Multi-target ranging method, system, device and medium based on holographic metasurface

Abstract

The application provides a multi-target ranging method, system, device and medium based on a holographic metasurface. The method comprises establishing a receiving signal model according to the relationship between a transmitting signal of a transmitting end and a receiving signal of a receiving end. Variables of the receiving signal model include: an amplitude value of a radiation unit of the transmitting end, an amplitude value of a radiation unit of the receiving end, and a multi-target distance to be measured. A measurement precision expression of the multi-target distance to be measured is taken as an objective function. The objective function is optimized according to a constraint condition to obtain an amplitude optimization value of the radiation unit of the transmitting end and an amplitude optimization value of the radiation unit of the receiving end. The application obtains a configuration scheme of a metamaterial radiation unit in the holographic metasurface by establishing and solving an optimization problem of ranging precision, and then obtains higher ranging precision under a given power consumption limit.

Description

Technical Field

[0001] This application belongs to the field of wireless positioning technology, specifically, it relates to a multi-target ranging method, system, device and medium based on holographic metasurface. Background Technology

[0002] With the development of mobile communication systems, various positioning and sensing applications are emerging. Radar technology is one of the key technologies for positioning and sensing. Radar uses antennas to transmit and receive electromagnetic waves, and analyzes the received signals to detect and locate targets, thereby achieving positioning and sensing. However, most positioning and sensing services require limiting application power consumption. How to achieve high-precision positioning and sensing under low power consumption constraints is becoming increasingly important. Summary of the Invention

[0003] The multi-target ranging method, system, device, and medium based on holographic metasurface proposed in this invention greatly improves the ranging accuracy under given power consumption constraints.

[0004] According to a first aspect of the embodiments of this application, a multi-target ranging method based on a holographic metasurface is provided, comprising:

[0005] Based on the relationship between the transmitted signal from the transmitter and the received signal from the receiver, a received signal model is established. The variables of the received signal model include: the amplitude value of the radiating element at the transmitter, the amplitude value of the radiating element at the receiver, and the distance to be measured from multiple targets.

[0006] Based on the received signal model, the measurement accuracy expression for the distance to be measured from multiple targets is obtained;

[0007] The measurement accuracy expression of the distance to be measured from multiple targets is used as the objective function. The objective function is optimized according to the constraints to obtain the amplitude optimization value of the transmitting end radiation element and the amplitude optimization value of the receiving end radiation element.

[0008] The amplitude values ​​of the metamaterial radiation elements in the transmitter holographic metasurface are configured according to the amplitude optimization values ​​of the transmitter radiation elements, and the amplitude values ​​of the metamaterial radiation elements in the receiver holographic metasurface are configured according to the amplitude optimization values ​​of the receiver radiation elements.

[0009] After the configured transmitter transmits a signal, the configured receiver receives the reflected signals from the multiple targets under test, and obtains the distance values ​​of the multiple targets under test.

[0010] In some embodiments of this application, the measurement accuracy expression of the distance to be measured from multiple targets is used as the objective function. The objective function is optimized according to constraints to obtain the optimized amplitude values ​​of the transmitting end radiating element and the receiving end radiating element, including:

[0011] The measurement accuracy expression of the distance to be measured from multiple targets is used as the objective function, and the model is formed under the constraints of transmit power and beamforming of holographic metasurface.

[0012] The objective function is minimized by using an optimization algorithm to obtain the optimized amplitude values ​​of the transmitting and receiving radiating elements.

[0013] In some embodiments of this application, both the transmitting and receiving ends employ antennas based on reconfigurable holographic metasurfaces, and the antennas include multiple amplitude-tunable metamaterial radiating elements; establishing a received signal model specifically includes:

[0014] The formula for the effective signal r(α,t) received by the receiver is:

[0015]

[0016] The formula for the noise signal w(t) received by the receiver is:

[0017]

[0018] The signal received at the receiver is modeled as a superposition of the effective signal and the noise signal. The formula for the received signal y(t) is:

[0019]

[0020] The transmitter includes N t One radiation unit, L t One feed source; the receiver includes N r One radiation unit, L r One feed source; α refers to the vector composed of the distance parameters of the target to be measured;

[0021] Where, ψ t Refers to the beamforming matrix at the transmitting end; ψ r Refers to the beamforming matrix at the receiver; β k The reflection coefficient of the k-th target; The transmitter starts from the lth t The propagation matrix from a feed source to a metamaterial radiation unit; The receiving end starts from the lth r The propagation matrix from the feed source to the metamaterial radiation element; a t (θ k ,k) refers to the guiding vector of the transmitting end; a r (θ k (k) refers to the guide vector at the receiving end; Refers to the 1st t The signal at the feed source; f lt Refers to the 1st tThe carrier frequency of the signal at each feed point; n(t) refers to the Gaussian white noise signal received at the radiating unit of the receiver.

