Intelligent metasurface cascade channel estimation method, system and intelligent metasurface

Abstract

This invention provides a method, system, and intelligent metasurface cascaded channel estimation for smart metasurfaces. The method includes the following steps: receiving pilot signals from a user equipment; uplinking the pilot signals to a base station based on a preset target codebook, where the target codebook is an orthogonal array response set, and the orthogonal array response parameters within the set include several angle pairs composed of azimuth and elevation angles within the intelligent metasurface subspace; receiving a precoding matrix fed back from the base station and extracting target angle pairs by combining it with the target codebook, where the target angle pairs are uplink / downlink channels; and downlinking base station data from the base station to the user equipment based on the downlink channels. This invention can compress the codebook of the intelligent metasurface to reduce dimensionality; simultaneously, since codebook elements are angle-dependent, it employs a unified uplink and downlink channel estimation and transmission mechanism, utilizing the reciprocity of angles to use uplink channel angle information for downlink signal transmission, thereby eliminating the need for additional pilot signals.

Description

Technical Field

[0001] This invention belongs to the technical field of data transmission, and in particular relates to a smart metasurface cascaded channel estimation method, system, and smart metasurface. Background Technology

[0002] Channel estimation is a critical issue in wireless communication systems, especially in complex environments. As an emerging technology, RIS (Reconfigurable Intelligence Surface) also faces some unique challenges in the application of channel estimation, such as the drawback of high overhead.

[0003] The high overhead of channel estimation using smart metasurfaces stems primarily from two aspects:

[0004] Firstly, RIS-assisted wireless communication requires the estimation of a large number of parameters, and RIS is usually equipped with a large number of electromagnetic units, resulting in a huge dimension of the cascaded channel matrix, which generally requires the transmission of pilot signals with a channel dimension equivalent to that of the channel.

[0005] Secondly, in FDD (Frequency Division Duplexing) systems, the reciprocity of uplink and downlink transmission channels fails, requiring separate uplink and downlink estimations, which further increases pilot overhead. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a smart metasurface cascaded channel estimation method, system and smart metasurface, to solve the problems of large pilot signal dimension and many pilots when performing channel estimation based on smart metasurface in the prior art.

[0007] In a first aspect, the present invention provides a smart metasurface cascaded channel estimation method, the method comprising the following steps:

[0008] Receive pilot signals from user equipment;

[0009] The pilot signal is transmitted uplink to the base station based on a preset target codebook, wherein the target codebook is an orthogonal array response set, and the orthogonal array response parameters in the set include several angle pairs composed of azimuth and elevation angles in the intelligent metasurface subspace;

[0010] The target angle pair is obtained by combining the precoding matrix fed back by the base station with the target codebook, wherein the target angle pair is the uplink / downlink channel;

[0011] The base station data sent by the base station is transmitted downlink to the user equipment based on the downlink channel.

[0012] In one possible implementation of this application, the step of generating the target codebook specifically includes:

[0013] Initialize collection With sets It is an empty set;

[0014] The set of elevation angles Θ based on the spatial dimension of intelligent metasurface computation;

[0015] Set θ i ∈Θ, calculate the set of azimuth angles Φ(θ) in spatial dimensions. i );

[0016] Based on the elevation angle set Θ and the azimuth angle set Φ, collect orthogonal angle pairs. Update collection

[0017] Based on the updated set Collect orthogonal angle pairs in the channel subspace of intelligent metasurfaces To update the set Where i is the angle number.

[0018] In one possible implementation of this application, the target codebook is an orthogonal array response set of the subspace dimension of a smart metasurface, wherein the subspace dimension

[0019] In one possible implementation of this application, calculating the set of elevation angles Θ in the spatial dimension specifically includes:

[0020] The elevation angle set Θ is calculated based on a preset elevation angle calculation expression, which is as follows:

[0021]

[0022] Among them, M V For the electromagnetic units arranged in the z-direction of the smart metasurface, d V Let be the spacing of the smart metasurface in the z-direction, and k be the number of the electromagnetic unit arranged in the z-direction of the smart metasurface.

