Channel estimation method and system for flow antenna assisted symbiotic communication system

Abstract

The invention discloses a channel estimation method and system for a flow-state antenna-assisted symbiotic communication system, and the method comprises the steps: arranging a base station, a user and a backscattering device for the flow-state antenna-assisted symbiotic communication system, and installing a flow-state antenna on the base station to assist transmission; the uplink pilot frequency transmission is divided into two stages, and in the two stages, the user and the backscattering device send pilot frequency signals to the base station; carrying out matrix processing on the direct link channel and the backscattering link channel, and converting the direct link channel and the backscattering link channel into Vandermonde matrixes; a channel is obtained based on the converted Vandermonde matrix, and channel estimation is performed on a direct link and a backscattering link by using a least square regression method; according to the invention, channel estimation can be carried out more accurately, the signal processing complexity is lower, and the requirement on system hardware is reduced.

Description

Technical Field

[0001] The present invention relates to a channel estimation method and system, and in particular to a channel estimation method and system for a symbiotic communication system assisted by a flow antenna, belonging to the technical field of wireless communications. Background Art

[0002] Symbiotic communication is a promising technology that incorporates backscatter devices to aid transmission. Backscatter devices modulate information onto a continuous wave signal generated by a dedicated carrier transmitter, significantly reducing the communication power required for transmission. Furthermore, backscatter devices lack active transmitter components, reducing equipment cost and energy consumption. However, backscatter devices are typically small, equipped with only a single antenna, and often exhibit weak diversity gain, significantly impacting system performance and reducing power and spectral efficiency.

[0003] To this end, a new technology called fluidic antennas has been proposed. These represent any software-controlled fluid, conductive, or dielectric structure that can dynamically change its shape and position to reconfigure its fundamental RF characteristics. This allows small-scale communication devices to break through spatial limitations and achieve good diversity. Therefore, symbiotic communication systems assisted by fluidic antennas have great potential. However, current symbiotic communication systems assisted by fluidic antennas still have some problems. One typical issue is the lack of a suitable channel estimation solution, resulting in low channel estimation accuracy and precluding practical application. Summary of the Invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a channel estimation method and system for a symbiotic communication system assisted by a flow antenna, which can improve the accuracy of channel estimation.

[0005] Technical solution: The present invention provides a channel estimation method for a symbiotic communication system assisted by a flow antenna, comprising:

[0006] (1) A symbiotic communication system assisted by a flow antenna is configured with a base station, a user, and a backscatter device. A flow antenna is installed on the base station to assist transmission. The link from the base station to the user is a direct link, and the link from the base station to the backscatter device and then to the user is a backscatter link.

[0007] (2) Implementing uplink pilot transmission, including: in the first stage, the user sends a pilot signal to the base station, and at the same time, the backscatter device sends the same pilot signal to the base station; in the second stage, the user sends the pilot signal to the base station again, and the backscatter device modulates the amplitude of the signal and then sends the signal to the base station;

[0008] (3) The base station performs mixed elimination calculation processing on the signals received in the two stages;

[0009] (4) Matrix processing is performed on the direct link channel and the backscatter link channel, and they are converted into Vandermonde matrices;

[0010] (5) Based on the channel obtained after conversion to the Vandermonde matrix, the least squares regression method is used to estimate the channel for the direct link and the backscatter link respectively.

[0011] Furthermore, the step (1) includes:

[0012] A movable flow antenna is installed at the base station end, and z = [x, y] represents the local coordinates of the flow antenna carried by the base station, L Tx represents the number of flow antenna ports, Represents the corresponding matrix of the transmission field from the base station to the user, j is an imaginary number, λ is the carrier wavelength, ρ TR,l (z) = x sin θ TR,l cosφ TR,l +ycosθ TR,l represents the signal propagation distance difference of the lth port of the flow-state antenna on the direct link, θ TR,l ∈[0,π] and φ TR,l ∈[0,π] represent the elevation angle and azimuth angle of the lth port of the direct link upper stream antenna, represents the path response vector from the base station to the user, and the direct link channel h is expressed as:

[0013]

