention resolution message can be identified.

[0117] The reason for performing random access for each UE may vary. As described above, the reason may include initial access (including initial access for high-priority services), handover, reconfiguration due to RRC entity connection failure, etc., and in addition, random access may be used when recovering from a beam failure, wherein, in a system using a high frequency, a beam failure occurs when a transmission fails due to a mismatch between the beam direction and the direction of the UE. Therefore, since handover or beam failure indicates a situation where the UE's communication is disconnected, it may be necessary to quickly perform random access during recovery from handover or beam failure to reduce user inconvenience.

[0118] Therefore, when the UE performs random access to perform handover or recover from beam failure, the values of the backoff indicator and power ramp described above may differ from those during general random access. For example, for such purposes, the backoff indicator may use a shorter value and the power ramp may use a larger value to increase the success time and probability of random access. Thus, the parameters used to provide high priority are referred to as high priority access (HPA) parameters.

[0119] In addition, when beam recovery fails, the UE can perform recovery operations not only on the PCell but also on the SCell. Therefore, the HPA parameters can be commonly signaled to all serving cells and applied to all serving cells. The base station can configure other common random access parameters (RAR window size, power ramp size, and the above-mentioned maximum preamble transmission time) for each serving cell separately.

[0120] Figure 2B is a diagram for describing the operation of a UE according to the first embodiment of the present disclosure.

[0121] Reference Figure 2B In the current embodiment of the present disclosure, it is assumed that the UE has been connected to the base station and has been communicating with the base station in the connected mode, and it is assumed that a scenario of switching to another base station (or another cell in the same base station) is performed according to the movement of the UE.

[0122] Therefore, in operation 2b-03, the UE may receive a handover command from the source base station. When the Reconfig with Sync information element (IE) is included in the RRC Reconfiguration message of the RRC entity, the UE may receive a command to move to the corresponding base station. In addition, the RRC Reconfiguration message may include the first random access parameter and the second random access parameter.

[0123] The first random access parameter is a parameter set related to the above-mentioned HPA parameters, which is applied to all serving cells. For example, the first random access parameter may include BackoffScalingFactorHighPriorityAccess related to the backoff indicator and preamblePowerRampingStepHighPriorityAccess related to the power ramp. BackoffScalingFactorHighPriorityAccess is a value indicating the degree to which the value of the existing backoff indicator notified by signaling is scaled when the application time (for example, 1 / 2, 1 / 4 or 0 compared to the signal backoff time) is applied. For example, when the UE performs random access for handover and beam failure recovery while the backoff time notified by signaling is 10ms and the BackoffScalingFactorHighPriorityAccess is 1 / 2, the UE can delay random access by selecting a random value between 0 and 5ms (10ms x 1 / 2) during preamble retransmission, and then perform random access. In addition, according to preamblePowerRampingStepHighPriorityAccess, when performing high-priority random access, the UE can increase transmission power through preamblePowerRampingStepHighPriorityAccess instead of preamblePowerRampingStep which is a value for increasing transmission power during general random access.

[0124] In addition, the second random access parameter indicates all configurations for performing general random access, including the size of the RAR window, preamblePowerRampingStep, the maximum number of preamble transmissions, etc., and is a value set for each serving cell during CA configuration. Therefore, the UE can perform random access by applying the values configured for each serving cell while performing random access for each serving cell.

[0125] After receiving the handover command, in operation 2b-05, the UE may reset the MAC entity before attempting to access the target base station. Here, when there are first random access parameters and / or second random access parameters configured by the existing source base station, the first and / or second random access parameters are deleted from the MAC entity through the MAC reset operation, and then the RRC entity may send the first and second random access parameters configured via the handover command to the MAC entity.

[0126] In operation 2b-07, the UE may perform synchronization with the target base station and perform random access on the target base station. Here, in operation 2b-07, the UE may perform random access by using a first random access parameter and a second random access parameter received from a handover command of the RRC entity. The MAC entity of the UE cannot determine whether the RRC entity of the UE is performing handover. Therefore, the MAC entity assumes that the first random access after the MAC entity is reset is a random access for handover. Therefore, when the UE performs the first random access parameter after the MAC entity is reset and there is a first random access parameter configured from the target base station, the MAC entity of the UE determines that the first random access is an operation for handover, and when preamble retransmission is required, backoff and power ramp operations may be performed by applying the configured first random access parameter. Here, the first random access parameter is a parameter commonly applied in the entire serving cell. In addition, at this time, the UE may perform the first random access by applying the second random access parameter to the PCell in addition to the first random access parameter.

