WO2024248176A1 - Method and device for retransmission in wireless communication system - Google Patents

Abstract

A method performed by a user equipment (UE) in a wireless communication system according to an embodiment of the present disclosure may comprise the steps of: receiving one or more synchronization signals from a base station (BS); receiving control information from the BS; receiving first downlink control information (DCI) including first information from the BS through a first channel; receiving a first code block (CB) from the BS through a second channel; determining, on the basis of the first information, whether the first CB is initially transmitted from the BS; and on the basis of whether the first CB is initially transmitted, transmitting a first hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback to the BS.

Description

Method and device for retransmission in wireless communication system

The present disclosure relates to a wireless communication system. Specifically, the present disclosure relates to a retransmission method and device in a wireless communication system.

Wireless access systems are being widely deployed to provide various types of communication services such as voice and data. In general, wireless access systems are multiple access systems that can support communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of multiple access systems include CDMA (code division multiple access) systems, FDMA (frequency division multiple access) systems, TDMA (time division multiple access) systems, OFDMA (orthogonal frequency division multiple access) systems, and SC-FDMA (single carrier frequency division multiple access) systems.

In particular, as many communication devices require large communication capacity, enhanced mobile broadband (eMBB) communication technology is being proposed compared to the existing radio access technology (RAT). In addition, a communication system that considers reliability and latency-sensitive services/UE (user equipment) as well as mMTC (massive machine type communications) that connects a large number of devices and objects to provide various services anytime and anywhere is being proposed. Various technology configurations are being proposed for this.

In order to solve the above-described problem, the technical problem of the present disclosure is to provide a retransmission method and device in a wireless communication system in which one device (e.g., a base station or an AP (Access point)) transmits the same data to a plurality of devices (e.g., terminals).

The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

In another embodiment of the present disclosure, a method performed by a user equipment (UE) in a wireless communication system may include the steps of receiving one or more synchronization signals from a base station (BS), receiving control information from the base station, receiving a first DCI (downlink control information) including first information from the base station through a first channel, receiving a first CB (Code block) from the base station through a second channel, determining whether the first CB is initially transmitted from the base station based on the first information, and transmitting a first HARQ-ACK (Hybrid Automatic Repeat reQuest Acknowledgement) feedback to the base station based on whether the first CB is initially transmitted.

The step of transmitting a first HARQ-ACK feedback to the base station based on whether the first CB is initially transmitted from the base station may further include the steps of: storing a first PCB included in the first CB if it is determined that the first CB is not initially transmitted; generating a first HARQ-ACK feedback requesting retransmission of the initially transmitted second CB; transmitting the first HARQ-ACK feedback to the base station; receiving, from the base station through the first channel, a second DCI including the first information and information about a size of the second CB; and receiving, from the base station through the second channel, a second CB including a plurality of DCBs (data code blocks) and a second PCB.

The method may further include a step of determining whether there are DCBs in which errors have occurred among a plurality of DCBs included in the second CB, a step of determining the number of the first PCBs, a step of determining the number of third PCBs for recovering the DCBs in which errors have occurred based on the number of PCBs in which errors have not occurred among the first PCBs and the second PCBs if there are DCBs in which errors have occurred among the plurality of DCBs, a step of generating second HARQ-ACK feedback based on the number of third PCBs and the preset table, a step of transmitting the second HARQ-ACK feedback to the base station, and a step of receiving a fourth PCB greater than or equal to the number of the third PCBs from the base station.

The step of determining the number of the first PCBs includes a step of determining the number of the first PCBs based on at least one of information regarding the size of the second CB included in the second DCI, information regarding the length of a CRC (Cyclic Redundancy Check) of the second CB, or information regarding the number of coded bits included in the first DCI, and the number of coded bits may be determined based on at least one of information regarding the number of wireless resources included in the first DCI, information regarding a modulation order, information regarding a code rate, or information regarding the number of layers.

The step of transmitting the first HARQ-ACK feedback to the base station based on whether the first CB is transmitted initially comprises: a step of determining whether there are DCBs in which errors occur among the plurality of DCBs included in the first CB if it is determined that the first CB is transmitted initially; a step of obtaining the number of fifth PCBs for recovering the DCBs in which errors occur based on the number of first PCBs in which errors do not occur among the first PCBs included in the first CB if there are DCBs in which errors occur among the plurality of DCBs; a step of generating the first HARQ-ACK feedback based on the number of fifth PCBs; a step of transmitting the first HARQ-ACK feedback to the base station; a step of receiving, from the base station, through the first channel, a third DCI including at least one of information regarding the number of wireless resources of the first information and the second channel, information regarding a modulation order, information regarding a code rate, or information regarding the number of layers; and a step of receiving, from the base station, through the second channel, a sixth PCB equal to or greater than the number of the fifth PCBs. It can include more.

The step of generating the first HARQ-ACK feedback based on the number of the fifth PCBs includes the step of receiving, from the base station, a first table including information regarding the number of the fifth PCBs, information regarding the number of bits of the first HARQ-ACK feedback, and information regarding the number of the sixth PCBs, or information necessary to generate the first table; and the step of generating the first HARQ-ACK feedback based on the number of the fifth PCBs and the first table, wherein the information regarding the number of the fifth PCBs and the information regarding the number of the sixth PCBs included in the first table can be determined based on the number of the plurality of DCBs included in the first CB and a probability distribution of the fifth PCB according to the number of the plurality of DCBs.

The number of the sixth PCB is determined based on at least one of information regarding the size of the first CB included in the first DCI, information regarding the length of a CRC (Cyclic Redundancy Check) of the first CB, or information regarding the number of coded bits included in the third DCI, and the number of coded bits can be determined based on at least one of information regarding the number of wireless resources included in the third DCI, information regarding a modulation order, information regarding a code rate, or information regarding the number of layers.

The index of the sixth PCB may be determined based on a second table including information about the number of the first PCB, the number of the sixth PCB, and the number of the fifth PCB, information about the number of bits of the first HARQ-ACK feedback, information about the number of the sixth PCB, and information about the start index of the sixth PCB.

In a communication system according to one embodiment of the present disclosure, a user equipment (UE) includes one or more transceivers, one or more processors controlling the one or more transceivers, and a memory including one or more instructions to be executed by the one or more processors, wherein the one or more instructions may include the steps of: receiving one or more synchronization signals from a base station (BS); receiving control information from the BS; receiving a first DCI (downlink control information) including first information from the BS through a first channel; receiving a first CB (Code block) from the BS through a second channel; determining whether the first CB is initially transmitted from the BS based on the first information; and transmitting a first HARQ-ACK (Hybrid Automatic Repeat reQuest Acknowledgement) feedback to the BS based on whether the first CB is initially transmitted.

A method performed by a base station (BS) in a wireless communication system according to one embodiment of the present disclosure may include the steps of transmitting one or more synchronization signals to a user equipment (UE), transmitting control information to the UE, transmitting downlink control information (DCI) to the UE through a first channel, transmitting a first CB (Code block) to the UE through a second channel, receiving a HARQ-ACK (Hybrid Automatic Repeat reQuest Acknowledgement) feedback from the UE, and retransmitting a second CB initially transmitted to the UE or transmitting an additional PCB based on the HARQ-ACK feedback.

The step of retransmitting, to the terminal, the second CB initially transmitted to the terminal based on the HARQ-ACK feedback or transmitting an additional PCB may include the step of retransmitting, to the terminal, the second CB through a redundancy version (Redundancy Version, RV) different from a redundancy version of the initial transmission, if the HARQ-ACK feedback includes information regarding a request for retransmission of the second CB.

The step of retransmitting, to the terminal, the second CB initially transmitted to the terminal based on the HARQ-ACK feedback, or transmitting an additional PCB may include the step of transmitting, to the terminal, an additional PCB greater than the number of PCBs requested for transmission, if the HARQ-ACK feedback includes information regarding an additional PCB transmission request.

The number of the additional PCBs is determined based on a first table including information about the number of the requested transmission PCBs, information about the number of bits of the HARQ-ACK feedback, and information about the number of the additional PCBs, and the information about the number of the requested transmission PCBs and the information about the number of the additional PCBs included in the first table can be determined based on the number of the plurality of DCBs included in the first CB and a probability distribution of the additional PCBs according to the number of the plurality of DCBs.

The index of the additional PCB may be determined based on a second table including information about the number of PCBs included in the first CB, the number of the additional PCBs, and the number of PCBs requested for transmission, information about the number of bits of the HARQ-ACK feedback, information about the number of the additional PCBs, and information about the start index of the additional PCB.

In a communication system according to one embodiment of the present disclosure, a base station (BS) includes one or more transceivers, one or more processors controlling the one or more transceivers, and a memory including one or more instructions to be executed by the one or more processors, wherein the one or more instructions may include: transmitting one or more synchronization signals to a user equipment (UE); transmitting control information to the UE; transmitting downlink control information (DCI) to the UE through a first channel; transmitting a first CB (Code block) to the UE through a second channel; receiving a HARQ-ACK (Hybrid Automatic Repeat reQuest Acknowledgement) feedback from the UE; and retransmitting, to the UE, a second CB initially transmitted to the UE based on the HARQ-ACK feedback, or transmitting a first PCB.

In an embodiment of the present disclosure, a device including one or more memories and one or more processors functionally connected with the one or more memories, wherein the one or more processors are operable to cause the device to receive at least one synchronization signal from a base station (BS), receive control information from the BS, receive a first DCI (downlink control information) including first information from the BS through a first channel, receive a first CB (Code block) from the BS through a second channel, determine whether the first CB is initially transmitted from the BS based on the first information, and transmit a first HARQ-ACK (Hybrid Automatic Repeat reQuest Acknowledgement) feedback to the BS based on whether the first CB is initially transmitted.

One or more non-transitory computer-readable media storing one or more commands according to one embodiment of the present disclosure, the instructions being operable to: receive at least one synchronization signal from a base station (BS); receive control information from the BS; receive a first DCI (downlink control information) including first information from the BS through a first channel; receive a first CB (Code block) from the BS through a second channel; determine whether the first CB is initially transmitted from the BS based on the first information; and transmit a first HARQ-ACK (Hybrid Automatic Repeat reQuest Acknowledgement) feedback to the BS based on whether the first CB is initially transmitted.

According to the present disclosure, when one base station transmits the same data to multiple terminals through the same radio resource, transmission reliability can be increased and transmission delay can be reduced by using an erasure code.

Additionally, according to the present disclosure, when retransmission is required, the base station can recover errors from multiple terminals with a small amount of radio resources.

The drawings attached below are intended to aid understanding of the present specification and may provide embodiments of the present specification together with detailed descriptions. However, the technical features of the present specification are not limited to specific drawings, and the features disclosed in each drawing may be combined with each other to form new embodiments. Reference numerals in each drawing may mean structural elements.

Figure 1 is a drawing showing an example of a communication system applicable to this specification.

FIG. 2 is a drawing showing an example of a wireless device applicable to this specification.

FIG. 3 is a diagram illustrating a method for processing a transmission signal applicable to the present specification.

FIG. 4 is a drawing showing another example of a wireless device applicable to this specification.

FIG. 5 is a drawing showing an example of a portable device applicable to this specification.

Figure 6 is a diagram showing physical channels applicable to this specification and a signal transmission method using them.

Figure 7 is a diagram showing the structure of a wireless frame applicable to this specification.

Figure 8 is a drawing showing a slot structure applicable to this specification.

FIG. 9 is a diagram showing an example of a communication structure that can be provided in a 6G system applicable to this specification.

Figure 10 shows an example of a perceptron structure.

Figure 11 shows an example of a multilayer perceptron structure.

Figure 12 shows an example of a deep neural network.

Figure 13 shows an example of a convolutional neural network.

Figure 14 is a diagram showing an example of a filter operation in a convolutional neural network.

Figure 15 shows an example of a neural network structure in which a recurrent loop exists.

Figure 16 shows an example of the operational structure of a recurrent neural network.

Figure 17 is a diagram showing an electromagnetic spectrum applicable to this specification.

Fig. 18 is a diagram showing a THz communication method applicable to this specification.

FIG. 19 is a diagram illustrating a THz wireless communication transceiver applicable to the present specification.

FIG. 20 is a diagram illustrating a THz signal generation method applicable to the present specification.

FIG. 21 is a diagram illustrating a wireless communication transceiver applicable to this specification.

Figure 22 is a drawing showing a transmitter structure applicable to this specification.

Figure 23 is a drawing showing a modulator structure applicable to this specification.

FIG. 24 is a diagram illustrating an example of a communication system according to one embodiment of the present disclosure.

FIG. 25 is a diagram illustrating an example of a data transmission method according to one embodiment of the present disclosure.

FIG. 26 is a diagram illustrating an example of a CB transmission method according to one embodiment of the present disclosure.

FIG. 27 is a diagram illustrating an example of a minimum number of PCBs according to the number of DCBs required for a TB group BLER to be less than or equal to a preset value according to one embodiment of the present disclosure.

FIG. 28 is a flowchart of a method for obtaining the number of DCBs according to one embodiment of the present disclosure.

FIG. 29 is a diagram illustrating an example of a retransmission method according to one embodiment of the present disclosure.

FIG. 30 is a diagram illustrating an example of a retransmission method according to another embodiment of the present disclosure.

FIG. 31 is a flowchart of a signal transmission and reception method according to one embodiment of the present disclosure.

FIG. 32 is a flowchart of a signal transmission and reception method according to another embodiment of the present disclosure.

The following embodiments combine the components and features of the present specification in a predetermined form. Each component or feature may be considered optional unless otherwise explicitly stated. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, some components and/or features may be combined to form an embodiment of the present specification. The order of operations described in the embodiments of the present specification may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment.

In the description of the drawings, procedures or steps that may obscure the gist of the present specification are not described, and procedures or steps that can be understood by those skilled in the art are also not described.

Throughout the specification, when a part is said to "comprising" (or including) a certain component, this does not mean that other components are excluded, but rather that other components can be included, unless otherwise specifically stated. In addition, terms such as "part," "unit," "module," etc. described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware, software, or a combination of hardware and software. In addition, "a" or "an," "one," "the," and similar related words may be used in the context of describing this specification (especially in the context of the claims below) to include both the singular and the plural, unless otherwise indicated herein or clearly contradicted by the context.

The embodiments of this specification have been described with a focus on the data transmission and reception relationship between a base station and a mobile station. Here, the base station is meant as a terminal node of a network that directly communicates with a mobile station. A specific operation described as being performed by the base station in this specification may in some cases be performed by an upper node of the base station.

That is, in a network consisting of a plurality of network nodes including a base station, various operations performed for communication with a mobile station may be performed by the base station or other network nodes other than the base station. In this case, the 'base station' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), a gNode B (gNB), an ng-eNB, an advanced base station (ABS), or an access point.

Additionally, in the embodiments of the present specification, the term terminal may be replaced with terms such as user equipment (UE), mobile station (MS), subscriber station (SS), mobile subscriber station (MSS), mobile terminal, or advanced mobile station (AMS).

In addition, the transmitter refers to a fixed and/or mobile node that provides data service or voice service, and the receiver refers to a fixed and/or mobile node that receives data service or voice service. Accordingly, in the case of uplink, a mobile station can be a transmitter and a base station can be a receiver. Similarly, in the case of downlink, a mobile station can be a receiver and a base station can be a transmitter.

Embodiments of the present specification may be supported by standard documents disclosed in at least one of wireless access systems, namely IEEE 802.xx system, 3rd Generation Partnership Project (3GPP) system, 3GPP Long Term Evolution (LTE) system, 3GPP 5G (5th generation) NR (New Radio) system and 3GPP2 system, and in particular, embodiments of the present specification may be supported by 3GPP TS (technical specification) 38.211, 3GPP TS 38.212, 3GPP TS 38.213, 3GPP TS 38.321 and 3GPP TS 38.331 documents.

In addition, the embodiments of the present specification may be applied to other wireless access systems and are not limited to the above-described system. For example, they may be applied to systems applied after the 3GPP 5G NR system and are not limited to a specific system.

That is, obvious steps or parts that are not described in the embodiments of this specification can be described by referring to the above documents. In addition, all terms disclosed in this specification can be described by the above standard documents.

Hereinafter, preferred embodiments according to the present specification will be described in detail with reference to the accompanying drawings. The detailed description set forth below together with the accompanying drawings is intended to explain exemplary embodiments of the present specification and is not intended to represent the only embodiments in which the technical configuration of the present specification may be implemented.

In addition, specific terms used in the embodiments of this specification are provided to help understanding of this specification, and the use of such specific terms may be changed to other forms without departing from the technical spirit of this specification.

