Intelligent metasurface cascade channel estimation method and system and intelligent metasurface

Abstract

The invention provides an intelligent metasurface cascade channel estimation method, an intelligent metasurface cascade channel estimation system and an intelligent metasurface. The method comprises the following steps: receiving a pilot signal sent by user equipment; the pilot signal is uplink transmitted to a base station based on a preset target codebook, the target codebook is an orthogonal array response set, and orthogonal array response parameters in the set comprise a plurality of angle pairs formed by azimuth angles and elevation angles in an intelligent metasurface subspace; receiving a pre-coding matrix fed back by the base station, and combining the pre-coding matrix with a target codebook to extract a target angle pair, wherein the target angle pair is an uplink / downlink channel; and transmitting the base station data sent by the base station to the user equipment in a downlink manner based on a downlink channel. According to the invention, the codebook of the intelligent metasurface can be compressed to reduce the dimensionality; meanwhile, codebook elements are related to angles, a unified uplink and downlink channel estimation and transmission mechanism is adopted, and uplink channel angle information is used for downlink signal transmission by utilizing the reciprocity of the angles, so that the pilot frequency does not need to be increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of data transmission, and in particular relates to an intelligent metasurface cascade channel estimation method, system and intelligent metasurface. Background Art

[0002] Channel estimation is a key 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 disadvantage of high overhead.

[0003] Among them, the high overhead disadvantage of using smart metasurfaces for channel estimation mainly comes from two aspects:

[0004] One is that RIS-assisted wireless communications require a large number of parameters to be estimated, and RIS is usually equipped with a large number of electromagnetic units, resulting in a large dimension of the cascaded channel matrix, which generally requires sending pilot signals equivalent to the channel dimension;

[0005] The second is that the reciprocity of uplink and downlink transmission channels in the FDD (Frequency Division Duplexing) system fails, and uplink and downlink estimation need to be performed separately, further increasing the pilot overhead. Summary of the invention

[0006] In view of the shortcomings of the prior art described above, the object of the present invention is to provide an intelligent metasurface cascade channel estimation method, system and intelligent metasurface, which are used to solve the problems of large pilot signal dimension and increased number of pilots when performing channel estimation based on intelligent metasurface in the prior art.

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

[0008] receiving a pilot signal sent by a user equipment;

[0009] Uplink transmitting the pilot signal to a 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 a plurality of angle pairs consisting of azimuth angles and elevation angles in a smart metasurface subspace;

[0010] Receive the precoding matrix fed back by the base station and extract it in combination with the target codebook to obtain a target angle pair, wherein the target angle pair is an uplink / downlink channel;

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

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

[0013] Initializing a Collection With Collection is an empty set;

[0014] The elevation angle set Θ of the spatial dimension is calculated based on the intelligent metasurface;

[0015] Setting θ i ∈Θ, calculate the azimuth set Φ(θ i );

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

[0017] Based on the updated collection Collect orthogonal angle pairs in the channel subspace of the smart metasurface To update the collection Among them, i is the angle number.

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

[0019] In a possible implementation of the present application, calculating the elevation angle set θ of the spatial dimension specifically includes:

[0020] The elevation angle set Θ is calculated based on the preset elevation angle calculation expression. The elevation angle calculation expression is as follows:

[0021]

[0022] Among them, M V is the electromagnetic unit configured on the smart metasurface in the z direction, d V is the configuration interval of the smart metasurface in the z direction, and k is the serial number of the electromagnetic units configured on the smart metasurface in the z direction.

[0023] In a possible implementation of the present application, the azimuth angle set Φ(θ i ), including:

[0024] Calculate the elevation angle set Φ(θ based on the preset azimuth calculation expression i ), the azimuth angle calculation expression is as follows:

[0025]

[0026] Among them, M His the electromagnetic unit configured on the smart metasurface in the y direction, d H is the configuration interval of the smart metasurface in the y direction, l is the serial number of the electromagnetic units configured in the smart metasurface in the z direction, θ i is the elevation angle, is the azimuth, and i is the angle number.

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

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

[0029] The collection to be initialized Merge the elements with the corner pair to obtain an updated set Where η is the subspace dimension of the smart metasurface.