[0014] make represents the corresponding matrix of the transmission field from the base station to the backscatter device and then to the user, ρ BR,l (z) = x sin θ BR,l cosφ BR,l +ycosθ BR,l represents the signal propagation distance difference of the lth port of the upstream antenna on the backscatter link, θ BR,l ∈[0,π] and φ BR,l ∈[0,π] represent the elevation angle and azimuth angle of the lth port of the upstream antenna on the backscatter link, represents the path response vector from the base station to the backscatter device and then to the user. The backscatter link channel g can be expressed as:

[0015]

[0016] Furthermore, the step (2) includes:

[0017] (21) In the first stage, the user sends a pilot signal to the base station. At the same time, the backscattering device sends the same pilot signal to the base station. At this time, the first stage signal y1 received by the base station is:

[0018]

[0019] Where p is the power of the signal sent by the user, is a pilot signal and satisfies α is the modulation coefficient of the backscatter device, w1 is the noise received by the base station in the first stage, and is subject to a mean of 0 and a variance of σ 2 The normal distribution, σ 2 is the noise power; after the base station receives the signal, it does not perform any processing and directly goes to the second stage;

[0020] (22) In the second stage, the user sends a pilot signal to the base station again. The backscattering device modulates the amplitude of the signal and then sends the signal to the base station. At this time, the second stage signal y2 received by the base station is

[0021]

[0022] Where w2 is the noise received by the base station in the first stage, which has a mean of 0 and a variance of σ 2 Normal distribution.

[0023] Furthermore, the step (3) includes:

[0024] Based on the received signals of the two phases, the base station obtains the following equations:

[0025]

[0026] The base station performs mixed elimination calculation processing to obtain the processed first stage signal and the processed second stage signal

[0027]

[0028] Then, the base station converts the pilot signal into Put it on the original signal, and we get:

[0029]

[0030] Furthermore, the step (4) includes:

[0031] For the direct link channel, we first perform matrix processing on it and rewrite the channel as:

[0032]

[0033] Among them, for the path response value f TR,l , elevation angle θ of the flow antenna port TR,l and azimuth φ TR,l ,Since the elevation and azimuth angles remain unchanged for a long time, they are measured when the flow antenna is arranged;

[0034] Assume that the port set of the flow antenna that needs to perform channel estimation is P d , the channel estimate of the direct link Written as:

[0035]

[0036] in, and represent the noise received by the dth port to be estimated in the first and second stages of pilot transmission, respectively. is the channel estimate of the d-th port; let The channel estimate can be converted into a Vandermonde matrix:

[0037]

[0038] in,

[0039] For the backscatter link channel, the same method as the direct link channel is used to convert it into a Vandermonde matrix.

[0040] Furthermore, the step (5) includes:

[0041] For a direct link channel, set the objective function:

[0042]

[0043] Then the objective function is changed to:

[0044]

[0045] Then taking the first derivative of the change we get:

[0046]

[0047] The estimated path response is then calculated as:

[0048]

[0049] in, represents the pseudo-inverse of matrix A, T represents transpose;

[0050] For the backscatter link channel, the channel estimation is achieved using the same method as the direct link channel.

[0051] Based on the same inventive concept, the present invention also provides a channel estimation system for a symbiotic communication system assisted by a flow antenna, comprising:

[0052] An initialization module is used to deploy a base station, a user, and a backscatter device for a symbiotic communication system assisted by a flow antenna. The flow antenna is installed on the base station to assist transmission. The link between the base station and the user is a direct link, and the link between the base station and the backscatter device and then to the user is a backscatter link.

[0053] The transmission module is used to implement uplink pilot transmission, including: in the first stage, the user sends a pilot signal to the base station, and at the same time, the backscatter device sends the same pilot signal to the base station; in the second stage, the user sends the pilot signal to the base station again, and the backscatter device modulates the amplitude of the signal before sending the signal to the base station;

[0054] A hybrid cancellation module is used by the base station to perform hybrid cancellation calculation processing on the signals received in the two stages;

[0055] a conversion module, used for performing matrix processing on the direct link channel and the backscatter link channel and converting them into a Vandermonde matrix;

[0056] The channel estimation module is used to perform channel estimation for the direct link and the backscatter link respectively using the least squares regression method based on the channel obtained after conversion to the Vandermonde matrix.

