WO2022250221A1

WO2022250221A1 - Method and device for transmitting signal in wireless communication system

Info

Publication number: WO2022250221A1
Application number: PCT/KR2021/016441
Authority: WO
Inventors: 최준일; 홍성혁; 박재용; 김성진
Original assignee: 엘지전자 주식회사; 한국과학기술원
Priority date: 2021-05-25
Filing date: 2021-11-11
Publication date: 2022-12-01
Also published as: KR20240011153A

Abstract

As one embodiment of the present disclosure, a method for operating a terminal in a wireless communication system comprises steps in which: a terminal receives a channel status information-reference signal (CSI-RS) from a base station; feedback is transmitted on the basis of the received CSI-RS; and an intelligent reflecting surface (IRS) reflection matrix is set on the basis of the received CSI-RS. The CSI-RS can be transmitted through an IRS. In addition, the method comprises the steps of: setting a precoder and a combiner on the basis of the received CSI-RS; determining beamforming on the basis of the set precoder and combiner; and receiving a signal from the base station through the IRS on the basis of the determined beamforming.

Description

Signal transmission method and apparatus in wireless communication system

The following description relates to a wireless communication system, and relates to an apparatus and method for channel estimation in a wireless communication system.

A wireless access system is widely deployed to provide various types of communication services such as voice and data. In general, a wireless access system is a multiple access system capable of supporting communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of the multiple access system include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, and a single carrier frequency (SC-FDMA) system. division multiple access) system.

In particular, as many communication devices require large communication capacity, an enhanced mobile broadband (eMBB) communication technology compared to existing radio access technology (RAT) has been proposed. In addition, a communication system considering reliability and latency-sensitive services/UE (user equipment) as well as mMTC (massive machine type communications) providing various services anytime and anywhere by connecting multiple devices and objects has been proposed. . Various technical configurations for this have been proposed.

The present disclosure may provide an apparatus and method for channel estimation in a wireless communication system.

The present disclosure may provide an apparatus and method for channel estimation in a wireless communication system including an intelligent reflecting surface (IRS).

The technical objects to be achieved in the present disclosure are not limited to the above-mentioned matters, and other technical problems not mentioned above are common knowledge in the art to which the technical configuration of the present disclosure is applied from the embodiments of the present disclosure to be described below. can be considered by those who have

As an example of the present disclosure, a method of operating a terminal in a wireless communication system includes receiving a channel status information-reference signal (CSI-RS) by the terminal from a base station, and transmitting feedback based on the received CSI-RS. and setting an intelligent reflecting surface (IRS) reflection matrix based on the received CSI-RS. The CSI-RS may be transmitted through an IRS. In addition, the operating method of the terminal includes setting a precoder and a combiner based on the received CSI-RS, determining beamforming based on the set precoder and combiner, and based on the determined beamforming and receiving a signal from the base station through the IRS. The terminal may be based on time division duplexing (TDD). Configuration information related to the procoder and the combiner may be transmitted to the base station. The terminal may be based on frequency division duplexing (FDD). The precoder may include an analog precoder based on the CSI-RS. The combiner may include an analog combiner based on the CSI-RS. The precoder may include a baseband precoder based on a power allocation matrix. The combiner may include a baseband combiner based on an effective channel of a subcarrier. The analog precoder and the analog combiner may be based on a matrix multiplication operation.

As an embodiment of the present disclosure, in a wireless communication system, a terminal includes a transceiver and a processor connected to the transceiver. The processor may control the transceiver to receive a channel status information-reference signal (CSI-RS) from the base station. The processor may control the transceiver to transmit feedback based on the received CSI-RS. The processor may set an intelligent reflecting surface (IRS) reflection matrix based on the received CSI-RS. The CSI-RS may be transmitted through an IRS. The processor may set a precoder and a combiner based on the received CSI-RS. The processor may determine beamforming based on the set precoder and combiner. The processor may control the transceiver to receive a signal from the base station through the IRS based on the determined beamforming. The terminal may be based on time division duplexing (TDD). The processor may control the transceiver to transmit configuration information related to the procoder and the combiner to the base station. The terminal may be based on frequency division duplexing (FDD). The precoder includes an analog precoder based on the CSI-RS. The combiner includes an analog combiner based on the CSI-RS. The precoder includes a baseband precoder based on a power allocation matrix. The combiner includes a baseband combiner based on an effective channel of a subcarrier. The analog precoder and the analog combiner may be based on a matrix multiplication operation.

As an embodiment of the present disclosure, a communication device includes at least one processor and at least one computer memory connected to the at least one processor and storing instructions that instruct operations as executed by the at least one processor. do. The processor may control the communication device to receive a channel status information-reference signal (CSI-RS) from a base station. The processor may control the communication device to transmit feedback based on the received CSI-RS. The processor may control the communication device to set an IRS reflection matrix based on the received CSI-RS. The CSI-RS may be transmitted through an IRS reflection matrix. The processor may control the communication device to set a precoder and a combiner based on the received CSI-RS. The processor may control the communication device to determine beamforming based on the set precoder and combiner. The processor may control the communication device to receive a signal from the base station through the IRS based on the determined beamforming.

As an embodiment of the present disclosure, a non-transitory computer-readable medium storing at least one instruction (instructions) may include the at least one instruction executable by a processor. includes The at least one instruction may instruct the computer readable medium to receive a channel status information-reference signal (CSI-RS) from a base station. The at least one instruction may instruct the computer readable medium to transmit feedback based on the received CSI-RS. The at least one instruction may instruct the computer readable medium to set an IRS reflection matrix based on the received CSI-RS. The CSI-RS may be transmitted through an IRS reflection matrix. The at least one command may instruct the computer readable medium to set a precoder and a combiner based on the received CSI-RS. The at least one instruction may instruct the computer readable medium to determine beamforming based on the set precoder and combiner. The at least one instruction may instruct the computer readable medium to receive a signal from the base station through the IRS based on the determined beamforming.

As an embodiment of the present disclosure, a method of operating a base station in a wireless communication system includes transmitting a channel status information-reference signal (CSI-RS) to a terminal, and receiving configuration information related to a precoder and a combiner from the terminal. Step, setting a precoder and a combiner based on the setting information, determining transmission beamforming based on the set precoder and combiner, and providing the terminal with an IRS based on the determined transmission beamforming ( and transmitting a signal through an intelligent reflecting surface. The configuration information is information on a precoder and a combiner configured by the terminal based on the CSI-RS. The CSI-RS is transmitted through IRS.

As an embodiment of the present disclosure, a base station in a wireless communication system includes a transceiver and a processor connected to the transceiver. The processor may control the transceiver to transmit a channel status information-reference signal (CSI-RS) to the terminal. The processor may control the transceiver to receive setting information related to a precoder and a combiner from the terminal. The processor may set a precoder and a combiner based on the setting information. Tx beamforming may be determined based on the set precoder and combiner. Based on the determined transmit beamforming, control may be performed to transmit a signal to the terminal through an intelligent reflecting surface (IRS). The configuration information is information on a precoder and a combiner configured by the terminal based on the CSI-RS. The CSI-RS may be transmitted through an IRS.

The above-described aspects of the present disclosure are only some of the preferred embodiments of the present disclosure, and various embodiments in which the technical features of the present disclosure are reflected are detailed descriptions of the present disclosure to be detailed below by those of ordinary skill in the art. It can be derived and understood based on.

The following effects may be obtained by embodiments based on the present disclosure.

According to the present disclosure, channel estimation may be performed in a wireless communication system that includes an intelligent reflecting surface (IRS).

According to the present disclosure, overhead of channel estimation may be reduced based on a training sequence proportional to an IRS scale.

According to the present disclosure, efficient beamforming can be performed in a massive MIMO (massive multi input multi output) environment.

According to the present disclosure, a hybrid beamformer can achieve spectral efficiency of a fully-digital beamformer.