[0030] In a possible implementation of the present application, based on the updated set Collect orthogonal angle pairs in the channel subspace of the smart metasurface To update the collection Specifically include:

[0031] Combine the sets based on the angle pair expression Collect all orthogonal array response vectors

[0032] The collection to be initialized Merge the elements with the orthogonal array response vector to obtain an updated set Among them, i is the angle number and η is the subspace dimension of the smart hypersurface.

[0033] In a second aspect, the present invention provides an intelligent metasurface, comprising a processor, which, when executed, implements any one of the intelligent metasurface cascade channel estimation methods.

[0034] In a possible implementation of the present 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, and M is configured in the y direction. H The electromagnetic units are arranged at intervals of d in the y direction. H , M is configured in the z direction V The electromagnetic units are arranged at intervals of d in the z direction. V , in the yz plane, M=M H ×M V An electromagnetic unit.

[0035] In a third aspect, the present invention provides an intelligent metasurface cascade channel estimation system, the system comprising:

[0036] User equipment, used to send out pilot signals and receive base station data;

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

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

[0039] As described above, the intelligent metasurface cascade channel estimation method, system and intelligent metasurface described in the present invention have the following beneficial effects: the codebook of the intelligent metasurface can be compressed to reduce the dimension; at the same time, the codebook elements are related to the angle, and a unified uplink and downlink channel estimation and transmission mechanism is adopted, and the reciprocity of angles is utilized to use the uplink channel angle information for downlink signal transmission, thereby eliminating the need for more pilot signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Shown is a structural diagram of an intelligent metasurface cascade channel estimation system in one embodiment of the present invention;

[0041] Figure 2 It is a diagram showing the steps of the intelligent metasurface cascade channel estimation method in one embodiment of the present invention;

[0042] Component number description

[0043] Steps S202 to S208 DETAILED DESCRIPTION

[0044] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0045] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0046] The following embodiments of the present invention provide an intelligent metasurface cascade channel estimation method, system and intelligent metasurface for channel estimation in wireless communications, wherein the intelligent metasurface, referred to as RIS (Reconfigurable Intelligence Surface) in English, is an emerging technology that can define new wireless transmission and propagation modes and control communication channels (reshape wireless channels). Specifically, it is a metasurface that includes electronically controllable and low-power analog processing elements, which can adjust the absorption, reflection, refraction and phase of passive reflective elements in real time, thereby guiding the incident electromagnetic signal to the desired direction, and reflecting the phase and amplitude of the signal to maximize the effective channel gain. RIS has many advantages, such as being deployable in different locations and attached to surfaces such as buildings, vehicles and indoor walls with minimal cost and effort, and being compatible with current radio technology and supporting advanced wireless waveforms and full-duplex and half-duplex communications over a wide bandwidth and frequency range.

[0047] At present, for the channel estimation of passive RIS, the key problem is to jointly design the pilot sequence, RIS codebook (i.e., the RIS reflection coefficient adjusted in real time during pilot training) and the receiving end signal processing algorithm. How to accurately estimate the RIS cascade channel with the least pilot overhead is the main focus of the present invention. Among them, the present invention proposes a spatial orthogonal basis expansion model in the actual physical angle domain, and uses the inherent spatial correlation of the RIS channel to obtain an effective RIS configuration codebook. The dimension of the traditional discrete Fourier transform (DFT) codebook is equivalent to the number of RIS units. The codebook dimension described in the present invention is determined by the rank of the cascade channel matrix, that is, the proposed codebook can shorten the subspace that needs to be scanned when the RIS codebook is configured, thereby achieving the purpose of dimensionality reduction. In addition, the present invention adopts a unified uplink and downlink channel estimation and transmission mechanism. The transmission mechanism starts from the angle domain and uses the reciprocity of the angle to use the uplink channel angle information for downlink signal transmission, so there is no need to increase the number of pilots.

