KR102854557B1 - Method and apparatus for transmitting and receiving signal in a wireless communication system - Google Patents

Abstract

The present disclosure relates to a method and device for transmitting and receiving a signal in a wireless communication system, wherein the electronic device in the wireless communication system includes a transceiver; and at least one processor; wherein the transceiver includes an antenna unit and a metasurface unit, the antenna unit includes a plurality of antennas, and the at least one processor generates first beams for each of the plurality of antennas, transmits the first beams from the plurality of antennas to the metasurface unit, generates second beams based on the first beams through the metasurface unit, and transmits the second beams to another electronic device, and the metasurface unit can be arranged to receive the first beams generated for each of the plurality of antennas.

Description

METHOD AND APPARATUS FOR TRANSMITTING AND RECEIVING SIGNAL IN A WIRELESS COMMUNICATION SYSTEM

The present disclosure relates to a method and device for transmitting and receiving a signal in a wireless communication system.

In the ^6th generation (6G) mobile communication system following 5G ( ^5th generation), ultra-high frequency bands such as millimeter wave (MW) or terahertz (THz) bands may be utilized to secure insufficient bandwidth. In the UHF band, the loss due to path loss of radio waves is large, and the amplitude of reflected or transmitted radio waves can drop sharply compared to the previous mobile communication frequencies (frequencies below 6 GHz, such as UHF (Ultra High Frequency) and VHF (Very High Frequency) bands). To mitigate this path loss of radio waves and increase the reception range of radio waves, beamforming (hereinafter, beamforming) techniques utilizing multiple antennas may be utilized. A terminal or base station can also direct a beam in a specific direction using analog and digital signal processing techniques in addition to multiple antennas. However, to adjust the beam's direction angle, additional high-frequency signal processing components such as a phase shifter, a power amplifier, and a mixer are required. These high-frequency signal processing components themselves consume power. Consequently, as the number of high-frequency signal processing components per antenna increases, additional energy consumption for beamforming and beam directing can arise. Consequently, research into metamaterials is underway.

Based on the discussion described above, the present disclosure provides a device and method capable of effectively transmitting and receiving signals in a wireless communication system.

According to one embodiment of the present disclosure, in a wireless communication system, an electronic device includes a transceiver; and at least one processor; wherein the transceiver includes an antenna unit and a metasurface unit, the antenna unit includes a plurality of antennas, and the at least one processor generates first beams for each of the plurality of antennas, transmits the first beams from the plurality of antennas to the metasurface unit, generates second beams based on the first beams through the metasurface unit, and transmits the second beams to another electronic device, and the metasurface unit can be arranged to receive the first beams generated for each of the plurality of antennas.

Alternatively, according to one embodiment of the present disclosure, a method of operating an electronic device in a wireless communication system may include: generating first beams for each of a plurality of antennas; transmitting the first beams from the plurality of antennas to a metasurface unit; generating second beams based on the first beams through the metasurface unit; and transmitting the second beams to another electronic device; wherein the metasurface unit may be arranged to receive the first beams generated for each of the plurality of antennas.

Figure 1 is a diagram illustrating an example of reflection and refraction associated with a metasurface.
Figure 2 is a diagram illustrating two examples of metasurface utilization.
FIG. 3 is a diagram illustrating examples of phased array beamforming and metasurface beamforming.
FIG. 4 is a diagram illustrating examples of an optical lens-based radio frequency (RF) front-end structure and a single-layer metasurface RF front-end structure.
FIG. 5 is a diagram illustrating an example of a multi-layer metasurface RF front-end structure according to one embodiment of the present disclosure.
FIG. 6 is a diagram illustrating a specific example of a multi-layer metasurface RF front-end structure according to one embodiment of the present disclosure.
FIG. 7 is a diagram illustrating an example of a metasurface RF front-end structure according to one embodiment of the present disclosure.
FIG. 8 is a flowchart illustrating a method of operating an electronic device according to one embodiment of the present disclosure.
FIG. 9A is a diagram illustrating an example of linearly arrayed antennas on a metasurface according to one embodiment of the present disclosure.
FIG. 9b is a diagram illustrating the measurement results of beamforming gain for linearly arranged antennas on a metasurface according to one embodiment of the present disclosure.
FIG. 10A is a diagram illustrating an example of antennas arranged radially about a metasurface according to one embodiment of the present disclosure.
FIG. 10b is a diagram illustrating the measurement results of beamforming gain for antennas radially arranged with respect to a metasurface according to one embodiment of the present disclosure.
FIG. 11 is a diagram illustrating a system including a meta channel according to one embodiment of the present disclosure.
FIG. 12 is a diagram illustrating an example of a channel model using a metasurface according to one embodiment of the present disclosure.
FIG. 13 is a diagram illustrating the result of beamforming due to a metasurface according to one embodiment of the present disclosure.
FIG. 14 is a diagram illustrating a setup for measuring a radiation pattern using a metasurface according to one embodiment of the present disclosure.
FIG. 15 is a diagram illustrating beamforming gain of an antenna array and a metasurface according to one embodiment of the present disclosure.
FIG. 16A is a diagram illustrating the gain as a function of angle of a linear non-focal feed antenna according to one embodiment of the present disclosure.
FIG. 16b is a diagram illustrating the gain as a function of angle of a radial non-focal feed antenna according to one embodiment of the present disclosure.
FIG. 17 is a diagram illustrating an antenna pattern according to one embodiment of the present disclosure.
FIG. 18 is a diagram illustrating an average UE (user equipment) capacity due to a meta table according to one embodiment of the present disclosure.
FIG. 19 is a block diagram illustrating a configuration of an electronic device according to one embodiment of the present disclosure.
FIG. 20 is a block diagram illustrating a configuration of a transceiver unit of an electronic device according to one embodiment of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings. Furthermore, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Furthermore, the terms described below are defined based on their functions in the present disclosure and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the overall content of this specification.

The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided solely to ensure that the disclosure of the present disclosure is complete and to fully inform those skilled in the art of the scope of the invention, and the present disclosure is defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

At this time, it will be understood that each block of the processing flowchart drawings and combinations of the flowchart drawings can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flowchart block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flowchart block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

Here, the term '~ part' used in this embodiment means software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and the '~ part' performs certain roles. However, the '~ part' is not limited to software or hardware. The '~ part' may be configured to be on an addressable storage medium or may be configured to play one or more processors. Therefore, as an example, the '~ part' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and '~ parts' may be combined into a smaller number of components and '~ parts' or further separated into additional components and '~ parts'. Additionally, the components and '~parts' may be implemented to activate one or more CPUs within a device or secure multimedia card. Furthermore, in an embodiment, the '~part' may include one or more processors.

In the following description of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Hereinafter, embodiments of the present disclosure will be described with reference to the attached drawings.

The terms used in the following description to identify connection nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, terms referring to various identification information, etc. are provided as examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms referring to objects with equivalent technical meanings may be used.

In the following description, the terms "physical channel" and "signal" may be used interchangeably with data or control signals. For example, while PDSCH (physical downlink shared channel) refers to a physical channel through which data is transmitted, PDSCH can also be used to refer to data. That is, in the present disclosure, the expression "transmitting a physical channel" can be interpreted equivalently to the expression "transmitting data or a signal through a physical channel."

Hereinafter, in the present disclosure, upper signaling refers to a signal transmission method in which a base station transmits a signal to a terminal using a downlink data channel of the physical layer, or a terminal transmits a signal to a base station using an uplink data channel of the physical layer. Upper signaling can be understood as radio resource control (RRC) signaling or a media access control (MAC) control element (CE).

For the convenience of explanation below, this disclosure uses terms and names defined in the 3rd Generation Partnership Project NR (New Radio) standard. However, this disclosure is not limited by the above terms and names, and can be equally applied to systems conforming to other standards. In this disclosure, gNB may be used interchangeably with eNB for the convenience of explanation. That is, a base station described as an eNB may represent a gNB. In addition, the term terminal may refer to other wireless communication devices as well as mobile phones, MTC devices, NB-IoT devices, and sensors.

Hereinafter, the base station is an entity that performs resource allocation of a terminal, and may be at least one of a gNode B (gNB), an eNode B (eNB), a Node B, a BS (Base Station), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. Of course, the present invention is not limited to the above examples.

Generations of wireless communication systems are moving from microwave and millimeter wave (mmWave) frequencies to higher operating frequencies, such as the terahertz (THz) band, to meet the demands of soaring data rates. The 3GPP has included the 24, 26, 28, and 39 GHz bands in the 5G NR specification, which were not considered for 4G LTE systems. In particular, the terahertz band, which extends from 0.1 THz to 10 THz, has the potential to excavate approximately 200 GHz more bandwidth. Consequently, these high-frequency bands are attracting several companies in the wireless communications industry.

