Method for measuring angle of arrival with phased array

Abstract

This invention relates to a method for measuring the angle of arrival (AoA) using a steerable phased array. The method includes, but is not limited to: receiving a signal through a steerable phased array having a first steering angle and a second steering angle; obtaining a first power-related information (PRI1) of the signal corresponding to the first steering angle; obtaining a second power-related information (PRI2) of the signal corresponding to the second steering angle; and calculating the angle of arrival of the signal based on the first power-related information and the second power-related information, wherein the first steering angle is different from the second steering angle, and the absolute difference between the first steering angle and the second steering angle is less than a first null beamwidth / 2.

Description

Technical Field

[0001] This invention relates to phased arrays, and more specifically, to a method for rapidly measuring the angle of arrival (AoA) using a steerable phased array. Background Technology

[0002] In modern long-distance communication systems, carrier frequencies are becoming increasingly higher to allow for wider signal bandwidth. According to Frii's transmission equation, the signal transmitted by the receiver (P...)... r The power received is the same as that of the transmitter (P). t The ratio between the transmitted powers is expressed as:

[0003]

[0004] In equation (1), D t and D r These refer to the directivity of the transmitter's antenna and the receiver's antenna, respectively. It is evident that the carrier's wavelength decreases as its frequency increases, and therefore signal attenuation or decay becomes worse due to the ratio P. r / P t It decreases as the wavelength λ decreases. To compensate for path loss, the conventional and obvious solution is to increase the antenna's directivity D. t and directionality D r Any one or two of them.

[0005] However, as directivity increases, the beamwidth, typically expressed as half-power beamwidth (HPBW), decreases. Therefore, when the transmitter and receiver are moving, they are easily lost from each other. Beam tracking technology is a widely researched area. Although some algorithms based on the extended Kalman filter (EKF) have been proposed in existing technologies, the accuracy and precision of AoA measurements still affect the prediction results. Therefore, a real-time method for measuring the AoA of a beam is needed. Summary of the Invention

[0006] Therefore, the present invention provides a method for measuring the angle of arrival (AoA) of a beam. The provided method can be operated in real-time applications.

[0007] In one exemplary embodiment, the present invention relates to a method for measuring the angle of arrival (AoA) using a steerable phased array. The method includes, but is not limited to: receiving signals through a steerable phased array having a first steering angle and a second steering angle; obtaining first power-related information (PRI1) corresponding to the signal at the first steering angle; obtaining second power-related information (PRI2) corresponding to the signal at the second steering angle; and calculating the AoA of the signal based on the first power-related information and the second power-related information, wherein the first steering angle is different from the second steering angle, and the absolute difference between the first steering angle and the second steering angle is less than FNBW / 2.

[0008] In one exemplary embodiment, the present invention relates to a communication device. The communication device includes, but is not limited to, a transceiver, a storage medium, and a processor. The transceiver includes, but is not limited to, a steerable phased array. The processor is coupled to the transceiver and the storage medium. The processor is configured to: receive a signal via a steerable phased array having a first steer angle and a second steer angle; obtain a first power-related information (PRI1) of the signal corresponding to the first steer angle; obtain a second power-related information (PRI2) of the signal corresponding to the second steer angle; and calculate the AoA of the signal based on the first power-related information and the second power-related information, wherein the first steer angle is different from the second steer angle, and the absolute difference between the first steer angle and the second steer angle is less than FNBW / 2.

[0009] However, it should be understood that the content of this invention may not encompass all aspects and embodiments of the invention, and therefore is not intended to limit or constrain it in any way. Furthermore, this invention includes improvements and modifications that will be obvious to those skilled in the art. Attached Figure Description

[0010] The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the embodiments, serve to explain the principles of the invention.

[0011] Figure 1 This is a schematic diagram of the beam radiation pattern of a phased array according to an embodiment of the present invention.

[0012] Figure 2 This is a flowchart of a method for measuring the angle of arrival according to an embodiment of the present invention.

[0013] Figure 3 This is a flowchart illustrating the updated angle of arrival according to an embodiment of the present invention.

[0014] Figure 4AThis is a schematic diagram of the HPBW and the main lobe points used to approximate the beam radiation pattern according to an embodiment of the present invention.

[0015] Figure 4B This is a schematic diagram of the parabolic approximation of the main lobe of the beam radiation pattern according to an embodiment of the present invention.

[0016] Figure 5 This is a schematic diagram illustrating the switching of steering angle to calculate AoA according to an embodiment of the present invention.

[0017] Figures 6A to 6C This is a schematic diagram illustrating the beam radiation field pattern for understanding when the actual AoA is 12°, according to an embodiment of the present invention.

[0018] Figure 7A and Figure 7B A schematic diagram illustrating an example of the proposed method according to an embodiment of the present invention providing convergence results for fast tracking.

[0019] Figure 8 This is a schematic diagram of a phased array using an analog beamforming architecture according to an embodiment of the present invention.

[0020] Figure 9 This is a schematic diagram of a phased array using a digital beamforming architecture according to an embodiment of the present invention.

[0021] Figure 10 This is a block diagram of a communication device according to an embodiment of the present invention.

[0022] Figure 11A This is a schematic diagram of a communication system with base station scanning user equipment according to an embodiment of the present invention.

[0023] Figure 11B This is a schematic diagram of a communication system with a user equipment scanning base station according to an embodiment of the present invention.

