KR20220022831A - Method and apparatus of communication for user equipment with reduced complexity in wireless communication system - Google Patents

Abstract

The present disclosure relates to a communication technique which converges a 5G communication system for supporting a higher data transfer rate after a 4G system with an IoT technology, and a system thereof. The present disclosure can be applied to intelligent services (for example, smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail business, security, and safety related services, etc.) based on a 5G communication technology and an IoT-related technology. The present disclosure relates to efficient communication method and device for a low complexity terminal using a half-duplex communication method in a wireless communication system. A method in which a low-complexity terminal performs a random access procedure in a wireless communication system according to an embodiment of the present disclosure, includes a process of receiving configuration information including resource information for random access in the low complexity terminal from a base station; a process of transmitting capability information of the low complexity terminal including whether half-duplex communication is supported to the base station; a process of, when the random access is executed, checking whether there is a random access opportunity overlapping with a radio frequency (RF) switching gap in a time domain; and a process of, when there is the random access opportunity overlapping with the RF switching gap, based on the resource information for the received random access, excluding the overlapping random access transmission opportunity and then performing the random access procedure with the base station at the next random access opportunity.

Description

Communication method and apparatus for a low-complexity terminal in a wireless communication system

The present disclosure relates to a communication method and apparatus for a low-complexity terminal in a wireless communication system, and more particularly, to a communication method and apparatus when the low-complexity terminal performs a half-duplex operation.

Efforts are being made to develop an improved 5G communication system or pre-5G communication system in order to meet the increasing demand for wireless data traffic after commercialization of the 4G communication system. For this reason, the 5G communication system or the pre-5G communication system is called a 4G network after (Beyond 4G Network) communication system or an LTE system after (Post LTE) system. The 5G communication system defined by 3GPP is called the New Radio (NR) system.

In order to achieve a high data rate, the 5G communication system is being considered for implementation in a very high frequency (mmWave) band (eg, such as a 60 gigabyte (60 GHz) band). In order to alleviate the path loss of radio waves and increase the propagation distance of radio waves in the ultra-high frequency band, in the 5G communication system, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) are used. ), array antenna, analog beam-forming, and large scale antenna techniques have been discussed and applied to the NR system.

In addition, for network improvement of the system, in the 5G communication system, an evolved small cell, an advanced small cell, a cloud radio access network (cloud radio access network: cloud RAN), an ultra-dense network (ultra-dense network) , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and reception interference cancellation Technology development is underway.

In addition, in the 5G system, the advanced coding modulation (ACM) methods FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), and advanced access technologies FBMC (Filter Bank Multi Carrier), NOMA (non-orthogonal multiple access), and sparse code multiple access (SCMA) are being developed.

On the other hand, the Internet is evolving from a human-centered connection network where humans create and consume information to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. Internet of Everything (IoE) technology, which combines big data processing technology through connection with cloud servers, etc. with IoT technology, is also emerging. In order to implement IoT, technology elements such as sensing technology, wired and wireless communication and network infrastructure, service interface technology, and security technology are required. , M2M), and MTC (Machine Type Communication) are being studied. In the IoT environment, an intelligent IT (Internet Technology) service that collects and analyzes data generated from connected objects and creates new values in human life can be provided. IoT is a field of smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart home appliance, advanced medical service, etc. can be applied to

Accordingly, various attempts are being made to apply the 5G communication system to the IoT network. For example, 5G communication such as sensor network, machine to machine communication (M2M), and machine type communication (MTC) is being implemented by techniques such as beam forming, MIMO, and array antenna. The application of cloud radio access network (cloud RAN) as the big data processing technology described above can be said to be an example of convergence of 5G technology and IoT technology.

In addition, 3GPP discusses the NR RedCap (Reduced Capability, Low Complexity) terminal standard that enables data transmission and reception by accessing the 5G communication system while reducing the complexity of the terminal to support technologies such as sensors, surveillance cameras, and smart watches. is starting

The present disclosure provides an efficient communication method and apparatus for a terminal using a half-duflex communication method in a wireless communication system.

The present disclosure provides a resource allocation method and apparatus for a random access procedure in a terminal using a half-duplex communication method in a wireless communication system.

The present disclosure provides an efficient random access method and apparatus for a low-complexity terminal using a half-duplex communication scheme in a wireless communication system.

A method for a low-complexity terminal to perform a random access procedure in a wireless communication system according to an embodiment of the present disclosure includes: receiving configuration information including resource information for random access in the low-complexity terminal from a base station; The process of transmitting the capability information of the low-complexity terminal including whether or not half-duplex communication is supported, and when performing the random access, a random access opportunity overlapping the RF (radio frequency) switching gap in the time domain Checking whether there is When there is a random access opportunity overlapping the RF switching gap, the base station and the random access procedure at the next random access opportunity excluding the overlapping random access transmission opportunity based on the received resource information for random access It includes the process of performing

In addition, in the wireless communication system according to an embodiment of the present disclosure, the low-complexity terminal receives configuration information including resource information for random access in the low-complexity terminal from the base station through a transceiver and the transceiver, and through the transceiver Transmits the capability information of the low-complexity terminal including whether half-duplex communication is supported to the base station, and when performing the random access, it is checked whether there is a random access opportunity overlapping the RF switching gap in the time domain, and the RF switching When there is a gap and the overlapping random access opportunity, based on the received resource information for random access, the random access procedure is performed with the base station at the next random access opportunity excluding the overlapping random access transmission opportunity through the transceiver includes a processor that

In addition, a method for a base station to perform a random access procedure in a wireless communication system according to an embodiment of the present disclosure includes a process of transmitting configuration information including resource information for random access from a low complexity terminal, and half-duplex communication from the low complexity terminal The process of receiving the capability information of the low-complexity terminal including whether to support and when there is a random access opportunity overlapping the RF switching gap, based on the transmitted resource information for random access, the overlapping random access and performing the random access procedure with the low complexity terminal at the next random access opportunity excluding the opportunity.

In addition, in a wireless communication system according to an embodiment of the present disclosure, a base station transmits configuration information including resource information for random access in a low-complexity terminal through a transceiver and the transceiver, and half-duplex from the low-complexity terminal through the transceiver Receives capability information of the low-complexity terminal including whether communication is supported, and when there is a random access opportunity overlapping an RF switching gap through the transceiver, based on the transmitted resource information for random access, the and a processor for performing the random access procedure with the low-complexity terminal at the next random access opportunity excluding the overlapping random access opportunity.

1 is a diagram illustrating a basic structure of a time-frequency domain, which is a radio resource domain, in a wireless communication system to which the present disclosure is applied.
2 is a diagram illustrating a slot structure considered in a wireless communication system to which the present disclosure is applied.
3 is a diagram illustrating a synchronization signal block considered in a wireless communication system to which the present disclosure is applied.
4 is a diagram illustrating transmission cases of a synchronization signal block in a frequency band of 6 GHz or less considered in a wireless communication system to which the present disclosure is applied.
5 is a diagram illustrating transmission cases of a synchronization signal block in a frequency band of 6 GHz or higher considered in a wireless communication system to which the present disclosure is applied.
6 is a diagram illustrating transmission cases of a synchronization signal block according to a subcarrier interval within 5 ms in a wireless communication system to which the present disclosure is applied.
7 is a diagram illustrating a four-step random access procedure in a wireless communication system to which the present disclosure is applied.
8 is a diagram illustrating a case in which a low-complexity terminal supporting half-duplex communication cannot transmit a random access preamble on a valid random access occasion in a wireless communication system to which the present disclosure is applied.
9 is a diagram illustrating a relationship between a synchronization signal block and an effective random access occasion in a wireless communication system to which the present disclosure is applied.
10A and 10B are diagrams illustrating an example of a random access resource allocation method for a low complexity terminal according to an embodiment of the present disclosure.
11 is a diagram illustrating a method for a low-complexity terminal to perform a random access procedure in a wireless communication system according to an embodiment of the present disclosure.
12 is a diagram illustrating a method for a base station to perform a random access procedure for a low complexity terminal in a wireless communication system according to an embodiment of the present disclosure.
13 is a block diagram of a terminal according to an embodiment of the present disclosure.
14 is a block diagram of a base station according to an embodiment of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

In describing the embodiments, descriptions of technical contents that are well known in the technical field to which the present disclosure pertains and are not directly related to the present disclosure will be omitted. This is to more clearly convey the gist of the present disclosure without obscuring the gist of the present disclosure by omitting unnecessary description.

For the same reason, some components are exaggerated, omitted, or schematically illustrated in the accompanying drawings. In addition, the size of each component does not fully reflect the actual size. In each figure, the same or corresponding elements are assigned the same reference numerals.