Despite the obvious advantages of high frequencies, there are challenges that must be addressed to use these higher bands in cellular networks compared to current bands, including:

1) Inefficient RF components: The terahertz (THz) band has long been underutilized due to the lack of efficient RF components. In particular, semiconductor processing technologies such as CMOS and SiGe have not been able to provide sufficient gain and efficiency for power amplifier (PA) development. The lack of practical RF components targeting the terahertz band, between the microwave and infrared regions, has created the so-called THz band gap.

2) High loss in RF transmission lines: In a typical transceiver, transmission lines are required to carry RF signals between RF components and antenna elements to radiate or receive signals. As frequencies increase, wavelengths become shorter, and thus more energy can be dissipated through the transmission lines. Without new transmission line designs for the terahertz band, antenna elements may not be able to receive enough power to radiate signals to manage the link budget.

3) High propagation attenuation: High-frequency electromagnetic waves can experience inherent free space path loss (FSPL), which is inversely proportional to the square of the frequency. For example, when comparing an operating frequency of 1.8 GHz with a THz frequency of 180 GHz, the FSPL is 40 dB higher than that of the LTE band, which can represent a significant attenuation of approximately 10,000 times. Environmental attenuation associated with operating at high frequencies can also increase. For example, the attenuation due to atmospheric absorption of a 60 GHz waveform can exceed 10 dB/km, while a 700 MHz waveform can experience an attenuation of approximately 0.01 dB/km. This high attenuation of electromagnetic waves can be considered a major obstacle to realizing terahertz communication systems.

To overcome the aforementioned challenges and fully utilize the high spectrum, highly efficient transmitters (TX) and receivers (RX) must be developed. Accordingly, several attempts have been made to utilize metamaterials, artificial substances with micro- or nanoscale structures capable of controlling electromagnetic waves in a desired manner.

An electromagnetically invisible cloak has been implemented using metamaterials designed to span the microwave band. Furthermore, a planar metamaterial composed of Jerusalem cross-shaped unit cells has been introduced to design a high-gain, low-profile lens antenna using phase-gradient metamaterials. Furthermore, a beamforming technique based on the use of metamaterials composed of phase-shift structures (PSSs) designed to reshape a primary beam into a desired beam has been introduced. The beam can be considered as a set of ray tubes, and their refractive properties can be modified by the PSSs based on the generalized laws of refraction to form a beam of a desired shape. Furthermore, high-gain directive beam patterns and the beam directivity of metamaterials are being studied. Additionally, metamaterial lens designs applying Huygens' principle have been studied to achieve desired lens effects while minimizing reflections and maintaining a low profile.

The existing metamaterial technology described above demonstrates that radiation from an embedded omnidirectional source can be converted into any desired number of highly directional beams directed in arbitrary directions. In particular, metasurfaces, which are planar metamaterial structures composed of unit cells such as split ring resonators or V-shaped antennas, can control wave propagation by refracting incident waves with low reflection or absorption loss.

Studies on metasurfaces have focused on how much beamforming gain can be achieved in single-layer transmission scenarios. However, these studies have not considered the efficiency of MIMO operation or its impact on baseband system design. In this regard, the present disclosure proposes a novel metasurface RF front-end design that enables MIMO operation using metasurfaces. Specifically, we demonstrate that a well-designed, large-aperture metasurface according to the present disclosure can achieve significant beamforming gain not only for a single feed antenna located at the focal point, but also for other feed antennas properly located at non-focal points.

Additionally, the RF front-end design proposed in this disclosure can achieve high system capacity and beamforming gain by appropriately utilizing the metasurface and antenna array. Therefore, the novel RF front-end design utilizing the metasurface of this disclosure can be used for future 6G wireless communications. In particular, when the RF front-end design according to this disclosure is introduced, problems related to device efficiency in high-frequency bands can be improved. Metamaterials applicable to embodiments of this disclosure are described below.

In the present disclosure, a metamaterial may refer to a material designed to induce specific electromagnetic properties due to the geometric characteristics of materials arranged in an artificial structure. In addition, a metasurface may collectively refer to an object made of a metamaterial in a two-dimensional planar structure. In communication systems, metasurfaces are being studied as components of lens antennas. Specifically, a metasurface can generate a phase difference in a radio wave incident on a unit cell of the metasurface by uniformly or non-uniformly arranging unit cells in a planar shape at a distance shorter than the wavelength of the radio wave emitted from the antenna. In addition, the metasurface can re-radiate the radio wave incident on the unit cell of the metasurface by utilizing this phase difference. Therefore, when the unit cells are designed and arranged at appropriate locations, a beam forming function that gathers the radio waves emitted from the antenna can be utilized, and the beam direction angle can be adjusted. Therefore, when a structure of a metamaterial surface that collects radio waves radiated from a specific antenna using a metasurface is designed, it can be utilized as a device that alleviates propagation path loss in a high frequency band. In this way, the device that alleviates propagation path loss in a high frequency band using a metamaterial surface in the present disclosure may be referred to as a metasurface, a metamaterial lens, or a metasurface lens. Hereinafter, it is referred to as a metasurface in the present disclosure. When a metasurface is used together with an antenna, a higher beam gain can be obtained than when the antenna alone is used.

Metamaterials are artificial substances with micro- or nanoscale structures that can control electromagnetic (EM) waves in a desired manner. Electromagnetic waves incident on a metasurface, a planar metamaterial structure, can experience different phase shifts depending on the subwavelength-scale unit cells. The phase shifts of a well-designed metasurface can lead to unprecedented beamforming gains. However, multi-input, multi-output (MIMO) operation schemes utilizing metasurfaces have not yet been discussed.

Accordingly, the present disclosure proposes a Radio Frequency (RF) front-end structure related to a MIMO operating system utilizing the metasurface described above. When the RF front-end structure according to the present disclosure is used, not only beamforming gain but also system capacity due to the metasurface can be increased. Furthermore, the metasurface according to the present disclosure can facilitate MIMO operation in a high frequency band for 6G wireless communications. First, the principle of the metasurface according to the present disclosure is explained with reference to FIGS. 1 and 2 described below.

Figure 1 is a diagram illustrating an example of reflection and refraction associated with a metasurface.

Referring to Fig. 1, the concept of a metasurface can be expressed through the laws of reflection and refraction. For example, in the case of the laws of refraction that can be applied to a metasurface, a one-dimensional metasurface has a negligible thickness below a critical value along the z-axis, and the unit cells of the metasurface are arranged along the x-axis. It can be assumed that the metasurface has a phase discontinuity. For example, the relationship between each parameter according to the law of refraction of the metasurface in Fig. 1 is as shown in <Mathematical Formula 1> below.

In <Mathematical Formula 1>, , , , may represent the angles and refractive indices of the transmitted and incident medium, respectively. For example, may refer to the transmitted angle or refraction angle for the anomalous refraction of electromagnetic waves traveling from the metasurface to the medium 2, can mean the incident angle of the electromagnetic wave traveling from medium 1 to the metasurface. And, can mean the refractive index of medium 2, can mean the refractive index of medium 1. Also, can mean the wavelength. In the absence of phase discontinuity introduced by the metasurface (i.e., ), the above-described <Mathematical Expression 1> can be identical to Snell's law of geometric optics. <Mathematical Expression 1> is the law of geometric optics in which the refracted wave is oriented in an arbitrary direction. It can be implied that there is a possibility of having a phase discontinuity gradient along the interface, as shown in Fig. 1. In addition, referring to Fig. 1, anomalous reflection can also occur for the incident electromagnetic wave traveling from medium 1 to the metasurface.

Discrete phase-discontinuous metasurfaces composed of single or multi-layer planar metamaterials can be realized by periodically printing sub-wavelength metallic unit cells onto a substrate. Each unit cell constituting the metasurface can receive an incident electromagnetic wave from a feed antenna element and subsequently radiate a phase-delayed electromagnetic wave.

According to the Huygens-Fresnel principle, equiphase wavefronts can be generated by constructively combining phase-delayed spherical waves from unit cells. By designing a metasurface that radiates equiphase wavefronts, such as so-called plane waves, the amplitude of the wave is preserved along the propagation direction, resulting in high beamforming gain.

Figure 2 is a diagram illustrating two examples of metasurface applications.

Referring to Fig. 2, the left picture of Fig. 2 shows that a spherical wave emitted from a feed antenna can be rearranged into a plane wave directed by the metasurface. This beam controllability can be attributed to unit cells with different phase offsets depending on the radial distance from the antenna to the focal axis through the center of the metasurface.

The right figure of Fig. 2 illustrates an example of a plane wave generated from a feed antenna array and the reverse phenomenon. For example, the metasurface in the right figure can generate a concentrated electromagnetic wave by adopting an opposite phase offset to the example in the left figure. To mitigate the intrinsic attenuation in the high-frequency band and to utilize the amplitude enhancement of collimated waves, cases ranging from dispersive spherical waves to concentrated plane waves can be studied. In addition, Fig. 2 shows graphs showing the radial distance according to the phase shift for the left and right figures, respectively.

FIG. 3 is a diagram illustrating examples of phased array beamforming and metasurface beamforming.