The following technology can be applied to various wireless access systems such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), and SC-FDMA (single carrier frequency division multiple access).

In the following, for the purpose of clarity, the description is based on a 3GPP communication system (e.g., LTE, NR, etc.), but the technical spirit of the present invention is not limited thereto. LTE may refer to technology after 3GPP TS 36.xxx Release 8. Specifically, LTE technology after 3GPP TS 36.xxx Release 10 may be referred to as LTE-A, and LTE technology after 3GPP TS 36.xxx Release 13 may be referred to as LTE-A pro. 3GPP NR may refer to technology after TS 38.xxx Release 15. 3GPP 6G may refer to technology after TS Release 17 and/or Release 18. “xxx” refers to a standard document detail number. LTE/NR/6G may be collectively referred to as a 3GPP system.

For background information, terms, abbreviations, etc. used in this specification, reference may be made to standard documents published prior to the invention of the present invention. For example, reference may be made to standard documents 36.xxx and 38.xxx.

Communication systems applicable to this specification

Although not limited thereto, the various descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed herein may be applied to various fields requiring wireless communication/connectivity (e.g., 5G) between devices.

Hereinafter, more specific examples will be provided with reference to the drawings. In the drawings/descriptions below, the same drawing symbols may illustrate identical or corresponding hardware blocks, software blocks, or functional blocks, unless otherwise described.

FIG. 1 is a diagram illustrating an example of a communication system applied to the present specification. Referring to FIG. 1, a communication system (100) applied to the present specification includes a wireless device, a base station, and a network. Here, the wireless device means a device that performs communication using a wireless access technology (e.g., 5G NR, LTE) and may be referred to as a communication/wireless/5G device. Although not limited thereto, the wireless device may include a robot (100a), a vehicle (100b-1, 100b-2), an XR (extended reality) device (100c), a hand-held device (100d), a home appliance (100e), an IoT (Internet of Thing) device (100f), and an AI (artificial intelligence) device/server (100g). For example, the vehicle may include a vehicle equipped with a wireless communication function, an autonomous vehicle, a vehicle capable of performing vehicle-to-vehicle communication, etc. Here, the vehicles (100b-1, 100b-2) may include unmanned aerial vehicles (UAVs) (e.g., drones). The XR devices (100c) include augmented reality (AR)/virtual reality (VR)/mixed reality (MR) devices, and may be implemented in the form of a head-mounted device (HMD), a head-up display (HUD) equipped in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance, digital signage, a vehicle, a robot, etc. The portable devices (100d) may include a smartphone, a smart pad, a wearable device (e.g., a smart watch, smart glasses), a computer (e.g., a laptop, etc.), etc. The home appliances (100e) may include a TV, a refrigerator, a washing machine, etc. The IoT devices (100f) may include sensors, smart meters, etc. For example, the base station (120) and network (130) may also be implemented as wireless devices, and a specific wireless device (120a) may act as a base station/network node to other wireless devices.

Wireless devices (100a to 100f) can be connected to a network (130) via a base station (120). AI technology can be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (100g) via a network (130). The network (130) can be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, etc. The wireless devices (100a to 100f) can communicate with each other via the base station (120)/network (130), but can also communicate directly (e.g., sidelink communication) without going through the base station (120)/network (130). For example, vehicles (100b-1, 100b-2) can communicate directly (e.g., V2V (vehicle to vehicle)/V2X (vehicle to everything) communication). Additionally, an IoT device (100f) (e.g., a sensor) can communicate directly with another IoT device (e.g., a sensor) or another wireless device (100a to 100f).

Wireless communication/connection (150a, 150b, 150c) can be established between wireless devices (100a to 100f)/base stations (120), and base stations (120)/base stations (120). Here, the wireless communication/connection can be established through various wireless access technologies (e.g., 5G NR) such as uplink/downlink communication (150a), sidelink communication (150b) (or, D2D communication), and communication between base stations (150c) (e.g., relay, IAB (integrated access backhaul)). Through the wireless communication/connection (150a, 150b, 150c), the wireless device and base station/wireless device, and the base station and base station can transmit/receive wireless signals to each other. For example, the wireless communication/connection (150a, 150b, 150c) can transmit/receive signals through various physical channels. To this end, at least some of the various configuration information setting processes for transmitting/receiving wireless signals, various signal processing processes (e.g., channel encoding/decoding, modulation/demodulation, resource mapping/demapping, etc.), and resource allocation processes may be performed based on various proposals of this specification.

Communication systems applicable to this specification

FIG. 2 is a drawing illustrating an example of a wireless device to which the present specification can be applied.

Referring to FIG. 2, the first wireless device (200a) and the second wireless device (200b) can transmit and receive wireless signals through various wireless access technologies (e.g., LTE, NR). Here, {the first wireless device (200a), the second wireless device (200b)} can correspond to {the wireless device (100x), the base station (120)} and/or {the wireless device (100x), the wireless device (100x)} of FIG. 1.

A first wireless device (200a) includes one or more processors (202a) and one or more memories (204a), and may additionally include one or more transceivers (206a) and/or one or more antennas (208a). The processor (202a) controls the memory (204a) and/or the transceiver (206a), and may be configured to implement the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed herein. For example, the processor (202a) may process information in the memory (204a) to generate first information/signal, and then transmit a wireless signal including the first information/signal via the transceiver (206a). In addition, the processor (202a) may receive a wireless signal including second information/signal via the transceiver (206a), and then store information obtained from signal processing of the second information/signal in the memory (204a). The memory (204a) may be connected to the processor (202a) and may store various information related to the operation of the processor (202a). For example, the memory (204a) may perform some or all of the processes controlled by the processor (202a), or may store software codes including instructions for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed herein. Here, the processor (202a) and the memory (204a) may be part of a communication modem/circuit/chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (206a) may be connected to the processor (202a) and may transmit and/or receive wireless signals via one or more antennas (208a). The transceiver (206a) may include a transmitter and/or a receiver. The transceiver (206a) may be used interchangeably with an RF (radio frequency) unit. In this specification, wireless device may also mean a communication modem/circuit/chip.

The second wireless device (200b) includes one or more processors (202b), one or more memories (204b), and may additionally include one or more transceivers (206b) and/or one or more antennas (208b). The processor (202b) may control the memory (204b) and/or the transceiver (206b), and may be configured to implement the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed herein. For example, the processor (202b) may process information in the memory (204b) to generate third information/signal, and then transmit a wireless signal including the third information/signal via the transceiver (206b). In addition, the processor (202b) may receive a wireless signal including fourth information/signal via the transceiver (206b), and then store information obtained from signal processing of the fourth information/signal in the memory (204b). The memory (204b) may be connected to the processor (202b) and may store various information related to the operation of the processor (202b). For example, the memory (204b) may perform some or all of the processes controlled by the processor (202b), or may store software codes including instructions for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed herein. Here, the processor (202b) and the memory (204b) may be part of a communication modem/circuit/chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (206b) may be connected to the processor (202b) and may transmit and/or receive wireless signals via one or more antennas (208b). The transceiver (206b) may include a transmitter and/or a receiver. The transceiver (206b) may be used interchangeably with an RF unit. In this specification, wireless device may also mean a communication modem/circuit/chip.

Hereinafter, hardware elements of the wireless device (200a, 200b) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (202a, 202b). For example, one or more processors (202a, 202b) may implement one or more layers (e.g., functional layers such as physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), radio resource control (RRC), service data adaptation protocol (SDAP)). One or more processors (202a, 202b) may generate one or more Protocol Data Units (PDUs) and/or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed herein. One or more processors (202a, 202b) may generate messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and/or operational flowcharts disclosed herein. One or more processors (202a, 202b) may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, functions, procedures, proposals and/or methods disclosed herein and provide the signals to one or more transceivers (206a, 206b). One or more processors (202a, 202b) may receive signals (e.g., baseband signals) from one or more transceivers (206a, 206b) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and/or operational flowcharts disclosed herein.

The one or more processors (202a, 202b) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. The one or more processors (202a, 202b) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more application specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), or one or more field programmable gate arrays (FPGAs) may be included in the one or more processors (202a, 202b). The descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed herein may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. The descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in this specification may be implemented using firmware or software configured to perform one or more of the processors (202a, 202b), or may be stored in one or more memories (204a, 204b) and executed by one or more of the processors (202a, 202b). The descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in this specification may be implemented using firmware or software in the form of codes, instructions and/or sets of instructions.

One or more memories (204a, 204b) may be coupled to one or more processors (202a, 202b) and may store various forms of data, signals, messages, information, programs, codes, instructions, and/or commands. The one or more memories (204a, 204b) may be comprised of read only memory (ROM), random access memory (RAM), erasable programmable read only memory (EPROM), flash memory, hard drives, registers, cache memory, computer readable storage media, and/or combinations thereof. The one or more memories (204a, 204b) may be located internally and/or externally to the one or more processors (202a, 202b). Additionally, the one or more memories (204a, 204b) may be coupled to the one or more processors (202a, 202b) via various technologies, such as wired or wireless connections.

One or more transceivers (206a, 206b) can transmit user data, control information, wireless signals/channels, etc., as described in the methods and/or flowcharts of this specification, to one or more other devices. One or more transceivers (206a, 206b) can receive user data, control information, wireless signals/channels, etc., as described in the descriptions, functions, procedures, suggestions, methods and/or flowcharts of this specification, from one or more other devices. For example, one or more transceivers (206a, 206b) can be coupled to one or more processors (202a, 202b) and can transmit and receive wireless signals. For example, one or more processors (202a, 202b) can control one or more transceivers (206a, 206b) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (202a, 202b) may control one or more transceivers (206a, 206b) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (206a, 206b) may be coupled to one or more antennas (208a, 208b), and one or more transceivers (206a, 206b) may be configured to transmit and receive user data, control information, wireless signals/channels, and the like, as referred to in the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed herein, via one or more antennas (208a, 208b). In the present specification, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (206a, 206b) may convert received user data, control information, wireless signals/channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals/channels, etc. using one or more processors (202a, 202b). One or more transceivers (206a, 206b) may convert processed user data, control information, wireless signals/channels, etc. from baseband signals to RF band signals using one or more processors (202a, 202b). For this purpose, one or more transceivers (206a, 206b) may include an (analog) oscillator and/or filter.

FIG. 3 is a diagram illustrating a method for processing a transmission signal applied to the present specification. For example, the transmission signal may be processed by a signal processing circuit. At this time, the signal processing circuit (300) may include a scrambler (310), a modulator (320), a layer mapper (330), a precoder (340), a resource mapper (350), and a signal generator (360). At this time, as an example, the operation/function of FIG. 3 may be performed in the processor (202a, 202b) and/or the transceiver (206a, 206b) of FIG. 2. In addition, as an example, the hardware elements of FIG. 3 may be implemented in the processor (202a, 202b) and/or the transceiver (206a, 206b) of FIG. 2. For example, blocks 310 to 350 may be implemented in the processor (202a, 202b) of FIG. 2, and block 360 may be implemented in the transceiver (206a, 206b) of FIG. 2, and are not limited to the above-described embodiments.

The codeword can be converted into a wireless signal through the signal processing circuit (300) of FIG. 3. Here, the codeword is an encoded bit sequence of an information block. The information block can include a transport block (e.g., a UL-SCH transport block, a DL-SCH transport block). The wireless signal can be transmitted through various physical channels (e.g., a PUSCH, a PDSCH) of FIG. 6. Specifically, the codeword can be converted into a bit sequence scrambled by a scrambler (310). The scramble sequence used for scrambling is generated based on an initialization value, and the initialization value can include ID information of a wireless device, etc. The scrambled bit sequence can be modulated into a modulation symbol sequence by a modulator (320). The modulation scheme can include pi/2-BPSK (pi/2-binary phase shift keying), m-PSK (m-phase shift keying), m-QAM (m-quadrature amplitude modulation), etc.

The complex modulation symbol sequence can be mapped to one or more transmission layers by the layer mapper (330). The modulation symbols of each transmission layer can be mapped to the corresponding antenna port(s) by the precoder (340) (precoding). The output z of the precoder (340) can be obtained by multiplying the output y of the layer mapper (330) by a precoding matrix W of N*M. Here, N is the number of antenna ports, and M is the number of transmission layers. Here, the precoder (340) can perform precoding after performing transform precoding (e.g., DFT (discrete Fourier transform) transform) on the complex modulation symbols. In addition, the precoder (340) can perform precoding without performing transform precoding.

The resource mapper (350) can map modulation symbols of each antenna port to time-frequency resources. The time-frequency resources can include a plurality of symbols (e.g., CP-OFDMA symbols, DFT-s-OFDMA symbols) in the time domain and a plurality of subcarriers in the frequency domain. The signal generator (360) generates a wireless signal from the mapped modulation symbols, and the generated wireless signal can be transmitted to another device through each antenna. To this end, the signal generator (360) can include an inverse fast fourier transform (IFFT) module, a cyclic prefix (CP) inserter, a digital-to-analog converter (DAC), a frequency uplink converter, etc.

The signal processing process for receiving signals in a wireless device can be configured in reverse order of the signal processing process (310 to 360) of FIG. 3. For example, a wireless device (e.g., 200a and 200b of FIG. 2) can receive a wireless signal from the outside through an antenna port/transceiver. The received wireless signal can be converted into a baseband signal through a signal restorer. To this end, the signal restorer can include a frequency downlink converter, an analog-to-digital converter (ADC), a CP remover, and a fast Fourier transform (FFT) module. Thereafter, the baseband signal can be restored to a codeword through a resource demapper process, a postcoding process, a demodulation process, and a descramble process. The codeword can be restored to an original information block through decoding. Accordingly, a signal processing circuit (not shown) for a received signal may include a signal restorer, a resource de-mapper, a postcoder, a demodulator, a de-scrambler and a decoder.

Wireless device structure applicable to this specification

FIG. 4 is a drawing illustrating another example of a wireless device to which the present specification applies.

Referring to FIG. 4, the wireless device (400) corresponds to the wireless device (200a, 200b) of FIG. 2, and may be composed of various elements, components, units/units, and/or modules. For example, the wireless device (400) may include a communication unit (410), a control unit (420), a memory unit (430), and additional elements (440). The communication unit may include a communication circuit (412) and a transceiver(s) (414). For example, the communication circuit (412) may include one or more processors (202a, 202b) and/or one or more memories (204a, 204b) of FIG. 2. For example, the transceiver(s) (414) may include one or more transceivers (206a, 206b) and/or one or more antennas (208a, 208b) of FIG. 2. The control unit (420) is electrically connected to the communication unit (410), the memory unit (430), and the additional elements (440) and controls overall operations of the wireless device. For example, the control unit (420) may control electrical/mechanical operations of the wireless device based on programs/codes/commands/information stored in the memory unit (430). In addition, the control unit (420) may transmit information stored in the memory unit (430) to an external device (e.g., another communication device) via a wireless/wired interface through the communication unit (410), or store information received from an external device (e.g., another communication device) via a wireless/wired interface in the memory unit (430).

The additional element (440) may be configured in various ways depending on the type of the wireless device. For example, the additional element (440) may include at least one of a power unit/battery, an input/output unit, a driving unit, and a computing unit. Although not limited thereto, the wireless device (400) may be implemented in the form of a robot (FIG. 1, 100a), a vehicle (FIG. 1, 100b-1, 100b-2), an XR device (FIG. 1, 100c), a portable device (FIG. 1, 100d), a home appliance (FIG. 1, 100e), an IoT device (FIG. 1, 100f), a digital broadcasting terminal, a hologram device, a public safety device, an MTC device, a medical device, a fintech device (or a financial device), a security device, a climate/environmental device, an AI server/device (FIG. 1, 140), a base station (FIG. 1, 120), a network node, etc. Wireless devices may be mobile or stationary, depending on the use/service.

In FIG. 4, various elements, components, units/parts, and/or modules within the wireless device (400) may be entirely interconnected via a wired interface, or at least some may be wirelessly connected via a communication unit (410). For example, within the wireless device (400), the control unit (420) and the communication unit (410) may be wired, and the control unit (420) and the first unit (e.g., 430, 440) may be wirelessly connected via the communication unit (410). In addition, each element, component, unit/part, and/or module within the wireless device (400) may further include one or more elements. For example, the control unit (420) may be composed of one or more processor sets. For example, the control unit (420) may be composed of a set of a communication control processor, an application processor, an electronic control unit (ECU), a graphics processing processor, a memory control processor, etc. As another example, the memory unit (430) may be composed of RAM, DRAM (dynamic RAM), ROM, flash memory, volatile memory, non-volatile memory, and/or a combination thereof.

