A Low-Complexity Phase Setting Method for a Single-Antenna System Assisted by Intelligent Reflecting Surfaces

Abstract

The present invention discloses a low-complexity phase setting method for a single-antenna system assisted by an intelligent reflecting surface. This method is applicable to a system where a single antenna is configured at the transmitter and the receiver respectively, and an intelligent reflecting surface is deployed to assist communication. Each unit of the deployed intelligent reflecting surface can be independently configured with a phase shift value and has a discrete phase shift resolution of q bits. The method includes the following steps: Calculate the electromagnetic wave path lengths of each segment of the transmitter-intelligent reflecting surface-receiver according to the position information of the transmitter and the receiver; Calculate the ideal continuous phase of the intelligent reflecting surface according to the electromagnetic wave path lengths; Design a quantization threshold to convert the obtained ideal continuous phase into a discrete phase that can be actually configured by the intelligent reflecting surface. This method can ensure the quality of the received signal with relatively low phase design complexity, can effectively improve the channel quality of the intelligent reflecting surface-assisted single-antenna communication system, and has strong practicability and high effectiveness.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and mainly relates to a low-complexity phase setting method for a single-antenna system assisted by an intelligent reflecting surface. Background Art

[0002] In recent years, wireless communication systems have witnessed rapid development. Scholars have proposed various communication technologies, such as large-scale antenna arrays, relay transmission, etc., to improve the channel quality. However, the above technologies all have their inherent defects in the actual deployment process, such as high power consumption, high hardware complexity and cost.

[0003] With the rapid development of metamaterials and radio frequency microelectromechanical systems, intelligent reflecting surfaces are expected to be widely applied in future wireless communication systems. By intelligently regulating the propagation mode of electromagnetic signals, intelligent reflecting surfaces provide a new perspective for next-generation mobile communications. At the same time, the introduction of intelligent reflecting surfaces has brought revolutionary changes to traditional wireless communications, attracting extensive attention from scholars. An intelligent reflecting surface is a two-dimensional surface composed of a large number of adjustable reflecting units. Each reflecting unit consists of a control circuit (for configuring the phase shift of the unit) and a metal patch. Each reflecting unit can generate an independent phase shift for the incident signal, so as to enable real-time control of the beamforming of the reflected signal to enhance the electromagnetic field strength. In this way, the intelligent reflecting surface can actively regulate the propagation environment of the wireless channel, providing a new paradigm for next-generation wireless communications. Due to the passive characteristics of the intelligent reflecting surface, it only reflects the incident signal and does not generate new signals. Therefore, it does not require the use of expensive radio frequency chains, saving costs and not introducing additional power consumption, meeting the requirements of current green communications and sustainable development.

[0004] Currently, the phase design for an intelligent reflecting surface-assisted single-antenna system is still in the exploratory stage. The existing phase design algorithms: 1) only focus on continuous phase design and ignore the discrete phases in practical applications; 2) the algorithm complexity is too high, for example, the traversal algorithm has exponential complexity; 3) low complexity cannot guarantee the beamforming performance. Therefore, for an intelligent reflecting surface-assisted single-antenna system, a discrete phase design algorithm that can achieve high communication performance with low computational complexity and has high practicality is worthy of further exploration. Summary of the Invention

[0005] Technical problem: The present invention proposes a low-complexity phase shift matrix calculation method for the discrete phase design problem of an intelligent reflecting surface-assisted single-antenna system. First, according to the position information of the transmitter, the intelligent reflecting surface, and the receiver, calculate the electromagnetic wave path lengths from the transmitter to each unit of the intelligent reflecting surface and then to the receiver. Secondly, calculate the ideal continuous phase shift configuration of each unit of the intelligent reflecting surface based on the electromagnetic wave path lengths. Subsequently, calculate the quantization threshold set according to the ideal continuous phase shift configuration from the transmitter to each unit of the intelligent reflecting surface and then to the receiver, traverse the elements in the quantization threshold set, and calculate the corresponding electromagnetic field strength. Select the quantization threshold with the maximum electromagnetic field strength, and use the discrete phase shift under this quantization threshold as the configured phase shift of the intelligent reflecting surface.