Advantages and features of the present disclosure, and a method for achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments described below, but may be implemented in various different forms, and only the present embodiments allow the present disclosure to be complete, and those of ordinary skill in the art to which the present disclosure pertains. It is provided to fully inform the scope of the technical idea, and the present disclosure is only defined by the scope of the claims. Like reference numerals refer to like elements throughout. In addition, in the description of the present disclosure, if it is determined that a detailed description of a related function or configuration may unnecessarily obscure the subject matter of the present disclosure, the detailed description thereof will be omitted. In addition, the terms to be described later are terms defined in consideration of functions in the present disclosure, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

Hereinafter, the base station, as a subject performing resource allocation of the terminal, is at least one of gNode B, eNode B, Node B, BS (Base Station), AP (Access Point), radio access unit, base station controller, or a node on the network. can The terminal may be at least one of a user equipment (UE), a mobile station (MS), a terminal, a cellular phone, a smart phone, a smart watch, a wearable device, a computer, and various multimedia devices capable of performing a communication function. In the beginning, a downlink (DL) is a wireless transmission path of a signal transmitted from a base station to a terminal, and an uplink (UL) is a wireless transmission path of a signal transmitted from the terminal to a flag station. In addition, although LTE or LTE-A system may be described below as an example, embodiments of the present disclosure may be applied to other communication systems having a similar technical background or channel shape. For example, 5G mobile communication technology (5G, new radio, NR) developed after LTE-A may be included in this, and 5G below may be a concept including existing LTE, LTE-A and other similar services. there is. In addition, the present disclosure may be applied to other communication systems through some modifications within a range that does not significantly deviate from the scope of the present disclosure as judged by a person having skilled technical knowledge.

At this time, it will be understood that each block of the flowchart diagrams and combinations of the flowchart diagrams may be executed by computer program instructions. These computer program instructions may be embodied in a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, such that the instructions, executed by the processor of the computer or other programmable data processing equipment, are described in the flowchart block(s). It creates a means to perform functions. These computer program instructions may also be stored in a computer-usable or computer-readable memory that may direct a computer or other programmable data processing equipment to implement a function in a particular manner, and thus the computer-usable or computer-readable memory. It is also possible that the instructions stored in the flowchart block(s) produce an article of manufacture containing instruction means for performing the function described in the flowchart block(s). The computer program instructions may also be mounted on a computer or other programmable data processing equipment, such that a series of operational steps are performed on the computer or other programmable data processing equipment to create a computer-executed process to create a computer or other programmable data processing equipment. It is also possible that instructions for performing the processing equipment provide steps for performing the functions described in the flowchart block(s).

Additionally, each block may represent a module, segment, or portion of code that includes one or more executable instructions for executing the specified logical function(s). It should also be noted that, in some alternative embodiments, it is also possible for the functions mentioned in the blocks to occur out of order. For example, two blocks shown one after another may in fact be performed substantially simultaneously, or it is possible that the blocks are sometimes performed in the reverse order according to the corresponding function.

At this time, the term '~ unit' used in this embodiment means software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and '~ unit' refers to what roles carry out However, '-part' is not limited to software or hardware. '~' may be configured to reside on an addressable storage medium or may be configured to refresh one or more processors. Accordingly, as an example, '~' indicates components such as software components, object-oriented software components, class components, and task components, and processes, functions, properties, and procedures. , subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided in the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. In addition, components and '~ units' may be implemented to play one or more CPUs in a device or secure multimedia card. Also, in an embodiment, '~ unit' may include one or more processors.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Hereinafter, the embodiments of the present disclosure will be described by taking the IoT service (IWSN, Surveillance camera, wearable, etc.) as an example for the method and apparatus proposed in the embodiments of the present disclosure, but it is not limited to each embodiment and is not applied. It may be possible to utilize all or a combination of one or more embodiments for a random access method corresponding to another additional service and a method for repetitive transmission of a random access channel preamble. Accordingly, the embodiments of the present disclosure may be applied through some modifications within a range that does not significantly deviate from the scope of the present disclosure as judged by a person having skilled technical knowledge (ie, those skilled in the art).

In addition, in the description of the present disclosure, if it is determined that a detailed description of a related function or configuration may unnecessarily obscure the subject matter of the present disclosure, the detailed description thereof will be omitted. In addition, the terms to be described later are terms defined in consideration of functions in the present disclosure, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

A wireless communication system, for example, 3GPP's HSPA (High Speed Packet Access), LTE (Long Term Evolution or E-UTRA (Evolved Universal Terrestrial Radio Access)), LTE-Advanced (LTE-A), LTE-Pro, 3GPP2 HRPD (High Rate Packet Data), UMB (Ultra Mobile Broadband), and IEEE 802.16e, such as communication standards such as broadband wireless broadband wireless providing high-speed, high-quality packet data service It is evolving into a communication system.

In the LTE system, which is a representative example of a broadband wireless communication system, an Orthogonal Frequency Division Multiplexing (OFDM) scheme is employed in downlink (DL), and Single Carrier Frequency Division Multiple Access (SC-FDMA) in uplink (UL). method is being adopted. The uplink refers to a radio link through which the terminal transmits data or control signals to the base station, and the downlink refers to a radio link through which the base station transmits data or control signals to the user equipment. In addition, in the above-described multiple access method, the data or control information of each user is divided by allocating and operating the time-frequency resources to which the data or control information is transmitted for each user, so that the time-frequency resources do not overlap with each other, that is, orthogonality is established. make it possible

The 5G communication system, which is a communication system after LTE, must support services that simultaneously satisfy various requirements so that various requirements of users and service providers can be freely reflected. Services considered for the 5G communication system include enhanced mobile broadband (eMBB), massive machine type communication (mMTC), ultra reliability low latency communication (URLLC), etc. There is this.

eMBB aims to provide more improved data transfer rates than the data transfer rates supported by existing LTE, LTE-A or LTE-Pro. For example, in the 5G communication system, the eMBB should be able to provide a maximum data rate of 20 Gbps in the downlink and a maximum data rate of 10 Gbps in the uplink from the viewpoint of one base station. In addition, the 5G communication system must provide the maximum transmission speed and at the same time provide the increased user perceived data rate of the terminal. In order to satisfy such a requirement, it may be required to improve various transmission/reception technologies, including a more advanced multi-antenna (multi input multi output, MIMO) transmission technology. In addition, in the LTE system, signals are transmitted using a transmission bandwidth of up to 20 MHz in the 2 GHz band, whereas the 5G communication system uses a frequency bandwidth wider than 20 MHz in the frequency band of 3 to 6 GHz or 6 GHz or more, so the data transmission rate required by the 5G communication system can satisfy

At the same time, mMTC is being considered to support application services such as the Internet of Thing (IoT) in the 5G communication system. In order to efficiently provide the Internet of Things, mMTC requires access support for large-scale terminals within a cell, enhancement of terminal coverage, improved battery life, and reduction of terminal cost. Since the Internet of Things is attached to various sensors and various devices to provide communication functions, it must be able to support a large number of terminals (eg, 1,000,000 terminals/km ² ) within a cell. In addition, due to the characteristics of the service, the terminal supporting mMTC is highly likely to be located in a shaded area that the cell cannot cover, such as the basement of a building, so it requires wider coverage compared to other services provided by the 5G communication system. A terminal supporting mMTC is typically composed of a low-cost terminal, and since it is difficult to frequently exchange the battery of the terminal, a very long battery life time, such as about 10 to 15 years, may be required.

Finally, in the case of URLLC, it is a cellular-based wireless communication service used for a specific purpose (mission-critical). For example, remote control of a robot or machinery, industrial automation, unmaned aerial vehicle, remote health care, emergency situations A service used for an emergency alert, etc. may be considered. Therefore, the communication provided by URLLC must provide very low latency and very high reliability. For example, a service supporting URLLC must satisfy the air interface latency of less than 0.5 milliseconds, and at the same time must satisfy the requirement of a packet error rate of 10 ^-5 or less. Therefore, for a service supporting URLLC, the 5G system must provide a smaller transmit time interval (TTI) than other services, and at the same time must allocate a wide resource in a frequency band to secure the reliability of the communication link.

The three services of the 5G communication system (hereinafter interchangeable with the 5G system), ie, eMBB, URLLC, and mMTC, can be multiplexed and transmitted in one system. In this case, different transmission/reception techniques and transmission/reception parameters may be used between services to satisfy different requirements of each service.

Hereinafter, the frame structure of the 5G system will be described in more detail with reference to the drawings. Hereinafter, the wireless communication system to which the present disclosure is applied will be described by taking the configuration of a 5G system as an example for convenience of description, but embodiments of the present disclosure in the same or similar manner in 5G or higher systems or other communication systems to which the present disclosure is applicable can be applied.

1 is a diagram illustrating a basic structure of a time-frequency domain, which is a radio resource domain, in a wireless communication system to which the present disclosure is applied.

(일례로 12) 개의 연속된 RE들은 하나의 자원 블록(resource block, RB, 104)을 구성할 수 있다. 또한, 시간 영역에서 서브프레임 당 심볼 수를 나타내는

개의 연속된 OFDM 심볼들은 하나의 서브프레임(subframe, 110)을 구성할 수 있다. 5G 시스템에서 자원 구조에 대한 보다 구체적인 설명은 TS 38.211 section 4 규격을 참조할 수 있다.1 , the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. A basic unit of a resource in the time and frequency domain is a resource element (RE, 101), which is one Orthogonal Frequency Division Multiplexing (OFDM) symbol (or discrete Fourier transform spread OFDM (DFT-s-OFDM) symbol) on the time axis. (102) and may be defined as one subcarrier (subcarrier, 103) on the frequency axis. Representing the number of subcarriers per resource block (RB) in the frequency domain

(For example, 12) consecutive REs may constitute one resource block (resource block, RB, 104). In addition, indicating the number of symbols per subframe in the time domain

The consecutive OFDM symbols may constitute one subframe 110 . For a more detailed description of the resource structure in the 5G system, refer to the TS 38.211 section 4 standard.