[0023] In one possible implementation of this application, the set of azimuth angles Φ(θ) in the spatial dimension is calculated. i Specifically, this includes:

[0024] The set of elevation angles Φ(θ) is calculated based on a preset azimuth angle calculation expression. i The azimuth calculation expression is as follows:

[0025]

[0026] Among them, M HFor the electromagnetic units configured in the y-direction of the smart metasurface, d H Let θ be the spacing of the smart metasurfaces in the y-direction, l be the index of the electromagnetic units arranged in the z-direction of the smart metasurfaces, and θ be the position of the array. i Angle of elevation, is the azimuth angle, and i is the angle index.

[0027] In one possible implementation of this application, orthogonal angle pairs are collected based on the elevation angle set Θ and the azimuth angle set Φ. Update collection Specifically include:

[0028] Extract all azimuth and elevation angles to obtain angle pairs

[0029] The initialized collection The elements of the corner pairs are merged to obtain the updated set. Where η is the subspace dimension of the smart metasurface.

[0030] In one possible implementation of this application, based on the updated set Collect orthogonal angle pairs in the channel subspace of intelligent metasurfaces To update the set Specifically include:

[0031] Based on the angle pair expression combined with the set Collect all orthogonal array response vectors

[0032] The initialized collection The elements of the orthogonal array response vectors are merged to obtain the updated set. Where i is the angle index and η is the subspace dimension of the smart metasurface.

[0033] In a second aspect, the present invention provides a smart metasurface, including a processor, wherein the processor, when executed, implements any of the smart metasurface cascaded channel estimation methods described in the present invention.

[0034] In one possible implementation of this application, the smart metasurface further includes a reflective surface electrically connected to the processor, wherein the reflective surface of the smart metasurface is a uniform rectangular array, with M arranged in the y-direction. H There are 10 electromagnetic units, and the spacing between these units in the y-direction is d. H M is configured in the z direction V There are 10 electromagnetic units, and the spacing between these units in the z-direction is d. V A total of M = M are configured in the yz plane. H ×M V One electromagnetic unit.

[0035] Thirdly, the present invention provides an intelligent metasurface cascaded channel estimation system, the system comprising:

[0036] User equipment is used to transmit pilot signals and receive base station data;

[0037] The smart metasurface described above is used to determine several angle pairs composed of azimuth and elevation angles within the smart metasurface subspace, and to use these angle pairs to transmit the pilot signal uplink to the base station, as well as to receive the precoding matrix fed back by the base station to determine the target angle pair, and to transmit the base station data sent by the base station downlink to the user equipment based on the downlink channel, wherein the target angle pair is the uplink / downlink channel;

[0038] A base station is used to receive different beam signals transmitted from several corner pairs and evaluate the corresponding signal quality to determine the optimal beam direction, and to feed back a precoding matrix based on the optimal beam direction, and to transmit the base station data.

[0039] As described above, the intelligent metasurface cascaded channel estimation method, system, and intelligent metasurface of the present invention have the following beneficial effects: they can compress the codebook of the intelligent metasurface to reduce dimensionality; at the same time, the codebook elements are angle-dependent, and an uplink and downlink unified channel estimation and transmission mechanism is adopted. By utilizing the reciprocity of angles, the uplink channel angle information is used for downlink signal transmission, thereby eliminating the need for additional pilot signals. Attached Figure Description

[0040] Figure 1 The diagram shown is an architecture diagram of the intelligent metasurface cascaded channel estimation system of the present invention in one embodiment;

[0041] Figure 2 The diagram shows the steps of the intelligent metasurface cascaded channel estimation method of the present invention in one embodiment;

[0042] Component designation explanation

[0043] Steps S202~S208 Detailed Implementation

[0044] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0045] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0046] The following embodiments of the present invention provide a smart metasurface cascaded channel estimation method, system, and smart metasurface for channel estimation in wireless communication. The smart metasurface, or RIS (Reconfigurable Intelligence Surface), is an emerging technology capable of defining new wireless transmission and propagation modes and controlling communication channels (reshaping the wireless channel). Specifically, it is a metasurface containing electronically controllable and low-power analog processing elements that can adjust the absorption, reflection, refraction, and phase of passive reflective elements in real time, thereby guiding incident electromagnetic signals to the desired direction and maximizing the effective channel gain by adjusting the phase and amplitude of reflected signals. RIS offers numerous advantages, such as being deployable in various locations and attaching to surfaces like buildings, vehicles, and interior walls with minimal cost and effort. It is also compatible with current radio technologies and supports advanced wireless waveforms and full-duplex and half-duplex communication across a wide bandwidth and frequency range.