[0048] Specifically, see Figure 1 In one embodiment of the invention, the intelligent metasurface cascade channel estimation system of the present invention comprises:

[0049] User equipment, used to send out pilot signals and receive base station data;

[0050] The smart metasurface as described above is used to determine a number of angle pairs consisting of azimuth and elevation angles in a subspace of the smart metasurface, and use the several angle pairs to uplink the pilot signal to a base station, and receive a precoding matrix fed back by the base station to determine a target angle pair, and downlink the base station data sent by the base station to the user equipment based on a downlink channel, wherein the target angle pair is an uplink / downlink channel;

[0051] A base station is used to receive different beam signals transmitted from several angle pairs and evaluate the corresponding signal quality to determine the best beam direction, and to feed back a precoding matrix based on the best beam direction, and to send out 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 cascade channel estimation system of the present invention includes a user equipment (UE, User Equipment), an intelligent metasurface (RIS, Reconfigurable Intelligent Surface) and a base station (BS, Base Station), wherein 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, and M H The electromagnetic units are arranged at intervals of d in the y direction. H , M is configured in the z direction V The electromagnetic units are arranged at intervals of d in the z direction. V , in the yz plane, M=M H ×M V An electromagnetic unit is used. When applied, the user equipment sends a pilot signal, and the intelligent metasurface regularly scans the beam to assist the UE-RIS-BS in uplink transmission. The transmission is carried out in combination with a specific target codebook, that is, different orthogonal angle pairs are used for uplink transmission. Then the base station evaluates the quality of the received pilot signal, calculates the optimal beam direction, and feeds back the precoding matrix to the intelligent metasurface to determine the target angle pair. By using the reciprocity of the angle, the uplink channel angle information is used for downlink signal transmission. After the intelligent metasurface obtains the corresponding downlink channel, it assists the BS-RIS-UE in downlink transmission.

[0053] Furthermore, considering the passive working mode of RIS, RIS cannot directly send or receive pilot signals. Either the base station or the user sends them. It is necessary to directly estimate the cascade (two-segment) channel assisted by RIS. The UE sends a pilot signal to the BS. RIS changes its reflection coefficient in real time according to the pre-designed reflection pattern (such as codebook) to assist in cascade channel estimation. However, the complexity of channel estimation and the required resources will increase with the increase in the number of RIS electromagnetic units. During the channel estimation process, RIS needs to try more beam direction combinations to find the best beam direction, which will lead to an increase in training time. The more combinations, the longer the training time, so the codebook needs to be reduced. Therefore, the codebook dimension and the use of 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 in the embodiment of the present invention will be described in detail below with the smart metasurface as the execution subject in combination with the drawings in the embodiment of the present invention.

[0055] Specifically, see Figure 2 In one embodiment of the invention, the intelligent metasurface cascade channel estimation method of the present invention comprises the following steps:

[0056] Step S202, receiving a pilot signal sent by a user equipment;

[0057] Step S204, uplink transmitting the pilot signal 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 a plurality of angle pairs consisting of azimuth angles and elevation angles in the smart metasurface subspace;

[0058] Step S206, receiving the precoding matrix fed back by the base station and extracting it in combination with the target codebook to obtain a target angle pair, wherein the target angle pair is an uplink / downlink channel;

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

[0060] It should be noted that in this embodiment, when transmitting data, the direct link between the BS and the UE is interrupted due to the obstruction of obstacles and cannot carry data transmission services. Therefore, the RIS is deployed within the line of sight of the BS and the UE. By regulating the reflection of the BS transmission signal, the BS can resume providing data transmission services to the UE. The UEs are 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, it is necessary to perform channel estimation before data transmission. This embodiment will further explain how to perform channel estimation based on the intelligent metasurface.

[0061] Specifically, the user repeatedly sends several pilot signals to the base station within a preset time range, and the intelligent metasurface periodically scans different beam directions based on the preset target code book to assist the base station in receiving the beam signal reflected by the intelligent metasurface, that is, it corresponds to first receiving the pilot signal sent by the user equipment, and then reflecting and transmitting the pilot signal using several angle pairs in the target code book, and transmitting it to the base station in an uplink manner, wherein the number of pilot signals is consistent with the number of angle pairs, and then the base station determines the optimal beam direction according to the quality of the received uplink pilot signal, and feeds back a precoding matrix to the intelligent metasurface, which includes the optimal angle pair. Therefore, after the intelligent metasurface receives the precoding matrix fed back by the base station, it can extract the target angle pair in combination with the target code book, and accordingly, the target angle pair is an uplink / downlink channel, so that during downlink transmission, the base station data sent by the base station can be downlinked to the user equipment based on the downlink channel.

