Rate-splitting method and apparatus for mitigating interference between neighboring cell and ris in multi-cell network environment

Abstract

A method according to an embodiment of the present specification comprises the steps of: transmitting information on resources related to CSI to terminals; receiving the CSI from each of the terminals; and transmitting a common message and private messages to the terminals on the basis of an MCS. The MCS is determined on the basis of i) a third SINR associated with the common message and ii) a fourth SINR associated with each of the private messages. On the basis of optimization for compensation of interference caused by a first cell, i) the third SINR and ii) the fourth SINR are determined.

Description

RATE-SPLITTING method and device for mitigating RIS interference between adjacent cells in a multi-cell network environment

[0001] The present invention relates to a rate-splitting method and apparatus for mitigating RIS interference with adjacent cells in a multi-cell network environment.

[0002] Mobile communication systems were developed to provide voice services while ensuring user mobility. However, mobile communication systems have expanded their scope to include data services as well as voice. Currently, due to the explosive increase in traffic leading to resource shortages and users demanding higher-speed services, more advanced mobile communication systems are required.

[0003] The requirements for next-generation mobile communication systems largely include the ability to accommodate explosive data traffic, a dramatic increase in transmission rates per user, a significantly increased number of connected devices, very low end-to-end latency, and high energy efficiency. To achieve this, various technologies are being researched, such as dual connectivity, massive multiple input multiple output (MMIMO), in-band full duplex, non-orthogonal multiple access (NOMA), super wideband support, and device networking.

[0004] Meanwhile, robustness, one of the characteristics of Rate-Splitting, is effective in managing mutual interference among multiple users. Each user can divide data transmission into multiple sub-bit rates, allowing for more flexible responses to changes in channel conditions, such as multipath fading. Therefore, RSMA utilizing Rate-Splitting is more robust against variability in channel conditions and can provide stable communication even in unstable environments. This characteristic can be a particularly effective solution for managing interference caused by intelligent reflectors, such as Reconfigurable Intelligence Surfaces (RIS). RIS is a technology that controls signal reflection to extend signal strength and coverage to the receiver.

[0005] However, RIS does not specifically process signals within a particular frequency band. That is, RIS does not reflect or scatter signals only within a specific frequency band, but can reflect signals across all frequency bands regardless of frequency (RIS no spectral selectivity). Due to this characteristic of RIS, unintended reflected signals may occur. These reflected signals can act as interference to other users (i.e., users who do not want the reflected signals from RIS).

[0006] As mentioned above, in order to operate an RIS, a method is required to effectively control and manage these unintended RIS reflection signals. To address the aforementioned problem caused by the RIS (RIS no spectral selectivity), research is being conducted in the direction of reducing interference between adjacent cells through RIS scheduling control and RIS beamforming control. However, in this case, the performance of adjacent cells using the RIS may be limited.

[0007] The purpose of this specification is to propose a method for managing interference between adjacent cells while maintaining the performance of adjacent cells (cells using RIS).

[0008] The technical problems to be solved in this specification are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this invention belongs from the description below.

[0009] A method according to one embodiment of the present specification includes the steps of transmitting information about resources related to Channel State Information (CSI) to terminals, receiving said CSI from each of said terminals, and transmitting a common message and private messages to said terminals based on a modulation and coding scheme (MCS).

[0010] The above resources are configured based on resource information of a first cell different from the serving cell of the terminals. The CSI includes i) a first Signal to Interference plus Noise Ratio (SINR) associated with the serving cell and ii) a second SINR associated with the serving cell and the first cell.

[0011] The above MCS is determined based on i) a third SINR associated with the above common message and ii) a fourth SINR associated with each of the above private messages.

[0012] Among the above terminals, the first terminals affected by interference by the first cell are determined based on the CSI.

[0013] Based on the optimization for compensating for the interference above, i) the third SINR and ii) the fourth SINR are determined.

[0014] The above common message and the above private message can be generated based on Rate Splitting Multiple Access (RSMA).

[0015] The first terminals may include a terminal among the terminals in which the second SINR is smaller than the first SINR.

[0016] The first cell mentioned above may be associated with a RIS (Reconfigurable intelligent surface).

[0017] Based on the above optimization related to the Weighted Maximum Mean Square Error (WMMSE), i) a first ratio related to the allocation of the common message to each of the first terminals, ii) a first precoding vector related to the common message, and iii) a second precoding vector related to the private message to each of the first terminals can be determined.

[0018] The above optimization can be performed such that a weighted sum based on i) the common message rate of each of the first terminals and ii) the private message rate of each of the first terminals is maximized.

[0019] The third SINR and the fourth SINR may be determined based on i) a ratio associated with the terminals and ii) a precoding vector associated with the terminals. The ratio associated with the terminals may include i) the first ratio and ii) a ratio associated with the allocation of the common message to each of the remaining terminals excluding the first terminals.

[0020] The precoding vector associated with the above terminals may include i) the first precoding vector, ii) the second precoding vector, and ii) a precoding vector associated with a private message for each of the remaining terminals.

[0021] A base station according to another embodiment of the present specification includes one or more transceivers, one or more processors for controlling the one or more transceivers, and one or more memories connected to the one or more processors for storing instructions.

[0022] The above instructions are characterized by causing the base station to perform all steps of any one of the above methods based on execution by the one or more processors.

[0023] An apparatus according to another embodiment of the present specification comprises one or more memories and one or more processors functionally connected to the one or more memories, wherein the one or more memories store instructions that cause the apparatus to perform all steps of any one of the methods based on execution by the one or more processors.

[0024] One or more non-transitory computer-readable media according to another embodiment of the present specification store instructions. The instructions, executable by one or more processors, are characterized by enabling a base station to perform all steps of any one of the methods.

[0025] A method according to another embodiment of the present specification includes the steps of receiving information about resources related to Channel State Information (CSI) from a base station, transmitting the CSI to the base station, and receiving a common message and a private message from the base station based on a modulation and coding scheme (MCS).

[0026] The above resources are set based on resource information of a serving cell and a first cell different from the serving cell. The CSI includes i) a first Signal to Interference plus Noise Ratio (SINR) associated with the serving cell and ii) a second SINR associated with the serving cell and the first cell.

[0027] The above MCS is determined based on i) a third SINR associated with the above common message and ii) a fourth SINR associated with each of the private messages.

[0028] Based on the optimization for compensating interference by the first cell, i) the third SINR and ii) the fourth SINR are determined.

[0029] A terminal according to another embodiment of the present specification includes one or more transceivers, one or more processors for controlling the one or more transceivers, and one or more memories connected to the one or more processors for storing instructions.

[0030] The above instructions are characterized by enabling the terminal to perform all steps of the method based on execution by the one or more processors.

[0031] According to the embodiments of the present specification, the effect of interference caused by an adjacent cell (e.g., a cell using RIS) can be minimized without limiting the performance of the adjacent cell.

[0032] The effects obtainable in this specification are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below.

[0033] FIG. 1 is a drawing illustrating an example of a communication system applicable to the present specification.

[0034] FIG. 2 is a drawing illustrating an example of a wireless device that can be applied to the present specification.

[0035] FIG. 3 is a diagram illustrating a method for processing a transmission signal applicable to the present specification.

[0036] FIG. 4 is a drawing illustrating another example of a wireless device to which the present specification applies.

[0037] FIG. 5 is a drawing illustrating an example of a portable device to which the present specification applies.

[0038] FIG. 6 is a diagram illustrating physical channels applicable to the present specification and a signal transmission method using them.

[0039] Figure 7 is a figure showing an example of a communication structure that can be provided in a 6G system.

[0040] Figure 8 is a diagram illustrating interference caused by the RIS of an adjacent cell.

[0041] Figure 9 is a diagram illustrating interference caused by an unintended RIS reflected beam.

[0042] Figure 10 illustrates a communication environment in an RSMA system.

[0043] Figure 11 illustrates the baseband transceiver structure in an RSMA system.

[0044] Figure 12 illustrates a conventional wireless environment.

[0045] Figure 13 illustrates an intelligent wireless environment.

[0046] Figure 14 illustrates a communication theory model for a conventional wireless environment.

[0047] Figure 15 illustrates a communication theory model for an intelligent wireless environment.

[0048] Figure 16 illustrates a wireless communication environment in which interference occurs between adjacent cells.

[0049] Figure 17 illustrates a procedure for estimating interference terminals in a multi-cell environment.

[0050] FIG. 18 illustrates resource allocation for distinguishing interfering terminals.

[0051] Figure 19 illustrates a problem-solving procedure based on an objective function.

[0052] FIG. 20 illustrates a wireless communication environment that performs cooperative communication.

[0053] Figure 21 illustrates an interference measurement procedure for RIS-based cooperative communication.

[0054] Figure 22 is a diagram illustrating the reduction of interference caused by an interference terminal.

[0055] FIG. 23 is a flowchart illustrating a method according to one embodiment of the present specification.

[0056] FIG. 24 is a flowchart illustrating a method according to another embodiment of the present specification.

[0057] The following embodiments are combinations of the components and features of this 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 not combined with other components or features. Additionally, some components and / or features may be combined to constitute the embodiments of this specification. The order of operations described in the embodiments of this specification may be changed. Some components or features of any embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment.

[0058] In the description of the drawings, procedures or steps that could obscure the gist of the specification have not been described, nor have procedures or steps that are understandable to those skilled in the art been described.

[0059] Throughout the specification, when a part is described as "comprising" or "including" a component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, terms such as "...part," "...unit," and "module" as used in the specification refer to a unit that performs at least one function or operation, and this may be implemented in hardware, software, or a combination of hardware and software. Additionally, "one (a or an)," "one," "the," and similar related terms may be used in the context describing this specification (particularly in the context of the following claims) to include both singular and plural forms, unless otherwise indicated in this specification or clearly contradicted by the context.