[0047] Currently, the key issue in channel estimation for passive RIS lies in the joint design of pilot sequences, RIS codebooks (i.e., RIS reflection coefficients adjusted in real time during pilot training), and receiver signal processing algorithms. The main focus of this invention is how to accurately estimate the RIS cascaded channel with minimal pilot overhead. Specifically, this invention proposes a spatial orthogonal basis expansion model in the actual physical angle domain, utilizing the inherent spatial correlation of the RIS channel to obtain an effective RIS configuration codebook. While the dimension of the traditional Discrete Fourier Transform (DFT) codebook is comparable to the number of RIS units, the codebook dimension described in this invention is determined by the rank of the cascaded channel matrix. This means the proposed codebook can shorten the subspace that needs to be scanned during RIS codebook configuration, achieving dimensionality reduction. Furthermore, this invention employs a unified uplink and downlink channel estimation and transmission mechanism. The transmission mechanism starts from the angle domain, utilizing the reciprocity of angles to use uplink channel angle information for downlink signal transmission, thus eliminating the need for additional pilots.

[0048] Specifically, please refer to Figure 1 In one embodiment of the invention, the intelligent metasurface cascaded channel estimation system of the present invention includes:

[0049] User equipment is used to transmit pilot signals and receive base station data;

[0050] As described above, the intelligent metasurface is used to determine several angle pairs composed of azimuth and elevation angles within the intelligent metasurface subspace, and to use these angle pairs to transmit the pilot signal uplink to the base station, as well as to receive the precoding matrix fed back by the base station to determine the target angle pair, and to transmit the base station data sent by the base station downlink to the user equipment based on the downlink channel, wherein the target angle pair is the uplink / downlink channel;

[0051] A base station is used to receive different beam signals transmitted from several corner pairs and evaluate the corresponding signal quality to determine the optimal beam direction, and to feed back a precoding matrix based on the optimal beam direction, and to transmit the base station data.

[0052] It should be noted that, in this embodiment, the system architecture diagram is as follows: Figure 1 As shown, the intelligent metasurface cascaded channel estimation system of the present invention includes user equipment (UE), an intelligent metasurface (RIS), and a base station (BS). The base station is configured with N uniform linear array antennas. The intelligent metasurface includes a processor and a reflective surface, wherein the reflective surface of the intelligent metasurface is a uniform rectangular array with M antennas arranged in the y-direction. H There are 10 electromagnetic units, and the spacing between these units in the y-direction is d. H M is configured in the z direction V There are 10 electromagnetic units, and the spacing between these units in the z-direction is d. V A total of M = M are configured in the yz plane. H ×M V In application, the user equipment (UE) emits pilot signals, and the intelligent metasurface timing-scanning beam assists the UE-RIS-BS in uplink transmission. During transmission, the specific target codebook is used, i.e., different orthogonal angle pairs are used for uplink transmission. Then, the base station evaluates the quality of the received pilot signals and calculates the optimal beam direction feedback precoding matrix for the intelligent metasurface to determine the target angle pairs. Utilizing the reciprocity of angles, the uplink channel angle information is used for downlink signal transmission. After obtaining the corresponding downlink channel, the intelligent metasurface assists the BS-RIS-UE in downlink transmission.

[0053] Furthermore, considering the passive operation of the RIS, the RIS cannot directly transmit or receive pilot signals; they must be transmitted either by the base station or the user. Therefore, it is necessary to directly estimate the RIS-assisted cascaded (two-segment) channel. The UE transmits pilot signals to the BS, and the RIS adjusts its reflection coefficients in real time according to a pre-designed reflection pattern (e.g., codebook) to assist in cascaded channel estimation. However, the complexity and resource requirements of channel estimation increase with the number of RIS electromagnetic units. During channel estimation, the RIS needs to try more beam direction combinations to find the optimal beam direction, which leads to increased training time. The more combinations, the longer the training time. Therefore, the codebook size needs to be reduced. Thus, methods such as codebook dimensionality and utilizing channel reciprocity can be considered to reduce the codebook scanning time and signaling overhead of channel estimation.