Effects obtainable in the embodiments of the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned are technical fields to which the technical configuration of the present disclosure is applied from the description of the following embodiments of the present disclosure. can be clearly derived and understood by those skilled in the art. That is, unintended effects according to implementing the configuration described in the present disclosure may also be derived by those skilled in the art from the embodiments of the present disclosure.

The accompanying drawings are provided to aid understanding of the present disclosure, and may provide embodiments of the present disclosure together with a detailed description. However, the technical features of the present disclosure are not limited to specific drawings, and features disclosed in each drawing may be combined with each other to form a new embodiment. Reference numerals in each drawing may mean structural elements.

1 is a diagram illustrating an example of a communication system applicable to the present disclosure.

2 is a diagram illustrating an example of a wireless device applicable to the present disclosure.

3 is a diagram illustrating another example of a wireless device applicable to the present disclosure.

4 is a diagram illustrating an example of a portable device applicable to the present disclosure.

5 is a diagram illustrating an example of a vehicle or autonomous vehicle applicable to the present disclosure.

6 is a diagram showing an example of AI (Artificial Intelligence) applicable to the present disclosure.

7 is a diagram illustrating a method of processing a transmission signal applicable to the present disclosure.

8 is a diagram showing an example of a communication structure that can be provided in a 6G system applicable to the present disclosure.

9 is a diagram showing an electromagnetic spectrum applicable to the present disclosure.

10 is a diagram illustrating a THz communication method applicable to the present disclosure.

11 is a diagram illustrating an example of a wireless communication system including an IRS applicable to the present disclosure.

12 is a diagram illustrating an example of a hybrid beamformer applicable to the present disclosure.

13a and 13b show results according to an embodiment of the present disclosure.

14 illustrates an example of a terminal operating procedure applicable to the present disclosure.

15 illustrates an example of a base station operating procedure applicable to the present disclosure.

The following embodiments are those that combine elements and features of the present disclosure in a predetermined form. Each component or feature may be considered optional unless explicitly stated otherwise. Each component or feature may be implemented in a form not combined with other components or features. In addition, an embodiment of the present disclosure may be configured by combining some elements and/or features. The order of operations described in the embodiments of the present disclosure 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 disclosure have not been described, and procedures or steps that can be understood by those skilled in the art have not been described.

Throughout the specification, when a part is said to "comprising" or "including" a certain element, it means that it may further include other elements, not excluding other elements, unless otherwise stated. do. In addition, terms such as “… unit”, “… unit”, and “module” described in the specification mean a unit that processes at least one function or operation, which is hardware or software or a combination of hardware and software. can be implemented as Also, "a or an", "one", "the" and similar related words in the context of describing the present disclosure (particularly in the context of the claims below) Unless indicated or otherwise clearly contradicted by context, both the singular and the plural can be used.

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

That is, in a network composed 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 network nodes other than the base station. At this time, the 'base station' is a term such as a fixed station, Node B, eNode B, gNode B, ng-eNB, advanced base station (ABS), or access point. can be replaced by

In addition, in the embodiments of the present disclosure, a terminal includes a user equipment (UE), a mobile station (MS), a subscriber station (SS), a mobile subscriber station (MSS), It may be replaced with terms such as mobile terminal or advanced mobile station (AMS).

In addition, the transmitting end refers to a fixed and/or mobile node providing data service or voice service, and the receiving end refers to a fixed and/or mobile node receiving data service or voice service. Therefore, in the case of uplink, the mobile station can be a transmitter and the base station can be a receiver. Similarly, in the case of downlink, the mobile station may be a receiving end and the base station may be a transmitting end.

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

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

That is, obvious steps or parts not described in the embodiments of the present disclosure may be described with reference to the above documents. In addition, all terms disclosed in this document can be explained by the standard document.

Hereinafter, preferred embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description set forth below in conjunction with the accompanying drawings is intended to describe exemplary embodiments of the present disclosure, and is not intended to represent the only embodiments in which the technical configurations of the present disclosure may be practiced.

In addition, specific terms used in the embodiments of the present disclosure are provided to aid understanding of the present disclosure, and the use of these specific terms may be changed in other forms without departing from the technical spirit of the present disclosure.

The following technologies include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be applied to various wireless access systems.

In the following, in order to clarify the following description, the description is based on the 3GPP communication system (e.g. (eg, LTE, NR, etc.), but the technical spirit of the present invention is not limited thereto. LTE is 3GPP TS 36.xxx Release 8 or later In detail, LTE technology after 3GPP TS 36.xxx Release 10 is 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 mean technology after TS 38.xxx Release 15. 3GPP 6G may mean technology after TS Release 17 and/or Release 18. "xxx" means a standard document detail number. LTE/NR/6G may be collectively referred to as a 3GPP system.

For background art, terms, abbreviations, etc. used in the present disclosure, reference may be made to matters described in standard documents published prior to the present invention. As an example, 36.xxx and 38.xxx standard documents may be referred to.

본 개시에 적용 가능한 통신 시스템Communication systems applicable to the present disclosure

Although not limited thereto, various descriptions, functions, procedures, proposals, methods and / or operational flowcharts of the present disclosure disclosed in this document may be applied to various fields requiring wireless communication / connection (eg, 5G) between devices. have.

Hereinafter, it will be exemplified in more detail with reference to the drawings. In the following drawings/description, the same reference numerals may represent the same or corresponding hardware blocks, software blocks or functional blocks unless otherwise specified.

1 is a diagram illustrating an example of a communication system applied to the present disclosure.

Referring to FIG. 1 , a communication system 100 applied to the present disclosure includes a wireless device, a base station, and a network. Here, the wireless device means a device that performs communication using a radio access technology (eg, 5G NR, LTE), and may be referred to as a communication/wireless/5G device. Although not limited thereto, the wireless device includes a robot 100a, a vehicle 100b-1 and 100b-2, an extended reality (XR) device 100c, a hand-held device 100d, and a home appliance. appliance) 100e, Internet of Thing (IoT) device 100f, and artificial intelligence (AI) 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 inter-vehicle communication, and the like. Here, the vehicles 100b-1 and 100b-2 may include an unmanned aerial vehicle (UAV) (eg, a drone). The XR device 100c includes augmented reality (AR)/virtual reality (VR)/mixed reality (MR) devices, and includes a head-mounted device (HMD), a head-up display (HUD) installed in a vehicle, a television, It may be implemented in the form of smart phones, computers, wearable devices, home appliances, digital signage, vehicles, robots, and the like. The mobile device 100d may include a smart phone, a smart pad, a wearable device (eg, a smart watch, a smart glass), a computer (eg, a laptop computer), and the like. The home appliance 100e may include a TV, a refrigerator, a washing machine, and the like. The IoT device 100f may include a sensor, a smart meter, and the like. For example, the base station 120 and the network 130 may also be implemented as a wireless device, and a specific wireless device 120a may operate as a base station/network node to other wireless devices.

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

Wireless communication/

connection

150a, 150b, and 150c may be performed between the wireless devices 100a to 100f/base station 120 and the base station 120/base station 120. Here, wireless communication/connection includes various types of uplink/downlink communication 150a, sidelink communication 150b (or D2D communication), and inter-base station communication 150c (eg relay, integrated access backhaul (IAB)). This can be done through radio access technology (eg 5G NR). Through the wireless communication/

connection

150a, 150b, and 150c, a wireless device and a base station/wireless device, and a base station and a base station can transmit/receive radio signals to each other. For example, the wireless communication/

connections

150a, 150b, and 150c may transmit/receive signals through various physical channels. To this end, based on various proposals of the present disclosure, various configuration information setting processes for transmitting / receiving radio signals, various signal processing processes (eg, channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.) At least a part of a resource allocation process may be performed.