[0022] In some embodiments of this application, based on the received signal model, an expression for the measurement accuracy of the distance to be measured from multiple targets is obtained, including:

[0023] Based on the received signal model, the Cramérault boundary (CRB) is used to measure the accuracy of distance measurement for multiple targets; the CRB formula is:

[0024] CRB = diag{F -1};

[0025]

[0026] Where α refers to the vector composed of the distance parameters of the target to be measured; r(α,t) refers to the effective signal received by the receiver; Σ refers to the covariance matrix of the noise at the receiver; diag{·} refers to finding the diagonal vector of the matrix; Re[·] refers to taking the real part; (·) H This indicates taking the conjugate transpose.

[0027] In some embodiments of this application, the measurement accuracy expression of the distance to be measured from multiple targets is used as the objective function. The objective function is optimized according to constraints to obtain the optimized amplitude values ​​of the transmitting end radiating element and the receiving end radiating element, including:

[0028] Using the Cramer-Rao boundary (CRB) as the objective function, the model is as follows, under the constraints of transmit power and beamforming of the holographic metasurface:

[0029]

[0030]

[0031]

[0032] Where, ψ t Refers to the beamforming matrix at the transmitting end; ψ r Refers to the beamforming matrix at the receiving end; The amplitude value of the nth metamaterial radiating element at the transmitting end; The amplitude value of the nth metamaterial radiating element at the receiving end; 2 I It is the number of adjustable discrete amplitude values;

[0033] Where tr(·) represents the trace operator. M That is the maximum transmission power.

[0034] By iteratively optimizing the solution to minimize the Cramer-Rao boundary (CRB), the amplitude optimization values ​​of the transmitting and receiving radiating elements are obtained.

[0035] In some embodiments of this application, after the configured transmitter transmits a signal, the configured receiver receives the reflected signals of the multiple targets to be measured, and estimates the distance values ​​of the multiple targets to be measured, including:

[0036] The optimized received signal model is determined based on the amplitude optimization value;

[0037] Based on the reflected signals of the multiple targets to be measured, and using the optimized received signal model, the distance values ​​of the multiple targets to be measured are obtained through maximum likelihood estimation.

[0038] In some embodiments of this application, the distance values ​​of the multiple targets to be measured are obtained by maximum likelihood estimation based on the reflected signals of the multiple targets and an optimized received signal model, including:

[0039] Let α = [τ1,…,τ] K ] T , where τ k (k=1,…,) represents the time delay from the transmitted signal to the receiver after reflection from the k-th target; α is estimated using maximum likelihood estimation:

[0040]

[0041] Where L(y|α) is the log-likelihood function; according to the time delay The distances to K targets can be obtained. Right now:

[0042]

[0043] Where c refers to the speed of light.

[0044] According to a second aspect of the embodiments of this application, a multi-target ranging system is provided, which applies the multi-target ranging method of any of the above claims, specifically including:

[0045] The receiving signal model unit is used to establish a receiving signal model based on the relationship between the transmitted signal from the transmitter and the received signal from the receiver. The variables of the receiving signal model include: the amplitude value of the radiating element at the transmitter, the amplitude value of the radiating element at the receiver, and the distance to be measured from multiple targets.

[0046] The measurement accuracy expression unit is used to obtain the measurement accuracy expression for the distance to be measured from multiple targets based on the received signal model.

[0047] The optimization unit is used to take the measurement accuracy expression of the distance to be measured from multiple targets as the objective function, optimize the objective function according to the constraints, and obtain the amplitude optimization value of the transmitting end radiation unit and the amplitude optimization value of the receiving end radiation unit.

[0048] Metamaterial configuration unit: used to configure the amplitude value of the metamaterial radiation element in the transmitter holographic metasurface according to the amplitude optimization value of the transmitter radiation element, and to configure the amplitude value of the metamaterial radiation element in the receiver holographic metasurface according to the amplitude optimization value of the receiver radiation element.

[0049] The ranging unit is used to receive the reflected signals of the multiple targets under test through the configured receiver after the transmitter transmits the signal, thereby obtaining the multi-target distance values ​​of the multiple targets under test.

[0050] According to a third aspect of the embodiments of this application, a multi-target ranging device is provided, comprising:

[0051] Memory: used to store executable instructions; and

[0052] Processor: Used to connect to memory to execute executable instructions to complete the multi-target ranging method.

[0053] According to a fourth aspect of the embodiments of this application, a computer-readable storage medium is provided having a computer program stored thereon; the computer program is executed by a processor to implement a multi-target ranging method.