[0054] In one embodiment of the invention, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings of the embodiment, taking the smart metasurface as the implementing subject.

[0055] Specifically, please refer to Figure 2 In one embodiment of the invention, the intelligent metasurface cascaded channel estimation method of the present invention includes the following steps:

[0056] Step S202: Receive pilot signals sent by user equipment;

[0057] Step S204: The pilot signal is transmitted uplink to the base station based on a preset target codebook, wherein the target codebook is an orthogonal array response set, and the orthogonal array response parameters in the set include several angle pairs composed of azimuth and elevation angles in the smart metasurface subspace;

[0058] Step S206: Receive the precoding matrix fed back by the base station and extract the target corner pair by combining it with the target codebook, wherein the target corner pair is the uplink / downlink channel;

[0059] Step S208: The base station data sent by the base station is transmitted downlink to the user equipment based on the downlink channel.

[0060] It should be noted that in this embodiment, during data transmission, the direct link between the BS and the UE is interrupted due to obstruction by obstacles, making it impossible to carry out data transmission services. Therefore, the RIS is deployed within the line-of-sight range of the BS and the UE. By modulating and reflecting the signals transmitted by the BS, the BS is able to resume providing data transmission services to the UE. The UE is randomly distributed in the coverage area of ​​the BS, and the BS does not know the channels related to the UE. Therefore, when the UE wants to access the BS, channel estimation needs to be performed before data transmission. This embodiment will further explain how to perform channel estimation based on the smart metasurface.

[0061] Specifically, the user repeatedly sends several pilot signals to the base station within a preset time range. The intelligent metasurface periodically scans different beam directions based on a preset target codebook to assist the base station in receiving the beam signals reflected by the intelligent metasurface. That is, it first receives the pilot signals sent by the user equipment, and then uses several corner pairs in the target codebook to reflect and transmit the pilot signals uplink to the base station. The number of pilot signals is the same as the number of corner pairs. Then, the base station determines the optimal beam direction based on the quality of the received uplink pilot signals and feeds back a precoding matrix to the intelligent metasurface. This matrix includes the optimal corner pairs. Therefore, after receiving the precoding matrix fed back by the base station, the intelligent metasurface can extract the target corner pairs by combining them with the target codebook. Correspondingly, the target corner pairs are the uplink / downlink channels. Thus, during downlink transmission, the base station data sent by the base station can be transmitted downlink to the user equipment based on the downlink channels.

[0062] Furthermore, in one embodiment of the invention, the step of generating the target codebook specifically includes:

[0063] Initialize collection With sets It is an empty set;

[0064] The set of elevation angles Θ based on the spatial dimension of intelligent metasurface computation;

[0065] Set θ i ∈Θ, calculate the set of azimuth angles Φ(θ) in spatial dimensions. i );

[0066] Based on the elevation angle set Θ and the azimuth angle set Φ, collect orthogonal angle pairs. Update collection

[0067] Based on the updated set Collect orthogonal angle pairs in the channel subspace of intelligent metasurfaces To update the set Where i is the angle number.

[0068] It should be noted that, in this embodiment, the channel coefficients of adjacent RIS units are similar, determined by the number of clusters (assumed to be independent sub-paths with the same delay) and their angular distribution in the propagation environment. For a RIS with a typical planar structure and subwavelength units, there will be a large amount of spatial correlation under isotropic scattering. The spatial correlation can be interpreted as follows: any M-dimensional RIS channel h belongs to a subspace with a dimension much smaller than M (composed of eigenvalues ​​and their corresponding eigenvectors, the subspace dimension is approximately equal to the number of eigenvalues). To minimize the search space during pilot transmission, a set of azimuth-elevation pairs must first be found. These pairs will constitute the orthogonal basis of the RIS channel. Specifically, assuming aRIS (π / 2, 0) is a component of the angle pair, with a RIS Using (π / 2,0) as the reference point, search for all vectors that can produce mutually orthogonal array responses.

