KR102552288B1 - Method and apparatus for transmitting and receiving data in wireless communication system - Google Patents

Abstract

The present disclosure relates to a method and apparatus for transmitting and receiving data in a wireless communication system, and a method for transmitting and receiving data in a wireless communication system according to an embodiment includes at least one SSB among Synchronization Signal Blocks (SSBs) received by a terminal from a base station. Selecting, by the terminal, transmitting a random access preamble on a Physical Random Access CHannel (PRACH) occasion determined based on the selected SSB, and by the terminal, receiving a random access response to the random access preamble from the base station includes

Description

Method and apparatus for transmitting and receiving data in a wireless communication system { METHOD AND APPARATUS FOR TRANSMITTING AND RECEIVING DATA IN WIRELESS COMMUNICATION SYSTEM}

The present disclosure relates to a wireless communication system, and relates to a method and apparatus for smoothly providing a service in a wireless communication system. More specifically, it relates to a method and apparatus for transmitting and receiving data in a wireless communication system.

Efforts are being made to develop an improved 5G communication system or pre-5G communication system to meet the growing demand for wireless data traffic after the commercialization of the 4G communication system. For this reason, the 5G communication system or pre-5G communication system is being called a system after a 4G network (Beyond 4G Network) communication system or an LTE system (Post LTE). 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 mmWave band (eg, a 60 gigabyte (60 GHz) band). In order to mitigate the path loss of radio waves and increase the propagation distance of radio waves in the ultra-high frequency band, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) are used in 5G communication systems. ), array antenna, analog beam-forming, and large scale antenna technologies have been discussed and applied to NR systems. In addition, to improve the network of the system, in the 5G communication system, an evolved small cell, an advanced small cell, a cloud radio access network (cloud RAN), and an ultra-dense network , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation etc. are being developed. In addition, in the 5G system, advanced coding modulation (Advanced Coding Modulation: ACM) methods FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), advanced access technologies FBMC (Filter Bank Multi Carrier), NOMA (non-orthogonal multiple access), SCMA (sparse code multiple access), and the like are being developed.

On the other hand, the Internet is evolving from a human-centered connection network in which humans create and consume information to an Internet of Things (IoT) network in which information is exchanged and processed between distributed components such as objects. IoE (Internet of Everything) technology, which combines IoT technology with big data processing technology through connection with a cloud server, etc., is also emerging. In order to implement IoT, technical elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology are required, and recently, sensor networks for connection between objects and machine to machine , M2M), and MTC (Machine Type Communication) technologies are being studied. In the IoT environment, intelligent IT (Internet Technology) services that create new values in human life by collecting and analyzing data generated from connected objects 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 appliances, 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 (M2M), and machine type communication (MTC) is implemented by techniques such as beamforming, MIMO, and array antenna. The application of the 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.

As various services can be provided according to the above and the development of mobile communication systems, a method for effectively providing these services is required.

The disclosed embodiments provide an apparatus and method capable of effectively providing services in a mobile communication system.

A method for transmitting and receiving data in a wireless communication system according to an embodiment includes the steps of selecting at least one SSB among Synchronization Signal Blocks (SSBs) received from a base station by a terminal, a PRACH determined by the terminal based on the selected SSB ( Transmitting a random access preamble on a Physical Random Access CHannel) occasion and receiving, by a terminal, a random access response to the random access preamble from a base station.

1 is a diagram illustrating the structure of an LTE system according to an embodiment.
2 is a diagram illustrating a radio protocol structure in an LTE system to which an embodiment is applied.
3 is a diagram showing the structure of a next-generation mobile communication system to which an embodiment is applied.
4 is a diagram showing a radio protocol structure of a next-generation mobile communication system to which an embodiment is applied.
5 is a diagram illustrating downlink and uplink channel frame structures of a next-generation mobile communication system to which an embodiment is applied.
6 is a diagram for explaining a procedure for repeatedly transmitting Msg3 (Message 3) when a terminal performs random access to a base station in a next-generation mobile communication system to which an embodiment is applied.
7 is a diagram for explaining a procedure for transmitting Msg3 when a terminal performs random access to a base station in a next-generation mobile communication system to which an embodiment is applied.
8 is a block diagram illustrating the structure of a terminal according to an embodiment.
9 is a block diagram showing the structure of a base station according to an embodiment.
10 is a diagram for explaining a procedure for a terminal to transmit capability information to a network according to an embodiment.
11 is a diagram for explaining a procedure for a terminal to transmit capability information to a network according to an embodiment.
12 is a diagram for explaining a procedure for a terminal to transmit capability information to a network according to an embodiment.
13 is a block diagram illustrating the structure of a terminal according to an embodiment.
14 is a block diagram showing the structure of a base station according to an embodiment.

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 it by omitting unnecessary description.

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

Advantages and features of the present disclosure, and methods of achieving them, will become clear 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 disclosed below and may be implemented in various different forms, only the present embodiments make the disclosure of the present disclosure complete, and common knowledge in the art to which the present disclosure belongs. It is provided to completely inform the person who has the scope of the invention, and the present disclosure is only defined by the scope of the claims. Like reference numbers designate like elements throughout the specification.

At this time, it will be understood that each block of the process flow chart diagrams and combinations of the flow chart diagrams can be performed 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, so that the instructions executed by the processor of the computer or other programmable data processing equipment are described in the flowchart block(s). It may result in creating means to perform functions. These computer program instructions may also be stored in a computer usable or computer readable memory that can be directed to a computer or other programmable data processing equipment to implement functionality in a particular way, such that the computer usable or computer readable memory The instructions stored in are also capable of producing an article of manufacture containing instruction means that perform the functions described in the flowchart block(s). The computer program instructions can also be loaded on a computer or other programmable data processing equipment, so that a series of operational steps are performed on the computer or other programmable data processing equipment to create a computer-executed process to generate computer or other programmable data processing equipment. Instructions for performing processing equipment may also 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 specified logical function(s). It should also be noted that in some alternative implementations it is possible for the functions mentioned in the blocks to occur out of order. For example, it is possible that two blocks shown in succession may in fact be performed substantially concurrently, or that the blocks may sometimes be performed in reverse order depending on their 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' performs certain roles. do. However, '~ part' is not limited to software or hardware. '~bu' may be configured to be in an addressable storage medium and may be configured to reproduce one or more processors. Therefore, as an example, '~unit' refers to components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, and procedures. , subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Functions provided within components and '~units' may be combined into smaller numbers 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 a secure multimedia card. Also, in the embodiment, '~ unit' may include one or more processors.

In the present disclosure, downlink (DL) is a radio transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) refers to a radio transmission path of a signal transmitted from a terminal to a base station. In addition, although an LTE or LTE-A system may be described as an example in the following, embodiments of the present disclosure may be applied to other communication systems having a similar technical background or channel type. For example, the 5th generation mobile communication technology (5G, new radio, NR) developed after LTE-A can be included in a system to which an embodiment of the present disclosure can be applied. It may also be a concept that includes other similar services. In addition, the present disclosure can be applied to other communication systems through some modifications within a range that does not greatly deviate from the scope of the present disclosure as determined by those skilled in the art.

A term used in the following description to identify a connection node, a term referring to network entities, a term referring to messages, a term referring to an interface between network entities, and a term referring to various types of identification information. Etc. are illustrated for convenience of description. Accordingly, the present disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

For convenience of description below, the present disclosure uses terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standard. However, the present disclosure is not limited by terms and names, and may be equally applied to systems conforming to other standards.

Hereinafter, a base station is a subject that performs resource allocation of a terminal, and may be at least one of a gNode B, an eNode B, a Node B, a base station (BS), a wireless access unit, a base station controller, or a node on a network. The terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, or a multimedia system capable of performing communication functions. Of course, it is not limited to the above examples.

In particular, the present disclosure can be applied to 3GPP NR (5th generation mobile communication standard). In addition, the present disclosure provides intelligent services based on 5G communication technology and IoT related technology (eg, smart home, smart building, smart city, smart car or connected car, health care, digital education, retail, security and safety related service, etc.). In the present disclosure, eNB may be used interchangeably with gNB for convenience of description. That is, a base station described as an eNB may indicate a gNB. In addition, the term terminal may refer to mobile phones, NB-IoT devices, sensors, as well as other wireless communication devices.

The wireless communication system has moved away from providing voice-oriented services in the early days and, 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's High Rate Packet Data (HRPD), UMB (Ultra Mobile Broadband), and IEEE's 802.16e, a broadband wireless network that provides high-speed, high-quality packet data services. evolving into a communication system.

As a representative example of a broadband wireless communication system, in an LTE system, an Orthogonal Frequency Division Multiplexing (OFDM) method is employed in downlink (DL), and Single Carrier Frequency Division Multiplexing (SC-FDMA) in uplink (UL). ) method is used. Uplink refers to a radio link in which a terminal (UE; User Equipment or MS; Mobile Station) transmits data or control signals to a base station (eNode B or BS; Base Station), and downlink refers to a radio link in which a base station transmits data or control signals to a terminal. A radio link that transmits signals. The multiple access method as described above distinguishes data or control information of each user by allocating and operating time-frequency resources to carry data or control information for each user so that they do not overlap each other, that is, so that orthogonality is established. do.

As a future communication system after LTE, that is, a 5G communication system, since it should be able to freely reflect various requirements such as users and service providers, a service that satisfies various requirements at the same time must be supported. 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

According to an embodiment, eMBB may aim to provide a data transmission rate that is more improved than that supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, an eMBB must be able to provide a peak data rate of 20 Gbps in downlink and a peak data rate of 10 Gbps in uplink from the perspective of one base station. In addition, the 5G communication system may need to provide a user perceived data rate while providing a maximum transmission rate. In order to satisfy these requirements, the 5G communication system may require improvement of various transmission and reception technologies, including a more advanced multi-input multi-output (MIMO) transmission technology. In addition, while signals are transmitted using a maximum 20MHz transmission bandwidth in the 2GHz band currently used by LTE, the 5G communication system uses a frequency bandwidth wider than 20MHz in a frequency band of 3 to 6GHz or 6GHz or higher to meet the requirements of the 5G communication system. data transfer rate can be satisfied.

At the same time, mMTC is being considered to support application services such as Internet of Things (IoT) in 5G communication systems. In order to efficiently provide the Internet of Things using mMTC, it may be required to support access of large-scale terminals within a cell, improve coverage of terminals, improve battery time, and reduce terminal costs. Since IoT 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/km2) in a cell. In addition, due to the nature of the service, terminals supporting mMTC are likely to be located in shadow areas that are not covered by cells, such as the basement of a building, so a wider coverage than other services provided by the 5G communication system may be required. A terminal supporting mMTC must be composed of a low-cost terminal, and since it is difficult to frequently replace a battery of the terminal, a very long battery life time such as 10 to 15 years may be required.

Finally, in the case of URLLC, as a cellular-based wireless communication service used for a specific purpose (mission-critical), remote control for robots or machinery, industrial automation, It can be used for services used in unmanned aerial vehicles, remote health care, and emergency alerts. Therefore, communications provided by URLLC may need to provide very low latency (ultra-low latency) and very high reliability (ultra-reliability). For example, a service supporting URLLC must satisfy an air interface latency of less than 0.5 milliseconds, and at the same time may have a requirement of a packet error rate of 10-5 or less. Therefore, for the service supporting URLLC, the 5G system must provide a transmit time interval (TTI) that is smaller than that of other services, and at the same time, design that allocates wide resources in the frequency band to secure the reliability of the communication link. items may be requested.