[0060] 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 refers to a terminal node of a network that communicates directly with a mobile station. Specific operations described herein as being performed by a base station may, in some cases, be performed by an upper node of the base station.

[0061] That is, in a network consisting of multiple 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, 'base station' may be replaced by terms such as fixed station, Node B, eNB (eNode B), gNB (gNode B), ng-eNB, advanced base station (ABS), or access point.

[0062] Additionally, in the embodiments of this 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).

[0063] Furthermore, the transmitting end refers to a fixed and / or mobile node that provides data or voice services, and the receiving end refers to a fixed and / or mobile node that receives data or voice services. Therefore, in the case of the uplink, a mobile station can be the transmitting end and a base station can be the receiving end. Similarly, in the case of the downlink, a mobile station can be the receiving end and a base station can be the transmitting end.

[0064] The embodiments of this specification may be supported by standard documents disclosed in at least one of the wireless access systems, such as IEEE 802.xx systems, 3GPP (3rd Generation Partnership Project) systems, 3GPP LTE (Long Term Evolution) systems, 3GPP 5G (5th generation) NR (New Radio) systems and 3GPP2 systems, and in particular, the embodiments of this specification may be supported by the documents 3GPP TS (technical specification) 38.211, 3GPP TS 38.212, 3GPP TS 38.213, 3GPP TS 38.321 and 3GPP TS 38.331.

[0065] In addition, the embodiments of this specification may be applied to other wireless access systems and are not limited to the systems described above. For example, they may be applicable to systems applied after the 3GPP 5G NR system and are not limited to specific systems.

[0066] That is, obvious steps or parts not described in the embodiments of this specification may be described by referring to the aforementioned documents. Additionally, all terms disclosed in this specification may be explained by the aforementioned standard documents.

[0067] Hereinafter, preferred embodiments according to the present specification will be described in detail with reference to the accompanying drawings. The detailed description disclosed below, together with the accompanying drawings, is intended to describe exemplary embodiments of the present specification and is not intended to represent the only embodiment in which the technical configuration of the present specification can be implemented.

[0068] Additionally, specific terms used in the embodiments of this specification are provided to aid in understanding this specification, and the use of such specific terms may be modified in other forms without departing from the technical spirit of this specification.

[0069] 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).

[0070] For the sake of clarity in the following description, the explanation is based on 3GPP communication systems (e.g., LTE, NR, etc.), but the technical concept of the present invention is not limited thereto. LTE may refer to technology from 3GPP TS 36.xxx Release 8 onwards. Specifically, LTE technology from 3GPP TS 36.xxx Release 10 onwards is referred to as LTE-A, and LTE technology from 3GPP TS 36.xxx Release 13 onwards may be referred to as LTE-A pro. 3GPP NR may refer to technology from TS 38.xxx Release 15 onwards. 3GPP 6G may refer to technology from TS Release 17 and / or Release 18 onwards. "xxx" indicates a standard document detail number. LTE / NR / 6G may be collectively referred to as 3GPP systems.

[0071] Regarding the background technology, terms, abbreviations, etc. used in this specification, reference may be made to matters described in standard documents published prior to the present invention. For example, reference may be made to standard documents 36.xxx and 38.xxx.

[0072] Communication systems applicable to the present specification

[0073] Although not limited thereto, the various descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this specification may be applied to various fields requiring wireless communication / connection (e.g., 5G) between devices.

[0074] Examples are provided in more detail below with reference to the drawings. In the following drawings and descriptions, the same reference numerals may represent the same or corresponding hardware blocks, software blocks, or function blocks unless otherwise described.

[0075] FIG. 1 is a drawing illustrating an example of a communication system to which the present specification applies. Referring to FIG. 1, the communication system (100) to which the present specification applies includes a wireless device, a base station, and a network. Here, a wireless device refers to a device that performs communication using wireless access technology (e.g., 5G NR, LTE) and may be referred to as a communication / wireless / 5G device. Although not limited thereto, a 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, a vehicle may include a vehicle equipped with wireless communication capabilities, an autonomous vehicle, a vehicle capable of performing inter-vehicle communication, etc. Here, the vehicle (100b-1, 100b-2) may include an unmanned aerial vehicle (UAV) (e.g., a drone). The XR device (100c) includes an augmented reality (AR) / virtual reality (VR) / mixed reality (MR) device 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 device (100d) may include a smartphone, a smart pad, a wearable device (e.g., a smartwatch, smart glasses), a computer (e.g., a laptop, etc.). The home appliance (100e) may include a TV, a refrigerator, a washing machine, etc. The IoT device (100f) may include a sensor, a smart meter, 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 for other wireless devices.

[0076] Wireless devices (100a to 100f) can be connected to a network (130) through a base station (120). AI technology may be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (100g) through the network (130). The network (130) can be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network. The wireless devices (100a to 100f) may communicate with each other through the base station (120) / network (130), but they may 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). Also, IoT devices (100f) (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0077] Wireless communication / connection (150a, 150b, 150c) can be established between wireless devices (100a~100f) / base station (120) and between base station (120) / base station (120). Here, 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 wireless communication / connection (150a, 150b, 150c), wireless devices and base stations / wireless devices, and base stations and base stations can transmit / receive wireless signals to / from each other. For example, wireless communication / connection (150a, 150b, 150c) can transmit / receive signals through various physical channels. To this end, based on the various proposals of this specification, at least some of the following may be performed: a process for setting various configuration information for transmitting / receiving wireless signals, a process for various signal processing (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), a resource allocation process, etc.

[0078] Communication systems applicable to the present specification

[0079] FIG. 2 is a drawing illustrating an example of a wireless device that can be applied to the present specification.

[0080] 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)} may correspond to {the wireless device (100x), the base station (120)} and / or {the wireless device (100x), the wireless device (100x)} of FIG. 1.

[0081] The 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 transceivers (206a) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or sequences of operation disclosed herein. For example, the processor (202a) may process information within the memory (204a) to generate a first information / signal and then transmit a wireless signal containing the first information / signal through the transceiver (206a). Additionally, the processor (202a) may receive a wireless signal containing a second information / signal through the transceiver (206a) and then store information obtained from the signal processing of the second information / signal in the memory (204a). 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 store software code including instructions for performing some or all of the processes controlled by the processor (202a) or for performing the descriptions, functions, procedures, proposals, methods, and / or sequences of operation disclosed in this specification. Here, the processor (202a) and memory (204a) may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). A transceiver (206a) may be connected 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 receiver. The transceiver (206a) may be combined with an RF (radio frequency) unit. In this specification, a wireless device may refer to a communication modem / circuit / chip.

[0082] The second wireless device (200b) includes one or more processors (202b) and one or more memories (204b), and may additionally include one or more transceivers (206b) and / or one or more antennas (208b). The processor (202b) controls the memory (204b) and / or transceivers (206b) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or sequences of operation disclosed herein. For example, the processor (202b) may process information within the memory (204b) to generate a third information / signal and then transmit a wireless signal containing the third information / signal through the transceiver (206b). Additionally, the processor (202b) may receive a wireless signal containing a fourth information / signal through the transceiver (206b) and then store information obtained from the 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 store software code including instructions for performing some or all of the processes controlled by the processor (202b) or for performing the descriptions, functions, procedures, proposals, methods, and / or sequence diagrams of operation disclosed in this specification. 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 through one or more antennas (208b). The transceiver (206b) may include a transmitter and / or receiver. The transceiver (206b) may be used in combination with an RF unit. In this specification, a wireless device may refer to a communication modem / circuit / chip.

[0083] 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 PHY (physical), MAC (media access control), RLC (radio link control), PDCP (packet data convergence protocol), RRC (radio resource control), and SDAP (service data adaptation protocol). One or more processors (202a, 202b) may generate one or more PDUs (Protocol Data Units) and / or one or more SDUs (service data units) according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation 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 flowcharts of operation disclosed in this specification. One or more processors (202a, 202b) may generate a signal (e.g., baseband signal) including a PDU, SDU, message, control information, data, or information according to the functions, procedures, proposals, and / or methods disclosed in this specification and provide it to one or more transceivers (206a, 206b). One or more processors (202a, 202b) may receive a signal (e.g., baseband signal) from one or more transceivers (206a, 206b) and may obtain a PDU, SDU, message, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this specification.

[0084] 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, 202b). Descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed herein may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. Firmware or software configured to perform the descriptions, functions, procedures, proposals, methods, and / or operation sequences disclosed in this specification may be included in one or more processors (202a, 202b) or stored in one or more memories (204a, 204b) and driven by one or more processors (202a, 202b). The descriptions, functions, procedures, proposals, methods, and / or operation sequences disclosed in this specification may be implemented using firmware or software in the form of code, instructions, and / or sets of instructions.

[0085] One or more memories (204a, 204b) may be connected to one or more processors (202a, 202b) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. One or more memories (204a, 204b) may be composed of ROM (read-only memory), RAM (random access memory), EPROM (erasable programmable read-only memory), flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. One or more memories (204a, 204b) may be located inside and / or outside of one or more processors (202a, 202b). Additionally, 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.