Referring to FIG. 3, examples of phased array beamforming (310) and metasurface beamforming (320) are illustrated. In the phased array beamforming (310), analog beamforming can be performed. That is, the beam direction can be controlled by adjusting the phase between a plurality of RF phase shifters. In addition, the phased array beamforming (310) can perform MIMO operation. Accordingly, a spatial multiplexing gain can be obtained. However, in the phased array beamforming (310), the structure of the RF front-end can be complicated due to the plurality of RF phase shifters, and the power consumption for operating the plurality of RF phase shifters can be high. That is, power consumption can occur for each antenna element. Accordingly, in the phased array beamforming (310), RF loss can occur when controlling the beam direction using the RF phase shifter.

Metasurface beamforming (320) has the advantage of enabling beamforming through a single antenna element. However, in the case of general metasurface beamforming, beam steering could not be performed and MIMO gain could not be obtained. Therefore, the present disclosure proposes a metasurface RF front-end structure that not only enables beam steering but also obtains efficient MIMO gain. Hereinafter, FIGS. 4 and 5 explain the differences between a metasurface structure having an optical lens or a single layer and the multi-layer metasurface structure proposed in the present disclosure.

FIG. 4 is a diagram illustrating examples of an optical lens-based radio frequency (RF) front-end structure and a single-layer metasurface RF front-end structure.

Referring to FIG. 4, an example of an optical lens-based RF front-end (410) structure and an example of a single-layer metasurface RF front-end (420) structure are illustrated.

In Fig. 4, the optical lens-based RF front-end (410) structure may include a feed line connecting a power amplifier (PA) and an antenna array, and an antenna array and an optical lens. In addition, the optical lens-based RF front-end (410) structure may include an optical lens antenna capable of focusing an electromagnetic wave to a designated point. The optical lens-based RF front-end (410) structure has the disadvantage of being bulky and non-flat because the optical lens requires focal distances between the antenna and the lens and a thickness for refracting rays.

In FIG. 4, a single-layer metasurface RF front-end (420) structure may include a power amplifier, an antenna array, and a metasurface. The single-layer metasurface RF front-end (420) structure represents a metasurface-antenna pair. Since the metasurface has a shorter focal length than an optical lens, it can be placed closer to the antenna array than the optical lens. However, in the single-layer metasurface RF front-end (420) structure of FIG. 4, only a single data stream can be transmitted for one metasurface-antenna pair, so the spatial multiplexing gain of the MIMO system cannot be achieved. Accordingly, the present disclosure proposes a multi-layer metasurface RF front-end structure in FIG. 5 to overcome the shortcomings of the optical lens-based RF front-end (410) structure and the single-layer metasurface RF front-end (420) structure illustrated in FIG. 4.

FIG. 5 is a diagram illustrating an example of a multi-layer metasurface RF front-end structure according to one embodiment of the present disclosure.

Referring to FIG. 5, the multi-layer metasurface RF front-end (500) system may be referred to as a MIMO metasurface RF front-end system. Accordingly, the MIMO metasurface RF front-end system may be composed of multiple feed antennas and a large-aperture metasurface that refracts all waves in a designated direction. That is, the multi-layer metasurface RF front-end (500) structure according to FIG. 5 may include a first antenna array (510), a second antenna array (520), and a third antenna array (530), in which precoding is performed for each layer (e.g., layer 1, layer 2, layer 3) and a signal whose power is amplified is input through a power amplifier (PA) of each port (e.g., port 1, port 2, port 3), and may include a metasurface (540) capable of receiving beams emitted from the first antenna array (510), the second antenna array (520), and the third antenna array (530), respectively. The metasurface (540) may form beams in a specific direction using the beams emitted from the first antenna array (510), the second antenna array (520), and the third antenna array (530), respectively. That is, multi-stream beamforming (550) can be performed through the metasurface (540). According to one embodiment, it can be considered that data streams are formed for each layer. That is, three data streams can be formed for three layers.

The multi-layer metasurface RF front-end (500) structure disclosed in FIG. 5 can have advantages such as 1) capability of MIMO operation, 2) higher beamforming gain through a large aperture, 3) capability of beam steering, and 4) small form factor compared to the optical lens antenna, compared to the optical lens-based RF front-end (410) structure and the single-layer metasurface RF front-end (420) structure illustrated in FIG. 4.

While research on metasurfaces has focused solely on the beamforming gain of a single antenna-single lens pair, embodiments according to the present disclosure propose a multi-antenna single metasurface structure that can achieve both enhanced beamforming gain and system capacity.

To illustrate the RF front-end design proposed in this disclosure, the geometry and parameters can be set as shown in Table 1. Furthermore, the parameters can be categorized into three groups, as shown in Table 1. For example, the three groups can be categorized into general parameters, parameters related to the feed antenna, and parameters related to the metasurface.

Referring to <Table 1>, in the general parameters, can mean frequency. can mean wavelength. can mean the distance from the antenna to the metasurface. can mean a channel matrix. can mean the number/index of multipath. can mean the number of sub-paths. may refer to the base station angular spread. may refer to the angular spread of MS (mobile station). can mean the Angle of departure (AoD), may mean Angle of arrival (AoA). can mean wavenumber.

Also, in the parameters related to the feed antenna, may mean the number/index of receiving antennas. may mean the number/index of transmitting antennas. may refer to the distance between BS antenna arrays. may refer to the distance between MS antenna arrays. may refer to the radiation pattern of a transmitting antenna. may refer to the radiation pattern of a receiving antenna.

Also, in the parameters related to the metasurface, may mean the number/index of RX meta elements. may mean the number/index of transmitted meta elements. can mean the number of meta elements. can mean the distance between meta elements. may refer to the radiation pattern of the transmitting meta element. may refer to the radiation pattern of the receiving meta element.

For geometric convenience, two-dimensional spatial channels for the antenna array and metasurface can be considered. Alternatively, the spatial channels for the antenna array and metasurface can be extended to three dimensions.

FIG. 6 is a diagram illustrating a specific example of a multi-layer metasurface RF front-end structure according to one embodiment of the present disclosure.

Referring to FIG. 6, the multi-layer metasurface RF front-end structure may include transmit antennas (610), and in the embodiment of FIG. 6, the transmit antennas (610) may include three transmit antennas (e.g., a first antenna (612), a second antenna (614), and a third antenna (616)). Each of these three antennas may form a radiation pattern. The direction of the main beam may be determined based on the radiation pattern for each antenna. However, although only three transmit antennas (610) are illustrated in FIG. 6, the present invention is not limited thereto. In one embodiment, the first antenna (612), the second antenna (614), and the third antenna (616) of FIG. 6 may correspond to the first antenna array (510), the second antenna array (520), and the third antenna array (530) of FIG. 5, respectively.

According to one embodiment, the multi-layer metasurface RF front-end structure according to the present disclosure may further include a plurality of transmit antennas. For example, the multi-layer metasurface RF front-end structure of FIG. 6 may include a fourth antenna (622), a fifth antenna (624), a sixth antenna (626), a seventh antenna (628), an eighth antenna (630), and a ninth antenna (632). In addition, each of the transmit antennas may include one or more antenna elements.

According to one embodiment, the antennas included in the transmitting antennas (610) may be arranged according to the spacing (640) between the antennas. And, the transmitting antennas (610) and the metasurface may be arranged according to the spacing (642) between the transmitting antennas (610) and the metasurface. And, the metasurface may include a plurality of unit cells. And, the plurality of unit cells included in the metasurface may be arranged according to the spacing (644) between the plurality of unit cells. According to one embodiment, the spacing (644) between the plurality of unit cells may be determined based on the spacing (640) between the antennas or the spacing (642) between the transmitting antennas (610) and the metasurface. In addition, the metasurface may be arranged symmetrically with respect to the center of the antenna array. For example, the distance (646) from the center of the antenna array to the end of the metasurface may be the same for the left and right sides of the metasurface from the center of the antenna array.

In one embodiment, when the number of transmit antennas increases, the distance (646) from the center of the antenna array to the end of the metasurface may increase to accommodate all beams formed by the increasing number of transmit antennas. That is, the size of the metasurface may increase. FIG. 7, described below, shows an example that generalizes the structure of antennas and the metasurface from the multi-layer metasurface RF front-end structure according to FIG. 5.

FIG. 7 is a diagram illustrating an example of a metasurface RF front-end structure according to one embodiment of the present disclosure.

Referring to FIG. 7, the metasurface RF front-end structure according to the present disclosure may be included in a transceiver section of an electronic device. In this case, the electronic device may refer to a terminal, a base station, or another communication node. Furthermore, in the present disclosure, both an antenna array and an antenna panel may be referred to as an antenna.

The metasurface RF front-end structure disclosed in FIG. 7 may include a first antenna (710), a second antenna (720), and a third antenna (730). However, the number of antennas included in the metasurface RF front-end structure according to the present disclosure is not limited to the number of antennas according to the present example. Each antenna may include one or more antenna elements. For example, a first antenna (710) may include a first antenna element (712), a second antenna element (714), a third antenna element (716), and a fourth antenna element (718), a second antenna (720) may include a fifth antenna element (722), a sixth antenna element (724), a seventh antenna element (726), and an eighth antenna element (728), and a third antenna (730) may include a ninth antenna element (732), a tenth antenna element (734), an eleventh antenna element (736), and a twelfth antenna element (738).

