Receiver with adjustable antenna for estimating angle of arrival of an input signal - Patent Application 20070122997

Abstract

The present disclosure relates to estimating angles of arrival of one or more input signals. The present disclosure proposes a receiver and a corresponding method for operating the receiver. The receiver includes one or more antennas, where each antenna is covered with a material having controllable permittivity and / or permeability. The receiver includes a controller configured to: generate, with each antenna, a plurality of successive measurements of one or more input signals; adjust, for each antenna of the one or more antennas, a controllable material between at least two successive measurements of the plurality of successive measurements generated with the antenna; and estimate the one or more angles of arrival of the one or more input signals based on the one or more successive measurements.

Description

[Technical Field]

[0001] The present disclosure relates to angle-of-arrival (AoA) estimation of one or more input signals. The present disclosure proposes a receiver and a corresponding method for operating the receiver, where the receiver comprises one or more antennas covered by a controllable material. [Background technology]

[0002] Conventionally, measuring the AoA of a signal is performed by using an array of antennas. Conventional solutions are based on, for example, high-resolution AoA algorithms and multiple antenna techniques, for example with an array of equally spaced antennas. Most of the angle estimation techniques are based on measuring the phase difference of signals received at different antennas.

[0003] However, to avoid ambiguity between multiple sources, the number of antennas needs to exceed the number of sources of interest to be detected, resulting in many radio frequency (RF) chains being required. Therefore, conventional devices for AoA estimation can be bulky or complex for small devices. Summary of the Invention

[0004] In view of the above, the present disclosure aims to provide a smaller, more compact, and / or more efficient receiver for AoA estimation of one or more input signals.

[0005] This is achieved by the solution of the present disclosure as set forth in the independent claims. Advantageous implementations are defined in the dependent claims.

[0006] A first aspect of the present disclosure provides a receiver for estimating one or more angles of arrival of one or more input signals, respectively, the receiver comprising: one or more antennas, wherein each antenna is covered by a material having controllable permittivity and / or permeability; and a controller configured to: generate a plurality of successive measurements of the one or more input signals using each antenna of the one or more antennas to generate one or more pluralities of successive measurements; adjust, for each antenna of the one or more antennas, the controllable material between at least two successive measurements of the plurality of successive measurements generated using the antenna; and estimate the one or more angles of arrival of the one or more input signals based on the one or more pluralities of successive measurements.

[0007] The receiver of the first embodiment may be smaller, more compact, and / or more efficient than a controllable receiver because the number of antennas required for AoA estimation of one or more input signals is smaller than in a controllable receiver. The one or more input signals may be electromagnetic waves. This is achieved due to the controllable material and the adjustment of the controllable material between successive measurements.

[0008] For example, the controller may be configured to adjust the controllable material between at least two directly consecutive measurements for each of the one or more antennas. Additionally or alternatively, the controller may be configured to adjust the controllable material between every measurement of a plurality of consecutive measurements made using the antennas. Thus, every measurement made using one or more antennas may be based on a different setting of the controllable material.

[0009] The receiver may be configured to adjust, for each of the one or more antennas, the controllable material covering the antenna separately or jointly, and the controller may control the one or more antennas and the one or more controllable materials.

[0010] Each antenna of the one or more antennas may be covered by the same material having controllable permittivity and / or permeability. Alternatively, some antennas of the one or more antennas may be covered by different materials having controllable permittivity and / or permeability.

[0011] In a further implementation of the first aspect, the controller is configured to, for each antenna of the one or more antennas, adjust the refractive index of the controllable material between at least two consecutive measurements of the plurality of measurements made using the antenna.

[0012] The refractive index can be constantly adjusted to different and / or predetermined refractive indices.

[0013] In a further implementation of the first aspect, the one or more antennas are configured to form an antenna array, and / or the receiver further comprises one or more additional antennas, wherein the one or more antennas and the one or more additional antennas are configured to form an antenna array.

[0014] Each antenna in the antenna array may be equally spaced from each other.

[0015] In a further implementation of the first aspect, the controller is configured to generate each measurement of one or more of the plurality of consecutive measurements at a measurement time of the plurality of measurement times, and / or adjust the controllable material for each antenna of the one or more antennas during each measurement time of the plurality of measurement times.