Mobile devices to which this specification applies

FIG. 5 is a drawing illustrating an example of a portable device to which the present specification applies.

FIG. 5 illustrates an example of a mobile device to which the present specification applies. The mobile device may include a smart phone, a smart pad, a wearable device (e.g., a smart watch, a smart glass), a portable computer (e.g., a laptop, etc.). The mobile device may be referred to as a mobile station (MS), a user terminal (UT), a mobile subscriber station (MSS), a subscriber station (SS), an advanced mobile station (AMS), or a wireless terminal (WT).

Referring to FIG. 5, the portable device (500) may include an antenna unit (508), a communication unit (510), a control unit (520), a memory unit (530), a power supply unit (540a), an interface unit (540b), and an input/output unit (540c). The antenna unit (508) may be configured as a part of the communication unit (510). Blocks 510 to 530/540a to 540c correspond to blocks 410 to 430/440 of FIG. 4, respectively.

The communication unit (510) can transmit and receive signals (e.g., data, control signals, etc.) with other wireless devices and base stations. The control unit (520) can control components of the portable device (500) to perform various operations. The control unit (520) can include an AP (application processor). The memory unit (530) can store data/parameters/programs/codes/commands required for operating the portable device (500). In addition, the memory unit (530) can store input/output data/information, etc. The power supply unit (540a) supplies power to the portable device (500) and can include a wired/wireless charging circuit, a battery, etc. The interface unit (540b) can support connection between the portable device (500) and other external devices. The interface unit (540b) can include various ports (e.g., audio input/output ports, video input/output ports) for connection with external devices. The input/output unit (540c) can input or output image information/signals, audio information/signals, data, and/or information input from a user. The input/output unit (540c) can include a camera, a microphone, a user input unit, a display unit (540d), a speaker, and/or a haptic module.

For example, in the case of data communication, the input/output unit (540c) obtains information/signals (e.g., touch, text, voice, image, video) input by the user, and the obtained information/signals can be stored in the memory unit (530). The communication unit (510) converts the information/signals stored in the memory into wireless signals, and can directly transmit the converted wireless signals to other wireless devices or to a base station. In addition, the communication unit (510) can receive wireless signals from other wireless devices or base stations, and then restore the received wireless signals to the original information/signals. The restored information/signals can be stored in the memory unit (530) and then output in various forms (e.g., text, voice, image, video, haptic) through the input/output unit (540c).

Physical channels and general signal transmission

In a wireless access system, a terminal can receive information from a base station through the downlink (DL) and transmit information to the base station through the uplink (UL). The information transmitted and received by the base station and the terminal includes general data information and various control information, and various physical channels exist depending on the type/purpose of the information they transmit and receive.

FIG. 6 is a diagram illustrating physical channels applicable to this specification and a signal transmission method using them.

When a terminal is powered on again from a powered-off state or enters a new cell, it performs an initial cell search task such as synchronizing with the base station at step S611. To do this, the terminal can receive a primary synchronization channel (P-SCH) and a secondary synchronization channel (S-SCH) from the base station to synchronize with the base station and obtain information such as a cell ID.

Thereafter, the terminal can receive a physical broadcast channel (PBCH) signal from the base station to obtain broadcast information within the cell. Meanwhile, the terminal can receive a downlink reference signal (DL RS: Downlink Reference Signal) in the initial cell search phase to check the downlink channel status. After completing the initial cell search, the terminal can receive a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) according to the physical downlink control channel information in step S612 to obtain more specific system information.

Thereafter, the terminal may perform a random access procedure such as steps S613 to S616 to complete connection to the base station. To this end, the terminal may transmit a preamble through a physical random access channel (PRACH) (S613), and receive a random access response (RAR) for the preamble through a physical downlink control channel and a physical downlink shared channel corresponding thereto (S614). The terminal may transmit a physical uplink shared channel (PUSCH) using scheduling information in the RAR (S615), and perform a contention resolution procedure such as receiving a physical downlink control channel signal and a physical downlink shared channel signal corresponding thereto (S616).

A terminal that has performed the procedure described above can then perform reception of a physical downlink control channel signal and/or a physical downlink shared channel signal (S617) and transmission of a physical uplink shared channel (PUSCH) signal and/or a physical uplink control channel (PUCCH) signal (S618) as a general uplink/downlink signal transmission procedure.

Control information transmitted from a terminal to a base station is collectively referred to as uplink control information (UCI). UCI includes hybrid automatic repeat and request acknowledgement/negative-ACK (HARQ-ACK/NACK), scheduling request (SR), channel quality indication (CQI), precoding matrix indication (PMI), rank indication (RI), beam indication (BI) information, etc. In this case, UCI is generally transmitted periodically through PUCCH, but depending on the embodiment (e.g., when control information and traffic data must be transmitted simultaneously), it may be transmitted through PUSCH. In addition, the terminal may aperiodically transmit UCI through PUSCH upon request/instruction from the network.

Figure 7 is a diagram illustrating the structure of a wireless frame applicable to this specification.

Uplink and downlink transmission based on the NR system can be based on frames such as those in FIG. 7. At this time, one radio frame has a length of 10 ms and can be defined by two 5 ms half-frames (half-frames, HF). One half-frame can be defined by five 1 ms subframes (subframes, SF). One subframe is divided into one or more slots, and the number of slots in a subframe can depend on subcarrier spacing (SCS). At this time, each slot can include 12 or 14 OFDM (A) symbols depending on CP (cyclic prefix). When normal CP is used, each slot can include 14 symbols. When extended CP is used, each slot can include 12 symbols. Here, the symbol may include an OFDM symbol (or CP-OFDM symbol), an SC-FDMA symbol (or DFT-s-OFDM symbol).

Table 1 shows the number of symbols per slot, the number of slots per frame, and the number of slots per subframe according to SCS when a general CP is used, and Table 2 shows the number of symbols per slot, the number of slots per frame, and the number of slots per subframe according to SCS when an extended CP is used.

In the above Tables 1 and 2, N ^slot _symb may represent the number of symbols in a slot, N ^frame,μ _slot may represent the number of slots in a frame, and N ^subframe,μ _slot may represent the number of slots in a subframe.

In addition, in a system to which the present specification is applicable, OFDM(A) numerologies (e.g., SCS, CP length, etc.) may be set differently between multiple cells that are merged into one terminal. Accordingly, the (absolute time) section of a time resource (e.g., SF, slot or TTI) (conveniently, collectively called TU (time unit)) consisting of the same number of symbols may be set differently between the merged cells.

NR can support multiple numerologies (or subcarrier spacing (SCS)) to support various 5G services. For example, when the SCS is 15 kHz, it supports wide area in traditional cellular bands, when the SCS is 30 kHz/60 kHz, it supports dense-urban, lower latency and wider carrier bandwidth, and when the SCS is 60 kHz or higher, it can support bandwidths larger than 24.25 GHz to overcome phase noise.

The NR frequency band is defined by two types of frequency ranges (FR1, FR2). FR1 and FR2 can be configured as shown in the table below. In addition, FR2 can mean millimeter wave (mmW).

In addition, as an example, the numerology described above may be set differently in a communication system to which the present specification is applicable. As an example, a Terahertz wave (THz) band may be used as a frequency band higher than the FR2 described above. In the THz band, the SCS may be set larger than in the NR system, and the number of slots may also be set differently, and is not limited to the above-described embodiment. The THz band will be described later.

Figure 8 is a drawing illustrating a slot structure applicable to this specification.

A slot contains multiple symbols in the time domain. For example, in the case of a normal CP, a slot contains 7 symbols, but in the case of an extended CP, a slot may contain 6 symbols. A carrier contains multiple subcarriers in the frequency domain. An RB (Resource Block) can be defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain.

Additionally, a Bandwidth Part (BWP) is defined as multiple consecutive (P)RBs in the frequency domain and can correspond to one numerology (e.g., SCS, CP length, etc.).

A carrier can contain up to N (e.g., 5) BWPs. Data communication is performed through activated BWPs, and only one BWP can be activated for one terminal. Each element in the resource grid is referred to as a resource element (RE), and one complex symbol can be mapped.

6G communication system

The 6G (wireless communication) system aims at (i) very high data rates per device, (ii) a very large number of connected devices, (iii) global connectivity, (iv) very low latency, (v) lower energy consumption of battery-free IoT devices, (vi) ultra-reliable connectivity, and (vii) connected intelligence with machine learning capabilities. The vision of the 6G system can be divided into four aspects: "intelligent connectivity", "deep connectivity", "holographic connectivity", and "ubiquitous connectivity", and the 6G system can satisfy the requirements as shown in Table 4 below. That is, Table 4 is a table showing the requirements of the 6G system.

At this time, 6G systems may have key factors such as enhanced mobile broadband (eMBB), ultra-reliable low latency communications (URLLC), massive machine type communications (mMTC), AI integrated communication, tactile internet, high throughput, high network capacity, high energy efficiency, low backhaul and access network congestion, and enhanced data security.

FIG. 9 is a diagram illustrating an example of a communication structure that can be provided in a 6G system applicable to this specification.

Referring to Fig. 9, the 6G system is expected to have 50 times higher simultaneous wireless communication connectivity than the 5G wireless communication system. URLLC, a key feature of 5G, is expected to become a more important technology in 6G communication by providing end-to-end delay of less than 1 ms. At this time, the 6G system will have much better volumetric spectral efficiency than the frequently used area spectral efficiency. The 6G system can provide very long battery life and advanced battery technology for energy harvesting, so that mobile devices in the 6G system may not need to be charged separately. In addition, new network characteristics in 6G may be as follows.

- Satellite integrated network: 6G is expected to be integrated with satellites to provide a global mobile constellation. The integration of terrestrial, satellite and airborne networks into a single wireless communication system could be crucial for 6G.

- Connected intelligence: Unlike previous generations of wireless communication systems, 6G is revolutionary and will update the wireless evolution from “connected things” to “connected intelligence.” AI can be applied at each stage of the communication process (or at each stage of signal processing, as described below).

- Seamless integration of wireless information and energy transfer: 6G wireless networks will transfer power to charge the batteries of devices such as smartphones and sensors. Therefore, wireless information and energy transfer (WIET) will be integrated.

- Ubiquitous super 3-dimemtion connectivity: Access to networks and core network functions of drones and very low Earth orbit satellites will create super 3-dimemtion connectivity in 6G ubiquitous.

Some general requirements from the new network characteristics of 6G as mentioned above can be as follows:

- Small cell networks: The idea of small cell networks was introduced to improve the quality of received signals as a result of increased throughput, energy efficiency, and spectrum efficiency in cellular systems. As a result, small cell networks are an essential feature for 5G and beyond 5G (5GB) communication systems. Accordingly, 6G communication systems also adopt the characteristics of small cell networks.

- Ultra-dense heterogeneous network: Ultra-dense heterogeneous networks will be another important feature of 6G communication systems. A multi-tier network composed of heterogeneous networks improves overall QoS and reduces costs.

- High-capacity backhaul: Backhaul connections are characterized by high-capacity backhaul networks to support high-capacity traffic. High-speed fiber optics and free-space optics (FSO) systems may be possible solutions to this problem.

- Radar technology integrated with mobile technology: High-precision localization (or location-based services) through communication is one of the functions of 6G wireless communication systems. Therefore, radar systems will be integrated with 6G networks.

- Softwarization and virtualization: Softwarization and virtualization are two important features that are fundamental to the design process in 5GB networks to ensure flexibility, reconfigurability, and programmability. In addition, billions of devices can be shared on a shared physical infrastructure.

Core implementation technology of 6G system

- Artificial Intelligence (AI)

The most important and newly introduced technology in the 6G system is AI. The 4G system did not involve AI. The 5G system will support partial or very limited AI. However, the 6G system will be fully AI-supported for automation. Advances in machine learning will create more intelligent networks for real-time communications in 6G. Introducing AI in communications can simplify and improve real-time data transmission. AI can use numerous analyses to determine how complex target tasks are performed. In other words, AI can increase efficiency and reduce processing delays.

Time-consuming tasks such as handover, network selection, and resource scheduling can be performed instantly using AI. AI can also play a significant role in M2M, machine-to-human, and human-to-machine communication. AI can also be a rapid communication in brain computer interface (BCI). AI-based communication systems can be supported by metamaterials, intelligent structures, intelligent networks, intelligent devices, intelligent cognitive radios, self-sustaining wireless networks, and machine learning.

Recently, there have been attempts to integrate AI with wireless communication systems, but these have been focused on the application layer, network layer, and especially deep learning in the field of wireless resource management and allocation. However, these studies are gradually developing into the MAC layer and physical layer, and in particular, there are attempts to combine deep learning with wireless transmission in the physical layer. AI-based physical layer transmission means applying signal processing and communication mechanisms based on AI drivers rather than traditional communication frameworks in terms of fundamental signal processing and communication mechanisms. For example, it can include deep learning-based channel coding and decoding, deep learning-based signal estimation and detection, deep learning-based multiple input multiple output (MIMO) mechanisms, and AI-based resource scheduling and allocation.

Machine learning can be used for channel estimation and channel tracking, and power allocation, interference cancellation, etc. in the physical layer of the downlink (DL). Machine learning can also be used for antenna selection, power control, and symbol detection in MIMO systems.

However, the application of DNN for transmission in the physical layer may have the following problems.

Deep learning-based AI algorithms require a large amount of training data to optimize training parameters. However, due to limitations in obtaining data in a specific channel environment as training data, a large amount of training data is used offline. This is because static training on training data in a specific channel environment can cause a conflict between the dynamic characteristics and diversity of the wireless channel.

In addition, current deep learning mainly targets real signals. However, the signals of the physical layer of wireless communication are complex signals. In order to match the characteristics of wireless communication signals, more research is needed on neural networks that detect complex domain signals.

Below, we will look at machine learning in more detail.

Machine learning refers to a series of operations that teach machines to create machines that can perform tasks that people can or cannot do. Machine learning requires data and a learning model. In machine learning, data learning methods can be broadly divided into three: supervised learning, unsupervised learning, and reinforcement learning.

Neural network learning is to minimize the error of the output. Neural network learning is a process of repeatedly inputting learning data into the neural network, calculating the neural network output and target error for the learning data, and backpropagating the neural network error from the output layer of the neural network to the input layer in the direction of reducing the error, thereby updating the weights of each node of the neural network.

Supervised learning uses training data with correct answers labeled in the training data, while unsupervised learning may not have correct answers labeled in the training data. That is, for example, in the case of supervised learning for data classification, the training data may be data in which each category is labeled in the training data. The labeled training data is input to the neural network, and the error can be calculated by comparing the output (category) of the neural network with the label of the training data. The calculated error is backpropagated in the neural network in the reverse direction (i.e., from the output layer to the input layer), and the connection weights of each node in each layer of the neural network can be updated according to the backpropagation. The amount of change in the connection weights of each node that is updated can be determined according to the learning rate. The neural network's calculation of the input data and the backpropagation of the error can constitute a learning cycle (epoch). The learning rate can be applied differently depending on the number of repetitions of the learning cycle of the neural network. For example, in the early stages of learning a neural network, a high learning rate can be used to allow the network to quickly achieve a certain level of performance, thereby increasing efficiency, while in the later stages of learning, a low learning rate can be used to increase accuracy.

Depending on the characteristics of the data, the learning method may vary. For example, if the goal is to accurately predict data transmitted from the transmitter to the receiver in a communication system, it is preferable to perform learning using supervised learning rather than unsupervised learning or reinforcement learning.

The learning model corresponds to the human brain, and the most basic linear model can be thought of, but the machine learning paradigm that uses highly complex neural network structures, such as artificial neural networks, as learning models is called deep learning.

The neural network cores used in learning methods can be broadly divided into deep neural networks (DNN), convolutional deep neural networks (CNN), and recurrent Boltzmann machines (RNN), and these learning models can be applied.

An artificial neural network is an example of multiple perceptrons connected together.

Figure 10 shows an example of a perceptron structure.

Referring to Fig. 10, when an input vector x=(x1,x2,...,xd) is input, the entire process of multiplying each component by a weight (W1,W2,...,Wd), adding up all the results, and then applying the activation function σ() is called a perceptron. A large artificial neural network structure can extend the simplified perceptron structure illustrated in Fig. 10 to apply the input vector to perceptrons of different dimensions. For convenience of explanation, input values or output values are called nodes.

Meanwhile, the perceptron structure illustrated in Fig. 10 can be explained as consisting of a total of three layers based on input and output values. An artificial neural network in which there are H perceptrons of (d+1) dimensions between the 1st layer and the 2nd layer, and K perceptrons of (H+1) dimensions between the 2nd layer and the 3rd layer can be expressed as in Fig. 4. Fig. 11 shows an example of a multilayer perceptron structure.