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

[0063] Initializing a Collection With Collection is an empty set;

[0064] The elevation angle set Θ of the spatial dimension is calculated based on the intelligent metasurface;

[0065] Setting θ i ∈Θ, calculate the azimuth set Φ(θ i );

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

[0067] Based on the updated collection Collect orthogonal angle pairs in the channel subspace of the smart metasurface To update the collection Among them, i is the angle number.

[0068] It should be noted that, in this embodiment, the channel coefficients of adjacent RIS units are similar, which is determined by the number of clusters (assuming independent subpaths with the same delay) and their angular distribution in the propagation environment. For a RIS with a typical planar structure and sub-wavelength units, there will be a large amount of spatial correlation under isotropic scattering, where the spatial correlation is explained 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, and the subspace dimension is approximately equal to the number of eigenvalues). In order to consider minimizing the search space during pilot transmission, a set of azimuth-elevation pairs must first be found. These angle pairs will constitute an orthogonal basis for the RIS channel. Specifically, assuming aRIS (π / 2,0) is the component of the angle pair, with a RIS (π / 2,0) is the reference point, and all vectors that can produce mutually orthogonal array responses are searched.

[0069] First, according to The expression can be and The resulting array response inner product is written as:

[0070]

[0071] Among them, M V is the electromagnetic unit configured on the smart metasurface in the z direction, d V is the configuration interval of the electromagnetic unit in the z direction, k is the serial number of the electromagnetic unit configured on the smart metasurface in the z direction, M H is the electromagnetic unit configured on the smart metasurface in the y direction, d H is the configuration interval of the electromagnetic unit in the y direction, l is the serial number of the electromagnetic unit configured on the smart metasurface in the z direction,

[0072]

[0073] therefore, and T(Ψ) can be rewritten as:

[0074]

[0075] Here, the corner pairs that produce mutually orthogonal array responses are collected, that is, Therefore, you need to search separately The elevation angle set, and the azimuth angle set where T(Ψ)=0.

[0076] Further, in one embodiment of the invention, calculating the elevation angle set θ of the spatial dimension specifically includes:

[0077] The elevation angle set Θ is calculated based on the preset elevation angle calculation expression. The elevation angle calculation expression is as follows:

[0078]

[0079] Among them, M V is the electromagnetic unit configured on the smart metasurface in the z direction, d V is the configuration interval of the smart metasurface in the z direction, and k is the serial number of the electromagnetic units configured on the smart metasurface in the z direction.

[0080] It should be noted that in this embodiment, the specific calculation The elevation angle set at , where where k = ±1,…,±(M V -1), that is can be regarded as a periodic function with a period of Assuming (π / 2,0) is a component of the angle pair, that is, taking θ1=0 as the reference point, looking for other elevation angles within the period can satisfy Right now By solving A set of mutually orthogonal elevation angles can be obtained, and further where k = ±1,…,±(M V -1), where the elevation angle set Θ = {θ1,…,θ n}, where M V is the electromagnetic unit configured on the smart metasurface in the z direction, d V is the configuration interval of the smart metasurface in the z direction, and k is the serial number of the electromagnetic units configured on the smart metasurface in the z direction.

[0081] Furthermore, in one embodiment of the invention, the azimuth angle set Φ(θ i ), including:

[0082] Calculate the elevation angle set Φ(θ based on the preset azimuth calculation expression i ), the azimuth angle calculation expression is as follows:

[0083]

[0084] Among them, M H is the electromagnetic unit configured on the smart metasurface in the y direction, d H is the configuration interval of the smart metasurface in the y direction, l is the serial number of the electromagnetic units configured in the smart metasurface in the z direction, θ i is the elevation angle, is the azimuth, and i is the angle number.

[0085] It should be noted that, in this embodiment, the azimuth angle 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 Since the assumption a RIS (π / 2,0) is the component of the angle pair, that is, As the reference point, look for other azimuths within the period that can satisfy T(Ψ)=0, that is, To further collect i All azimuths corresponding to the relevant orthogonal beams, where the azimuth set Among them, M His the electromagnetic unit configured on the smart metasurface in the y direction, d H is the configuration interval of the smart metasurface in the y direction, l is the serial number of the electromagnetic units configured in the smart metasurface in the z direction, θ i is the elevation angle, is the azimuth, and i is the angle number.