[0016] In a further implementation of the first aspect, the receiver further comprises a memory, wherein for each measurement of the one or more consecutive measurements, the memory is configured to: store the measurement and store a refractive index value of the controllable material from which the measurement is generated.

[0017] The controller may be configured to measure a refractive index value of the controllable material covering each of the one or more antennas. For example, during, before, or after each of one or more consecutive measurements, the controller may measure the refractive index covering at least one of the one or more antennas to determine at least one refractive index value. The controller may measure the refractive index by controlling specialized hardware, e.g., an optical device.

[0018] Alternatively or additionally, each controllable material covering each of the one or more antennas may have one or more predetermined refractive index values.

[0019] Alternatively to refractive index values, the controller may be configured to store permittivity and / or permeability values ​​of the controllable material with which the measurements are generated.

[0020] One or more permittivity and / or permeability values ​​of each controllable material covering each of the one or more antennas may be predetermined or measured.

[0021] In a further implementation of the first aspect, the controller is configured to estimate the one or more angles of arrival of the one or more input signals based on a plurality of stored refractive index values ​​and measurements.

[0022] Each measurement of the plurality of stored measurements may correspond to one of the stored refractive index values ​​of the plurality of stored refractive index values ​​from which the measurement is generated.

[0023] Alternatively, the controller may be configured to estimate one or more angles of arrival of one or more input signals based on a plurality of stored permittivity and / or permeability values ​​and measurements.

[0024] Each measurement of the plurality of stored measurements may correspond to one of the stored permittivity and / or permeability values ​​of the plurality of stored permittivity and / or permeability values ​​from which the measurement is generated.

[0025] In a further implementation of the first aspect, each measurement of the one or more plurality of consecutive measurements comprises a phase measurement of the one or more input signals.

[0026] Each measurement of the one or more plurality of consecutive measurements may consist of a phase measurement of one or more input signals.

[0027] In a further implementation of the first aspect, the controller is configured to calculate at least one phase difference based on at least two phase measurements, or based on at least one phase measurement and a predetermined reference phase.

[0028] The predetermined reference phase may be communicated via dedicated signaling or may be estimated using a synchronization training sequence.

[0029] Each phase difference may be based on phase measurements made using the same antenna.

[0030] Alternatively, at least one phase difference may be based on phase measurements made using the same antenna, and / or one or more other phase differences may be based on phase measurements made using a different antenna, for example using a different controllable antenna.

[0031] In a further implementation of the first aspect, the controller is configured to estimate the one or more angles of arrival of the one or more input signals further based on the at least one phase difference.

[0032] In a further implementation of the first aspect, the controller is configured to estimate the one or more angles of arrival of the one or more input signals further based on the at least one phase difference and the corresponding stored refractive index value of each measurement of the one or more consecutive measurements used to calculate the at least one phase difference.

[0033] Alternatively, the controller may be configured to estimate the one or more angles of arrival of the one or more input signals further based on the at least one phase difference and the corresponding stored permittivity and / or permeability values ​​of each measurement of the one or more consecutive measurements used to calculate the at least one phase difference.

[0034] In a further implementation of the first aspect, each of the one or more plurality of consecutive measurements comprises three or more consecutive measurements, wherein the at least one phase difference has at least two phase differences, and wherein the controller is configured to: calculate, for each of the one or more input signals, a ratio of two of the at least two phase differences to form one or more phase difference ratios; and estimate the one or more angles of arrival of the one or more input signals further based on the ratio of the one or more phase differences.

[0035] In a further implementation of the first aspect, the controller is configured to calculate the two phase differences for each ratio of the one or more phase difference ratios based on at least one different phase measurement.

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[0036] In a further implementation of the first aspect, the controller is configured to estimate the one or more angles of arrival of the one or more input signals further based on a thickness of the controllable material covering each antenna of the one or more antennas and a norm of a wave vector of each of the one or more input signals.

[0037] The norm of the wave vector of each of the one or more input signals may be measured and / or may be predetermined.

[0038] In a further implementation of the first aspect, the controller is configured to estimate the one or more angles of arrival of the one or more input signals further based on a refractive index of a surrounding material.