[0054] The multi-target ranging method, system, device, and storage medium of this application include: establishing a received signal model based on the relationship between the transmitted signal from the transmitter and the received signal from the receiver; the variables of the received signal model include the amplitude values ​​of the radiating elements at the transmitter and receiver, and the distances to be measured from the multiple targets; obtaining a measurement accuracy expression for the distances to be measured from the multiple targets based on the received signal model; using the measurement accuracy expression as the objective function, optimizing the objective function according to constraints to obtain optimized amplitude values ​​for the radiating elements at the transmitter and receiver; configuring the amplitude values ​​of the metamaterial radiating elements in the holographic metasurface at the transmitter and receiver based on the optimized amplitude values ​​of the radiating elements at the transmitter and receiver; transmitting signals from the configured transmitter and receiving the reflected signals from the multiple targets through the configured receiver to obtain the distances to be measured from the multiple targets. This application obtains the configuration scheme of the metamaterial radiating elements by establishing and solving an optimization problem of ranging accuracy, thereby achieving higher ranging accuracy under given power consumption constraints. Attached Figure Description

[0055] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0056] Figure 1 The diagram shows a reconfigurable holographic metasurface and an amplitude-tunable metamaterial radiative unit in the prior art;

[0057] Figure 2 The diagram shows a schematic representation of a radar system in an application scenario according to an embodiment of this application.

[0058] Figure 3 The diagram shows a step-by-step schematic of a multi-target ranging method according to an embodiment of this application;

[0059] Figure 4 The diagram illustrates the steps of optimizing the objective function according to an embodiment of this application;

[0060] Figure 5 The diagram shows a schematic representation of a multi-target ranging system according to an embodiment of this application.

[0061] Figure 6 The diagram shows a structural schematic of a multi-target ranging device according to an embodiment of this application. Detailed Implementation

[0062] In the process of developing this application, the inventors discovered that in the field of wireless positioning technology, existing radars often use phased arrays as antennas, and are called phased array radars. A phased array is an array composed of multiple antenna elements. The signal fed from the feed source is evenly distributed to each antenna element through a power divider. The phase shift of the signal at each antenna element can be adjusted by a phase shifter. The signals radiated by all antenna elements are superimposed to form the required waveform, thereby achieving beamforming.

[0063] A phased array radar consists of a transmitter, a receiver, and a phased array antenna. The transmitter generates the transmitted radar signal, the phased array antenna transmits and receives the radar signal, and the receiver analyzes the received signal.

[0064] The inventors discovered that by analyzing the received signal, the time delay information between it and the transmitted signal can be estimated, and the distance between the target and the radar system can be calculated, thus achieving multi-target ranging. However, due to the high power consumption of hardware components such as phase shifters and power dividers that phased array radars rely on, the ranging accuracy of phased array radars is very limited under given power consumption constraints.

[0065] To address the limited ranging accuracy of traditional radar systems under given power consumption constraints, this application proposes a multi-target ranging method based on a reconfigurable holographic metasurface to achieve higher ranging accuracy under given power consumption constraints.

[0066] The technical solution adopted in this application is based on modeling a radar system with a reconfigurable holographic metasurface, proposing a multi-target ranging method and calculating the ranging accuracy, and obtaining the configuration scheme of the reconfigurable holographic metasurface RHS by establishing and solving the optimization problem of ranging accuracy.

[0067] Figure 1 The diagram shows a schematic of a reconfigurable holographic metasurface and an amplitude-tunable metamaterial radiative unit in the prior art.

[0068] like Figure 1 As shown, a schematic diagram of the reconfigurable holographic metasurface RHS is shown. It is a leaky wave antenna that can generate the desired waveform by adjusting the radiation amplitude of the leaky wave at the metamaterial unit.

[0069] Specifically, the RHS consists of three parts: a waveguide, a feed source, and a metamaterial unit array; such as Figure 1 As shown, the radar signal is first fed into the waveguide through the feed source, and then propagates to the metamaterial unit embedded in the waveguide. Each metamaterial unit radiates the signal energy into free space in the form of a leaky wave.

[0070] The electromagnetic wave radiation amplitude at each unit can be independently controlled by adjusting the bias voltage on the unit. Specifically, each metamaterial unit is controlled by the switching states of multiple PIN diodes. Assuming a unit is controlled by I PIN diodes, then the unit has 2 I Each metamaterial element has an adjustable discrete amplitude value. By designing the amplitude value at each metamaterial element, the desired waveform can be obtained.

[0071] Figure 2 The diagram shows a schematic representation of a radar system for an application scenario according to an embodiment of this application.

[0072] like Figure 2 As shown, the application scenario of this application is a centralized RHS radar system. The RHS-based radar system includes a transmitting RHS and a receiving RHS, and both the transmitting RHS and the receiving RHS include multiple metamaterial radiating elements.

[0073] Specifically, the system includes a transmitter, a receiver, two RHSs connected to the transmitter and receiver respectively, and multiple targets at unknown distances.