The layer where the input vector is located is called the input layer, the layer where the final output value is located is called the output layer, and all layers located between the input layer and the output layer are called hidden layers. The example in Fig. 4 shows three layers, but when counting the number of actual artificial neural network layers, the input layer is excluded, so it can be viewed as a total of two layers. The artificial neural network is composed of perceptrons of basic blocks connected in two dimensions.

The above-mentioned input layer, hidden layer, and output layer can be applied jointly not only to multilayer perceptron but also to various artificial neural network structures such as CNN and RNN, which will be described later. The more hidden layers there are, the deeper the artificial neural network becomes, and the machine learning paradigm that uses a sufficiently deep artificial neural network as a learning model is called deep learning. In addition, the artificial neural network used for deep learning is called a deep neural network (DNN: Deep neural network).

The deep neural network illustrated in Fig. 12 is a multilayer perceptron composed of eight hidden layers and eight output layers. The multilayer perceptron structure is expressed as a fully-connected neural network. In a fully-connected neural network, there is no connection relationship between nodes located in the same layer, and there is a connection relationship only between nodes located in adjacent layers. DNN has a fully-connected neural network structure and is composed of a combination of multiple hidden layers and activation functions, and can be usefully applied to identify correlation characteristics between inputs and outputs. Here, the correlation characteristic can mean the joint probability of inputs and outputs.

Meanwhile, depending on how multiple perceptrons are connected to each other, various artificial neural network structures different from the aforementioned DNN can be formed.

In DNN, nodes located within a single layer are arranged in a one-dimensional vertical direction. However, Fig. 13 can assume a case where nodes are arranged two-dimensionally, with w nodes in width and h nodes in height (convolutional neural network structure of Fig. 6). In this case, since a weight is added to each connection in the connection process from one input node to the hidden layer, a total of h×w weights must be considered. Since there are h×w nodes in the input layer, a total of h2w2 weights are required between two adjacent layers.

The convolutional neural network of Fig. 13 has a problem in that the number of weights increases exponentially according to the number of connections. Therefore, instead of considering the connections of all modes between adjacent layers, it assumes that there is a small filter, and performs weighted sum and activation function operations on the overlapping portions of the filters, as in Fig. 7.

One filter has a weight corresponding to the number of its size, and learning of the weight can be performed so that a specific feature on the image can be extracted as a factor and output. In Fig. 14, a 3×3 sized filter is applied to the 3×3 area at the upper left of the input layer, and the output value resulting from performing weighted sum and activation function operations for the corresponding node is stored in z22.

The above filter performs weighted sum and activation function operations while moving horizontally and vertically at a certain interval while scanning the input layer, and places the output value at the current filter position. This operation method is similar to the convolution operation for images in the field of computer vision, so a deep neural network with this structure is called a convolutional neural network (CNN), and the hidden layer generated as a result of the convolution operation is called a convolutional layer. In addition, a neural network with multiple convolutional layers is called a deep convolutional neural network (DCNN).

In the convolution layer, the number of weights can be reduced by calculating the weighted sum by including only the nodes located in the area covered by the filter at the node where the current filter is located. As a result, one filter can be used to focus on features for a local area. Accordingly, CNN can be effectively applied to image data processing where physical distance in a two-dimensional area is an important judgment criterion. Meanwhile, CNN can apply multiple filters immediately before the convolution layer, and can also generate multiple output results through the convolution operation of each filter.

On the other hand, there may be data for which sequence characteristics are important depending on the data properties. Considering the length variability and chronological relationship of these sequence data, the structure that applies the method of inputting one element of the data sequence at each time step and inputting the output vector (hidden vector) of the hidden layer output at a specific time together with the next element in the sequence to an artificial neural network is called a recurrent neural network structure.

Figure 15 shows an example of a neural network structure in which a recurrent loop exists.

Referring to Fig. 15, a recurrent neural network (RNN) is a structure that inputs elements (x1(t), x2(t), ,..., xd(t)) of a certain time point t in a data sequence into a fully connected neural network, and applies a weighted sum and an activation function along with the hidden vector (z1(t-1), z2(t-1),..., zH(t-1)) of the immediately previous time point t-1. The reason for transmitting the hidden vector to the next time point in this way is because the information in the input vectors of the previous time points is considered to be accumulated in the hidden vector of the current time point.

Figure 16 shows an example of the operational structure of a recurrent neural network.

Referring to Figure 16, the recurrent neural network operates in a predetermined time order on the input data sequence.

When the input vector (x1(t), x2(t), ,..., xd(t)) at time point 1 is input to the recurrent neural network, the hidden vector (z1(1), z2(1),..., zH(1)) is input together with the input vector (x1(2), x2(2),..., xd(2)) at time point 2, and the hidden layer vector (z1(2), z2(2),..., zH(2)) is determined through the weighted sum and activation function. This process is repeatedly performed until time points 2, 3, ,,, and T.

Meanwhile, when multiple hidden layers are arranged in a recurrent neural network, it is called a deep recurrent neural network (DRNN). Recurrent neural networks are designed to be usefully applied to sequence data (e.g. natural language processing).

It is a neural network core used in a learning manner, and includes various deep learning techniques such as DNN, CNN, RNN, Restricted Boltzmann Machine (RBM), Deep Belief Network (DBN), and Deep Q-Network, and can be applied to fields such as computer vision, speech recognition, natural language processing, and speech/signal processing.

Recently, there have been attempts to integrate AI with wireless communication systems, but these have been focused on the application layer, network layer, and especially deep learning in the field of wireless resource management and allocation. However, these studies are gradually developing into the MAC layer and the Physical layer, and in particular, there are attempts to combine deep learning with wireless transmission in the Physical layer. AI-based physical layer transmission means applying signal processing and communication mechanisms based on AI drivers, rather than traditional communication frameworks, in terms of fundamental signal processing and communication mechanisms. For example, it can include deep learning-based channel coding and decoding, deep learning-based signal estimation and detection, deep learning-based MIMO mechanism, and AI-based resource scheduling and allocation.

THz(Terahertz) communication

THz communication can be applied in 6G systems. For example, the data transmission rate can be increased by increasing the bandwidth. This can be done by using sub-THz communication with a wide bandwidth and applying advanced massive MIMO technology.

FIG. 17 is a diagram illustrating an electromagnetic spectrum applicable to the present specification. As an example, referring to FIG. 17, THz waves, also known as sub-millimeter radiation, generally represent a frequency band between 0.1 THz and 10 THz with a corresponding wavelength in the range of 0.03 mm-3 mm. The 100 GHz-300 GHz band range (Sub THz band) is considered to be a major part of the THz band for cellular communications. Adding the Sub-THz band to the mmWave band will increase the capacity of 6G cellular communications. Among the defined THz bands, 300 GHz-3 THz is in the far infrared (IR) frequency band. The 300 GHz-3 THz band is a part of the optical band, but is at the boundary of the optical band, just behind the RF band. Therefore, this 300 GHz-3 THz band exhibits similarities with RF.

Key characteristics of THz communications include (i) widely available bandwidth to support very high data rates, and (ii) high path loss at high frequencies (highly directional antennas are essential). The narrow beam widths generated by highly directional antennas reduce interference. The small wavelength of THz signals allows a much larger number of antenna elements to be integrated into devices and BSs operating in this band. This allows the use of advanced adaptive array techniques to overcome range limitations.

optical wireless technology

OWC (optical wireless communication) technology is planned for 6G communication in addition to RF-based communication for all possible device-to-access networks. These networks connect to network-to-backhaul/fronthaul network connections. OWC technology has already been used since 4G communication systems, but it will be used more widely to meet the needs of 6G communication systems. OWC technologies such as light fidelity, visible light communication, optical camera communication, and free space optical (FSO) communication based on optical bands are already well known technologies. Optical wireless technology-based communication can provide very high data rates, low latency, and secure communication. LiDAR (light detection and ranging) can also be used for ultra-high-resolution 3D mapping in 6G communication based on optical bands.

FSO Backhaul Network

The characteristics of the transmitter and receiver of the FSO system are similar to those of the optical fiber network. Therefore, the data transmission of the FSO system is similar to that of the optical fiber system. Therefore, FSO can be a good technology to provide backhaul connections in 6G systems together with optical fiber networks. With FSO, very long-distance communication is possible even at distances of more than 10,000 km. FSO supports large-capacity backhaul connections for remote and non-remote areas such as the ocean, space, underwater, and isolated islands. FSO also supports cellular base station connections.

Massive MIMO technology

One of the key technologies to improve spectral efficiency is the application of MIMO technology. As MIMO technology improves, spectral efficiency also improves. Therefore, massive MIMO technology will be important in 6G systems. Since MIMO technology utilizes multiple paths, multiplexing technology and beam generation and operation technology suitable for the THz band must also be considered so that data signals can be transmitted through more than one path.

Blockchain

Blockchain will be an important technology for managing large amounts of data in future communication systems. Blockchain is a form of distributed ledger technology, where a distributed ledger is a database distributed across a large number of nodes or computing devices. Each node replicates and stores an identical copy of the ledger. Blockchain is managed by a peer-to-peer (P2P) network. It can exist without being managed by a central authority or server. Data in a blockchain is collected together and organized into blocks. Blocks are linked together and protected using cryptography. Blockchain perfectly complements large-scale IoT with its inherently enhanced interoperability, security, privacy, reliability, and scalability. Thus, blockchain technology offers several features such as interoperability between devices, traceability of large amounts of data, autonomous interaction of other IoT systems, and large-scale connection stability of 6G communication systems.

3D Networking

6G systems support vertical expansion of user communications by integrating terrestrial and air networks. 3D BS will be provided via low-orbit satellites and UAVs. Adding a new dimension in terms of altitude and associated degrees of freedom makes 3D connections significantly different from existing 2D networks.

Quantum Communication

In the context of 6G networks, unsupervised reinforcement learning of networks is promising. Supervised learning methods cannot label the massive amount of data generated by 6G. Unsupervised learning does not require labeling. Therefore, this technology can be used to autonomously build representations of complex networks. Combining reinforcement learning and unsupervised learning can allow networks to operate in a truly autonomous manner.

unmanned aerial vehicle

Unmanned aerial vehicles (UAVs) or drones will be a key element in 6G wireless communications. In most cases, high-speed data wireless connectivity is provided using UAV technology. Base station entities are installed on UAVs to provide cellular connectivity. UAVs have certain features that are not found in fixed base station infrastructure such as easy deployment, robust line-of-sight links, and freedom of movement with controlled mobility. During emergency situations such as natural disasters, deployment of terrestrial communication infrastructure is not economically feasible and sometimes cannot provide services in volatile environments. UAVs can easily handle such situations. UAVs will be a new paradigm in wireless communications. This technology facilitates three basic requirements of wireless networks namely eMBB, URLLC, and mMTC. UAVs can also support several purposes such as enhancing network connectivity, fire detection, disaster emergency services, security and surveillance, pollution monitoring, parking monitoring, and accident monitoring. Therefore, UAV technology is recognized as one of the most important technologies for 6G communications.

Cell-free Communication

Tight integration of multiple frequencies and heterogeneous communication technologies is crucial in 6G systems. As a result, users can seamlessly move from one network to another without having to make any manual configuration on their devices. The best network among the available communication technologies will be automatically selected. This will break the limitations of the cell concept in wireless communications. Currently, user movement from one cell to another causes too many handovers in dense networks, resulting in handover failures, handover delays, data loss, and ping-pong effects. 6G cell-free communications will overcome all these and provide better QoS. Cell-free communications will be achieved through multi-connectivity and multi-tier hybrid technologies and different heterogeneous radios in the devices.

Integrated wireless information and energy transfer (WIET)

WIET uses the same fields and waves as wireless communication systems. In particular, sensors and smartphones will be charged using wireless power transfer during communication. WIET is a promising technology for extending the life of battery-powered wireless systems. Therefore, battery-less devices will be supported in 6G communications.

Integration of sensing and communication

Autonomous wireless networks are capable of continuously sensing dynamically changing environmental conditions and exchanging information between different nodes. In 6G, sensing will be tightly integrated with communications to support autonomous systems.

Integration of Access Backhaul Networks

In 6G, the density of access networks will be enormous. Each access network will be connected to backhaul connections such as fiber and FSO networks. To cope with the very large number of access networks, there will be tight integration between access and backhaul networks.

Holographic Beamforming

Beamforming is a signal processing procedure that adjusts an array of antennas to transmit a wireless signal in a specific direction. It is a subset of smart antennas or advanced antenna systems. Beamforming technology has several advantages such as high signal-to-noise ratio, interference avoidance and rejection, and high network efficiency. Hologram beamforming (HBF) is a new beamforming method that is quite different from MIMO systems because it uses software-defined antennas. HBF will be a very effective approach for efficient and flexible transmission and reception of signals in multi-antenna communication devices in 6G.

Big Data Analysis

Big data analytics is a complex process for analyzing a variety of large data sets or big data. This process ensures complete data management by finding information such as hidden data, unknown correlations, and customer tendencies. Big data is collected from various sources such as video, social networks, images, and sensors. This technology is widely used to process massive data in 6G systems.

large intelligent surface (LIS)

In the case of THz band signals, since the straightness is strong, many shadow areas may be created due to obstacles. LIS technology becomes important because it can expand the communication area, enhance communication stability, and provide additional value-added services by installing LIS near these shadow areas. LIS is an artificial surface made of electromagnetic materials and can change the propagation of incoming and outgoing radio waves. LIS can be seen as an extension of massive MIMO, but it has different array structures and operating mechanisms from massive MIMO. In addition, LIS has the advantage of low power consumption because it operates as a reconfigurable reflector with passive elements, that is, it passively reflects signals without using an active RF chain. In addition, since each passive reflector of LIS must independently adjust the phase shift of the incident signal, it can be advantageous for wireless communication channels. By appropriately adjusting the phase shift via the LIS controller, the reflected signal can be collected at the target receiver to boost the received signal power.

Terahertz (THz) wireless communications

FIG. 18 is a diagram illustrating a THz communication method applicable to this specification.

Referring to Fig. 18, THz wireless communication is a wireless communication using THz waves having a frequency of approximately 0.1 to 10 THz (1 THz = 1012 Hz), and may refer to terahertz (THz) band wireless communication using a very high carrier frequency of 100 GHz or higher. THz waves are located between the RF (Radio Frequency)/millimeter (mm) and infrared bands, and (i) compared to visible light/infrared rays, they penetrate non-metallic/non-polarizable materials well, and compared to RF/millimeter waves, they have a shorter wavelength, so they have high straightness and can enable beam focusing.

In addition, since the photon energy of THz waves is only a few meV, it has the characteristic of being harmless to the human body. The frequency band expected to be used for THz wireless communication may be the D-band (110 GHz to 170 GHz) or H-band (220 GHz to 325 GHz) bands where propagation loss due to absorption of molecules in the air is small. In addition to 3GPP, standardization discussions for THz wireless communication are being centered around the IEEE 802.15 THz WG (working group), and standard documents issued by the TG (task group) of IEEE 802.15 (e.g., TG3d, TG3e) can specify or supplement the contents described in this specification. THz wireless communication can be applied to wireless cognition, sensing, imaging, wireless communication, THz navigation, etc.

Specifically, referring to FIG. 18, THz wireless communication scenarios can be classified into a macro network, a micro network, and a nanoscale network. In a macro network, THz wireless communication can be applied to vehicle-to-vehicle (V2V) connections and backhaul/fronthaul connections. In a micro network, THz wireless communication can be applied to fixed point-to-point or multi-point connections such as indoor small cells, wireless connections in data centers, and near-field communications such as kiosk downloading. Table 5 below is a table showing examples of technologies that can be used in THz waves.

FIG. 19 is a diagram illustrating a THz wireless communication transceiver applicable to the present specification.

Referring to Figure 19, THz wireless communication can be classified based on the method for THz generation and reception. THz generation methods can be classified into optical device or electronic device-based technologies.

At this time, methods for generating THz using electronic components include a method using a semiconductor component such as a resonant tunneling diode (RTD), a method using a local oscillator and a multiplier, a MMIC (monolithic microwave integrated circuits) method using an integrated circuit based on a compound semiconductor HEMT (high electron mobility transistor), and a method using a Si-CMOS-based integrated circuit. In the case of Fig. 19, a doubler (tripler, multiplier, multiplier) is applied to increase the frequency, and it passes through a subharmonic mixer and is radiated by an antenna. Since the THz band forms a high frequency, a doubler is essential. Here, the multiplier is a circuit that has an output frequency that is N times that of the input, and matches it to a desired harmonic frequency and filters out all remaining frequencies. In addition, beamforming can be implemented by applying an array antenna, etc. to the antenna of Fig. 19. In Figure 19, IF represents intermediate frequency, tripler and multipler represent multipliers, PA represents a power amplifier, LNA represents a low noise amplifier, and PLL represents a phase-locked loop.