[0069] Firstly, according to Expressions can and The obtained array response inner product is written as:

[0070]

[0071] Among them, M V For the electromagnetic units arranged in the z-direction of the smart metasurface, d V Let M be the spacing of the electromagnetic units in the z-direction, k be the index of the electromagnetic units arranged in the z-direction on the smart metasurface, and M be the position of the electromagnetic units. H For the electromagnetic units configured in the y-direction of the smart metasurface, d H Let represent the spacing of the electromagnetic units in the y-direction, and l represent the index of the electromagnetic units arranged on the smart metasurface in the z-direction.

[0072]

[0073] therefore, And T(Ψ) rewritten as:

[0074]

[0075] Among them, collecting the corner pairs that can produce mutually orthogonal array responses is to obtain Therefore, separate searches are required. The set of elevation angles and the set of azimuth angles T(Ψ)=0.

[0076] Furthermore, in one embodiment of the invention, calculating the set of elevation angles Θ of the spatial dimension specifically includes:

[0077] The elevation angle set Θ is calculated based on a preset elevation angle calculation expression, which is as follows:

[0078]

[0079] Among them, M V For the electromagnetic units arranged in the z-direction of the smart metasurface, d V Let be the spacing of the smart metasurface in the z-direction, and k be the number of the electromagnetic unit arranged in the z-direction of the smart metasurface.

[0080] It should be noted that, in this embodiment, the specific calculation... The set of elevation angles at time, where, Where k = ±1,…,±(M) V -1), that is It can be viewed as a periodic function with a period of . Since assuming (π / 2, 0) is a component of the angle pair, that is, taking θ1 = 0 as the reference point, finding other elevation angles within the period can satisfy... Right now By solving We can obtain a set of mutually orthogonal elevation angles, and further obtain... Where k = ±1,…,±(M) V -1), where the set of elevation angles Θ={θ1,…,θ n}, where M V For the electromagnetic units arranged in the z-direction of the smart metasurface, d V Let be the spacing of the smart metasurface in the z-direction, and k be the number of the electromagnetic unit arranged in the z-direction of the smart metasurface.

[0081] Furthermore, in one embodiment of the invention, the set of azimuth angles Φ(θ) of the spatial dimension is calculated. i Specifically, this includes:

[0082] The set of elevation angles Φ(θ) is calculated based on a preset azimuth angle calculation expression. i The azimuth calculation expression is as follows:

[0083]

[0084] Among them, M H For the electromagnetic units configured in the y-direction of the smart metasurface, d H Let θ be the spacing of the smart metasurfaces in the y-direction, l be the index of the electromagnetic units arranged in the z-direction of the smart metasurfaces, and θ be the position of the array. i Angle of elevation, is the azimuth angle, and i is the angle index.

[0085] It should be noted that, in this embodiment, the azimuth set when T(Ψ) = 0 is specifically calculated, where, Where l = ±1,…,±(M) H -1), that is, T(Ψ) can be regarded as a periodic function with a period of . Due to assumption a RIS (π / 2, 0) is a component of the angle pair, that is, with Using a reference point, we search for other azimuth angles within the period that satisfy T(Ψ) = 0, i.e. To further collect data with elevation angle θ i All azimuth angles corresponding to the relevant orthogonal beams, where the azimuth angle set is... Among them, M HFor the electromagnetic units configured in the y-direction of the smart metasurface, d H Let θ be the spacing of the smart metasurfaces in the y-direction, l be the index of the electromagnetic units arranged in the z-direction of the smart metasurfaces, and θ be the position of the array. i Angle of elevation, is the azimuth angle, and i is the angle index.

[0086] Furthermore, in one embodiment of the invention, orthogonal angle pairs are collected based on the elevation angle set Θ and the azimuth angle set Φ. Update collection Specifically include:

[0087] Extract all azimuth and elevation angles to obtain angle pairs

[0088] The initialized collection The elements of the corner pairs are merged to obtain the updated set. Where η is the subspace dimension of the smart metasurface.