[0074] The multi-target ranging method, system, device, and medium based on holographic metasurfaces as described in this application include: establishing a received signal model based on the relationship between the transmitted signal from the transmitter and the received signal from the receiver; the variables of the received signal model include the amplitude values ​​of the radiating elements at the transmitter and receiver, and the distances to be measured from the multiple targets; obtaining a measurement accuracy expression for the distances to be measured from the multiple targets based on the received signal model; using the measurement accuracy expression for the distances to be measured from the multiple targets as the objective function, optimizing the objective function according to constraints to obtain optimized amplitude values ​​for the radiating elements at the transmitter and receiver; configuring the amplitude values ​​of the metamaterial radiating elements in the holographic metasurface at the transmitter and receiver based on the optimized amplitude values ​​of the radiating elements at the transmitter and receiver; transmitting signals from the transmitter after configuration, and receiving the reflected signals from the multiple targets through the configured receiver to obtain the distances to be measured from the multiple targets.

[0075] This application obtains the configuration scheme of metamaterial radiating elements by establishing and solving the optimization problem of ranging accuracy, thereby achieving higher ranging accuracy under given power consumption constraints.

[0076] Specifically, this application can support higher radar multi-target ranging accuracy under given power consumption constraints. Due to the simple and thin hardware structure of the reconfigurable holographic metasurface, the antenna manufacturing cost can be reduced, while facilitating integrated design.

[0077] To make the technical solutions and advantages of the embodiments of this application clearer, the exemplary embodiments of this application will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0078] Example 1

[0079] Figure 3 The diagram illustrates the steps of a multi-target ranging method based on a holographic metasurface according to an embodiment of this application.

[0080] like Figure 3 As shown in the figure, the multi-target ranging method based on holographic metasurfaces in this application includes the following specific steps.

[0081] S1: Establish a receiving signal model based on the relationship between the transmitted signal from the transmitter and the received signal from the receiver. The variables in the receiving signal model include: the amplitude value of the radiating element at the transmitter, the amplitude value of the radiating element at the receiver, and the distance to be measured from multiple targets.

[0082] S2: Based on the received signal model, obtain the measurement accuracy expression for the distance to be measured from multiple targets;

[0083] S3: Using the measurement accuracy expression of the distance to be measured from multiple targets as the objective function, optimize the objective function according to the constraints to obtain the amplitude optimization value of the transmitting end radiation element and the amplitude optimization value of the receiving end radiation element;

[0084] Figure 4 The diagram illustrates the steps of optimizing the objective function according to an embodiment of this application.

[0085] Among them, such as Figure 4 As shown, S3 is further described, including: S31: Modeling the objective function using the measurement accuracy expression of the distance to be measured from multiple targets, under the constraints of transmit power and beamforming of the holographic metasurface. S32: Minimizing the objective function through an optimization algorithm to obtain the optimized amplitude values ​​of the radiating elements at the transmitting end and the receiving end.

[0086] S4: Based on the received signal model, the amplitude optimization value of the transmitting end radiation element, and the amplitude optimization value of the receiving end radiation element, the distance values ​​to be measured for multiple targets are obtained.

[0087] This application obtains the configuration scheme of metamaterial radiating elements by establishing and solving the optimization problem of ranging accuracy, thereby achieving higher ranging accuracy under given power consumption constraints.

[0088] Specifically, such as Figure 2 As shown, the RHS connected to the transmitter is called the transmitter RHS, and there are a total of N. t One radiation unit, L t There are N feed sources; the RHS connected to the receiver is called the receiver RHS, and there are a total of N. r One radiation unit, L r One feed source.

[0089] Both the transmitter and receiver employ antennas based on reconfigurable holographic metasurfaces, each antenna comprising multiple amplitude-tunable metamaterial radiating elements. The received signal model is established using the S1 step, specifically including:

[0090] The formula for the effective signal r(α,t) received by the receiver is:

[0091]

[0092] The formula for the noise signal w(t) received by the receiver is:

[0093]

[0094] The signal received at the receiver is modeled as a superposition of the effective signal and the noise signal. The formula for the received signal y(t) is:

[0095]

[0096] The transmitter includes N t One radiation unit, L t One feed source; the receiver includes N r One radiation unit, L r One feed source; α refers to the vector composed of the distance parameters of the target to be measured;

[0097] Where, ψ t Refers to the beamforming matrix at the transmitting end; ψ r Refers to the beamforming matrix at the receiver; β k The reflection coefficient of the k-th target; The transmitter starts from the lth t The propagation matrix from a feed source to a metamaterial radiation unit; The receiving end starts from the lth r The propagation matrix from the feed source to the metamaterial radiation element; a t (θ k ,k) refers to the guiding vector of the transmitting end; a r (θ k (k) refers to the guide vector at the receiving end; Refers to the 1st t The signal at each feed source; Refers to the 1st t The carrier frequency of the signal at each feed point; n(t) refers to the Gaussian white noise signal received at the radiating unit of the receiver.