The three services considered in the aforementioned 5G communication system, that is, eMBB, URLLC, and mMTC, can be multiplexed and transmitted in one system. At this time, different transmission/reception techniques and transmission/reception parameters may be used between services in order to satisfy different requirements of each service. However, the above-mentioned mMTC, URLLC, and eMBB are only examples of different service types, and the service types to which the present disclosure is applied are not limited to the above-mentioned examples.

In addition, although the embodiments of the present disclosure are described below using LTE, LTE-A, LTE Pro, or 5G (or NR, next-generation mobile communication) systems as examples, other communication systems having a similar technical background or channel type are also subject to the present disclosure. An embodiment of may be applied. In addition, the embodiments of the present disclosure can be applied to other communication systems through some modification within a range that does not greatly deviate from the scope of the present disclosure as judged by a skilled person with technical knowledge.

In the following description of the present disclosure, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present disclosure, the detailed description will be omitted. Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings.

1 is a diagram illustrating the structure of an LTE system according to an embodiment.

Referring to FIG. 1, the radio access network of the LTE system includes a next-generation base station (Evolved Node B, hereinafter ENB, Node B or base station) (1a-05, 1a-10, 1a-15, 1a-20), a mobility management entity ( It can be composed of Mobility Management Entity (MME) (1a-25) and S-GW (1a-30, Serving-Gateway). A user equipment (UE or terminal) 1a-35 may access an external network through ENBs 1a-05 to 1a-20 and S-GW 1a-30.

In FIG. 1A, ENBs 1a-05 to 1a-20 may correspond to existing Node Bs of a Universal Mobile Telecommunication System (UMTS) system. The ENB may be connected to the UE 1a-35 through a radio channel and may perform a more complex role than the existing Node B. In the LTE system, all user traffic including real-time services such as VoIP (Voice over IP) through Internet protocol can be serviced through a shared channel. Therefore, a device for performing scheduling by collecting status information such as buffer status, available transmission power status, and channel status of UEs is required, and ENBs 1a-0 to 1a-20 can take charge of this. One ENB can typically control multiple cells. For example, in order to implement a transmission rate of 100 Mbps, an LTE system may use Orthogonal Frequency Division Multiplexing (OFDM) as a radio access technology in a 20 MHz bandwidth, for example. In addition, an Adaptive Modulation & Coding (AMC) method for determining a modulation scheme and a channel coding rate according to the channel condition of the terminal may be applied. The S-GW 1a-30 is a device that provides a data bearer, and can create or delete a data bearer under the control of the MME 1a-25. The MME 1a-25 is a device in charge of various control functions as well as a mobility management function for a terminal, and may be connected to a plurality of base stations.

2 is a diagram illustrating a radio protocol structure in an LTE system to which an embodiment is applied. Referring to FIG. 2, the radio protocols of the LTE system are Packet Data Convergence Protocol (PDCP) (1b-05, 1b-40), Radio Link Control (RLC) (Radio Link Control, RLC) ( 1b-10, 1b-35), and Medium Access Control (MAC) (1b-15, 1b-30). PDCP may be in charge of operations such as IP header compression/restoration. The main functions of PDCP can be summarized as follows.

- Header compression and decompression (ROHC only)

- Transfer of user data

- In-sequence delivery of upper layer PDUs at PDCP re-establishment procedure for RLC AM (Acknowledged Mode)

- Order reordering function (For split bearers in DC (only support for RLC AM): PDCP PDU routing for transmission and PDCP PDU reordering for reception)

- Duplicate detection of lower layer SDUs at PDCP re-establishment procedure for RLC AM

- Retransmission of PDCP SDUs at handover and, for split bearers in DC, of PDCP PDUs at PDCP data-recovery procedure, for RLC AM)

- Ciphering and deciphering

- Timer-based SDU discard in uplink.

The Radio Link Control (RLC) 1b-10, 1b-35 may reconfigure the PDCP Packet Data Unit (PDU) into an appropriate size and perform an Automatic Repeat Request (ARQ) operation. . The main functions of RLC can be summarized as follows.

- Transfer of upper layer PDUs

- ARQ function (Error Correction through ARQ (only for AM data transfer))

- Concatenation, segmentation and reassembly of RLC SDUs (only for UM and AM data transfer)

- Re-segmentation of RLC data PDUs (only for AM data transfer)

- Reordering of RLC data PDUs (only for UM and AM data transfer)

- Duplicate detection (only for UM and AM data transfer)

- Error detection function (Protocol error detection (only for AM data transfer))

- RLC SDU discard function (RLC SDU discard (only for UM and AM data transfer))

- RLC re-establishment

The MACs 1b-15 and 1b-30 are connected to several RLC layer devices configured in one terminal, and can perform operations of multiplexing RLC PDUs to MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. The main functions of MAC can be summarized as follows.

- Mapping between logical channels and transport channels

- Multiplexing/demultiplexing of MAC SDUs belonging to one or different logical channels into/from transport blocks (TB) delivered to/from the physical layer on transport channels

- Scheduling information reporting

- HARQ function (Error correction through HARQ (Hybrid Automatic Repeat Request))

- Priority handling between logical channels of one UE

- Priority handling between UEs by means of dynamic scheduling

- MBMS service identification

- Transport format selection

- Padding function (Padding)

The physical (PHY) layers 1b-20 and 1b-25 channel-code and modulate higher-layer data, make OFDM symbols and transmit them through a radio channel, or demodulate OFDM symbols received through a radio channel and channel-decode the upper layer data. You can perform the action of passing to the layer.

3 is a diagram showing the structure of a next-generation mobile communication system to which an embodiment is applied.

Referring to FIG. 3, the radio access network of the next-generation mobile communication system (hereinafter NR or 5g) includes a next-generation base station (New Radio Node B, hereinafter NR gNB or NR base station) 1c-10 and a next-generation radio core network (New Radio Core Network, NR CN) (1c-05). A next-generation radio user equipment (New Radio User Equipment, NR UE or terminal) 1c-15 can access an external network through the NR gNB 1c-10 and the NR CN 1c-05.

In FIG. 3, the NR gNB 1c-10 may correspond to an evolved Node B (eNB) of the existing LTE system. The NR gNB (1c-10) is connected to the NR UE (1c-15) through a radio channel, and can provide a superior service to the existing Node B. In a next-generation mobile communication system, all user traffic can be serviced through a shared channel. Therefore, a device for performing scheduling by collecting status information such as buffer status, available transmission power status, and channel status of UEs is required, and the NR gNB 1c-10 can take charge of this. One NR gNB (1c-10) can control multiple cells. In a next-generation mobile communication system, a bandwidth higher than the current maximum bandwidth may be applied in order to implement high-speed data transmission compared to current LTE. In addition, beamforming technology may be additionally applied by using Orthogonal Frequency Division Multiplexing (OFDM) as a radio access technology. In addition, an adaptive modulation & coding (AMC) method for determining a modulation scheme and a channel coding rate according to a channel condition of a terminal may be applied.

The NR CN 1c-05 may perform functions such as mobility support, bearer setup, and quality of service (QoS) setup. The NR CN 1c-05 is a device in charge of various control functions as well as a mobility management function for a terminal, and can be connected to a plurality of base stations. In addition, the next-generation mobile communication system can be interworked with the existing LTE system, and the NR CN (1c-05) can be connected to the MME (1c-25) through a network interface. The MME 1c-25 may be connected to the existing eNB 1c-30.

4 is a diagram showing a radio protocol structure of a next-generation mobile communication system to which an embodiment is applied.

Referring to FIG. 4, the wireless protocols of the next-generation mobile communication system are NR Service Data Adaptation Protocol (SDAP) (1d-01, 1d-45), NR PDCP (1d-05, 1d-40), NR RLC (1d-10, 1d-35), and NR MAC (1d-15, 1d-30).

The main functions of the NR SDAPs (1d-01, 1d-45) may include some of the following functions.

- Transfer of user plane data

- A mapping function between a QoS flow and a data bearer for uplink and downlink (mapping between a QoS flow and a DRB for both DL and UL)

- Marking QoS flow ID for uplink and downlink (marking QoS flow ID in both DL and UL packets)

- A function of mapping a relective QoS flow to a data bearer for uplink SDAP PDUs (reflective QoS flow to DRB mapping for the UL SDAP PDUs).

For the SDAP layer device, the UE uses a Radio Resource Control (RRC) message for each PDCP layer device, each bearer, or each logical channel, whether to use the header of the SDAP layer device or whether to use the function of the SDAP layer device can be set. When the SDAP header is set, the UE sets the Non-Access Stratum (NAS) Quality of Service (QoS) reflection setting 1-bit indicator (NAS reflective QoS) of the SDAP header and the Access Stratum (AS) QoS With the reflective setting 1-bit indicator (AS reflective QoS), the terminal may be instructed to update or reset mapping information for uplink and downlink QoS flows and data bearers. The SDAP header may include QoS flow ID information indicating QoS. QoS information may be used as data processing priority and scheduling information to support smooth service.

The main functions of the NR PDCP (1d-05, 1d-40) may include some of the following functions.

- Header compression and decompression (ROHC only)

- Transfer of user data

- In-sequence delivery of upper layer PDUs

- Out-of-sequence delivery of upper layer PDUs

- PDCP PDU reordering for reception

- Duplicate detection of lower layer SDUs

- Retransmission of PDCP SDUs

- Ciphering and deciphering

- Timer-based SDU discard in uplink.

In the above description, the reordering function of the NR PDCP device may refer to a function of reordering PDCP PDUs received from a lower layer in order based on a PDCP sequence number (SN). The reordering function of the NR PDCP device is a function to deliver data to the upper layer in the rearranged order, a function to directly deliver data without considering the order, a function to record lost PDCP PDUs by rearranging the order, and lost PDCP It may include at least one of a function of reporting the status of PDUs to the transmitter and a function of requesting retransmission of lost PDCP PDUs.

The main functions of NR RLC (1d-10, 1d-35) may include some of the following functions.

- Transfer of upper layer PDUs

- In-sequence delivery of upper layer PDUs

- Out-of-sequence delivery of upper layer PDUs

- ARQ function (Error Correction through ARQ)

- Concatenation, segmentation and reassembly of RLC SDUs

- Re-segmentation of RLC data PDUs

- Reordering of RLC data PDUs

- Duplicate detection

- Error detection function (Protocol error detection)

- RLC SDU discard function (RLC SDU discard)

- RLC re-establishment

In the above description, the in-sequence delivery function of the NR RLC device may refer to a function of sequentially delivering RLC SDUs received from a lower layer to an upper layer. Originally, when one RLC SDU is divided into several RLC SDUs and received, the in-sequence delivery function of the NR RLC device may include a function of reassembling and delivering them.

The in-sequence delivery function of the NR RLC device may include a function of rearranging received RLC PDUs based on an RLC sequence number (SN) or a PDCP sequence number (SN), and rearranging the order results in loss It may include at least one of a function of recording lost RLC PDUs, a function of reporting the status of lost RLC PDUs to the transmitter, and a function of requesting retransmission of lost RLC PDUs.