[0089] Furthermore, in one embodiment of the invention, based on the updated set Collect orthogonal angle pairs in the channel subspace of intelligent metasurfaces To update the set Specifically include:

[0090] Based on the angle pair expression combined with the set Collect all orthogonal array response vectors

[0091] The initialized collection The elements of the orthogonal array response vectors are merged to obtain the updated set. Where i is the angle index and η is the subspace dimension of the smart metasurface.

[0092] It should be noted that, in this embodiment, the set is initialized beforehand. With sets Since the set is empty, after gradually obtaining the set of elevation angles Θ and the set of azimuth angles Φ, it needs to be updated. This is done by merging elements. Specifically, the set of elevation angles Θ = {θ1,…,θ...} n}, azimuth set n represents the total number of angles. Since the dimension of the subspace of the intelligent metasurface decreases, specifically to η, the angle pairs obtained by extracting all azimuth and elevation angles are... Then initialize the set The elements of the corner pairs are merged to obtain the updated set. Furthermore, based on the angle pair expression combined with the set Collect all orthogonal array response vectors in, This is a diagonal pair expression; the specific calculation process is known to those skilled in the art and will not be elaborated here. Then, the initialized set... The elements of the orthogonal array response vectors are merged to obtain the updated set. Where i is the angle index, η is the subspace dimension of the intelligent metasurface, and the target codebook is finally obtained, specifically the orthogonal array response set of the subspace dimension of the intelligent metasurface, where the subspace dimension...

[0093] This application also provides a smart metasurface, which includes a processor and a reflective surface. The reflective surface is electrically connected to the processor. When the processor executes, it implements any of the smart metasurface cascaded channel estimation methods described above. The reflective surface of the smart metasurface is a uniform rectangular array, with M-shaped elements arranged in the y-direction. H There are 10 electromagnetic units, and the spacing between these units in the y-direction is d. H M is configured in the z direction V There are 10 electromagnetic units, and the spacing between these units in the z-direction is d. V A total of M = M are configured in the yz plane. H ×M V One electromagnetic unit.

[0094] It should be noted that, in this embodiment, as Figure 1 As shown, the composition of the intelligent metasurface (RIS) includes a processor and a reflective surface, which can be connected by cables or optical fibers. The reflective surface of the RIS consists of a large number of reflective units (usually electrical components made of electromagnetic materials). These units can adjust the characteristics of the reflected wave, including phase and amplitude, according to control signals. The operating state of each reflective unit (e.g., phase adjustment) directly affects the signal propagation path and signal strength, thereby enhancing, directing, or suppressing the wireless signal. Each reflective unit can independently adjust the phase or amplitude of the reflected signal, while the processor is responsible for controlling the operation of all reflective units to achieve the desired signal modulation effect. This is achieved by communicating with each reflective unit to dynamically adjust its state, including signal control, specifically adjusting the phase, amplitude, and other parameters of the reflective unit according to actual requirements (e.g., feedback from the base station, user location, or environmental conditions); information processing, processing feedback information from the base station, user equipment, or other network elements, and optimizing the reflective surface configuration based on this information; and coordination functions, specifically coordinating the operation of multiple reflective units to ensure optimal signal propagation.

[0095] Furthermore, since the specific implementation of the processor's execution process in this embodiment corresponds to the aforementioned method embodiment, the same details will not be repeated here.

[0096] Preferably, the processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0097] In the embodiments provided by this invention, it should be understood that the disclosed systems or methods can be implemented in other ways. For example, the system embodiments described above are merely illustrative. For instance, the division of modules / units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or units may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interfaces, devices, or modules or units, and may be electrical, mechanical, or other forms.

[0098] The modules / units described as separate components may or may not be physically separate. The components shown as modules / units may or may not be physical modules; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules / units can be selected to achieve the objectives of the embodiments of the present invention, depending on actual needs. For example, the functional modules / units in the various embodiments of the present invention may be integrated into one processing module, or each module / unit may exist physically separately, or two or more modules / units may be integrated into one module / unit.