[0098] Next, using step S2, based on the received signal model, the measurement accuracy expression for the distance to be measured from multiple targets is obtained, including:

[0099] Based on the received signal model, the Cramérault boundary (CRB) is used to measure the accuracy of distance measurement for multiple targets; the CRB formula is:

[0100] CRB = diag{F -1};

[0101]

[0102] Where α refers to the vector composed of the distance parameters of the target to be measured; r(α,t) refers to the effective signal received by the receiver; Σ refers to the covariance matrix of the noise at the receiver; diag{·} refers to finding the diagonal vector of the matrix; Re[·] refers to taking the real part; (·) H This indicates taking the conjugate transpose.

[0103] Furthermore, using S3, the measurement accuracy expression for the distance to be measured from multiple targets is taken as the objective function. The objective function is optimized according to the constraints to obtain the optimized amplitude values ​​of the transmitting end radiating element and the receiving end radiating element, including:

[0104] Using the Cramer-Rao boundary (CRB) as the objective function, the model is as follows, under the constraints of transmit power and beamforming of the holographic metasurface:

[0105]

[0106]

[0107]

[0108] Where, ψ t Refers to the beamforming matrix at the transmitting end; ψ r Refers to the beamforming matrix at the receiving end; The amplitude value of the nth metamaterial radiating element at the transmitting end; The amplitude value of the nth metamaterial radiating element at the receiving end; 2 I It is the number of adjustable discrete amplitude values;

[0109] Where tr(·) represents the trace operator. M That is the maximum transmission power.

[0110] By iteratively optimizing the solution to minimize the Cramer-Rao boundary (CRB), the amplitude optimization values ​​of the transmitting and receiving radiating elements are obtained.

[0111] The optimization problem in this application can be solved using various optimization algorithms, such as iterative optimization, which will not be elaborated here. By solving the above problem, the RHS radar multi-target ranging scheme can be obtained.

[0112] Next, implement step S4: configure the amplitude value of the metamaterial radiation element in the transmitter holographic metasurface according to the amplitude optimization value of the transmitter radiation element, and configure the amplitude value of the metamaterial radiation element in the receiver holographic metasurface according to the amplitude optimization value of the receiver radiation element.

[0113] This application obtains the amplitude optimization value of the metamaterial of the radiating element based on the optimization problem, and then reconfigures and optimizes the metamaterial amplitude value of the transmitter and the metamaterial amplitude value of the receiver based on the amplitude optimization value.

[0114] Finally, using S5, after the transmitter transmits the signal according to the configuration, the receiver receives the reflected signals of the multiple targets under test through the configuration, and obtains the distance values ​​of the multiple targets under test.

[0115] The specific implementation includes: first, determining the optimized received signal model based on the amplitude optimization value; then, based on the reflected signals of the multiple targets to be measured, obtaining the distance values ​​of the multiple targets to be measured through maximum likelihood estimation based on the optimized received signal model.

[0116] The specific implementation of obtaining the distance values ​​of multiple targets through maximum likelihood estimation includes the following steps:

[0117] Let α = [τ1,…,τ] K ] T , where τ k (k=1,…,) represents the time delay from the transmitted signal to the receiver after reflection from the k-th target; α is estimated using maximum likelihood estimation:

[0118]

[0119] Where L(y|α) is the log-likelihood function; according to the time delay The distances to K targets can be obtained. Right now:

[0120]

[0121] Where c refers to the speed of light.

[0122] This application can support higher radar multi-target ranging accuracy under given power consumption constraints. Due to the simple and thin hardware structure of the reconfigurable holographic metasurface, the antenna manufacturing cost can be reduced, and it is also easy to integrate the design.

[0123] In summary, the multi-target ranging method based on a holographic metasurface proposed in this application involves the following steps: S1: Establishing a received signal model based on the relationship between the transmitted signal from the transmitter and the received signal from the receiver. The variables in the received signal model include the amplitude values ​​of the radiating elements at the transmitter and receiver, as well as the distances to be measured from the multiple targets. S2: Obtaining the measurement accuracy expression for the distances to be measured from the multiple targets based on the received signal model. S3: Using the measurement accuracy expression for the distances to be measured from the multiple targets as the objective function, optimizing the objective function according to the constraints, and obtaining the optimized amplitude values ​​of the radiating elements at the transmitter and receiver. S4: Configuring the amplitude values ​​of the metamaterial radiating elements in the holographic metasurface at the transmitter and receiver based on the optimized amplitude values ​​of the radiating elements at the transmitter and receiver. S5: After the transmitter transmits the configured signal, the receiver receives the reflected signals from the multiple targets to be measured, thus obtaining the distance values ​​to be measured from the multiple targets.