2 is a diagram illustrating a slot structure considered in a wireless communication system to which the present disclosure is applied.

))=14). 1개의 서브프레임(201)은 하나 또는 다수개의 슬롯(202, 203)으로 구성될 수 있으며, 1개의 서브프레임(201)당 슬롯(202, 203)의 개수는 부반송파 간격에 대한 설정 값인 μ(204, 205)에 따라 다를 수 있다.2 shows an example of a structure of a frame 200 , a subframe 201 , and a slot 202 . One frame 200 may be defined as 10 ms. One subframe 201 may be defined as 1 ms, and thus, one frame 200 may consist of a total of 10 subframes 201 . In addition, one slot 202, 203 may be defined as 14 OFDM symbols (that is, the number of symbols per slot (

))=14). One subframe 201 may consist of one or a plurality of slots 202 and 203, and the number of slots 202 and 203 per one subframe 201 is μ(204), which is a set value for the subcarrier interval. , 205).

)가 달라질 수 있고, 이에 따라 1개의 프레임 당 슬롯 수(

)가 달라질 수 있다. 각 부반송파 간격 설정 μ에 따른

및

는 하기의 표 1로 정의될 수 있다.In the example of FIG. 2 , the slot structure in the case of μ=0 (204) and μ=1 (205) is shown as the subcarrier spacing setting value. When μ = 0 (204), one subframe 201 may consist of one slot 202, and when μ = 1 (205), one subframe 201 may consist of two slots ( 203) can be configured. That is, the number of slots per subframe (

) may vary, and accordingly, the number of slots per frame (

) may be different. According to each subcarrier spacing setting μ

and

may be defined in Table 1 below.

[Table 1]

In the 5G wireless communication system, a synchronization signal block (synchronization signal block, SSB, SS block, SS/PBCH block, etc. may be mixed) for initial access of the terminal may be transmitted, and synchronization The signal block may include a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH). In the initial access phase in which the terminal accesses the system, the terminal first acquires downlink time and frequency domain synchronization from a synchronization signal through cell search and obtains a cell ID acquire The synchronization signal includes PSS and SSS. In addition, the terminal receives the PBCH for transmitting a master information block (MIB) from the base station, and acquires system information related to transmission and reception, such as system bandwidth or related control information, and basic parameter values. Based on this information, the UE may perform decoding on a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) to obtain a system information block (SIB). Thereafter, the terminal exchanges identification-related information between the base station and the terminal through a random access step and initially accesses the network through steps such as registration and authentication.

Hereinafter, the cell initial access operation procedure of the 5G wireless communication system will be described in more detail with reference to the drawings.

The synchronization signal is a standard signal for cell search, and is transmitted by applying a subcarrier spacing suitable for a channel environment such as phase noise for each frequency band. The 5G base station may transmit a plurality of synchronization signal blocks according to the number of analog beams to be operated. For example, PSS and SSS may be mapped over 12 RBs and transmitted, and PBCH may be mapped over 24 RBs and transmitted. Hereinafter, a structure in which a synchronization signal and a PBCH are transmitted in a 5G communication system will be described.

3 is a diagram illustrating a synchronization signal block considered in a wireless communication system to which the present disclosure is applied.

According to FIG. 3 , a synchronization signal block (SS block) 300 includes a PSS 301 , an SSS 303 , and a Broadcast Channel (PBCH) 302 .

As shown in FIG. 3 , the synchronization signal block 300 is mapped to four OFDM symbols 304 in the time axis. The PSS 301 and the SSS 303 may be transmitted in 12 RBs 305 on the frequency axis and the first and third OFDM symbols on the time axis, respectively. In the 5G system, for example, a total of 1008 different cell IDs may be defined, the PSS 301 may have three different values according to the physical layer ID of the cell, and the SSS 303 may have 336 different cell IDs. can have a value. The UE may acquire one of (336X3=)1008 cell IDs by a combination of the PSS 301 and the SSS 303 through detection. This can be expressed by Equation 1 below.

[Equation 1]

Here, N ⁽¹⁾ _ID can be estimated from the SSS 303 and has a value between 0 and 335. N ⁽²⁾ _ID may be estimated from the PSS 301 and has a value between 0 and 2. The UE may estimate the N ^cell _ID value, which is the cell ID, by using a combination of N ⁽¹⁾ _ID and N ⁽²⁾ _ID .

The PBCH 302 has 24 RBs 306 on the frequency axis and 6 RBs 307 and 308 on both sides except for 12 RBs among the SSS 303 being transmitted in the second to fourth OFDM symbols of the SS block on the time axis. It can be transmitted from the included resource. Various system information called MIB may be transmitted in the PBCH 302 , and more specifically, the MIB may include information as shown in Table 2 below, PBCH payload and PBCH demodulation reference singal (DMRS). contains the following additional information. For a more detailed description of the MIB in the 5G system, reference may be made to the TS 38.331 standard.

[Table 2]

- Synchronization signal block information: The offset of the frequency domain of the synchronization signal block is indicated through 4 bits (ssb-SubcarrierOffset) in the MIB. The index of the synchronization signal block including the PBCH may be indirectly obtained through decoding of the PBCH DMRS and PBCH. More specifically, in the frequency band below 6 GHz, 3 bits obtained through decoding of the PBCH DMRS indicate the synchronization signal block index, and in the frequency band above 6 GHz, 3 bits obtained through decoding of the PBCH DMRS and the PBCH payload include A total of 6 bits including 3 bits obtained in PBCH decoding may indicate the synchronization signal block index including the PBCH.

- PDCCH (physical downlink control channel) information: 1 bit (subCarrierSpacingCommon) in the MIB indicates the subcarrier spacing of the common downlink control channel, and 8 bits (pdcch-ConfigSIB1) through CORESET (control resource set) and search area ( time-frequency resource configuration information of the search space (SS).

- SFN (system frame number): 6 bits (systemFrameNumber) in the MIB are used to indicate a part of the SFN. The LSB (Least Significant Bit) 4 bits of the SFN are included in the PBCH payload so that the UE can indirectly obtain it through PBCH decoding.

- Timing information in a radio frame: 1 bit (half frame) included in the above-described synchronization signal block index and PBCH payload and obtained through PBCH decoding, the UE indicates that the synchronization signal block is the first of the radio frame It can be indirectly checked whether it is transmitted in the second or second half frame.

Since the transmission bandwidth (12RB 305) of the PSS 301 and the SSS 303 and the transmission bandwidth (24RB 306) of the PBCH 302 are different from each other, the PSS 301 within the transmission bandwidth of the PBCH 302 is In the first OFDM symbol transmitted, 6 RBs 307 and 308 exist on both sides of the PSS 301 except for 12 RBs, and the area may be used to transmit other signals or may be empty.

All synchronization signal blocks may be transmitted using the same analog beam. That is, the PSS 301 , the SSS 303 , and the PBCH 302 may all be transmitted through the same beam. Since the analog beam has a characteristic that cannot be applied differently on the frequency axis, the same analog beam is applied to all frequency axis RBs within a specific OFDM symbol to which the specific analog beam is applied. That is, all four OFDM symbols in which the PSS 301 , the SSS 303 , and the PBCH 302 are transmitted may be transmitted using the same analog beam.

4 is a diagram illustrating various transmission cases of a synchronization signal block in a frequency band of 6 GHz or less considered in a communication system to which the present disclosure is applied.

In the 5G communication system, in a frequency band of 6 GHz or less, a subcarrier spacing of 15 kHz (420) and a subcarrier spacing of 30 kHz (430, 440) may be used for synchronization signal block transmission. At the 15 kHz subcarrier interval, there is one transmission case for the synchronization signal block (Case #1 (401)), and at the 30 kHz subcarrier interval there are two transmission cases for the synchronization signal block (Case #2 (402) and Case #3 (Case #2 (402) and Case #3) 403)) may exist.

In FIG. 4, in case #1 (401) at subcarrier spacing of 15 kHz (420), the synchronization signal block is maximum within 1 ms (404) time (or, when 1 slot consists of 14 OFDM symbols, it corresponds to 1 slot length). Two can be transmitted. In the example of FIG. 4, synchronization signal block #0 407 and synchronization signal block #1 408 are shown. For example, the synchronization signal block #0 407 may be mapped to 4 consecutive symbols from the 3rd OFDM symbol, and the synchronization signal block #1 (408) may be mapped to 4 consecutive symbols from the 9th OFDM symbol. can be mapped.

Different analog beams may be applied to the synchronization signal block #0 (407) and the synchronization signal block # 1 (408). In addition, the same beam may be applied to all 3rd to 6th OFDM symbols to which synchronization signal block #0 407 is mapped, and the same beam may be applied to all 9th to 12th OFDM symbols to which synchronization signal block #1 (408) is mapped. can In the 7th, 8th, 13th, and 14th OFDM symbols to which the synchronization signal block is not mapped, an analog beam may be freely determined under the determination of the base station which beam will be used.