[0024] Figure 11C This is a schematic diagram of a communication system in which a base station and a user equipment scan each other, according to an embodiment of the present invention.

[0025] Figure 12 This is a schematic diagram of a two-dimensional phased array according to an embodiment of the present invention.

[0026] Explanation of icon numbers

[0027] 40, 71, 72, 73: Main lobe;

[0028] 80, 90: Phased array;

[0029] 81, 91: Digital processors;

[0030] 82, 92: AD / DA converters;

[0031] 83: Aggregator;

[0032] 100: Communication device;

[0033] 110: Transceiver;

[0034] 120: Processor;

[0035] 130: Storage media;

[0036] 401, 402: Half-power points;

[0037] 601, 602, 611, 612, 621, 622, 701, 702, 703, hp1, hp2: points;

[0038] 403: Vertex;

[0039] 1101a, 1101b, 1102a, 1102b: Beams;

[0040] AMP: Amplifier;

[0041] ANT: Antenna element;

[0042] AP: Array Plane;

[0043] GCA: Gain-Controllable Amplifier;

[0044] L: Vertical line;

[0045] L1, L2: Dashed lines;

[0046] MX: Mixer;

[0047] PHS: Phase Shifter;

[0048] S201, S203, S205, S207, S302, S304, S306: Steps;

[0049] STA: Base Station;

[0050] UE: User Equipment;

[0051] x, y, z: axes;

[0052] Δθ1, Δθ2: difference angles;

[0053] θ S1 First steering angle;

[0054] θ S2 Second steering angle. Detailed Implementation

[0055] To enable the foregoing features and advantages of the invention to be understood, exemplary embodiments with accompanying drawings are described in detail below. It should be understood that both the foregoing general description and the following detailed description are exemplary and intended to provide further explanation of the invention as claimed.

[0056] Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used in the drawings and descriptions to refer to the same or similar parts.

[0057] Figure 1 This is a schematic diagram of the beam radiation pattern of a phased array according to an embodiment of the present invention. See also... Figure 1 A phased array's beam pattern can contain a main lobe and several side lobes. The main lobe is the main beam of the phased array, where the maximum and constant energy is radiated through the phased array. The beamwidth is the range within the main lobe of the beam pattern that radiates most of the power. In practice, beamwidth is usually expressed as half-power beamwidth (HPBW) or first null beamwidth (FNBW).

[0058] HPBW is defined as the angular distance between points in the beam radiation pattern where the power decreases by 50% (or -3dB) from the peak value of the main beam. For example... Figure 1 As shown, a line is drawn between the two half-power points on the main lobes on both sides. The angle between the half-power points is the HPBW of the beam radiation pattern.

[0059] FNBW is defined as the angular distance between the first null points, where the magnitude of the beam radiation pattern is zero near the main lobe. For example... Figure 1 As shown, a line is drawn between the two first nulls on the main lobes on both sides. The angle between the first nulls is the FNBW of the beam radiation pattern. From Figure 1 It can be seen that HPBW is smaller than FNBW.

[0060] Phased arrays can switch between steering angles to measure the angle of arrival. Different steering angles result in different beam radiation patterns. Therefore, HPBW or FNBW can change with different steering angles.

[0061] Uniformly linear phased arrays (ULA) are the most commonly used type of phased array. They have θ... S The half-power beamwidth of a uniform linear phased array of N antenna elements with a steering angle can be expressed as:

[0062]

[0063] Here, d refers to the distance between the centroids of two adjacent antenna elements, and λ refers to the wavelength of the electromagnetic waves emitted and / or received by the antenna elements.

[0064] For example, consider a phased array with four antenna elements (N=4), where the spacing (d=λ / 2) is half the wavelength and the steering angle is zero degrees (θ). S =0), HPBW is approximately 25.4 degrees. If the information signal originates from a direction close to the steering angle, then when the steering angle changes by approximately 5 degrees, the received power of the information signal will not change much, and therefore the communication quality remains acceptable. Over a short time span, the absolute difference between steering angles is small, and it can be assumed that the change in received power at different steering angles is negligible, such that the main lobe of the beam pattern can be approximated by a parabolic curve associated with the difference angle and HPBW. Therefore, assuming the absolute difference between steering angles is limited by a threshold, the angle of arrival can be evaluated by the steering angle and its corresponding power-related information (PRI). In one embodiment, the threshold can be associated with the FNBW and / or HPBW of the main lobe of the beam pattern.

[0065] Figure 2 This is a flowchart of a method for measuring the angle of arrival according to an embodiment of the present invention. The method may be adapted to a phased array. In step S201, the phased array receives signals having a first steering angle and a second steering angle. In step S203, the phased array obtains a first power-related information (PRI1) corresponding to the signal with the first steering angle. In step S205, the phased array obtains a second power-related information (PRI2) corresponding to the signal with the second steering angle. In step S207, the phased array calculates the AoA of the signal based on the first power-related information and the second power-related information.

[0066] It should be noted that the first steering angle is different from the second steering angle, and the absolute difference between the first steering angle and the second steering angle is less than the threshold.

[0067] Steps S201 and S203 do not significantly or adversely affect signal transmission. Therefore, the method can be used in real-time applications, i.e., situations where signal transmission or reception involves telecommunications.

[0068] In one embodiment, the absolute difference between the first steering angle and the second steering angle is less than FNBW / 2.