FIG. 20 is a diagram illustrating a THz signal generation method applicable to the present specification. In addition, FIG. 21 is a diagram illustrating a wireless communication transceiver applicable to the present specification.

Referring to FIGS. 20 and 21, the optical device-based THz wireless communication technology refers to a method of generating and modulating a THz signal using an optical device. The optical device-based THz signal generation technology is a technology that generates an ultra-high-speed optical signal using a laser and an optical modulator, and converts it into a THz signal using an ultra-high-speed optical detector. Compared to a technology that uses only electronic devices, this technology makes it easy to increase the frequency, enables high-power signal generation, and obtains flat response characteristics in a wide frequency band. In order to generate a THz signal based on an optical device, a laser diode, a wideband optical modulator, and an ultra-high-speed optical detector are required, as illustrated in FIG. 20. In the case of FIG. 20, light signals of two lasers with different wavelengths are combined to generate a THz signal corresponding to the wavelength difference between the lasers. In Fig. 20, an optical coupler refers to a semiconductor device that transmits an electrical signal using optical waves to provide electrical isolation and coupling between circuits or systems, and a uni-travelling carrier photo-detector (UTC-PD) is one of the photodetectors, which uses electrons as active carriers and is a device that reduces the travel time of electrons by bandgap grading. UTC-PD is capable of detecting light at 150 GHz or higher. In Fig. 20, EDFA (erbium-doped fiber amplifier) represents an erbium-doped fiber amplifier, PD (photo detector) represents a semiconductor device that can convert an optical signal into an electrical signal, OSA represents an optical sub assembly that modularizes various optical communication functions (e.g., photoelectric conversion, electro-optical conversion, etc.) into a single component, and DSO represents a digital storage oscilloscope.

Fig. 22 is a drawing illustrating a transmitter structure applicable to the present specification. In addition, Fig. 23 is a drawing illustrating a modulator structure applicable to the present specification.

Referring to FIGS. 22 and 23, a general optical source of a laser can be passed through an optical wave guide to change the phase of a signal, etc. At this time, data is loaded by changing the electrical characteristics through a microwave contact, etc. Therefore, the optical modulator output is formed as a modulated waveform. An optical/electrical modulator (O/E converter) can generate a THz pulse according to an optical rectification operation by a nonlinear crystal, an optical/electrical conversion by a photoconductive antenna, an emission from a bunch of relativistic electrons, etc. A terahertz pulse (THz pulse) generated in the above manner can have a length in the unit of femto second to pico second. An optical/electronic converter (O/E converter) performs down conversion by utilizing the non-linearity of the device.

Considering the THz spectrum usage, it is likely that multiple contiguous GHz bands will be used for THz systems, either fixed or for mobile service. Based on an outdoor scenario, the available bandwidth can be classified based on an oxygen attenuation of 10^2 dB/km in the spectrum up to 1 THz. Accordingly, a framework may be considered in which the available bandwidth is composed of multiple band chunks. As an example of the framework, if the length of a THz pulse for one carrier is set to 50 ps, the bandwidth (BW) becomes approximately 20 GHz.

Effective down conversion from the infrared band to the terahertz band (THz band) depends on how to utilize the nonlinearity of the optical/electrical converter (O/E converter). That is, in order to down convert to a desired terahertz band (THz band), it is required to design an optical/electrical converter (O/E converter) that has the most ideal nonlinearity for moving to the terahertz band (THz band). If an optical/electrical converter (O/E converter) that does not match the target frequency band is used, there is a high possibility that errors will occur in the amplitude and phase of the pulse.

In a single carrier system, a terahertz transmit/receive system can be implemented using one optical-to-electrical converter. Depending on the channel environment, in a multi-carrier system, the number of optical-to-electrical converters may be required as many as the number of carriers. In particular, in the case of a multi-carrier system that utilizes multiple widebands according to a plan related to the aforementioned spectrum usage, this phenomenon will be prominent. In this regard, a frame structure for the multi-carrier system can be considered. A signal down-converted based on an optical-to-electrical converter can be transmitted in a specific resource area (e.g., a specific frame). The frequency area of the specific resource area can include a plurality of chunks. Each chunk can be composed of at least one component carrier (CC).

Here, the wireless communication technology implemented in the wireless device (200a, 200b) of the present specification may include not only LTE, NR, and 6G, but also Narrowband Internet of Things for low-power communication. At this time, for example, NB-IoT technology may be an example of LPWAN (Low Power Wide Area Network) technology, and may be implemented with standards such as LTE Cat NB1 and/or LTE Cat NB2, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device (XXX, YYY) of the present specification may perform communication based on LTE-M technology. At this time, for example, LTE-M technology may be an example of LPWAN technology, and may be called by various names such as eMTC (enhanced Machine Type Communication). For example, the LTE-M technology can be implemented by at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-Bandwidth Limited), 5) LTE-MTC, 6) LTE Machine Type Communication, and/or 7) LTE M, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device (200a, 200b) of the present specification can include at least one of ZigBee, Bluetooth, and Low Power Wide Area Network (LPWAN) considering low-power communication, and is not limited to the above-described names. For example, the ZigBee technology can create PAN (personal area networks) related to small/low-power digital communication based on various standards such as IEEE 802.15.4, and can be called by various names.

The contents discussed above can be applied in combination with the embodiments proposed in the present specification to be described later, or can be supplemented to clarify the technical features of the embodiments proposed in the present specification. The embodiments described below are distinguished only for the convenience of explanation, and it goes without saying that some components of one embodiment can be replaced with some components of another embodiment or applied in combination with each other. The present disclosure relates to a wireless transmission device, method, and procedure for transmitting the same data from one device (e.g., a base station or an AP, etc.) to multiple devices (e.g., terminals, etc.).

NR MBS (Multicast/Broadcast Service) is a technology that can transmit the same data to multiple terminals using the same radio resources. The base station can transmit the same data to multiple terminals using the same downlink radio resources, i.e., PDSCH.

To increase transmission reliability, the base station can transmit the same data repeatedly multiple times or perform retransmission according to HARQ-ACK (Hybrid Automatic Repeat request Acknowledgement) feedback. In case of repeated transmission, the same data can be transmitted repeatedly for each slot. In case of retransmission according to HARQ-ACK feedback, the base station can be configured to transmit ACK or NACK for each terminal, or can be configured to transmit nothing when no error occurs (Discontinuous Transmission, DTX) and to transmit NACK only when an error occurs. In case of transmitting NACK only when an error occurs, the base station can configure multiple terminals to share the same PUCCH resource.

The present disclosure describes a device, method, and procedure that allows one device (e.g., a base station or an AP, etc.) to efficiently transmit the same data to multiple devices (e.g., terminals, etc.) in a wireless communication system.

NR MBS can increase transmission reliability by repeatedly transmitting the same data in each slot, but it has the disadvantage of increasing the usage of radio resources and increasing transmission delay. In case of retransmission according to HARQ-ACK feedback, the efficiency of radio resource usage may decrease because the entire data must be retransmitted.

The present disclosure describes a wireless transmission device, method and procedure that can increase transmission reliability, reduce transmission delay, and improve wireless resource efficiency in initial transmission and retransmission by using an outer erasure code when one device transmits the same data to multiple devices through the same wireless resource.

The symbols/abbreviations/terms used in this disclosure are as follows.

- ACK: Acknowledgement

- AP: Access Point

- API: Additional PCB Indicator

- BLER: Block Error Rate

- CB: Code Block

- CRC: Cyclic Redundancy Check

- DCB: Data Code Block

- DCI: Downlink Control Information

- HARQ: Hybrid Automatic Repeat reQuest

- HARQ-ACK: Hybrid Automatic Repeat reQuest Acknowledgment

- MBS: Multicast/Broadcast Service

- NACK: Negative Acknowledgment

- NR: New Radio

- PCB: Parity Code Block

- PDCCH: Physical Downlink Control Channel

- PDSCH: Physical Downlink Shared Channel

- PUCCH: Physical Uplink Control Channel

- RB: Resource Block

- RRC: Radio Resource Control

- RV: Redundancy Version

- TB: Transport Block

- UE: User Equipment

FIG. 24 is a diagram illustrating an example of a communication system according to one embodiment of the present disclosure.

The present disclosure focuses on multicast. However, the present disclosure is not limited to multicast and can also be applied to broadcast. The present disclosure focuses on systematic erasure codes. However, the present disclosure is not limited to systematic erasure codes and can also be applied to non-systematic erasure codes. In addition, the present disclosure focuses on optimal erasure codes which require k error-free data and parity symbols to recover k data symbols including erroneous symbols. However, the present disclosure is not limited to optimal erasure codes and the present disclosure can also be applied to sub-optimal/near-optimal erasure codes which require k or slightly more error-free data and parity symbols, such as Raptor codes.

Referring to FIG. 24, a communication system according to an embodiment of the present disclosure may include one base station (BS) and multiple terminals (UE1 to UE5). Meanwhile, only one base station and five terminals (UE1 to UE5) are illustrated in FIG. 24, but this is only an example and is not limited thereto. The base station may transmit the same data to multiple terminals. The base station may transmit the same data to multiple terminals using the same downlink resource. For example, the base station may transmit data to multiple terminals in the following manner.

FIG. 25 is a diagram illustrating an example of a data transmission method according to one embodiment of the present disclosure.

Referring to FIG. 25, a base station can transmit data to multiple terminals by dividing a transport block (TB) into multiple code blocks (CB), applying an erasure code, and then applying an inner channel code. Here, an LDPC (Low Density Parity Check) code, a Turbo code, or a Polar code can be used as the inner channel code, and a Raptor code, a Random Linear code, or a RS (Reed-Solomon) code can be used as the outer channel code.

The base station can divide a TB into multiple DCBs (Data Code Blocks) and perform erasure encoding between the CBs to generate one or more PCBs (Parity Code Blocks). Each CB can be transmitted to multiple terminals after undergoing internal channel coding, rate matching, and modulation after adding a CRC (Cyclic Redundancy Check).

The plurality of terminals can perform demodulation, de-rate matching, and inner channel decoding on the received signal, and then check the CRC for each CB to check whether there is an error. If at least one DCB has an error, and a sufficient number of CBs including both the DCB and the PCB are received without errors to perform erasure decoding, the terminals can perform erasure decoding between CBs to recover remaining transmission errors. If there are DCBs with errors even after the erasure decoding process, the terminals can request retransmission to the base station. The terminals can request retransmission to the base station through HARQ-ACK feedback. The base station can receive HARQ-ACK feedback from the terminals. The base station can perform retransmission by transmitting the CB to the terminals. For example, the base station can transmit the CB to the plurality of terminals in the following manner.

FIG. 26 is a diagram illustrating an example of a CB transmission method according to one embodiment of the present disclosure.

Referring to FIG. 26, a base station can divide one TB (Transmission block) into 16 DCBs and add three PCBs to generate a total of 19 CBs. The base station can transmit the 19 CBs to multiple terminals. In this case, we can consider a case where two DCBs have errors in an arbitrary terminal. The two DCBs in which errors occurred may not be recovered by internal channel decoding. The two DCBs in which errors occurred can be recovered by external erasure decoding using 17 error-free CBs including three PCBs (PCB 1, PCB 2, and PCB 3). In this case, transmission delay can be reduced because DCBs that were not recovered by internal channel decoding can be recovered without retransmission.

Referring again to FIG. 24, the BLER of a TB based on the number of all CBs (including DCBs and PCBs), the number of DCBs, the number of PCBs, and the BLER of each CB can be expressed as in the following mathematical expression 1.

는 TB의 BLER일 수 있고, n은 전체 CB의 개수일 수 있고, k는 DCB의 개수일 수 있고, m은 PCB의 개수일 수 있고, p는 CB들 각각의 BLER일 수 있다. 여기에서, PCB의 개수는 n-k일 수 있다. In mathematical expression 1,

can be the BLER of TB, n can be the number of total CBs, k can be the number of DCBs, m can be the number of PCBs, and p can be the BLER of each of the CBs. Here, the number of PCBs can be nk.

The TB size may vary depending on the amount of data that the base station wants to transmit, available radio resources, channel conditions, etc. As the TB size varies, the number of DCBs included in one TB may vary, and the number of PCBs required to achieve the target BLER may also vary. Therefore, a method may be required in which the transmitter and receiver, or the base station and terminal, can dynamically share the number of DCBs and PCBs.

When the CB BLER is constant at 0.01, the maximum number of DCBs (k _max ) that can achieve the target TB BLER for each number of PCBs (m) and the corresponding maximum number of total CBs (n _max ) can be expressed as in Table 6.

Table 6 may be about the given target TB BLER and CB BLER as described above, and may be generated based on mathematical expression 1. Referring to Table 6, the maximum number of total CBs may be equal to the maximum number of DCBs plus the number of PCBs. For example, when a base station transmits two PCBs together with multiple DCBs, the number of DCBs for the TB BLER to be less than or equal to 0.001 may be less than or equal to 17. Also, the total number of CBs may be less than or equal to 19, which is the sum of 17 and 2.

When a base station transmits the same TB to multiple terminals as in Fig. 24, the TB group BLER, which is the probability that a TB transmission error occurs in at least one of the multiple terminals, can be expressed as in the following mathematical expression 2.

는 TB 그룹 BLER일 수 있고, p_u는 각 단말의 CB BLER일 수 있고,

는 복수의 단말의 개수일 수 있다.In mathematical expression 2,

can be a TB group BLER, and p _u can be a CB BLER of each terminal,

can be a number of multiple terminals.

When the CB BLER of all terminals is equal to p, the TB group BLER can be expressed as the following mathematical expression 3.

For example, when the CB BLER is a preset value, the minimum number of PCBs required according to the number of DCBs required for the TB group BLER to be less than or equal to the preset value is as follows.

FIG. 27 is a diagram illustrating an example of a minimum number of PCBs according to the number of DCBs required for a TB group BLER to be less than or equal to a preset value according to one embodiment of the present disclosure.

Figure 27 shows the minimum number of PCBs according to the number of DCBs and the number of terminals required to ensure that the TB group BLER is 0.001 or less when the CB BLER is 0.01.

Referring to Fig. 27, it can be determined that additional PCBs are required as the number of terminals increases based on the case where there is one terminal. Therefore, the base station can determine the number of PCBs to achieve the target TB group BLER based on the number of DCBs and the number of terminals. For example, the base station can determine the number of PCBs in the following manner.

The base station can determine the total number of PCBs (m) by considering both the basic number of PCBs (m ₀ ), which is the number of PCBs required to achieve the target TB BLER when there is only one terminal, and the number of additional PCBs (m ₁ ), which is the number of PCBs additionally required to achieve the target TB BLER as the number of terminals increases.

The base station can determine the number of basic PCBs (m ₀ ) based on a table based on target TB BLER and CB BLER. For example, the base station can determine the number of basic PCBs (m ₀ ) based on Table 6 described above.

The base station can generate a table including information about the number of basic PCBs (m ₀ ) and the maximum number of total CBs (n _max ). Here, the maximum number of total CBs (n _max ) may be the maximum number of total CBs corresponding to the number of basic PCBs (m ₀ ). For example, when the target TB BLER is 0.001 and the CB BLER is 0.01, the base station can generate a table including information about the number of basic PCBs (m ₀ ) and the maximum number of total CBs (n _max ), as shown in Table 7 below.

The base station can transmit to multiple terminals a table including information about the number of basic PCBs (m ₀ ) and the maximum number of total CBs (n _max ). For example, the base station can transmit to multiple terminals a table including information about the number of basic PCBs (m ₀ ) and the maximum number of total CBs (n _max ) via an RRC message.

In one embodiment, the base station may generate a table including information about an additional PCB indicator (API) and the number (m ₁ ) of the additional PCBs. The number of additional PCBs may be the number (m ₁ ) of additional PCBs corresponding to the additional PCB indicator (API). For example, when the additional PCB indicator is transmitted via DCI, the base station may generate a table including information about an additional PCB indicator (API) and the number (m ₁ ) of the additional PCBs as in Table 8.

The base station can transmit to the multiple terminals a table including information about an additional PCB indicator (API) and the number of additional PCBs (m ₁ ). For example, the base station can transmit to the multiple terminals a table including information about an additional PCB indicator (API) and the number of additional PCBs (m ₁ ) via an RRC message.