[0006] Technical solution: To achieve the above object, the present invention proposes a low-complexity phase design method for an intelligent reflecting surface-assisted single-antenna system, with a single antenna configured at the transmitter and the receiver respectively, and an intelligent reflecting surface is deployed between the transmitter and the receiver to assist communication; the deployed intelligent reflecting surface is composed of M rows and N columns of reflection units, that is, a total of M×N reflection units, and each unit can be independently configured with a phase offset, i.e., a phase shift value; each unit has a discrete phase shift resolution of q bits, and its possible 2 q discrete phase shift value set is where ρ p represents the p-th possible discrete phase shift value, p = 1, 2,..., 2 q , and the relationship between the p-th discrete phase shift value and the first discrete phase shift value is The value of ρ1 is determined by the hardware design of the intelligent reflecting surface.

[0007] The method specifically includes the following steps:

[0008] Step 1, for the reflection unit in the m-th row, m = 1,..., M, and the n-th column, n = 1,..., N, of the intelligent reflecting surface, use the following formula to calculate the distance between the transmitter and this intelligent reflecting surface and the distance between the receiver and this intelligent reflecting surface

[0009]

[0010]

[0011] where d1 is the distance between the transmitter and the center of the intelligent reflecting surface, d2 is the distance between the receiver and the center of the intelligent reflecting surface, θ t , θ r , They are respectively the elevation angle of the transmitting end relative to the center of the intelligent reflecting surface, the azimuth angle of the transmitting end relative to the center of the intelligent reflecting surface, the elevation angle of the receiving end relative to the center of the intelligent reflecting surface, the azimuth angle of the receiving end relative to the center of the intelligent reflecting surface, and d x and d y They are respectively the transverse dimension and the longitudinal dimension of each unit of the intelligent reflecting surface;

[0012] Step 2, calculate the ideal continuous phase shift matrix of the intelligent reflecting surface where represents the complex matrix space of M rows and N columns, and the element in its m-th row and n-th column is the ideal continuous phase shift φ m,n ;

[0013] Step 3, calculate the quantization threshold γ for converting the continuous phase shifts of each unit of the intelligent reflecting surface into discrete phase shifts;

[0014] Step 4, based on the ideal continuous phase shift matrix of the intelligent reflecting surface, use the quantization threshold γ to quantize it into a configurable discrete phase shift matrix in the actual situation The element in its m-th row and n-th column, Δ m,n is the discrete phase shift of the reflecting unit in the m-th row and n-th column, and its calculation method is:

[0015]

[0016] where,

[0017] where,

[0018] The calculation of the quantization threshold described in Step 3 includes the following steps:

[0019] Step S1: According to the ideal continuous phase shift matrix Φ obtained in Step 2, calculate the quantization threshold matrix The element in its m-th row and n-th column is denoted as γ m,n ;

[0020] Step S2: Let x = 1; ξ = 0;

[0021] Step S3: Let y = 1;

[0022] Step S4: Using the element γ x,y in the x-th row and y-th column of the quantization threshold matrix Γ as the quantization threshold, quantize the ideal continuous phase shift matrix Φ obtained in Step 2 into a discrete phase shift matrix using the method of Step 4

[0023] Step S5: Calculate the electromagnetic field strength ξ x,y under the quantization threshold of γ x,y :

[0024]

[0025] Step S6: If ξ x,y > ξ, then let ξ = ξ x,y , γ = γ x,y , and enter Step S7; otherwise, directly enter Step S7;

[0026] Step S7: If y < N, then let y = y + 1 and enter Step S4; otherwise, enter Step S8;

[0027] Step S8: If x < M, then let x = x + 1 and enter Step S3; otherwise, the algorithm ends and outputs the quantization threshold γ.