[0069] In one embodiment, the absolute difference between the first steering angle and the second steering angle is less than HPBW / 2.

[0070] In one embodiment, the absolute difference between the first steering angle and the second steering angle is less than HPBW / 4.

[0071] Figure 3 This is a flowchart illustrating the updated angle of arrival according to an embodiment of the present invention. Figure 3 The steps in can be regarded as Figure 2 A variation of step S207 in [the document / document]. Please see [the document / document / document]. Figure 3 In step S302, the phased array treats the calculated AoA as a third steering angle to receive the signal. Specifically, the calculated AoA may be the result calculated from step S207. The calculated AoA may also be an evaluation of the current AoA obtained through a prediction mechanism such as Kalman filtering. In step S304, the phased array obtains third power-related information (PRI3) of the signal corresponding to the third steering angle. In step S306, the phased array updates the AoA based on the third power-related information and the third steering angle.

[0072] In one embodiment, the first power-related information and the second power-related information may include, but are not limited to, a metric representation of at least one of received power, signal-to-noise ratio (SNR), error vector magnitude (EVM), bit error rate (BER), and carrier-to-noise ratio (C / N). Similarly, the third power-related information may include, but is not limited to, a metric representation of at least one of received power, signal-to-noise ratio (SNR), error vector magnitude (EVM), bit error rate (BER), and carrier-to-noise ratio (C / N).

[0073] As an example, the first and second power-related information can be the carrier-to-noise ratio (C / N). The focus now is on obtaining the C / N1 of the signal corresponding to the first steering angle and the C / N2 of the signal corresponding to the second steering angle. E can be calculated from the bit error rate (BER). b / N0, the relationship varies with the modulation and coding scheme. Next, E is obtained based on the following equation. b Use / N0 to calculate C / N:

[0074]

[0075] Here, f b B refers to the net bit rate or data rate of the channel, and B refers to the channel bandwidth. Both are predetermined or available. Therefore, C / N can be calculated based on BER, and C / N1 and C / N2 are now obtained from the BER of the data relative to the first segment of the information signal corresponding to the first steering angle and the BER of the data relative to the second segment of the information signal corresponding to the second steering angle.

[0076] [Parabolic Approximation]

[0077] The simplified mechanism for calculating the angle of arrival (AoA) based on the obtained C / N1 and C / N2 is a parabolic approximation of the shape of the main lobe of the phased array. Ideally, the field pattern of the amplitude associated with a uniform linear phased array with N antenna elements can be expressed as:

[0078] G A (θ)=AF(θ,θ S )×EF(θ) (4)

[0079] Here, G A The amplitude gain of the phased array is referred to as AF, the array factor as AF, and the element factor as EF, which is also called the field pattern of the antenna element. In one embodiment, the phased array first switches to a first steering angle θ. S1 To receive signals from the signal source. The phased array then switches to the second steering angle θ in both digital and analog modes. S2 To receive the same signal from the signal source. The ratio between the power received at the first steering angle and the power received at the second steering angle is expressed as:

[0080] P r1,dB -P r2,dB =AF(AoA,θ S1 ) dB -AF(AoA,θ S2 ) dB (5)

[0081] Therefore, the effect of the unit factor is eliminated. When the ratio of the received power and the array factor AF in the model is known, the angle of arrival AoA can then be derived. The array factor AF can be expressed as:

[0082]

[0083]

[0084] However, several obstacles exist that render equations (6-1) and / or (6-2) inapplicable. The first problem is that these equations are transcendental functions, and their logarithmic values ​​(dB) are difficult to obtain. Another problem is that these equations are theoretically only suitable for uniform linear phased arrays (ULAs), while most phased arrays in use are not perfect ULAs, and their actual radiation patterns are far more complex than equations (6-1) and / or (6-2). Therefore, a simplifying method is introduced in this invention. It is known that any higher-order function or any transcendental function can be approximated or approximated by a second-order polynomial / parabolic function.

[0085] Figure 4AThis is a schematic diagram of the HPBW and points of the main lobe for approximating the beam radiation pattern according to an embodiment of the present invention. See also... Figure 4A The shape of the main lobe 40 of the beam radiation pattern can be approximated by a parabolic curve defined by half-power points 401, 402, and vertex 403. Half-power points 401 and 402 correspond to points with half-received power P. AF / 2 of the two steering angles, and vertex 403 corresponds to the peak power P AF The turning angle. Therefore, the parabolic curve is determined by the power and turning angle of three points, 401, 402, and 403, to fit the shape of the main lobe 40.

[0086] Based on the above assumptions and equation (2), it can be approximated as:

[0087]

[0088] Here, Δθ refers to the difference angle between the selected angle and the turning angle. In equation (7), λ is the wavelength of the carrier signal in the first medium in which the antenna array is located. In conventional examples, the wavelength is the wavelength of the carrier signal in free space or air. However, the method of the present invention is still applicable even if the antenna array is located on the seabed.