In one embodiment, a transmit beam may be formed for each of the plurality of antennas. For example, a first antenna (710) may form first beams (740), a second antenna (720) may form second beams (750), and a third antenna (730) may form third beams (760).

According to one embodiment, the metasurface (770) may include one or more unit cells. For example, the metasurface (770) may include a first unit cell (772) and a second unit cell (774). Additionally, the first unit cell (772) and the second unit cell (774) may be arranged at a specific interval (780).

According to one embodiment, the metasurface (770) can generate a transmission beam for transmission to another electronic device based on beams received from a plurality of antennas. For example, the metasurface (770) can generate beams (790) for transmission to another electronic device based on first beams (740) emitted from a first antenna (710), second beams (750) emitted from a second antenna (720), and third beams (760) emitted from a third antenna (730). In this case, the metasurface (770) can be arranged to accommodate all of the beams emitted from the plurality of antennas (e.g., the first beams (740), the second beams (750), and the third beams (760)). At this time, the size of the metasurface (770) may be large enough to accommodate all beams emitted from multiple antennas (e.g., first beams (740), second beams (750), and third beams (760)).

In the present disclosure, beam gain, beamforming gain, or gain may refer to the gain of beams (790) emitted through the metasurface (770) relative to beams (e.g., first beams (740), second beams (750), and third beams (760)) emitted from a plurality of antennas (e.g., first antenna (710), second antenna (720), and third antenna (730)).

When a metasurface RF front-end structure is formed as in Fig. 7, the operating method of the electronic device is as in Fig. 8 described below.

FIG. 8 is a flowchart illustrating a method of operating an electronic device according to one embodiment of the present disclosure.

Referring to FIG. 8, in step 801, the electronic device may generate first beams for each of the plurality of antennas. For example, the electronic device may generate a transmission beam using antenna elements included in the plurality of antennas. According to one embodiment, the electronic device may generate a beam through the antenna by considering the direction of the beam to be ultimately generated on the metasurface. Alternatively, the electronic device may emit an arbitrary beam through the antenna and generate a beam having a desired direction through preset control with respect to the metasurface.

In step 803, the electronic device can transmit first beams from the plurality of antennas to the metasurface portion. That is, the beams emitted from the plurality of antennas can be received by the metasurface portion. At this time, the metasurface portion can be arranged to receive all beams generated for each of the plurality of antennas. That is, the size of the metasurface portion can be determined to receive all beams generated for each of the plurality of antennas. In the present disclosure, the metasurface portion can mean a unit including a metasurface.

In step 805, the electronic device can generate second beams based on the first beams through the metasurface. For example, the electronic device can generate a phase difference of radio waves incident on the unit cells of the metasurface through the arrangement of the unit cells included in the metasurface. Then, the electronic device can re-radiate the radio waves incident on the unit cells of the metasurface using the generated phase difference. Through this, the electronic device can focus the beams radiated from the antenna through the metasurface in a specific direction. At this time, the beams formed in the metasurface can mean the second beams.

At step 807, the electronic device can transmit the second beams to another electronic device. For example, if the electronic device is a terminal, the electronic device can transmit a signal using the second beams to another terminal or a base station. Alternatively, if the electronic device is a base station, the electronic device can transmit a signal using the second beams to another base station or a terminal.

Figures 9a to 10b described below illustrate examples of two different non-focal feed antennas.

FIG. 9A is a diagram illustrating an example of linearly arrayed antennas on a metasurface according to one embodiment of the present disclosure.

Referring to FIG. 9A, a first antenna (910), a second antenna (920), a third antenna (930), and a fourth antenna (940) may be arranged on a metasurface (950). At this time, the first antenna (910), the second antenna (920), the third antenna (930), and the fourth antenna (940) may be arranged in series. For example, a line connecting the centers of the first antenna (910), the second antenna (920), the third antenna (930), and the fourth antenna (940) may be arranged parallel to the metasurface (950). In addition, the first antenna (910), the second antenna (920), the third antenna (930), and the fourth antenna (940) may be arranged at equal intervals. For example, the first antenna (910) and the second antenna (920) may be arranged at a first interval (902), the second antenna (920) and the third antenna (930) may be arranged at a second interval (904), and the third antenna (930) and the fourth antenna (940) may be arranged at a third interval (906).

In one embodiment, the distances from the first antenna (910), the second antenna (920), the third antenna (930), and the fourth antenna (940) to the center (960) of the metasurface may be different. In one embodiment, the first antenna (910) may radiate a beam parallel to the center (960) of the metasurface. In this case, the first antenna (910) may be referred to as a focal antenna. On the other hand, the second antenna (920), the third antenna (930), and the fourth antenna (940) may not be able to radiate a beam parallel to the center (960) of the metasurface. In this case, the second antenna (920), the third antenna (930), and the fourth antenna (940) may be referred to as non-focal antennas.

That is, FIG. 9A illustrates an embodiment in which each of a plurality of antennas (e.g., a first antenna (910), a second antenna (920), a third antenna (930), and a fourth antenna (940)) can be arranged parallel to a metasurface (950), and the distance from each of the plurality of antennas (e.g., a first antenna (910), a second antenna (920), a third antenna (930), and a fourth antenna (940)) to the center (960) of the metasurface is different. For antennas arranged linearly with respect to the metasurface (950) as in FIG. 9A described above, the measured beamforming gain is illustrated in FIG. 9B described below.

FIG. 9b is a diagram illustrating the measurement results of beamforming gain for linearly arranged antennas on a metasurface according to one embodiment of the present disclosure.

Referring to FIG. 9B, the antenna of FIG. 9B may include a plurality of antennas. At this time, the first antenna, the second antenna, the third antenna, and the fourth antenna included in the antenna of FIG. 9B may correspond to the first antenna (910), the second antenna (920), the third antenna (930), and the fourth antenna (940) of FIG. 9A, respectively. In addition, the intervals between the respective antennas of FIG. 9B may correspond to the intervals (e.g., the first interval (902), the second interval (904), and the third interval (906)) of FIG. 9A, respectively. In addition, the metasurface of FIG. 9B may correspond to the metasurface (950) of FIG. 9A. FIG. 9B shows the beam gain of the metasurface compared to the antennas according to the position from the first antenna, which is a focus antenna, when the first antenna, the second antenna, the third antenna, and the fourth antenna radiate beams to the center of the metasurface.

In Fig. 9b, antennas 1, 2, 3 and 4 are respectively can be arranged with a sweeping angle of . That is, antennas 1, 2, 3, and 4 of Fig. 9b can be arranged with an interval of 1 cm. In this case, 1 cm is for the 28 GHz band. It can mean a value similar to the length of . That is, Fig. 9b For antennas spaced apart, the gain of the beam emitted through the metasurface is represented relative to the beam emitted through the antenna, depending on the position of each antenna from a parallel line passing through the center of the metasurface.

In the experiment illustrated in Fig. 9b, the aperture is limited and the metasurface may contain a small number of unit cells. However, the experimental results in Fig. 9b indicate that electromagnetic waves radiating from the positions of non-focused feed antennas (e.g., antennas 2, 3, and 4) also have significant beam gain and beam steering effects.

FIG. 10A is a diagram illustrating an example of antennas arranged radially about a metasurface according to one embodiment of the present disclosure.

Referring to FIG. 10A, a first antenna (1010), a second antenna (1020), a third antenna (1030), and a fourth antenna (1040) may be arranged on a metasurface (1050). At this time, the first antenna (1010), the second antenna (1020), the third antenna (1030), and the fourth antenna (1040) may be arranged radially. For example, a line connecting the respective centers of the first antenna (1010), the second antenna (1020), the third antenna (1030), and the fourth antenna (1040) may form a circle (1070), and the center of the circle (1070) may be the center (1060) of the metasurface.

Additionally, the first antenna (1010), the second antenna (1020), the third antenna (1030) and the fourth antenna (1040) may be arranged at the same angle. For example, the first antenna (1010) and the second antenna (1020) can be arranged, and the second antenna (1020) and the third antenna (1030) can be arranged as a third antenna (1030) and a fourth antenna (1040) can be deployed as

In one embodiment, the first antenna (1010) may radiate a beam parallel to the center (1060) of the metasurface. In this case, the first antenna (1010) may be referred to as a focusing antenna. On the other hand, the second antenna (1020), the third antenna (1030), and the fourth antenna (1040) may not be able to radiate a beam parallel to the center (1060) of the metasurface. In this case, the second antenna (1020), the third antenna (1030), and the fourth antenna (1040) may be referred to as non-focusing antennas.

