Hybrid receiving end phased array arrival angle estimation system

Abstract

The invention belongs to the technical field of integrated circuits, and particularly relates to a hybrid receiving end phased array arrival angle estimation system. The system comprises an antenna array, an analog beam synthesizer, a radio frequency link, an analog-to-digital converter, a digital beam synthesizer and an angle of arrival estimator. The antenna array receives an electromagnetic wave signal sent by the transmitter; the antenna array is divided into a plurality of simulation sub-arrays, each simulation sub-array forms a simulation beam synthesizer, and radio frequency signals of all channels of the sub-array are subjected to simulation beam synthesis; the radio frequency link performs down-conversion on the radio frequency signal subjected to analog beam forming to a base band; the analog-to-digital converter converts the analog signal of the baseband into a digital signal; the digital beam synthesizer weights and accumulates the baseband digital signals to obtain a digital beam synthesis result; and performing arrival angle estimation on a hybrid beam forming result, thereby realizing low-complexity and high-precision arrival angle estimation of the large-scale millimeter wave antenna array.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated circuits, and in particular relates to an angle of arrival estimation system. Background Art

[0002] Angle of arrival estimation is a technology that can determine the spatial position of a device and can be widely used in different scenarios such as wireless communications, radar, acoustic positioning, the Internet of Things, millimeter wave MIMO, etc. The principle of this technology is based on the electromagnetic propagation characteristics of the signal transmitted by the device, that is, the direction of a given signal received by the array antenna determines the phase shift between different receiving channels.

[0003] There are two main methods for arrival angle estimation: parameter estimation and spectral estimation. The former obtains the arrival angle of the input signal by calculating the maximum value of the signal-to-noise-distortion ratio, while the latter, also known as multiple signal classification, estimates the angle by constructing a spatial spectrum. Medium-scale or large-scale receiving antenna arrays using digital beamforming can achieve high-resolution arrival angle estimation at the receiver.

[0004] Since large-scale digital arrays usually have high computational complexity and high cost, hybrid phased arrays have become an option to balance computational complexity, cost and angular resolution. The hybrid phased array used for the receiving end consists of an analog array and a digital array, both of which can perform phase shifting on multi-channel signals. The analog array divided into several subarrays first performs analog phase shifting and analog beam synthesis on the RF signal. The synthesized analog signal is down-converted to baseband through the RF link, and then converted into a digital signal through an analog-to-digital converter. Finally, the digital array performs digital phase shifting and digital beam synthesis. The results of analog beam synthesis and digital beam synthesis are sent to the arrival angle estimation module for angle estimation, and fed back to the previous analog array for phase shift correction.

[0005] The hybrid receiving-end phased array arrival angle estimation system can achieve high-precision and low-complexity arrival angle estimation. Summary of the invention

[0006] The purpose of the present invention is to provide a high-precision, low-complexity hybrid receiving-end phased array arrival angle estimation system.

[0007] The hybrid receiving end phased array arrival angle estimation system proposed by the present invention comprises: an antenna array, an analog beam synthesizer, a radio frequency link, an analog-to-digital converter, a digital beam synthesizer, and an arrival angle estimation module; the antenna array has a total of N antennas, which are evenly distributed; the antenna array is evenly divided into M analog sub-arrays, each sub-array has K antennas, and N=MK is satisfied; each analog sub-array corresponds to an analog beam synthesizer, a radio frequency link, and an analog-to-digital converter; each analog beam synthesizer corresponds to K radio frequency phase shifters and an addition synthesizer; the signal of each analog sub-array passes through The analog beamformer performs analog beamforming, which is then down-converted to an intermediate frequency signal by the RF link; the analog-to-digital converter converts the analog intermediate frequency signal into a digital signal, and sends the analog beamforming result to the arrival angle estimation module for storage; the digital beamforming module performs a second beamforming on the mth signal at this time, m=1, 2..., M, and sends the result to the arrival angle estimation module to calculate the phase shift amount that needs to be corrected by the previous analog beamforming module, and calculate the final arrival angle, thereby realizing low-complexity, high-precision arrival angle estimation for large-scale millimeter-wave antenna arrays.

[0008] In the present invention, the analog beamforming module includes a bandpass filter, a low noise amplifier and a radio frequency phase shifter. The bandpass filter and the low noise amplifier of the kth channel of the mth analog subarray receive the antenna signal x n (t), (n=1…N) are filtered and amplitude compensated, and the phase shift of the RF phase shifter is controlled by the arrival angle estimation module to form a simulated beam focused in a specific direction:

[0009] (1)

[0010] in, is the phase shift of the kth receiving channel of the mth analog subarray. The RF phase shifter makes the synthetic beam of the subarray point to the angle θ m θ m The angle value of should be determined by the M main lobe pointing angles synthesized by the subsequent digital beamforming. m,k (t) is the signal of the kth receiving channel of the mth simulated subarray; for a uniform linear array, x m,k (t) can be written as:

[0011]

[0012] Where d is the spacing of the uniform linear array, θ 0 is the incident angle of the sine wave incident on the uniform linear array, ω c is the carrier angular frequency of the sine wave, and λ is the wavelength.