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

The first wireless device 200a includes one or more processors 202a and one or more memories 204a, and may further 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 flow diagrams disclosed herein. For example, the processor 202a may process information in the memory 204a to generate first information/signal, and transmit a radio signal including the first information/signal through the transceiver 206a. In addition, the processor 202a may receive a radio signal including the second information/signal through the transceiver 206a and 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, memory 204a may perform some or all of the processes controlled by processor 202a, or instructions for performing the descriptions, functions, procedures, suggestions, methods, and/or flowcharts of operations disclosed herein. It may store software codes including them. Here, the processor 202a and the memory 204a may be part of a communication modem/circuit/chip designed to implement a wireless communication technology (eg, LTE, NR). The transceiver 206a may be coupled to the processor 202a and may transmit and/or receive wireless signals through one or more antennas 208a. The transceiver 206a may include a transmitter and/or a receiver. The transceiver 206a may be used interchangeably with a radio frequency (RF) unit. In the present disclosure, a wireless device may mean a communication modem/circuit/chip.

The second wireless device 200b includes one or more processors 202b, one or more memories 204b, and may further include one or more transceivers 206b and/or one or more antennas 208b. The processor 202b controls the memory 204b and/or the transceiver 206b and may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or operational flow diagrams disclosed herein. For example, the processor 202b may process information in the memory 204b to generate third information/signal, and transmit a radio signal including the third information/signal through the transceiver 206b. In addition, the processor 202b may receive a radio signal including the fourth information/signal through the transceiver 206b and 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 instructions for performing the descriptions, functions, procedures, suggestions, methods, and/or flowcharts of operations disclosed herein. It may store software codes including them. Here, the processor 202b and the memory 204b may be part of a communication modem/circuit/chip designed to implement a wireless communication technology (eg, LTE, NR). The transceiver 206b may be coupled to the processor 202b and may transmit and/or receive wireless signals through 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 the present disclosure, a wireless device may mean a communication modem/circuit/chip.

Hereinafter, hardware elements of the

wireless devices

200a and 200b will be described in more detail. Although not limited to this, one or more protocol layers may be implemented by one or

more processors

202a, 202b. For example, the one or

more processors

202a and 202b may include one or more layers (eg, PHY (physical), MAC (media access control), RLC (radio link control), PDCP (packet data convergence protocol), RRC (radio resource) control) and functional layers such as 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 flow charts disclosed herein. can create 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 flow diagrams disclosed herein. One or

more processors

202a, 202b generate PDUs, SDUs, messages, control information, data or signals (eg, baseband signals) containing information according to the functions, procedures, proposals and/or methods disclosed herein , may be provided to one or

more transceivers

206a and 206b. One or

more processors

202a, 202b may receive signals (eg, baseband signals) from one or

more transceivers

206a, 206b, and descriptions, functions, procedures, suggestions, methods, and/or flowcharts of operations disclosed herein PDUs, SDUs, messages, control information, data or information can be obtained according to these.

One or

more processors

202a, 202b may be referred to as a controller, microcontroller, microprocessor or microcomputer. 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 one or

more processors

202a and 202b. The descriptions, functions, procedures, proposals, methods and/or operational flowcharts disclosed in this document may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, and the like. Firmware or software configured to perform the descriptions, functions, procedures, proposals, methods and/or operational flow charts disclosed in this document may be included in one or

more processors

202a or 202b or stored in one or

more memories

204a or 204b. It can be driven by the

above processors

202a and 202b. The descriptions, functions, procedures, suggestions, methods and/or operational flow charts disclosed in this document 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 types of data, signals, messages, information, programs, codes, instructions and/or instructions. One or

more memories

204a, 204b may include read only memory (ROM), random access memory (RAM), erasable programmable read only memory (EPROM), flash memory, hard drive, registers, cache memory, computer readable storage media, and/or It may consist of a combination of these. One or

more memories

204a, 204b may be located internally and/or externally to one or

more processors

202a, 202b. In addition, one or

more memories

204a, 204b may be connected to one or

more processors

202a, 202b through various technologies such as wired or wireless connections.

One or

more transceivers

206a, 206b may transmit user data, control information, radio signals/channels, etc. referred to in the methods and/or operational flow charts of this document to one or more other devices. One or

more transceivers

206a, 206b may receive user data, control information, radio signals/channels, etc. referred to in descriptions, functions, procedures, proposals, methods and/or operational flow charts, etc. disclosed herein from one or more other devices. have. For example, one or

more transceivers

206a and 206b may be connected to one or

more processors

202a and 202b and transmit and receive radio signals. For example, one or

more processors

202a, 202b may control one or

more transceivers

206a, 206b to transmit user data, control information, or radio signals to one or more other devices. In addition, one or

more processors

202a, 202b may control one or

more transceivers

206a, 206b to receive user data, control information, or radio signals from one or more other devices. In addition, 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 connected to one or

more antennas

208a, 208b to achieve the descriptions, functions disclosed in this document. , procedures, proposals, methods and / or operation flowcharts, etc. can be set to transmit and receive user data, control information, radio signals / channels, etc. In this document, one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (eg, antenna ports). One or more transceivers (206a, 206b) in order to process the received user data, control information, radio signal / channel, etc. using one or more processors (202a, 202b), the received radio signal / channel, etc. in the RF band signal It can be converted into a baseband signal. One or

more transceivers

206a and 206b may convert user data, control information, and radio signals/channels processed by one or

more processors

202a and 202b from baseband signals to RF band signals. To this end, one or

more transceivers

206a, 206b may include (analog) oscillators and/or filters.

본 개시에 적용 가능한 무선 기기 구조Wireless device structure applicable to the present disclosure

3 is a diagram illustrating another example of a wireless device applied to the present disclosure.

Referring to FIG. 3, a wireless device 300 corresponds to the

wireless devices

200a and 200b of FIG. 2, and includes various elements, components, units/units, and/or modules. ) can be configured. For example, the wireless device 300 may include a communication unit 310, a control unit 320, a memory unit 330, and an additional element 340. The communication unit may include communication circuitry 312 and transceiver(s) 314 . For example, communication circuitry 312 may include one or

more processors

202a, 202b of FIG. 2 and/or one or

more memories

204a, 204b. For example, transceiver(s) 314 may include one or

more transceivers

206a, 206b of FIG. 2 and/or one or

more antennas

208a, 208b. The control unit 320 is electrically connected to the communication unit 310, the memory unit 330, and the additional element 340 and controls overall operations of the wireless device. For example, the control unit 320 may control electrical/mechanical operations of the wireless device based on programs/codes/commands/information stored in the memory unit 330. In addition, the control unit 320 transmits the information stored in the memory unit 330 to the outside (eg, another communication device) through the communication unit 310 through a wireless/wired interface, or transmits the information stored in the memory unit 330 to the outside (eg, another communication device) through the communication unit 310. Information received through a wireless/wired interface from other communication devices) may be stored in the memory unit 330 .

The additional element 340 may be configured in various ways according to the type of wireless device. For example, the additional element 340 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 300 may be a robot (FIG. 1, 100a), a vehicle (FIG. 1, 100b-1, 100b-2), an XR device (FIG. 1, 100c), a mobile device (FIG. 1, 100d) ), home appliances (FIG. 1, 100e), IoT devices (FIG. 1, 100f), digital broadcasting terminals, hologram devices, public safety devices, MTC devices, medical devices, fintech devices (or financial devices), security devices, climate/ It may be implemented in the form of an environment device, an AI server/device (FIG. 1, 140), a base station (FIG. 1, 120), a network node, and the like. Wireless devices can be mobile or used in a fixed location depending on the use-case/service.