In-sequence delivery of the NR RLC device may include, when there is a lost RLC SDU, a function of sequentially delivering only RLC SDUs prior to the lost RLC SDU to a higher layer. In addition, the in-sequence delivery function of the NR RLC device, if a predetermined timer expires even if there is a lost RLC SDU, all RLC SDUs received before the timer starts are sequentially delivered to the upper layer. can do. In addition, the in-sequence delivery function of the NR RLC device may include a function of sequentially delivering all RLC SDUs received so far to the upper layer if a predetermined timer expires even if there is a lost RLC SDU. .

The NR RLC device may process RLC PDUs in the order in which they are received regardless of the order of sequence numbers (out-of sequence delivery) and deliver them to the NR PDCP device.

When the NR RLC device receives a segment, it may receive segments stored in a buffer or to be received later, reconstruct it into one complete RLC PDU, and then transmit it to the NR PDCP device.

The NR RLC layer may not include a concatenation function, and may perform a function in the NR MAC layer or may be replaced with a multiplexing function of the NR MAC layer.

In the above description, the out-of-sequence delivery of the NR RLC device may mean a function of immediately delivering RLC SDUs received from a lower layer to an upper layer regardless of order. Out-of-sequence delivery of the NR RLC device may include a function of reassembling and delivering, when originally one RLC SDU is divided into several RLC SDUs and received. The out-of-sequence delivery function of the NR RLC device may include a function of storing RLC SNs or PDCP SNs of received RLC PDUs and arranging the order to record lost RLC PDUs.

NR MACs (1d-15, 1d-30) may be connected to several NR RLC layer devices configured in one terminal, and the main functions of the NR MAC may include some of the following functions.

- Mapping between logical channels and transport channels

- Multiplexing/demultiplexing of MAC SDUs

- Scheduling information reporting

- HARQ function (Error correction through HARQ)

- Priority handling between logical channels of one UE

- Priority handling between UEs by means of dynamic scheduling

- MBMS service identification

- Transport format selection

- Padding function (Padding)

The NR PHY layers (1d-20, 1d-25) channel code and modulate higher layer data, convert OFDM symbols into OFDM symbols and transmit them through a radio channel, or demodulate OFDM symbols received through a radio channel and channel decode them to a higher layer. You can perform forwarding operations.

In addition, the NR PHY layer also uses HARQ for additional error correction, and the receiving end can transmit whether or not the packet transmitted by the transmitting end has been received with 1 bit. This is referred to as HARQ Acknowledgement (ACK)/Not-Acknowledgement (NACK) information. Downlink HARQ ACK/NACK information for uplink data transmission may be transmitted through a Physical Hybrid-ARQ Indicator Channel (PHICH) physical channel in case of LTE. In addition, in the case of NR, downlink HARQ ACK/NACK information for uplink data transmission is retransmitted through scheduling information of a corresponding terminal through PDCCH (Physical Dedicated Control CHannel), which is a channel through which downlink/uplink resource allocation is transmitted. You can determine if this is necessary, or if you just need to perform a new transfer. This is because asynchronous HARQ is applied in NR. Uplink HARQ ACK/NACK information for downlink data transmission may be transmitted through a Physical Uplink Control CHannel (PUCCH) or a Physical Uplink Shared CHannel (PUSCH) physical channel. Although the aforementioned PUCCH is generally transmitted in uplink of a PCell to be described later, the base station may be additionally transmitted to the terminal in an SCell to be described later when the terminal supports it, and this is referred to as a PUCCH SCell.

Meanwhile, the above-described NR PHY layer may be composed of one or a plurality of frequencies/carriers, and a technique of simultaneously setting and using a plurality of frequencies is called carrier aggregation (hereinafter referred to as CA). CA technology is a technology that uses only one carrier for communication between a UE (or User Equipment, UE) and a base station (E-UTRAN NodeB, eNB) in addition to a main carrier and one or more subcarriers. , the transmission amount can be dramatically increased by the number of subcarriers. Meanwhile, in LTE, a cell within a base station using a primary carrier is referred to as a primary cell or PCell (Primary Cell), and a cell within the base station using a subcarrier is referred to as a secondary cell or secondary cell (SCell).

5 is a diagram illustrating downlink and uplink channel frame structures of a next-generation mobile communication system to which an embodiment is applied. More specifically, FIG. 5 is a diagram illustrating downlink and uplink channel frame structures when beam-based communication is performed in a next-generation mobile communication system to which an embodiment of the present disclosure is applied.

Referring to FIG. 5, a base station (1e-01) transmits a signal in the form of a beam in order to transmit a wider coverage or stronger signal (1e-11) (1e-13) (1e-15) (1e-17) can do. Accordingly, the terminal 1e-03 within the cell may have to transmit and receive data using a specific beam transmitted by the base station (beam #1 (1e-13) as an example in this figure).

Meanwhile, depending on whether the terminal is connected to the base station (1e-01), the state of the terminal can be divided into RRC idle mode, RRC inactive mode, and RRC connected mode. there is. Accordingly, the base station 1e-01 may not know the location of the terminal in the RRC idle mode or the RRC inactive mode.

When a UE in RRC idle mode or RRC inactive mode wants to transition to RRC connected mode, the UE transmits a Synchronization Signal Block (SSB) (1e-21) (1e-23) transmitted by the base station (1e-01). ) (1e-25) (1e-27) can be received. The SSB may be an SSB signal transmitted periodically according to a period set by the base station 1e-01. The base station 1e-01 may set the SSB period through system information (eg, SIB1, SIB2) or dedicated RRC message signaling. Each SSB can be divided into a Primary Synchronization Signal (PSS) (1e-41), a Secondary Synchronization Signal (SSS) (1e-43), and a Physical Broadcast Channel (PBCH). .

5 exemplarily assumes a scenario in which SSBs are transmitted for each beam. For example, SSB#0 (1e-21) is transmitted using beam #0 (1e-11), and SSB#1 (1e-23) is transmitted using beam #1 (1e-13). and SSB#2 (1e-25) is transmitted using beam #2 (1e-15), and SSB#3 (1e-27) is transmitted using beam #3 (1e-17) was assumed. However, the present disclosure is not limited thereto and may be applied to various other scenarios.

In FIG. 5, it is exemplarily assumed that the terminal 1e-03 in the RRC idle mode or the RRC inactive mode is located on beam #1 (1e-13), and accordingly, the terminal 1e-03 is located on beam #1. SSB #1 (1e-23) transmitted as (1e-13) is received. Upon receiving SSB #1 (1e-23), the terminal can obtain a physical cell identifier (PCI) of the base station through PSS and SSS. In addition, by receiving the PBCH, the UE not only identifies the ID of the currently received SSB (i.e., #1) and the position within the 10 ms frame at which the SSB is currently received, but also the System Frame Number (SFN) having a period of 10.24 seconds. You can figure out which SFN you are in within.

In addition, the above-described PBCH may include a Master Information Block (MIB), and the MIB may indicate at which location a System Information Block type 1 (SIB1) broadcasting more detailed cell configuration information may be received. Upon receiving SIB1, the UE can know the total number of SSBs transmitted by the base station and can identify a Physical Random Access CHannel (PRACH) occasion capable of transmitting a preamble, which is a physical signal specially designed to match uplink synchronization.

In FIG. 5, it is assumed that PRACH occasions (1e-30 to 1e-39) are assigned every 1 ms. In addition, based on the above-described information, the UE can know which PRACH occasion among PRACH occasions is mapped to which SSB index. For example, in FIG. 5, a scenario in which PRACH occasions are allocated every 1 ms is assumed, and a scenario in which 1/2 SSBs are allocated per PRACH occasion (ie, 2 PRACH occasions per SSB) is assumed. Accordingly, in FIG. 5, a scenario in which two PRACH occasions are allocated for each SSB from the start of the PRACH occasion starting according to the SFN value is shown.

That is, exemplarily, the PRACH occasion (1e-30) (1e-31) is allocated for SSB#0, the PRACH occasion (1e-32) (1e-33) is allocated for SSB#1, and the PRACH occasion (1e-34) (1e-35) may be allocated for SSB#2, and PRACH occasion (1e-36) (1e-37) may be allocated for SSB#3. PRACH occasions are set for all SSBs, and PRACH occasions (1e-38) (1e-39) may be allocated for the first SSB.

Accordingly, the UE recognizes the location of the PRACH occasion (1e-32) (1e-33) for SSB #1, and at the current time point among the PRACH occasion (1e-32) (1e-33) corresponding to SSB #1. A random access preamble may be transmitted on the earliest PRACH occasion (eg, (1e-32)). Since the base station receives the preamble on the PRACH occasion (1e-32), it can be known that the corresponding terminal selected SSB #1 and transmitted the preamble, and accordingly, when performing subsequent random access, data can be transmitted and received through the corresponding beam. can

6 is a diagram for explaining a procedure for repeatedly transmitting Msg3 (Message 3) when a terminal performs random access to a base station in a next-generation mobile communication system to which an embodiment is applied. More specifically, FIG. 6 shows when a terminal in RRC idle mode or RRC inactive mode performs random access to a base station in a next-generation mobile communication system according to an embodiment of the present disclosure, It is a diagram for explaining a procedure of repeatedly transmitting Msg3.

In this figure, a contention-based random access procedure is mainly described. On the other hand, in the contention-free random access procedure, there is a procedure for allocating a dedicated random access resource in step 1f-09 in order for the base station 1f-03 to perform contention-free random access to the terminal 1f-01. can

In an embodiment of the present disclosure, when a UE in an RRC idle mode or an RRC inactive mode performs random access, the base station transmits a random access preamble to system information (e.g., MIB1, SIB1, SIB2) repeatedly. Alternatively, an information element may be included, or an indicator or information element to repeatedly transmit Msg3 may be included. If there is an indicator or information element described above, the terminal may repeatedly transmit random access or transmit Msg3 repeatedly (TTI bundling, uplink bundling repetition) accordingly. In addition, in an embodiment of the present disclosure, the base station may allocate a separate dedicated random access resource for repeatedly transmitting Msg3 when a terminal in an RRC idle mode or an RRC inactive mode performs random access. In an embodiment, information on the proposed separate dedicated random access resource may be one or more of the following.

1. Separate/dedicated PRACH occasions for transmission of Msg3 during Random Access

2. Specific preamble index (ra-PreambleIndex for transmission of Msg3 during Random Access)

3. New or dedicated Random Access Preamble group for transmission of Msg3 during Random Access

4. PRACH resource on a specific time/frequency for repeatedly transmitting Msg3 when performing random access

5. Information Element (IE) for how many times the random access preamble can be repeatedly transmitted or an indicator for whether the random access preamble can be repeatedly transmitted a fixed number of times

The base station may allocate information on the proposed separate dedicated random access resource to the terminal through a PDCCH, transmit it through an RRC layer message, or broadcast it through system information. Accordingly, if there is a separate dedicated random access resource as described above allocated from the base station for the random access procedure currently performed by the terminal in the RRC idle mode or the RRC inactive mode, the terminal uses the random access resource through the corresponding random access resource. An access preamble may be transmitted. In an embodiment of the present disclosure, a terminal in an RRC idle mode or an RRC inactive mode may repeatedly transmit a random access preamble through a corresponding random access resource. The above-described embodiment can be equally applied to a contention-based random access procedure to be described later. In the non-contention based random access, if there is a preamble transmitted by the UE in the RAR message to be described later, it is determined that the random access is successfully completed and the random access procedure can be terminated.

The following description will explain the contention-based random access procedure.

First, in step 1f-71, the terminal 1f-01 in the RRC idle mode or the RRC inactive mode may trigger random access to access the base station 2f-03.