That is, FIG. 10A illustrates an embodiment in which each of a plurality of antennas (e.g., a first antenna (1010), a second antenna (1020), a third antenna (1030), and a fourth antenna (1040)) may be arranged radially or circularly with respect to a metasurface (1050), and the distance from each of the plurality of antennas (e.g., a first antenna (1010), a second antenna (1020), a third antenna (1030), and a fourth antenna (1040)) to the center (1060) of the metasurface is equal to the radius of a circle (1070). For antennas arranged circularly with respect to the metasurface (1070) as in FIG. 10A described above, the measured beamforming gain is illustrated in FIG. 10B described below.

FIG. 10b is a diagram illustrating the measurement results of beamforming gain for antennas radially arranged with respect to a metasurface according to one embodiment of the present disclosure.

Referring to Fig. 10b, the antenna of Fig. 10b may include a plurality of antennas. At this time, the first antenna, the second antenna, the third antenna, and the fourth antenna included in the antenna of Fig. 10b may correspond to the first antenna (1010), the second antenna (1020), the third antenna (1030), and the fourth antenna (1040) of Fig. 10a, respectively. In addition, the metasurface of Fig. 10b may correspond to the metasurface (1050) of Fig. 10a. Fig. 10b shows the beam gain of the metasurface compared to the antenna according to the angle from the first antenna, which is a focus antenna, when the first antenna, the second antenna, the third antenna, and the fourth antenna radiate beams toward the center of the metasurface.

In Fig. 10b, the distance between the center of the metasurface and the feed antenna can be fixed to a focal distance of 2 cm. However, the angles of the antennas with respect to the axis perpendicular to the metasurface can be different. In one embodiment, the axis perpendicular to the metasurface can mean the axis connecting the center of the metasurface and the focal antenna (e.g., antenna 1). For example, the angle of antenna 1 from the axis perpendicular to the metasurface is , and the angle of the second antenna from the axis perpendicular to the metasurface is , and the angle of the third antenna from the axis perpendicular to the metasurface is , and the angle of the 4th antenna from the axis perpendicular to the metasurface is It could be.

According to one embodiment, the reason why the feed antennas are radially arranged as in FIG. 10b is because the signal attenuation from the feed antenna to the metasurface is proportional to the distance between the feed antenna and the metasurface. That is, since the signal attenuation from the feed antenna to the metasurface is proportional to the distance between the feed antenna and the metasurface, the radially arranged antennas of FIGS. 10a and 10b can obtain more gain compared to the linearly arranged antennas described in FIGS. 9a and 9b.

As illustrated in FIGS. 9b and 10b, electromagnetic waves radiating from a non-focus antenna location can experience significant beamforming gain and beam steering capability with the metasurface designed for a focal point. In one embodiment, to fully utilize the beamforming gain of the metasurface considering MIMO operation, the size of the aperture and the number of unit cells can be relatively small. For this reason, other metasurfaces with large apertures, physically reasonable domains, and densely integrated unit cells can be modeled. In this case, in the metachannel models described below, and Based on the metasurface design expressed in , the radiation patterns shown in FIGS. 9b and 10b can be used.

The present disclosure proposes channel modeling using metasurfaces. Since the metasurface according to the present disclosure can intervene between transmitter (Tx) and receiver (Rx) antennas, existing spatial channel models need to be modified to evaluate the overall performance of a wireless communication system using a structure such as that illustrated in FIG. 5 described above. In general, MIMO spatial channel models can be used to simulate wireless propagation channels in various environments and to apply the concept of diversity to multiple antennas at both the transmitter and receiver.

Despite research on metasurfaces, these studies have focused solely on the beamforming gains of metasurfaces themselves, and no research has been conducted to integrate spatial channel models with metasurface beamforming. In particular, metasurface structures have been considered only for single-layer transmission, posing fundamental limitations to their use. This is not appropriate for the trend toward utilizing spatial multiplexing gains by transmitting multiple data sets.

Accordingly, the present disclosure proposes integrating a metasurface RF front-end structure with MIMO operations. For example, the present disclosure proposes a full-space channel model called a metachannel. Figure 11, described below, illustrates the concept of a metachannel that can be formed according to the present disclosure.

FIG. 11 is a diagram illustrating a system including a meta channel according to one embodiment of the present disclosure.

Referring to FIG. 11, a system including a metachannel may include a transmitting device and a receiving device. In one embodiment, the transmitting device may include transmitting antennas (e.g., a first antenna (1102), a second antenna (1104), and a third antenna (1106)) and a metasurface. In this case, a first channel (1120) may be formed between the transmitting antennas and the metasurface.

And, such a metasurface may include unit cells (e.g., a first unit cell (1122), a second unit cell (1124), a third unit cell (1126), and a fourth unit cell (1128)). And, in the transmitting device, the second antenna (1104) may radiate beams to the unit cells of the metasurface. At this time, the beams may include a first beam (1112), a second beam (1114), a third beam (1116), and a fourth beam (1118). However, in FIG. 11, only the second antenna (1104) is illustrated as radiating beams, but this is not limited thereto. That is, the first antenna (1102) or the third antenna (1106) may also radiate beams.

In one embodiment, the receiving device may include receiving antennas (e.g., a fourth antenna (1152), a fifth antenna (1154), and a sixth antenna (1156)) and a metasurface. A second channel (1150) may be formed between the metasurface of the receiving device and the receiving antennas.

And, this metasurface may include unit cells (e.g., a fifth unit cell (1132), a sixth unit cell (1134), a seventh unit cell (1136), and an eighth unit cell (138)). And, beams may be transmitted from the metasurface to a fifth antenna (1154) in a receiving device. At this time, the beams may include a fifth beam (1142), a sixth beam (1144), a seventh beam (1146), and an eighth beam (1148). However, in FIG. 11, only the fifth antenna (1154) is illustrated as receiving the beams, but this is not limited thereto. That is, the fourth antenna (1152) or the sixth antenna (1156) may also receive the beams.

According to one embodiment, a meta-channel (1130) may be formed between a meta-surface of a transmitting device and a meta-surface of a receiving device. According to one embodiment, the meta-channel may be determined based on a departure angle or an arrival angle determined between each of a plurality of antenna elements and each of a plurality of unit cells, and a distance between each of a plurality of antenna elements and each of a plurality of unit cells.

In one embodiment, the departure angle determined between each of the plurality of antenna elements and each of the plurality of unit cells may mean a departure angle determined between each of the plurality of antenna elements included in the second antenna (1104) and each of the plurality of unit cells included in the meta surface of the transmitting device (e.g., the first unit cell (1122), the second unit cell (1124), the third unit cell (1126), and the fourth unit cell (1128)).

In one embodiment, the arrival angle determined between each of the plurality of antenna elements and each of the plurality of unit cells may mean the arrival angle determined between each of the plurality of unit cells (e.g., the fifth unit cell (1132), the sixth unit cell (1134), the seventh unit cell (1136), and the eighth unit cell (138)) included in the meta surface of the receiving device and each of the plurality of antenna elements included in the fifth antenna (1154).

In one embodiment, the radiation patterns of the plurality of antenna elements can be determined based on departure angles or arrival angles. Furthermore, the channel between the plurality of antennas and the metasurface can be determined based on the radiation patterns of the plurality of antenna elements.

FIG. 12 is a diagram illustrating an example of a channel model using a metasurface according to one embodiment of the present disclosure.

Referring to Fig. 12, a metachannel may be composed of three stages. For example, the three stages may include: 1) a first stage from a transmitting antenna to a transmitting metaelement (unit cell), 2) a second stage from a transmitting metaelement to a receiving metaelement, and 3) a third stage from a receiving metaelement to a receiving antenna. This cascading channel modeling may be essential and important because the beamforming gain and beam direction of the metasurface RF front-end structure may be completely different from geometric parameters such as the distance between the metasurface and the antenna, the position of the feed antenna, and the metaelement spacing. Fig. 12(a) illustrates a metachannel without a metasurface or when the metasurface is omitted, and Fig. 12(b) illustrates a configuration of a metachannel when a transmitting metasurface and a receiving metasurface are included.

Furthermore, from a practical point of view, the overall structures with and without metasurfaces on both the transmitter and receiver need to be individually considered in system design. In one embodiment, the metasurfaces on the transmitter and receiver may have different specifications. For example, the metasurface on the transmitter for the base station (BS) may need to have a larger aperture size to be more eligible for wider coverage. However, the metasurface on the mobile station (MS) may need to consider a wide beamwidth or diverse beam steering to eliminate blind spots.

In one embodiment, an important factor related to the metachannel may be whether the metasurface achieves sufficient gain compared to the general phased antenna array gain without the metasurface. Accordingly, in order to figure out the detailed impact of the metasurface RF front-end, a general metasurface-based MIMO channel model needs to be clearly defined, and each scenario needs to be classified based on the channel model. Accordingly, in the present disclosure, the entire channel matrix is as shown in <Mathematical Formula 2> below.

In <Mathematical Formula 2>, is excess delay This may refer to the nth multipath channel matrix that occurs. The elements of the channel matrix may be represented as a metasurface and an antenna-wise Tx-Rx pair. In one embodiment, the metachannel may be defined as in <Mathematical Formula 3> below.