[0086] One or more transceivers (206a, 206b) may transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or operation flowcharts, etc., of this specification to one or more other devices. One or more transceivers (206a, 206b) may receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or operation flowcharts, etc., disclosed in this specification from one or more other devices. For example, one or more transceivers (206a, 206b) may be connected to one or more processors (202a, 202b) and may transmit and receive wireless signals. For example, one or more processors (202a, 202b) may 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 connected 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, etc., as described in the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed herein through one or more antennas (208a, 208b). In this specification, one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports). One or more transceivers (206a, 206b) can convert the received wireless signal / channel, etc. from an RF band signal to a baseband signal in order to process the received user data, control information, wireless signal / channel, etc. using one or more processors (202a, 202b).One or more transceivers (206a, 206b) can convert user data, control information, wireless signals / channels, etc. processed using one or more processors (202a, 202b) from baseband signals to RF band signals. To this end, one or more transceivers (206a, 206b) may include (analog) oscillators and / or filters.

[0087] FIG. 3 is a diagram illustrating a method for processing a transmission signal applicable to the present specification. For example, the transmission signal may be processed by a signal processing circuit. In this case, 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). In this case, for example, the operation / function of FIG. 3 may be performed in the processor (202a, 202b) and / or transceiver (206a, 206b) of FIG. 2. Also, for example, the hardware element of FIG. 3 may be implemented in the processor (202a, 202b) and / or 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, but are not limited to the above-described embodiment.

[0088] A 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 may include a transmission block (e.g., UL-SCH transmission block, DL-SCH transmission block). The wireless signal may be transmitted through various physical channels (e.g., PUSCH, PDSCH) of FIG. 6. Specifically, the codeword can be converted into a scrambled bit sequence by a scrambler (310). The scrambled sequence used for scrambling is generated based on an initialization value, which may include ID information of a wireless device, etc. The scrambled bit sequence may be modulated into a modulation symbol sequence by a modulator (320). The modulation method may include pi / 2-BPSK (pi / 2-binary phase shift keying), m-PSK (m-phase shift keying), m-QAM (m-quadrature amplitude modulation), etc.

[0089] A complex modulation symbol sequence can be mapped to one or more transmission layers by a layer mapper (330). The modulation symbols of each transmission layer can be mapped to the corresponding antenna port(s) by a precoder (340) (precoding). The output z of the precoder (340) can be obtained by multiplying the output y of the layer mapper (330) by an N*M precoding matrix W, where 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., a discrete Fourier transform (DFT)) on the complex modulation symbols. Alternatively, the precoder (340) can perform precoding without performing transform precoding.

[0090] A resource mapper (350) can map the modulation symbols of each antenna port to a time-frequency resource. The time-frequency resource may include multiple symbols (e.g., CP-OFDMA symbols, DFT-s-OFDMA symbols) in the time domain and multiple subcarriers in the frequency domain. A signal generator (360) generates a radio signal from the mapped modulation symbols, and the generated radio signal can be transmitted to another device through each antenna. To this end, the signal generator (360) may include an inverse fast Fourier transform (IFFT) module, a cyclic prefix (CP) inserter, a digital-to-analog converter (DAC), a frequency uplink converter, etc.

[0091] The signal processing process for a received signal in a wireless device can be configured as the inverse of the signal processing process (310–360) of FIG. 3. For example, a wireless device (e.g., 200a, 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 may include a frequency downlink converter, an analog-to-digital converter (ADC), a CP remover, and a fast Fourier transform (FFT) module. Subsequently, the baseband signal can be restored into a codeword through a resource de-mapper process, a postcoding process, a demodulation process, and a de-scrambling process. The codeword can be restored into the 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.

[0092] Wireless device structure applicable to the present specification

[0093] FIG. 4 is a drawing illustrating another example of a wireless device to which the present specification applies.

[0094] 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 / parts, 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 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 additional elements (440) and controls the general operation of the wireless device. For example, the control unit (420) may control the electrical / mechanical operation of the wireless device based on a program / code / command / information stored in the memory unit (430). Additionally, the control unit (420) may transmit information stored in the memory unit (430) to an external (e.g., another communication device) via a wireless / wired interface through the communication unit (410), or store information received from an external (e.g., another communication device) via a wireless / wired interface through the communication unit (410) in the memory unit (430).

[0095] The additional element (440) can be configured in various ways depending on the type of 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 financial device), a security device, a climate / environment device, an AI server / device (Fig. 1, 140), a base station (Fig. 1, 120), a network node, etc. Wireless devices can be used in a movable or fixed location depending on the use—e.g., service.

[0096] 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 partially connected via a communication unit (410). For example, within the wireless device (400), the control unit (420) and the communication unit (410) may be connected via a wire, and the control unit (420) and the first unit (e.g., 430, 440) may be connected wirelessly via the communication unit (410). Additionally, each element, component, unit / part, and / or module within the wireless device (400) may include one or more additional elements. For example, the control unit (420) may be composed of one or more sets of processors. 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.

[0097] Mobile devices to which this specification applies

[0098] FIG. 5 is a drawing illustrating an example of a portable device to which the present specification applies.

[0099] FIG. 5 illustrates a portable device to which the present specification applies. The portable device may include a smartphone, a smartpad, a wearable device (e.g., a smart watch, smart glasses), a portable computer (e.g., a laptop, etc.). The portable device may be referred to as an MS (mobile station), UT (user terminal), MSS (mobile subscriber station), SS (subscriber station), AMS (advanced mobile station), or WT (wireless terminal).

[0100] 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 part of the communication unit (510). Blocks 510 to 530 / 540a to 540c correspond to blocks 410 to 430 / 440 of FIG. 4, respectively.

[0101] 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 the components of the portable device (500) to perform various operations. The control unit (520) may include an application processor (AP). The memory unit (530) can store data / parameters / programs / code / commands required for the operation of the portable device (500). Additionally, the memory unit (530) can store input / output data / information, etc. The power supply unit (540a) supplies power to the portable device (500) and may include wired / wireless charging circuits, batteries, etc. The interface unit (540b) can support the connection between the portable device (500) and other external devices. The interface unit (540b) may include various ports (e.g., audio input / output ports, video input / output ports) for connection with external devices. The input / output unit (540c) can receive or output video information / signals, audio information / signals, data, and / or information input from a user. The input / output unit (540c) may include a camera, a microphone, a user input unit, a display unit (540d), a speaker and / or a haptic module, etc.

[0102] For example, in the case of data communication, the input / output unit (540c) acquires information / signals (e.g., touch, text, voice, image, video) input by the user, and the acquired 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 another wireless device or to a base station. Additionally, the communication unit (510) can receive wireless signals from another wireless device or base station and then restore the received wireless signals to their original information / signals. The restored information / signals are stored in the memory unit (530) and then can be output in various forms (e.g., text, voice, image, video, haptic) through the input / output unit (540c).

[0103] Physical channels and general signal transmission

[0104] In a wireless access system, a terminal can receive information from a base station via a downlink (DL) and transmit information to a base station via an 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 and purpose of the information they transmit and receive.

[0105] FIG. 6 is a diagram illustrating physical channels applicable to the present specification and a signal transmission method using them.

[0106] When a terminal is turned on again after being turned off, or when it newly enters a cell, it performs initial cell search operations, such as synchronizing with the base station, in step S611. To do this, the terminal receives the primary synchronization channel (P-SCH) and secondary synchronization channel (S-SCH) from the base station to synchronize with the base station and obtain information such as the cell ID.

[0107] Subsequently, the terminal can obtain in-cell broadcast information by receiving a physical broadcast channel (PBCH) signal from the base station. Meanwhile, during the initial cell search phase, the terminal can check the downlink channel status by receiving a Downlink Reference Signal (DL RS). After completing the initial cell search, the terminal can obtain more specific system information by receiving the physical downlink control channel (PDCCH) and the physical downlink shared channel (PDSCH) based on the physical downlink control channel information in step S612.

[0108] Subsequently, the terminal may perform a random access procedure, such as steps S613 through S616, to complete the connection to the base station. To this end, the terminal transmits a preamble through a physical random access channel (PRACH) (S613) and receives a random access response (RAR) for the preamble through a physical downlink control channel and a corresponding physical downlink shared channel (S614). The terminal transmits a physical uplink shared channel (PUSCH) using scheduling information within the RAR (S615) and performs a contention resolution procedure, such as receiving a physical downlink control channel signal and a corresponding physical downlink shared channel signal (S616).

[0109] A terminal that has performed the procedure described above may subsequently perform the reception of a physical downlink control channel signal and / or a physical downlink shared channel signal (S617) and the 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.

[0110] Control information transmitted by a terminal to a base station is collectively referred to as uplink control information (UCI). UCI includes HARQ-ACK / NACK (hybrid automatic repeat and request acknowledgment / negative-ACK), SR (scheduling request), CQI (channel quality indication), PMI (precoding matrix indication), RI (rank indication), BI (beam indication) information, etc. In this case, UCI is generally transmitted periodically via PUCCH, but depending on the embodiment (e.g., when control information and traffic data need to be transmitted simultaneously), it may be transmitted via PUSCH. Additionally, the terminal may transmit UCI non-periodically via PUSCH in response to a request or instruction from the network.

[0111] Figure 7 is a figure showing an example of a communication structure that can be provided in a 6G system.

[0112] 6G systems are expected to have 50 times higher simultaneous wireless connectivity than 5G wireless communication systems. URLLC, a key feature of 5G, will become an even more dominant technology in 6G communication by providing end-to-end latency of less than 1ms. Unlike the frequently used area spectrum efficiency, 6G systems will exhibit significantly superior volume spectrum efficiency. 6G systems can provide very long battery life and advanced battery technologies for energy harvesting, meaning mobile devices in 6G systems will not require separate charging. New network characteristics in 6G may include the following.

[0113] - Satellite Integrated Network: 6G is expected to be integrated with satellites to provide a global mobile population. Integrating terrestrial, satellite, and airborne networks into a single wireless communication system is crucial for 6G.