[0028] In the said Step 2, the ideal continuous phase shift matrix of the intelligent reflecting surface The element φ at the m-th row and n-th column m,n is calculated by the following method:

[0029]

[0030] where λ is the carrier wavelength.

[0031] In the said Step S1, the quantization threshold matrix Its element γ at the m-th row and n-th column m,n is calculated by the following method:

[0032]

[0033] Beneficial effects: The algorithm provided by the present invention has the following advantages.

[0034] (1) The present invention is applicable to a variety of communication scenarios and has universality for the phase alignment and beamforming problems in the intelligent reflecting surface-assisted single-antenna wireless communication system;

[0035] (2) The discrete phase calculation method in the present invention: In the ideal case, it has optimality for the beamforming effect in the intelligent reflecting surface-assisted single-antenna system; in the actual communication environment, it also approaches the performance upper limit of the intelligent reflecting surface beamforming in the discrete domain;

[0036] (3) The intelligent reflecting surface discrete phase shift calculation method designed by the present invention has low complexity and only has linear complexity, ensuring its applicability in the actual environment.

[0037] Compared with the existing phase design algorithms, the algorithm proposed in the present invention can not only reduce the computational complexity but also ensure the performance advantage, and approaches optimality in the actual application environment. Therefore, it has practicability and high efficiency in the intelligent reflecting surface-assisted single-antenna communication system. Description of the Drawings

[0038] Figure 1 This is a schematic diagram of a low-complexity phase setting method in a smart reflecting surface-assisted single-antenna system proposed by the present invention for a smart reflecting surface with 1-bit phase resolution. Detailed implementation manners

[0039] The present invention will be further described in conjunction with the accompanying drawings.

[0040] The present invention relates to a low-complexity phase setting method in a smart reflecting surface-assisted single-antenna system. Consider a smart reflecting surface-assisted single-antenna system, where a single antenna is configured at the transmitter and the receiver respectively; the smart reflecting surface consists of M rows and N columns of reflecting units, that is, a total of M×N reflecting units. In the present invention, a cascaded channel of transmitter-smart reflecting surface-receiver is considered. Based on improving the channel quality and strengthening the beamforming effect, the following phase design scheme is made:

[0041] The transmitter transmits an electromagnetic wave signal to the smart reflecting surface. After the smart reflecting surface performs appropriate phase shift configuration, it will reflect the electromagnetic wave signal to the receiver. In this process, the appropriate phase shift configuration of the smart reflecting surface will significantly improve the channel quality and strengthen the beamforming effect. Therefore, first, according to the position information of the transmitter, the smart reflecting surface, and the receiver, the wave path of each electromagnetic wave in the channel is calculated. Based on the wave path of the electromagnetic wave, the continuous phase shift matrix of each unit of the smart reflecting surface is calculated. Subsequently, based on the continuous phase shift matrix, a candidate quantization threshold set is generated for converting the continuous phase into a discretized phase shift that can be actually configured. Traverse the elements in the quantization threshold set to find the element that maximizes the electromagnetic field strength. The discretized phase shift calculated under this quantization threshold element is used as the configuration of the smart reflecting surface.

[0042] The present invention solves the problem of the discretized phase shift configuration in the deployment of smart reflecting surface-assisted communication. Compared with traditional algorithms, such as exhaustive search, the method in the present invention effectively reduces the algorithm complexity while ensuring that the beamforming performance of the smart reflecting surface approaches the upper bound in the actual communication environment, and has practicality and high efficiency.