[0124] This application obtains the configuration scheme of metamaterial radiating elements by establishing and solving the optimization problem of ranging accuracy, thereby achieving higher ranging accuracy under given power consumption constraints.

[0125] Example 2

[0126] This embodiment provides a multi-target ranging system that applies the multi-target ranging method of Embodiment 1. For details not disclosed in the multi-target ranging system of this embodiment, please refer to the specific implementation of the multi-target ranging methods in other embodiments.

[0127] Figure 5 The diagram shows a structural schematic of a multi-target ranging system according to an embodiment of this application.

[0128] like Figure 5 As shown, the multi-target ranging system of this application embodiment specifically includes a receiving signal model unit 10, a measurement accuracy expression unit 20, an optimization unit 30, a metamaterial configuration unit 40, and a ranging unit 50.

[0129] Specifically,

[0130] The receiving signal model unit 10 is used to establish a receiving signal model based on the relationship between the transmitted signal from the transmitter and the received signal from the receiver. The variables of the receiving signal model include: the amplitude value of the radiating element at the transmitter, the amplitude value of the radiating element at the receiver, and the distance to be measured from multiple targets.

[0131] The measurement accuracy expression unit 20 is used to obtain the measurement accuracy expression for the distance to be measured from multiple targets based on the received signal model.

[0132] The optimization unit 30 is used to take the measurement accuracy expression of the distance to be measured from multiple targets as the objective function, optimize the objective function according to the constraints, and obtain the amplitude optimization value of the transmitting end radiation element and the amplitude optimization value of the receiving end radiation element.

[0133] Specifically, optimization unit 30 includes optimization modeling unit and constraint optimization unit.

[0134] The optimization modeling unit is used to model the target distance of multiple targets as the objective function under the constraints of transmit power and beamforming of the holographic metasurface. The constraint optimization unit is used to minimize the objective function by solving the optimization algorithm to obtain the amplitude optimization values ​​of the transmitter radiation element and the receiver radiation element.

[0135] The ranging unit 40 is used to obtain the distance values ​​of multiple targets based on the received signal model, the amplitude optimization value of the transmitting end radiation unit, and the amplitude optimization value of the receiving end radiation unit.

[0136] The multi-target ranging system of this application establishes a receiving signal model by the receiving signal model unit 10 based on the relationship between the transmitted signal from the transmitter and the received signal from the receiver. The variables of the receiving signal model include: the amplitude value of the radiating element at the transmitter, the amplitude value of the radiating element at the receiver, and the distance to be measured for multiple targets. The measurement accuracy expression unit 20 obtains the measurement accuracy expression for the distance to be measured for multiple targets based on the receiving signal model. The optimization unit 30 uses the measurement accuracy expression for the distance to be measured for multiple targets as the objective function, optimizes the objective function according to the constraints, and obtains the optimized amplitude values ​​of the radiating elements at the transmitter and receiver.

[0137] The metamaterial configuration unit 40 is used to configure the amplitude value of the metamaterial radiation element in the transmitter holographic metasurface according to the amplitude optimization value of the transmitter radiation element, and to configure the amplitude value of the metamaterial radiation element in the receiver holographic metasurface according to the amplitude optimization value of the receiver radiation element.

[0138] The ranging unit 50 is used to receive the reflected signals of the multiple targets to be measured through the configured receiver after the transmitter transmits the signal, so as to obtain the distance values ​​of the multiple targets to be measured.

[0139] This application obtains the configuration scheme of metamaterial radiating elements by establishing and solving the optimization problem of ranging accuracy, thereby achieving higher ranging accuracy under given power consumption constraints.

[0140] Specifically, this application can support higher radar multi-target ranging accuracy under given power consumption constraints. Due to the simple and thin hardware structure of the reconfigurable holographic metasurface, the antenna manufacturing cost can be reduced, while facilitating integrated design.

[0141] Example 3

[0142] This embodiment provides a multi-target ranging device. For details not disclosed in this embodiment, please refer to the specific implementation details of multi-target ranging methods or systems in other embodiments. The multi-target ranging device 400 of this application embodiment includes a radar system, or is additionally connected to a radar system. The radar system includes a transmitter, a receiver, and two reconfigurable holographic metasurfaces as antennas. See [link to documentation]. Figure 2 The two antennas are connected to the transmitter and receiver, respectively.

[0143] Figure 6 The diagram shows a structural schematic of a multi-target ranging device 400 according to an embodiment of this application.

[0144] like Figure 6 As shown, the multi-target ranging device 400 includes:

[0145] Memory 402: Used to store executable instructions; and

[0146] Processor 401: Used to connect with memory 402 to execute executable instructions to complete the multi-target ranging method.