In FIG. 3 , various elements, components, units/units, and/or modules in the wireless device 300 may be entirely interconnected through a wired interface or at least partially connected wirelessly through the communication unit 310 . For example, in the wireless device 300, the control unit 320 and the communication unit 310 are connected by wire, and the control unit 320 and the first units (eg, 130 and 140) are connected wirelessly through the communication unit 310. can be connected Additionally, each element, component, unit/unit, and/or module within wireless device 300 may further include one or more elements. For example, the control unit 320 may be composed of one or more processor sets. For example, the control unit 320 may include a set of a communication control processor, an application processor, an electronic control unit (ECU), a graphic processing processor, a memory control processor, and the like. As another example, the memory unit 330 may include RAM, dynamic RAM (DRAM), ROM, flash memory, volatile memory, non-volatile memory, and/or combinations thereof. can be configured.

본 개시가 적용 가능한 휴대 기기Mobile device to which the present disclosure is applicable

4 is a diagram illustrating an example of a portable device applied to the present disclosure.

4 illustrates a portable device applied to the present disclosure. A portable device may include a smart phone, a smart pad, a wearable device (eg, smart watch, smart glasses), and a portable computer (eg, a laptop computer). A 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. 4 , a portable device 400 includes an antenna unit 408, a communication unit 410, a control unit 420, a memory unit 430, a power supply unit 440a, an interface unit 440b, and an input/output unit 440c. ) may be included. The antenna unit 408 may be configured as part of the communication unit 410 . Blocks 410 to 430/440a to 440c respectively correspond to blocks 310 to 330/340 of FIG. 3 .

The communication unit 410 may transmit/receive signals (eg, data, control signals, etc.) with other wireless devices and base stations. The controller 420 may perform various operations by controlling components of the portable device 400 . The controller 420 may include an application processor (AP). The memory unit 430 may store data/parameters/programs/codes/commands necessary for driving the portable device 400 . Also, the memory unit 430 may store input/output data/information. The power supply unit 440a supplies power to the portable device 400 and may include a wired/wireless charging circuit, a battery, and the like. The interface unit 440b may support connection between the mobile device 400 and other external devices. The interface unit 440b may include various ports (eg, audio input/output ports and video input/output ports) for connection with external devices. The input/output unit 440c may receive or output image information/signal, audio information/signal, data, and/or information input from a user. The input/output unit 440c may include a camera, a microphone, a user input unit, a display unit 440d, a speaker, and/or a haptic module.

For example, in the case of data communication, the input/output unit 440c acquires information/signals (eg, touch, text, voice, image, video) input from the user, and the acquired information/signals are stored in the memory unit 430. can be stored The communication unit 410 may convert the information/signal stored in the memory into a wireless signal, and directly transmit the converted wireless signal to another wireless device or to a base station. In addition, the communication unit 410 may receive a radio signal from another wireless device or base station and then restore the received radio signal to original information/signal. After the restored information/signal is stored in the memory unit 430, it may be output in various forms (eg, text, voice, image, video, or haptic) through the input/output unit 440c.

본 개시가 적용 가능한 무선 기기 종류Types of wireless devices to which this disclosure is applicable

5 is a diagram illustrating an example of a vehicle or autonomous vehicle to which the present disclosure applies.

5 illustrates a vehicle or autonomous vehicle to which the present disclosure is applied. A vehicle or an autonomous vehicle may be implemented as a mobile robot, vehicle, train, manned/unmanned aerial vehicle (AV), ship, etc., and is not limited to a vehicle type.

Referring to FIG. 5 , a vehicle or autonomous vehicle 500 includes an antenna unit 508, a communication unit 510, a control unit 520, a driving unit 540a, a power supply unit 540b, a sensor unit 540c, and an autonomous driving unit. A portion 540d may be included. The antenna unit 550 may be configured as a part of the communication unit 510 . Blocks 510/530/540a to 540d respectively correspond to blocks 410/430/440 of FIG. 4 .

The communication unit 510 may transmit/receive signals (eg, data, control signals, etc.) with external devices such as other vehicles, base stations (eg, base stations, roadside base units, etc.), servers, and the like. The controller 520 may perform various operations by controlling elements of the vehicle or autonomous vehicle 500 . The controller 520 may include an electronic control unit (ECU).

6 is a diagram illustrating an example of an AI device applied to the present disclosure. As an example, AI devices include TVs, projectors, smartphones, PCs, laptops, digital broadcasting terminals, tablet PCs, wearable devices, set-top boxes (STBs), radios, washing machines, refrigerators, digital signage, robots, vehicles, etc. It may be implemented as a device or a movable device.

Referring to FIG. 6, the AI device 600 includes a communication unit 610, a control unit 620, a memory unit 630, an input/output unit 640a/640b, a running processor unit 640c, and a sensor unit 640d. can include Blocks 610 to 630/640a to 640d may respectively correspond to blocks 310 to 330/340 of FIG. 3 .

The communication unit 610 communicates wired and wireless signals (eg, sensor information, user data) with external devices such as other AI devices (eg, FIG. 1, 100x, 120, and 140) or AI servers (Fig. input, learning model, control signal, etc.) can be transmitted and received. To this end, the communication unit 610 may transmit information in the memory unit 630 to an external device or transmit a signal received from the external device to the memory unit 630 .

The controller 620 may determine at least one executable operation of the AI device 600 based on information determined or generated using a data analysis algorithm or a machine learning algorithm. And, the controller 620 may perform the determined operation by controlling components of the AI device 600 . For example, the control unit 620 may request, retrieve, receive, or utilize data from the learning processor unit 640c or the memory unit 630, and may perform a predicted operation among at least one feasible operation or one determined to be desirable. Components of the AI device 600 may be controlled to execute an operation. In addition, the control unit 620 collects history information including user feedback on the operation contents or operation of the AI device 600 and stores it in the memory unit 630 or the running processor unit 640c, or the AI server ( 1, 140) can be transmitted to an external device. The collected history information can be used to update the learning model.

The memory unit 630 may store data supporting various functions of the AI device 600 . For example, the memory unit 630 may store data obtained from the input unit 640a, data obtained from the communication unit 610, output data of the learning processor unit 640c, and data obtained from the sensing unit 640. Also, the memory unit 630 may store control information and/or software codes required for operation/execution of the controller 620 .

The input unit 640a may obtain various types of data from the outside of the AI device 600. For example, the input unit 620 may obtain learning data for model learning and input data to which the learning model is to be applied. The input unit 640a may include a camera, a microphone, and/or a user input unit. The output unit 640b may generate an output related to sight, hearing, or touch. The output unit 640b may include a display unit, a speaker, and/or a haptic module. The sensing unit 640 may obtain at least one of internal information of the AI device 600, surrounding environment information of the AI device 600, and user information by using various sensors. The sensing unit 640 may include a proximity sensor, an illuminance sensor, an acceleration sensor, a magnetic sensor, a gyro sensor, an inertial sensor, an RGB sensor, an IR sensor, a fingerprint recognition sensor, an ultrasonic sensor, an optical sensor, a microphone, and/or a radar. have.

The learning processor unit 640c may learn a model composed of an artificial neural network using learning data. The running processor unit 640c may perform AI processing together with the running processor unit of the AI server (FIG. 1, 140). The learning processor unit 640c may process information received from an external device through the communication unit 610 and/or information stored in the memory unit 630 . In addition, the output value of the learning processor unit 640c may be transmitted to an external device through the communication unit 610 and/or stored in the memory unit 630.

7 is a diagram illustrating a method of processing a transmission signal applied to the present disclosure. For example, the transmitted signal may be processed by a signal processing circuit. In this case, the signal processing circuit 700 may include a scrambler 710, a modulator 720, a layer mapper 730, a precoder 740, a resource mapper 750, and a signal generator 760. At this time, as an example, the operation/function of FIG. 7 may be performed by the

processors

202a and 202b and/or the

transceivers

206a and 206b of FIG. 2 . Also, as an example, the hardware elements of FIG. 7 may be implemented in the

processors

202a and 202b and/or the

transceivers

206a and 206b of FIG. 2 . As an example, blocks 710 to 760 may be implemented in the

processors

202a and 202b of FIG. 2 . Also, blocks 710 to 750 may be implemented in the

processors

202a and 202b of FIG. 2 and block 760 may be implemented in the

transceivers

206a and 206b of FIG. 2 , and are not limited to the above-described embodiment.