When random access is triggered, in step 1f-63, as described with reference to FIG. 5, the terminal 1f-01 first determines which beam should be used to transmit/receive data including random access, and accordingly SSB can choose The SSB selection method according to this embodiment may be one of the following.

1. Among the received SSBs, the terminal randomly selects one of SSBs whose signal strength exceeds a predetermined threshold set by the base station in the system information or RRC layer message.

2. Among the SSBs received, the terminal selects the SSB with the highest signal strength among SSBs whose signal strength exceeds a predetermined threshold set by the base station in the system information or RRC layer message.

3. Among the SSBs received, the terminal exceeds a predetermined threshold set by the base station in the above-described system information or RRC layer message, and in order to repeatedly transmit Msg3, one SSB index or a plurality of SSBs indicated separately One of the SSBs matching the SSB index is randomly selected or the SSB having the highest signal strength among them is selected.

For example, in FIG. 5, although the terminal receives all of SSB #0, SSB #1, and SSB #2, only the signal strength of SSB #1 exceeds the aforementioned threshold, and the signal strength of SSB #0 and SSB #2 If it does not exceed the above-mentioned threshold, the terminal can select SSB #1. In the embodiment described with reference to FIG. 6, the base station transmits system information (eg, MIB1, SIB1, SIB2) including a separate threshold for repeatedly transmitting Msg3 or an RRC layer message (eg, RRCRelease message, RRCReconfiguration message, RRCReestablishment message) may be transmitted to the terminal. At this time, the base station indicates the above-described information or message with a value of RSRP (Reference Signal Received Power) of SSB or RSRP of CSI-RS (Channel State Information-Reference Signal), such as rsrp-thresholdSSB or rsrp-ThresholdCSI-RS. can

As described above, when SSB is selected, UE 1f-01 can know a separate dedicated PRACH occasion for repeatedly transmitting Msg3 mapped to the selected SSB. Accordingly, the UE 1f-01 may transmit a random access preamble to the base station on the corresponding PRACH occasion in step 1f-11. In an embodiment, the operation of step 1f-11 may be one or more of the following.

1. One random access preamble is transmitted on a separate dedicated PRACH occasion.

2. If there is an Information Element (IE) on how many times the random access preamble can be repeatedly transmitted in the system information or an indicator on whether the random access preamble can be repeatedly transmitted a fixed number of times, a separate A random access preamble is transmitted on a dedicated PRACH occasion of

3. If a new or separate random access preamble group is set from the system information, one random access preamble is transmitted in the corresponding random access preamble group.

In the above condition, a case in which one or more UEs simultaneously transmit random access preambles may occur on a PRACH occasion. PRACH resources may span one subframe, or only some symbols within one subframe may be used. In addition, the random access preamble is a specific sequence specially designed to be received even if it is transmitted before being completely synchronized with the base station, and may have a plurality of preamble identifiers (indexes) according to the standard. When there are a plurality of preamble identifiers, the preamble transmitted by the terminal may be randomly selected by the terminal or may be a specific preamble designated by the base station.

Meanwhile, when a terminal already in connected mode performs random access and the base station has set a specific signal to be measured, the process of selecting the above-described SSB is based on the specific signal to be measured instead of the above-described SSB PRACH. It may be an operation of selecting an occasion. The above-described specific signal to be measured may be SSB or Channel State Information Reference Signal (CSI-RS). For example, when handover is performed to another base station due to movement of the terminal, a handover command may select a PRACH occasion mapped to the SSB or CSI-RS of the target base station, and accordingly, the terminal measures the configured signal. Therefore, it is possible to determine on which PRACH occasion the random access preamble is to be transmitted.

When the base station receives the above-described preamble (or the preamble transmitted by another terminal), in step 1f-21, the base station 1f-03 sends a Random Access Response (RAR) message to the terminal It can be transmitted to (1f-01). In the embodiment described with reference to FIG. 6 , the time point at which the base station 1f-03 transmits the RAR message to the terminal 1f-01 may be one of the following.

1. When the first preamble is received, a random access response message is transmitted to the terminal.

2. When the last preamble is received, a random access response message is transmitted to the terminal.

3. When any preamble is received, a random access response message is transmitted to the terminal.

The above-described RAR message includes preamble identifier information used in step 1f-11, uplink transmission timing correction information, uplink resource allocation information to be used in a subsequent step (ie, step 1f-31), and temporary terminal identifier information. At least one may be included. The identifier information of the above-described preamble is transmitted to inform which preamble the response message is for the above-described RAR message, for example, when a plurality of terminals transmit different preambles and attempt random access in step 1f-11 It can be. The above-described uplink resource allocation information may be detailed information of a resource to be used by the terminal 1f-01 by repeating Msg3 in step 1f-31 to be described later, and the physical location and size of the resource, and a decoding and coding method used during transmission. (modulation and coding scheme, MCS) and power adjustment information during transmission may be included.

In addition, the base station (1f-03) may include a 1-bit indicator in the RAR message, instructing the terminal (1f-01) to repeatedly transmit Msg3 together with uplink resource allocation information for the terminal (1f-01) to repeatedly transmit Msg3. can In addition, the base station 1f-03 may transmit the RAR message including a value indicating how many times the terminal can repeatedly transmit Msg3.

The above-described temporary terminal identifier information is used when the terminal transmitting the preamble makes an initial access, since the terminal does not have an identifier allocated by the base station for communication with the base station 1f-03. value to be transmitted.

Meanwhile, the base station 1f-03 determines that, for example, the number of preambles received through the PRACH for a certain period of time exceeds a predetermined number based on the amount of energy of the PRACH received or the number of preambles received through the PRACH during a certain period of time. When it is determined that, it may be determined that there are too many terminals performing random access. At this time, the base station 1f-03 may receive a subheader including Backoff Indicator information in the aforementioned RAR message. The aforementioned subheader may be located at the very beginning of the aforementioned RAR message. The aforementioned Backoff Indicator has a size of 4 bits and may have the following values.

If the terminal does not receive a response to the preamble transmitted within the 'RAR window' (1f-51) period and receives only the above-described Backoff Indicator information, the terminal receives a random value between the above-described received value and 0 when retransmitting the preamble. By selecting a number, the preamble retransmission time can be delayed (1f-61) by the selected time.

The above-described RAR message must be transmitted within a predetermined period starting from a predetermined time after the above-described preamble is sent, and the above-described period is referred to as 'RAR window (1f-51) (1f-53)'. In the embodiment described with reference to FIG. 6, the above-described starting point of the RAR window may be as follows.

1. The RAR window starts when a predetermined time elapses after the first preamble is transmitted.

2. The RAR window starts when a predetermined time has elapsed since the last preamble was transmitted.

3. The RAR window starts when a predetermined time elapses after each preamble is transmitted.

The aforementioned predetermined time may have a subframe unit (2 ms) or a smaller value. In addition, the length of the RAR window may be a predetermined value set by the base station for each PRACH resource or one or more PRACH resource sets within system information broadcast by the base station. Also, the starting point of the RAR window may be included in system information broadcast by the base station.

Meanwhile, when the above-described RAR message is transmitted, the base station may schedule the corresponding RAR message through PDCCH, and the corresponding scheduling information may be scrambled using RA-RNTI (Random Access-Radio Network Temporary Identifier). The aforementioned RA-RNTI may be mapped with the PRACH resource used to transmit the message in step 1f-11. A UE that has transmitted a preamble to a specific PRACH resource can determine whether there is a corresponding RAR message by attempting PDCCH reception based on the corresponding RA-RNTI. That is, if the above-described RAR message is a response to the preamble transmitted by the UE in step 1f-11 as shown in FIG. 6, the RA-RNTI used in the RAR message scheduling information is It may contain information about the transmission. To this end, RA-RNTI can be calculated as in the following equation.

In this case, in Equation 1, s_id is an index corresponding to the first OFDM symbol in which the preamble transmission in step 1f-11 starts, and may have a value of 0 = s_id < 14 (ie, the maximum number of OFDMs in one slot) . In addition, t_id is an index corresponding to the first slot where the preamble transmission started in step 1f-11, and may have a value of 0 = t_id < 80 (that is, the maximum number of slots within one system frame (20 ms)). In addition, the above-described f_id indicates which PRACH resource in which the preamble transmitted in step 1f-11 was transmitted in frequency, and has a value of 0 = f_id < 8 (ie, the maximum number of PRACHs in frequency within the same time). can have In addition, the above-mentioned ul_carrier_id indicates whether the above-described preamble was transmitted in the basic uplink (Normal Uplink, NUL) when two carriers are used for uplink for one cell (in this case, 0), and supplementary uplink (Supplementary Uplink, SUL). ) is a factor for distinguishing whether the above-described preamble has been transmitted (1 in this case).

In FIG. 6, a scenario is assumed in which the terminal receives the RAR message with the RA-RNTI corresponding to the preamble transmission in step 1f-11, but does not include the identifier corresponding to the transmitted preamble. That is, for example, it may be the case that the terminal transmits preamble 7 out of a total of 64 preamble identifiers, but the RAR message received from the base station includes only a response to preamble 4. Accordingly, as described above, if there is a BI value received upon retransmission of the preamble, the terminal may delay (1f-61) by a value randomly selected from the corresponding value. Also, in order to retransmit the preamble, the UE may select the SSB again at a corresponding time point in step 1f-65.

In step 1f-13, the UE may retransmit the preamble on the corresponding PRACH occasion according to the selected SSB. In addition, it can wait for a response in step 1f-53 and receive it in step 1f-23. If there are many terminals performing random access, as described above, the preamble transmission is distributed over time, so that the random access success probability can be increased.

In addition, when the UE retransmits the preamble described above in step 1f-23, the transmission power for transmitting the preamble is increased by the corresponding power compared to the previously transmitted preamble in step 1f-11 according to the value set by the base station (preamblePowerRampingStep). can be retransmitted with the specified power (power ramping). Accordingly, as the number of retransmissions increases, the transmit power continues to increase and is transmitted until the terminal reaches the maximum transmit power, so that the probability of reaching the base station increases.

In step 1f-31, the terminal receiving the RAR message for the transmitted preamble may transmit other messages according to the above-mentioned various purposes on the resources allocated to the above-mentioned RAR message. Referring to FIG. 6, the third transmitted message may be referred to as Msg3 (that is, the preamble of step 1f-11 or step 1f-13 may be referred to as Msg1, and the RAR of step 1f-21 may be referred to as Msg2). The terminal may repeatedly transmit Msg3 based on information on how many times Msg3 should be repeatedly transmitted in system information, an RRC layer message, or an RAR message. Also, when the UE transmits the random access preamble to the BS in a separate dedicated PRACH resource, it can repeatedly transmit Msg3 to the BS.

Msg3 transmitted by the terminal may be an RRCSetupRequest message or an RRCResumeRequest message, which is an RRC layer message, in case of initial access, an RRCReestablishmentRequest message in case of reconnection, and an RRCReconfigurationComplete message in case of handover. can be Alternatively, a Buffer Status Report (BSR) message for requesting resources may be transmitted. A logical channel through which the terminal sends Msg3 to the base station may include a Common Control CHannel (CCCH) and a Common Control CHannel (CCCH1), respectively. Therefore, the procedure according to this embodiment may be applied only to CCCH, CCCH1, or both. The terminal may configure Msg3 according to the above conditions and transmit it to the base station. For example, when the terminal repeatedly transmits Msg3 in step 1f-31, the terminal may drive ra-ContentionResolutionTimer. In an embodiment, the driving time point proposed in the present disclosure may be one of the following.