[0043] To make the technical solutions in the present invention clearer, the present solution will be specifically described below. For a smart reflecting surface with 1-bit phase resolution, the technical solution embodiments provided in the present invention are as Figure 1 shown. Among them, a single antenna is configured at the transmitter and the receiver respectively, and a smart reflecting surface is deployed between the transmitter and the receiver to assist communication; the deployed smart reflecting surface consists of 32 rows and 16 columns of reflecting units, that is, a total of 32×16 reflecting units, and each unit can independently configure the phase offset (phase shift) value; each unit has a 1-bit discrete phase shift resolution, and its set of 2 possible discrete phase shift values is Among them, ρ1 = 0 and ρ2 = π represent the first and second discrete phase shift values respectively, which are determined by the hardware design of the intelligent reflecting surface. The method includes the following steps:

[0044] Step 1: Consider the distance d1 = 10 meters between the transmitter and the center of the intelligent reflecting surface, the distance d2 = 10 meters between the receiver and the center of the intelligent reflecting surface, the elevation angle θ of the transmitter relative to the center of the intelligent reflecting surface t = π / 4, the azimuth angle of the transmitter relative to the center of the intelligent reflecting surface The elevation angle θ of the receiver relative to the center of the intelligent reflecting surface r = π / 4, the azimuth angle of the receiver relative to the center of the intelligent reflecting surface The lateral dimension d of each unit of the intelligent reflecting surface x and the longitudinal dimension d y are both 0.05 meters. The electromagnetic wave frequency is 2.6 GHz, and the wavelength λ = [3×10 8 / (2.6×10 9 )] meters.

[0045] For the reflection unit in the m-th row (m = 1,..., 32) and n-th column (n = 1,..., 16) of the intelligent reflecting surface, the following formula is used to calculate the distance between the transmitter and it and the distance between the receiver and it

[0046]

[0047]

[0048] Step 2: Calculate the ideal continuous phase shift matrix of the intelligent reflecting surface Among them represents the complex matrix space of 32 rows and 16 columns, and the element in the m-th row and n-th column is the ideal continuous phase shift φ m,n of the reflection unit in the m-th row and n-th column, and its calculation method is:

[0049]

[0050] Step 3: Calculate the quantization threshold γ for converting the continuous phase shift of each unit of the intelligent reflecting surface into a discrete phase shift according to the following steps:

[0051] Step S1: According to the ideal continuous phase shift matrix Φ obtained in Step 2, calculate the quantization threshold matrix The element γ in its m-th row and n-th column m,n is calculated in the following way:

[0052]

[0053] Step S2: Let x = 1; ξ = 0;

[0054] Step S3: Let y = 1;

[0055] Step S4: Using the element γ at the x-th row and y-th column in the quantization threshold matrix Γ as the quantization threshold, quantize the ideal continuous phase shift matrix Φ obtained in Step 2 into a discrete phase shift matrix using the method in Step 4 x,y

[0056] Step S5: Calculate the electromagnetic field strength ξ with the quantization threshold γ using the following formula x,y x,y :

[0057]

[0058] Step S6: If ξ x,y > ξ, then let ξ = ξ x,y , γ = γ x,y , and go to Step S7; otherwise, directly go to Step S7;

[0059] Step S7: If y < 16, then let y = y + 1 and go to Step S4; otherwise, go to Step S8;

[0060] Step S8: If x < 32, then let x = x + 1 and go to Step S3; otherwise, the algorithm ends and outputs the quantization threshold γ.

[0061] Step 4: Based on the ideal continuous phase shift matrix of the intelligent reflecting surface, using the quantization threshold γ, quantize it into a discretely configurable phase shift matrix in the actual situation The element Δ at its m-th row and n-th column m,n is the discrete phase shift of the reflecting unit at the m-th row and n-th column, and its calculation method is:

[0062]

[0063] The above is only the preferred embodiment of the present invention. It should be noted that: for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.​​