[0114] - Connected Intelligence: Unlike previous generations of wireless communication systems, 6G is innovative and will update wireless evolution from "connected things" to "connected intelligence." AI can be applied at each stage of the communication process (or at each step of the signal processing described below).

[0115] - 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.

[0116] - Ubiquitous Super 3D Connectivity: Connectivity to the network and core network functions of drones and very low Earth orbit satellites will create Super 3D connectivity in 6G ubiquitous.

[0117] Some general requirements regarding the new network characteristics of 6G mentioned above may be as follows.

[0118] - Small cell networks: The idea of ​​small cell networks was introduced to improve the quality of received signals in cellular systems as a result of increased throughput, energy efficiency, and spectrum efficiency. Consequently, small cell networks are an essential feature of communication systems for 5G and beyond 5G (5GB). Therefore, 6G communication systems also adopt the characteristics of small cell networks.

[0119] - Ultra-dense heterogeneous network: Ultra-dense heterogeneous networks will be another important characteristic of 6G communication systems. Multi-tier networks composed of heterogeneous networks improve overall QoS and reduce costs.

[0120] - High-capacity backhaul: Backhaul connections are characterized as high-capacity backhaul networks to support high-volume traffic. High-speed fiber optics and free-space optics (FSO) systems can be possible solutions to this problem.

[0121] - 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.

[0122] - Softwarization and virtualization: Softwarization and virtualization are two important features that form the basis of the design process in 5GB networks to ensure flexibility, reconfigurability, and programmability. Additionally, billions of devices can be shared across a shared physical infrastructure.

[0123] < Reconfigurable intelligent surface (RIS) >

[0124] RIS is a plate-shaped device made of electromagnetic (EM) material. Because RIS can be controlled electronically, it is expected to have high utility in the field of wireless communication. Generally, wireless communication environments are difficult to control artificially, but RIS opens up the possibility of controlling wireless environments. Through the utilization of RIS, it may ultimately become possible to control wireless communication environments.

[0125] The biggest advantage of RIS is that it can change the radio environment as desired to improve the quality of the received signal.

[0126] The main characteristics of RIS are as follows.

[0127] Since RIS is a passive element, it does not require an energy source such as a power supply.

[0128] RIS is a continuous plate-shaped element that can shape all waveforms entering the RIS into a desired form and reflect them.

[0129] Since RIS does not require an ADC (Analog to Digital Converter) or DAC (Analog to Digital Converter), it is not affected by receiver noise.

[0130] Since RIS does not have a specific operating frequency, it can be used across the entire available band.

[0131] RIS can be easily deployed. For example, RIS can be simply attached to the exterior walls of a building, the ceiling of an interior, the walls or ceiling of a factory, human clothing, etc., and operated.

[0132] Rate-splitting is an advanced strategy used in multiple access communication systems that enables efficient data transmission when multiple users simultaneously share a single frequency band. The basic idea is to maximize transmission efficiency by dividing the entire data bit into multiple parts and allocating each part to different users for transmission. This splitting is performed by considering various channel conditions or requirements among the diverse users, and the divided data is transmitted simultaneously. Each user receives the data part allocated to them, restores it, and reconstructs the original data. Currently, the rate-splitting technique is being researched as RSMA (Rate-Splitting Multiple Access), a type of multiple access method, and is being proposed as a technology focused on the efficient utilization of frequency resources.

[0133] Methods utilizing the characteristics of Rate-Splitting technology are currently being continuously researched. Robustness, one of these characteristics, is effective in managing mutual interference among multiple users. Each user can divide data transmission into multiple sub-bit rates, allowing for a more flexible response to changes in channel conditions, such as multipath fading. Therefore, RSMA utilizing Rate-Splitting is more robust against channel condition variability and can provide stable communication even in unstable environments. Furthermore, this characteristic can be an effective solution for managing interference caused by intelligent reflectors, such as Reconfigurable Intelligence Surfaces (RIS). RIS is a technology that controls signal reflection to extend signal strength and coverage to the receiver. However, RIS does not specifically process signals within a particular frequency band. In other words, RIS does not reflect or scatter signals only within a specific frequency band; instead, it can reflect signals across all frequency bands regardless of frequency. This can generate unintended reflected signals through the RIS, which can ultimately result in interference for users who do not want these reflected signals. In order to actually operate an RIS, a method is needed to effectively control and manage these unintended RIS reflection signals.

[0134] The descriptions of terms and abbreviations used in this specification are as follows.

[0135] - RSMA (Rate Splitting Multiple Access): Rate Division Multiple Access

[0136] - OMA (Orthogonal Multiple Access): Orthogonal Multiple Access

[0137] - SC (Superposition Coding): Nested coding

[0138] - SIC (Successive Interference Cancellation): Sequential interference cancellation

[0139] - RIS (Reconfigurable Intelligent Surface): Intelligent reflector

[0140] - SRE (Smart Radio Environment): Intelligent wireless environment

[0141] In this specification, User may be interpreted / replaced with Terminal (UE).

[0142] This specification proposes a method to guarantee communication performance by utilizing the ability to manage interference in the Downlink RSMA technique in a multi-cell network environment. In particular, in interoperability technologies for multi-cell network environments such as CoMP (Coordinated Multiple-Point), multiple base stations cooperate to provide services to users; however, multipath interference and other factors occur during this process, resulting in performance degradation due to interference. The proposed technique describes a method for measuring interference between multi-cell networks and compensating for the resulting performance degradation through the robustness of RSMA. Furthermore, the proposed technique also proposes a method to compensate for performance degradation caused by interference in the RIS.

[0143] In current wireless communication environments, research aimed at reducing or overcoming interference utilizes methods such as Beamforming, MIMO, Small Cell, and Dynamic Spectrum Access to manage interference. Research on these methods has primarily focused on reducing the signals causing interference to minimize interference affecting surrounding users. Similarly, in multi-cell network environments, interference effects between neighboring cells are reduced by regulating the signals of the interfering cell or through frequency scheduling. Cross-Link Interference (CLI), proposed by 3GPP, is also a technique for managing inter-cell interference. Like the previously described methods, CLI assumes mutual synchronization between cells and allocates resources to minimize interference by combining signals between base stations.

[0144] Furthermore, we propose a method to manage and mitigate situations where performance degradation occurs due to unintended reflected signals from adjacent cells caused by an RIS when signal reinforcement and coverage expansion are achieved through the RIS in a multi-cell network environment. Since adjacent cells utilize different frequencies, interference between cells can be ignored. However, when an RIS is installed in a specific cell, unintended signals may be generated from adjacent cells using different frequencies, potentially leading to performance degradation. This is because the RIS does not reflect signals targeting only a specific frequency band. This characteristic of the RIS—no spectral selectivity—can create difficulties in actual installation. To prevent performance degradation caused by unintended signals generated by the RIS, methods have been proposed to manage and mitigate interference caused by the RIS in a multi-cell network environment.

[0145] Current research on interference management in RIS focuses on methods to mitigate interference from existing cells using RIS, as well as cases where unintended interference occurs due to RIS. To mitigate interference from existing cells using RIS, methods to control interference through RIS phase shifting are being considered. Research is directed toward maximizing SINR by considering the interference of the relevant cells through the RIS. Another approach to mitigating interference from existing cells using RIS is to effectively control interference generated by the RIS. Due to the nature of RIS, radio waves cannot be reflected only at specific frequencies, which can generate unintended reflected beams and cause interference. Research is currently underway on interference cancellation methods optimized to account for this phenomenon.

[0146] Research on controlling interference using RIS proceeds in a direction that maximizes throughput by minimizing the impact of interference in the interference channel. In other words, according to the aforementioned research, phase shift optimization for the RIS is performed for the purpose of interference nulling. More specifically, a two-stage optimization technique is used to achieve the maximum sum-rate. First, based on the solution that minimizes interference, an alternating projection algorithm is executed to obtain the maximum sum-rate through Riemannian Conjugate Gradient (RCG) optimization. Since the problem of satisfying minimum interference and maximum sum-rate is a non-convex problem, it must be solved based on an alternating optimization algorithm. In a channel with multiple users, the transmitter The channel between and RIS Defined as, and RIS and receiver The liver channel It is defined as. The reflection coefficient of the RIS is Defined as, and the phase shift of the i-th element of RIS (phase shift of i-th element) is Defines as. Each transmitter transmission symbol If you say that, the receiver The signal received via RIS It is equal to the following mathematical formula 1.

[0147]

[0148] Therefore, the achievable rate of receiver k can be defined as shown in Equation 2 below.

[0149]

[0150] Here, is the transmit power level transmitted to receiver k. Here, the condition for interference nulling is as follows.

[0151]

[0152]

[0153] is a condition that the intended signal must be greater than 0, and ... is a condition corresponding to unintended interference. In this case, the achievable rate is given by the following mathematical equation 3.

[0154]

[0155] RIS is used as a solution to find the achievable rate of minimum interference under the above conditions and to derive the maximum sum-rate that satisfies this condition.

[0156] Throughput has been improved using RIS, but research is also being conducted on the resulting interference. For example, interference may occur in a scenario such as that shown in Fig. 8.

[0157] Figure 8 is a diagram illustrating interference caused by the RIS of an adjacent cell.