[0039] The surrounding material may be an external medium external to the one or more antennas and the controllable material, and the refractive index of the surrounding material may be predetermined and / or estimated as an absolute value or relative to a predetermined state of the material covering the antenna.

[0040] In a further implementation of the first aspect, the controller is configured to average a plurality of measurements to form one or more averaged measurements, and to estimate the one or more angles of arrival of the one or more input signals further based on the one or more averaged measurements.

[0041] Therefore, the noise contained in the measurement can be reduced.

[0042] In a further implementation of the first aspect, the controller is configured to estimate the one or more angles of arrival of the one or more input signals further based on a predetermined lookup table comprising at least one of a differential phase and a ratio of differential phases.

[0043] The lookup table can be determined based on at least one of: the refractive index of the surrounding material, the refractive index of each controllable material for each measurement, the thickness of each controllable material, and the absolute value of the wave vector of each of the one or more input signals.

[0044] The controller may be configured to store one or more lookup tables, where each lookup table may be determined based on a different value of a corresponding parameter.

[0045] In a further implementation of the first aspect, the number of measurements of the one or more pluralities of consecutive measurements is greater than the number of the one or more input signals.

[0046] The number of measurements made using the controllable antennas combined with the number of measurements in the one or more pluralities of consecutive measurements may be greater than the number of the one or more input signals. The number of measurements in the one or more pluralities of consecutive measurements, e.g., the number of measurements of one or more antennas, may be less than the number of the one or more input signals.

[0047] In a further implementation of the first aspect, each antenna of the one or more antennas is covered with the same controllable material of the same thickness, or wherein at least two antennas of the one or more antennas are covered with at least one of different controllable materials and controllable materials of different thicknesses.

[0048] Therefore, the receiver can be simplified.

[0049] In a further implementation of the first aspect, the controller is configured to estimate the one or more angles of arrival of the one or more input signals by using at least one of a Multiple Signal Classification (MUSIC) algorithm, an estimation of signal parameters via rotational invariant techniques (ESPRIT) algorithm, and a super-resolution algorithm for uniform linear and temporal arrays (ULTA).

[0050] In a further implementation of the first aspect, the controller is configured to: generate a global matrix of steering vectors, the global matrix of steering vectors having a matrix of steering vectors for each input signal among the one or more input signals, the matrix of steering vectors having a steering vector for each measurement of the corresponding input signal; estimate the one or more angles of arrival of the one or more input signals further based on at least one of the global matrices of steering vectors; and multiply the global matrix of steering vectors by a matrix of an input signal among the one more input signals.

[0051] The phrase "each measurement," in this disclosure, may refer to each measurement of one or more consecutive measurements and / or may refer to each measurement made using one or more additional and / or controllable antennas.

[0052] One or more additional measurements made using one or more additional and / or controllable antennas may be added to one or more of the consecutive measurements, thus increasing the total number of measurements.

[0053] Each steering vector may be based on a corresponding refractive index value for each measurement of the corresponding input signal.

[0054] Alternatively, each steering vector may be based on corresponding permittivity and / or permeability values ​​for each measurement of the corresponding input signal.

[0055] The controller may be configured to estimate one or more angles of arrival of one or more input signals by using at least one of a MUSIC algorithm, an ESPRIT algorithm, and a super-resolution algorithm for ULTA based on a global matrix of steering vectors.

[0056] In a further implementation of the first aspect, the change in time of all parameters of the one or more input signals during generation of all measurements of the one or more plurality of consecutive measurements is negligible, e.g., one or more orders of magnitude smaller than the corresponding parameters of the one or more input signals.

[0057] One or more input signals may remain unchanged during the generation of one or more of the plurality of consecutive measurements.

[0058] A second aspect of the present disclosure provides a method of operating a receiver for estimating one or more angles of arrival of one or more input signals, respectively, the receiver comprising: one or more antennas, wherein each antenna is covered by a material having controllable permittivity and / or permeability; and a controller, wherein the method comprises: generating, by the controller, a plurality of successive measurements of the one or more input signals using each antenna of the one or more antennas to generate one or more plurality of successive measurements; adjusting, by the controller, for each antenna of the one or more antennas, the controllable material between at least two successive measurements of the plurality of successive measurements generated using the antenna; and estimating, by the controller, the one or more angles of arrival of the one or more input signals based on the one or more plurality of successive measurements.