The codeword may be converted into a radio signal through the signal processing circuit 700 of FIG. 7 . Here, a codeword is an encoded bit sequence of an information block. Information blocks may include transport blocks (eg, UL-SCH transport blocks, DL-SCH transport blocks). Radio signals may be transmitted through various physical channels (eg, PUSCH, PDSCH). Specifically, the codeword may be converted into a scrambled bit sequence by the scrambler 710. A scramble sequence used for scrambling is generated based on an initialization value, and the initialization value may include ID information of a wireless device. The scrambled bit sequence may be modulated into a modulation symbol sequence by modulator 720. The modulation method may include pi/2-binary phase shift keying (pi/2-BPSK), m-phase shift keying (m-PSK), m-quadrature amplitude modulation (m-QAM), and the like.

The complex modulation symbol sequence may be mapped to one or more transport layers by the layer mapper 730. Modulation symbols of each transport layer may be mapped to corresponding antenna port(s) by the precoder 740 (precoding). The output z of the precoder 740 can be obtained by multiplying the output y of the layer mapper 730 by the N*M precoding matrix W. Here, N is the number of antenna ports and M is the number of transport layers. Here, the precoder 740 may perform precoding after transform precoding (eg, discrete fourier transform (DFT)) on complex modulation symbols. Also, the precoder 740 may perform precoding without performing transform precoding.

The resource mapper 750 may map modulation symbols of each antenna port to time-frequency resources. The time-frequency resource may include a plurality of symbols (eg, CP-OFDMA symbols and DFT-s-OFDMA symbols) in the time domain and a plurality of subcarriers in the frequency domain. The signal generator 760 generates a radio signal from the mapped modulation symbols, and the generated radio signal can be transmitted to other devices through each antenna. To this end, the signal generator 760 may include an inverse fast fourier transform (IFFT) module, a cyclic prefix (CP) inserter, a digital-to-analog converter (DAC), a frequency uplink converter, and the like. .

The signal processing process for the received signal in the wireless device may be configured in reverse to the signal processing process 710 to 760 of FIG. 7 . For example, a wireless device (eg, 200a and 200b of FIG. 2 ) may receive a wireless signal from the outside through an antenna port/transceiver. The received radio signal may be converted into a baseband signal through a signal restorer. To this end, the signal restorer may 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 may be restored to a codeword through a resource de-mapper process, a postcoding process, a demodulation process, and a de-scramble process. The codeword may 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 demapper, a postcoder, a demodulator, a descrambler, and a decoder.

6G 통신 시스템 6G communication system

6G (radio communications) systems are characterized by (i) very high data rates per device, (ii) very large number of connected devices, (iii) global connectivity, (iv) very low latency, (v) battery- It aims to 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 four aspects such as "intelligent connectivity", "deep connectivity", "holographic connectivity", and "ubiquitous connectivity", and the 6G system can satisfy the requirements shown in Table 1 below. That is, Table 1 is a table showing the requirements of the 6G system.

Per device peak data ratePer device peak data rate	1 Tbps1 Tbps
E2E latencyE2E latency	1 ms1ms
Maximum spectral efficiencyMaximum spectral efficiency	100 bps/Hz100 bps/Hz
Mobility supportMobility support	up to 1000 km/hrup to 1000 km/hr
Satellite integrationSatellite integration	FullyFully
AIAI	FullyFully
Autonomous vehicleAutonomous vehicles	FullyFully
XRXR	FullyFully
Haptic CommunicationHaptic Communication	FullyFully

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

8 is a diagram illustrating an example of a communication structure that can be provided in a 6G system applicable to the present disclosure.

Referring to FIG. 8 , a 6G system is expected to have 50 times higher simultaneous wireless communication connectivity than a 5G wireless communication system. URLLC, a key feature of 5G, is expected to become a more mainstream technology by providing end-to-end latency of less than 1 ms in 6G communications. At this time, the 6G system will have much better volume spectral efficiency, unlike the frequently used area spectral efficiency. 6G systems can provide very long battery life and advanced battery technology for energy harvesting, so mobile devices in 6G systems may not need to be charged separately.

6G 시스템의 핵심 구현 기술Core implementation technology of 6G system

- 인공 지능(artificial Intelligence, AI)- Artificial Intelligence (AI)

The most important and newly introduced technology for the 6G system is AI. AI was not involved in the 4G system. 5G systems will support partial or very limited AI. However, the 6G system will be AI-enabled for full automation. Advances in machine learning will create more intelligent networks for real-time communication in 6G. Introducing AI in communications can simplify and enhance real-time data transmission. AI can use a plethora of analytics 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 by using AI. AI can also play an important role in machine-to-machine, machine-to-human and human-to-machine communications. In addition, AI can be a rapid communication in the 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 are focused on the application layer, network layer, and especially deep learning, wireless resource management and allocation. come. However, such research is gradually developing into the MAC layer and the physical layer, and in particular, attempts to combine deep learning with wireless transmission are appearing in the physical layer. AI-based physical layer transmission means applying a signal processing and communication mechanism based on an AI driver rather than a traditional communication framework in fundamental signal processing and communication mechanisms. For example, deep learning-based channel coding and decoding, deep learning-based signal estimation and detection, deep learning-based multiple input multiple output (MIMO) mechanism, It may include AI-based resource scheduling and allocation.

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

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

AI algorithms based on deep learning require a lot of training data to optimize training parameters. However, due to limitations in acquiring data in a specific channel environment as training data, a lot of training data is used offline. This is because static training on training data in a specific channel environment may cause a contradiction between dynamic characteristics and diversity of a radio 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 a wireless communication signal, further research is needed on a neural network that detects a complex domain signal.

Hereinafter, machine learning will be described in more detail.

Machine learning refers to a set of actions that train a machine to create a machine that can do tasks that humans can or cannot do. Machine learning requires data and a running model. In machine learning, data learning methods can be largely classified into three types: supervised learning, unsupervised learning, and reinforcement learning.

Neural network training is aimed at minimizing errors in the output. Neural network learning repeatedly inputs training data to the neural network, calculates the output of the neural network for the training data and the error of the target, and backpropagates the error of the neural network from the output layer of the neural network to the input layer in a direction to reduce the error. ) to update the weight of each node in the neural network.

Supervised learning uses training data in which correct answers are labeled in the learning data, and unsupervised learning may not have correct answers labeled in the learning data. That is, for example, learning data in the case of supervised learning related to data classification may be data in which each learning data is labeled with a category. Labeled training data is input to the neural network, and an error may be calculated by comparing the output (category) of the neural network and the label of the training data. The calculated error is back-propagated in a reverse direction (ie, from the output layer to the input layer) in the neural network, and the connection weight of each node of each layer of the neural network may be updated according to the back-propagation. The amount of change in the connection weight of each updated node may be determined according to a learning rate. The neural network's computation of input data and backpropagation of errors can constitute a learning cycle (epoch). The learning rate may be applied differently according to the number of iterations of the learning cycle of the neural network. For example, a high learning rate is used in the early stages of neural network learning to increase efficiency by allowing the neural network to quickly achieve a certain level of performance, and a low learning rate can be used in the late stage to increase accuracy.

The learning method may vary depending on the characteristics of the data. For example, in a case where the purpose of the receiver is to accurately predict data transmitted by the transmitter 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 considered. ) is called

The neural network cord used as a learning method is largely divided into deep neural networks (DNN), convolutional deep neural networks (CNN), and recurrent boltzmann machine (RNN). and this learning model can be applied.

THz(Terahertz) 통신Terahertz (THz) 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 using sub-THz communication with wide bandwidth and applying advanced massive MIMO technology.