Additionally, the spatial meta channel from the transmitter (Tx) antenna element s to the receiver (Rx) antenna element u can be defined as in <Mathematical Equation 4> below.

In <Mathematical Formula 4> , , may mean the number of unit cells of the receiver (Rx) and transmitter (Tx), respectively, and the sub-path of multipath n. In addition, , , and may respectively refer to the radiation patterns of the transmitter antenna, the transmitter unit cell, the receiver unit cell, and the receiver antenna. In one embodiment, each antenna and metasurface element may have different radiation patterns depending on its location. In particular, the unit cells may have different phase characteristics to compensate for the phase difference of the electromagnetic wave emanating from the feed antenna, such that the refracted waves are composed of plane waves in a certain direction. and may each mean the angle of departure (AoD) and the angle of arrival (AoA) of the m-th sub-path in the n-th multipath. can mean wavenumber. And, , , , can mean distances to each element.

According to one embodiment, all distances between antenna elements and unit cells, and pairwise distances between antenna elements and unit cells, can be measured in units of wavelengths, as specified in Table 1. However, because spatial channel models assume far-field propagation which extend from a few hundred of meters up to several kilometers, the distance between the metasurface and a cluster (or clutter) can be measured in units of meters. Based on the channel model described above, the system capacity can be analyzed through spatial channel modeling based on the structure illustrated in FIG. 5.

According to one embodiment, a scalable and analytical investigation can be performed to describe the design parameters and overall impacts of metasurfaces for multi-feed antennas via the metachannel proposed in the present disclosure.

Referring to Fig. 12, a channel is formed between the transmitting antennas and the transmitting metasurface. can be formed. At this time, the channel may refer to the first channel (1120) of Fig. 11. The channel between the transmitting antennas and the transmitting metasurface may be expressed as in <Mathematical Formula 5> below.

Additionally, a channel is formed between the transmitting metasurface and the receiving metasurface. can be formed. At this time, the channel may refer to the meta channel (1130) of Fig. 11. The channel between the transmitting meta surface and the receiving meta surface can be expressed as in <Mathematical Formula 6> below.

Additionally, a channel is formed between the receiving metasurface and the receiving antennas. can be formed. At this time, the channel may refer to the second channel (1150) of Fig. 11. The channel between the receiving metasurface and the receiving antennas may be expressed as in <Mathematical Formula 7> below.

Also, the entire channel from the transmitting antennas to the receiving antennas is can be expressed as . At this time, the entire channel is may refer to a cascading channel composed of the first channel (1120), the meta channel (1130), and the second channel (1150) of Fig. 11. The entire channel from the transmitting antennas to the receiving antennas can be expressed as in <Mathematical Formula 8> below.

FIG. 13 is a diagram illustrating the result of beamforming due to a metasurface according to one embodiment of the present disclosure.

Figure 13 illustrates the beamforming effect of a metasurface compared to an antenna array design. The metasurface can receive electromagnetic waves from antenna arrays and radiate them with predetermined phase delays. The phase-delayed electromagnetic waves can constructively interfere with each other to provide a higher beamforming gain in a desired direction. This beamforming gain is determined by the far-field radiation patterns of the transmitting metasurface and the receiving metasurface. and , respectively. Referring to Fig. 13, it can be confirmed that a higher beamforming gain is obtained in a structure in which an antenna and a metasurface exist together than when only an antenna exists.

In one embodiment, when the metasurface design is fixed, the composite radiation pattern of the metasurface-feed antenna pair can be determined by design parameters such as the radiation pattern, the positions of the feed antennas, and the metaelement characteristics.

According to one embodiment, the distance between the antenna and the metasurface, the number of metasurface elements, the metasurface, and the phase characteristics can be determined. Accordingly, the spatial metachannel from the transmitting antenna s of the above-described <Mathematical Formula 4> to the receiving antenna u can be simplified as in <Mathematical Formula 9> below.

In <Equation 9>, and may refer to a composite radiation pattern from designated antenna-metasurface pairs of a transmitter and a receiver, respectively.

FIG. 14 is a diagram illustrating a setup for measuring a radiation pattern using a metasurface according to one embodiment of the present disclosure.

Referring to Fig. 14, a metasurface RF front-end prototype can be designed and implemented to verify the feasibility of the metasurface with a fixed antenna array. Accordingly, Fig. 14 shows schematics of the measurement setup in the above-described prototype. The schematic of Fig. 14 may include a feed antenna, a metasurface, a jig, a horn antenna, and a rotator.

To verify the feasibility, the prototype metasurface can be positioned 2 cm away from a feed dipole antenna with a gain of 1.6 dBi. In addition, a horn antenna can be positioned 25 cm away from the prototype metasurface to measure the S21 parameters using a vector network analyzer (Anritsu MS46122A). The aperture size of the prototype metasurface is 28 50.4mm consisting of 28 size unit cells It can be 50.4 mm. The center frequency can be set to 28 GHz.

As described above in Figure 4, the lens antenna or single-layer metasurface is designed with a single focus to increase beamforming gain. However, in addition to a single focus, there may be a focal plane, a plane perpendicular to the axis of a lens, which may pass through the focus. An antenna located in the focal plane can achieve beamforming gain similar to that of the metasurface.

As described above in FIG. 5, multiple antennas can be arranged in the focal plane to obtain beamforming gain with a large aperture metasurface. Various simulations can be performed to estimate geometric parameters such as the number of antennas and unit cells, the distance between the antennas and the metasurface, and the antenna and unit cell spacing. FIGS. 15 to 18 described below demonstrate the possibilities of the MIMO metasurface RF front-end according to the present disclosure, and therefore, the values illustrated in FIGS. 15 to 18 are merely examples. Depending on various design factors such as the feed antenna characteristics or the amplitude and phase offset of the metasurface, the metasurface RF front-end design may have better characteristics.

FIG. 15 is a diagram illustrating beamforming gain of an antenna array and a metasurface according to one embodiment of the present disclosure.

Figure 15 shows the radiation pattern and gain of an antenna array having different numbers of antennas, The radiation pattern and gain of a metasurface with a single feed antenna positioned at intervals are shown. Referring to Fig. 5, the metasurface can obtain more beamforming gain compared to the antenna array pattern. In the results shown in Fig. 15, the metasurface It can be composed of 151 unit cells that are uniformly spaced. Each unit cell can have a different phase offset value to form an equiphase plane wave from the square wave of the feed antenna. In the embodiment of Fig. 15, the antenna array is can be separated. In Fig. 15, the radiation pattern of a single antenna is shown when N = 1, and the beam gain is 0 dB at this time. Also, the radiation pattern of the antenna is shown when N = 5, and the beam gain for boresight is 14.5 dB at this time. On the other hand, the metasurface design according to the present disclosure can have a beam gain of 22.9 dB. This is 8.4 dB higher than the beam gain of the antenna when N = 5.

An antenna array can transmit the same co-phased signal to achieve beam gain by simultaneously utilizing multiple antenna elements. However, the structure using the metasurface according to the present disclosure requires only a single antenna, and can achieve greater beamforming gain depending on the aperture size of the metasurface.

In contrast, the antenna array design according to the present disclosure can achieve a narrow beam width and parasitic high side lobes, compared to a relatively wide beam width and less severe side lobes. This result can be attributed to the design of the metasurface consisting of uniformly-spaced unit cells with phase compensations.

In one embodiment, the radiation pattern of the feed antenna may be initially set to radiate a square wave from a single point.

By utilizing different feed antenna designs and patterns, the results of the metasurface antenna pair can be more diverse. Therefore, the metasurface front-end design can be further improved by jointly designing both the feed antenna and the metasurface unit cells. The results shown in Figures 16a and 16b, described below, illustrate the beamforming gain at different antenna locations.

FIG. 16A is a diagram illustrating the gain as a function of angle of a linear non-focal feed antenna according to one embodiment of the present disclosure.

Referring to Figure 16a, it is shown that antennas positioned off-focus have similar beamforming gains to antennas positioned on-focus. This may indicate the effectiveness of the metasurface RF front-end design for MIMO operation. To represent the MIMO channel, it may be necessary to determine the radiation pattern of the off-focus feed antenna before the metasurface. Otherwise, the metasurface would only transmit a single data stream, and spatial multiplexing may not be utilized in this case.

The diagram included in the graph of Fig. 16a schematically illustrates the location of the feed antenna (black circle) and the metasurface (rectangular shape). The metasurface can be designed to collect a spherical wave emanating from a focus aligned with the center of the metasurface. As the feed antenna is positioned further from the focus, the beamforming gain may decrease. This may occur for two reasons: Reason 1) As the distance between the center of the metasurface and the feed antenna increases, the amplitude of the incident electromagnetic wave toward the metasurface may decrease. Reason 2) Phase compensation may no longer be effective in the non-focus region. As a result, the metasurface may not be able to form a conformal wavefront in the designated direction to achieve beamforming gain.