[0057] Based on the same inventive concept, the present invention also provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the channel estimation method for a symbiotic communication system assisted by a flow antenna according to any of the above items.

[0058] Based on the same inventive concept, the present invention also provides a computing device, comprising: one or more processors, one or more memories, and one or more programs, wherein the programs are stored in the memories and configured to be executed by the processors, and when the programs are loaded into the processors, the steps of the channel estimation method for a symbiotic communication system assisted by a flow antenna are implemented according to any one of the above items.

[0059] Based on the same inventive concept, the present invention also provides a storage medium, which stores a computer program, and the computer program includes program instructions, which, when executed by a processor, enable the processor to perform the steps of the channel estimation method for a symbiotic communication system assisted by a flow antenna according to any one of the above items.

[0060] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. The present invention can effectively eliminate inter-link interference and improve the accuracy of channel estimation by performing hybrid elimination on the pilot signal; 2. The present invention uses a low-complexity interference elimination method and a channel estimation method, and the computational complexity of the system is low; 3. The present invention is applicable to a symbiotic communication system assisted by a flow antenna with any number of users. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0062] Figure 2 Schematic diagram of the network architecture of a symbiotic communication system assisted by a fluidic antenna according to an embodiment of the present invention. DETAILED DESCRIPTION

[0063] In order to enable people in this technical field to better understand the solution of this application, the technical solution in the embodiment of this application will be clearly and completely described below in combination with the drawings in the embodiment of this application. The embodiments described in the present invention are only part of the embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0064] As attached Figure 1 As shown, the channel estimation method for the symbiotic communication system assisted by the flow antenna of this embodiment includes:

[0065] (1) A symbiotic communication system assisted by a flow antenna is configured with a base station, a user, and a backscatter device. A flow antenna is installed on the base station to assist transmission. The link from the base station to the user is a direct link, and the link from the base station to the backscatter device and then to the user is a backscatter link.

[0066] (2) Implementing uplink pilot transmission, including: in the first stage, the user sends a pilot signal to the base station, and at the same time, the backscatter device sends the same pilot signal to the base station; in the second stage, the user sends the pilot signal to the base station again, and the backscatter device modulates the amplitude of the signal and then sends the signal to the base station;

[0067] (3) The base station performs mixed elimination calculation processing on the signals received in the two stages;

[0068] (4) Matrix processing is performed on the direct link channel and the backscatter link channel, and they are converted into Vandermonde matrices;

[0069] (5) Based on the channel obtained after conversion to the Vandermonde matrix, the least squares regression method is used to estimate the channel for the direct link and the backscatter link respectively.

[0070] Specifically, in step (1), the network architecture of the symbiotic communication system assisted by the flow antenna of this embodiment is as follows: Figure 2 As shown, the scenario depicted includes one base station, one backscatter device, and one user, both of which are equipped with flow antennas. The entire system comprises: base station 201, responsible for transmitting and receiving data; backscatter device 202, which modulates and transmits received signals; user 203, which transmits signal data; and flow antenna 204, which varies its position to achieve greater diversity gain.

[0071] The channel between the base station and the user is called the direct link channel, and the channel between the base station, the backscatter device, and then the user is called the backscatter link channel. A flow antenna is installed at the base station, which can move within a certain range to build a better channel environment. Let z = [x, y] represent the local coordinates of the flow antenna carried by the base station, L Tx represents the number of flow antenna ports, Represents the corresponding matrix of the transmission field from the base station to the user, j is an imaginary number, λ is the carrier wavelength, ρ TR,l (z) = x sin θ TR,l cosφ TR,l +ycosθ TR,l represents the signal propagation distance difference of the lth port of the flow-state antenna on the direct link, θ TR,l ∈[0,π] and φ TR,l ∈[0,π] represent the elevation angle and azimuth angle of the lth port of the direct link upper stream antenna, represents the path response vector from the base station to the user. Therefore, the direct link channel can be expressed as

[0072]