[0089] Consider a one-dimensional array with four antenna elements as an example. If the spacing d between two adjacent antenna elements is equal to half the operating wavelength, then equation (7) yields the following result:

[0090]

[0091]

[0092] For the aforementioned example, P AF、dB The array factor is represented by a decibel value. If the difference angle Δθ does not exceed 5 degrees, then the difference is much less than 1. Therefore, according to the first-order Taylor series of the natural logarithm function, the equation (9) can be approximated as the following equation (10):

[0093] P AF,dB (Δθ,θ S )≈k(Δθcosθ S ) 2 (Δθ and θ) S (in degrees) (10)

[0094] Generally, k is a coefficient associated with the number of antenna elements N, the spacing d between two adjacent antenna elements, and the wavelength λ. In one embodiment, for a phased array with four antenna elements (N=4) and a spacing d=λ / 2, the coefficient k in equation (10) is k=-0.0135.

[0095] Figure 4B This is a schematic diagram of the parabolic approximation of the main lobe of the array factor of the beam radiation pattern according to an embodiment of the present invention. Figure 4B The diagram illustrates a real model of a phased array with four antenna elements (N=4), the sinc function approximation, and the parabolic approximation of the array factor. The real model is the shape of the main lobe as described by equation (6-1). The sinc function approximation corresponds to the shape of the main lobe as described by equation (6-2). The parabolic approximation corresponds to the shape of the main lobe as described by equation (7).

[0096] At angle θ = 0 degrees, the Singer function approximation and the parabolic approximation fit the peak power points on the main lobe of the real model. Points hp1 and hp2 are the approximate half-power points according to the parabolic approximation. It is worth noting that the parabolic approximation matches the Singer function approximation at points hp1 and hp2, and points hp1 and hp2 are close to the left and right half-power points as characterized by the real model. Therefore, especially when the difference angle Δθ is small, the parabolic approximation by equation (7) will provide a good approximation of the real model. For example, in an embodiment with four antenna elements and a spacing of half the wavelength, the difference angle Δθ is set to less than 5 degrees, which is much smaller than half of its theoretical HPBW.

[0097] Figure 5 This is a schematic diagram illustrating the switching of steering angles to calculate AoA according to an embodiment of the present invention. Please refer to... Figure 5 The vertical line L is a reference line orthogonal to the array plane AP of the phased array. The phased array can be turned to a first turning angle θ corresponding to the dashed line L1. S1 The received signal. Then, the phased array can be turned to the second turning angle θ corresponding to the dashed line L2. S2 The received signal. This corresponds to, for example... Figure 2 Step S201 as described herein. Note that the first steering angle θ S1 Second steering angle θ S2 Different. Now, to measure the angle of arrival (AoA) of the incoming signal, the selected angle is replaced with AoA, and the antenna array is turned at the first example to a first turning angle θ calculated or predicted by some algorithm around AoA. S1 The values ​​of the difference angles Δθ1 and Δθ2 are represented as AoA and the first steering angle θ, respectively. S1 Second steering angle θS2 The difference between them.

[0098] Next, the received power can be expressed as:

[0099] G RX,dB (AoA,θ S1 ) = P AF,dB (AoA-θ S1 ,θ S2 )+P EF,dB (AoA) (11)

[0100] Assuming the signal power itself remains constant, the antenna array then switches its steering angle to a second steering angle θ. S2 And the received power can be expressed as:

[0101] G RX,dB (AoA,θ S2 ) = P AF,dB (AoA-θ S2 ,θ S2 )+P EF,dB (AoA) (12)

[0102] G RX,dB (AoA,θ S2 ) and G RX,dB (AoA,θ S1 The difference between the two (in dB) is equal to the power ratio, which can be written as:

[0103] ΔG RX,dB (AoA,θ S1 ,θ S2 ) = P AF,dB (AoA-θ S2 ,θ S2 )-P AF,dB (AoA-θ S1 ,θ S1 (13)

[0104] According to equation (10), equation (13) can be rewritten as:

[0105] ΔG RX,dB (AoA,θ S1 ,θ S2 )=k(Δθ2cosθ S2 ) 2 -k(Δθ1cosθ S1 ) 2 (14)

[0106] In equations (13) to (14), ΔG RX,dB (AoA,θ S1 ,θS2 ) is at the second steering angle θ S2 Power P received at the location AF,dB (AoA-θ S2 ,θ S2 ) and at the first steering angle θ S1 Power P received at the location AF,dB (AoA-θ S1 ,θ S1 The decibel value of the ratio of ) to ).

[0107] Figures 6A to 6C This is a schematic diagram illustrating the beam radiation field pattern for understanding when the actual AoA is 12°, according to an embodiment of the present invention.

[0108] Please refer to Figures 6A to 6C . Figures 6A to 6C Each image depicts the actual radiation pattern of an antenna array with four antenna elements spaced half the wavelength. The right / upward axis and direction represent positive, and the left / downward axis and direction represent negative. Figures 6A to 6C In this context, AoA is 12°. Figure 6A In the middle, the first steering angle θ S1 The second steering angle is 10° and θ S2 The first steering angle is 15°. The first steering angle corresponds to point 601 on the main lobe. At point 601, the received power (in dB) is -0.5265 dB. The second steering angle corresponds to point 602 on the main lobe. At point 602, the received power (in dB) is -0.5930 dB. From... Figure 6A In the example, the difference in power received between point 601 and point 602 (in dB) is -0.0665 dB.