[0059] The method of the second aspect may have an implementation corresponding to that of the device of the first aspect, and the method of the second aspect and its implementation achieves the advantages and benefits described above for the device of the first aspect and its respective implementation.

[0060] A third aspect of the present disclosure provides a computer program product comprising program code for performing the method of the second aspect when the program code is run on a computer.

[0061] Furthermore, in this disclosure, the phrase "controllable antenna" may refer to a controllable antenna that is not covered by a material having a controllable permittivity and / or permeability.

[0062] Furthermore, in this disclosure, the phrases "phase measurement" and "measured phase" may be used interchangeably.

[0063] Further, in the present disclosure, each measurement may comprise a phase measurement and / or each phase measurement may comprise a measurement phase.

[0064] Furthermore, in this disclosure, the phrases "controllable material" and "variable material" may be used interchangeably.

[0065] It should be noted that all devices, elements, units, and means described in this disclosure can be implemented in software or hardware elements, or any kind of combination thereof. All steps performed by various entities described in this disclosure, and functions described as being performed by various entities, are intended to mean that the respective entities are adapted or configured to perform the respective steps and functions. In the following description of specific embodiments, even if a particular function or step to be performed by an external entity is not reflected in the description of the specific detailed element of that entity that performs the particular step or function, it should be clear to those skilled in the art that these methods and functions can be implemented in the respective software or hardware elements, or any kind of combination thereof. [Brief explanation of the drawings]

[0066] The above aspects and implementations are explained in the following description of embodiments in conjunction with the accompanying drawings. [Figure 1] 1 illustrates a device according to an embodiment of the present disclosure.

[0067] [Figure 2] 1 illustrates an exemplary antenna array.

[0068] [Figure 3] 1 illustrates an antenna covered with a material having controllable permittivity and / or permeability according to an embodiment of the present disclosure.

[0069] [Figure 4] 1 shows a measurement according to an embodiment of the present disclosure.

[0070] [Figure 5a] 10 shows a graph relating differential metrics to angle of arrival according to an embodiment of the present disclosure.

[0071] [Figure 5b] 10 shows a graph of ratio of differential metrics versus angle of arrival according to an embodiment of the present disclosure.

[0072] [Figure 6] 1 shows a MUSIC spectrum based on TA according to an embodiment of the present disclosure.

[0073] [Figure 7] 1 illustrates three antennas covered with a material having controllable permittivity and / or permeability according to an embodiment of the present disclosure.

[0074] [Figure 8] 1 shows a MUSIC spectrum based on ULTA according to an embodiment of the present disclosure.

[0075] [Figure 9] 1 shows three MUSIC spectra based on ULA, TA, and ULTA according to an embodiment of the present disclosure.

[0076] [Figure 10] 1 illustrates a method according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0077] FIG. 1 illustrates a receiver 100 according to an embodiment of the present disclosure. The receiver 100 includes one or more antennas 101 and a controller 103, where each antenna 101 of the one or more antennas 101 is covered by a material 102 having controllable permittivity and / or permeability. Additionally, FIG. 1 illustrates the one or more antennas 101 receiving one or more input signals 201 at one or more angles of arrival 202. The controller 103 is configured to generate multiple successive measurements 104 of the one or more input signals using each antenna 101 of the one or more antennas 101 to generate one or more multiple successive measurements 104, where the controller 103 is configured, for each antenna 101 a of the one or more antennas 101, to adjust the controllable material 102 between at least two successive measurements of the multiple successive measurements 104 generated using the antenna 101. Additionally, the controller 103 is configured to estimate one or more angles of arrival 202 of the one or more input signals 201 based on one or more of the plurality of consecutive measurements 104 .

[0078] For example, each of the plurality of consecutive measurements 104 comprises at least two measurements made in different states of the controllable material 102 covering the antenna with which the measurements are made. Varying the state of the controllable material 102 between measurements may result in a detectable phase difference in one or more input signals 201 between the measurements.