In FIG. 4, in case #2 (402) at subcarrier interval of 30 kHz (430), the synchronization signal block is within 0.5 ms (405) time (or, if 1 slot consists of 14 OFDM symbols, it corresponds to 1 slot length) A maximum of two may be transmitted, and accordingly, a maximum of four synchronization signal blocks may be transmitted within 1 ms (or, when 1 slot is configured with 14 OFDM symbols, corresponding to a length of 2 slots). In the example of FIG. 4 , the synchronization signal block #0 (409), the synchronization signal block #1 (410), the synchronization signal block #2 (411), and the synchronization signal block #3 (412) are 1 ms (ie, two slots) The case of transmission in time is shown. At this time, the synchronization signal block #0 (409) and the synchronization signal block #1 (410) may be mapped from the 5th OFDM symbol and the 9th OFDM symbol of the first slot, respectively, and the synchronization signal block #2 (411) and Synchronization signal block #3 (412) may be mapped from the third OFDM symbol and the seventh OFDM symbol of the second slot, respectively.

Different analog beams may be applied to the synchronization signal block #0 (409), the synchronization signal block #1 (410), the synchronization signal block #2 (411), and the synchronization signal block #3 (412). And the 5th to 8th OFDM symbols of the first slot in which the synchronization signal block #0 (409) is transmitted, the 9th to 12th OFDM symbols of the first slot in which the synchronization signal block #1 (410) is transmitted, and the synchronization signal block #2 The same analog beam may be applied to the 3rd to 6th symbols of the second slot in which 411 is transmitted and the 7th to 10th symbols of the second slot in which the synchronization signal block #3 (412) is transmitted. In OFDM symbols to which a synchronization signal block is not mapped, an analog beam may be freely determined under the determination of the base station which beam will be used.

In FIG. 4, in case #3 (403) at subcarrier spacing of 30 kHz (440), the synchronization signal block is within 0.5 ms (406) time (or if 1 slot consists of 14 OFDM symbols, it corresponds to 1 slot length) A maximum of two may be transmitted, and accordingly, a maximum of four synchronization signal blocks may be transmitted within 1 ms (or, when 1 slot is configured with 14 OFDM symbols, corresponding to a length of 2 slots). In the example of FIG. 4 , the synchronization signal block #0 (413), the synchronization signal block #1 (414), the synchronization signal block #2 (415), and the synchronization signal block #3 (416) are 1 ms (ie, two slots) Transmission in time is shown. At this time, the synchronization signal block #0 (413) and the synchronization signal block #1 (414) may be mapped from the 3rd OFDM symbol and the 9th OFDM symbol of the first slot, respectively, and are synchronized with the synchronization signal block #2 (415). Signal block #3 (416) may be mapped from the third OFDM symbol and the ninth OFDM symbol of the second slot, respectively.

Different analog beams may be used for the synchronization signal block #0 (413), the synchronization signal block #1 (414), the synchronization signal block #2 (415), and the synchronization signal block #3 (416). As described in the above examples, the same analog beam may be used in all four OFDM symbols in which each synchronization signal block is transmitted, and which beam is used in OFDM symbols to which the synchronization signal block is not mapped is freely determined by the base station. can be decided.

5 is a diagram illustrating transmission cases of a synchronization signal block in a frequency band of 6 GHz or higher considered in a wireless communication system to which the present disclosure is applied.

In the 5G communication system, in the frequency band of 6 GHz or higher, the sub-carrier spacing of 120 kHz (530) as in the example of case # 4 (510) and the sub-carrier spacing of 240 kHz (540) as in the example of case # 5 (520) are used for synchronization signal block transmission. can be used

In case #4 (510) with subcarrier spacing of 120 kHz (530), a maximum of 4 synchronization signal blocks are transmitted within 0.25 ms (501) time (or if 1 slot consists of 14 OFDM symbols, it corresponds to 2 slots length) can be In the example of FIG. 5, the synchronization signal block #0 (503), the synchronization signal block #1 (504), the synchronization signal block #2 (505), and the synchronization signal block #3 (506) at 0.25 ms (ie, two slots) The transmission case is shown. At this time, the synchronization signal block #0 503 and the synchronization signal block #1 504 may be mapped to four consecutive symbols from the 5th OFDM symbol of the first slot, respectively, and consecutive from the 9th OFDM symbol. may be mapped to 4 symbols, and synchronization signal block #2 505 and synchronization signal block #3 506 may each be mapped to 4 consecutive symbols from the 3rd OFDM symbol of the second slot, It may be mapped to 4 consecutive symbols from the 7th OFDM symbol.

As described in the above embodiment, the synchronization signal block #0 (503), the synchronization signal block #1 (504), the synchronization signal block #2 (505), and the synchronization signal block #3 (506) each have different analog beams. can be used In addition, the same analog beam may be used in all four OFDM symbols to which each synchronization signal block is transmitted, and which beam will be used in OFDM symbols to which the synchronization signal block is not mapped may be freely determined under the determination of the base station.

In case #5 (520) at subcarrier spacing of 240 kHz (540), a maximum of 8 synchronization signal blocks within 0.25 ms (502) time (or, when 1 slot consists of 14 OFDM symbols, corresponds to a length of 4 slots) can be transmitted. In the example of Figure 5, synchronization signal block #0 (507), synchronization signal block #1 (508), synchronization signal block #2 (509), synchronization signal block #3 (510), synchronization signal block #4 (511), A case is shown in which synchronization signal block #5 (512), synchronization signal block #6 (513), and synchronization signal block #7 (514) are transmitted in 0.25 ms (ie 4 slots). At this time, the synchronization signal block #0 (507) and the synchronization signal block #1 (508) may be mapped to four consecutive symbols from the ninth OFDM symbol of the first slot, respectively, and consecutive from the thirteenth OFDM symbol. may be mapped to 4 symbols, and synchronization signal block #2 (509) and synchronization signal block #3 (510) may each be mapped to 4 consecutive symbols from the 3rd OFDM symbol of the second slot, May be mapped to 4 consecutive symbols from the 7th OFDM symbol, and synchronization signal block #4 (511), synchronization signal block #5 (512), and synchronization signal block #6 (513) are 5 of the third slot, respectively. May be mapped to four consecutive symbols from the th OFDM symbol, may be mapped to four consecutive symbols from the ninth OFDM symbol, and may be mapped to four consecutive symbols from the thirteenth OFDM symbol, The synchronization signal block #7 (514) may be mapped to four consecutive symbols from the third OFDM symbol of the fourth slot.

As described in the above embodiment, the synchronization signal block #0 (507), the synchronization signal block #1 (508), the synchronization signal block #2 (509), the synchronization signal block #3 (510), the synchronization signal block #4 ( 511), the synchronization signal block #5 (512), the synchronization signal block #6 (513), and the synchronization signal block #7 (514) may use different analog beams, respectively. In addition, the same analog beam may be used in all four OFDM symbols in which each synchronization signal block is transmitted, and in OFDM symbols to which a synchronization signal block is not mapped, a beam may be freely determined by the base station to be used.

6 is a diagram illustrating transmission cases of a synchronization signal block according to a subcarrier interval within 5 ms in a wireless communication system to which the present disclosure is applied. In the 5G communication system, the synchronization signal block may be periodically transmitted in units of 5 ms (corresponding to 5 subframes or half frames, 610).

In a frequency band of 3 GHz or less, a maximum of four synchronization signal blocks may be transmitted within 5 ms (610) time. Up to 8 synchronization signal blocks can be transmitted in a frequency band greater than 3 GHz and less than or equal to 6 GHz. Up to 64 blocks of synchronization signals can be transmitted in the frequency band above 6 GHz. As described above, the subcarrier spacing of 15 kHz and 30 kHz may be used at frequencies below 6 GHz.

In the example of FIG. 6, in case #1 (401) at a subcarrier interval of 15 kHz consisting of one slot of FIG. 4, a synchronization signal block in a frequency band of 3 GHz or less can be mapped to the first slot and the second slot, so that up to four ( 621) may be transmitted, and in a frequency band greater than 3 GHz and less than or equal to 6 GHz, the synchronization signal block may be mapped to the first, second, third, and fourth slots, so that a maximum of eight 622 may be transmitted. In case #2 (402) or case #3 (403) at a subcarrier interval of 30 kHz consisting of two slots in FIG. 4, a synchronization signal block in a frequency band of 3 GHz or less can be mapped starting with the first slot, so that up to 4 ( 631 and 641) may be transmitted, and in the frequency band above 3 GHz and below 6 GHz, the synchronization signal block may be mapped starting from the first and third slots, so that a maximum of eight (632, 642) may be transmitted.

Subcarrier spacing of 120 kHz and 240 kHz can be used at frequencies above 6 GHz. In the example of FIG. 6, in case #4 (510) at a subcarrier interval of 120 kHz consisting of two slots of FIG. 5, synchronization signal blocks 1, 3, 5, 7, 11, 13, 15, 17, 21, 23, 25, 27, 31, 33, 35, and 37 can be mapped starting from the slot, so that a maximum of 64 651 can be transmitted. In the example of FIG. 6, in case #5 (520) at a subcarrier interval of 240 kHz consisting of 4 slots of FIG. 5, the synchronization signal block is 1, 5, 9, 13, 21, 25, 29, 33 Since it can be mapped starting from the slot, a maximum of 64 (661) can be transmitted.