[0109] In the previous assumptions, it is known that:

[0110] Δθ1-Δθ2=Δθ S =θ S2 -θ S1 (15)

[0111]

[0112] a = cos 2 θ S1 -cos 2 θ S2 (17)

[0113] b=2Δθ S cos 2 θ S2 (18)

[0114]

[0115] In one embodiment, the value of m is calculated as follows:

[0116]

[0117] In equation (20), N is the number of antenna elements, d is the distance between two adjacent antenna elements, and λ is the wavelength of the signal. Here, the denominator "296" on the right side of equation (20) is a local optimum. In other embodiments, the value of the denominator may be slightly different from "296". Due to the difference angle Δθ S The difference will affect the approximation error, therefore the range of the denominator can vary with the difference angle Δθ. S Change.

[0118] With equations (15) and (19) replacing all known variables, the calculated first difference angle Δθ1 is 1.9577°. Therefore, the calculated AoA is obtained from the first turning angle and the first difference angle as θ. S1 +Δθ1 = 11.9577°. That is to say, when the actual AoA is between the two steering angles, the calculated AoA is very close to the actual AoA.

[0119] exist Figure 6B In the middle, the first steering angle θ S1 The second steering angle is 10° and θ S2 The first steering angle is 5°. The first steering angle corresponds to point 611 on the main lobe. At point 611, the received power (in dB) is -1.1648 dB. The second steering angle corresponds to point 612 on the main lobe. At point 612, the received power (in dB) is -0.5266 dB. From... Figure 6B In the above, the difference in power received between points 611 and 612 (in dB) is -0.6382 dB. With equations (15) to (20) replacing all known variables, the calculated first difference angle Δθ1 is 2.2474°, therefore the calculated AoA is θ. S1 +Δθ1 = 12.2474°. In this example, even though the second steering angle moves away from the actual AoA when compared with the first steering angle, the calculated AoA is still very close to the actual AoA.

[0120] exist Figure 6C In the middle, the first steering angle θ S1 The second steering angle is 20° and θ S2 The first steering angle is 15°. The first steering angle corresponds to point 621 on the main lobe. At point 621, the received power (in dB) is -0.5930. The second steering angle corresponds to point 622 on the main lobe. At point 622, the received power (in dB) is -1.3302. From... Figure 6CIn the above, the difference in power received between points 621 and 622 (in dB) is 0.7372 dB. With equations (15) to (19) replacing all known variables, the calculated Δθ1 is -8.7582°, therefore the calculated AoA is θ. S1 +Δθ1 = 11.2418°. Therefore, the actual AoA can be estimated based on the ratio between the power received at the second steering angle and the power received at the first steering angle, and vice versa. In this example, even though the actual AoA is far from both the first and second steering angles, the calculated AoA still provides a relatively accurate prediction of the actual AoA.

[0121] Assuming the channel between the signal source and receiver is an additive white Gaussian noise (AWGN) channel, the noise in the system will remain constant when the steering angle changes slightly. Therefore, the ratio between the carrier signals at the two measurement periods (first steering angle and second steering angle) is the same as the ratio between their SNR. That is, the ratio of SNR2 / SNR1 or SNR... 2,dB With SNR 1,dB The difference between them has the same meaning as the ratio between carrier signals. That is, all power-related information can be represented by, for example, SNR, BER, C / N, EVM, and / or a measure of the power of the received signal. Different measures may be applied in embodiments of the invention.

[0122] Based on the above, some extended methods can be derived. First, the estimated change in AoA can be provided based on the SNR ratio obtained from the second steering angle and the first steering angle, and based on the SNR ratio obtained from the third steering angle and the second steering angle. As described in steps S302, S304, and S306, the phased array can iteratively calculate and update the new AoA based on the new steering angle and the corresponding SNR ratio. The retrieved AoAs (each or combination) can serve as input data for Kalman filtering to predict future AoA. Furthermore, even if the predicted AoA is not exactly the correct AoA, the proposed method can indicate the approximate direction of the correct AoA.

[0123] Figure 7A and Figure 7B A schematic diagram illustrating an example of the convergence results provided by the proposed method according to an embodiment of the invention for fast tracking. Figure 7A and Figure 7B In this case, AoA is 10°.

[0124] Please refer to Figure 7A For example, if the predicted AoA is 18°, then the actual AoA is 10°. A first example can be found in... Figure 7A The first steering angle observed was 18° and the second steering angle was 13°. The first steering angle corresponds to main lobe 71. The second steering angle corresponds to main lobe 72. The power at point 701 on main lobe 71 and the power at point 702 on main lobe 72 can be obtained respectively. At point 701, the received power (in dB) is -1.2024dB. At point 702, the received power (in dB) is -0.4504dB. For a phased array with four antenna elements (N=4) and a spacing d=λ / 2, the coefficient is k=-0.0135. Based on the obtained power ratio (SNR ratio), the AoA calculated based on equations (15) to (19) is 9.2796°. If the third steering angle is chosen to be 9°, then the AoA calculated based on the power at 13° and the power at 9° is 9.9311°.

[0125] Please refer to Figure 7B Similarly, the second instance can be found in... Figure 7B The first steering angle observed was 18° and the second steering angle was 23°. The first steering angle corresponds to main lobe 71. The second steering angle corresponds to main lobe 73. The power at point 701 on main lobe 71 and the power at point 703 on main lobe 73 can be obtained respectively. At point 701, the received power (in dB) is -1.2024dB. At point 703, the received power (in dB) is -2.668dB. According to the same method based on equations (15) to (19), the calculated AoA is 6.8654°, which indicates the correct side (left side). If the third steering angle is chosen to be 7°, then the AoA calculated based on the power at 18° and the power at 7° is 9.6832°. Therefore, the method is able to produce a convergent result with S302 from the AoA calculated in S207. Figure 2 and Figure 3 The proposed method can be applied to real-time applications, and its convergence effect is beneficial for fast tracking in practical use. The method is applicable to phased arrays using either analog or digital beamforming architectures.