9 is a diagram showing an electromagnetic spectrum applicable to the present disclosure. As an example, referring to FIG. 9 , THz waves, also known as sub-millimeter radiation, generally represent a frequency band between 0.1 THz and 10 THz with corresponding wavelengths in the range of 0.03 mm-3 mm. The 100 GHz-300 GHz band range (sub THz band) is considered a major part of the THz band for cellular communications. Adding to the sub-THz band mmWave band will increase 6G cellular communications capacity. Among the defined THz bands, 300 GHz-3 THz is in the far infrared (IR) frequency band. The 300 GHz-3 THz band is part of the broad band, but is at the border of the wide band, just behind the RF band. Thus, this 300 GHz-3 THz band exhibits similarities to RF.

The main 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 indispensable). The narrow beamwidth produced by the highly directional antenna reduces interference. The small wavelength of the THz signal allows a much larger number of antenna elements to be incorporated into devices and BSs operating in this band. This enables advanced adaptive array technology to overcome range limitations.

테라헤르츠(THz) 무선통신Terahertz (THz) wireless communication

Referring to FIG. 10, THz wireless communication uses wireless communication using a THz wave having a frequency of approximately 0.1 to 10 THz (1 THz = 1012 Hz), and a terahertz (THz) band radio using a very high carrier frequency of 100 GHz or more. can mean communication. THz waves are located between RF (Radio Frequency)/millimeter (mm) and infrared bands, and (i) transmit non-metal/non-polarizable materials better than visible light/infrared rays, and have a shorter wavelength than RF/millimeter waves and have high straightness. Beam focusing may be possible.

본 발명의 구체적인 실시 예Specific embodiments of the present invention

5G communication systems are beginning to utilize the mmWave band for higher data rates. mmWave communication can solve the bandwidth shortage issue. Also, mmWave communication can achieve a high data rate.

Massive multiple input multiple output (MIMO) technology is attracting attention to overcome the strong path loss of millimeter waves. For massive-MIMO, the transceiver can have a large antenna array. In order for a communication device using many antennas to perform digital beamforming, very large costs and power are incurred. In order to overcome this problem, a hybrid beamforming technique using a low-dimensional baseband beamformer and a high-dimensional analog beamformer together has been proposed.

Communication performance of a communication system using mmWave may vary greatly depending on changes in the surrounding environment. An intelligent reflecting surface (IRS) has recently been actively studied in academia and industry, and the IRS can reconstruct a communication environment in real time using only passive elements. The surface of the IRS consisting only of passive elements is inexpensive. IRS can be designed to be friendly to the communication environment. IRS can increase performance in mmWave communication systems. IRS is expected to play an important role in improving the coverage and spectral efficiency of millimeter wave communication systems along with massive MIMO and hybrid beamforming technologies. However, existing studies on intelligent reflective surfaces and hybrid beamformer design techniques for millimeter wave systems have been conducted to a very limited extent. Existing studies do not consider how mmWave channels are adjusted by the IRS pattern design. The present disclosure proposes an IRS design and hybrid beamforming technique in an OFDM MIMO communication system using millimeter wave. Accordingly, efficient beamforming can be performed.

The present disclosure can be applied to a single-user mmWave MIMO-OFDM system. The IRS reflection pattern design of this disclosure exploits the angular spasity of mmWave channels. The IRS reflection pattern design of the present disclosure can obtain a significant gain in spectral efficiency (SE). The hybrid beamformer design of the present disclosure may leverage a structure of adjusted channel matrices. In addition, the hybrid beamformer design of the present disclosure can achieve the performance of fully digital beamforming.

In this disclosure, vertical vectors and matrices may be indicated in boldface letters. The set of complex numbers can be denoted by C. C ^a×b represents a set of complex matrixes of size a×b. Transpose and Hermitian transpose can be written as (?)T and (?)H, respectively. [A](:,b) means the bth column of A. The element in the a-th row and b-th column of matrix A can be represented as [A](a,b). [A](:,1:b) is a matrix having the first b columns of A as column vectors. A matrix composed of the first a rows and b columns of matrix A can be denoted as [A](1:a,1:b). The Frobenius norm and determinant of A are respectively

and det(A). For a vector a, a diagonal matrix with elements on the diagonal can be denoted as diag(a). For some vector a, that

value is

can be denoted as The multivariate normal distribution with mean vector μ and covariance matrix Σ is

can be denoted as Ia denotes an identity matrix having a size of a×a. When a<b holds for any real numbers a and b, the values of the functions min(a,b) and max(a,b) are a and b, respectively. Abbreviations used in the present disclosure will be described below.

Table 2 below shows terms used in this disclosure. When the subscript includes UL, it corresponds to uplink, and when it includes DL, it corresponds to downlink.

The present disclosure proposes an IRS design and hybrid beamforming technique in an OFDM MIMO communication system using millimeter wave. The system assumes that a total of K subcarriers are used. The received signal on the kth subcarrier can be expressed as Equation 1 below.

[Equation 1]

A precoder used in each subcarrier satisfies the transmission power limitation condition. (

).The absolute values of the elements of analog precoder F _RF and combiner W _RF are respectively

is fixed with

A millimeter wave channel that undergoes frequency-selective fading can be expressed as in Equation 2a below.

[Equation 2a]

In Equation 2a, i represents the index of a channel.

represents the number of paths of H _i [k].

is the small-scale fading gain of the qth path of H _i [k], the receive array response vector, the transmit array response vector, the azimuth component of the angle of arrival, and the arrival It represents the elevation component of the angle, the radial component of the launch angle, and the elevation component of the launch angle.

An example of a millimeter wave channel that undergoes frequency-selective fading can be expressed as Equation 2b below.

[Equation 2b]

The frequency efficiency that can be achieved in the k-th subcarrier can be expressed as Equation 3a below.

[Equation 3a]

In Equation 3a, Rn[k] represents the covariance matrix of n[k] to which the combiner is applied. H _tot [k] represents all channels between the transmitter and the receiver in the kth subcarrier. This disclosure provides given channel information

Total frequency efficiency of OFDM system based on

IRS matrix Φ and hybrid beamformers that increase

Suggest a way to design

The maximiazation problem of frequency efficiency can be expressed as Equation 3b below.

[Equation 3b]

Specifically, the present disclosure proposes the following method to solve the above problems. First, the IRS matrix

designed to increase Second, W _RF and F _RF

designed to do Thirdly,

optimal considering

to design It is described in detail below.

Hereinafter, an IRS matrix design method will be described.

Receive array response matrix of millimeter wave channel H _i [k]

, small-scale fading matrix G _i [k] and transmit array response matrix

can be expressed as in Equation 4 below.

[Equation 4]

In Equation 4, i represents the index of a channel. Equation 4 does not lose its generality, and Equation 4 satisfies the assumption of Equation 5 below.

[Equation 5]

Based on the above-described Equation 4, the above-described Equation 2 can be expressed as the following Equation 6.

[Equation 6]

For any kth subcarrier, H _TI [k] and H _IR [k] can be considered. Among the small-scale fading paths of H _TI [k], α _{(TI, 0)} having the largest absolute value can be selected. And, the received array response vector corresponding to α _{(TI, 0)}

can be selected. Similarly, the transmit array response vector corresponding to α _IR,0 in the path of H _IR [k]

can be selected. The IRS matrix Φ can be expressed as in Equation 7 below.

[Equation 7a]

Based on Equation 7a, the following Equation 7b can be derived.

[Equation 7b]

In the proposed IRS reflection pattern, the IRS reflection matrix Φ is

is designed to increase

Is

increases with the eigenvalues of In addition, the following Equation 7c may be satisfied for each kth subcarrier.

[Equation 7c]

In addition, the proposed IRS reflection pattern may satisfy Equation 7d below.

[Equation 7d]

IRS typically deploys very many reflecting elements. That is, M is very large. therefore,

is large in the above system.