[0127] Furthermore, according to an additional embodiment of the present disclosure, when CA is configured after a handover is successful, in operation 2b-09, when the SCell is operating at a high frequency, a beam failure may occur in the SCell configured for CA, so the UE may need to perform operations to recover from the beam failure. In this case, in operation 2b-11, the UE may perform backoff and power ramp operations by applying preconfigured first random access parameters commonly applied to the entire serving cell, and may perform random access by applying second random access parameters to the SCell currently performing random access in addition to the first random access parameters.

[0128] Therefore, when random access preamble retransmission is performed according to the purpose of performing random access, the UE can quickly and successfully perform random access.

[0129] Figure 2C is a diagram for describing the operation of a UE according to the second embodiment of the present disclosure.

[0130] Reference Figure 2C In the current embodiment of the present disclosure, the UE is assumed to be in an RRC connected state. Therefore, in operation 2c-03, the UE may receive a first random access parameter from the base station via an RRCReconfiguration message of the RRC entity. For example, the UE may receive a first HPA parameter set from the RRC message. In addition, the UE may receive a 1-1st random access parameter as another set of HPA parameters via an RRCReconfiguration message or a SystemInformationBlock (SIB) message of the RRC entity. The SIB message is a message broadcast by the base station to the UE in the cell. In addition, as shown in FIG. Figure 2B As described above, regarding the second random access parameter, the UE may receive the configuration for each serving cell set via an SIB message or an RRCReconfiguration message. For example, the UE may receive the second HPA parameter set from the SIB message.

[0131] When random access is triggered in the UE in operation 2c-09, the UE may apply different HPA parameters based on the purpose in operation 2c-11.

[0132] When the UE performs random access for handover or beam failure recovery, such as Figure 2B In the example of (Type 1), the UE may apply the first random access parameter and the second random access parameter to the serving cell in operation 2c-13 and perform random access in operation 2c-19. In addition, even if the UE cannot receive scheduling from the base station despite the scheduling request continuously transmitting the maximum number of transmissions via the configured PUCCH resources, the UE may still perform random access in operation 2c-19 by applying the first random access parameter and the second random access parameter to the serving cell in operation 2c-13.

[0133] In addition, when the UE performs the RRC connection reestablishment procedure to resume connection with the PCell, the UE may perform random access in operation 2c-19 by applying the 1-1st random access parameter and the second random access parameter to the PCell in operation 2c-15.

[0134] When random access is performed for other purposes (for example, when random access is triggered via PDCCH transmission from a base station, or when random access is triggered for UL transmission with low priority), the UE may perform random access in operation 2c-19 by applying the second random access parameter only to the serving cell performing random access without applying the first random access parameter or the 1-1st random access parameter in operation 2c-17.

[0135] Figure 2D is a block diagram of a UE according to an embodiment of the present disclosure.

[0136] Reference Figure 2D , the UE includes a radio frequency (RF) processor 2d-10, a baseband processor 2d-20, a storage device 2d-30, and a controller 2d-40. However, the components of the UE are only examples, so the UE may include more than Figure 2D More or fewer components.

[0137] The RF processor 2d-10 can perform functions for sending and receiving signals through a radio channel, such as signal band conversion and amplification. That is, the RF processor 2d-10 can up-convert the baseband signal provided from the baseband processor 2d-20 into an RF band signal, and down-convert the RF band signal received through the antenna into a baseband signal. For example, the RF processor 2d-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), and an analog-to-digital converter (ADC). Although in Figure 2D Only a single antenna is shown in the figure, but the UE may include multiple antennas. The RF processor 2d-10 may include multiple RF chains. The RF processor 2d-10 may perform beamforming. For beamforming, the RF processor 2d-10 may adjust the phase and amplitude of signals transmitted or received through multiple antennas or antenna elements. The RF processor 2d-10 may perform multiple-input multiple-output (MIMO) and may receive multiple layers of data in MIMO operation.