[0147] Those skilled in the art will understand that the illustration Figure 6 This is merely an example of a multi-target ranging device 400 and does not constitute a limitation on the multi-target ranging device 400. It may include more or fewer components than shown, or combine certain components, or different components. For example, the multi-target ranging device 400 may also include input / output devices, network access devices, buses, etc.

[0148] The processor 401 (Central Processing Unit, CPU) can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor, or processor 401 can be any conventional processor. Processor 401 is the control center of the multi-target ranging device 400, connecting all parts of the multi-target ranging device 400 through various interfaces and lines.

[0149] The memory 402 can be used to store computer-readable instructions. The processor 401 implements various functions of the multi-target ranging device 400 by running or executing the computer-readable instructions or modules stored in the memory 402 and calling the data stored in the memory 402. The memory 402 may mainly include a program storage area and a data storage area. The program storage area may store the operating system, application programs required for at least one function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created according to the use of the multi-target ranging device 400, etc. In addition, the memory 402 may include a hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, read-only memory (ROM), random access memory (RAM), or other non-volatile / volatile storage devices.

[0150] If the integrated modules of the multi-target ranging device 400 are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by instructing related hardware through computer-readable instructions. The computer-readable instructions can be stored in a computer-readable storage medium, and when executed by a processor, the computer-readable instructions can implement the steps of the various method embodiments described above.

[0151] Example 4

[0152] This embodiment provides a computer-readable storage medium having a computer program stored thereon; the computer program is executed by a processor to implement the multi-target ranging method in other embodiments.

[0153] The multi-target ranging device and storage medium of this application establish a received signal model based on the relationship between the transmitted signal from the transmitter and the received signal from the receiver. The variables of the received signal model include the amplitude values ​​of the radiating elements at the transmitter and receiver, and the distances to be measured from the multiple targets. Based on the received signal model, a measurement accuracy expression for the distances to be measured from the multiple targets is obtained. Using this expression as the objective function, the objective function is optimized according to constraints to obtain optimized amplitude values ​​for the radiating elements at both the transmitter and receiver. The amplitude values ​​of the metamaterial radiating elements in the holographic metasurface at the transmitter and receiver are configured based on these optimized amplitude values. After the transmitter transmits the configured signal, the receiver receives the reflected signals from the multiple targets to be measured, thus obtaining the distance values ​​to be measured from the multiple targets. This application obtains a configuration scheme for the metamaterial radiating elements by establishing and solving an optimization problem for ranging accuracy, thereby achieving higher ranging accuracy under given power consumption constraints.

[0154] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0155] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0156] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0157] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0158] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms “a,” “the,” and “the” used in this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0159] It should be understood that although the terms first, second, third, etc., may be used in this invention to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first information may also be referred to as second information without departing from the scope of this invention, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0160] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0161] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A multi-target ranging method based on a holographic metasurface, characterized in that, include: A receiving signal model is established based on the relationship between the transmitted signal at the transmitter and the received signal at the receiver. The variables in the received signal model include: the amplitude value of the transmitting end radiating element, the amplitude value of the receiving end radiating element, and the distance to be measured from multiple targets. Based on the received signal model, the measurement accuracy expression for the distance to be measured from multiple targets is obtained; The measurement accuracy expression of the distance to be measured from the multi-target target is used as the objective function. The objective function is optimized according to the constraints to obtain the amplitude optimization value of the transmitting end radiation element and the amplitude optimization value of the receiving end radiation element. The amplitude values ​​of the metamaterial radiation units in the transmitter holographic metasurface are configured according to the amplitude optimization values ​​of the transmitter radiation units, and the amplitude values ​​of the metamaterial radiation units in the receiver holographic metasurface are configured according to the amplitude optimization values ​​of the receiver radiation units. After the configured transmitter transmits the signal, the configured receiver receives the reflected signals of the multiple targets to be measured, and the distance values ​​of the multiple targets to be measured are estimated. Both the transmitting and receiving ends employ antennas based on reconfigurable holographic metasurfaces, and the antennas include multiple amplitude-tunable metamaterial radiating elements; the establishment of the received signal model specifically includes: Valid signal received by the receiver The formula is: ； Formula for noise signal received by the receiver for: ； The received signal is modeled as a superposition of a valid signal and a noise signal. The formula is: ； The transmitting end includes One radiation unit A feed source; the receiver includes One radiation unit One feed source; 'Refers to the vector composed of distance parameters of the target to be measured; in, ; Refers to the beamforming matrix at the receiving end; Refers to the first The reflection coefficient of the target; The transmitter starts from the first The propagation matrix from a feed source to a metamaterial radiation unit; The receiving end starts from the first The propagation matrix from a feed source to a metamaterial radiation unit; Refers to the guiding vector at the transmitting end; Refers to the steering vector at the receiving end; Refers to the first The signal at each feed source; Refers to the first The carrier frequency of the signal at each feed source; The Gaussian white noise signal received at the radiating element of the receiving end. Indicates that the transmitted signal passes through the first The time delay from the reflection of a target to the receiving end.