[0158] Specifically, Figure 8 illustrates Terminal 2 (User 2) being affected by interference caused by the RIS of an adjacent cell (BS1). This scenario involves communication degradation occurring due to radio waves reflected through the RIS from cells using the same frequency band. This problem can only be resolved if the User affected by the interference recognizes the issue and reports it to their serving cell. Specifically, as shown in the example in Figure 8, when interference occurs from BS1 to User 2 in BS2, a device is required to measure the interference and notify BS1. Current research attempts to solve this problem by assuming that each cell (BS1 and BS2) is connected to each other via Xn / X2. BS1 can transmit information regarding RIS scheduling to BS2 to inform User 2 when it is affected by the RIS. Based on this information, BS2 transmits a Measurement Report setting to User 2 that allows it to measure RIS interference, and User 2 measures the interference according to the RIS scheduling and reports it to BS2. When BS2 transmits information reported by User2 to BS1, BS1 performs RIS scheduling based on that information to reduce the effects of interference. This method solves the problem by adjusting RIS scheduling between cells affected by RIS that use the same frequency band.

[0159] For example, interference may occur in a scenario such as that shown in Fig. 9. Fig. 9 is a diagram illustrating interference caused by an unintended RIS reflected beam.

[0160] Generally, cell planning is performed to ensure that adjacent cells use different frequency bands. Nevertheless, if the RIS location is susceptible to influence from adjacent cells, a situation like the one shown in Fig. 9 may occur. Although BS2 performs RIS phase optimization to increase User2's throughput by using the RIS to overcome obstacles, a situation arises where radio waves from the adjacent cell BS1 affect User1_1 through interference via the RIS. In this case, BS1 must inform BS2 that its cell users are being affected by interference from the RIS and perform RIS optimization while also considering the interference impact on BS1's cell users. To achieve this, an optimization problem must be defined that considers both BS1 and BS2. First, the user reception signal of BS2, which directly controls the RIS, is given by Equation 4 below.

[0161]

[0162] Here, BS1, RIS, and the link are It is defined as, and the links between RISs in BS2 are It is defined as. The transmitted signal vector is It is defined as, corresponds to noise. The reflection coefficient matrix in RIS is a diagonal matrix It is expressed as In this case, each component is a passive component.

[0163] In the problematic scenario, the signal reflected through the RIS applies equally across all frequency ranges. Therefore, the User received signal of BS1 affected by interference is given by Equation 5 below.

[0164]

[0165] As shown in the scenario illustrated in Figure 9 above, users belonging to BS1 can also be affected by RIS. Additionally, BS1 is an RIS channel Without considering only direct channels Transmit beamforming vector considering only Because it is configured in such a way, it can manifest as serious interference for users in BS1. Accordingly, an RIS design method was studied to achieve an appropriate balance by considering all users in each cell (BS1, BS2). First, the reflection channel of BS2 using the RIS can be represented as shown in Equation 6 below.

[0166]

[0167] Here, the gain of all reflection channels for BS2 users is expressed as Equation 7 below.

[0168]

[0169] Likewise, if we express the channel gain for BS1 users It can be expressed as follows. Here, if the channel gain for BS1 is considered as interference, the following mathematical equation 8 is given.

[0170]

[0171] Therefore, the gain relationship between BS1 and BS2 is The problem can be solved by finding an appropriate RIS beamforming that can maximize it.

[0172] Currently, research on eliminating or reducing interference using RIS, or on eliminating interference caused by RIS, is being conducted in a manner similar to the aforementioned examples, where the throughput of the cell using RIS is sacrificed to some extent to compensate for the performance degradation of the interfering cell. However, dividing resources through scheduling or optimizing RIS beamforming vectors to appropriately reduce interference from adjacent cells assumes that the maximum performance of the cell actually using RIS cannot be extracted. This creates a situation where the RIS, intended to enhance the communication performance of user terminals, is intentionally used at a reduced performance due to unintended interference from adjacent cells. Research is required to manage interference caused by RIS as much as possible while guaranteeing communication performance through RIS.

[0173] <RSMA(Rate Splitting Multiple Access)>

[0174] RSMA technology is a multiple access technique in wireless communication systems that provides a method for efficiently managing interference and resources among multiple users. Its key feature is the division of messages into common messages and private messages. Furthermore, since common messages can be eliminated through sequential interference cancellation techniques, interference caused by common messages can be removed when decoding private messages. In other words, when decoding private messages, only interference from other users' private messages exists. This means that the rate at which interference signals can be decoded can be controlled.

[0175] RSMA technology is still in the research stage where standards have not yet been established, and therefore there are no precise guidelines on how to use frequency and time resources. However, research exists that proceeds in the same direction as the frequency usage methods used in NOMA (Non-orthogonal Multiple Access) technology. That is, all users share frequency and time resources. This will be explained below with reference to Figures 10 and 11.

[0176] FIG. 10 illustrates a communication environment in an RSMA system. Specifically, FIG. 10 illustrates k terminals using an RSMA-based communication environment.

[0177] Figure 11 illustrates the baseband transceiver structure in an RSMA system.

[0178] Specifically, FIG. 11 shows the structure of a 1-layer RS ​​(Rate Split) transmitter and receiver for k terminals. Depending on the antenna structure of the transmitter and receiver class The number of can change.

[0179] The transmitter on the left is a baseband structure for transmitting messages to k terminals. The 1-layer RS ​​structure combines the common message of all terminals into one and transmits the remaining private messages to each terminal. The message from each terminal is Represented as, and shared message by Message Splitter private message It is divided into. Each user's shared messages are combined by the Common Message Combiner. It forms, and individual messages are separated, enter an encoder, and are encoded. It forms. Subsequently, precoding is performed by the precoder, and transmission occurs after RF processing. Therefore, at the transmitter, k+1 messages are transmitted as signals. It forms, and here It depends on the transmitting and receiving antennas. Transmitted signal It is equal to the following mathematical formula 9.

[0180]

[0181] The signal received by the k-th terminal It is equal to mathematical formula 10 below.

[0182]

[0183] is the channel for terminal k, and is a precoding matrix, and is Gaussian Channel Noise.

[0184] The transmission rates of each user's shared messages and private messages are given by the following mathematical formulas 11 and 12.

[0185]

[0186]

[0187] In addition, for all terminals to decrypt the shared message, they must satisfy the conditions according to Equation 13 below.

[0188]

[0189] Referring to FIG. 11, in the receiver of terminal k When receiving, first share the message Decodes it. And the original message Decrypted shared message Remove using the Sequential Interference Cancellation (SIC) technique, and decode the remaining private messages. Decoded shared message private message Each is combined through Combine to form the message of terminal k.

[0190] A wireless environment and an intelligent wireless environment will be described below with reference to FIGS. 12 and 13.

[0191] Smart Radio Environment

[0192] According to current wireless technology, H, the channel in the wireless environment, is defined as naturally fixed and uncontrollable random. Therefore, an optimal transmission and reception method adapted to that channel is sought.

[0193] FIG. 12 illustrates a conventional wireless environment. Specifically, FIG. 12 illustrates a conventional wireless communication technology that adapts to a wireless environment. According to conventional wireless communication technology, the transceiver is controlled to optimize communication. Conventional wireless technology optimizes by recognizing and compensating for the current channel, but limitations arise in poor NLOS environments, such as dead zones.

[0194]

[0195] According to Shannon's capacity limit, no matter how much the transmitted signal P is precoded and processed, the channel If the size is small, it is impossible to increase channel capacity. Therefore, intelligent wireless environment technology has emerged that uses a configurable intelligent surface (RIS) to use the wireless channel environment as a factor to control the transceiver.

[0196] Figure 13 illustrates an intelligent wireless environment.

[0197] Specifically, FIG. 13 illustrates an intelligent wireless environment technology (SRE) called Wireless 2.0. According to the intelligent wireless environment technology, the channel H of the wireless environment is considered a controllable factor, and Joint Optimization is performed by adding the environment (channel) H to End-Points Optimization.

[0198] A theoretical communication model for a wireless environment will be explained below with reference to FIGS. 14 and FIGS. 15.

[0199] Figure 14 illustrates a communication theory model for a conventional wireless environment. Figure 15 illustrates a communication theory model for an intelligent wireless environment. Referring to Figures 14 and 15, the current wireless communication environment is denoted as P1, and the intelligent wireless environment is denoted as P2. P1 and P2 represent the probability of receiving a signal y when a signal x is sent, respectively.

[0200] Referring to Fig. 14, in the current wireless environment, P1 is fixed, and the receiver (Decoder) measures the transmitted signal and sends feedback to the transmitter. Based on the feedback, the transmitter controls the transceiver to adapt to the communication environment. As a specific example, the receiver (e.g., terminal) measures the Channel Quality Indicator (CQI) for the transmitted signal and feeds it back to the transmitter (e.g., base station). Based on this, the transmitter adjusts the MCS and informs the receiver.

[0201] Referring to Fig. 15, in an intelligent wireless environment, wireless environment P2 is recognized and the wireless environment can be changed through RIS control. At the same time, feedback is received from the receiver, and the transceiver can also be optimized.

[0202] Below, the structure and operating principle for the embodiments of the present specification will be examined in detail with reference to FIGS. 16 to 22.

[0203] First, we examine the scenario environment configuration related to the embodiments of this specification.

[0204] The structure and method proposed in this specification assume a situation in which interference occurs between neighboring cells in a mobile communication environment where k terminals exist based on a Downlink RSMA system. Generally, the probability of interference occurring between adjacent cells is low, but when performing cooperative communication such as CoMP, operations to match the frequency bands of the terminals occur, and this can lead to interference. In particular, when the Serving cell and the Coordinated cell use the same frequency, such as in techniques that use the same frequency band (Coordinated Beamforming, Joint Transmission, Dynamic Point Selection), the impact of such interference is bound to increase when terminals at the edge of the cell perform cooperative communication.