[0138] The baseband processor 2d-20 can convert between baseband signals and bit streams based on the physical entity specifications of the system. For example, for data transmission, the baseband processor 2d-20 can generate complex symbols by encoding and modulating the transmitted bit stream. For data reception, the baseband processor 2d-20 can reconstruct the received bit stream by demodulating and decoding the baseband signal provided from the RF processor 2d-10. For example, according to the orthogonal frequency division multiplexing (OFDM) scheme, for data transmission, the baseband processor 2d-20 can generate complex symbols by encoding and modulating the transmitted bit stream, mapping the complex symbols to subcarriers, and then configuring OFDM symbols by performing an inverse fast Fourier transform (IFFT) and cyclic prefix (CP) insertion. For data reception, the baseband processor 2d-20 can segment the baseband signal provided from the RF processor 2d-10 in OFDM symbol units, reconstruct the signal mapped to the subcarriers by performing a fast Fourier transform (FFT), and then reconstruct the received bit stream by demodulating and decoding the signal.

[0139] The baseband processor 2d-20 and the RF processor 2d-10 can send and receive signals as described above. In this way, each of the baseband processor 2d-20 and the RF processor 2d-10 can also be referred to as a transmitter, a receiver, a transceiver or a communication unit. At least one of the baseband processor 2d-20 or the RF processor 2d-10 may include multiple communication modules to support a variety of different radio access technologies. At least one of the baseband processor 2d-20 or the RF processor 2d-10 may include multiple communication modules to process signals of different frequency bands. For example, different radio access technologies may include wireless local area networks (wireless LANs) (e.g., IEEE 802.11) and cellular networks (e.g., LTE). Different frequency bands may include ultra-high frequency (SHF) (e.g., 2.5 GHz and 5 GHz) bands and millimeter wave (mmWave) (e.g., 60 GHz) bands.

[0140] The storage device 2d-30 can store data used for the operation of the UE, such as basic programs, applications, and configuration information. In particular, the storage device 2d-30 can store information about wireless LAN nodes used to perform wireless communication using wireless LAN access technology. The storage device 2d-30 can provide the stored data in response to a request from the controller 2d-40.

[0141] The controller 2d-40 may control the overall operation of the UE. For example, the controller 2d-40 may send and receive signals through the baseband processor 2d-20 and the RF processor 2d-10. The controller 2d-40 may record data on the storage device 2d-30 or read data from the storage device 2d-30. To this end, the controller 2d-40 may include at least one processor. For example, the controller 2d-40 may include a communication processor (CP) for controlling communications and an application processor (AP) for controlling upper layer entities such as applications. According to an embodiment of the present disclosure, the controller 2d-40 may include a multi-connection processor 2d-42 for operating in a multi-connection mode. For example, the controller 2d-40 may control the UE to perform Figure 2B The process shown.

[0142] The controller 2d-40 according to an embodiment of the present disclosure may perform random access by applying parameters according to the type of random access performed by the UE.

[0143] According to one or more embodiments of the present disclosure, a UE can receive a random access response with the correct bandwidth while performing random access, thereby successfully performing random access with a base station. In addition, according to one or more embodiments of the present disclosure, a UE can perform random access in a hierarchical manner and retry random access according to the type of random access.

[0144] The methods according to the claims or embodiments described in the present disclosure may be implemented by hardware or a combination of hardware and software.

[0145] When the method is implemented in software, a computer-readable recording medium having one or more programs (software modules) recorded thereon may be provided. The one or more programs recorded on the computer-readable recording medium are configured to be executable by one or more processors in an electronic device. The one or more programs include instructions for executing the method according to the embodiments of the present disclosure described in the claims or detailed description.

[0146] The program (e.g., software module or software) may be stored in random access memory (RAM), nonvolatile memory including flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic disk storage, compact disk-ROM (CD-ROM), digital versatile disk (DVD), another type of optical storage device, or magnetic tape. Alternatively, the program may be stored in a storage system that includes a combination of some or all of the above storage devices. In addition, each storage device may include multiple of the above and other storage devices.

[0147] The program may also be stored in an attachable storage device accessible via a communication network (such as the Internet, an intranet, a local area network (LAN), a wireless LAN (WLAN), or a storage area network (SAN), or a combination thereof). The storage device may be connected to an apparatus according to an embodiment of the present disclosure via an external port. Another storage device on the communication network may also be connected to an apparatus performing an embodiment of the present disclosure.

[0148] In the foregoing embodiments of the present disclosure, the elements included in the present disclosure are expressed in singular or plural form, depending on the embodiment of the present disclosure. However, for ease of explanation, the singular or plural form is appropriately selected, and the present disclosure is not limited thereto. Thus, an element expressed in plural form may also be configured as a single element, and an element expressed in singular form may also be configured as a plurality of elements.