Meanwhile, the UE may acquire the SIB after decoding the PDCCH and the PDSCH based on the system information included in the received MIB. The SIB includes at least one of uplink cell bandwidth, random access parameters, paging parameters, parameters related to uplink power control, and the like.

Meanwhile, in 3GPP, a discussion on a reduced capability UE operating based on NR is ongoing. In the present disclosure, the low-complexity terminal acquires cell synchronization by receiving a synchronization signal block as in the embodiment of FIG. 4 or 5 in the initial cell connection for accessing a cell (or base station), and then acquires MIB or SIB Alternatively, it may be determined whether the cell supports a low-complexity terminal through a random access process. And when it is determined that the cell supports the low-complexity terminal, capability information about the bandwidth size supported by the low-complexity terminal in the cell, whether half-duplex communication is supported, and the number of transmission or reception antennas equipped (or supported), etc. By transmitting to the base station, the base station can know that the terminal attempting to access is a low-complexity terminal. Thereafter, the UE may proceed to the RRC connection mode for transmitting and receiving data with the cell by completing the random access process.

In general, the UE may form a radio link with the network through a random access procedure based on system information and synchronization with the network obtained in the cell search process of the cell. For random access, a contention-based or contention-free scheme may be used. When the UE performs cell selection and reselection in the initial access phase of the cell, for example, when moving from the RRC_IDLE (RRC idle) state to the RRC_CONNECTED (RRC connection) state, the contention-based random access method will be used can The contention-free random access may be used when downlink data arrives, in the case of handover, or in the case of reconfiguring uplink synchronization in the case of location measurement. Table 3 below exemplifies the conditions (events) under which the random access procedure is triggered in the 5G system. For a detailed description, refer to TS 38.300.

[Table 3]

7 is a diagram illustrating a random access procedure in a wireless communication system to which the present disclosure is applied. This shows a contention-based random access procedure.

Referring to FIG. 7 , although not shown, the base station transmits a synchronization signal block as described in the above embodiments. In this case, the base station may periodically transmit the synchronization signal block using beam sweeping. For example, a base station transmits a synchronization signal block including PSS/SSS (synchronization signal) and PBCH (broadcast channel) signals using up to 64 different beams for 5 ms, and a plurality of synchronization signal blocks transmit different beams. can be transmitted using The terminal detects (selects) a synchronization signal block having an optimal beam direction (eg, a beam direction in which the received signal strength is the strongest or is greater than a predetermined threshold), and PRACH (physical random access) related to the detected synchronization signal block channel) to transmit the preamble using the resource. That is, as a first step 701 of the random access procedure, the terminal transmits a random access preamble (or message 1) to the base station. Then, the base station measures a transmission delay value between the terminal and the base station, and performs uplink synchronization. Specifically, the UE transmits a random access preamble arbitrarily selected from within the random access preamble set given by system information in advance. In addition, the initial transmission power of the random access preamble is determined according to the pathloss between the base station and the terminal measured by the terminal. In addition, the UE may determine the transmission beam direction (or transmission beam or beam) of the random access preamble based on the synchronization signal block received from the base station and transmit the random access preamble by applying the determined transmission beam direction.

In a second step 702, the base station transmits a response (random access response, RAR, or message 2) to the detected random access attempt to the terminal. The base station transmits an uplink transmission timing control command to the terminal from the transmission delay value measured from the random access preamble received in the first step. In addition, the base station transmits an uplink resource and power control command to be used by the terminal as scheduling information. The scheduling information may include control information for an uplink transmission beam of the terminal. The RAR is transmitted through the PDSCH and may include at least one of the following information.

- Random access preamble sequence index detected by the network (or base station)

- TC-RNTI (temporary cell radio network temporary identifier)

- Uplink scheduling grant

- Timing advance value

If the terminal does not receive the RAR, which is scheduling information for message 3, from the base station for a predetermined time in the second step 702, the first step 701 is performed again. If the first step is performed again, the UE increases the transmission power of the random access preamble by a predetermined step and transmits it (this is referred to as power ramping), thereby increasing the random access preamble reception probability of the base station.

In the third step 703, the terminal has its own terminal identifier (which may be referred to as a UE contention resolution identity) to the base station (or if the terminal already has a valid terminal identifier (C-RNTI) in the cell before initiating the random access procedure) If there is, uplink information (scheduled transmission, or message 3) including uplink information (physical uplink shared channel, PUSCH) including the valid UE identifier, if present, using the uplink resource allocated in the second step 702 Transmission timing of the uplink data channel for transmitting message 3 follows the uplink transmission timing control command received from the base station in the second step 702. Also, the uplink data channel for transmitting message 3 The transmit power of n is determined in consideration of the power control command received from the base station and the power ramping value of the random access preamble in step 702. The uplink data channel for transmitting the message 3 is determined by the UE transmitting the random access preamble. Thereafter, it is the first uplink data signal transmitted by the terminal to the base station.

Finally, in the fourth step 704, when the base station determines that the terminal has performed random access without collision with other terminals, a message including the identifier of the terminal that has transmitted the uplink data in the third step 703 (resolving contention) A message (contention resolution message: CR message) or message 4 (message 4)) is transmitted to the corresponding terminal. In this regard, if a plurality of terminals receive the same TC-RNTI in the second step 702, the plurality of terminals that have received the same TC-RNTI receive message 3 in the third step 703, respectively. transmits to the base station including its own terminal identifier (UE contention resolution identity), and the base station transmits message 4 (CR message) including one terminal identifier among identifiers of a plurality of terminals for contention resolution. When the terminal receives message 4 (CR message) including its terminal identifier from the base station in the fourth step 704 (or message 3 including the terminal identifier (C-RNTI) in the third step 703) ) and, in the fourth step 704, when UE-specific control information including a CRC based on the UE identifier (C-RNTI) is received through the PDCCH), it is determined that the random access is successful. Therefore, among a plurality of terminals that have received the same TC-RNTI from the base station, a terminal that has confirmed that its own terminal identifier is included in message 4 (CR message) can confirm that the contention has been successful. In addition, the terminal transmits HARQ-ACK/NACK indicating whether the message 4 has been successfully received to the base station through a physical uplink control channel (PUCCH).

If the base station fails to receive the data signal from the terminal because the data transmitted by the terminal in the third step 703 collide with the data of the other terminal, the base station does not perform further data transmission to the terminal. Accordingly, if the terminal fails to receive the data transmitted from the base station in the fourth step 704 for a predetermined period of time, it is determined that the random access procedure has failed and starts again from the first step 701 .

As described above, in the first step 701 of the random access procedure, the UE may transmit the random access preamble on the PRACH. There are 64 available preamble sequences in each cell, and 4 long preamble formats and 9 short preamble formats can be used according to a transmission type. The UE generates 64 preamble sequences using a root sequence index and a cyclic shift value signaled as system information, and randomly selects one sequence and uses it as a preamble.

The base station transmits control information (or configuration information) indicating which time-frequency resources can be used for PRACH, at least one of SIB, higher layer signaling (RRC (Radio Resource Control) information), or DCI (Downlink Control Information). can be used to inform the terminal. The frequency resource for PRACH transmission indicates to the UE the start RB point of transmission, and the number of RBs used is determined according to the preamble format transmitted through the PRACH and the applied subcarrier interval. The time resource for PRACH transmission is a subframe index and start symbol including a preset PRACH configuration period, a PRACH transmission time (PRACH occasion, which may be mixed with a transmission time) as shown in Table 4 below, and a PRACH transmission time in the slot. The number, etc. may be informed through a PRACH configuration index (0 to 255). Through the PRACH configuration index, the random access configuration information included in the SIB, and the index of the SSB selected by the UE, the UE can check time and frequency resources for transmitting the random access preamble, and transmit the selected sequence as the preamble to the base station.

[Table 4]

In the LTE communication system, LTE-MTC (machine-type communication) technology has been developed to support application services such as the Internet of Things (IoT). LTE-MTC is an IoT-only access technology that considers key requirements such as low-power design, low-cost equipment supply, low construction cost, stable coverage, and large-scale terminal access implementation. In the LTE-MTC technology, a long battery life of the terminal can be guaranteed based on a low-power design by reducing the transmission speed and transmission bandwidth compared to the LTE service and introducing a power saving mode. In addition, since the transmission speed and transmission bandwidth are greatly reduced, the complexity of the communication modem is greatly reduced, so that it is possible to implement a low-cost terminal. In addition, in LTE-MTC, a single antenna technology can be applied instead of a multiple antenna (MIMO) technology, so power consumption can be minimized. In addition, since the existing LTE network can be used as it is, the existing LTE service and LTE-MTC service can be supported simultaneously without additional investment.

In addition, in order not to have any effect on the terminal supported by the existing LTE service, the base station includes additional information in the remaining bits of the MIB included in the PBCH for the existing LTE service so that the cell that transmitted the PBCH also supports the LTE-MTC service. and may indirectly indicate a resource location in which a system information block (system information block type 1-bandwidth reduced, SIB1-BR) for an additional LTE-MTC service is transmitted. Through this, the terminal or nodes supported by the LTE-MTC service can determine whether the cell found through the cell search is a cell supporting the LTE-MTC service or not, and if the cell also supports the LTE-MTC service, the corresponding system information block It is possible to obtain a location of a resource capable of receiving . In addition, a terminal supported by the existing LTE service may receive LTE service support without an additional operation or a new operation to the existing operation.