In another embodiment, the base station may not generate a table including information about the additional PCB indicator (API) and the number of additional PCBs (m ₁ ). In this case, information about the additional PCB indicator (API) and the number of additional PCBs (m ₁ ) may be specified in advance in a standard or the like.

The base station can determine the number of additional PCBs (m ₁ ). The base station can transmit information about the number of additional PCBs (m ₁ ) to a plurality of terminals. For example, the base station can transmit information about the number of additional PCBs (m ₁ ) to the plurality of terminals through DCI (Downlink Control Information). In addition, the base station can further transmit information necessary for the plurality of terminals to obtain the total number of CBs (n) to the plurality of terminals through DCI. For example, the information necessary for the plurality of terminals to obtain the total number of CBs (n) may include, but is not limited to, the number of radio resource elements (REs) allocated for data transmission, a code rate, a modulation order, and the number of layers.

When the base station transmits information about the number of additional PCBs (m ₁ ) to multiple terminals through RRC messages, etc., the RRC message must be transmitted to all multiple terminals whenever the number of terminals changes, and synchronization between the base station and all terminals may be required. Therefore, it may be efficient for the base station to transmit information about the number of additional PCBs (m ₁ ) to multiple terminals through DCI.

Each of the plurality of terminals can receive from the base station a table including information about the number of basic PCBs (m ₀ ) and the maximum number of total CBs (n _max ), a table including information about an additional PCB indicator (API) and the number of additional PCBs (m ₁ ), and information about the number of additional PCBs (m ₁ ).

For example, each of the plurality of terminals may receive from the base station a table including information about the number of basic PCBs (m ₀ ) and the maximum number of total CBs (n _max ) via an RRC message and a table including information about an additional PCB indicator (API) and the number of additional PCBs (m ₁ ). In addition, the plurality of terminals may receive from the base station information about the number of additional PCBs (m 1 ) via DCI.

Each of the plurality of terminals can obtain the number of DCBs based on a table including information about the number of basic PCBs (m ₀ ) and the maximum number of total CBs (n _max ), a table including information about an additional PCB indicator (API) and the number of additional PCBs (m ₁ ), and information about the number of additional PCBs (m1).

FIG. 28 is a flowchart of a method for obtaining the number of DCBs according to one embodiment of the present disclosure.

Referring to FIG. 28, the terminal can obtain information about the total number of CBs (n) (S2810). The terminal can obtain information about the total number of CBs (n) based on a table including information about the number of basic PCBs (m ₀ ) and the maximum number of total CBs (n _max ) included in the RRC message, a table including information about an additional PCB indicator (API) and the number of additional PCBs (m ₁ ), and information about radio resource allocation information of a PDSCH to transmit data included in the DCI and information about a modulation and coding method.

The terminal can obtain information about the number of additional PCBs (m ₁ ) (S2820). The terminal can obtain information about the number of additional PCBs (m ₁ ) based on a table including information about the number of additional PCBs (m ₁ ) and an additional PCB indicator (API) included in an RRC message and the additional PCB indicator (API) included in DCI. For example, if a table including information about the number of basic PCBs (m ₀ ) and the maximum number of total CBs (n _max ) is as in Table 7 and information about the additional PCB indicator (API) and the number of additional PCBs (m ₁ ) is as in Table 8, and if the number of total CBs (n) is 76 and the additional PCB indicator (API) is 2, the terminal can obtain 3 as the number of additional PCBs (m ₁ ) from Table 8.

The terminal can obtain information about the number of basic PCBs (m ₀ ) (S2830). The terminal can obtain information about the number of basic PCBs (m ₀ ) based on a table including information about the number of basic PCBs (m 0 ) and the maximum number of total CBs (n _max ), information about the number of total CBs (n) obtained in S2910, and information about the number of additional PCBs (m ₁ ) obtained in _{S2920, which are included in the RRC message. For example, the terminal can obtain the number of basic PCBs (m 0 )} corresponding to the smallest maximum number of total CBs (n _max ) and the maximum number of total CBs (n _max ) that is not smaller than the difference between the number of total CBs (n) and the number of additional PCBs (m ₁ ) from the table including information about the number of basic PCBs (m ₀ ) and the maximum number of total CBs (n _max ). For example, if the number of additional PCBs (m ₁ ) is 3 at step S2920, the terminal can obtain 75 as the maximum number of total CBs (n _max ) greater than or equal to 73 by subtracting 3 as the number of additional PCBs (m1) from 76 as the total number of CBs (n) based on Table 7, and can obtain 4 as the number of basic PCBs (m ₀ ) corresponding to this.

The terminal can obtain information about the number (k) of DCBs (S2840). The terminal can obtain information about the number (k) of DCBs by subtracting the number (m) of total PCBs from the number (n) of total CBs. The number (m) of total PCBs may be the sum of the number (m ₀ ) of basic PCBs and the number (m ₁ ) of additional PCBs. For example, if the number (m ₁ ) of additional PCBs is 3 in step S2920 and the number (m ₀ ) of basic PCBs is 4 in step S2930, the terminal can obtain 7 as the total number (m) of PCBs, and obtain 69 as the number (k) of DCBs by subtracting the number (m) of total PCBs, 7, from the total number (n) of CBs, 76.

Referring back to FIG. 24, some of the DCBs initially transmitted by the base station to the terminal may have transmission errors, and the terminal may not be able to recover all transmission errors of the DCBs in which errors occurred by internal channel decoding and external erasure decoding. In this case, the base station may need to retransmit the DCBs to the terminal. However, it may be inefficient for the base station to retransmit all DCBs every time a transmission error occurs. Therefore, a method may be considered in which the base station retransmits only the DCBs in which errors occurred or transmits new PCBs. Here, the method of transmitting new PCBs may be a method in which the terminal performs external erasure decoding based on the new PCBs to recover the DCBs in which errors occurred.

A base station can transmit the same data to multiple terminals located at different locations. Even if each of the multiple terminals receives the same data, errors may occur in different CBs because the channel environment from the base station is different. Therefore, when retransmitting DCBs in which errors occur, the number of DCBs to be retransmitted also increases as the number of terminals increases, and the amount of radio resources required for retransmission may increase. In this case, the base station can transmit new PCBs to the multiple terminals, and each of the multiple terminals can receive the new PCBs. Each of the multiple terminals can recover the DCBs in which errors occurred by external erasure decoding based on the new PCBs. That is, even if errors occur in different DCBs, each of the multiple terminals can recover different DCBs using the new PCBs. Therefore, even if the number of terminals increases, the amount of radio resources required for retransmission may not increase significantly.

Referring back to FIG. 26, for example, when a base station transmits 16 DCBs and 3 PCBs to two terminals, an error may occur in four DCBs, DCBs 1 to 4, in one terminal, and an error may occur in four DCBs, DCBs 13 to 16, in the other terminal. In this case, assuming that both terminals receive all remaining DCBs and PCBs without errors, since the base station transmits three PCBs together with the DCBs, neither terminal can recover the DCBs in error by external erasure decoding. When retransmitting the DCBs in error, the base station has to retransmit eight DCBs, DCBs 1 to 4 and 13 to 16, to both terminals. However, if both terminals have just one more PCB, they can recover all DCBs by external erasure decoding, and therefore it may be efficient for the base station to transmit only one new PCB to both terminals.

Each of the multiple terminals can feedback the number of additional PCBs required to the base station via PUCCH. That is, in the above example, both terminals can feedback to the base station that they need one additional new PCB. The base station can enable the multiple terminals to recover from the DCB error by retransmitting to the multiple terminals new PCBs that are greater than or equal to the largest number of additional PCBs required by each of the multiple terminals.

Referring back to FIG. 24, if terminal 1 (UE1) requires one additional PCB and terminal 2 (UE2) requires three additional PCBs, the base station can transmit the three new PCBs to multiple terminals (UE1 to UE5).

The number of additional PCBs required by each of the multiple terminals may be equal to the number of DCBs in the worst case (when all CBs fail). Therefore, in order to express all cases that each of the multiple terminals can feedback, bits sufficient to express the maximum number of DCBs may be required. For example, when the maximum number of DCBs is 100, the terminal may require 7 bits to perform HARQ-ACK feedback. In general, as the data transmission rate increases, the maximum number of DCBs also increases, and thus the number of HARQ-ACK feedback bits may also increase. In other words, PUCCH resources required for HARQ-ACK feedback may also increase.

In order to reduce the number of HARQ-ACK feedback bits, each of the multiple terminals can divide the entire range of the number of PCBs into several sections and feed back. For example, if the number of DCBs is 16 as shown in Fig. 26, when there is no DCB with an error, i.e., when it is ACK, the terminal feeds back 0 to the base station using 2 bits, and when there are 1 or more but less than 5 additional PCBs required, the terminal feeds back 1 to the base station, when there are 6 or more but less than 10 PCBs, the terminal feeds back 2 to the base station, and when there are 11 or more but less than 16 PCBs, the terminal feeds back 3 to the base station.

Dividing the entire range evenly in this way can be inefficient because the probability that 1 or 2 additional PCBs are needed is significantly higher than the probability that 15 or 16 additional PCBs are needed. Therefore, it can be efficient to divide the intervals according to the probability distribution of the number of additional PCBs that the terminal needs. For example, if the probability that the terminal needs 1 additional PCB is 33%, the probability that it needs 2 to 4 additional PCBs is 33%, and the probability that it needs 5 or more additional PCBs is 34%, then in the case of ACK, it can be efficient for the terminal to feed back 0 to the base station, for 1 additional PCB, the terminal to feed back 1 to the base station, for 2 to 4 additional PCBs, the terminal to feed back 2 to the base station, and for 5 or more additional PCBs, the terminal to feed back 3 to the base station.

Since the number of DCBs may vary depending on the amount of data and channel conditions, it may be desirable to divide the number of additional PCBs required by the terminal into sections proportional to the number of DCBs. In other words, the terminal may divide the number of additional PCBs required by the terminal unequally according to probability distribution, etc., and feed it back to the base station according to the number of DCBs.

For example, each of the plurality of terminals can generate HARQ-ACK based on a preset table regarding the number of additional PCBs required by the terminal, HARQ-ACK feedback, and a retransmission method of the base station. Each of the plurality of terminals can receive a preset table and information related to the preset table (i.e., information for completing the preset table) from the base station through an RRC message, etc. Here, the information related to the preset table can include the number of HARQ-ACK feedback bits, a range of HARQ-ACK feedback values, and parameters required to determine the HARQ-ACK feedback values. For example, the preset table can be represented as in Table 9 below.

과

는 DCB의 개수에 따라 PCB 개수의 경계를 결정하는 파라미터일 수 있다. 예를 들어, 표 9에 기반하여, 복수의 단말 각각은 미리 설정된 표와 관련된 정보로 HARQ-ACK 피드백 비트 수로 2비트, HARQ-ACK 피드백 값의 범위로 0 내지 3, HARQ-ACK 피드백 값을 결정하기 위해 필요한 파라미터들로

과

를 기지국으로부터 수신할 수 있다. In Table 9

class

may be a parameter that determines the boundary of the number of PCBs according to the number of DCBs. For example, based on Table 9, each of the plurality of terminals may be configured with 2 bits as the number of HARQ-ACK feedback bits, 0 to 3 as the range of HARQ-ACK feedback values, and parameters necessary to determine the HARQ-ACK feedback value, as information related to the preset table.

class

can be received from the base station.

Each of the plurality of terminals can generate HARQ-ACK feedback based on the preset table, Table 9, and information related to Table 9. Each of the plurality of terminals can transmit HARQ-ACK feedback to the base station.

When multiple terminals each feed back HARQ-ACK through a dedicated PUCCH, the required PUCCH may also increase as the number of terminals increases. The required PUCCH can be reduced by multiple terminals sharing PUCCH resources for HARQ-ACK. When multiple terminals share one PUCCH resource, each terminal can transmit nothing (DTX) if there is no error and transmit NACK only if there is an error.

As shown in Table 9, when there are three types of NACKs (HARQ-ACK feedback 1, 2, 3), three shared PUCCH resources can be used. If each PUCCH resource is called A, B, and C, each UE can transmit NACK only on PUCCH A to transmit HARQ-ACK feedback 1, NACK only on PUCCH B to transmit HARQ-ACK feedback 2, and NACK only on PUCCH C to transmit HARQ-ACK feedback 3. If there is no transmission error, i.e., if HARQ-ACK feedback is 0, nothing can be transmitted on all PUCCHs.

The base station can receive HARQ-ACK feedback from multiple terminals. The base station can transmit new PCBs to multiple terminals or retransmit all CBs of the initial transmission to multiple terminals based on the HARQ-ACK feedback value.

When the base station transmits new PCBs to multiple terminals according to HARQ-ACK feedback, the base station can generate PCBs according to a method preset between the base station and the multiple terminals. For example, the base station can sequentially generate new PCBs starting from the PCB immediately following the last PCB of the initial transmission according to the order in which they are generated by the external erasure encoding. That is, when the base station transmits m PCBs from PCB 1 to m to the terminals in the initial transmission, the base station can sequentially generate new PCBs starting from PCB (m+1). The base station can transmit new PCBs to multiple terminals.

When the base station retransmits all CBs of the initial transmission to multiple terminals based on HARQ-ACK feedback, the base station may retransmit all CBs to multiple terminals with a different redundancy version (RV) from the initial transmission.

과

이 각각 50 및 200인 경우, 표 9는 다음 표 10과 같이 나타낼 수 있다.For example, as shown in Fig. 26, the base station transmits 16 DCBs,

class

If these are 50 and 200 respectively, Table 9 can be expressed as Table 10 below.

If at least one of the multiple terminals feedbacks 3 with HARQ-ACK, the base station can retransmit all CBs of the initial transmission to the multiple terminals.

If none of the multiple terminals feeds back 3 as HARQ-ACK and at least one of the multiple terminals feeds back 2 as HARQ-ACK, the base station can generate four new PCBs and transmit the new PCBs to the multiple terminals. As shown in Fig. 26, if the base station transmits PCBs 1, 2, and 3 to the multiple terminals in the initial transmission, the base station can generate PCBs 4, 5, 6, and 7 as new PCBs, and transmit PCBs 4, 5, 6, and 7 to the multiple terminals.

If none of the multiple terminals feeds back 2 or 3 as HARQ-ACK and at least one of the multiple terminals feeds back 1, the base station can generate one new PCB and transmit the new PCB to the multiple terminals. As shown in Fig. 26, if the base station transmits PCBs 1, 2, and 3 to the multiple terminals in the initial transmission, the base station can generate PCB 4 as a new PCB and transmit PCB 4 to the multiple terminals.

The base station can transmit DCI including a PCB-Only Indicator (POI), which is information indicating that only PCBs are transmitted, to multiple terminals to distinguish between the case where all CBs are retransmitted in a retransmission and the case where only new PCBs are transmitted. For example, the base station can set POI to 0 when the initial transmission and all CBs are retransmitted, and to 1 when new PCBs are transmitted in a retransmission.

Multiple terminals can receive DCI from a base station. The terminals can obtain POI from the DCI. Multiple terminals can determine whether a PDSCH to be received includes DCB or only PCB based on the POI.

When multiple terminals receive new PCBs from the base station while not receiving the PDCCH transmitting the DCI with the POI value of 0 (i.e., not receiving the PDCCH of the initial transmission or the PDCCH for retransmitting all CBs), the multiple terminals may not know the CB size and the number of DCBs of the initial transmission. Therefore, the multiple terminals may not be able to recover the DCBs with only the PCBs. In this case, the multiple terminals may determine that they have not received the PDCCH of the initial transmission based on the POI. The multiple terminals may transmit a HARQ-ACK feedback requesting retransmission of all CBs to the base station.

FIG. 29 is a diagram illustrating an example of a retransmission method according to one embodiment of the present disclosure.

Figure 29 is an example of a case where a terminal that failed to receive a PDCCH during initial transmission recognizes that it failed to receive the PDCCH of the initial transmission and recovers by receiving a PDCCH for transmission of new PCBs at the retransmission request of another terminal. In Figure 29, a base station and multiple terminals can perform HARQ-ACK feedback and retransmission based on Table 10.

Referring to FIG. 29, a retransmission method according to one embodiment of the present disclosure may include 1) an initial transmission and 1st HARQ-ACK feedback step, 2) a 1st retransmission and 2nd HARQ-ACK feedback step, and 3) a 2nd retransmission step.