1. When Msg3 is sent for the first time, ra-ContentionResolutionTimer is driven.

2. When the last Msg3 is sent, ra-ContentionResolutionTimer is driven.

3. Every time Msg3 is sent, ra-ContentionResolutionTimer is driven.

Meanwhile, the reason for performing random access for each terminal may be different. As described above, there may be various reasons such as initial access (which may include initial access for high-priority traffic), handover, and reset due to RRC layer connection failure. In addition, in a system using high frequency Random access can also be used when recovering from a beam failure in which transmission fails because the direction of the transmission beam does not match the direction of the terminal. When recovering from handover and beam failure, faster random access may be required. This is to minimize the user's inconvenience since the terminal is disconnected after already communicating.

Accordingly, when the terminal performs random access to recover from handover or beam failure, values different from those for normal random access may be used for the aforementioned backoff indicator and power ramping values. For example, if a shorter value is used for the backoff indicator and a larger value is used for the power ramping value, the random access success time and probability can be further increased. Parameters for giving high priority in this way are collectively referred to as high-priority access parameters (HighPriorityAccess, HPA).

In addition, in the case of beam failure recovery, the terminal may perform a corresponding operation not only in the PCell but also in the SCell, and accordingly, the above-described HPA parameters may be commonly signaled and applied to all serving cells. Other general random access parameters (the aforementioned RAR window size, power ramping size, and maximum number of preamble transmissions) can be separately set by the base station for each serving cell.

7 is a diagram for explaining a procedure for transmitting Msg3 when a terminal performs random access to a base station in a next-generation mobile communication system to which an embodiment is applied. More specifically, FIG. 7 is a URLLC when a terminal in RRC idle mode or RRC inactive mode performs random access to a base station in a next-generation mobile communication system according to an embodiment of the present disclosure. (Ultra Reliable Low Latency Communication) This is a diagram to explain the procedure of transmitting Msg3 by applying the MCS introduced for the service.

In an embodiment, an MCS table introduced for a URLLC service supporting 64 QAM is as follows.

7 mainly describes a contention-based random access procedure. In the non-contention-based random access procedure, the procedure for allocating dedicated random access resources in step 1g-09 is performed before the random access in order for the base station 1g-03 to perform non-contention-based random access to the terminal 1g-01. can exist in

In the embodiment described with reference to FIG. 7, the base station, when the terminal in the RRC idle mode or the RRC inactive mode performs random access, the random access preamble to system information (eg, MIB1, SIB1, SIB2) An indicator or information element to repeat transmission may be included. If there is a corresponding indicator or information element, the terminal may repeatedly transmit random access accordingly. In addition, in the embodiment of FIG. 7, the base station is a separate dedicated random access resource for transmitting Msg3 by applying the MCS introduced for the URLLC service when the terminal in the RRC idle mode or the RRC inactive mode performs random access. can be assigned. In an embodiment, information on a separate dedicated random access resource may be one or a plurality of the following.

6. Separate/dedicated PRACH occasions for transmission of Msg3 applying new MCS table during Random Access

7. Specific preamble index (ra-PreambleIndex for transmission of Msg3 applying new MCS table during Random Access)

8. New or dedicated Random Access Preamble group for transmission of Msg3 applying applying new MCS table during Random Access

9. PRACH resource on a specific time/frequency for transmitting Msg3 by applying MCS introduced for URLLC service when performing random access

10. Information Element (IE) for how many times the random access preamble can be repeatedly transmitted or an indicator for whether the random access preamble can be repeatedly transmitted a fixed number of times

The base station may allocate information on the proposed separate dedicated random access resource to the terminal through a PDCCH, transmit it through an RRC layer message, or broadcast it through system information. Accordingly, if there is a separate dedicated random access resource (as described above) allocated from the base station for the random access procedure currently performed by the terminal in the RRC idle mode or the RRC inactive mode, the terminal uses the corresponding random access resource. A random access preamble may be transmitted. In the embodiment of FIG. 7 , a terminal in an RRC idle mode or an RRC inactive mode may repeatedly transmit a random access preamble through a corresponding random access resource. The content of this embodiment can be equally applied to a contention-based random access procedure to be described later. Meanwhile, in the non-contention based random access, if there is a preamble transmitted by the UE in the RAR message to be described later, it is determined that the random access is successfully completed and the random access procedure can be terminated.

The following description will explain the contention-based random access procedure.

First, in step 1g-71, the terminal 1g-01 in the RRC idle mode or the RRC inactive mode may trigger random access to access the base station 2g-03. When random access is triggered, as described above, in step 1g-63, the terminal first determines which beam should be used to transmit/receive data including random access, and selects an SSB accordingly. An SSB selection method according to an embodiment may be one of the following.

4. From among the received SSBs, the terminal randomly selects one of SSBs whose signal strength exceeds a predetermined threshold set by the base station in the above-described system information or RRC layer message.

5. Among the SSBs received, the terminal selects the SSB with the highest signal strength among SSBs whose signal strength exceeds a predetermined threshold set by the base station in the above-described system information or RRC layer message.

6. Among the SSBs received, the terminal exceeds a predetermined threshold set by the base station in the above-described system information or RRC layer message, applies MCS introduced for URLLC service, and separately indicates to transmit Msg3 One of the SSB indexes corresponding to one SSB index or a plurality of SSB indexes is randomly selected or the SSB having the highest signal strength among them is selected.

For example, in FIG. 5, although the terminal receives all of SSB #0, SSB #1, and SSB #2, only the signal strength of SSB #1 exceeds the aforementioned threshold, and the signal strength of SSB #0 and SSB #2 If it does not exceed the above-mentioned threshold, the terminal can select SSB #1. In the embodiment described with reference to FIG. 7, the base station applies MCS table 3 and includes a separate threshold for transmitting Msg3, including system information (eg MIB1, SIB1, SIB2) or RRC layer messages (eg For example, an RRCRelease message, an RRCReconfiguration message, and an RRCReestablishment message) may be transmitted to the terminal. At this time, the base station may indicate the above-described information or message with a value of RSRP of SSB or RSRP of CSI-RS, such as rsrp-thresholdSSB or rsrp-ThresholdCSI-RS.

As described above, when SSB is selected, the UE can know a separate dedicated PRACH occasion for transmitting Msg3 mapped to the selected SSB by applying the MCS introduced for the URLLC service. In an embodiment, an operation (step 1g-11) of transmitting a random access preamble from a UE to a base station on a corresponding PRACH occasion may be one or a plurality of the following.

3. One random access preamble is transmitted on a separate dedicated PRACH occasion.

2. If there is an Information Element (IE) on how many times the random access preamble can be repeatedly transmitted or an indicator on whether the random access preamble can be repeatedly transmitted a fixed number of times in the system information, based on the information A random access preamble is transmitted on a dedicated PRACH occasion of

4. If a new or separate random access preamble group is set from the system information, one random access preamble is transmitted in the corresponding random access preamble group.

In the above condition, a case in which one or more UEs simultaneously transmit random access preambles may occur on a PRACH occasion. PRACH resources may span one subframe, or only some symbols within one subframe may be used. In addition, the random access preamble is a specific sequence specially designed to be received even if it is transmitted before completely synchronizing with the base station, and may have a plurality of preamble identifiers (indexes) according to the standard. When there are a plurality of preamble identifiers, the preamble transmitted by the terminal may be randomly selected by the terminal or may be a specific preamble designated by the base station.

On the other hand, when a terminal already in a connected mode performs random access, the process of selecting the above-described SSB is PRACH based on the specific signal to be measured instead of the above-described SSB when the base station has set a specific signal to be measured. It may be an operation of selecting an occasion. In an embodiment, a specific signal to be measured may be SSB or Channel State Information Reference Signal (CSI-RS). For example, when handover is performed to another base station due to movement of the terminal, a handover command may select a PRACH occasion mapped to the SSB or CSI-RS of the target base station, and accordingly, the terminal measures the configured signal. Accordingly, it is possible to determine which PRACH occasion to transmit the random access preamble.

When the base station receives the above-described preamble (or the preamble transmitted by another terminal), in step 1g-21, a random access response (RAR) message for this can be transmitted to the terminal. In the embodiment described with reference to FIG. 7, the time point at which the base station transmits the RAR message to the terminal may be one of the following.

4. When the first preamble is received, a random access response message is transmitted to the terminal.

5. When the last preamble is received, a random access response message is transmitted to the terminal.

6. When any preamble is received, a random access response message is transmitted to the terminal.

The above-described RAR message includes preamble identifier information used in step 1g-11, uplink transmission timing correction information, uplink resource allocation information to be used in a later step (ie, step 1g-31), and temporary terminal identifier information. At least one may be included. The identifier information of the above-described preamble is transmitted to inform which preamble the response message is for the above-described RAR message, for example, when a plurality of terminals transmit different preambles and attempt random access in step 1g-11 It can be. The above-described uplink resource allocation information may be detailed information of resources to use Msg3 by applying the MCS table introduced for the URLLC service by the terminal in step 1g-31, physical location and size of the resource, decoding and A coding method (modulation and coding scheme, MCS), power adjustment information during transmission, and the like may be included.

In addition, the base station may include a 1-bit indicator in the RAR message, instructing the terminal to repeatedly transmit Msg3 to the terminal together with uplink resource allocation information to be transmitted by applying the MCS table introduced for the URLLC service. In addition, the base station may transmit the RAR message including a value indicating how many times the terminal can repeatedly transmit Msg3.

The above-described temporary UE identifier information is a value transmitted for use in the case where the UE transmitting the preamble performs an initial access, since the UE does not have an identifier assigned by the base station for communication with the base station.

Meanwhile, when the base station determines that the number of preambles received through the PRACH during a certain time is greater than or equal to a predetermined number based on the amount of energy of the PRACH received or the number of preambles received through the PRACH during a certain time, for example, It may be determined that there are too many terminals performing random access. At this time, the base station may receive a subheader including Backoff Indicator information in the aforementioned RAR message. The aforementioned subheader may be located at the very beginning of the aforementioned RAR message. The aforementioned Backoff Indicator has a size of 4 bits and may have the following values.

If the terminal does not receive a response to the transmitted preamble within the 'RAR window' (1g-51) period and receives only the above-described Backoff Indicator information, the terminal retransmits the preamble, the above-described received value and By selecting an arbitrary number between 0, the preamble retransmission time can be delayed (1g-61) by the selected time.

The above-described RAR message must be transmitted within a predetermined period starting from a predetermined time after the above-described preamble is sent, and the above-described period is referred to as 'RAR window (1g-51) (1g-53)'. In the embodiment described with reference to FIG. 7 , the above-described starting point of the RAR window may be as follows.

4. The RAR window starts when a predetermined time elapses after the first preamble is transmitted.

5. The RAR window starts when a predetermined time has elapsed since the last preamble was transmitted.

6. The RAR window starts when a predetermined time elapses after each preamble is transmitted.

The aforementioned predetermined time may have a subframe unit (2 ms) or a smaller value. In addition, the length of the RAR window may be a predetermined value set by the base station for each PRACH resource or one or more PRACH resource sets within system information broadcast by the base station. Also, the starting point of the RAR window may be included in system information broadcast by the base station.