A terminal supporting the LTE-MTC service (hereinafter referred to as an MTC terminal) may perform a random access procedure based on the received various system information. Additionally, in the first step 701 of the random access procedure described in FIG. 7 , the MTC terminal transmits a random access preamble (hereinafter, PRACH (physical random access channel), PRACH preamble, and preamble can be mixed) to the base station before transmitting the CE level. (coverage enhancement level, CE-level) is determined. As in the description of the LTE-MTC service, in order to increase coverage, the MTC terminal may transmit the random access preamble repeatedly several times so that the terminals at the cell edge can also succeed in random access. However, since the UEs in the cell center do not need to repeatedly transmit the random access preamble, multiple CE levels are set and the number of repetitions of the random access preamble applied to each MTC UE, the time resource, the frequency resource, and the preamble Sequence resources may be configured differently.

Meanwhile, in order to reduce the complexity of a low-complexity terminal according to an embodiment of the present disclosure, a Half-Duplex Operation (or half-duplex) for operating without a duplexer in a Frequency Division Duplex (FDD) or Time Division Duplex (TDD) system communication) may be considered. Therefore, there is a need for a communication method for a low-complexity terminal to perform a half-duplex operation in an FDD or TDD system. In addition, the low-complexity terminal requires random access with a minimized delay time when performing a half-duplex operation.

According to the present disclosure, a method for a cell or a base station to recognize a low complexity (RedCap) terminal during an initial access process of a low complexity terminal (or half-duplex communication terminal) is proposed as follows. In the initial cell access for accessing a cell (or base station), the low-complexity terminal receives a synchronization block as described in the embodiments of FIG. 4 or 5 to obtain cell synchronization, and then obtains MIB or SIB or random access Through the procedure, it is determined whether the cell supports the low-complexity terminal, and when it is determined that the cell supports the low-complexity terminal, the bandwidth size supported by the low-complexity terminal in the cell, half-duplex operation support or full-duplex operation It is possible to inform the base station that the terminal attempting the access is a low-complexity terminal by transmitting capability information including at least one or more of support or not and the number of transmission or reception antennas provided (or supported) to the base station. Thereafter, the low-complexity terminal may proceed to the RRC connection mode for transmitting and receiving data with the cell by completing the random access procedure.

Next, a problem that may occur while the low-complexity terminal performs random access will be described with reference to FIG. 8 .

8 is a diagram illustrating a case in which a low-complexity terminal supporting half-duplex communication cannot transmit a random access preamble on a valid random access transmission occasion in a wireless communication system to which the present disclosure is applied. In the 5G system, FDD and TDD frame structures may refer to NR standards including TS 38.211.

Since the half-duplex communication terminal does not have a duplexer, a switching gap for changing the RF between transmission and reception is required when operating in the FDD 800 .

In FIG. 8 (a) is an RF switching gap 803 required for a half-duplex communication terminal between a synchronization signal block 801 and a valid random access transmission occasion 802 in the FDD 800 (shown as a thick box) is showing The half-duplex communication terminal may change the RF from reception to transmission during the RF switching gap 803 after receiving the synchronization signal block 801 . At this time, since all slots of the uplink (uplink) carrier of the FDD 800 are defined as valid random access transmission occasions, the half-duplex communication terminal performs RF switching (a time corresponding to the RF switching gap 803) During), random access transmission cannot be performed on a valid random access transmission occasion 804. As will be described in FIG. 9 , since valid random access transmission occasions are mapped with the index of the synchronization signal block 801 received by the half-duplex communication terminal, the half-duplex communication terminal overlaps with the RF switching interval valid random access transmission occasion ( 804), the random access transmission is delayed until a valid random access transmission occasion mapped with the index of the synchronization signal block appears again.

Meanwhile, in the TDD 810, there may be a period in which RF can be switched between a synchronization signal block and a valid random access occasion, such as N _gap . However, the interval may not be sufficient as a switching gap for changing the RF between transmission and reception of the half-duplex communication terminal.

(b) of FIG. 8 is an N _gap 814 that exists for an existing NR (5G) TDD terminal in order to space a distance between the synchronization signal block 811 and a valid random access transmission occasion 812 in the TDD 810 and The RF switching gap 813 (shown in bold box) required for a half-duplex communication terminal is shown. Control information (or configuration information) for the RF switching gap 813 required for the half-duplex communication terminal may be received by the terminal through at least one of SIB or higher layer signaling (RRC information) or DCI from the base station. , in the 3GPP standard, two frequency bands for use in the 5G system, FR1 (Frequency Range 1) (6 GHz or less) and FR2 (Frequency Range 2) (24 GHz or more), may be defined respectively. The half-duplex communication terminal changes the RF from reception to transmission during the RF switching gap 813 after receiving the synchronization signal block 811 . At this time, since the uplink (uplink) symbols after the Ngap 814 are defined as valid random access transmission occasions immediately after the transmission of the synchronization signal block 811 of the TDD 810 is finished, the half-duplex communication terminal transmits the RF Random access transmission cannot be performed on a valid random access transmission occasion (815) during switching (813). As will be described in FIG. 9 , valid random access transmission occasions overlap with the RF switching period 813 because the valid random access transmission occasions are mapped with the index of the synchronization signal block 811 received by the half-duplex communication terminal 815 ). When random access transmission is not performed in the TDD 810 , a problem in that random access transmission is delayed until a valid random access transmission occasion mapped with the index of the synchronization signal block appears again occurs in the TDD 810 . Hereinafter, the random access transmission occasion will be briefly referred to as a random access occasion.

Next, a mapping relationship between an index of a synchronization signal block and a valid random access occasion will be described with reference to FIG. 9 .

First, in the 5G system, the terminal receives the synchronization signal block, and from it, a control resource set (CORESET) #0 (which may correspond to a control resource set having a control resource set index or ID (Identity) of 0) and Search Space #0 (which may correspond to a search space index or a search space with ID 0) can be set. The UE may perform monitoring on the control resource set #0, assuming that the selected synchronization signal block and the DMRS (Demodulation Reference signal) transmitted from the control resource set #0 are QCL (Quasi Co Location). In addition, the terminal may receive system information based on the downlink control information transmitted from the control resource set #0. The UE may obtain PRACH-related configuration information for random access from the received system information. Upon obtaining the PRACH-related configuration information, the terminal may transmit a preamble to the base station in the PRACH based on the index of the received synchronization signal block when performing random access (that is, when the terminal receives the synchronization signal block having the index, the reception beam transmits the preamble in PRACH using a transmission beam having a QCL relationship with That is, the UE transmits the PRACH preamble for random access on the random access occasion mapped with the index of the received synchronization signal block.

9 is a diagram illustrating a relationship between a synchronization signal block and an effective random access occasion in a wireless communication system to which the present disclosure is applied.

In FIG. 9 , each SSB# i represents an index # i of each synchronization signal block described with reference to FIG. 4 or 5 . In FIG. 9, N denotes the number of synchronization signal blocks mapped to one random access occasion, and one time period (eg, at least one symbol period, at least one slot period, or at least one subframe period, etc.) It indicates that 4 random access occasions are multiplexed in frequency. As an example of a case where N is less than 1 (N<1, 901), it shows a case in which four random access occasions multiplexed in the frequency domain are mapped to one synchronization signal block. That is, one random access occasion is mapped to 1/4 synchronization signal block. Next, as an example of a case where N is 1 (N=1, 902), a case in which four random access occasions multiplexed in the frequency domain are mapped to four synchronization signal blocks is shown. That is, in this case, one random access occasion may be mapped to one synchronization signal block.

Next, as an example of a case where N is greater than 1 (N>1, 903), 4 frequency-multiplexed random access occasions are 8 synchronization signal blocks (SSB#1 to SSB#8) (SSB in FIG. 9 is SS ) and the mapped case are shown. That is, in this case, one random access occasion may be mapped to two synchronization signal blocks.

When explaining the problem that occurs when N is less than 1 (N<1, 901) or when N is 1 (N=1, 902), as shown in FIG. 8, the half-duplex communication terminal performs synchronization signal block 1 ( SSB#1) is received, but when random access transmission cannot be performed on the first valid random access occasion of FIG. 9 due to RF switching, the half-duplex communication terminal is mapped to the synchronization signal block 1 (SSB#1) There is a problem in that random access transmission cannot be performed until the next random access occasion appears.

In order to solve the above problems, the present disclosure proposes the following embodiments.

First, in the present disclosure, the base station configures a separate random access resource for each of a low-complexity terminal or a low-complexity terminal supporting full-duplex and a low-complexity terminal supporting half-duplex, and the The configuration information on the random access resource is transmitted to the low-complexity terminal through the system information, and the low-complexity terminal that has received the system information is each of the following first and second embodiments of the random access resource, as well as a combination thereof. can be applied. As is well known, the full-duplex communication refers to a communication method in which transmission and reception can be performed simultaneously, and the half-duplex communication refers to a communication method in which transmission and reception can be performed, but cannot be simultaneously performed. In half-duplex communication, it is necessary to switch between the transmit operation and the receive operation.