[0205] According to the embodiments of this specification, interference between cooperative communication cells is compensated using a rate-splitting technique. This operation is performed by engaging with the cells affected by the interference, rather than engaging with the cells causing the interference. This is intended to ensure maximum communication performance between neighboring cells or during cooperative communication. To this end, each cell (base station) must measure the channel and interference through Channel State Information (CSI) by sharing resources where interference may occur in advance.

[0206] FIG. 16 illustrates a wireless communication environment in which interference occurs between adjacent cells. Specifically, FIG. 16 shows a wireless communication environment in which interference occurs when adjacent cells use the same frequency. is a channel from the serving cell, and is a channel from an interfering cell. It can provide higher quality services to the terminal (User), but it can act as interference to the interference terminal (Interference User). Here, the interference terminal (Interference User) refers to a terminal that receives interference from the interfering cell.

[0207] An interfering cell uses the same frequency as a serving cell for a specific period, and during this time, interference occurs to other terminals of the serving cell. To verify interference to the terminals, it is necessary to separately measure the channel state when the interfering cell operates at the same frequency as the serving cell. Furthermore, based on these measurement results, a rate-splitting technique must be applied to compensate for performance degradation caused by interference in the serving cell. This will be explained in detail below with reference to Figures 17 and 18.

[0208] FIG. 17 illustrates a procedure for estimating interference terminals in a multi-cell environment. Specifically, FIG. 17 illustrates a procedure for sharing resource information to measure interference between adjacent cells.

[0209] In S1710, the Serving cell requests resource information from the Interfering cell.

[0210] In S1720, the interfering cell shares resource information with the serving cell.

[0211] In S1730, the serving cell allocates CSI-related resources to terminals (e.g., terminal 1 to terminal k) based on resource information from the interfering cell. The CSI-related resources may include CSI-IM resources and / or CSI-RS resources.

[0212] In S1740, the serving cell and the interfering cell perform communication at the same frequency. For example, the serving cell and the interfering cell transmit a reference signal to terminals based on the same frequency. The reference signal may be transmitted based on resources associated with the CSI.

[0213] In S1750, the terminals compute channel state information based on measurements of the reference signal. The terminals report the channel state information to the serving cell.

[0214] In S1760, the serving cell (base station) estimates the interference user(s) of the interfering cell.

[0215] In S1770, the serving cell (base station) performs rate-splitting optimization for the interference user(s).

[0216] In S1780, the serving cell (base station) communicates with terminals based on rate-splitting optimization.

[0217] FIG. 18 illustrates resource allocation for distinguishing interfering terminals.

[0218] Specifically, FIG. 18 illustrates resource allocation for distinguishing and measuring interfering terminals. Resource information may or may not be shared in advance according to the CoMP technique. The procedure assumes that resource information is shared for channel measurement. Based on the shared resource information, terminals of the Serving cell measure the channel by distinguishing between cases where they communicate only through the Serving cell and cases where they perform cooperative communication through the Interfering cell. When terminals report channel measurement results (i.e., CSI) including communication with the Interfering cell, the Serving cell can estimate the interfering terminals receiving interference from the Interfering cell based on this. The Serving cell performs and applies rate-splitting-based optimization to compensate for the degraded channel condition for the interfering terminals.

[0219] Rate-Splitting Technique for Interference Mitigation in Multi-Cell Network Environments

[0220] The Rate-Splitting technique according to the embodiments of this specification is a technique that maximizes interference protection by performing Rate-Splitting-based optimization on the resources of a Serving cell when interference is received from an adjacent Neighbor cell in a Downlink RSMA environment. This technique compensates for interference by adjusting the resources of the Serving cell receiving interference through the Rate-Splitting technique, rather than controlling or managing the Neighbor cell that is the cause of the interference. This method prioritizes ensuring the signal performance of the intended user by the Neighbor cell and resolves the resulting side effects of interference from other users within the Serving cell.

[0221] Based on resource information from the Interfering cell (Neighbor cell), terminals of the Serving cell perform channel measurements, including when the Interfering cell operates at the same frequency. Through Channel State Information (CSI) reports, the Serving cell can estimate the terminals whose channel state deteriorates due to interference when the Interfering cell is operating. This set of terminals is denoted as K. The K terminals are in a state where SINR degradation has occurred due to interference from the adjacent cell, and such interference occurs whenever the adjacent cell performs cooperative communication.

[0222] Equation 15 below represents the SINR associated with the common message of terminal k, and Equation 16 represents the SINR associated with the private message of terminal k.

[0223]

[0224]

[0225] Measured SINR ( , If the Modulation and Coding Scheme (MCS) is applied as is based on the above, interfering terminals affected by interference from the interfering cell experience communication performance degradation. Optimization is performed to compensate for this. Specifically, rate-splitting optimization aimed at compensating for interference from the interfering cell is performed on the interfering terminals. Additionally, the existing communication performance must be guaranteed for normal terminals in the Serving cell that are not affected by interference. A set of terminals K degraded by interference is determined, and a set of interfering terminals U satisfying the conditions of Equation 17 below is determined, and optimization is performed on the corresponding set U. The rates for each terminal k with respect to the SINR of the channel measurement results are given by Equations 18 and 19 below.

[0226]

[0227] is the Serving cell SINR for terminal k, and is the interfering cell SINR for terminal k. is the common message rate for terminal k, and is the private message rate for terminal k. is the threshold rate for terminal k.

[0228]

[0229]

[0230] The conditions of the aforementioned mathematical formula 17 will be explained in detail below.

[0231] When the terminals of the serving cell report channel measurement results including the interfering cell, the serving cell begins estimating the set of interfering terminals U for the SINR based on this. SINR when only the serving cell is operating SINR when the interfering cell operates together Satisfying this small condition, the rate of Common / Private messages( , If ) is greater than the rate of terminal k that must be guaranteed at a minimum, terminal k is included in the set of interfering terminals U. is the minimum message threshold rate that must be guaranteed, and each terminal k( It is determined that there is enough resource margin to perform optimization because the rate of ) must be greater than at least the guaranteed value to decode the message.

[0232] After configuring the interference terminal set U, rate-splitting optimization is performed on it. is a precoding vector for user data streams belonging to the interference terminal set U. is an element corresponding to Common message rate allocation We achieve the maximum sum rate through the optimization of and c. To this end, we establish an objective function and solve the problem using mathematical methods. It is a non-convex problem. To solve the optimization problem, techniques such as Random Precoding, Weighted Matched Beamforming, Singular Vector Decomposition, and Weighted Maximum Mean Square Error (WMMSE) may be utilized. According to the embodiments of this specification, interference compensation is performed through the WMMSE technique to optimize the degradation of transmission and reception performance caused by interference. The optimization function below is Weight Determine the Precoder and Common message rate that can achieve the maximum Sum-rate (WSR) for each Weight by setting it.

[0233] In the objective function below, several constraints (conditions (1) to (4) below) must be guaranteed. First, a rate at which all users can decode common messages must be guaranteed. RSMA is fundamentally a method in which all users decode common messages, then remove interference through SIC, and finally decode their own messages among the remaining private messages. Therefore, the ability to decode common messages must be a prerequisite; if this is not met, users cannot receive messages normally. Specifically, the following conditions (1) to (4) must be guaranteed.

[0234] Condition (1): Since the Common message includes all terminals K, including the interfering terminal set U, the Common message rate of each user must be greater than the Common message rate allocation of all terminals.

[0235] Condition (2): Precoding vector to perform optimization The maximum power allocated to the interference terminal set U It must be within the boundary.

[0236] Condition (3): The sum of the Common / Private message rates must be greater than the QoS requirement of each terminal.

[0237] Condition (4): Common message rate to perform mitigation for interference It must be greater than or equal to 0.

[0238] The mathematical formula 20 below represents the objective function and conditions (1) to (4) described above.

[0239]

[0240] Here, represents the sum of the common message rate allocation C for each terminal, and represents the total transmit power. Specifically, tr() is a trace operation, and is a matrix It represents the sum of the diagonal elements. And, am. is a precoding matrix as a composite precoder matrix and diagonal power allocation It consists of. is the QoS threshold common rate allocation vector.

[0241] As a result, the Common message ratio of terminals corresponding to the interference terminal set U is If we include the resources of the remaining terminals of the existing Serving cell, the common message ratio for K terminals is It is defined as. The precoder of each data stream is optimized for the set of interfering terminals U after It is calculated as, and the precoder of the data stream for K terminals, including the remaining terminals of the Serving cell, is It can be defined as. Fig. 19 shows the procedure for solving the problem when conditions for solving the proposed problem are applied.

[0242] Figure 19 illustrates a problem-solving procedure based on an objective function.

[0243] In S1910, the above-described conditions are applied to the objective function for approximation of the objective function using the Sample Averate Approximation technique. At this time, the following (19A) are assumed.

[0244] Interference terminal set U

[0245] U's maximum power

[0246] U's threshold rate

[0247] Convergence threshold for optimization

[0248] t=0

[0249] Composite precoding matrix and Common message allocation rate Based on (Weighted Sum Rate)(19B) is calculated.

[0250] In S1920, Weight for optimizing interference based on conditions is calculated. Specifically, through the WMMSE technique is calculated.

[0251] In S1930, calculated According to and is calculated. Specifically, through the Alternation Optimization technique and is calculated.

[0252] In S1940, and The difference between ( ) is the convergence threshold for optimization If it is greater than or equal to, t is increased and then the operation is performed starting from S1920. convergence threshold for optimization Optimization is complete when it is smaller. At this time, the parameters that satisfy the optimization condition silver It can be displayed as.