FIG. 16b is a diagram illustrating the gain as a function of angle of a radial non-focal feed antenna according to one embodiment of the present disclosure.

Figure 16b illustrates a different beamforming result from Figure 16a for a non-focused feed antenna. The difference between Figures 16a and 16b is that the position of the feed antenna is determined by the angular difference oriented from the center of the metasurface.

Referring to Fig. 16b, By increasing the offset angle of the radiation pattern, the radiation pattern can also exhibit a similar azimuth shifted pattern. Compared to the above-described Fig. 16a, the beam forming gain can be less diminished in the example shown in Fig. 16b. For example, in Fig. 16b, the incident angle is The radiation pattern of the offset and in Fig. 16a The radiation patterns of the offsets may exhibit different beamforming gains and patterns even though they have the same incident angle.

As described above, the distance between the metasurface and the feed antenna can be closely related to two characteristics, such as beamforming gain and radiation pattern. Since the non-focused antennas are equally spaced from the metasurface of Fig. 16b, the incident power of the feed antenna can be attenuated less in the structure of a radial non-focused antenna than in the structure of a linear non-focused feed antenna.

In one embodiment, both the structures of FIGS. 16A and 16B may have advantages. For example, in the case of FIG. 16A, since the antenna array has a linear and uniform gap, it can be printed on a flat substrate, which may facilitate the manufacturing of the structure of FIG. 16A. Furthermore, by utilizing advanced beamforming techniques such as non-uniform feed antennas or analog beamforming, the beamforming gain loss of a non-focused antenna may be mitigated compared to a focused feed antenna. Meanwhile, in the case of the structure illustrated in FIG. 16B, the refracted beam direction is well-aligned with the incident beam direction, which may make geometric modeling much easier.

Furthermore, radially arranged, non-focused antennas can achieve significant beamforming gains compared to focused antennas. Therefore, additional beamforming structures may not be required to utilize metasurface-based RF structures. This could help system designers initially utilize metasurface RF front-end structures without phase shifters.

In one embodiment, the capacity gain of the metasurface may be considered. For example, based on ITU-R M.2135, a modified MIMO spatial channel model may be simulated using the spatial channel model described in Equation 9.

For example, an urban macrocell scenario can be considered. For evaluation, a 3-sector BS (base station) antenna pattern from the 3GPP spatial channel model can be used and compared with the results of a metasurface antenna array with a typical radiation pattern. For the 3-sector scenario, the antenna pattern used for each sector can be defined as in <Mathematical Formula 10> below.

In <Mathematical Formula 10>, Is It can be, can be 20dB. 3 sectors antenna( ) can be set to 14dBi. Accordingly, the 3-sector antenna radiation pattern , can be used to extract reference channel realizations.

FIG. 17 is a diagram illustrating an antenna pattern according to one embodiment of the present disclosure. That is, FIG. 17 illustrates the overall radiation pattern of a reference antenna, a metasurface radiation pattern having a linear antenna arrangement, and a radial antenna arrangement, respectively. According to one embodiment, the metasurface radiation pattern does not include feed antenna beam steering, but can be further enhanced with an efficient analog beam steering technique using an RF phase shifter.

According to one embodiment, fast fading channel matrices can be generated by changing the radiation pattern of the metasurface and fixing all other general parameters to evaluate the system capacity.

In one embodiment, the ergodic capacity for spatial multiplexing gain of MIMO operation may be considered as a performance metric. Assuming equal power allocation across uncorrelated transmit signal vectors across transmit antennas, the instantaneous capacity may be defined as in <Mathematical Formula 11> below.

In <Mathematical Formula 11>, means determinant, Is It means unit matrix, can mean the ratio between the transmit power and the receive power (transmit SNR). The ergodic capacity can be obtained by taking the average of the instantaneous capacities for many channel realizations.

In one embodiment, the MS may be dropped 1000 times in the evaluation, with each drop lasting 0.1 seconds. The time frame of the drop may be set to 1 ms. To demonstrate the capacity improvement by spatial multiplexing, , , and can be set to . The carrier frequency reflects the 3GPP channel model. can be set to . If a different channel model is applied, the carrier frequency can be set to 100 GHz or higher. The UE can set different can be dropped to the value. To observe the capacity gain by the metasurface, the metasurface can be adopted to the BS for the same UE geometry and statistical parameters. The UE device can be configured to have an isotropic radiation pattern. The distance between neighboring elements in the BS and MS is respectively and They can be apart from each other.

FIG. 18 is a diagram illustrating an average UE (user equipment) capacity due to a meta table according to one embodiment of the present disclosure.

Referring to Figure 18, the average UE capacity can be improved due to the metasurface. This can indicate that the overall channel capacity is improved by the metasurface RF front-end design and the resulting MIMO operation. For example, In Tx and Rx antenna configuration, When the gain is set to 20 dB, the capacity of the radial antenna deployment can achieve 160.4 bps/Hz, and the capacity of the linear antenna deployment can achieve 143.2 bps/Hz. On the other hand, the capacity of the 3-sector antenna can only achieve 100.3 bps/Hz. This result can be attributed to the fact that both the radial and linear antenna deployments have higher beamforming gains than the 3-sector antenna.

In most cases, the same reason as described above may apply. That is, when the beamforming gain is high, a higher channel capacity can be obtained. For example, a radial antenna arrangement can achieve a higher capacity than a linear antenna arrangement because its radiation pattern is slightly higher than that of a linear antenna arrangement, as illustrated in FIG. 17. In other words, since the beamforming gain of a radial antenna arrangement is slightly higher than that of a linear antenna arrangement, a radial antenna arrangement can achieve a higher channel capacity than a linear antenna arrangement.

In one embodiment, a hybrid beamforming technique that enhances the radiation pattern for utilizing spatial channels may be lacking. However, as illustrated in FIG. 17, the metasurface RF front-end can achieve a single feed antenna compared to an antenna array of multiple feed antennas. Therefore, in terms of hybrid beamforming, better performance can be achieved when a metasurface structure is used.

In one embodiment, an advantage of the metasurface RF front-end structures proposed in the present disclosure is that there are no additional requirements for utilizing them in designs. In one embodiment, the gain of the metasurface may be attributed to the intrinsic properties of EM waves in that the dispersive wave can be focused on the designated direction with the unprecedented material itself.

In Fig. 18, the difference between the experimental results for the 3-sector antenna and the experimental results for the metamaterial may imply whether a metasurface can be designed and placed between the Tx and Rx to control the propagation channel.

FIG. 19 is a block diagram illustrating a configuration of an electronic device according to one embodiment of the present disclosure.

As illustrated in FIG. 19, the electronic device of the present disclosure may include a processor (1930), a transceiver (1910), and a memory (1920). However, the components of the electronic device are not limited to the examples described above. For example, the electronic device may include more or fewer components than the components described above. In addition, the processor (1930), the transceiver (1910), and the memory (1920) may be implemented in the form of a single chip.

According to one embodiment, the processor (1930) may control a series of processes that enable an electronic device to operate according to the embodiments of the present disclosure described above. For example, the processor may control components of the electronic device to transmit and receive signals in a wireless communication system according to an embodiment of the present disclosure. There may be multiple processors (1930), and the processors (1930) may perform operations for transmitting and receiving signals in the wireless communication system of the present disclosure described above by executing a program stored in the memory (1920).

According to one embodiment, when the electronic device is a terminal, the transceiver (1910) can transmit and receive signals with a base station. The signals transmitted and received with the base station can include control information and data. The transceiver (1910) can be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, an RF receiver that low-noise amplifies the received signal and down-converts the frequency, etc. However, the transceiver (1910) is only one embodiment, and the components of the transceiver (1910) are not limited to the RF transmitter and the RF receiver. In addition, the transceiver (1910) can receive a signal through a wireless channel, output it to the processor (1930), and transmit the signal output from the processor (1930) through the wireless channel.

Alternatively, according to one embodiment, when the electronic device is a base station, the transceiver (1910) can transmit and receive signals with the terminal. The signals transmitted and received with the terminal can include control information and data. The transceiver (1910) can be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, an RF receiver that low-noise amplifies the received signal and down-converts the frequency, etc. However, the transceiver (1910) is only one embodiment, and the components of the transceiver (1910) are not limited to the RF transmitter and the RF receiver. In addition, the transceiver (1910) can receive a signal through a wireless channel and output it to the processor (1930), and transmit a signal output from the processor (1930) through the wireless channel.

According to one embodiment, the memory (1920) can store programs and data necessary for the operation of the electronic device. In addition, the memory (1920) can store control information or data included in signals transmitted and received by the electronic device. The memory (1920) can be configured as a storage medium or a combination of storage media, such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. In addition, the memory (1920) can be plural. According to one embodiment, the memory (1920) can store a program for performing an operation of transmitting and receiving a signal in a wireless communication system, which are embodiments of the present disclosure described above.

FIG. 20 is a block diagram illustrating a configuration of a transceiver unit of an electronic device according to one embodiment of the present disclosure.