The system information for transmitting information on the random access resource may be system information transmitted separately from system information for a terminal supporting a different version of a standard within a cell, and the base station supports a different version of the standard. By setting separate random access resources for the terminal and the low-complexity terminal, it may be possible to distinguish whether the terminal supporting the different version of the standard performs random access or the low-complexity terminal performs random access. In addition, in a wireless communication system using FDD and TDD as a hybrid, it is possible to combine and implement the following first and second embodiments.

First, in the first embodiment, when the terminal reports the low-complexity-related terminal capability to the base station and the low-complexity terminal communicates with the base station in half-duplex operation, in the case of the conventional NR TDD described in FIG. 8, the terminal In addition to the N _gap existing for this purpose, the RF switching gap required for half-duplex communication of the low-complexity terminal is ensured, and random access transmission delay is performed on a valid random access occasion mapped with the index of the synchronization signal block received by the low-complexity terminal. suggested a way to solve it. In this embodiment, the low-complexity terminal may determine that the random access occasion within the RF switching gap (or overlapping the RF switching gap and the time domain) is not valid. In this case, the low-complexity terminal excludes an invalid random access occasion that overlaps with the RF switching gap in the time domain, and then determines the preamble transmission in random access based on the next valid random access occasion and the index and mapping of the synchronization signal block. Therefore, the random access transmission delay described with reference to FIGS. 8 and 9 can be solved.

Meanwhile, as in the example of FIG. 10B , an RF switching gap 1023 required for half-duplex communication of the low-complexity terminal may be included within the N _gap 814 period. In this case, the low complexity terminal may determine that the random access occasion within the N _gap interval (or overlapping the N _gap interval and the time domain) is not valid. Alternatively, it may be determined that the random access occasion in the random access slot is valid when the following [condition] is satisfied.

- [Condition]: The random access occasion does not exist in front of the synchronization signal block in the random access slot, and the random access occasion 1022 is a symbol of at least N _gap 814 from the last symbol in which the synchronization signal block 811 is transmitted. Start after(s). Alternatively, the random access occasion 1022 may be started with a predetermined offset after the symbol(s) of the N _gap 814 interval.

Next, the N _gap may be defined as follows.

For example, in the case of the B4 format PRACH (random access) preamble in standard TS38.211 Table 6.3.3.1-2, N _gap is 0 symbol, and in the standard TS38.211 Table 6.3.3.1-1, SCS (Subcarrier spacing) of the PRACH preamble ) is 1.25 kHz or 5 kHz, N _gap is 0 symbol. In Table 6.3.3.1-2 of standard TS38.211, when the SCS of the PRACH preamble is 15 kHz, 30 kHz, 60 kHz, or 120 kHz, N _gap is 2 symbols. That is, in the case of the PRACH preamble in the standard TS38.211 table 6.3.3.1-1 used only for FR1, N _gap is 0 symbol, and in the standard TS38.211 table 6.3.3.1-2, when the SCS is 15 kHz or 30 kHz, FR1 In the case of the PRACH preamble used for PRACH or SCS used for FR2 at 60 kHz or 120 kHz, N _gap is 2 symbols.

The first embodiment is applied when the low-complexity terminal supporting the half-duplex communication determines that the carrier or cell receiving the synchronization signal block is TDD or unpaired spectrum, or when a specific carrier or cell is TDD or unpaired spectrum from system information can do. In the NR standard, TDD is also called unpaired spectrum as described in TS 38.213. Alternatively, in the first embodiment, when the low-complexity terminal supporting half-duplex communication determines that the carrier or cell receiving the synchronization signal block is FDD or paired spectrum, or when a specific carrier or cell receives FDD or paired spectrum from system information It is possible to apply to determine whether a random access occasion is valid for an uplink frequency.

On the other hand, in the case of a low-complexity terminal supporting full-duplex communication, it can be determined that all random access occasions are valid every hour on an uplink frequency of the FDD cell.

Next, in the second embodiment, when the terminal reports to the base station the terminal capability related to the low complexity to the base station, and the low complexity terminal performs communication with the base station in half-duplex operation, in the case of the conventional NR FDD described in FIG. A method for securing an RF switching gap required for half-duplex communication of a low-complexity terminal and solving a random access transmission delay on an effective random access occasion mapped with an index of a synchronization signal block received by the low-complexity terminal is proposed. . In this embodiment, the low-complexity terminal may determine that the random access occasion within the RF switching gap (or overlapping the RF switching gap and the time domain) is not valid. Therefore, the low-complexity terminal excludes an invalid random access occasion that temporally overlaps with the RF switching gap and determines the random access performance based on the next valid random access occasion and the index and mapping of the synchronization signal block, The random access transmission delay described with reference to FIG. 8 and FIG. 9 can be solved. Embodiment 2 can be applied when the low-complexity terminal determines that the carrier or cell receiving the synchronization signal block is FDD or paired spectrum, or when a specific carrier or cell receives FDD or paired spectrum from system information.

11 is a diagram illustrating a method for a low-complexity terminal to perform a random access procedure in a wireless communication system according to an embodiment of the present disclosure. The method of FIG. 11 may be applied to the above-described first and second embodiments.

In step 1101, the low-complexity terminal receives configuration information including resource information for random access from the low-complexity terminal from the base station. The configuration information may be provided to the UE through SIB or RRC information or DCI. In step 1103, the low-complexity terminal transmits capability information of the low-complexity terminal including whether half-duplex communication is supported to the base station. In this embodiment, it is assumed that the low-complexity terminal supports half-duplex communication. When the low-complexity terminal performs random access in step 1105, it checks whether there is a random access transmission occasion overlapping the RF switching gap in the time domain. And in step 1107, when there is a random access transmission occasion overlapping with the RF switching gap, the low complexity terminal excludes the overlapping random access transmission occasion on the basis of the received resource information for random access with the base station on the next random access transmission occasion A random access procedure is performed. If the resource information for the random access is configured in advance so that the RF switching gap and the random access transmission occasion do not overlap, step 1105 may be omitted, and the UE may directly perform the random access procedure based on the resource information. .

10A and 10B are diagrams illustrating an example of a random access resource allocation method for a low-complexity terminal according to an embodiment of the present disclosure.

(a) of FIG. 10a shows the index of the synchronization signal block except for the random access occasion 804 overlapping with the RF switching gap 803 in the time domain in the second embodiment for NR FDD and then mapped with the valid random access An example of a resource allocation method for performing random access on occasion 1002 is shown. 10a (b) shows the index of the synchronization signal block except for the random access occasion 815 that overlaps the RF switching gap 813 in the time domain in the first embodiment for NR TDD, and then maps valid random access An example of a resource allocation method for performing random access on occasion 1012 is shown. 10B shows at least an N _gap 814 interval from the last symbol in which the synchronization signal block 811 is transmitted when the RF switching gap 1023 is included in the N _gap 814 interval in the first embodiment for NR TDD. An example of a resource allocation method for performing random access on a random access occasion 1022 after symbol(s) of is illustrated.

As described in the example of FIG. 8, reference numbers 804 and 815 are random access occasions overlapping the RF switching intervals 803 and 813, and in the example of FIG. In step 1101, it may be allocated (set) based on resource information for random access. For example, the resource of the next valid random access occasion (1002) is a predetermined time interval (eg, at least one symbol interval or at least one slot interval or at least one from the first symbol after the overlapping random access occasion (804, 815)) may be allocated (set) during the subframe period of . In another embodiment, it is also possible to allocate (set) the resources of the next valid random access occasions 1002 and 1012 with a predetermined offset after the overlapping random access occasions 804 and 815.

12 is a diagram illustrating a method for a base station to perform a random access procedure for a low complexity terminal in a wireless communication system according to an embodiment of the present disclosure. The method of FIG. 11 may be applied to the above-described first and second embodiments.

In step 1201 of FIG. 12 , the base station transmits configuration information including resource information for random access in the low-complexity terminal. In step 1203, the base station receives capability information of the low-complexity terminal including whether to support half-duplex communication from the low-complexity terminal. And in step 1205, when there is a random access occasion overlapping the RF switching gap, the base station excludes the overlapping random access transmission occasion based on the transmitted resource information for the random access and performs a random access procedure with the terminal on the next random access transmission occasion. carry out

Next, the third embodiment is an embodiment in which the base station sets a common random access resource for all terminals in a cell without setting a separate random access resource for the low complexity terminal. In this case, the configuration information for the random access resource may be transmitted to all terminals in the cell through system information, and the terminal receiving the system information may perform the following operation on the random access resource.

In the third embodiment, when the base station determines that a low-complexity terminal exists in a corresponding cell and that the low-complexity terminal can communicate with the base station in half-duplex operation according to the capability information received from the terminal, in the cell In the case of the conventional NR TDD described in the example of FIG. 8 , all terminals may apply an N _{gap_cell} similar to the N _gap 814 existing for the terminal to all terminals in the cell. However, the N _{gap_cell} may be a value including the RF switching gap required for half-duplex communication of the low-complexity terminal in addition to the N _gap existing for the terminal in the case of the existing NR TDD. Alternatively, the N _{gap_cell} may have the same value as N _gap . Therefore, the N _{gap_cell} may be signaled to all terminals in the cell as system information, and all terminals in the cell receiving the system information are in the N _{gap_cell} (or overlapping with the N _{gap_cell} in the time domain) random access occasion may be judged to be invalid. Therefore, the low-complexity terminal excludes an invalid random access occasion overlapping the N _{gap_cell} in the time domain, and as in the above-described embodiments, random access based on the next valid random access occasion and the index and mapping of the synchronization signal block transmission can be determined. Therefore, according to the above-described embodiments of the present disclosure, the random access transmission delay described in the examples of FIGS. 8 and 9 can be solved. Since the third embodiment is commonly applied to all terminals in a cell, there may be an advantage in not requiring a separate random access transmission resource only for low-complexity terminals.