[0099] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0100] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for estimating the channel of a smart metasurface cascade, characterized in that, include: Receive pilot signals from user equipment; The pilot signal is transmitted uplink to the base station based on a preset target codebook, wherein the target codebook is an orthogonal array response set, and the orthogonal array response parameters in the set include several angle pairs composed of azimuth and elevation angles in the intelligent metasurface subspace; The target angle pair is obtained by combining the precoding matrix fed back by the base station with the target codebook, wherein the target angle pair is the uplink / downlink channel; The base station data sent by the base station is transmitted downlink to the user equipment based on the downlink channel; The specific steps for generating the target codebook include: initializing the set. With sets An empty set; the set of elevation angles Θ based on the spatial dimension of the intelligent metasurface computation; setting θ i ∈Θ, calculate the set of azimuth angles Φ(θ) in spatial dimensions. i Based on the elevation angle set Θ and the azimuth angle set Φ, collect orthogonal angle pairs. Update collection Based on the updated set Collect orthogonal angle pairs in the channel subspace of intelligent metasurfaces To update the set Where i is the angle index; The calculation of the set of elevation angles Θ in spatial dimensions specifically includes: calculating the set of elevation angles Θ based on a preset elevation angle calculation expression, as follows: Where k = ±1,…,±(M) V -1)}; Among them, M V For the electromagnetic units arranged in the z-direction of the smart metasurface, d V Let be the spacing of the smart metasurfaces in the z-direction, and k be the number of the electromagnetic units of the smart metasurfaces in the z-direction. Calculate the set of azimuth angles Φ(θ) in spatial dimensions i Specifically, this includes: The set of elevation angles Φ(θ) is calculated based on a preset azimuth angle calculation expression. i The azimuth calculation expression is as follows: Among them, M H For the electromagnetic units configured in the y-direction of the smart metasurface, d H Let θ be the spacing of the smart metasurfaces in the y-direction, l be the index of the electromagnetic units arranged in the z-direction of the smart metasurfaces, and θ be the position of the array. i Angle of elevation, is the azimuth angle, and i is the angle index; Based on the elevation angle set Θ and the azimuth angle set Φ, collect orthogonal angle pairs. Update collection Specifically include: Extract all azimuth and elevation angles to obtain angle pairs The initialized collection The elements of the corner pairs are merged to obtain the updated set. Where η is the subspace dimension of the smart metasurface; Based on the updated set Collect orthogonal angle pairs in the channel subspace of intelligent metasurfaces To update the set Specifically include: Based on the angle pair expression combined with the set Collect all orthogonal array response vectors The initialized collection The elements of the orthogonal array response vectors are merged to obtain the updated set. Where i is the angle index and η is the subspace dimension of the smart metasurface.

2. The intelligent metasurface cascaded channel estimation method according to claim 1, characterized in that, The target codebook is an orthogonal array response set of the subspace dimension of the intelligent metasurface, where the subspace dimension...

3. A smart metasurface, characterized in that, Includes a processor, which, when executed, implements the intelligent metasurface cascaded channel estimation method according to any one of claims 1 to 2.

4. The intelligent metasurface according to claim 3, characterized in that, The intelligent metasurface also includes a reflective surface electrically connected to the processor, wherein the reflective surface of the intelligent metasurface is a uniform rectangular array, with M arranged in the y-direction. H There are 10 electromagnetic units, and the spacing between these units in the y-direction is d. H M is configured in the z direction V There are 10 electromagnetic units, and the spacing between these units in the z-direction is d. V A total of M = M are configured in the yz plane. H ×M V One electromagnetic unit.

5. A smart metasurface cascaded channel estimation system, characterized in that, include: User equipment is used to transmit pilot signals and receive base station data; The smart metasurface as described in claim 3 is used to determine several angle pairs composed of azimuth and elevation angles within the smart metasurface subspace, and to use these angle pairs to uplink the pilot signal to the base station, and to receive the precoding matrix fed back by the base station to determine the target angle pair, and to downlink the base station data sent by the base station to the user equipment based on the downlink channel, wherein... The target angle pair is the uplink / downlink channel; A base station is used to receive different beam signals transmitted from several corner pairs and evaluate the corresponding signal quality to determine the optimal beam direction, and to feed back a precoding matrix based on the optimal beam direction, and to transmit the base station data.

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