Analog beamforming has a transmission/reception system structure composed of one RF chain, a plurality of phase shifters, and signal attenuators. In full digital beamforming, an RF chain is connected to each individual antenna, and RF circuits such as a phase shifter and a signal attenuator are not used. Hybrid beamforming uses fewer RF chains than antennas. In addition, hybrid beamforming uses a digital beamformer in the baseband and an analog beamformer in the RF band. Hybrid beamforming can replace fully-digital baseband beamforming in massive MIMO systems. Referring to FIG. 12 , the hybrid beamformer includes baseband precoders 1202a and 1202b that are digital beamformers and

RF chains

1204a and 1204b that are analog beamformers.

A method for designing an analog beamformer will be described below.

The purpose is to design W _RF and F _RF as shown in Equation 8a below.

[Equation 8a]

Here, the channel matrices of all subcarriers

should consider

math formula

Assume that Φ is set as in Equation 7 above. In this case, the transmission array response matrix A _t at the transmitting end (TX) and the receiving array response matrix A _r at the receiving end (RX) may be defined as in Equation 8b below.

[Equation 8b]

For the k-th subcarrier, selecting a column vector from A _t can be expressed as Equation 9a below.

[Equation 9a]

At any kth subcarrier, H _tot [k] A _t is the largest of the column vectors

having

Vectors can be selected. A set of selected vectors can be expressed as (a) in Equation 9b. At this time,

Can be defined as (b) of Equation 9b.

[Equation 9b]

For the k-th subcarrier, selecting a column vector from _Ar can be expressed as Equation 10a below.

[Equation 10a]

Similarly,

is the largest of the column vectors in

having

Vectors of can be selected. The set of these selected vectors can be expressed as (a) of Equation 10b. At this time,

Can be defined as (b) of Equation 10b below.

[Equation 10b]

Based on the matrices defined in Equation 9, Equation 10a and Equation 10b described above

and

can be obtained. And, among the column vectors of A _t

most frequently appearing in the column of

Vectors can be selected. The selected vectors may be set to column vectors of the analog precoder F _RF . Similarly, among the column vectors of A _r

most frequently appearing in

Vectors can be selected. Also, the selected vectors may be set as column vectors of the analog combiner W _RF .

The following Equation 10c expresses the proposed analog beamformer design.

[Equation 10c]

Hereinafter, a baseband beamformer design will be described.

A problem related to the baseband beamformer can be expressed as Equation 11a below.

[Equation 11a]

Equation 11b shows that the problem of interest is reduced in relation to the baseband beamformer.

[Equation 11b]

Equation 11c represents an equation related to the optimal solution of the above problem.

[Equation 11c]

It is assumed that the IRS matrix Φ, the analog precoder F _RF and the analog combiner W _RF are designed by the methods described above in

Equations

1 and 2. The effective channel H _eff [k] in any k-th subcarrier can be expressed as in (a) of Equation 11d, and the singular value decomposition of the effective channel is (b) of Equation 11d can be expressed as

[Equation 11d]

Equation 11c does not lose its generality, and Equation 11c satisfies the assumption of Equation 12 below.

[Equation 12]

The baseband precoder F _BB [k] and the baseband combiner W _BB [k] may be expressed as in Equation 13 below, respectively.

[Equation 13]

In Equation 13,

is the power allocation matrix. Each power is given by Equation 14 (a), η [k] is selected to satisfy Equation 14 (b), and γ [k] is defined as Equation 14 (c) below. can

[Equation 14]

In addition, the proposed baseband beamformer can be expressed as Equation 15 below.

[Equation 15]

The performance of all-digital beamforming is achieved through the design of the baseband beamformer as described above.

In a time division duplexing (TDD) communication system, a transmitting end and a receiving end may each estimate a channel. The transmitting end and the receiving end may estimate a channel using an existing channel estimation method. Therefore, after estimating the channel, the receiving end may set the phase values of the IRS elements based on the above-described IRS design method. In addition, the transmitter may also set phase values of IRS elements based on the above-described IRS design method after estimating a channel. Then, the transmitter and the receiver may design a hybrid precoder and a combiner based on the analog beamformer design method and the baseband beamformer design method described above. Also, the transmitting end and the receiving end may communicate based on a hybrid precoder and combiner.

A frequency division duplexing (FDD) communication system does not have channel reciprocity. Therefore, only the receiving end estimates channel information. A receiving end may set phase values of IRS elements based on channel information. And, the receiving end may design a hybrid precoder and combiner based on the above-described analog beamformer design method and baseband beamformer design method. The receiving end may transmit information about the hybrid precoder or channel information to the transmitting end. Accordingly, the transmitting end and the receiving end may communicate using a precoder and a combiner, respectively.

13a and 13b show results according to an embodiment of the present disclosure. Here, it is assumed that the antenna of the transmitter, the antenna of the receiver, and the IRS elements are arranged in UPA structures of 8*8, 4*4, and 16*16, respectively. The number of transmission data streams and the number of RF chains are respectively

is set to The number of paths in H _i [k] is

Assume the power captured

Assume The sum of the transmit power limits of K subcarriers is

can be expressed as Each

It is assumed that the transmission power limit of the th subcarrier is P _TX [k] = P/K. 13(a) represents the frequency efficiency achieved by the above-described IRS matrix and hybrid beamformer design technique (proposed, hybrid) as a function of P in an OFDM system using K=16 subcarriers. 13(a) shows a result (proposed, fully-digital) when the IRS matrix design technique and digital beamforming are used together for comparison. In addition, FIG. 13(a) shows a case where the phase value of an IRS element is randomly set while digital beamforming is used (Random IRS, fully-digital) and a case where IRS does not exist (H _tot [k]=H _TR [k] ]). Referring to FIG. 13(a), the above-described IRS design technique greatly increases the frequency efficiency of an OFDM system. Also, FIG. 13(a) shows that the performance when the hybrid beamformer designed as described above is used is similar to the performance when digital beamforming is used. 13(b) shows the frequency efficiency achieved by the IRS matrix and hybrid beamformer according to the above-described technique in an OFDM system using K=64 subcarriers. 13(b) also shows that frequency efficiency is greatly improved in an OFDM system when the above-described technique is utilized.

In step S1401, the terminal may receive a reference signal from the base station through the IRS. For example, the terminal may receive at least one of a channel status information-reference signal (CSI-RS), a demodulation-reference signal (DM-RS), and a synchronization signal block (SSB) from the base station through the IRS. The terminal may transmit feedback on the received reference signal to the base station. For example, the terminal may transmit feedback on the received CSI-RS to the base station. As another example, the terminal may transmit feedback on the received DM-RS to the base station.

In step S1403, the terminal may set an IRS reflection matrix based on the received reference signal. For example, the UE may configure an IRS reflection matrix based on the received CSI-RS. As another example, the UE may configure an IRS reflection matrix based on the received SSB. For example, as described above with reference to FIGS. 11 to 13, the terminal may set an IRS reflection matrix.

In step S1405, the terminal may set a precoder and a combiner. For example, the terminal may set a precoder and a combiner based on the received reference signal. In addition, the terminal may set a precoder and a combiner based on the configured IRS reflection matrix. Also, the terminal may set the precoder and combiner as described above with reference to FIGS. 11 to 13 . For example, the precoder and combiner may each include an analog precoder and an analog combiner based on a reference signal received by the base station. Also, the precoder may include a baseband precoder based on a power allocation matrix. Also, the combiner may include a baseband combiner based on an effective channel of a subcarrier. Analog precoders and analog combiners can be based on matrix multiplication operations.