[0079] Estimating one or more AoAs 202 using the receiver 100 may be based on an array of temporal measurements of the phase of one or more input signals 201, which may replace spatial measurements and may reduce complexity and bulkiness compared to the multi-antenna receiver 100. The spatial antenna array may be replaced with a time array. The time array may be based on generating successive measurements 104 at times of one or more input signals 201 that differ from one another. The successive measurements 104 may differ from one another due to changes in the controllable material 102 covering one or more antennas during the measurements.

[0080] The receiver 100 can reduce the complexity on the receiver (RX) side by eliminating antennas and the RF chains typically required for the antennas. An antenna array with two or more antennas can be replaced with, for example, a single adjustable antenna. Conventionally, to measure the angle of arrival, equally spaced antennas forming the antenna array are located on the RX side, and two or more phase measurements are performed to determine at least one phase difference between these antennas. The measured phase difference is used to estimate the angle of arrival of the received signal.

[0081] FIG. 2 shows an example of an array of antennas used to detect the angle of arrival 202 of a single source that generates an input signal 201 by relating the phase difference between two antenna elements to the angle of arrival 202 according to the following equation:

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[0082] In another example, many sources are emitted towards the RX side. An array of antennas having a number of antennas greater than the number of sources may be required. The received signal may be formulated as follows.

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[0083] As can be seen from Equation 2, the number of M equations (antennas) should be higher than the number of variables (sources) N. In a conventional example, M antennas and M RF chains are required to detect and measure the number of different angles of arrival N<M.

[0084] Receiver 100 permits the definition of a new type of steering vector (A) based on the time-domain measurements of one or more antennas 101. The time-domain measurements may consider a virtual array of antennas separated from each other in time rather than in space. According to Equation 2, Receiver 100 may be required to generate sufficient equations for the unknowns in Equation 2, for example, by increasing the number of consecutive measurements. The time measurements are required to be fast enough, for example, faster than the coherence time of the channel, and are performed with different settings of the controllable material 102 covering the antennas.

[0085] The same conventional algorithms (MUSIC, ESPRIT, etc.) can be applied to Receiver 100 to find the angle of arrival 202 from different sources. Receiver 100 relies on the use of a controllable material 102 located at one or more antennas 101, for example, having a controllable refractive index. At each measurement time, the refractive index can be changed to a new but known value.

[0086] A low-complexity example of a receiver 100 for estimating AoA 202 or detecting and locating a source may include only one antenna 101a. The receiver 100 may include a single antenna structure, which may enable validation. The antenna structure may include one antenna 101a and a variable dielectric material 102, such as a ferroelectric material 102 covering the antenna. The antenna structure provides the ability to vary the AoA 202 of an incident wave inside the antenna structure, generating a matrix of measurements according to Equation 2 from which the AoA 202 may be determined.

[0087] In summary, the matrix for the steering vector A in Equation 2 can be constructed from measurements performed with known angles of arrival or by using a relationship that models different conditions of the tunable material 102 covering the antenna. S can be determined from Equation 2 based on A, X, and Z. Various angle estimation techniques, e.g., super-resolution, can be applied to infer one or more angles from a series of consecutive measurements.

[0088] FIG. 3 shows a single antenna 101 a covered with a controllable material 102 receiving an input signal 201 .

[0089] In the example below of FIG. 3, the electric field of the incident plane wave is given by:

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[0090] Since the phase is relative, the differential approach uses the angle θ for single source estimation. i For estimation of AoA 202 in a multi-source scenario, super-resolution methods may be required.

[0091] If a time array of antennas is used, for example by adjusting the controllable material 102 covering one or more antennas 101 between successive measurements, the AoA 202 estimation may be based on determining the phase of the waves received by the antennas at different times corresponding to different states of the controllable material 102 covering the antennas.

[0092] FIG. 4 shows the antenna 101a and the corresponding refractive index value n t (τ i ) is an example of a continuous phase measurement generated using the phase φ(τ i ) is the time τ i refers to the phase of the signal received at the refractive index value n t (τ i ) is the time τ of the controllable material 102 covering the antenna with which the measurements are generated. i The determined phase φ(τ i ) is the signal domain

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[0093] Additionally or alternatively, the refractive index value n t (τ i ) can be combined with an averaging procedure in either the signal domain or the phase domain. t (τi ) can be predetermined or measured.