Claims

1. A low-complexity phase setting method for a single-antenna system assisted by an intelligent reflecting surface, characterized in that: Configure a single antenna at the transmitter and receiver respectively, and deploy an intelligent reflecting surface between the transmitter and receiver to assist communication; the deployed intelligent reflecting surface consists of M rows and N columns of reflecting units, that is, a total of M×N reflecting units, and each unit can be independently configured with a phase offset, that is, a phase shift value; each unit has a discrete phase shift resolution of q bits, and its possible 2 q sets of discrete phase shift values are where ρ p represents the p-th possible discrete phase shift value, p = 1, 2,..., 2 q , and the relationship between the p-th discrete phase shift value and the first discrete phase shift value is The value of ρ1 is determined by the hardware design of the intelligent reflecting surface; The method specifically includes the following steps: Step 1: For the reflection unit in the \(m\)-th row (\(m = 1,\cdots,M\)) and \(n\)-th column (\(n = 1,\cdots,N\)) of the intelligent reflecting surface, calculate the distance between the transmitting end and the intelligent reflecting surface using the following formula and the distance between the receiving end and the intelligent reflecting surface where d1 is the distance between the transmitting end and the center of the intelligent reflecting surface, d2 is the distance between the receiving end and the center of the intelligent reflecting surface, θ t , θ r , are respectively the elevation angle of the transmitting end relative to the center of the intelligent reflecting surface, the azimuth angle of the transmitting end relative to the center of the intelligent reflecting surface, the elevation angle of the receiving end relative to the center of the intelligent reflecting surface, and the azimuth angle of the receiving end relative to the center of the intelligent reflecting surface, d x and d y are respectively the transverse dimension and the longitudinal dimension of each unit of the intelligent reflecting surface; Step 2, calculate the ideal continuous phase shift matrix of the intelligent reflecting surface where represents the complex matrix space of M rows and N columns, and the element in the m-th row and n-th column is the ideal continuous phase shift φ of the reflecting element in the m-th row and n-th column m,n ; Step 3: Calculate the quantization threshold γ for converting the continuous phase shifts of each unit of the intelligent reflecting surface into discrete phase shifts; Step 4: Based on the ideal continuous phase shift matrix of the intelligent reflecting surface, using the quantization threshold γ, it is quantized into a discretized phase shift matrix that can be configured in the actual situation The element Δ in its m-th row and n-th column m,n is the discrete phase shift of the reflecting element in the m-th row and n-th column, and its calculation method is as follows: Among them, 2. The low-complexity phase setting method for a single-antenna system assisted by an intelligent reflecting surface according to claim 1, wherein The calculation of the quantization threshold described in Step 3 includes the following steps: Step S1. Calculate the quantization threshold matrix according to the ideal continuous phase shift matrix Φ obtained in step 2 The element in the m-th row and n-th column is denoted as γ m,n ; Step S2: Let x = 1; ξ = 0; Step S3: Let y = 1; Step S4: Using the element γ at the x-th row and y-th column in the quantization threshold matrix Γ x,y as the quantization threshold, quantize the ideal continuous phase shift matrix Φ obtained in Step 2 into a discrete phase shift matrix using the method in Step 4 Step S5. Calculate the electromagnetic wave field strength ξ under the quantization threshold γ using the following formula x,y x,y :​ Step S6: If ξ x,y > ξ, then let ξ = ξ x,y , γ = γ x,y , and proceed to Step S7; otherwise, directly proceed to Step S7; Step S7: If y < N, then let y = y + 1 and go to Step S4; otherwise go to Step S8; Step S8: If x < M, then let x = x + 1 and go to Step S3; otherwise the algorithm ends and outputs the quantization threshold γ.

3. The low-complexity phase setting method for the intelligent reflecting surface-assisted single-antenna system according to claim 1, wherein: In the said step 2, the ideal continuous phase shift matrix of the intelligent reflecting surface The element φ in the m-th row and n-th column m,n is calculated by the following method: Where λ is the carrier wavelength.

4. The low-complexity phase setting method for a single-antenna system assisted by an intelligent reflecting surface according to claim 2, wherein: The quantization threshold matrix in the step S1 The element γ in the m-th row and n-th column thereof m,n is calculated by the following method:

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