Meanwhile, when the above-described RAR message is transmitted, the base station may schedule the corresponding RAR message through PDCCH, and the corresponding scheduling information may be scrambled using RA-RNTI (Random Access-Radio Network Temporary Identifier). The aforementioned RA-RNTI may be mapped with the PRACH resource used to transmit the message in step 1g-11. A UE that has transmitted a preamble to a specific PRACH resource can determine whether there is a corresponding RAR message by attempting PDCCH reception based on the corresponding RA-RNTI. That is, if the above-described RAR message is a response to the preamble transmitted by the UE in step 1g-11 as shown in FIG. 7, the RA-RNTI used in the RAR message scheduling information is It may contain information about the transmission. To this end, RA-RNTI can be calculated as in the following equation.

In this case, in Equation 2, s_id is an index corresponding to the first OFDM symbol from which the preamble transmission transmitted in step 1g-11 started, and may have a value of 0 = s_id < 14 (ie, the maximum number of OFDMs in one slot) . In addition, t_id is an index corresponding to the first slot in which the preamble transmission transmitted in step 1g-11 starts, and may have a value of 0 = t_id < 80 (that is, the maximum number of slots within one system frame (20 ms)). In addition, the above-described f_id indicates which frequency PRACH resource the preamble transmitted in step 1g-11 is transmitted, and has a value of 0 = f_id < 8 (ie, the maximum number of PRACHs on frequency within the same time period). can In addition, the above-described ul_carrier_id indicates whether the above-described preamble was transmitted in Normal Uplink (NUL) when two carriers are used for uplink for one cell (in this case, 0) or supplementary uplink (Supplementary Uplink, SUL). ) is a factor for distinguishing whether the preamble described above has been transmitted (1 in this case).

In FIG. 7, it is assumed that the UE receives the RAR message with the RA-RNTI corresponding to the preamble transmission of step 1g-11 described above, but does not include the identifier corresponding to the transmitted preamble. That is, for example, it may be the case that the terminal transmits preamble 7 out of a total of 64 preamble identifiers, but the RAR message received from the base station includes only a response to preamble 4. Accordingly, as described above, if there is a BI value received when retransmitting the preamble, the terminal may delay the BI value by a value randomly selected from the corresponding value in step 1g-61, and in order to retransmit the preamble, at the corresponding time point in step 1g-65. You can select SSB again from . In addition, in step 1g-13, the UE may retransmit the preamble at the corresponding PRACH occasion according to the selected SSB, wait for a response in step 1g-53, and receive a response in step 1g-23. Accordingly, if there are many terminals performing random access, the preamble transmission is distributed over time, so that the random access success probability can be increased.

In addition, when the UE retransmits the preamble described above in step 1g-31, the transmission power for transmitting the preamble is equal to the corresponding power according to the value set by the base station (preamblePowerRampingStep) compared to the previously transmitted preamble in step 1g-11. It can be retransmitted with increased power (power ramping). Accordingly, as the number of retransmissions increases, the preamble transmission power can be continuously increased and transmitted until it reaches the maximum transmission power of the terminal, so that the probability of the signal reaching the base station increases.

Upon receiving the RAR message for the transmitted preamble, the terminal may transmit other messages according to the above-described various purposes in the resources allocated to the above-described RAR message in step 1g-31. Referring to FIG. 7, the third transmitted message may be referred to as Msg3 (that is, the preamble of step 1g-11 or step 1g-13 may be referred to as Msg1, and the RAR of step 1g-21 may be referred to as Msg2). When Msg3 is transmitted by applying the MCS table introduced for the URLLC service to system information, RRC layer messages, and RAR messages, the terminal applies the MCS table introduced for the URLLC service to transmit Msg3. can transmit. In addition, when a random access preamble is transmitted to the base station in a separate dedicated PRACH resource, the terminal may transmit Msg3 to the base station by applying the MCS table introduced for the URLLC service. Msg3 transmitted by the terminal may be an RRCSetupRequest message or RRCResumeRequest message, which is an RRC layer message, in case of initial access, an RRCReestablishmentRequest message in case of reconnection, and an RRCReconfigurationComplete message in case of handover. Alternatively, a Buffer Status Report (BSR) message for requesting resources may be transmitted. A logical channel through which the terminal sends Msg3 to the base station may include a Common Control CHannel (CCCH) and a Common Control CHannel (CCCH1), respectively. Therefore, the above-described procedure may be applied only to CCCH, CCCH1, or both. The terminal may configure Msg3 according to the above conditions and transmit it to the base station.

In step 1g-31, when the terminal repeatedly transmits Msg3 or transmits Msg3 by applying the MCS table introduced for the URLLC service or repeatedly transmits Msg3 by applying the MCS table introduced for the URLLC service, the ra-ContentionResolutionTimer can drive The driving time point proposed in the present disclosure may be one of the following.

4. When Msg3 is first sent, ra-ContentionResolutionTimer is driven.

5. When the last Msg3 is sent, ra-ContentionResolutionTimer is driven.

6. Every time Msg3 is sent, ra-ContentionResolutionTimer is driven.

Meanwhile, the reason for performing random access for each terminal may be different. As described above, there may be various reasons such as initial access (which may include initial access for high-priority traffic), handover, and reset due to RRC layer connection failure. In addition, in a system using high frequency Random access can also be used when recovering from a beam failure in which transmission fails because the direction of the transmission beam does not match the direction of the terminal. When recovering from handover and beam failure, faster random access may be required. This is to minimize the user's inconvenience since the terminal is disconnected after already communicating.

Accordingly, when the terminal performs random access to recover from handover or beam failure, values different from those for normal random access may be used for the aforementioned backoff indicator and power ramping values. For example, if a shorter value is used for the backoff indicator and a larger value is used for the power ramping value, the random access success time and probability can be further increased. Parameters for giving high priority in this way are collectively referred to as high-priority access parameters (HighPriorityAccess, HPA).

In addition, in the case of the above-described beam failure recovery, the terminal may perform a corresponding operation not only in the PCell but also in the SCell, and accordingly, the above-described HPA parameter may be commonly signaled and applied to all serving cells. Other general random access parameters (the aforementioned RAR window size, power ramping size, and maximum number of preamble transmissions) can be separately set by the base station for each serving cell.

The embodiments described with reference to FIGS. 6 and 7 are not mutually exclusive and may be applied together.

8 is a block diagram illustrating the structure of a terminal according to an embodiment of the present disclosure.

The terminal may include a radio frequency (RF) processing unit 1h-10, a baseband processing unit 1h-20, a storage unit 1h-30, and a control unit 1h-40.

The RF processor 1h-10 according to an embodiment of the present disclosure may perform functions for transmitting and receiving signals through a wireless channel, such as band conversion and amplification of signals. That is, the RF processing unit 1h-10 up-converts the baseband signal provided from the baseband processing unit 1h-20 into an RF band signal, transmits the signal through an antenna, and converts the RF band signal received through the antenna into a baseband signal. can be down-converted to a signal. For example, the RF processor 1h-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital to analog converter (DAC), an analog to digital converter (ADC), and the like. there is.

In FIG. 8, only one antenna is shown, but a terminal may include multiple antennas.

Also, the RF processor 1h-10 may include a plurality of RF chains. Furthermore, the RF processor 1h-10 may perform beamforming. For beamforming, the RF processing unit 1h-10 may adjust the phase and size of signals transmitted and received through a plurality of antennas or antenna elements. In addition, the RF processor 1h-10 may perform Multiple-Input Multiple-Output (MIMO), and may receive multiple layers when performing the MIMO operation. The RF processing unit 1h-10 appropriately sets a plurality of antennas or antenna elements under the control of the control unit 1h-40 to perform reception beam sweeping, or adjusts the direction and beam of the reception beam so that the reception beam is coordinated with the transmission beam. Width can be adjusted.

The baseband processor 1h-20 may perform a conversion function between a baseband signal and a bit string according to the physical layer standard of the system. For example, during data transmission, the baseband processing unit 1h-20 may generate complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit 1h-20 may restore the received bit string through demodulation and decoding of the baseband signal provided from the RF processing unit 1h-10. For example, in the case of orthogonal frequency division multiplexing (OFDM), during data transmission, the baseband processing unit 1h-20 encodes and modulates a transmission bit stream to generate complex symbols, and maps the complex symbols to subcarriers. After that, OFDM symbols may be configured through inverse fast Fourier transform (IFFT) operation and cyclic prefix (CP) insertion. In addition, when receiving data, the baseband processing unit 1h-20 divides the baseband signal provided from the RF processing unit 1h-10 into OFDM symbol units, and maps the baseband signals to subcarriers through a fast Fourier transform (FFT) operation. After restoring the signals, a received bit stream may be restored through demodulation and decoding.

The baseband processing unit 1h-20 and the RF processing unit 1h-10 may transmit and receive signals as described above. Accordingly, the baseband processing unit 1h-20 and the RF processing unit 1h-10 may be referred to as a transmitter, a receiver, a transceiver, or a communication unit. Furthermore, at least one of the baseband processing unit 1h-20 and the RF processing unit 1h-10 may include a plurality of communication modules to support a plurality of different wireless access technologies. In addition, at least one of the baseband processing unit 1h-20 and the RF processing unit 1h-10 may include different communication modules to process signals of different frequency bands. For example, different radio access technologies may include an LTE network, a NR network, and the like. In addition, the different frequency bands may include a super high frequency (SHF) (eg, 2.2gHz, 2ghz) band and a millimeter wave (eg, 60GHz) band. The terminal may transmit and receive signals to and from the base station using the baseband processing unit 1h-20 and the RF processing unit 1h-10. Here, the signal may include control information and data.

The storage unit 1h-30 may store data such as basic programs for operation of the terminal, application programs, and setting information. The storage unit 1h-30 may provide stored data according to a request of the control unit 1h-40.

The control unit 1h-40 may control overall operations of the terminal. For example, the control unit 1h-40 may transmit and receive signals through the baseband processing unit 1h-20 and the RF processing unit 1h-10. Also, the control unit 1h-40 may write and read data in the storage unit 1h-40. To this end, the controller 1h-40 may include at least one processor. For example, the control unit 1h-40 may include a communication processor (CP) that controls communication and an application processor (AP) that controls upper layers such as application programs.

9 is a block diagram of a base station according to an embodiment of the present disclosure.

A base station according to an embodiment of the present disclosure may include one or more transmission reception points (TRPs). A base station according to an embodiment of the present disclosure includes an RF processing unit 1i-10, a baseband processing unit 1i-20, a backhaul communication unit 1i-30, a storage unit 1i-40, and a control unit 1i-50. can include

The RF processing unit 1i-10 may perform functions for transmitting and receiving signals through a wireless channel, such as band conversion and amplification of signals. That is, the RF processor 1i-10 upconverts the baseband signal provided from the baseband processor 1i-20 into an RF band signal, transmits the signal through an antenna, and converts the RF band signal received through the antenna into a baseband signal. can be downconverted to a signal. For example, the RF processor 1i-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like.

In FIG. 9, only one antenna is shown, but the base station may include multiple antennas.

Also, the RF processor 1i-10 may include a plurality of RF chains. Furthermore, the RF processor 1i-10 may perform beamforming. For beamforming, the RF processing unit 1i-10 may adjust the phase and size of signals transmitted and received through a plurality of antennas or antenna elements. The RF processor 1i-10 may perform a downlink MIMO operation by transmitting one or more layers.

