US-20260128770-A1 - RIS-ADDED MULTI-INPUT MULTI-OUTPUT SYSTEM AND METHOD FOR CHANNEL ESTIMATION AND BEAMFORMING

US20260128770A1US 20260128770 A1US20260128770 A1US 20260128770A1US-20260128770-A1

Abstract

According to an embodiment of the disclosed invention, a beamforming method of a wireless communication system including a base station, a reconfigurable intelligent surface, and a plurality of user equipment comprises: acquiring channel information between the base station and the reconfigurable intelligent surface; determining a phase change value input to the reconfigurable intelligent surface; and estimating a dependent channel based on the channel information, the phase change value, and an Lth column vector of an effective channel collected from the user equipment.

Inventors

Song Nam HONG
Jeong Jae LEE

Assignees

IUCF-HYU (INDUSTRY-UNIVERSITY COOPERATION FOUNDATION HANYANG UNIVERSITY)

Dates

Publication Date: 20260507
Application Date: 20251030
Priority Date: 20241105

Claims (8)

1 . A beamforming method of a wireless communication system including a base station, a reconfigurable intelligent surface, and a plurality of user equipment, comprising: acquiring channel information between the base station and the reconfigurable intelligent surface; determining a phase change value input to the reconfigurable intelligent surface; and estimating a dependent channel based on the channel information, the phase change value, and an Lth column vector of an effective channel collected from the user equipment.
2 . The beamforming method according to claim 1 , further comprising: performing a Kronecker product based on a preset constant value and the phase change value.
3 . The beamforming method according to claim 2 , wherein estimating the dependent channel comprises: calculating a diagonal matrix value based on the Lth column vector of the effective channel; and calculating effective channels of the plurality of user equipment based on the diagonal matrix value and the channel information.
4 . The beamforming method according to claim 3 , further comprising: performing hybrid beamforming based on the estimated dependent channel.
5 . A wireless communication system comprising: a reconfigurable intelligent surface; a base station configured to transmit and receive signals with the reconfigurable intelligent surface; and a plurality of user equipment configured to transmit and receive signals with the reconfigurable intelligent surface, wherein the base station: acquires channel information between the base station and the reconfigurable intelligent surface, determines a phase change value input to the reconfigurable intelligent surface, and estimates a dependent channel based on first channel information, the phase change value, and an Lth column vector of an effective channel collected from the user equipment.
6 . The wireless communication system according to claim 5 , wherein the base station performs a Kronecker product based on a preset constant value and the phase change value.
7 . The wireless communication system according to claim 6 , wherein the base station: calculates a diagonal matrix value based on the Lth column vector of the effective channel, and calculates effective channels of the plurality of user equipment based on the diagonal matrix value and the channel information.
8 . The wireless communication system according to claim 7 , wherein the base station performs hybrid beamforming based on the estimated dependent channel.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority under 35 U.S.C § 119 to Korean Patent Application No. 10-2024-0155630 filed on Nov. 5, 2024, in the Korean Intellectual Property Office, the entire contents of which are hereby incorporated by reference. TECHNICAL FIELD The disclosed embodiment relates to a RIS-added multi-input multi-output system including a reconfigurable intelligent surface (RIS), which is configured to estimate a dependent wireless channel based on a low rank and perform hybrid beamforming suitable therefor. BACKGROUND Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcast, or other similar types of devices. Such wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (for example, bandwidth, transmission power, or other resources). Examples of multiple-access technologies may rely on any of code division, time division, frequency division, orthogonal frequency division, single-carrier frequency division, or time division synchronous code division. These and other multiple-access technologies have been adopted in various communication standards to provide a common protocol that enables different wireless devices to communicate at city, national, regional, and even global levels. Although wireless communication systems have achieved technological advancements over the years, challenges still remain to be solved. For example, complex and dynamic environments still attenuate or block signals between wireless transmitters and wireless receivers. For this purpose, research on various channel estimation and reporting mechanisms is required. Among them, hybrid beamforming technology, which is used to manage and optimize the use of finite wireless channel resources, has been studied; however, there has been a limitation in that it is practically impossible to obtain dependent wireless channel information suitable for 6G communication. Here, the channel to be estimated with the assistance of a reconfigurable intelligent surface (RIS) is referred to as a dependent channel, and a new multi-input multi-output channel different from a conventional multi-input multi-output channel has become necessary. Conventionally, by using a compressed sensing algorithm through the sparsity of the dependent channel, channel estimation was efficiently performed, and a technology for optimizing hybrid beamforming suitable therefor was proposed. However, as the size of wireless communication systems continues to increase and the conventional channel estimation methods fail to exhibit good performance in 6G communication, there has arisen a need for a new technology. Meanwhile, in order to secure a higher data transmission rate than that of 5G communication, 6G communication needs to increase frequency and bandwidth. Since radio waves in a high-frequency band are highly directional by nature, when there is a blockage in between, there has been a problem in that the radio waves are not well transmitted to a receiving end. SUMMARY According to an embodiment of the disclosed invention, the present disclosure relates to a multi-input multi-output system and a method for channel estimation and beamforming, which estimate a newly defined dependent channel in addition to a conventional channel estimation method and perform hybrid beamforming optimization through the estimation. A multi-input multi-output system and a method for channel estimation and beamforming according to an embodiment of the disclosed invention estimate a newly defined dependent channel in addition to a conventional channel estimation method and perform hybrid beamforming optimization through the estimation. Through this, the multi-input multi-output system and the method for channel estimation and beamforming according to an embodiment of the disclosed invention simplify existing hybrid beamforming technology and enable a more practical system configuration at the same time. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining an example of a wireless communication system according to an embodiment of the disclosed invention. FIG. 2 is a block diagram of a base station and a user equipment according to an embodiment of the disclosed invention. FIG. 3 is a flowchart for explaining a disclosed beamforming method. FIG. 4 is a diagram for explaining an embodiment in which the disclosed wireless communication system reduces training overhead and computational complexity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining an example of a wireless communication system according to an embodiment of the disclosed invention. Referring to FIG. 1, a wireless communication system 1 according to the disclosed invention may include a base station (BS) 10, a user equipment (UE) 20, and a reconfigu