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

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

[0088] The collection to be initialized Merge the elements with the corner pair to obtain an updated set Where η is the subspace dimension of the smart metasurface.

[0089] Further, in one embodiment of the invention, based on the updated set Collect orthogonal angle pairs in the channel subspace of the smart metasurface To update the collection Specifically include:

[0090] Combine the sets based on the angle pair expression Collect all orthogonal array response vectors

[0091] The collection to be initialized Merge the elements with the orthogonal array response vector to obtain an updated set Among them, i is the angle number and η is the subspace dimension of the smart hypersurface.

[0092] It should be noted that in this embodiment, since the set is initialized in advance With Collection is an empty set. After gradually obtaining the elevation angle set Θ and the azimuth angle set Φ, they need to be updated by element merging. Specifically, the elevation angle set Θ = {θ1,…,θ n}, azimuth set n is the number of all angles. Since the dimension of the subspace of the smart hypersurface will decrease, specifically to η, the angle pairs obtained by extracting all azimuth and elevation angles are Then initialize the collection Merge the elements with the corner pair to obtain an updated set Further, based on the angle pair expression combined with the set Collect all orthogonal array response vectors in, is the angle pair expression. The specific calculation process is known to those skilled in the art and will not be described in detail here. Then, the initialized set Merge the elements with the orthogonal array response vector to obtain an updated set Where i is the angle number, η is the subspace dimension of the smart hypersurface, and the target codebook is finally obtained, which is specifically an orthogonal array response set of the subspace dimension of the smart hypersurface, where the subspace dimension

[0093] The embodiment of the present application also provides an intelligent metasurface, the intelligent metasurface comprising a processor and a reflective surface, wherein the reflective surface is electrically connected to the processor, and the processor implements any one of the intelligent metasurface cascade channel estimation methods when executed, and at the same time, the reflective surface of the intelligent metasurface is a uniform rectangular array, and M are configured in the y direction. H The electromagnetic units are arranged at intervals of d in the y direction. H , M is configured in the z direction V The electromagnetic units are arranged at intervals of d in the z direction. V , in the yz plane, M=M H ×M V Electromagnetic unit.

[0094] It should be noted that, in this embodiment, Figure 1 As shown, it is specifically described that the composition of the intelligent metasurface includes a processor and a reflective surface, which can be specifically connected by a cable or optical fiber, wherein the reflective surface of the RIS is composed of a large number of reflective units (usually electrical components made of electromagnetic materials), which can adjust the characteristics of the reflected wave according to the control signal, including phase, amplitude, etc. The working state of each reflective unit (such as phase adjustment) will directly affect the propagation path and signal strength of the signal, thereby achieving enhancement, orientation or suppression of the wireless signal, and each reflective unit can independently adjust the phase or amplitude of the reflected signal, and the processor is responsible for controlling the operation of all reflective units to achieve the desired signal adjustment effect, wherein, 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 (for example, 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 function, specifically coordinating the work of multiple reflective units to ensure that the propagation of the signal achieves the best effect.

[0095] Furthermore, since the specific implementation of the execution process of the processor 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 gates or transistor logic devices, discrete hardware components.

[0097] In the several embodiments provided by the present invention, it should be understood that the disclosed system or method can be implemented in other ways. For example, the system embodiments described above are only schematic, for example, the division of modules / units is only a logical function division, and there may be other division methods in actual implementation, such as multiple modules or units can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or modules or units, which can be electrical, mechanical or other forms.

[0098] The modules / units described as separate components may or may not be physically separated, and the components displayed as modules / units may or may not be physical modules, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules / units may be selected according to actual needs to achieve the purpose of the embodiments of the present invention. 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 of ordinary skill in the art should further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0100] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A smart metasurface cascade channel estimation method, characterized in that: include: receiving a pilot signal sent by a user equipment; Uplink transmitting the pilot signal to a 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 a plurality of angle pairs consisting of azimuth angles and elevation angles in a smart metasurface subspace; Receive the precoding matrix fed back by the base station and extract it in combination with the target codebook to obtain a target angle pair, wherein the target angle pair is an uplink / downlink channel; The base station data sent by the base station is downlink transmitted to the user equipment based on a downlink channel.