[0126] Figure 8This is a schematic diagram of a phased array using an analog beamforming architecture according to an embodiment of the present invention. In the analog beamforming architecture, the phased array 80 may include a digital processor 81, an AD / DA converter 82, a aggregator 83, multiple mixers MX, multiple phase shifters PHS, multiple gain-controlled amplifiers GCA, and multiple antenna elements ANT. The digital processor 81 is coupled to the AD / DA converter 82. The AD / DA converter is coupled to the multiple mixers MX. In analog beamforming, the phased array 80 receives signals in different time slots. Specifically, the phased array 80 can be turned to a first turning angle to receive a first signal in a first time slot, and then the phased array 80 can be turned to a second turning angle to receive a second signal in a second time slot. In a previous embodiment, the first signal and the second signal both come from the same signal source to determine the AoA of the signal from said signal source. However, the first signal and the second signal may come from different signal sources. The gain-controlled amplifiers GCA adjust the gain of the signals received from the antenna elements ANT respectively. After the received signal passes through the phase shifter PHS and the mixer MX, the aggregator 83 aggregates the signal and feeds the aggregated signal into the AD / DA converter 82. The AD / DA converter 82 then converts the signal into digital data, which is further processed by the digital processor 81. It should be noted that an analog beamforming architecture may require only one AD / DC for multiple antenna elements ANT, but the signals must be received in different time slots.

[0127] Figure 9 This is a schematic diagram of a phased array using a digital beamforming architecture according to an embodiment of the present invention. In the digital beamforming architecture, the phased array 90 may include a digital processor 91, a plurality of AD / DA converters 92, a plurality of mixers MX, a plurality of amplifiers AMP, and a plurality of antenna elements ANT. The digital processor 91 is coupled to the plurality of AD / DA converters 92. Signals received from the antenna elements ANT pass through their corresponding amplifiers AMP and mixers MX, respectively. Then, the plurality of AD / DA converters 92 convert the signals into digital data to be further processed by the digital processor 91.

[0128] In one embodiment, if the antenna array uses digital beamforming technology, then it is not necessary to receive signals in different time slots. Steps S201 and S203 can be accomplished in the baseband by digitally changing the steering angle and performing the same processing in steps S205 to S207 shown above. Specifically, the array receives the first sequence of wireless signals SEQ1. Then, the digital processor 91 applies a first set of steering setting parameters to SEQ1 such that the array appears to be at the first steering angle θ. S1The system then redirects to receive SEQ1. Simultaneously, SEQ1 is stored in, for example, a non-transient memory of the digital processor 91 for further processing. Next, as the digital processor 91 continues to apply the first set of redirection settings parameters to a sequence of received signals, another processor or thread in the same processor applies a second set of redirection settings parameters to SEQ1, making SEQ1 appear to be generated by a second redirection angle θ. S2 The array receives the signal. In one embodiment, C / N1 and C / N2 are then used to perform step S205 to obtain the AoA of SEQ1. In this embodiment, C / N1 and C / N2 involve the same sequence of signals SEQ1, thus eliminating environmental factors that affect C / N or power and therefore the predicted AoA will be closer to the actual AoA.

[0129] The foregoing embodiments assume that the signal from the signal source remains constant during the measurement. For example... Figure 2 and Figure 3 The method for measuring AoA described herein can generally be applied to communication devices that include a phased array 80 using analog beamforming or a phased array 90 using digital beamforming.

[0130] Figure 10 This is a block diagram of a communication device according to an embodiment of the present invention. See also... Figure 10 The communication device 100 may include, but is not limited to, a transceiver 110, a processor 120, and a storage medium 130. The processor 120 is coupled to the transceiver 110 and the storage medium 130.

[0131] Transceiver 110 is coupled to processor 120. Transceiver 110 can receive DL signals and transmit UL signals. Transceiver 110 can perform low-noise amplification (LNA), impedance matching, analog-to-digital (ADC) conversion, digital-to-analog (DAC) conversion, mixing, up-conversion, filtering, amplification, and / or similar operations. Transceiver 110 may include a phased array 80 using analog beamforming or a phased array 90 using digital beamforming, and the phased array may include one or more antenna elements for transmitting and receiving omnidirectional or directional antenna beams.

[0132] Processor 120 is, for example, a Central Processing Unit (CPU) or other programmable general-purpose or special-purpose microprocessor, digital signal processor (DSP), programmable controller, application-specific integrated circuit (ASIC), graphics processing unit (GPU), or other similar components, or a combination of the above. Processor 120 may be configured to perform methods for measuring AoA, such as... Figure 2 and Figure 3 As described in the text.

[0133] Storage medium 130 is coupled to processor 120 and is, for example, any type of fixed or removable random access memory (RAM), read-only memory (ROM), flash memory, hard disk drive (HDD), solid state drive (SSD), or similar components, or combinations thereof. Storage medium 130 stores multiple modules or programs for access by processor 120, enabling processor 120 to perform various communication functions of communication device 100.