The baseband processor 1i-20 may perform a conversion function between a baseband signal and a bit stream according to the physical layer standard of the first wireless access technology. For example, during data transmission, the baseband processor 1i-20 may generate complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the baseband processing unit 1i-20 may restore the received bit stream through demodulation and decoding of the baseband signal provided from the RF processing unit 1i-10. For example, when data is transmitted according to the OFDM scheme, the baseband processing unit 1i-20 generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and performs an IFFT operation and OFDM symbols may be configured through CP insertion. In addition, when receiving data, the baseband processing unit 1i-20 divides the baseband signal provided from the RF processing unit 1i-10 into OFDM symbol units, restores signals mapped to subcarriers through FFT operation, and , the received bit stream can be restored through demodulation and decoding. The baseband processing unit 1i-20 and the RF processing unit 1i-10 may transmit and receive signals as described above.

Accordingly, the baseband processing unit 1i-20 and the RF processing unit 1i-10 may be referred to as a transmission unit, a reception unit, a transmission/reception unit, a communication unit, or a wireless communication unit.

The communication unit 1i-30 may provide an interface for communicating with other nodes in the network. That is, the communication unit 1i-30 converts a bit string transmitted from the main base station to another node, for example, a secondary base station, a core network, etc. into a physical signal, and converts a physical signal received from another node into a bit string. can The base station may transmit and receive signals with the terminal using the baseband processing unit 1i-20 and the RF processing unit 1i-10. Here, the signal may include control information and data.

The storage unit 1i-40 may store data such as a basic program for operation of the main base station, an application program, and setting information. In particular, the storage unit 1i-40 may store information on bearers allocated to the connected terminal, measurement results reported from the connected terminal, and the like. In addition, the storage unit 1i-40 may store information that is a criterion for determining whether to provide or stop multiple connections to the terminal. Also, the storage unit 1i-40 may provide stored data according to a request of the control unit 1i-50. The storage unit 1i-40 may include a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD, or a combination of storage media. Also, the storage unit 1i-40 may be composed of a plurality of memories. In one embodiment, the storage unit 1i-40 may store a program for supporting beam-based cooperative communication.

The controller 1i-50 may control overall operations of the main base station. For example, the control unit 1i-50 may transmit and receive signals through the baseband processing unit 1i-20 and the RF processing unit 1i-10 or through the communication unit 1i-30. Also, the control unit 1i-50 may write and read data in the storage unit 1i-40. To this end, the control unit 1i-50 may include at least one processor.

Meanwhile, in order to achieve the high data rate considered in the present disclosure, the 5G communication system is considered to be implemented in a mmWave band (eg, a 60 gigabyte (60 GHz) band). In order to mitigate the path loss of radio waves and increase the propagation distance of radio waves in the ultra-high frequency band, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) are used in 5G communication systems. ), array antenna, analog beam-forming, and large scale antenna technologies are being discussed.

In addition, to improve the network of the system, in the 5G communication system, an evolved small cell, an advanced small cell, a cloud radio access network (cloud RAN), and an ultra-dense network , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, CoMP (Coordinated Multi-Points), unlicensed band utilization (unlicensed) and reception Technology development such as interference cancellation is being made.

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

Although the Licensed Assisted Access unlicensed system (LAA) has been studied and standardized for the unlicensed band access system supported by the licensed band, the application of the unlicensed band to the licensed band system with the main purpose of supporting the unlicensed band is more detailed. Research is needed. Scenarios that can be considered may include an unlicensed band access system through support of a licensed band, a system capable of independent operation of an unlicensed band, and the like.

This embodiment can be applied to a next-generation wireless communication system, and in a system including one or more base stations and one or more terminals and using an unlicensed band, all transmission channels for coexistence with wireless transmission technologies using other unlicensed bands It is possible to provide a system, method, and device for detecting a problem that a base station and a terminal that need to perform sensing cannot solve by themselves due to coexistence within a device effectively, and transmitting and receiving such information.

In addition, this embodiment solves the In Device Coexistence (IDC) problem that the terminal cannot solve by itself in relation to the next-generation unlicensed band (NR-Unlicensed) in a system including one or more base stations and one or more terminals. It is possible to provide a system, method, and apparatus that perform a method of reporting to the network upon discovery.

In an embodiment, a terminal may transmit any information structure (Information Element) to inform the network of its capability, and this information structure allows the terminal to solve the IDC problem related to the next-generation unlicensed band (NR-Unlicensed). It may include an indicator indicating that it is possible to determine and transmit information on the IDC problem to the network.

Since a system that performs wireless communication in an unlicensed band must inevitably share the frequency band with other unlicensed wireless communication terminals and base stations (eg, WLAN, Bluetooth, or LTE LAA terminals), Wireless transmission in unlicensed bands may require contention for occupancy of resources. Therefore, in order to prevent collisions caused by transmissions of different terminals in advance in such a competition, Listen-Before-Talk (hereinafter referred to as LBT) can be used to check channel conditions before transmission. Due to the channel occupancy of other terminals and the LBT performance of the terminal, it may not be easy to reliably succeed in transmission at the transmission time point even if a specific future transmission time point is reserved in the unlicensed band. Therefore, in order to solve this problem, it is preferable to reserve a window duration starting from a specific time point and maintaining a certain time period, and attempting transmission and reception in the window duration, rather than reserving a specific time point between the transmitting end and the receiving end. can do.

10 is a diagram for explaining a procedure for a terminal to transmit capability information to a network according to an embodiment.

In step 2a-10, the network (eg, NR base station or 5G unlicensed band (NR-Unlicensed, hereinafter NR-U) base station) requests UE in RRC_CONNECTED state to transmit UE Capability Enquiry signal can be transmitted.

In step 2a-20, the UE receiving the UECapabilityEnquiry signal may create a UECapabilityInforamtion signal including various UE capability information and transmit it to the network in step 2a-30. In an embodiment, when generating a UECapabilityInformation signal, the UE has the ability to detect IDC problems when using unlicensed band support, NR-U, or (e) LAA support, and when using these unlicensed band wireless access technologies A UECapabilityInformation signal may be generated including a message indicating that it is present. In addition, the terminal may generate the above-described UECapabilityInforamtion signal including the following messages and transmit it to the base station in order to notify that the terminal has the capability to report a problem related to the corresponding IDC to the network.

The aforementioned UECapabilityInforamtion signal may include various capability information supported by the UE. In an embodiment, a UE capable of discovering an IDC problem that may occur in a DC structure generates a UECapabilityInforamtion signal as shown in [Table 4] including a message in which inDeviceCoexInd-UL-DC is set to 'supported'. can do.

In an embodiment, inDeviceCoexInd-NRU may be set only when the UE supports NR-U, for example, when the UE includes inDeviceCoexInd in the UECapabilityInforamtion signal.

In an embodiment, the UECapabilityInforamtion signal may include various capability information supported by the UE. The terminal uses one of various radio access technologies (Radio Access Technology, hereinafter RAT) using unlicensed bands, such as NR-U, LTE (e)LAA, WLAN, Bluetooth, ZigBee, and GNSS (Global Navigation Satellite System) It can be configured to report the IDC for the above RATs, and in these multiple RATs, the UE may find an IDC problem that it cannot solve by itself. In the case of a terminal capable of discovering such an IDC problem, it may report the IDC problem related to the corresponding RAT in which the IDC problem is found to the network. In an embodiment, the terminal can inform the network that it has the capability to report the multi-RAT-related IDC problem using these unlicensed bands by transmitting a UECapabilityInforamtion signal including the following message to the network as shown in Table 6. .

In an embodiment, inDeviceCoexInd-HardwareSharingInd-NRU may be set only when the terminal supports IDC, for example, when the terminal includes inDeviceCoexInd in the UECapabilityInforamtion signal.

11 is a diagram for explaining a procedure for a terminal to transmit capability information to a network according to an embodiment. Referring to FIG. 11, a UE supporting the provision of IDC information may inform the network of UE capabilities by providing UECapabilityInforamtion to the network. You can set the provision of IDC information. The terminal configured to provide IDC information in step 2b-20 monitors whether the IDC problem set in step 2b03- occurs, and when an IDC problem occurs, generates a report signal including related information in step 2b-50, and returns to the network in step 2b-60. can report to Terminal operations related to this may be as shown in [Table 8] below.

In an embodiment, the terminal may receive an RRCConfig message (eg, otherConfig) including idc-Config, and may check whether idc-Indication is set in the received RRCConfig message. If idc-indication is set (eg, set to Setup), the terminal can recognize that it is set to provide IDC information to the network. If idc-indication-NRU is set in the RRCConfig message, the terminal can recognize that it is configured to provide NR-Unlicensed related IDC information to the network. In addition, if HardwareSharingIndication-NRU is set in the RRCConfig message, the terminal recognizes that it is configured to provide the network with hardware problem occurrence information that the terminal cannot solve by itself experiencing in the unlicensed band RAT in the terminal using the same unlicensed band as NR-U. can In an embodiment, idc-Config setting information may have a structure as shown in [Table 9] below.

In an embodiment, the terminal may monitor the IDC for each resource and connection in real time according to the set information. In addition, if an IDC problem that the terminal cannot solve by itself is observed for the corresponding resource and connection or other IDC problem information transmission conditions are satisfied, the terminal transmits information on the corresponding IDC problem to the network through an operation as shown in [Table 10] below. You can trigger and start the sending action.

Various information may be included in the IDC information signal (InDeviceCoexIndication) generated by the terminal and reported to the network, which is considered in the process of generating the IDC transmission signal of the terminal. In an embodiment, the IDC information signal may include information as shown in [Table 11] below.

In an embodiment, maxFreqIDCNRU may be a maximum unlicensed band frequency that can be affected by IDC in NR. maxFreqIDCNRU may have the same value as maxFreqIDCNR, and in this case, maxFreqIDCNR and maxFreqIDCNRU may be replaced with one constant (maxFreqIDC).

In an embodiment, the carrier frequency may allow the terminal to specify the frequency through a Measurement Object Id or an Absolute Radio-Frequency Channel Number (ARFCN) value for the NR-U serving cell and the non-serving cell.

interferenceDirection 　 can be used to indicate a victim radio system affected by interference caused by the IDC. AffectedDlNRUBWPList can indicate damaged downlink BWPs affected by interference caused by IDC. AffectedDlNRUBWPList can indicate damaged uplink BWPs affected by interference caused by IDC.

In an embodiment, Lists such as AffectedDlNRUBWPList and AffectedUlNRUBWPList may be provided in the form below such as AffectedDlNRUBWP and AffectedUlNRUBWP to set only one value, for example, as shown in [Table 12].

Meanwhile, in the IDC information signal (InDeviceCoexIndication) generated by the terminal and reported to the network, which is considered in the IDC transmission signal generation procedure of the terminal, auxiliary information affected by the NR-U related IDC as shown in [Table 13] may be included. there is.

In an embodiment, the NR-U-related auxiliary information may include combination information of carrier frequencies affected by the IDC found in the NR-U as a field named affectedCarrierFreqCombListNRU, which affects the maximum number of maxCombIDCNRUs. It may be composed of received frequency combinations (AffectedCarrierFreqCombNRU).

Also, the AffectedCarrierFreqCombNRU may include two or more pieces of uplink (UL) frequency information (AffectedCarrierFreqULNRU) of up to maxServCell or less. Here, the UL frequency information (AffectedCarrierFreqULNRU) may include a carrier frequency, a SUL indicator, and AffectedUlNRUBWPList.

In an embodiment, the UL CA-related auxiliary information includes victimSystemType that suffers damage due to the IDC found in the corresponding UL CA, which may be shown in [Table 15].