Referring to FIG. 20, the transceiver (1910) of FIG. 19 may include an antenna unit (2010) and a metasurface unit (2020). However, the components of the transceiver (1910) are not limited thereto, and the antenna unit (2010) or the metasurface unit (2020) may be configured separately from the transceiver (1910).

According to one embodiment, the antenna unit (2010) may include a plurality of antennas. Each of the plurality of antennas may be referred to as an antenna array or a feed antenna. Each of the plurality of antennas may include a plurality of antenna elements. According to one embodiment, the metasurface unit (2020) may include a plurality of unit cells. And, the metasurface unit (2020) may include a metasurface.

According to one embodiment, the processor (1930) of FIG. 19 may generate first beams for each of a plurality of antennas, transmit the first beams from the plurality of antennas to a metasurface unit (2020), generate second beams based on the first beams through the metasurface unit (2020), and transmit the second beams to another electronic device. At this time, the metasurface unit (2020) may be arranged to receive the first beams generated for each of the plurality of antennas. That is, the size of the metasurface included in the metasurface unit (2020) may be larger than a threshold related to receiving the first beams generated for each of the plurality of antennas. At this time, the threshold related to receiving the first beams may mean a size at which the metasurface can sufficiently receive the first beams.

In this disclosure, a novel RF front-end design utilizing metasurfaces is proposed. By employing well-designed metasurfaces and multiple antennas, the proposed design can achieve higher beamforming gain and capacity gain than current RF front-end designs without metasurfaces. There has been no research linking metasurfaces to system capacity gain. This disclosure concatenates independent metasurface studies on beamforming gain and overall system-aspect capacity gain through a novel approach to spatial channel modeling. This breaks the stereotype that metasurfaces are used for single-layer transmission.

As shown in the measured and simulated results on beamforming gain, non-focused antennas may have low beamforming gain and experience irregular radiation patterns, but can obtain significant gain from metasurfaces designed for focused antennas.

Despite the shortage of bandwidth, the limited hardware of mobile communications, high attenuation, and RF loss make higher frequencies difficult to utilize. These challenges have hindered mobile network operators from adopting higher bandwidths in cellular networks, delaying the advent of 6G. For this reason, metasurface RF front-ends can be an effective solution for overcoming the chronic limitations of current systems.

Additionally, since the size of the unit cells can correspond to the wavelength of the electromagnetic wave, as the frequency increases, more unit cells can be embedded within the same aperture of the metasurface, resulting in an increase in the link budget.

Programmable metasurfaces with adaptive phase-shifting properties can be introduced. For example, one way to achieve a programmable metasurface is to introduce varactors into the unit cell. An applied DC voltage can act as an adjustable capacitor, influencing resonance and thus controlling the effective refractive index.

The programmable metasurface, based on the RF front-end structure proposed in FIG. 5, can provide a new degree of freedom for beam steering as well as MIMO operation. This provides another efficient method for increasing device efficiency in high-frequency bands. The metasurface RF front-end design according to the present disclosure can be used for future cellular networks.

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

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

These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage device, compact disc ROM (CD-ROM), digital versatile discs (DVDs) or other forms of optical storage device, magnetic cassette. Or, they may be stored in memories composed of some or all of these combinations. In addition, each configuration memory may be included in multiple numbers.

Additionally, the program may be stored on an attachable storage device that is accessible via a communication network such as the Internet, an intranet, a local area network (LAN), a wide local area network (WLAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device implementing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device implementing an embodiment of the present disclosure.

In this disclosure, the term "computer program product" or "computer-readable medium" is used to collectively refer to media such as memory, a hard disk installed in a hard disk drive, and signals. These "computer program products" or "computer-readable mediums" are means provided for transmitting and receiving signals in a wireless communication system according to the present disclosure.

In the specific embodiments of the present disclosure described above, components included in the present disclosure are expressed singularly or plurally, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in plural may be composed of singular elements, or components expressed in singular may be composed of plural elements.

Meanwhile, the embodiments of the present disclosure disclosed in this specification and drawings are merely specific examples to easily explain the technical contents of the present disclosure and to help the understanding of the present disclosure, and are not intended to limit the scope of the present disclosure. In other words, it will be apparent to those skilled in the art that other modified examples based on the technical idea of the present disclosure are possible. In addition, the above-mentioned respective embodiments can be combined and operated with each other as needed. For example, parts of one embodiment of the present disclosure and another embodiment can be combined with each other to operate a base station and a terminal. In addition, the embodiments of the present disclosure can be applied to other communication systems, and other modified examples based on the technical idea of the embodiments can also be implemented. For example, the embodiments can be applied to an LTE system, a 5G system, a NR system, or a 6G system.

Furthermore, while the detailed description of this disclosure has described specific embodiments, it should be understood that various modifications are possible without departing from the scope of this disclosure. Therefore, the scope of this disclosure should not be limited to the described embodiments, but should be determined not only by the scope of the claims described below, but also by equivalents thereof.

Claims (16)

In an electronic device in a wireless communication system,
Transmitter and receiver; and
comprising at least one processor;
The above transceiver includes a plurality of antenna modules and a metasurface module,
The above plurality of antenna modules include a plurality of antennas,
The above multiple antenna modules receive signals from multiple layers,
At least one processor,
Generate first beams for the plurality of antennas,
Transmitting the first beams from the plurality of antennas to the metasurface module,
By the above metasurface module, second beams are generated based on the first beams,
Transmitting the second beams from the metasurface module to another electronic device,
The above second beams are formed by the plurality of layers,
The metasurface module is an electronic device arranged to receive the first beams generated for the plurality of antennas.
In the first paragraph,
The above plurality of antennas are arranged parallel to the metasurface module,
An electronic device in which the distance from the plurality of antennas to the center of the metasurface module is different.
In the first paragraph,
The above plurality of antennas are arranged in a circular shape with respect to the metasurface module,
An electronic device in which the distance from the plurality of antennas to the center of the metasurface module is the same.
In the first paragraph,
The above metasurface module comprises a plurality of unit cells,
Each of the plurality of antennas includes a plurality of antenna elements,
An electronic device wherein the spacing between the plurality of unit cells is determined based on at least one of the spacing between the plurality of antennas or the spacing between the plurality of antenna elements.
In the first paragraph,
The above metasurface module is an electronic device including a single metasurface.
In the first paragraph,
An electronic device in which the size of the metasurface module is greater than a threshold value related to an area that receives the first beams generated for the plurality of antennas.
In the first paragraph,
The above metasurface module comprises a plurality of unit cells,
Each of the plurality of antennas includes a plurality of antenna elements,
The channel between the plurality of antennas and the metasurface module is
An electronic device determined based on an angle of departure (AoD) or an angle of arrival (AoA) determined between each of the plurality of antenna elements and each of the plurality of unit cells, and a distance between each of the plurality of antenna elements and each of the plurality of unit cells.
In paragraph 7,
The radiation pattern of the plurality of antenna elements is determined based on the departure angle (AoD) or arrival angle (AoA),
An electronic device wherein a channel between the plurality of antennas and the metasurface module is determined based on the radiation patterns of the plurality of antenna elements.
In a method of operating an electronic device in a wireless communication system,
A step of generating first beams for a plurality of antennas;
A step of transmitting the first beams from the plurality of antennas to the metasurface module;
A step of generating second beams based on the first beams by the metasurface module; and
a step of transmitting the second beams from the metasurface module to another electronic device;
The above second beams are formed by a plurality of layers,
A method wherein the metasurface module is arranged to receive the first beams generated for the plurality of antennas.
In paragraph 9,
The above plurality of antennas are arranged parallel to the metasurface module,
The distance from the plurality of antennas to the center of the metasurface module is different.
In paragraph 9,
The above plurality of antennas are arranged in a circular shape with respect to the metasurface module,
The distance from the plurality of antennas to the center of the metasurface module is the same.
In paragraph 9,
The above metasurface module comprises a plurality of unit cells,
Each of the plurality of antennas includes a plurality of antenna elements,
A method in which the spacing between the plurality of unit cells is determined based on at least one of the spacing between the plurality of antennas or the spacing between the plurality of antenna elements.
In paragraph 9,
The above metasurface module is a method including a single metasurface.
In paragraph 9,
A method wherein the size of the metasurface module is greater than a threshold value related to an area that receives the first beams generated for the plurality of antennas.
In paragraph 9,
The above metasurface module comprises a plurality of unit cells,
Each of the plurality of antennas includes a plurality of antenna elements,
The channel between the plurality of antennas and the metasurface module is
A method determined based on an angle of departure (AoD) or an angle of arrival (AoA) determined between each of the plurality of antenna elements and each of the plurality of unit cells, and a distance between each of the plurality of antenna elements and each of the plurality of unit cells.
In Article 15,
The radiation pattern of the plurality of antenna elements is determined based on the departure angle (AoD) or arrival angle (AoA),
A method in which a channel between the plurality of antennas and the metasurface module is determined based on the radiation patterns of the plurality of antenna elements.