[0073] Similarly, let represents the corresponding matrix of the transmission field from the base station to the backscatter device and then to the user, ρ BR,l (z) = x sin θ BR,l cosφ BR,l +ycosθ BR,l represents the signal propagation distance difference of the lth port of the upstream antenna on the backscatter link, θ BR,l ∈[0,π] and φ BR,l ∈[0,π] represent the elevation angle and azimuth angle of the lth port of the upstream antenna on the backscatter link, represents the path response vector from the base station to the backscatter device and then to the user. The backscatter link channel can be expressed as

[0074]

[0075] In step (2), the uplink pilot transmission is divided into two stages. In the first stage, the user sends a pilot signal to the base station. At the same time, the backscattering device also sends the same pilot signal to the base station. At this time, the signal received by the base station is

[0076]

[0077] Where p is the power of the signal sent by the user, is a pilot signal and satisfies α is the modulation coefficient of the backscatter device, w1 is the noise received by the base station in the first stage, which has a mean of 0 and a variance of σ 2 The normal distribution, and σ 2 is the noise power. After receiving the above signal, the base station will not perform any processing but directly go to the second stage.

[0078] In the second stage, the user sends a pilot signal to the base station again, and the backscatter device modulates the amplitude of the signal and then sends the signal to the base station. At this time, the signal received by the base station is

[0079]

[0080] Where w2 is the noise received by the base station in the first stage, which has a mean of 0 and a variance of σ 2 Normal distribution.

[0081] In step (3), with the help of the received signals of the two phases, the base station can obtain the following equations:

[0082]

[0083] Therefore, the base station can perform simple calculations to perform mixed elimination calculation processing and obtain

[0084]

[0085] Thus, the interference between the two links is eliminated. At the same time, in order to further perform channel estimation, the base station needs to transpose the pilot signal Put it on the original signal, and we get

[0086]

[0087] In step (4), since the two links are independent of each other, a similar method can be used to estimate the channel. Taking the direct link channel as an example, it is first matrixed. To this end, the channel is first rewritten as

[0088]

[0089] It can be seen that the unknowns include the path response value f TR,l and the elevation angle θ of the flow antenna port TR,l and azimuth φ TR,l ,Since the elevation and azimuth angles do not change for a long time, they can be measured when the flow antenna is previously deployed, so they can be considered as known quantities.

[0090] Assume that the port set of the flow antenna that needs to perform channel estimation is P d , with the help of the above pilot signal formula, the channel estimation of the direct link can be written as

[0091]

[0092] in and Represent the noise received by the dth port to be estimated in the first and second stages of pilot transmission respectively. The channel estimate can be converted into a Vandermonde matrix:

[0093]

[0094] in

[0095] For the backscatter link channel, the same method as the direct link channel is used to convert it into a Vandermonde matrix.

[0096] In step (5), after converting the channel estimate into a Vandermonde matrix, the least squares regression method can be used to estimate the channel for the direct link and the backscatter link respectively by minimizing the mean square error. Therefore, for the direct link channel, the objective function is first written as

[0097]

[0098] Then, change it to get

[0099]

[0100] In order to minimize the objective function, we use the first-order derivative to obtain

[0101]

[0102] After a simple change, the estimated value of the path response is

[0103]

[0104] in Represents the pseudo-inverse of matrix A.

[0105] For the backscatter link channel, the channel estimation is achieved using the same method as the direct link channel.

[0106] Based on the same inventive concept, this embodiment also provides a channel estimation system for a symbiotic communication system assisted by a flow antenna, including:

[0107] An initialization module is used to deploy a base station, a user, and a backscatter device for a symbiotic communication system assisted by a flow antenna. The flow antenna is installed on the base station to assist transmission. The link between the base station and the user is a direct link, and the link between the base station and the backscatter device and then to the user is a backscatter link.