[0149] While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A method for random access in a wireless communication system, performed by a terminal, the method comprising: receiving, from a base station, BWP configuration information including an identification (ID) of each of at least one downlink (DL) bandwidth part (BWP) and at least one uplink (UL) BWP for each of at least one serving cell; as well as Perform a random access procedure on the active UL BWP of the serving cell based on the BWP configuration information, The execution of the random access process includes: In the case that the serving cell is a specific cell and the ID of the active DL BWP of the serving cell is different from the ID of the active UL BWP of the serving cell, switching the serving cell's active DL BWP to the serving cell's DL BWP having the same ID as the serving cell's active UL BWP, and performing the random access procedure on a switched DL BWP of a serving cell and an active UL BWP of a serving cell; and When the serving cell is a secondary cell (SCell), The random access procedure is performed on the active DL BWP of the specific cell and the active UL BWP of the serving cell, The specific cell is a primary cell (PCell) or a primary-secondary cell group cell.

2. The method according to claim 1, wherein The random access procedure includes a contention-based random access procedure or a non-contention-based random access procedure.

3. A method for random access in a wireless communication system, performed by a base station, the method comprising: transmitting, to the terminal, BWP configuration information including an identification (ID) of each of at least one downlink (DL) bandwidth part (BWP) and at least one uplink (UL) BWP for each of at least one serving cell, Wherein, when the serving cell is a specific cell and the ID of the active DL BWP of the serving cell is different from the ID of the active UL BWP of the serving cell, the terminal performs a random access procedure on the active UL BWP of the serving cell and the DL BWP of the serving cell switched from the active DL BWP of the serving cell, wherein the switched DL BWP has the same ID as the ID of the active UL BWP of the serving cell, Wherein, when the serving cell is a secondary cell (SCell), the random access procedure is performed by the terminal on the active DL BWP of the specific cell and the active UL BWP of the serving cell, The specific cell is a primary cell (PCell) or a primary-secondary cell group cell.

4. The method according to claim 3, wherein: The random access procedure includes a contention-based random access procedure or a non-contention-based random access procedure.

5. A terminal for performing random access in a wireless communication system, the terminal comprising: transceiver; as well as At least one processor, coupled to the transceiver, and configured to: receiving, from a base station, BWP configuration information including an identification (ID) of each of at least one downlink (DL) bandwidth part (BWP) and at least one uplink (UL) BWP for each of at least one serving cell, and Perform a random access procedure on the active UL BWP of the serving cell based on the BWP configuration information, The execution of the random access process includes: In the case that the serving cell is a specific cell and the ID of the active DL BWP of the serving cell is different from the ID of the active UL BWP of the serving cell, switching the serving cell's active DL BWP to the serving cell's DL BWP having the same ID as the serving cell's active UL BWP, and performing the random access procedure on a switched DL BWP of a serving cell and an active UL BWP of a serving cell; and When the serving cell is a secondary cell (SCell): The random access procedure is performed on the active DL BWP of the specific cell and the active UL BWP of the serving cell, The specific cell is a primary cell (PCell) or a primary-secondary cell group cell. The terminal according to claim 5 , wherein: The random access procedure includes a contention-based random access procedure or a non-contention-based random access procedure.

7. A base station for performing random access in a wireless communication system, the base station comprising: transceiver; as well as At least one processor, coupled to the transceiver, and configured to: transmitting, to the terminal, BWP configuration information including an identification (ID) of each of at least one downlink (DL) bandwidth part (BWP) and at least one uplink (UL) BWP for each of at least one serving cell, Wherein, when the serving cell is a specific cell and the ID of the active DL BWP of the serving cell is different from the ID of the active UL BWP of the serving cell, the terminal performs a random access procedure on the active UL BWP of the serving cell and the DL BWP of the serving cell switched from the active DL BWP of the serving cell, wherein the switched DL BWP has the same ID as the ID of the active UL BWP of the serving cell, Wherein, when the serving cell is a secondary cell (SCell), the random access procedure is performed by the terminal on the active DL BWP of the specific cell and the active UL BWP of the serving cell, The specific cell is a primary cell (PCell) or a primary-secondary cell group cell. The base station according to claim 7 , wherein: The random access procedure includes a contention-based random access procedure or a non-contention-based random access procedure.

9. A computer-readable medium storing instructions, which, when executed by a computer, cause the computer to implement the method of claim 1 or claim 3.

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