[0094] Estimation of the direction of arrival or angle of arrival 202 of one or more input signals 201 using one or more antennas 101, for example a single antenna, may be based on a phase difference approach.

[0095] Assuming one input signal 201 or a single source generating an input wave, the relationship between the angle of arrival 202 of the input signal and the phase of the wave received by the antenna is given by Equation 3. The absolute phase may not be obtainable without a reference phase, for example, communicated via dedicated signaling. Differential approaches may provide an alternative to estimating AoA 202 without requiring a reference phase and may include: - At time τ0, n t n t Set (τ0) - At time τ1, n t n t Set to (τ1) - Calculate the difference in phase of the signals observed at times τ0 and τ1, which may result in the following equation:

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[0096] Figure 5a shows the differential metric M1 = ΔΦ(t0, t1), and

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[0097] This requirement includes, for example:

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[0098] Figure 5b shows the ratio of the differential metric M2 = R(τ0, τ1, τ2), and

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[0099] FIG. 5a shows an example of a differential metric for estimating AoA 202, and FIG. 5b shows an example of a ratio of differential metrics for estimating AoA 202. sin(θ i ) 2 The term θi can be estimated based on Figure 5a or 5b, conventional estimation or function inversion techniques (zero forcing, mmse, maximum likelihood, etc.), and R(τ0, τ1, τ2) or Δφ(τ0, τ1) determined based on phase measurements.

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[0100] 5a and 5b are merely examples for specific parameters of Equations 4 and 5, e.g., different times τ i In n t (τ i ) values.

[0101] An example procedure for performing the AoA 202 estimation is as follows. - Calculate the ratio of the differential metric Δφ(τ0,τ1) or the differential metric R(τ0,τ1,τ2). - Optional noise reduction is performed by averaging multiple measurements. - Using one of the corresponding pre-calculated curves or look-up tables, for example as shown in Figure 5a or 5b, to determine the corresponding angle θ i Restore.

[0102] The MUSIC super-resolution algorithm can be used for single-source or multi-source signals. The super-resolution algorithm can be employed to recover angles of arrival 202 after a series of measurements using a temporal array (TA) antenna. Estimating one or more angles of arrival 202 can comprise: 1. Estimate an upper bound on the number of angles of arrival 202, or assume this upper bound, denoted M. 2. Compute a series of N time array measurements, each containing K refractive states, where K>M, where the nth measurement is s n (n t (τ0))…s n (n t (τ K-1 )) is shown. 3. Construct a matrix S of size K × N, where S n,k =s n (τ k ), where K>M have a common phase reference and s0…s K-1 This shall indicate the following. 4. Queue

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[0103] The approach of using time array antennas can be combined with a conventional uniform linear array of antennas. For example, Figure 7 shows an antenna array of one or more antennas 101, where each antenna 101a in the antenna array is covered with a layer of material 102 having controllable permittivity and / or permeability. In another example, only some antennas in the antenna array can be covered with a layer of material 102 having controllable permittivity and / or permeability, while other antennas in the antenna array can be controllable antennas and are not covered with material 102 having controllable permittivity and / or permeability.

[0104] All antennas of one or more antennas 101 in an antenna array may be covered by the same material 102 of the same thickness and receive the same control signal. For an array containing P elements or antennas, the super-resolution algorithms for Uniform Linear Arrays (ULA) and for Temporal Arrays (TA) are extended to include the following:

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[0105] The ULTA may be formed by two or more antennas 101 covered with a controllable material 102 forming an equidistant antenna array.

[0106] Based on the steering vector formulation according to Equation 6, the MUSIC spectrum can be calculated using conventional ULA-related algorithms. Figure 8 shows an example of a ULTA receiving two input signals 201 at 20° and 50° relative to its normal vector, where the peaks correspond to the estimated angles of arrival 202.