In step S1407, the terminal may receive a signal through the IRS based on the configured precoder and combiner. Specifically, the terminal may determine beamforming based on the set precoder and combiner. For example, beamforming may include reception beamforming for receiving a signal of a terminal and transmission beamforming for transmitting a signal of a terminal, and may not be limited to a specific form. That is, the terminal may receive a signal through the IRS based on the configured precoder and combiner, and through this, the terminal may determine beamforming to be used. After that, the terminal may receive a signal from the base station through the IRS based on the determined beamforming. The UE may estimate a channel based on TDD or FDD. In the case of TDD, the base station can also estimate the channel. For example, the base station may estimate a channel based on feedback information of the reference signal received from the terminal. The base station may estimate a channel based on channel reciprocity, and is not limited to the above-described embodiment. In the case of FDD, the terminal may transmit configuration information related to the precoder and the combiner to the base station. The base station may set a precoder and a combiner based on the received information.

In step S1501, the base station may transmit a reference signal to the terminal through the IRS. The base station may transmit at least one of a channel status information-reference signal (CSI-RS), a demodulation-reference signal (DM-RS), and a synchronization signal block (SSB) to the terminal through the IRS. The base station may receive feedback information of the reference signal from the terminal. In addition, the base station may receive a sounding reference signal (SRS) from the terminal.

In step S1503, the base station may receive configuration information related to the precoder and the combiner. Specifically, as described above with reference to FIGS. 11 to 13 , the precoder and combiner may be set, and setting information related to the precoder and combiner may be transmitted to the base station. In the case of FDD, the base station may configure the precoder and combiner based on configuration information related to the precoder and combiner received from the terminal. In the case of TDD, the base station may directly estimate a channel and set the precoder and combiner as described above with reference to FIGS. 11 to 13 .

In step S1503, the base station may transmit a signal to the terminal through the IRS based on the received configuration information. That is, in the case of FDD, the base station may determine beamforming based on the precoder and combiner setting related information received from the terminal. And, the base station may transmit a signal to the terminal through the IRS based on the determined beamforming.

It is obvious that examples of the proposed schemes described above may also be included as one of the implementation methods of the present disclosure, and thus may be regarded as a kind of proposed schemes. In addition, the above-described proposed schemes may be implemented independently, but may also be implemented in a combination (or merged) form of some proposed schemes. Information on whether the proposed methods are applied (or information on the rules of the proposed methods) may be defined so that the base station informs the terminal through a predefined signal (eg, a physical layer signal or a higher layer signal). .

The present disclosure may be embodied in other specific forms without departing from the technical ideas and essential characteristics described in the present disclosure. Accordingly, the above detailed description should not be construed as limiting in all respects and should be considered illustrative. The scope of the present disclosure should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent range of the present disclosure are included in the scope of the present disclosure. In addition, claims that do not have an explicit citation relationship in the claims may be combined to form an embodiment or may be included as new claims by amendment after filing.

Embodiments of the present disclosure may be applied to various wireless access systems. As an example of various wireless access systems, there is a 3rd Generation Partnership Project (3GPP) or 3GPP2 system.

Embodiments of the present disclosure may be applied not only to the various wireless access systems, but also to all technical fields to which the various wireless access systems are applied. Furthermore, the proposed method can be applied to mmWave and THz communication systems using ultra-high frequency bands.

Additionally, embodiments of the present disclosure may be applied to various applications such as free-running vehicles and drones.

Claims

In a method of operating a terminal in a wireless communication system,

Receiving, by the terminal, a channel status information-reference signal (CSI-RS) from a base station;

Transmitting feedback based on the received CSI-RS;

Setting an intelligent reflecting surface (IRS) reflection matrix based on the received CSI-RS, wherein the CSI-RS is transmitted through the IRS;

setting a precoder and a combiner based on the received CSI-RS;

determining beamforming based on the set precoder and combiner; and

Receiving a signal from the base station through the IRS based on the determined beamforming; method comprising.
According to claim 1,

The terminal is based on time division duplexing (TDD).
According to claim 1,

Transmitting configuration information related to the precoder and the combiner to the base station.
According to claim 3,

The terminal is based on frequency division duplexing (FDD).
According to claim 1,

The precoder includes an analog precoder based on the CSI-RS,

Wherein the combiner comprises an analog combiner based on the CSI-RS.
According to claim 5,

The precoder includes a baseband precoder based on a power allocation matrix;

Wherein the combiner comprises a baseband combiner based on an effective channel of a subcarrier.
According to claim 5,

Wherein the analog precoder and the analog combiner are based on matrix multiplication operations.
In a terminal in a wireless communication system,

transceiver; and

It includes a processor connected to the transceiver,

the processor,

Controls the transceiver to receive a channel status information-reference signal (CSI-RS) from a base station;

Controlling the transceiver to transmit feedback based on the received CSI-RS;

An intelligent reflecting surface (IRS) reflection matrix is set based on the received CSI-RS, and the CSI-RS is transmitted through the IRS,

Setting a precoder and a combiner based on the received CSI-RS;

Determining beamforming based on the set precoder and combiner;

Controlling the transceiver to receive a signal from the base station through the IRS based on the determined beamforming, the terminal.
According to claim 8,

The terminal is based on time division duplexing (TDD).
According to claim 8,

Transmitting configuration information related to the precoder and the combiner to the base station, the terminal.
According to claim 10,

The terminal is based on frequency division duplexing (FDD).
According to claim 8,

The precoder includes an analog precoder based on the CSI-RS,

The combiner includes an analog combiner based on the CSI-RS.
According to claim 12,

The precoder includes a baseband precoder based on a power allocation matrix;

The combiner includes a baseband combiner based on an effective channel of a subcarrier.
According to claim 12,

The analog precoder and the analog combiner are based on matrix multiplication operations.
In the communication device,

at least one processor;

at least one computer memory connected to the at least one processor and storing instructions directing operations as executed by the at least one processor;

The processor is the communication device,

Control to receive a channel status information-reference signal (CSI-RS) from the base station;

Control to transmit feedback based on the received CSI-RS;

Control to set an IRS reflection matrix based on the received CSI-RS, and the CSI-RS is transmitted through the IRS reflection matrix,

Control to set a precoder and a combiner based on the received CSI-RS;

Control to determine beamforming based on the set precoder and combiner,

Controlling to receive a signal from the base station through the IRS based on the determined beamforming, the communication device.
In a non-transitory computer-readable medium storing at least one instruction,

comprising the at least one instruction executable by a processor;

The at least one instruction is the computer readable medium,

Instructing to receive a channel status information-reference signal (CSI-RS) from the base station;

Instructing to transmit feedback based on the received CSI-RS;

Instructs to set an IRS reflection matrix based on the received CSI-RS, and the CSI-RS is transmitted through the IRS reflection matrix,

Instructing to set a precoder and a combiner based on the received CSI-RS;

Instructing to determine beamforming based on the set precoder and combiner;

A computer readable medium for instructing to receive a signal from the base station through the IRS based on the determined beamforming.
In the method of operating a base station in a wireless communication system,

Transmitting a channel status information-reference signal (CSI-RS) to the terminal;

Receiving setting information related to a precoder and a combiner from the terminal;

setting a precoder and a combiner based on the setting information;

determining transmission beamforming based on the set precoder and combiner; and

Transmitting a signal to the terminal through an intelligent reflecting surface (IRS) based on the determined transmission beamforming,

The configuration information is information on a precoder and a combiner configured by the terminal based on the CSI-RS, and the CSI-RS is transmitted through an IRS.
In a base station in a wireless communication system,

transceiver; and

It includes a processor connected to the transceiver,

the processor,

The transceiver controls to transmit a channel status information-reference signal (CSI-RS) to the terminal,

Controls the transceiver to receive setting information related to a precoder and a combiner from the terminal;

Setting a precoder and a combiner based on the setting information;

Determine transmit beamforming based on the set precoder and combiner;

Based on the determined transmission beamforming, control to transmit a signal to the terminal through an intelligent reflecting surface (IRS),

The configuration information is information on a precoder and a combiner configured by the terminal based on the CSI-RS, and the CSI-RS is transmitted through an IRS.