1) Initial transmission and 1st HARQ-ACK feedback phase

The base station may transmit DCI to terminal 1 and terminal 2 via PDCCH in the initial transmission. The DCI may include 0 as a POI value. Additionally, the base station may transmit CBs to terminal 1 and terminal 2 via PDSCH in the initial transmission. The CBs may include 16 DCBs (DCB 1 to 16) and 3 PCBs (PCB 1 to 3).

Terminal 1 can receive DCI from the base station via PDCCH. Terminal 1 can obtain 0 as a POI value via DCI. Terminal 1 can receive CBs from the base station via PDSCH. Terminal 1 can perform decoding on the CBs. In this case, an error may occur in four CBs. The four CBs can include one or more DCBs (one or more of DCB 1 to 16). Terminal 1 can generate HARQ-ACK feedback to request one new PCB. Terminal 1 can transmit the HARQ-ACK feedback to the base station.

Terminal 2 may not receive DCI from the base station via PDCCH. Also, Terminal 2 may not receive CBs from the base station via PDSCH.

2) 1st retransmission phase and 2nd HARQ-ACK feedback phase

The base station can receive HARQ-ACK feedback from terminal 1. If terminal 1 and terminal 2 are configured to feed back HARQ-ACK via shared PUCCHs, the base station may not know from which terminal the received HARQ-ACK feedback is transmitted. Therefore, the base station may not recognize that terminal 2 did not receive DCI. The base station can determine a POI value based on the HARQ-ACK feedback, and transmit a DCI including the POI value to terminal 1 and terminal 2 via a PDCCH. The POI value can be 1. In addition, the base station can generate one new PCB (PCB 4) based on the HARQ-ACK feedback. The base station can transmit the new PCB to terminal 1 and terminal 2.

Terminal 1 can receive DCI from the base station through PDCCH. Terminal 1 can obtain 1 as a POI value through DCI. Terminal 1 can receive a new PCB from the base station through PDSCH. Terminal 1 can perform recovery for DCBs in which errors occurred based on the new PCB.

Terminal 2 can receive DCI from the base station via PDCCH. Terminal 2 can obtain 1 as the POI value via DCI. Terminal 2 can determine that it has not received the PDCCH of the initial transmission. Terminal 2 can receive a new PCB from the base station via PDSCH. Terminal 2 can store the new PCB.

Terminal 2 can generate HARQ-ACK feedback to request retransmission of all CBs to receive CBs that were not received in the initial transmission. Terminal 2 can transmit the HARQ-ACK feedback to the base station.

3) Second retransmission stage

The base station can receive HARQ-ACK feedback from terminal 2. The base station can determine a POI value based on the HARQ-ACK feedback, and transmit a DCI including the POI value to terminal 2 through a PDCCH. The POI value can be 0. The base station can retransmit all CBs to terminal 2 based on the HARQ-ACK feedback. The base station can retransmit all CBs to terminal 2 with a different redundancy version from the initial transmission. Here, the redundancy version can be a self-decodable redundancy version.

Terminal 2 can receive all CBs from the base station. Meanwhile, if errors occur in some CBs during the process of terminal 2 receiving retransmission, terminal 2 may not be able to recover all DCBs. In this case, terminal 2 can perform recovery of DCBs based on the PCBs received and stored from the base station in the first retransmission.

Referring again to FIG. 24, if there is a terminal that receives DCI including 1 as a POI value through PDCCH from a base station like the terminal 2 described above among multiple terminals and receives only new PCBs through PDSCH by retransmission, the terminal can determine the number of new PCBs. The terminal can obtain the number of allocated radio resources, MCS (modulation order and code rate), and the number of layers through DCI, etc. The terminal can obtain the number of coded bits based on the obtained information. The terminal can obtain the number of coded bits based on the following mathematical expression 4.

는 코딩된 비트 수일 수 있고,

는 할당된 무선 자원의 개수일 수 있고,

은 변조 차수일 수 있고,

은 코드율일 수 있고,

는 레이어의 개수일 수 있다.In mathematical expression 4,

can be the number of coded bits,

can be the number of allocated wireless resources,

can be a modulation order,

can be a code rate,

can be the number of layers.

The terminal can determine the number of new PCBs based on the number of coded bits. The terminal can determine the number of new PCBs based on mathematical expression 5.

는 새로운 PCB들의 개수일 수 있고,

는 CB의 크기일 수 있고,

는 CB CRC(Cyclic Redundancy Check)의 길이일 수 있다. CB의 크기는 최초 전송 또는 모든 CB의 재전송 정보로부터 획득된 것일 수 있다.

can be the number of new PCBs,

can be the size of CB,

can be the length of the CB CRC (Cyclic Redundancy Check). The size of the CB can be obtained from the initial transmission or the retransmission information of all CBs.

Meanwhile, even after the base station transmits new PCBs by retransmission, there may be a terminal among multiple terminals that has not recovered all DCBs. In this case, the base station needs to perform additional retransmission. In this way, if the base station transmits PCBs more than twice by retransmission, if the base station simply transmits the PCBs in the order in which they are generated by external erasure encoding, a terminal that fails to receive a PDCCH may misjudge the index of the PCB received after the PDCCH reception failure. This is explained in detail as follows.

FIG. 30 is a diagram illustrating an example of a retransmission method according to another embodiment of the present disclosure.

Fig. 30 is an example of a case where a terminal that failed to receive the first PDCCH in two PCB transmissions incorrectly recognizes the PCB index when it succeeds in receiving the second PDCCH. In Fig. 30, the terminal and the base station can perform HARQ-ACK feedback and retransmission based on Table 10.

Referring to FIG. 30, a retransmission method according to one embodiment of the present disclosure may include 1) an initial transmission and 1st HARQ-ACK feedback step, 2) a 1st retransmission and 2nd HARQ-ACK feedback step, and 3) a 2nd retransmission step.

1) Initial transmission and 1st HARQ-ACK feedback phase

The base station may transmit DCI to terminal 1 and terminal 2 via PDCCH in the initial transmission. The DCI may include 0 as a POI value. Additionally, the base station may transmit CBs to terminal 1 and terminal 2 via PDSCH in the initial transmission. The CBs may include 16 DCBs (DCB 1 to 16) and 3 PCBs (PCB 1 to 3).

Terminal 1 can receive DCI from the base station via PDCCH. Terminal 1 can obtain 0 as a POI value via DCI. Terminal 1 can receive CBs from the base station via PDSCH. Terminal 1 can perform decoding on the CBs. In this case, terminal 1 can perform decoding on the CBs. In this case, errors may occur in 7 CBs. The 7 CBs can include 1 or more DCBs (at least one of DCB 1 to 16). Terminal 1 can generate HARQ-ACK feedback to request 4 or more new PCBs. Terminal 1 can transmit 2 to the base station as HARQ-ACK feedback.

Terminal 2 can receive DCI from the base station via PDCCH. Terminal 1 can obtain 0 as POI value via DCI. Terminal 2 can receive CBs from the base station via PDSCH. Terminal 2 can perform decoding on the CBs. In this case, errors may occur in four CBs. Terminal 1 can generate HARQ-ACK feedback to request one new PCB. Terminal 1 can transmit 1 as HARQ-ACK feedback value to the base station.

2) 1st retransmission phase and 2nd HARQ-ACK feedback phase

The base station can receive HARQ-ACK feedback from terminal 1 and terminal 2. The base station can receive 1 and 2 as HARQ-ACK feedback. The base station can determine a POI value based on the HARQ-ACK feedback, and transmit a PDCCH including the POI value to terminal 1 and terminal 2 through a PDCCH. The POI value can be 1. The base station can generate new PCBs based on the HACK-ACK feedback. The base station can generate four new PCBs (PCBs 4 to 7) so that terminal 1 and terminal 2 can recover DCBs in which errors occurred. The base station can transmit the new PCBs to terminal 1 and terminal 2.

Terminal 1 can receive DCI from a base station via PDCCH. Terminal 1 can acquire 1 as a POI value via DCI. Terminal 1 can receive new PCBs from the base station via PDSCH. Terminal 1 can perform recovery of CBs in which errors have occurred based on the new PCBs. However, an error may occur in one of the new PCBs, in which case, Terminal 1 can generate HARQ-ACK feedback to secure one additional PCB. Terminal 1 can generate 1 as HARQ-ACK. Terminal 1 can transmit HARQ-ACK to the base station. Terminal 1 can transmit 1 as HARQ-ACK to the base station.

Terminal 2 may not receive the PDCCH from the base station. Terminal 2 may not receive new PCBs from the base station and may not generate or transmit additional HARQ-ACK.

3) Second retransmission stage

The base station can receive HARQ-ACK feedback from terminal 1. The base station can determine a POI value based on the HARQ-ACK feedback, and transmit DCI including the POI value to terminal 1 and terminal 2 through PDCCH. The base station can generate a new PCB (PCB 8) based on the HARQ-ACK feedback. The base station can transmit the new PCB to terminal 1 and terminal 2.

Terminal 1 can receive DCI from the base station through PDCCH. Terminal 1 can obtain 1 as a POI value through DCI. Terminal 1 can receive a new PCB from the base station through PDSCH. Since Terminal 1 received PCBs 4 to 7 in the first retransmission step, Terminal 1 can determine the new PCB as PCB 8. Terminal 1 can recover DCBs in which errors occurred based on PCBs in which no errors occurred among the new PCBs (PCBs 4 to 8).

Terminal 2 can receive DCI from the base station via PDCCH. Terminal 1 can obtain 1 as the POI value via DCI. Terminal 1 can receive a new PCB from the base station via PDSCH. Since Terminal 2 did not receive PCBs 4 to 7 in the first retransmission step, it may incorrectly determine that the new PCB is PCB 4 instead of PCB 8.

To solve this problem, the base station and multiple terminals can set the indices of new PCBs transmitted through retransmission as follows.

In the first method, when the base station transmits only PCBs to multiple terminals by retransmission, the base station can always transmit to multiple terminals starting from the PCB following the last PCB of the initial transmission.

When a base station transmits m PCBs, PCB 1 to PCB m, to multiple terminals in an initial transmission, and the base station transmits r new PCBs to multiple terminals in a retransmission, the base station can transmit r new PCBs, PCB (m+1) to PCB (m+r), to multiple terminals regardless of the number of retransmissions.

For example, as in FIG. 26, if the base station transmits PCBs 1 to 3 to multiple terminals in the initial transmission and retransmits two new PCBs to the multiple terminals, the terminals can transmit PCBs 4 to 5 to the multiple terminals. If the base station transmits PCBs 1 to 3 to multiple terminals in the initial transmission and retransmits four new PCBs to the multiple terminals, the terminals can transmit PCBs 4 to 7 to the multiple terminals.

과

가 각각 50 및 200이고, HARQ-ACK 피드백이 1 또는 2인 경우 기지국의 재전송 방법은 표 11과 같이 나타낼 수 있다.Using the same method as above, in Table 9

class

When the values are 50 and 200, respectively, and the HARQ-ACK feedback is 1 or 2, the retransmission method of the base station can be expressed as in Table 11.

This method has the advantage that the number of PCBs to be transmitted by the base station can be flexibly determined because the index of the first PCB is determined as (m+1) without additional signaling information and the number of PCBs can be obtained by Equations 4 and 5. If retransmission is performed two or more times, the same PCBs may be transmitted repeatedly. In this case, the base station can transmit redundancy versions differently to improve the reception performance of multiple terminals.

과

가 각각 50과 200일 때 새로운 PCB 전송을 요청하는 HARQ-ACK 피드백 1 또는 2인 경우, 새로운 PCB 개수 및 시작 인덱스는 다음 표 12와 같이 나타낼 수 있다.In the second method, the base station and multiple terminals can set the starting PCB index so that the PCBs do not overlap according to the HARQ-ACK feedback and the number of PCBs. For example, in Table 9,

class

When HARQ-ACK feedback 1 or 2 requests new PCB transmission when the number of new PCBs is 50 and 200 respectively, the number of new PCBs and the starting index can be expressed as in Table 12 below.

Multiple terminals can determine the number of PCBs obtained based on Equations 4 and 5 and the indexes of the PCBs based on Table 12. Since the number of PCBs and the start index are mapped 1:1, the base station can transmit only a fixed number of PCBs. Therefore, compared to the first method, the flexibility of the base station to determine the number of PCBs to transmit may be lower, but there is an advantage in that the PCBs are not duplicated when the number of PCBs is different in two or more retransmissions. When the number of PCBs is the same in two or more retransmissions, the indexes of the PCBs can be the same, and the base station can transmit redundancy versions differently to improve the reception performance of multiple terminals.

The second method can be extended to determine the starting PCB index based on the range of the number of PCBs. The method for determining the range of the number of PCBs to be transmitted for retransmission and the starting index based on the number of additional PCBs required by the terminal and the HARQ-ACK feedback value can be expressed as shown in Table 13 below.

일 수 있다. 표 13에서

는 다음 수학식 6과 같이 나타낼 수 있다.In Table 13, the maximum value of HARQ-ACK feedback is

It can be. In Table 13.

can be expressed as the following mathematical formula 6.

는 1 이상 1024 미만의 값으로,

인 임의의

에 대하여

가 성립할 수 있다. In mathematical expression 6

is a value greater than or equal to 1 and less than 1024,

Any person

About

can be established.

를 수신한 기지국은 PCB 인덱스

부터 최소

개, 최대

개의 PCB를 전송할 수 있다. 시작 PCB 인덱스

는 다음 수학식 7과 같이 나타낼 수 있다.HARQ-ACK feedback

The base station that received the PCB index

From minimum

Dog, max

You can transfer the PCB of the dog. Start PCB index

can be expressed as the following mathematical formula 7.

인 임의의

에 대하여

가 되도록

들을 설정할 수 있다. 이 경우 각 HARQ-ACK 피드백에 대응하는 PCB 개수의 범위는 서로 배타적이다. 즉, 두 HARQ-ACK 피드백

와

가 같지 않을 경우

,

에 대응하는 PCB 개수의 범위

부터

까지와

에 대응하는 PCB 개수의 범위

부터

까지는 서로 겹치지 않는다. 따라서 복수의 단말이 수학식 4 내지 5에 기반하여 획득한 PCB 개수는 단 하나의 PCB 개수 범위에만 속하게 된다. 복수의 단말은 PCB 개수 범위에 대응하는 시작 PCB 인덱스부터 순차적으로 인덱스를 부여하여 수신한 모든 PCB의 인덱스를 결정할 수 있다.The base station is

Any person

About

To become

can be set. In this case, the range of the number of PCBs corresponding to each HARQ-ACK feedback is mutually exclusive. That is, the two HARQ-ACK feedbacks

and

If they are not the same

,

Range of PCB counts corresponding to

from

Come on

Range of PCB counts corresponding to

from

do not overlap each other. Therefore, the number of PCBs acquired by multiple terminals based on mathematical expressions 4 to 5 falls within only one PCB number range. Multiple terminals can determine the indices of all received PCBs by sequentially assigning indices from the starting PCB index corresponding to the PCB number range.

가 3이고

과

가 각각 50과 200인 경우이고, 도 26과 같이 최초 전송의 DCB 개수 k는 16, PCB 개수 m은 3인 경우

과

는 수학식 6에 따라 각각 1과 4가 되고,

과

는 수학식 7에 따라 각각 4와 7이 될 수 있다. 이 경우, 표 13은 다음 표 14와 같이 나타낼 수 있다.Table 13

is 3

class

In the case where the numbers are 50 and 200 respectively, and the number of DCBs k of the first transmission is 16 and the number of PCBs m is 3, as shown in Fig. 26,

class

According to mathematical formula 6, they are 1 and 4 respectively,

class

can be 4 and 7, respectively, according to mathematical expression 7. In this case, Table 13 can be expressed as Table 14 below.

For example, referring to Table 14, a base station that receives HARQ-ACK feedback 1 can transmit a minimum of 1 and a maximum of 3 PCBs, starting from PCB 4, to multiple terminals. When the base station transmits 3 PCBs, the base station can transmit PCBs 4 to 6 to multiple terminals. The multiple terminals can obtain the number of PCBs 3 based on Equations 4 and 5, and determine that the starting PCB index is 4 based on Table 14. Therefore, the multiple terminals can determine that the indices of the received PCBs are 4 to 6.

FIG. 31 is a flowchart of a signal transmission and reception method according to one embodiment of the present disclosure.

In FIG. 31, the method may further include a step of the terminal receiving one or more synchronization signals from the base station and a step of the terminal receiving control information from the base station before step S3110 of FIG. 31.

Referring to FIG. 31, the terminal can receive DCI from the base station (S3110). The terminal can receive DCI including first information from the base station through the first channel. The first channel can be a PDCCH.