[0108] The transmission module is used to implement uplink pilot transmission, including: in the first stage, the user sends a pilot signal to the base station, and at the same time, the backscatter device sends the same pilot signal to the base station; in the second stage, the user sends the pilot signal to the base station again, and the backscatter device modulates the amplitude of the signal before sending the signal to the base station;

[0109] A hybrid cancellation module is used by the base station to perform hybrid cancellation calculation processing on the signals received in the two stages;

[0110] a conversion module, used for performing matrix processing on the direct link channel and the backscatter link channel and converting them into a Vandermonde matrix;

[0111] The channel estimation module is used to perform channel estimation for the direct link and the backscatter link respectively using the least squares regression method based on the channel obtained after conversion to the Vandermonde matrix.

[0112] Based on the same inventive concept, this embodiment also provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the channel estimation method for a symbiotic communication system assisted by a flow antenna according to any of the above items.

[0113] Based on the same inventive concept, this embodiment also provides a computing device, including: one or more processors, one or more memories, and one or more programs, wherein the programs are stored in the memories and configured to be executed by the processors, and when the programs are loaded into the processors, the steps of the channel estimation method for a symbiotic communication system assisted by a flow antenna are implemented according to any one of the above items.

[0114] Based on the same inventive concept, this embodiment also provides a storage medium, which stores a computer program, and the computer program includes program instructions. When the program instructions are executed by the processor, the processor performs the steps of the channel estimation method for a symbiotic communication system assisted by a flow antenna according to any one of the above items.

[0115] In summary, the present invention can perform channel estimation more accurately, has lower signal processing complexity, and reduces the demand for system hardware.

[0116] The descriptions and practices disclosed in this invention are easy to understand and comprehend for those skilled in the art, and modifications and refinements may be made without departing from the principles of the invention. Therefore, modifications and improvements made without departing from the spirit of the invention should also be considered within the scope of protection of this invention.

Claims

1. A channel estimation method for a symbiotic communication system assisted by a flow antenna, characterized in that: include: (1) A symbiotic communication system assisted by a flow antenna is configured with a base station, a user, and a backscatter device. A flow antenna is installed on the base station to assist transmission. The link from the base station to the user is a direct link, and the link from the base station to the backscatter device and then to the user is a backscatter link. (2) Implementing uplink pilot transmission, including: in the first stage, the user sends a pilot signal to the base station, and at the same time, the backscatter device sends the same pilot signal to the base station; In the second stage, the user sends a pilot signal to the base station again, and the backscatter device modulates the amplitude of the signal and then sends the signal to the base station; (3) The base station performs mixed elimination calculation processing on the signals received in the two stages; (4) Matrix processing is performed on the direct link channel and the backscatter link channel, and they are converted into Vandermonde matrices; (5) Based on the channel obtained after conversion to the Vandermonde matrix, the least squares regression method is used to estimate the channel for the direct link and the backscatter link respectively.

2. The channel estimation method for a symbiotic communication system assisted by a flow antenna according to claim 1, characterized in that: The step (1) comprises: A movable flow antenna is installed at the base station end, and z = [x, y] represents the local coordinates of the flow antenna carried by the base station, L Tx represents the number of flow antenna ports, Represents the corresponding matrix of the transmission field from the base station to the user, j is an imaginary number, λ is the carrier wavelength, ρ TR,l (z) = x sin θ TR,l cosφ TR,l +ycosθ TR,l represents the signal propagation distance difference of the lth port of the flow-state antenna on the direct link, θ TR,l ∈[0,π] and φ TR,l ∈[0,π] represent the elevation angle and azimuth angle of the lth port of the direct link upper stream antenna, represents the path response vector from the base station to the user, and the direct link channel h is expressed as: make represents the corresponding matrix of the transmission field from the base station to the backscatter device and then to the user, ρ BR,l (z) = x sin θ BR,l cosφ BR,l +ycosθ BR,l represents the signal propagation distance difference of the lth port of the upstream antenna on the backscatter link, θ BR,l ∈[0,π] and φ BR,l ∈[0,π] represent the elevation angle and azimuth angle of the lth port of the upstream antenna on the backscatter link, represents the path response vector from the base station to the backscatter device and then to the user. The backscatter link channel g can be expressed as:

3. The channel estimation method for a symbiotic communication system assisted by a flow antenna according to claim 2, characterized in that: The step (2) comprises: (21) In the first stage, the user sends a pilot signal to the base station. At the same time, the backscattering device sends the same pilot signal to the base station. At this time, the first stage signal y1 received by the base station is: Where p is the power of the user's transmitted signal, h is the direct link channel, and g is the backscatter link channel. is a pilot signal and satisfies α is the modulation coefficient of the backscatter device, w1 is the noise received by the base station in the first stage, and is subject to a mean of 0 and a variance of σ 2 The normal distribution, σ 2 is the noise power; after the base station receives the signal, it does not perform any processing and directly goes to the second stage; (22) In the second stage, the user sends a pilot signal to the base station again. The backscattering device modulates the amplitude of the signal and then sends the signal to the base station. At this time, the second stage signal y2 received by the base station is Where w2 is the noise received by the base station in the first stage, which has a mean of 0 and a variance of σ 2 Normal distribution.

4. The channel estimation method for a symbiotic communication system assisted by a flow antenna according to claim 3, characterized in that: The step (3) comprises: Based on the received signals of the two phases, the base station obtains the following equations: The base station performs mixed elimination calculation processing to obtain the processed first stage signal and the processed second stage signal Then, the base station converts the pilot signal into Put it on the original signal, and we get:

5. The channel estimation method for a symbiotic communication system assisted by a flow antenna according to claim 4, characterized in that: The step (4) comprises: For the direct link channel, we first perform matrix processing on it and rewrite the channel as: Among them, for the path response value f TR,l , elevation angle θ of the flow antenna port TR,l and azimuth φ TR,l ,Since the elevation and azimuth angles remain unchanged for a long time, they are measured when the flow antenna is arranged; Assume that the port set of the flow antenna that needs to perform channel estimation is P d , the channel estimate of the direct link Written as: in, and represent the noise received by the dth port to be estimated in the first and second stages of pilot transmission, respectively. is the channel estimate of the d-th port; let The channel estimate can be converted into a Vandermonde matrix: in, For the backscatter link channel, the same method as the direct link channel is used to convert it into a Vandermonde matrix.

6. The channel estimation method for a symbiotic communication system assisted by a flow antenna according to claim 5, characterized in that: The step (5) comprises: For a direct link channel, set the objective function: Then the objective function is changed to: Then taking the first derivative of the change we get: The estimated path response is then calculated as: in, represents the pseudo-inverse of matrix A, T represents transpose; For the backscatter link channel, the channel estimation is achieved using the same method as the direct link channel.

7. A channel estimation system for a symbiotic communication system assisted by a flow antenna, characterized in that: include: An initialization module is used to deploy a base station, a user, and a backscatter device for a symbiotic communication system assisted by a flow antenna. The flow antenna is installed on the base station to assist transmission. The link between the base station and the user is a direct link, and the link between the base station and the backscatter device and then to the user is a backscatter link. The transmission module is used to implement uplink pilot transmission, including: in the first stage, the user sends a pilot signal to the base station, and at the same time, the backscatter device sends the same pilot signal to the base station; in the second stage, the user sends the pilot signal to the base station again, and the backscatter device modulates the amplitude of the signal before sending the signal to the base station; A hybrid cancellation module is used by the base station to perform hybrid cancellation calculation processing on the signals received in the two stages; a conversion module, used for performing matrix processing on the direct link channel and the backscatter link channel and converting them into a Vandermonde matrix; The channel estimation module is used to perform channel estimation for the direct link and the backscatter link respectively using the least squares regression method based on the channel obtained after conversion to the Vandermonde matrix.

8. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instruction is executed by a processor, the steps of the channel estimation method for a symbiotic communication system assisted by a flow antenna are implemented according to any one of claims 1 to 6.

9. A computing device, characterized in that include: One or more processors, one or more memories, and one or more programs, wherein the programs are stored in the memories and configured to be executed by the processors, and when the programs are loaded into the processors, the steps of the channel estimation method for a symbiotic communication system assisted by a flow antenna are implemented according to any one of claims 1 to 6.

10. A storage medium, characterized in that: The storage medium stores a computer program, which includes program instructions. When the program instructions are executed by a processor, the processor performs the steps of the channel estimation method for a symbiotic communication system assisted by a flow-state antenna according to any one of claims 1 to 6.

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