[0134] The communication device 100 may be a user equipment in a communication system. The term "user equipment" (UE) in this invention can refer to, for example, a mobile station, an advanced mobile station (AMS), a server, a client, a desktop computer, a laptop computer, a network computer, a workstation, a personal digital assistant (PDA), a tablet personal computer (PC), a scanner, a telephone device, a pager, a camera, a television, a handheld video game device, a music device, a wireless sensor, etc. In some applications, the UE may be a fixed computer device operating in mobile environments such as buses, trains, airplanes, ships, and automobiles.

[0135] The communication device 100 may be a base station in a communication system. The term "base station" (BS) in this invention may be synonymous, for example, with variations or subvariants of "gNodeB" (gNodeB; gNB), "eNodeB" (eNodeB; eNB), Node B, advanced BS (ABS), transmission reception point (TRP), unlicensed TRP, base transceiver system (BTS), access point, home BS, relay station, scatterer, repeater, intermediate node, intermediary, satellite-based communication BS, etc.

[0136] In more complex systems with two devices (the base station (STA) and the user equipment (UE)) communicating with each other, the transmitted signal power can vary from time to time because the turning angle of the signal source can be changed to pursue better communication quality.

[0137] Figure 11A This is a schematic diagram of a communication system with base station scanning user equipment according to an embodiment of the present invention. For example, see... Figure 11A The base station STA can perform a scan from beam 1101a to beam 1101b to establish communication with the UE. In the first phase, the base station STA performs a scan at a turning angle θ corresponding to beam 1101a. S1,STA Operation. Subsequently, in the second phase, the base station STA switches to a different steering angle θ corresponding to beam 1101b. S2,STA .

[0138] Figure 11B This is a schematic diagram of a communication system with a user equipment scanning base station according to an embodiment of the present invention. For example, see... Figure 11B The UE can perform a scan from beam 1102a to beam 1102b to establish communication with the STA. In the first phase, the UE uses a turning angle θ corresponding to beam 1102a. S1,UE Operation. Subsequently, in the second phase, the base station STA switches to a different steering angle θ corresponding to beam 1102b. S2,UE .

[0139] Figure 11C This is a schematic diagram of a communication system according to an embodiment of the present invention, in which a base station and user equipment scan each other. Figure 11C In this process, when the base station (STA) scans the user (UE), the UE also scans the base station. In the first phase, the base station uses a turning angle θ... S1,STA Operation, and the UE operates at a steering angle θ S1,UE Operation. In the second phase, the base station operates at a turning angle θ. S1,STAOperation, and the UE operates at a steering angle θ S1,UE operate.

[0140] It should be noted that for the base station STA measuring the AoA of the UE, the assumptions in equations (7) to (11) may not necessarily hold, because the UE's turning angle changes from θ. S1,UE Change to θ S2,UE .

[0141] In these scenarios, the packets transmitted from the STA to the UE may further include information such as the steering angle, array size, and the estimated AoA measured by the STA. With this information, the UE can evaluate the antenna gain of the STA in the direction from the STA to the UE. Through communication between the base station STA and the UE, the base station STA can obtain additional information, such as the AoA of the base station STA evaluated by the UE and / or the steering angle of the UE at different stages. Therefore, in the measurement of the UE's AoA, this additional information can be used to compensate for errors caused by changes in the UE's steering angle.

[0142] Given the received power P r The relationship between the transmitted signal Pt and the signal Pt is:

[0143]

[0144] Here, θ S,TX θ refers to the turning angle of the signal source (i.e., the base station STA). AoD θ refers to the swivel angle of the receiver as seen through the signal source (i.e., the UE). S,RX The angle θ refers to the turning angle of the receiver. AoA,RX Refers to AoA, G ​​as seen through the receiver TX and G RX Let λ represent the power gain of the signal source and receiver, respectively, λ represent the wavelength of the signal, and R represent the distance between the signal source and receiver. In this example, it is assumed that the distance remains constant during this short time, the wavelength of the signal remains constant despite a slight change, and the transmitted signal P... r The power also remains constant. Therefore, when G TX (θ S,TX ,θ AoD ) and θ S,RX When θ is known, it can be obtained precisely. AoA,RX In one embodiment, the UE can be considered as a signal source and the base station as a receiver, and vice versa.

[0145] Figure 12 This is a schematic diagram of a two-dimensional phased array according to an embodiment of the present invention. Figure 2 and Figure 3 The method for measuring AoA described in the embodiments can also be applied to two-dimensional phased arrays. For example, such as Figure 12 As shown, the two-dimensional phased array can contain MN antenna elements. These antenna elements can be arranged at a uniform spacing of 2 along the x-axis and y-axis, respectively. In this configuration, a small HPBW can lead to a large number of iterations in calculating the AoA. However, the proposed method requires less scan time and is more efficient because it requires only a smaller amount of data and computation to obtain a satisfactory AoA evaluation.

[0146] In view of the foregoing description, the present invention provides a method for measuring the angle of arrival (AoA) using a steerable phased array. Embodiments of the invention disclose a parabolic approximation of the array factor for the beam radiation pattern. The method provides convergent results for fast tracking when the AoA is measured quickly. The method is applicable to both analog and digital beamforming architectures and can operate in real-time applications of device or beam tracking.