The terminal can receive a CB from the base station (S3120). The terminal can receive the CB from the base station through a second channel. The second channel can be a PDSCH. If the CB is a CB initially transmitted from the base station, the CB can include a plurality of DCBs and at least one PCB. If the first CB is not a CB initially transmitted from the base station, the CB can include at least one PCB.

The terminal can determine whether the CB is the first transmitted CB (S3130). The terminal can determine whether the CB is the first transmitted CB based on the first information included in the DCI.

If the CB is the first transmitted CB (example of S3130), the terminal can transmit HARQ-ACK feedback requesting additional PCBs to the base station (S3140). The terminal can determine whether there are DCBs with errors among the multiple DCBs included in the CB. If there are DCBs with errors among the multiple DCBs, the terminal can obtain the number of PCBs additionally required to recover the DCBs with errors based on the number of PCBs in the CB that do not have errors, and the terminal can generate HARQ-ACK feedback based on the number of acquired PCBs.

In addition, the terminal may receive a first table (e.g., Table 9 or 10) including information about the number of PCBs for recovering DCBs in which errors occurred from the base station, information about the number of bits of HARQ-ACK feedback, and information about the number of PCBs to be transmitted from the base station to the terminal, or information necessary to generate the first table. Here, the information about the number of PCBs for recovering DCBs in which errors occurred, the information about the number of bits of HARQ-ACK feedback, and the information about the number of PCBs to be transmitted from the base station to the terminal may be determined based on the number of a plurality of DCBs included in a code block and a probability distribution of additional PCBs according to the number of the plurality of DCBs. The terminal may generate the HARQ-ACK feedback based on the number of PCBs for recovering DCBs in which errors occurred and the first table.

The terminal may receive an additional PCB from the base station (S3150). The terminal may receive, from the base station, DCI including at least one of information about the number of wireless resources of the first information and the second channel, information about the modulation order, information about the code rate, or information about the number of layers, through the first channel.

The terminal can receive PCBs greater than the minimum number of PCBs required to recover DCBs in which errors have occurred from the base station.

The terminal can obtain the number of additional PCBs based on at least one of information about the size of the CB included in the DCI received in step S3110, information about the length of the CRC (Cyclic Redundancy Check) of the CB, or information about the number of coded bits included in the DCI received in step S3150. Here, the number of coded bits can be determined based on at least one of information about the number of radio resources included in the DCI received in step S3150, information about the modulation order, information about the code rate, or information about the number of layers.

The terminal can obtain an index of an additional PCB based on the number of PCBs included in the CB received in step S3120, the number of additional PCBs, and a second table. The second table can include information about the number of PCBs for recovering DCBs in which errors occurred, information about the number of bits of HARQ-ACK feedback, information about the number of additional PCBs, and information about the start index of the additional PCB. The terminal can perform recovery for DCBs in which errors occurred based on the additional PCBs.

If the CB is not the initially transmitted CB (NO of S3130), the terminal may transmit a HARQ-ACK feedback requesting retransmission of the initially transmitted CB to the base station (S3160). The terminal may store the PCB included in the CB received in S3120. The terminal may generate the HARQ-ACK feedback requesting retransmission of the initially transmitted CB. The terminal may generate the HARQ-ACK feedback based on the first table. The terminal may transmit the HARQ-ACK feedback to the base station.

The terminal can receive the CB initially transmitted from the base station (S3170). The terminal can receive DCI including first information and information about the size of the CB from the base station through a first channel. The terminal can receive the CB initially transmitted including a plurality of DCBs (data code blocks) and a second PCB from the base station through a second channel.

In addition, the terminal can determine whether there are DCBs with errors among the multiple DCBs included in the initially transmitted CB. If there are DCBs with errors among the multiple DCBs, the terminal can obtain the number of PCBs required to recover the DCBs with errors based on the number of PCBs included in the CB received from S3120 and the number of PCBs without errors among the PCBs included in the initially transmitted CB.

In this case, the terminal can obtain the number of PCBs included in the CB received in S3120 based on at least one of information about the size of the CB included in the DCI received in step S3170, information about the length of the CRC (Cyclic Redundancy Check) of the CB, or information about the number of coded bits. Here, the number of coded bits can be determined based on at least one of the number of radio resources, the modulation order, the code rate, or the number of layers. The terminal can generate an HARQ-ACK requesting an additional PCB based on the number of PCBs required to repair DCBs in which errors occur. The terminal can transmit the HARQ-ACK to the base station. The terminal can receive additional PCBs greater than the number of PCBs required to repair DCBs in which errors occur from the base station. The terminal can perform repair for the DCBs in which errors occur based on the received PCBs.

FIG. 32 is a flowchart of a signal transmission and reception method according to another embodiment of the present disclosure.

In FIG. 32, the method may further include a step of the base station transmitting one or more synchronization signals to the terminal before step S3210 of FIG. 32, and a step of the base station transmitting control information to the terminal.

Referring to FIG. 32, the base station can transmit DCI to the terminal (S3210). The base station can transmit DCI to the terminal through the first channel. The first channel can be a PDCCH.

The base station can transmit a CB to the terminal (S3220). The base station can transmit the CB to the terminal through a second channel. The second channel can be a PDSCH. If the base station initially transmits the CB, the CB can include a plurality of DCBs and at least one PCB. If the base station does not initially transmit the CB, the CB can include at least one PCB.

The base station can receive HARQ-ACK feedback from the terminal (S3230). The HARQ-ACK feedback can include information about retransmission of the initially transmitted CB or a request for additional PCB transmission. For example, the HARQ-ACK feedback can be generated based on a preset table such as Table 9 or 10.

The base station can retransmit the initially transmitted CB to the terminal or transmit an additional PCB to the terminal based on the HARQ-ACK feedback (S3240). If the HARQ-ACK feedback received in S3230 includes information regarding a request for retransmission of the initially transmitted CB, the base station can transmit the initially transmitted CB to the terminal. In this case, the base station can retransmit the initially transmitted CB to the terminal through a different redundancy version than the initially transmitted redundancy version.

If the HARQ-ACK feedback received from S3230 includes information regarding a request for transmission of additional PCBs, the base station may transmit additional PCBs to the terminal. The base station may transmit additional PCBs to the terminal more than the number of PCBs requested for transmission.

In one embodiment, the base station can determine the number of additional PCBs based on a first table (e.g., Table 9 or 10) that includes information about a number of requested PCBs for transmission, information about a number of bits of HARQ-ACK feedback, and information about a number of additional PCBs. The information about the number of requested PCBs for transmission and the information about the number of additional PCBs included in the first table can be determined based on a number of a plurality of DCBs included in the first CB and a probability distribution of the additional PCBs according to the number of the plurality of DCBs.

The base station can determine an index of an additional PCB based on a second table including information about the number of PCBs included in the first CB, the number of additional PCBs, the number of requested PCBs to be transmitted, information about the number of bits of HARQ-ACK feedback, information about the number of additional PCBs, and information about a start index of the additional PCB.

The embodiments described above are combinations of the components and features of the present specification in a given form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, it is also possible to combine some components and/or features to form an embodiment of the present specification. The order of the operations described in the embodiments of the present specification may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment. It is obvious that claims that do not have an explicit citation relationship in the scope of the patent may be combined to form an embodiment or may be included as a new claim by post-application amendment.

Embodiments according to the present specification may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In case of hardware implementation, an embodiment of the present invention may be implemented by one or more ASICs (application specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, an embodiment of the present specification may be implemented in the form of a module, procedure, function, etc. that performs the functions or operations described above. The software code may be stored in a memory and may be driven by a processor. The memory may be located inside or outside the processor and may exchange data with the processor by various means already known.

It will be apparent to those skilled in the art that this specification may be embodied in other specific forms without departing from the essential characteristics of this specification. Accordingly, the above detailed description should not be construed in all respects as restrictive but as illustrative. The scope of this specification should be determined by a reasonable interpretation of the appended claims, and all changes within the equivalency range of this specification are intended to be included in the scope of this specification.

Claims (17)

In a method performed by a user equipment (UE) in a wireless communication system, A step of receiving one or more synchronization signals from a base station (BS); A step of receiving control information from the base station; A step of receiving a first DCI (downlink control information) including first information from the base station through a first channel; A step of receiving a first CB (Code block) from the base station through a second channel; A step of determining whether the first CB is the first transmission from the base station based on the first information; and A method comprising the step of transmitting a first HARQ-ACK (Hybrid Automatic Repeat reQuest Acknowledgement) feedback to the base station based on whether the first CB is transmitted initially. In the first paragraph, The step of transmitting a first HARQ-ACK feedback to the base station based on whether the first CB is the first transmitted from the base station is, If it is determined that the above 1st CB is not the first transmission, A step of storing a first PCB included in the first CB; A step of generating a first HARQ-ACK feedback requesting retransmission of the initially transmitted second CB; A step of transmitting the first HARQ-ACK feedback to the base station; A step of receiving a second DCI including the first information and information about the size of the second CB from the base station through the first channel; and A method further comprising the step of receiving, from the base station, a second CB including a plurality of DCBs (data code blocks) and a second PCB through the second channel. In the second paragraph, A step of determining whether there are DCBs among the plurality of DCBs included in the second CB that have errors; A step of determining the number of the first PCB; A step of determining the number of third PCBs for repairing the DCBs in which errors occurred, based on the number of PCBs in which errors did not occur among the first PCB and the second PCB, when there are DCBs in which errors occurred among the plurality of DCBs; A step of generating a second HARQ-ACK feedback based on the number of the third PCB and the preset table; a step of transmitting the second HARQ-ACK feedback to the base station; and A method further comprising the step of receiving a fourth PCB greater than the number of the third PCBs from the base station. In the third paragraph, The step of determining the number of the first PCB is: A step of determining the number of the first PCBs based on at least one of information about the size of the second CB included in the second DCI, information about the length of a CRC (Cyclic Redundancy Check) of the second CB, or information about the number of coded bits included in the first DCI, A method wherein the number of coded bits is determined based on at least one of information regarding the number of wireless resources included in the first DCI, information regarding a modulation order, information regarding a code rate, or information regarding the number of layers. In the first paragraph, The step of transmitting the first HARQ-ACK feedback to the above base station based on whether the first CB is transmitted for the first time is as follows: If the above 1st CB is judged to be the first transmission, A step of determining whether there are DCBs among the plurality of DCBs included in the first CB that have errors; A step of obtaining the number of fifth PCBs for recovering the DCBs in which errors have occurred, based on the number of first PCBs in which errors have not occurred among the first PCBs included in the first CB, when there are DCBs in which errors have occurred among the plurality of DCBs; A step of generating the first HARQ-ACK feedback based on the number of the fifth PCB; A step of transmitting the first HARQ-ACK feedback to the base station; A step of receiving a third DCI including at least one of information about the number of wireless resources of the first information and the second channel, information about a modulation order, information about a code rate, or information about the number of layers from the base station through the first channel; and A method further comprising the step of receiving a sixth PCB, which is greater than the number of the fifth PCB, from the base station through the second channel. In paragraph 5, The step of generating the first HARQ-ACK feedback based on the number of the fifth PCB is as follows: A step of receiving a first table including information about the number of the fifth PCB, information about the number of bits of the first HARQ-ACK feedback, and information about the number of the sixth PCB from the base station, or information necessary to generate the first table; A step of generating the first HARQ-ACK feedback based on the number of the fifth PCB and the first table, A method wherein information about the number of the fifth PCB included in the first table and information about the number of the sixth PCB are determined based on the number of the plurality of DCBs included in the first CB and the probability distribution of the fifth PCB according to the number of the plurality of DCBs. In paragraph 5, The number of the above 6th PCB is, It is determined based on at least one of information about the size of the first CB included in the first DCI, information about the length of the CRC (Cyclic Redundancy Check) of the first CB, or information about the number of coded bits included in the third DCI, A method wherein the number of coded bits is determined based on at least one of information regarding the number of wireless resources included in the third DCI, information regarding a modulation order, information regarding a code rate, or information regarding the number of layers. In paragraph 5, The index of the above 6th PCB is, A method determined based on a second table including information about the number of the first PCB, the number of the sixth PCB, and the number of the fifth PCB, information about the number of bits of the first HARQ-ACK feedback, information about the number of the sixth PCB, and information about the start index of the sixth PCB. In a terminal (user equipment, UE) operating in a communication system, One or more transmitters and receivers; one or more processors controlling said one or more transceivers; and A memory comprising one or more instructions to be performed by said one or more processors, One or more of the above commands, A step of receiving one or more synchronization signals from a base station (BS); A step of receiving control information from the base station; A step of receiving a first DCI (downlink control information) including first information from the base station through a first channel; A step of receiving a first CB (Code block) from the base station through a second channel; A step of determining whether the first CB is the first transmission from the base station based on the first information; and A terminal comprising a step of transmitting a first HARQ-ACK (Hybrid Automatic Repeat reQuest Acknowledgement) feedback to the base station based on whether the first CB is transmitted initially. In a method performed by a base station (BS) in a wireless communication system, A step of transmitting one or more synchronization signals to a user equipment (UE); A step of transmitting control information to the above terminal; A step of transmitting DCI (downlink control information) to the terminal through a first channel; A step of transmitting a first CB (Code block) to the above terminal through a second channel; A step of receiving HARQ-ACK (Hybrid Automatic Repeat reQuest Acknowledgement) feedback from the terminal; and A method comprising the step of retransmitting, to the terminal, a second CB initially transmitted to the terminal or transmitting an additional PCB based on the HARQ-ACK feedback. In Article 10, The step of retransmitting the second CB initially transmitted to the terminal or transmitting an additional PCB based on the HARQ-ACK feedback to the terminal is as follows. If the above HARQ-ACK feedback includes information regarding a retransmission request of the second CB, A method comprising the step of retransmitting the second CB to the terminal through a redundancy version (Redundancy Version, RV) different from the redundancy version of the initial transmission. In Article 10, The step of retransmitting the second CB initially transmitted to the terminal or transmitting an additional PCB based on the HARQ-ACK feedback to the terminal is as follows. If the above HARQ-ACK feedback contains information regarding an additional PCB transmission request, A method comprising the step of transmitting additional PCBs greater than the number of PCBs requested for transmission to the terminal. In Article 12, The number of additional PCBs above is, It is determined based on a first table including information about the number of the requested transmission PCBs, information about the number of bits of the HARQ-ACK feedback, and information about the number of the additional PCBs, A method wherein information about the number of the requested PCBs for transmission included in the first table and information about the number of the additional PCBs are determined based on the number of a plurality of DCBs included in the first CB and a probability distribution of the additional PCBs according to the number of the plurality of DCBs. In Article 12, The index of the above additional PCB is, A method determined based on a second table including information about the number of PCBs included in the first CB, the number of additional PCBs, and the number of requested PCBs for transmission, information about the number of bits of the HARQ-ACK feedback, information about the number of additional PCBs, and information about the start index of the additional PCB. In a base station (BS) operating in a communication system, One or more transmitters and receivers; one or more processors controlling said one or more transceivers; and A memory comprising one or more instructions to be performed by said one or more processors, One or more of the above commands, A step of transmitting one or more synchronization signals to a user equipment (UE); A step of transmitting control information to the above terminal; A step of transmitting DCI (downlink control information) to the terminal through a first channel; A step of transmitting a first CB (Code block) to the above terminal through a second channel; A step of receiving HARQ-ACK (Hybrid Automatic Repeat reQuest Acknowledgement) feedback from the terminal; and A base station comprising a step of retransmitting, to the terminal, a second CB initially transmitted to the terminal or transmitting a first PCB based on the HARQ-ACK feedback. In a device comprising one or more memories and one or more processors functionally connected to the one or more memories, The above one or more processors are configured such that the device, Receive at least one synchronization signal from a base station (BS), Receive control information from the above base station, Receive first DCI (downlink control information) including first information from the base station through the first channel, Receive the first CB (Code block) from the above base station through the second channel, Based on the above first information, it is determined whether the first CB is the first transmission from the base station, and, A device operative to transmit a first HARQ-ACK (Hybrid Automatic Repeat reQuest Acknowledgement) feedback to the base station based on whether the first CB is transmitted initially. In one or more non-transitory computer-readable media storing one or more instructions, Receive at least one synchronization signal from a base station (BS), Receive control information from the above base station, Receive first DCI (downlink control information) including first information from the base station through the first channel, Receive the first CB (Code block) from the above base station through the second channel, Based on the above first information, it is determined whether the first CB is the first transmission from the base station, and, A computer-readable medium operable to transmit, to the base station, a first HARQ-ACK (Hybrid Automatic Repeat reQuest Acknowledgement) feedback based on whether the first CB is transmitted initially.

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