The terminal may transmit an IDC information signal (InDeviceCoexIndication) to the network. In an embodiment, a procedure for generating an IDC information signal by a terminal may be as shown in [Table 16] below.

12 is a diagram for explaining a procedure for a terminal to transmit capability information to a network according to an embodiment. Referring to FIG. 12, a UE may be connected to an NR primary cell using a licensed band and communicate with an NR gNB. A UE connected to an NR primary cell can simultaneously connect to an NR-U secondary cell, and a UE having such capabilities may have capabilities related to NR-U and capabilities to detect NR-U IDC problems.

In step 2c-10, the UE may inform the gNB of the UE capability by providing UECapabilityInforamtion to the NR primary cell gNB using the licensed band. It can be transmitted to the licensed band to set the provision of IDC information related to the NR-U secondary cell to the UE.

In step 2c-30, the terminal configured to provide IDC information may monitor whether a set IDC problem occurs in the NR-U secondary cell and unlicensed band. When an IDC problem that cannot be resolved by itself occurs, in step 2c-40, a report signal including related information may be generated and reported to the NR primary cell gNB through the licensed band.

In step 2c-50, the gNB receiving the IDC problem report sends a message including a method for solving the IDC problem related to the NR-U secondary cell to the UE, for example, a changed configuration of the NR-U secondary cell, etc. It is possible to solve the above-described IDC problem by transmitting through.

Of course, the primary cell of the above-described licensed band may be an E-UTRA LTE cell as well as an NR cell, and the gNB may also be an eNB.

13 is a block diagram illustrating the structure of a terminal according to an embodiment. Referring to FIG. 13 , a terminal may include a transceiver 2d-20, a memory 2d-30, and a processor 2d-10. According to the communication method of the terminal described above, the transceiver 2d-20, the memory 2d-30, and the processor 2d-10 of the terminal may operate. However, the components of the terminal are not limited to the above-described examples. For example, a terminal may include more or fewer components than the aforementioned components. In addition, the transceiver 2d-20, the memory 2d-30, and the processor 2d-10 may be implemented as a single chip.

The transmitting and receiving unit 2d-20 may transmit and receive signals to and from the base station. Here, the signal may include control information and data. To this end, the transceiver 2d-20 may include an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that amplifies a received signal with low noise and down-converts its frequency. However, this is only one embodiment of the transceiver 2d-20, and components of the transceiver 2d-20 are not limited to the RF transmitter and the RF receiver.

Also, the transceiver 2d-20 may receive a signal through a radio channel, output the signal to the processor 2d-10, and transmit the signal output from the processor 2d-10 through a radio channel.

The memory 2d-30 may store programs and data required for operation of the terminal. Also, the memory 2d-30 may store control information or data included in a signal obtained from the terminal. The memory 2d-30 may be composed of a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

The processor 2d-10 may control a series of processes so that the terminal can operate according to the above-described embodiment. According to some embodiments, the processor 2d-10 performs synchronization signal transmission period and synchronization based on information included in a synchronization signal block (SSB) received from the base station through the transceiver 2d-20. Components of the terminal may be controlled to perform synchronization by determining a signal offset and a window duration of a synchronization signal bundle.

In addition, the processor 2d-10 provides DC (Dual Connectivity), BWP (Bandwidth Part), and SUL (Supplementary Uplink) related IDC reporting information included in the idc-Config message included in the RRCConfiguration signal received from the base station. Based on this, it is determined whether an IDC problem has occurred, and if it is determined that an IDC problem has occurred, it is possible to control components of the terminal to generate and transmit a report signal including information on the occurred IDC problem to the base station.

14 is a block diagram showing the structure of a base station according to an embodiment. Referring to FIG. 14, a base station may include a transceiver 2e-20, a memory 2e-30, and a processor 2e-10. According to the communication method of the base station described above, the transceiver 2e-20, the memory 2e-30, and the processor 2e-10 of the base station may operate. However, components of the base station are not limited to the above-described examples. For example, a base station may include more or fewer components than those described above. In addition, the transceiver 2e-20, the memory 2e-30, and the processor 2e-10 may be implemented as a single chip.

The transmitting and receiving unit 2e-20 may transmit and receive signals to and from the terminal. Here, the signal may include control information and data. To this end, the transceiver 2e-20 may include an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that amplifies a received signal with low noise and down-converts its frequency. However, this is only one embodiment of the transceiver 2e-20, and components of the transceiver 2e-20 are not limited to the RF transmitter and the RF receiver.

In addition, the transceiver 2e-20 may receive a signal through a radio channel, output the signal to the processor 2e-10, and transmit the signal output from the processor 2e-10 through a radio channel.

The memory 2e-30 may store programs and data necessary for the operation of the base station. Also, the memory 2e-30 may store control information or data included in a signal obtained from the base station. The memory 2e-30 may be composed of a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

The processor 2e-10 may control a series of processes so that the base station operates according to the above-described embodiment of the present disclosure. According to some embodiments, the processor 2e-10 sets an SSB Burst Length having a specific time length in relation to transmission of a Synchronization Signal Block (SSB), and divides the SSB Burst Length into a plurality of intervals as a unit. Set the configured window duration, set the timing to transmit the synchronization signal bundle within a plurality of intervals, perform LBT (Listen-Before-Talk), and when LBT is successful, the LBT successful timing and details Each component of the base station may be controlled to transmit the synchronization signal bundle to the terminal based on the timing of transmitting the synchronization signal bundle set within the plurality of sections.

In addition, the processor 2e-10 may control each component of the base station to transmit the RRCConfiguration signal including the idc-Config message to the terminal.

Methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

When implemented in software, a computer readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in a computer-readable storage medium are configured for execution by one or more processors in an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to embodiments described in the claims or specification of the present disclosure.

Such programs (software modules, software) may include random access memory, non-volatile memory including flash memory, read only memory (ROM), and electrically erasable programmable ROM. (EEPROM: Electrically Erasable Programmable Read Only Memory), magnetic disc storage device, Compact Disc-ROM (CD-ROM), Digital Versatile Discs (DVDs), or other forms of It can be stored on optical storage devices, magnetic cassettes. Alternatively, it may be stored in a memory composed of a combination of some or all of these. In addition, each configuration memory may be included in multiple numbers.

In addition, the above-described program is a communication network such as the Internet, an intranet, a local area network (LAN), a wide LAN (WLAN), or a storage area network (SAN), or a communication network composed of a combination thereof. It can be stored in an attachable storage device that can be accessed through. Such a storage device may be connected to a device performing an embodiment of the present disclosure through an external port. In addition, a separate storage device on a communication network may be connected to a device performing an embodiment of the present disclosure.

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 understanding of the present disclosure, and are not intended to limit the scope of the present disclosure. That is, it is obvious to those skilled in the art that other modified examples based on the technical idea of the present disclosure can be implemented. In addition, each of the above-described embodiments can be operated in combination with each other as needed. For example, parts of each embodiment of the present disclosure (eg, Embodiment 1, Embodiment 2, and Embodiment 3) may be combined with each other to operate the base station and the terminal. In addition, although the above examples have been presented based on the NR system, other modified examples based on the technical idea of the embodiment may be implemented in other systems such as FDD or TDD LTE systems.

In addition, the present specification and drawings disclose preferred embodiments of the present disclosure, and although specific terms are used, they are only used in a general sense to easily describe the technical content of the present disclosure and help understanding of the present invention. It is not intended to limit the scope of the disclosure. In addition to the embodiments disclosed herein, it is obvious to those skilled in the art that other modified examples based on the technical spirit of the present disclosure may be implemented.

Claims (15)

A method for performing random access by a terminal in a wireless communication system,
Acquiring PRACH (Physical Random Access Channel) resource allocation information for random access;
Transmitting a random access preamble based on the PRACH resource allocation information;
Receiving a Random Access Response (RAR) based on the transmitted random access preamble; and
Transmitting an RRC layer message Msg3 a plurality of times based on uplink resource allocation information included in the received RAR;
The terminal is in RRC (Radio Resource Control) idle mode or RRC inactive mode,
The PRACH resource allocation information,
Among PRACH slots, resource information for transmitting the random access preamble in a PRACH Occasion corresponding to a resource allocated to transmit the Msg3 multiple times is included,
The PRACH Occasion,
Corresponding to a resource allocated to transmit the Msg3 multiple times in a PRACH slot.

According to claim 1,
The method,
The method further comprising receiving at least one Synchronization Signal Block (SSB).

delete According to claim 2,
The PRACH resource allocation information,
And including resource information for transmitting the random access preamble in a PRACH Occasion indicated by an SSB having a signal strength greater than or equal to a predetermined threshold among the received SSBs.
According to claim 1,
The RAR is,
Includes modulation and coding scheme (MCS) information;
In the step of transmitting the Msg3 multiple times,
Further comprising performing modulation and coding on the Msg3 based on the MCS information;
Transmitting the modulated and coded Msg3 a plurality of times based on the uplink resource allocation information.
A method for allocating resources for random access by a base station,
Transmitting PRACH (Physical Random Access Channel) resource allocation information for random access;
receiving a random access preamble based on the PRACH resource allocation information;
Transmitting a Random Access Response (RAR) based on the received random access preamble; and
Receiving an RRC layer message Msg3 a plurality of times based on uplink resource allocation information included in the transmitted RAR;
The PRACH resource allocation information,
and resource information for receiving the random access preamble in a PRACH Occasion corresponding to a resource allocated to transmit the Msg3 multiple times among PRACH slots.
delete In a terminal performing random access,
transceiver; and
At least one or more processors connected to the transceiver; includes,
The at least one or more processors,
Obtaining physical random access channel (PRACH) resource allocation information for random access;
Transmitting a random access preamble based on the PRACH resource allocation information;
Receiving a Random Access Response (RAR) based on the transmitted random access preamble;
Transmitting Msg3 multiple times based on uplink resource allocation information included in the received RAR;
The PRACH resource allocation information,
Among PRACH slots, resource information for transmitting the random access preamble in a PRACH Occasion corresponding to a resource allocated to transmit the Msg3 multiple times is included,
The PRACH Occasion,
Corresponding to a resource allocated to transmit the Msg3 multiple times in the PRACH slot, the terminal.
According to claim 8,
The at least one or more processors,
A terminal that receives a Synchronization Signal Block (SSB).

delete According to claim 9,
The PRACH resource allocation information,
and resource information for transmitting the random access preamble in a PRACH Occasion indicated by an SSB having a signal strength greater than or equal to a predetermined threshold among the received SSBs.
According to claim 8,
The RAR is,
Includes modulation and coding scheme (MCS) information;
The at least one or more processors,
performing modulation and coding on the Msg3 based on the MCS information;
Transmitting the modulated and coded Msg3 multiple times based on the uplink resource allocation information.
In a base station that allocates resources for random access,
transceiver; and
At least one or more processors connected to the transceiver; includes,
The at least one or more processors,
Transmits PRACH (Physical Random Access Channel) resource allocation information for random access,
Receiving a random access preamble based on the PRACH resource allocation information;
Transmitting a Random Access Response (RAR) based on the received random access preamble;
Receiving Msg3 multiple times based on uplink resource allocation information included in the transmitted RAR;
The PRACH resource allocation information,
and resource information for receiving the random access preamble in a PRACH Occasion corresponding to a resource allocated to transmit the Msg3 multiple times among PRACH slots.
delete A computer-readable recording medium on which a program for executing the method of claim 1 is recorded on a computer.

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