[0253] Through the method described above, terminals included in the interference terminal set U acquire a Common / Private message ratio to compensate for interference situations, and interference is mitigated due to the SIC operation of the Common message upon message reception. To mitigate interference, the Common message ratio increases within the constraint boundary. Therefore, the newly defined SINR is achieved through Rate-Splitting optimization. , By newly applying the MCS corresponding to each stream based on this, it becomes possible to receive throughput that can compensate for interference. is the common message It is a SINR with applied, This corresponds to the SINR of private messages with common messages removed through SIC.

[0254]

[0255]

[0256] Rate-Splitting Technique for RIS Interference Mitigation in Multi-Cell Network Environments

[0257] Figure 20 illustrates a wireless communication environment performing cooperative communication. Specifically, Figure 20 depicts a situation where interference between adjacent cells occurs due to the RIS in a mobile communication environment where K terminals based on a Downlink RSMA system exist. Below, we introduce a technique that maximizes the mitigation of RIS interference by performing rate-splitting-based optimization on the resources of a no-RIS cell. A cell using RIS is referred to as an RIS cell, and an adjacent cell not using RIS is referred to as a no-RIS cell. The reflection coefficient matrix, which is the phase of the RIS, for improving communication performance between the RIS cell and the RIS cell user in the RIS cell It is expressed as follows. The RIS cell user k can receive a signal according to the following mathematical formula 23.

[0258]

[0259] The RIS cell user of the RIS cell receives the signal RIS optimization is performed for the optimization of. At this time, the received signal of the Interference user of the no RIS cell is influenced by the adjacent RIS cell and takes the form of Equation 24 below.

[0260]

[0261] is the Interference user's direct channel, and is a channel reflected through the RIS.

[0262] Here, the signal corresponding to interference It is assumed to be an unintended signal because it was designed for the RIS cell user present in the RIS cell. That is, the SINR of the Interference user k. When expressed as in Equations 25 and 26, the component of no RIS cell user is It must correspond to the channel component of the RIS This is added and is effectively expressed as shown in Equations 27 and 28 below. RIS channel component When expressed as the RIS reflection coefficient matrix It can be expressed as.

[0263] Equations 25 and 26 relate to the scenario without RIS, and Equations 27 and 28 relate to the scenario with RIS.

[0264]

[0265]

[0266]

[0267]

[0268] Unintended interference signal here Since the channel components through the RIS are designed for the RIS cell user present in the RIS cell, they are left untouched to guarantee the performance of the cell, and interfering channels are minimized and direct channel Resources must be distributed to maximize [the value]. According to the embodiments of this specification, a method is proposed to improve SINR by reducing unintended signal interference caused by RIS through resource optimization of no RIS cells using the RSMA Rate-Splitting technique. Additionally, similar to the previous scenario, the aim is to improve the receiver's throughput through an MCS with SINR compensation applied.

[0269] Figure 21 illustrates an interference measurement procedure for RIS-based cooperative communication.

[0270] In S2110, the RIS cell performs RIS channel optimization.

[0271] In S2120, the RIS cell shares resource information with no RIS cell.

[0272] In S2130, the no RIS cell allocates CSI-related resources to terminals (No RIS cell users) based on the resource information of the RIS cell. The CSI-related resources may include CSI-IM resources and / or CSI-RS resources.

[0273] In S2140, the RIS cell and no RIS cell perform communication at the same frequency. For example, the RIS cell and no RIS cell transmit a reference signal to terminals based on the same frequency. The reference signal may be transmitted based on resources associated with the CSI.

[0274] In S2150, the terminals compute channel state information based on measurements of the reference signal. The terminals report the channel state information to the serving cell.

[0275] In S2160, no RIS cell (base station) estimates the interference user(s) of the RIS cell.

[0276] In S2170, no RIS cell (base station) performs rate-splitting optimization for interference user(s).

[0277] In S2180, no RIS cell (base station) communicates with terminals based on rate-splitting optimization.

[0278] When the RIS cell performs optimization on the RIS phase reflection coefficient matrix φ, it shares the information regarding this with adjacent cells (no RIS cells). If the RIS is used during a specific resource period, the RIS cell transmits information about that resource to the no RIS cells. If the RIS is used regardless of the resource, the RIS cell transmits information indicating whether the RIS is active or de-active to the no RIS cells. Channel measurements are performed to measure the impact on No RIS cell users after the RIS operation is applied, and an interference terminal set U is formed through the channel state information report regarding this. The conditions for determining the interference terminal set U are given by the following Equation 29.

[0279]

[0280] is the no RIS cell SINR for terminal k, and is the RIS cell SINR for terminal k. is the common message rate for terminal k, and is the private message rate for terminal k. is the threshold rate for terminal k.

[0281] When terminals of the No RIS cell report channel measurement results including the RIS cell, the No RIS cell begins to estimate the interference terminal set U for the SINR based on this. The SINR of the No RIS cell SINR when the RIS of the RIS cell is activated Satisfying this small condition, the rate of Common / Private messages of terminal k( , If ) is greater than the minimum guaranteed rate, terminal k is included in the interference terminal set U. is the minimum message threshold rate that must be guaranteed, and each terminal k( It is determined that there is enough resource margin to perform optimization because the rate of ) must be greater than at least the guaranteed value to decode the message.

[0282] The optimization objective function for compensating for RIS interference caused by adjacent cells (RIS cells) for the interfering terminal set U is the same as in the previous scenario (Rate-Splitting technique for interference mitigation in a multi-cell network environment). Based on the same constraints, the Common message ratio for the interfering terminal set U , precoding vector of each data stream This can be obtained as a result, and this is a newly defined SINR , Based on (Equations 30 and 31 below), a new MCS corresponding to each stream is applied.

[0283]

[0284]

[0285] According to the present embodiment, interference compensation SINR calculated through the Rate-Splitting technique of RSMA in a situation where RIS interference occurs , This is estimated. If an MCS based on the estimated SINR is applied, the reception throughput can be improved. This embodiment proposes a method to compensate for user interference in cells receiving interference (serving cell, no RIS cell, etc.) without affecting the performance of the cell causing the interference (interfering cell, RIS cell) at all. Interference reduction will be explained below with reference to FIG. 22.

[0286] Figure 22 is a diagram illustrating the reduction of interference caused by an interference terminal.

[0287] Referring to FIG. 22, interference corresponds to the portion of power based on a received message excluding power based on a common message and a private message (user k). Interference is reduced through interference optimization based on the embodiments described above. For example, the effect of interference reduction can be obtained by adjusting the ratio of the common message.

[0288] The effects derived from the embodiments described above will be explained in detail below.

[0289] According to an embodiment of the present specification, a method for compensating for interference caused by adjacent cells in a multi-cell network environment is enhanced by utilizing the Rate-Splitting technology of RSMA. If information regarding the resources causing interference from the neighboring cell causing the interference is known, the serving cell can distinguish the users of the interference originating from the neighboring cell, and thereby apply interference compensation technology only to specific users. Within the serving cell, resource constraints that do not affect other users (( ), ( ), ( To compensate for interference within )), optimization of Common and Private messages (see Fig. 19) is performed, and users receiving interference from neighboring cells can expect an improvement in SINR through the receiver's SIC function from the optimized Common message. Therefore, the optimized SINR estimated value ( , Applying ) to the MCS look-up table makes it possible to compensate for performance degradation caused by interference from adjacent cells.

[0290] In terms of implementation, the operations of the base station / terminal according to the embodiments described above can be processed by the device of FIGS. 1 to 5 described above (e.g., the processor (202a, 202b) of FIG. 2).

[0291] In addition, the operations of the base station / terminal according to the above-described embodiment may be stored in memory (e.g., 204a, 204b of FIG. 2) in the form of instructions / programs (e.g., instructions, executable code) for driving at least one processor (e.g., processor (202a, 202b) of FIG. 2).

[0292] The embodiments described above will be explained in detail below with reference to FIGS. 23 and FIGS. 24 in terms of the operation of base stations and terminals. The methods described below are distinguished only for convenience of explanation, and it is understood that a part of one method may be substituted with a part of another method or combined with one another and applied.

[0293] FIG. 23 is a flowchart illustrating a method according to one embodiment of the present specification.

[0294] Referring to FIG. 23, a method according to one embodiment of the present specification includes the step of transmitting information about resources related to CSI (S2310), the step of receiving CSI (S2320), and the step of transmitting common message and private message (S2330).

[0295] In S2310, the base station transmits information regarding resources related to Channel State Information (CSI) to the terminals. The resources are configured based on the resource information of the serving cell of the terminals and a first cell different from it.

[0296] For example, the first cell may be an interfering cell (see FIG. 16, FIG. 17) or an RIS cell (see FIG. 20, FIG. 21). The serving cell may be a cell that does not use RIS (e.g., no RIS cell) (see FIG. 20). For example, the first cell may be associated with a RIS (Reconfigurable intelligent surface).

[0297] In S2320, the base station receives the CSI from each of the terminals. The CSI includes i) a first Signal to Interference plus Noise Ratio (SINR) associated with the serving cell and ii) a second SINR associated with the serving cell and the first cell.

[0298] In S2330, the base station transmits common messages and private messages to the terminals based on a modulation and coding scheme (MCS).

[0299] For example, the common message and the private message may be generated based on Rate Splitting Multiple Access (RSMA).

[0300] According to one embodiment, the MCS may be determined based on i) a third SINR associated with the common message and ii) a fourth SINR associated with each of the private messages. The third SINR and the fourth SINR may be determined based on at least one of the embodiments described above. They will be explained in detail below.

[0301] Specifically, among the terminals, first terminals affected by interference from the first cell can be determined based on the CSI. The first terminals may be terminals belonging to the aforementioned set of interference terminals U. Based on the optimization for compensation of the interference, i) the third SINR and ii) the fourth SINR can be determined.