2. The multi-target ranging method according to claim 1, characterized in that, The step of using the measurement accuracy expression of the multi-target distance to be measured as the objective function, and optimizing the objective function according to the constraints to obtain the amplitude optimization value of the transmitting end radiation element and the amplitude optimization value of the receiving end radiation element includes: The measurement accuracy expression of the multi-target distance to be measured is used as the objective function, and modeling is performed under the constraints of transmission power and beamforming of holographic metasurface; The objective function is minimized by solving an optimization algorithm to obtain the amplitude optimization values ​​of the transmitting end radiation element and the receiving end radiation element.

3. The multi-target ranging method according to claim 1, characterized in that, The step of obtaining the measurement accuracy expression for the distance to be measured from multiple targets based on the received signal model includes: Based on the received signal model, the Cramérault boundary (CRB) is used to measure the measurement accuracy of the distance to the multiple targets; the CRB formula is: ； ； in, 'Refers to the vector composed of distance parameters of the target to be measured; Σ refers to the effective signal received at the receiver; Σ refers to the covariance matrix of the noise at the receiver. This refers to finding the diagonal vector of a matrix; Take the real part, This indicates taking the conjugate transpose.

4. The multi-target ranging method according to claim 3, characterized in that, The step of using the measurement accuracy expression of the multi-target distance to be measured as the objective function, and optimizing the objective function according to the constraints to obtain the amplitude optimization value of the transmitting end radiation element and the amplitude optimization value of the receiving end radiation element includes: Using the Cramer-Rao boundary (CRB) as the objective function, the model is as follows, under the constraints of transmit power and beamforming of the holographic metasurface: ； ； ； in, ; Refers to the beamforming matrix at the receiving end; The first term of the transmitting end The amplitude value of each metamaterial radiation unit; The first one refers to the receiving end The amplitude value of each metamaterial radiation unit; It is the number of adjustable discrete amplitude values; in, This represents the trace operator. That is the maximum transmission power; By iteratively optimizing the solution to minimize the Cramer-Rao boundary (CRB), the amplitude optimization values ​​of the transmitting and receiving radiating elements are obtained.

5. The multi-target ranging method according to claim 4, characterized in that, After the configured transmitter transmits a signal, the configured receiver receives the reflected signals from the multiple targets under test. The multi-target distance values ​​are then estimated, including: The optimized received signal model is determined based on the amplitude optimization value; Based on the reflected signals of the multiple targets to be measured, and using the optimized received signal model, the distance values ​​of the multiple targets to be measured are obtained through maximum likelihood estimation.

6. The multi-target ranging method according to claim 5, characterized in that, Based on the reflected signals of the multiple targets to be measured, and using the optimized received signal model, the distance values ​​of the multiple targets to be measured are obtained through maximum likelihood estimation, including: set up ,in Indicates that the transmitted signal passes through the first The time delay from the target reflection to the receiver is estimated using maximum likelihood estimation. : ； in, Log-likelihood function; based on time delay It can be obtained Distance to each target ,Right now: ； Where c refers to the speed of light.

7. A multi-target ranging system, employing the multi-target ranging method of any one of claims 1-5, characterized in that, Specifically, it includes: The received signal model unit is used to establish a received signal model based on the relationship between the transmitted signal at the transmitter and the received signal at the receiver. The variables in the received signal model include: the amplitude value of the transmitting end radiating element, the amplitude value of the receiving end radiating element, and the distance to be measured from multiple targets. The measurement accuracy expression unit is used to obtain the measurement accuracy expression for the distance to be measured from multiple targets based on the received signal model. An optimization unit is used to take the measurement accuracy expression of the distance to be measured from the multi-target as the objective function, optimize the objective function according to the constraints, and obtain the amplitude optimization value of the transmitting end radiation unit and the amplitude optimization value of the receiving end radiation unit. Metamaterial configuration unit: configured to configure the amplitude value of the metamaterial radiation unit in the transmitter holographic metasurface according to the amplitude optimization value of the transmitter radiation unit, and to configure the amplitude value of the metamaterial radiation unit in the receiver holographic metasurface according to the amplitude optimization value of the receiver radiation unit; The ranging unit is used to receive the reflected signals of the multiple targets under test through the configured receiver after the transmitter transmits the signal, and to estimate the distance values ​​of the multiple targets under test.

8. A multi-target ranging device, comprising: Memory: Used to store executable instructions; as well as Processor: For connection to memory to execute executable instructions to perform the multi-target ranging method as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, It stores a computer program; the computer program is executed by a processor to implement the multi-target ranging method as described in any one of claims 1-6.

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