13 is a block diagram illustrating the configuration of a low-complexity terminal or a general terminal performing an operation according to an embodiment of the present disclosure.

Referring to FIG. 13 , a terminal 1300 may include a transceiver 1310 , a processor 1320 , and a memory 1030 . In a wireless communication system to which the present disclosure is applied as described above with reference to FIGS. 1 to 9 , the terminal 1300 according to the present disclosure may operate according to the methods described in the embodiments of FIGS. 10A and 10B to 12 . However, the components of the terminal 1300 according to an embodiment are not limited to the above-described example. According to another embodiment, the terminal 1300 may include more components than the above-described components, or may include fewer components in the case of a low-complexity terminal. In addition, in a specific case, the transceiver 1310 , the processor 1320 , and the memory 1030 may be implemented in the form of a single chip.

The transceiver 1310 may include a transmitter and a receiver according to another embodiment. The transceiver 1310 may transmit/receive a signal to/from the base station. The signal may include control information and data. To this end, the transceiver 1310 may include an RF transmitter that up-converts and amplifies a frequency of a transmitted signal, and an RF receiver that low-noise amplifies and down-converts a received signal. In addition, the transceiver 1310 may receive a signal through a wireless channel, output it to the processor 1320 , and transmit the signal output from the processor 1320 through a wireless channel.

The processor 1320 may control a series of processes in which the terminal 1300 may operate according to the above-described embodiment of the present disclosure. For example, the processor 1320 may include a random access preamble transmission method according to an embodiment of the present disclosure, that is, a resource and transmission setting method for transmitting a random access preamble corresponding to a low-complexity service, a random access preamble transmission resource of a corresponding terminal, and A method of determining a setting and the like can be controlled differently.

The memory 1330 may store control information or data such as random access preamble transmission resource setting included in a signal obtained from the terminal 1300 , and data required for control of the processor 1320 and data required for control by the processor 1320 . It may have an area for storing generated data and the like.

14 is a block diagram illustrating a configuration of a base station performing an operation according to an embodiment of the present disclosure.

Referring to FIG. 14 , a base station 1400 may include a transceiver 1410 , a processor 1420 , and a memory 1430 . As described in FIGS. 1 to 9 , in a wireless communication system to which the present disclosure is applied, the base station 1400 according to the present disclosure may operate according to the methods described in the embodiments of FIGS. 10A and 10B to 12 . However, the components of the base station 1400 according to an embodiment are not limited to the above-described example. According to another embodiment, the base station 1400 may include more or fewer components than the above-described components. In addition, in a specific case, the transceiver 1410 , the processor 1420 , and the memory 1430 may be implemented in the form of a single chip. The transceiver 1410 may include a transmitter and a receiver according to another embodiment. The transceiver 1410 may transmit/receive a signal to/from the terminal. The signal may include control information and data. To this end, the transceiver 1410 may include an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and down-converts a received signal. Also, the transceiver 1410 may receive a signal through a wireless channel, output it to the processor 1420 , and transmit the signal output from the processor 1420 through a wireless channel.

The processor 1420 may control a series of processes so that the base station 1400 can operate according to the above-described embodiment of the present disclosure. For example, the processor 1420 may include a random access preamble transmission method according to an embodiment of the present disclosure, that is, a resource and transmission setting method for transmitting a random access preamble corresponding to a low-complexity service, a random access preamble transmission resource of a corresponding terminal, and A method of determining a setting and the like can be controlled differently.

The memory 1430 may store control information such as random access preamble transmission resource setting determined by the base station 1400, data, or control information and data received from the terminal, and data necessary for controlling the processor 1420 and the processor 1420 ) may have an area for storing data generated during control.

On the other hand, the embodiments of the present disclosure disclosed in the present specification and drawings are only presented as specific examples to easily explain the technical content of the present disclosure and help the understanding of the present disclosure, and are not intended to limit the scope of the present disclosure. That is, it is apparent to those of ordinary skill in the art to which other modifications are possible based on the technical spirit of the present disclosure. In addition, each of the above embodiments may be operated in combination with each other as needed.

Claims (20)

A method for a low-complexity terminal to perform a random access procedure in a wireless communication system, the method comprising:
Receiving configuration information including resource information for random access in the low-complexity terminal from a base station;
transmitting capability information of the low-complexity terminal including whether half-duplex communication is supported to the base station;
When performing the random access, the process of checking whether there is a random access opportunity (occasion) overlaps with a radio frequency (RF) switching gap in the time domain; and
When there is the random access opportunity overlapping the RF switching gap, based on the received resource information for random access, performing the random access procedure with the base station at the next random access opportunity excluding the overlapping random access transmission opportunity A method for a low-complexity terminal to perform a random access procedure, comprising the steps of:
The method of claim 1,
The process of performing the random access procedure is,
and transmitting a message including a preamble for the random access using the resource of the next random access opportunity set based on the resource information.
The method of claim 1,
The next random access opportunity is a method in which the low-complexity terminal performs a random access procedure mapped to the index of the synchronization signal block received by the low-complexity terminal.
The method of claim 1,
A method for performing a random access procedure in which the low-complexity terminal and the base station communicate using at least one of a frequency division duplex (FDD) scheme and a time division duplex (TDD) scheme.
The method of claim 1,
The method of performing a random access procedure by a low-complexity terminal in which the next random access opportunity is set for a predetermined time period with an offset or from a first symbol after the overlapping random access opportunity.
In a low-complexity terminal in a wireless communication system,
transceiver; and
Receive configuration information including resource information for random access in the low-complexity terminal from the base station through the transceiver,
Transmitting capability information of the low-complexity terminal including whether half-duplex communication is supported to the base station through the transceiver,
When performing the random access, check whether there is a random access opportunity (occasion) overlapping the RF (radio frequency) switching gap in the time domain,
When there is the random access opportunity overlapping the RF switching gap, based on the received resource information for random access, the base station and the random access at the next random access opportunity excluding the overlapping random access transmission opportunity through the transceiver A low-complexity terminal comprising a processor for performing the procedure.
7. The method of claim 6,
The processor is
A low-complexity terminal for transmitting a message including a preamble for the random access through the transceiver using the resource of the next random access opportunity set based on the resource information.
7. The method of claim 6,
The next random access opportunity is a low-complexity terminal mapped with an index of a synchronization signal block received by the low-complexity terminal.
7. The method of claim 6,
The low complexity terminal and the base station communicate using at least one of a frequency division duplex (FDD) scheme and a time division duplex (TDD) scheme.
7. The method of claim 6,
The next random access opportunity is a low complexity terminal that is set for a predetermined time period from the first symbol after the overlapping random access opportunity or with an offset.
A method for a base station to perform a random access procedure in a wireless communication system, the method comprising:
Transmitting configuration information including resource information for random access in a low-complexity terminal;
receiving, from the low-complexity terminal, capability information of the low-complexity terminal including whether half-duplex communication is supported; and
When there is a random access opportunity overlapping with a radio frequency (RF) switching gap, based on the transmitted resource information for random access, the low complexity terminal and the next random access opportunity excluding the overlapping random access opportunity A method for a base station to perform a random access procedure, comprising the step of performing a random access procedure.
12. The method of claim 11,
The process of performing the random access procedure is,
and receiving a message including a preamble for the random access by using the resource of the next random access opportunity set based on the resource information.
12. The method of claim 11,
The next random access opportunity is a method in which a base station mapped with an index of a synchronization signal block received by the low-complexity terminal performs a random access procedure.
12. The method of claim 11,
A method of performing a random access procedure in which the low-complexity terminal and the base station communicate using at least one of a frequency division duplex (FDD) scheme and a time division duplex (TDD) scheme.
12. The method of claim 11,
The method for the base station to perform a random access procedure in which the next random access opportunity is set for a predetermined time period with an offset or from the first symbol after the overlapping random access opportunity.
In a base station in a wireless communication system,
transceiver; and
Transmitting configuration information including resource information for random access in a low-complexity terminal through the transceiver,
Receives capability information of the low-complexity terminal including whether half-duplex communication is supported from the low-complexity terminal through the transceiver,
If there is a random access opportunity overlapping with a radio frequency (RF) switching gap through the transceiver, based on the transmitted resource information for random access, the next random access opportunity excluding the overlapping random access opportunity A base station comprising a complexity terminal and a processor for performing the random access procedure.
17. The method of claim 16,
The processor is
A base station for receiving a message including a preamble for the random access through the transceiver using the resource of the next random access opportunity set based on the resource information.
17. The method of claim 16,
The next random access opportunity is the base station mapped to the index of the synchronization signal block received by the low-complexity terminal.
17. The method of claim 16,
The low-complexity terminal and the base station communicate using at least one of a frequency division duplex (FDD) scheme and a time division duplex (TDD) scheme.
17. The method of claim 16,
The next random access opportunity is set from the first symbol after the overlapping random access opportunity or for a predetermined time interval with an offset.

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