Claims

1. A method for measuring the angle of arrival (AoA) using a steerable phased array, comprising: Signals are received through the steerable phased array having a first steering angle and a second steering angle; Obtain the first power-related information (PRI1) of the signal corresponding to the first steering angle; Obtain the second power-related information (PRI2) of the signal corresponding to the second steering angle; as well as Calculating the angle of arrival of the signal based on the ratio of the first power-related information and the second power-related information includes: in response to the first steering angle and the first difference angle calculating the angle of arrival, wherein the first difference angle by calculating: ,in The first steering angle, This is the second steering angle. The difference between the first steering angle and the second steering angle, and the coefficient. , as well as for wherein is a decibel value of a ratio between the first power-related information and the second power-related information, and m is a real number, The first steering angle is different from the second steering angle, and the absolute difference between the first steering angle and the second steering angle is less than the first zero-point beamwidth / 2.

2. The method for measuring the angle of arrival using a steerable phased array according to claim 1, wherein the step of receiving the signal via the steerable phased array having the first steering angle and the second steering angle comprises: The phased array is switched to the first steering angle to receive the signal in the first time slot; as well as The phased array is switched to the second steering angle to receive the signal in a second time slot immediately following the first time slot.

3. The method for measuring the angle of arrival using a steerable phased array according to claim 1, wherein the step of receiving the signal via the steerable phased array having the first steering angle and the second steering angle comprises: The signal is received by N selected antenna elements in the phased array to obtain N signal streams corresponding to the first time slot; Before aggregating the N signal streams, a first set of parameters is applied to the N signal streams to digitally apply the first steering angle to the aggregating signal; as well as Before aggregating the N signal streams, a second set of parameters is applied to the N signal streams to digitally apply the second steering angle to the aggregated signal.

4. The method for measuring the angle of arrival using a steerable phased array according to claim 1, wherein the first power-related information and the second power-related information are represented by a metric selected from a group consisting of received power, signal-to-noise ratio, error vector magnitude, bit error rate, and carrier-to-noise ratio.

5. The method for measuring the angle of arrival using a steerable phased array according to claim 1, wherein: ， in The number of antenna elements. The spacing between two adjacent antenna elements. The wavelength of the signal is denoted as .

6. The method for measuring the angle of arrival using a steerable phased array according to claim 1, wherein the absolute difference between the first steering angle and the second steering angle is less than half-power beamwidth / 2.

7. The method for measuring the angle of arrival using a steerable phased array according to claim 6, wherein the absolute difference between the first steering angle and the second steering angle is less than half-power beamwidth / 4.

8. The method for measuring the angle of arrival using a steerable phased array according to claim 1, further comprising: The calculated angle of arrival is used as the third steering angle to receive the signal; Obtain the third power-related information (PRI3) of the signal corresponding to the third steering angle; as well as The angle of arrival is updated based on the third power-related information and the third steering angle.

9. The method for measuring the angle of arrival using a steerable phased array according to claim 8, wherein the step of updating the angle of arrival further comprises: Calculate the new angle of arrival based on the third power-related information and at least one of the first power-related information and the second power-related information; as well as The angle of arrival is updated using the new angle of arrival.

10. The method for measuring angle of arrival using a steerable phased array according to claim 8, wherein the step of updating the angle of arrival further comprises: The steering angle with the maximum power-related information is calculated based on three pairs of parabolic curves obtained from the first steering angle, the second steering angle, and the third steering angle, as well as the corresponding first power-related information, second power-related information, and third power-related information; and The angle of arrival is updated using the calculated steering angle.

11. A communication device, comprising: Transceivers, including steerable phased arrays; Storage media; as well as A processor, coupled to the transceiver and the storage medium, wherein the processor is configured to: Signals are received through the steerable phased array having a first steering angle and a second steering angle; Obtain the first power-related information (PRI1) of the signal corresponding to the first steering angle; Obtain the second power-related information (PRI2) of the signal corresponding to the second steering angle; as well as Calculating the angle of arrival of the signal based on the ratio of the first power-related information and the second power-related information includes: in response to the first steering angle and the first difference angle calculating the angle of arrival, wherein the first difference angle by calculating: ,in The first steering angle, This is the second steering angle. The difference between the first steering angle and the second steering angle, and the coefficient. , as well as for in Let m be the decibel value representing the ratio between the first power-related information and the second power-related information, where m is a real number. The first steering angle is different from the second steering angle, and the absolute difference between the first steering angle and the second steering angle is less than the first zero-point beamwidth / 2.

12. The communication apparatus of claim 11, wherein the processor is further configured to: The calculated angle of arrival is used as the third steering angle to receive the signal; Obtain the third power-related information (PRI3) of the signal corresponding to the third steering angle; and The angle of arrival is updated based on the third power-related information and the third steering angle.

13. The communication apparatus of claim 12, wherein the processor is further configured to: Calculate the new angle of arrival based on the third power-related information and at least one of the first and second power-related information; and The angle of arrival is updated using the new angle of arrival.

14. The communication apparatus of claim 12, wherein the processor is further configured to: The steering angle with the maximum power-related information is calculated based on three pairs of parabolic curves obtained from the first steering angle, the second steering angle, and the third steering angle, as well as the corresponding first power-related information, second power-related information, and third power-related information; and The angle of arrival is updated using the calculated steering angle.

15. The communication apparatus according to claim 11, wherein: ， wherein is the number of antenna elements, is the spacing between two adjacent antenna elements, is the wavelength of the signal.

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