[0302] The first terminals may include a terminal among the terminals in which the second SINR is smaller than the first SINR. For example, the second SINR is of Equation 17. Based on, and the first SINR is of Equation 17 It can be based on. For example, the above second SINR is of Equation 29 Based on, and the first SINR is of Equation 29 It can be based on.

[0303] According to one embodiment, based on the optimization related to the Weighted Maximum Mean Square Error (WMMSE), i) a first ratio related to the allocation of the common message to each of the first terminals, ii) a first precoding vector related to the common message, and iii) a second precoding vector related to the private message to each of the first terminals may be determined.

[0304] For example, the above-mentioned first ratio is as described above It can be based on. For example, the first precoding vector described above is Based on It may mean, and the above second precoding vector is at It can mean the remaining precoding vectors excluding .

[0305] The above optimization is i) the common message rate of each of the first terminals (e.g., ) and ii) the private message rate of each of the first terminals (e.g., It can be performed to maximize the weighted sum based on ). For example, the optimization can be performed based on Equation 20.

[0306] The above third SINR and the above fourth SINR may be determined based on i) a ratio associated with the terminals and ii) a precoding vector associated with the terminals. For example, the ratio is as described above. It may mean... For example, the above-mentioned precoding vector is the aforementioned It can mean.

[0307] The ratios related to the above terminals may include i) the first ratio and ii) the ratios related to the allocation of the common message to each of the remaining terminals excluding the first terminals.

[0308] The precoding vector associated with the above terminals may include i) the first precoding vector, ii) the second precoding vector, and ii) a precoding vector associated with a private message for each of the remaining terminals.

[0309] For example, the third SINR may be based on Equation 21 or Equation 30. For example, the fourth SINR may be based on Equation 22 or Equation 31.

[0310] Operations based on S2310 to S2330 described above can be implemented by the device of FIG. 2. For example, a base station (200a or 200b) can control one or more transceivers (206a or 206b) and / or one or more memories (204a or 204b) to perform operations based on S2410 to S2430.

[0311] The embodiments described above will be explained in detail below with reference to FIG. 24 regarding the operation of the terminal. The methods described below are distinguished only for the convenience of explanation, and it is obvious that a part of one method may be substituted with a part of another method or combined with one another and applied.

[0312] FIG. 24 is a flowchart illustrating a method according to another embodiment of the present specification.

[0313] Referring to FIG. 24, a method according to another embodiment of the present specification includes the step of receiving information about resources related to CSI (S2410), the step of transmitting CSI (S2420), and the step of receiving common message and private message (S2430).

[0314] In S2410, the terminal transmits information regarding resources related to Channel State Information (CSI) from the base station. These resources are configured based on resource information of the serving cell and a first cell other than the first cell.

[0315] In S2420, the terminal transmits the CSI to the base station. The CSI includes i) a first Signal to Interference plus Noise Ratio (SINR) associated with the serving cell and ii) a second SINR associated with the serving cell and the first cell.

[0316] In S2430, the terminal receives a common message and a private message from the base station based on a modulation and coding scheme (MCS).

[0317] The above MCS may be determined based on i) a third SINR associated with the above common message and ii) a fourth SINR associated with each of the private messages.

[0318] Based on the optimization for compensating for interference by the first cell, i) the third SINR and ii) the fourth SINR can be determined.

[0319] Operations based on S2410 to S2430 correspond to operations based on S2310 to S2330 described in FIG. 23. Considering the above correspondence, redundant descriptions are omitted. That is, a specific description of a terminal operation can be replaced with the description / execution of FIG. 23 corresponding to the operation.

[0320] Operations based on S2410 to S2430 described above can be implemented by the device of FIG. 2. For example, a terminal (200a or 200b) can control one or more transceivers (206a or 206b) and / or one or more memories (204a or 204b) to perform operations based on S2310 to S2330.

[0321] Here, the wireless communication technology implemented in the wireless devices (200a, 200b) of this specification may include LTE, NR, and 6G, as well as Narrowband Internet of Things for low-power communication. For example, NB-IoT technology may be an example of LPWAN (Low Power Wide Area Network) technology and may be implemented according to standards such as LTE Cat NB1 and / or LTE Cat NB2, but is not limited to the names mentioned above. Additionally, or generally, the wireless communication technology implemented in the wireless devices (200a, 200b) of this specification may perform communication based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and may be referred to by various names such as eMTC (enhanced Machine Type Communication). For example, LTE-M technology may be implemented in 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 names mentioned above. Additionally or generally, wireless communication technology implemented in the wireless devices (200a, 200b) of this specification may include at least one of ZigBee, Bluetooth, and Low Power Wide Area Network (LPWAN) for low-power communication, and is not limited to the names mentioned above. As an example, ZigBee technology can create personal area networks (PANs) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and may be referred to by various names.

[0322] The embodiments described above are combinations of the components and features of this specification in a specific form. Each component or feature should be considered optional unless otherwise explicitly stated. Each component or feature may be implemented in a form not combined with other components or features. Additionally, it is possible to construct embodiments of this specification by combining some components and / or features. The order of operations described in the embodiments of this 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 embodiments may be constructed by combining claims that do not have an explicit citation relationship in the claims, or that they may be included as new claims through amendments made after filing.

[0323] Embodiments according to the present specification may be implemented by various means, e.g., hardware, firmware, software, or a combination thereof. In the case of implementation by hardware, 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, etc.

[0324] 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 memory and executed by a processor. The memory may be located inside or outside the processor and may exchange data with the processor by various known means.

[0325] It is obvious to those skilled in the art that this specification may be embodied in other specific forms without departing from the essential features of this specification. Accordingly, the detailed description set forth above should not be interpreted restrictively in all respects but should be considered illustrative. The scope of this specification shall be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of this specification are included within the scope of this specification.

Claims

1. Regarding the method, A step of transmitting information about resources related to Channel State Information (CSI) to terminals, wherein said resources are configured based on resource information of a first cell different from the serving cell of said terminals; The step of receiving the CSI from each of the above terminals, wherein the CSI comprises i) a first Signal to Interference plus Noise Ratio (SINR) associated with the serving cell and ii) a second SINR associated with the serving cell and the first cell; and The method includes the step of transmitting a common message and private messages to the terminals based on a modulation and coding scheme (MCS); The above MCS is determined based on i) a third SINR associated with the above common message and ii) a fourth SINR associated with each of the above private messages, and Among the above terminals, the first terminals affected by interference by the first cell are determined based on the CSI, and A method characterized by determining i) the third SINR and ii) the fourth SINR based on optimization for compensation of the interference above.

2. In Paragraph 1, A method characterized in that the above common message and the above private message are generated based on Rate Splitting Multiple Access (RSMA).

3. In Paragraph 1, A method characterized in that the first terminals include a terminal among the terminals in which the second SINR is smaller than the first SINR.

4. In Paragraph 1, A method characterized in that the first cell is associated with a RIS (Reconfigurable intelligent surface).

5. In Paragraph 1, A method characterized by determining, based on the above optimization related to Weighted Maximum Mean Square Error (WMMSE), i) a first ratio related to the allocation of the common message to each of the first terminals, ii) a first precoding vector related to the common message, and iii) a second precoding vector related to the private message to each of the first terminals.

6. In Paragraph 5, A method characterized in that the above optimization is performed such that a weighted sum based on i) the common message rate of each of the first terminals and ii) the private message rate of each of the first terminals is maximized.

7. In Paragraph 5, The above third SINR and the above fourth SINR are determined based on i) a ratio associated with the terminals and ii) a precoding vector associated with the terminals, and The ratio related to the above terminals includes i) the first ratio and ii) a ratio related to the allocation of the common message to each of the remaining terminals excluding the first terminals, and A method characterized in that the precoding vector associated with the above terminals includes i) the first precoding vector, ii) the second precoding vector, and ii) the precoding vector associated with a private message for each of the remaining terminals.

8. Regarding base stations, One or more transmitters / receivers; One or more processors controlling the above one or more transceivers; and It includes one or more memories connected to the above one or more processors and storing instructions, A base station characterized by the above instructions, based on execution by the one or more processors, having the base station perform all steps of the method according to any one of claims 1 to 7.

9. An apparatus comprising one or more memories and one or more processors functionally connected to the one or more memories, An apparatus characterized in that the above one or more memories store instructions that cause the apparatus to perform all steps of the method according to any one of claims 1 to 7, based on execution by the above one or more processors.

10. In one or more non-transitory computer-readable media storing instructions, One or more non-transitory computer-readable media characterized by instructions executable by one or more processors that cause a base station to perform all steps of the method according to any one of claims 1 to 7.

11. Regarding the method, A step of receiving information about resources related to Channel State Information (CSI) from a base station, wherein said resources are set based on resource information of a serving cell and a first cell other than the serving cell; A step of transmitting the CSI to the base station, wherein the CSI comprises i) a first Signal to Interference plus Noise Ratio (SINR) associated with the serving cell and ii) a second SINR associated with the serving cell and the first cell; and The method includes the step of receiving a common message and a private message from the base station based on a modulation and coding scheme (MCS); The above MCS is determined based on i) a third SINR associated with the above common message and ii) a fourth SINR associated with each of the private messages, and A method characterized by determining i) the third SINR and ii) the fourth SINR based on optimization for compensation of interference by the first cell.

12. In the terminal, One or more transmitters / receivers; One or more processors controlling the above one or more transceivers; and It includes one or more memories connected to the above one or more processors and storing instructions, A terminal characterized by the above instructions enabling the terminal to perform all steps of the method according to claim 11 based on execution by the one or more processors.

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