[0107] Figure 9 shows the advantages of time arrays and uniform linear time arrays compared to conventional uniform linear arrays. Figure 9 shows the MUSIC spectrum based on an example including five antenna elements and five input signals 201 impinging on the antenna at 20°, 40°, 50°, 60°, and 70°. The MUSIC spectrum of the ULA with five elements is unable to recover these angles of arrival 202, while the TA of a single antenna 101a with 10 time measurements recovers all angles of arrival 202. The ULTA also recovers all angles of arrival 202 and, in addition, has a narrower peak.

[0108] Therefore, AoA estimation may be more efficient and / or more accurate.

[0109] Embodiments of the present disclosure provide the following benefits: - The requirement for the number of different antennas on the RX100 side can be reduced; The requirement for the number of bulky RF chains may be reduced; Power consumption at the receiver side can be significantly reduced; Thanks to super-resolution algorithms (MUSIC, ESPRIT...) and controllable materials, multi-source detection can be performed; The complexity of channel estimation can be reduced at the RX100 side; The receiver 100 can be confined to a limited space, but is expandable to any number of sources. Combine some or all of the above.

[0110] The controller 103 may be a processor 103 .

[0111] Generally, the processor 103 may be configured to implement, execute, or initiate various operations of the receiver 100 described herein. The processor 103 may comprise hardware and / or may be controlled by software. The hardware may comprise analog circuitry or digital circuitry, or both analog and digital circuitry. The digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), digital signal processors (DSPs), or general-purpose processors. The receiver 100 may further comprise memory circuitry that stores one or more instructions that may be executed by the processor 103, e.g., under software control. For example, the memory circuitry may comprise a non-transitory storage medium that stores executable software code that, when executed by the processor 103, causes the receiver 100 to perform various operations. In one embodiment, the receiver 100 may comprise one or more processors 103 and non-transitory memory coupled to the one or more processors 103. The non-transitory memory may hold executable program code that, when executed by one or more processors 103, causes the receiver 100 to perform, execute, or initiate the operations or methods described herein.

[0112] 10 illustrates a method 300 according to an embodiment of the present disclosure. The method 300 may be performed by the receiver 100. The method 300 comprises generating 301 a plurality of successive measurements 104a of one or more input signals 201 using each antenna 101a of the one or more antennas 101 to generate one or more successive measurements 104. The method 300 further comprises adjusting 302, for each antenna 101a of the one or more antennas 101, the controllable material 202 between at least two successive measurements 104a of the plurality of successive measurements 104a generated using the antenna 101a. The method 300 further comprises 303 estimating one or more angles of arrival 202 of the one or more input signals 201 based on the one or more successive measurements 104.

[0113] The present disclosure has been described in conjunction with various embodiments as examples and implementations. However, other variations can be understood and realized by those skilled in the art and practicing the claimed subject matter, from a study of the drawings, the disclosure, and the independent claims. In the claims and the description of the invention, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in a claim. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

1. 1. A receiver for estimating one or more angles of arrival of one or more input signals respectively, the receiver comprising: one or more antennas, where each antenna is covered by a material having a controllable permittivity and / or permeability; and generating a plurality of successive measurements of the one or more input signals using each antenna of the one or more antennas to generate one or more successive measurements; For each of the one or more antennas, adjusting the controllable material between at least two consecutive measurements of the plurality of consecutive measurements made with the antenna; and estimating the one or more angles of arrival of the one or more input signals based on the one or more plurality of consecutive measurements. Controllers that are configured to A receiver comprising:

2. 2. The receiver of claim 1, wherein the controller is configured to, for each antenna of the one or more antennas, adjust the refractive index of the controllable material between at least two consecutive measurements of the plurality of consecutive measurements made with the antenna.

3. the one or more antennas are configured to form an antenna array; and / or The receiver further comprises one or more additional antennas, wherein the one or more antennas and the one or more additional antennas are configured to form an antenna array. Receiver according to claim 1 or 2.

4. The receiver further comprises a memory, wherein for each measurement of the one or more plurality of consecutive measurements, the memory stores: storing the measurements; and storing the refractive index value of said controllable material with which said measurement is generated; 3. A receiver according to claim 1 or 2, configured to:

5. 5. The receiver of claim 4, wherein the controller is configured to estimate the one or more angles of arrival of the one or more input signals based on a plurality of stored refractive index values ​​and measurements.