2. The intelligent metasurface cascade channel estimation method according to claim 1, characterized in that: The step of generating the target codebook specifically includes: Initializing a Collection With Collection is an empty set; The elevation angle set Θ of the spatial dimension is calculated based on the intelligent metasurface; Setting θ i ∈Θ, calculate the azimuth set Φ(θ i ); Based on the elevation angle set Θ and the azimuth angle set Φ, collect the orthogonal angle pairs Update Collection Based on the updated collection Collect orthogonal angle pairs in the channel subspace of the smart metasurface To update the collection Among them, i is the angle number.

3. The intelligent metasurface cascade channel estimation method according to claim 2, characterized in that: The target codebook is an orthogonal array response set of the subspace dimension of the intelligent metasurface, where the subspace dimension 4. The intelligent metasurface cascade channel estimation method according to claim 2, characterized in that: Calculate the elevation angle set Θ of the spatial dimension, specifically including: The elevation angle set Θ is calculated based on the preset elevation angle calculation expression. The elevation angle calculation expression is as follows: where k = ±1,…,±(M V -1)}; Among them, M V is the electromagnetic unit configured on the smart metasurface in the z direction, d V is the configuration interval of the smart metasurface in the z direction, and k is the serial number of the electromagnetic units configured on the smart metasurface in the z direction.

5. The intelligent metasurface cascade channel estimation method according to claim 4, characterized in that: Calculate the azimuth set Φ(θ i ), including: Calculate the elevation angle set Φ(θ based on the preset azimuth calculation expression i ), the azimuth angle calculation expression is as follows: Among them, M H is the electromagnetic unit configured on the smart metasurface in the y direction, d H is the configuration interval of the smart metasurface in the y direction, l is the serial number of the electromagnetic units configured in the smart metasurface in the z direction, θ i is the elevation angle, is the azimuth, and i is the angle number.

6. The intelligent metasurface cascade channel estimation method according to claim 5, characterized in that: Based on the elevation angle set Θ and the azimuth angle set Φ, collect the orthogonal angle pairs Update Collection Specifically include: Extract all azimuth and elevation angles to get angle pairs The collection to be initialized Merge the elements with the corner pair to obtain an updated set Where η is the subspace dimension of the smart metasurface.

7. The intelligent metasurface cascade channel estimation method according to claim 6, characterized in that: Based on the updated collection Collect orthogonal angle pairs in the channel subspace of the smart metasurface To update the collection Specifically include: Combine the sets based on the angle pair expression Collect all orthogonal array response vectors The collection to be initialized Merge the elements with the orthogonal array response vector to obtain an updated set Among them, i is the angle number and η is the subspace dimension of the smart hypersurface.

8. A smart metasurface, characterized in that: It includes a processor, which, when executed, implements the intelligent metasurface cascade channel estimation method according to any one of claims 1 to 7.

9. The smart supersurface according to claim 8, characterized in that: 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, and M is configured in the y direction. H The electromagnetic units are arranged at intervals of d in the y direction. H , M is configured in the z direction V The electromagnetic units are arranged at intervals of d in the z direction. V , in the yz plane, M=M H ×M V An electromagnetic unit.

10. An intelligent metasurface cascade channel estimation system, characterized in that: include: User equipment, used to send out pilot signals and receive base station data; The smart metasurface according to claim 8, is used to determine a plurality of angle pairs consisting of azimuth and elevation angles in a smart metasurface subspace, and use the plurality of angle pairs to uplink the pilot signal to a base station, and receive a precoding matrix fed back by the base station to determine a target angle pair, and downlink the base station data sent by the base station to the user equipment based on a downlink channel, wherein: The target angle pair is an uplink / downlink channel; A base station is used to receive different beam signals transmitted from several angle pairs and evaluate the corresponding signal quality to determine the best beam direction, and to feed back a precoding matrix based on the best beam direction, and to send out the base station data.

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