6. 3. The receiver of claim 1 or 2, wherein each measurement of the one or more plurality of consecutive measurements comprises a phase measurement of the one or more input signals.

7. 7. The receiver of claim 6, wherein the controller is configured to calculate at least one phase difference based on at least two phase measurements or based on at least one phase measurement and a predetermined reference phase.

8. 8. The receiver of claim 7, wherein the controller is configured to estimate the one or more angles of arrival of the one or more input signals further based on the at least one phase difference.

9. 9. The receiver of claim 8, wherein the controller is configured to estimate the one or more angles of arrival of the one or more input signals further based on the at least one phase difference and a corresponding stored refractive index value for each measurement of the one or more plurality of consecutive measurements used to calculate the at least one phase difference.

10. each plurality of consecutive measurements of the one or more consecutive measurements comprises three or more consecutive measurements; wherein the at least one phase difference includes at least two phase differences, Wherein the controller: calculating a ratio of two of the at least two phase differences to form one or more ratios of phase differences for each of the one or more input signals; and estimating the one or more angles of arrival of the one or more input signals further based on a ratio of the one or more phase differences.

8. The receiver of claim 7, configured to:

11. 11. The receiver of claim 10, wherein the controller is configured to calculate the two phase differences for each ratio of the one or more ratios of phase differences based on at least one different phase measurement.

12. 3. The receiver of claim 1, wherein the controller is configured to estimate the one or more angles of arrival of the one or more input signals further based on a thickness of the controllable material covering each antenna of the one or more antennas and a norm of a wave vector of each of the one or more input signals.

13. 3. The receiver of claim 1, wherein the controller is configured to estimate the one or more angles of arrival of the one or more input signals further based on a refractive index of a surrounding material.

14. The controller: averaging the measurements to form one or more averaged measurements; and estimating the one or more angles of arrival of the one or more input signals further based on the one or more averaged measurements.

3. A receiver according to claim 1 or 2, configured to:

15. 3. The receiver of claim 1, wherein the controller is configured to estimate the one or more angles of arrival of the one or more input signals further based on a predetermined lookup table comprising at least one of a differential phase and a ratio of differential phases.

16. 3. The receiver of claim 1 or 2, wherein the number of measurements of the one or more pluralities of consecutive measurements is greater than the number of the one or more input signals.

17. 3. The receiver of claim 1 or 2, wherein each antenna of the one or more antennas is covered with the same controllable material of the same thickness, or at least two antennas of the one or more antennas are covered with at least one of different controllable materials and controllable materials of different thicknesses.

18. 3. The receiver of claim 1, wherein the controller is configured to estimate the one or more angles of arrival of the one or more input signals by using at least one of a multiple signal classification algorithm, a signal parameter estimation via a rotation invariant technique algorithm, and a super-resolution algorithm for uniform linear and time arrays.

19. The controller: generating a global matrix of steering vectors, the global matrix of steering vectors having a matrix of steering vectors for each input signal of the one or more input signals, the matrix of steering vectors having a steering vector for each measurement of a corresponding input signal; and estimating the one or more angles of arrival of the one or more input signals further based on at least one of the global matrices of steering vectors, and multiplying the global matrices of steering vectors by an input signal matrix of the one more input signal or a matrix derived from empirical statistics of the one or more input signals.

3. A receiver according to claim 1 or 2, configured to:

20. 1. A method of operating a receiver to estimate one or more angles of arrival of one or more input signals, respectively, the receiver comprising: one or more antennas, each antenna covered by a material having a controllable permittivity and / or permeability; and a controller wherein the method comprises: generating, by the controller, a plurality of successive measurements of the one or more input signals using each antenna of the one or more antennas to generate one or more successive measurements; adjusting, by the controller, for each antenna of the one or more antennas, the controllable material between at least two consecutive measurements of the plurality of consecutive measurements made with the antenna; and estimating, by the controller, the one or more angles of arrival of the one or more input signals based on the one or more plurality of consecutive measurements. A method comprising:

21. A computer program product for causing a computer to carry out the method according to claim 20.

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