[0013] In the present invention, the radio frequency link includes a mixer, an intermediate frequency filter, and an intermediate frequency amplifier; the mixer mixes the received analog beamforming result and the local oscillator signal generated by the local oscillator, and then the intermediate frequency filter filters out the high-frequency signal, passes through the intermediate frequency amplifier, and is converted into a digital signal by the analog-to-digital converter:

[0014]

[0015] At this time, the signal angular frequency has been down-converted by the RF link to ω c -ω LO , which is convenient for subsequent digital baseband processing.

[0016] In the present invention, the digital beamforming module includes a digital phase shifter and an adder. M digital phase shifters scan the digital beam under the control of the arrival angle estimation module, and the digital beamforming result is obtained by accumulating and synthesizing through the adder:

[0017]

[0018] in, is the digital phase shift of the mth digital channel. Therefore, the final beamforming result after analog and digital stages is:

[0019]

[0020] The DOA (Direction Of Arrival) problem is equivalent to scanning θ and θ m , so that the absolute value of z[t] is maximized to solve θ 0 .

[0021] The present invention proposes a method of first scanning the angle θ of the digital phase shifter and then scanning the angle θ of the analog phase shifter. m DOA method. That is, first let α m,k =1, the results of digital beam synthesis are:

[0022]

[0023] Observing the above formula, we can find that finding the maximum value of |z′[t]| is equivalent to finding The maximum value of θ arrive Scan between, if the scanning step is stepsize, then the number of weights Q can be defined as The angle at which the maximum value appears in the beam scanning result is the scanning angle θ of the subsequent simulated phase shifter. m Since each of the K RF phase shifters in an analog beamformer can provide a phase shift of [0,2π], solving this equation for the maximum value will produce K DOA estimates θm :

[0024] θ m ={θ m,1 ,θ m,2 ,θ m,3 ,…θ m,K}, (7)

[0025] θ m satisfy Among them, m=1,2,…M; i=1,2,…K.

[0026] After digital beam scanning, the analog phase shifter of each subarray only needs to be set at θ m ={θ m,1 ,θ m,2 ,θ m,3 ,…θ m,K} within the scope of By scanning, the final DOA estimate θ can be obtained. m =θ 0 .

[0027] The hybrid receiving end phased array arrival angle estimation system of the present invention can realize low-complexity and high-precision arrival angle estimation of large-scale millimeter wave antenna arrays because it is based on a hybrid structure of analog and digital arrays. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the hybrid receiving end phased array arrival angle estimation system of the present invention.

[0029] Figure 2 This is a schematic diagram of the beam scanning result.

[0030] Figure 3 The schematic diagram of the circuit of the RF link module.

[0031] Figure 4 This is a schematic diagram of the secondary beam scanning results. DETAILED DESCRIPTION

[0032] The present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, the same elements are represented by similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale. In addition, some well-known parts may not be shown in the drawings.

[0033] Many specific details of the present invention are described below, such as device structure, materials, dimensions, processing technology and techniques, so as to more clearly understand the present invention. However, as those skilled in the art will appreciate, the present invention may be implemented without following these specific details.

[0034] Figure 1 A schematic diagram of the hybrid receiving-end phased array arrival angle estimation system of the present invention is shown.

[0035] The hybrid receiving end phased array arrival angle estimation system 100 proposed by the present invention includes an antenna array, an analog beam synthesizer, a radio frequency link, an analog-to-digital converter, a digital beam synthesizer, and an arrival angle estimation. The antenna array receives the electromagnetic wave signal sent by the transmitter; the antenna array is divided into a number of analog sub-arrays, each analog sub-array constitutes an analog beam synthesizer, and the radio frequency signals of all channels of the sub-array are subjected to analog beam synthesis; the radio frequency link down-converts the radio frequency signal subjected to analog beam synthesis to the baseband; the analog-to-digital converter converts the baseband analog signal into a digital signal; the digital beam synthesizer weights and accumulates the baseband digital signal to obtain the final beam synthesis result; the arrival angle is estimated for the final beam synthesis result, thereby realizing low-complexity and high-precision arrival angle estimation of large-scale millimeter wave antenna arrays.

[0036] Figure 2 This is a schematic diagram of the beam scanning result. Since each angle is searched step by step in the analog domain, each search point requires a new set of data, there is no data storage, and the search range is large. The digital domain scanning results can be stored in ROM, thereby reducing the scanning range. Therefore, this scheme adopts digital domain scanning first, and then analog domain scanning. If N antenna array elements are divided into M sub-arrays, each sub-array has K array elements. The phase shift amount of the mth digital phase shifter d is the spacing of the uniform linear array, and the wavelength is λ. The result of a digital beam scan is K main lobes, of which (N / K-1) are pseudo solutions. The angles θ corresponding to the K solutions are stored in ROM. m,1 ,θ m,2 ,…,θ m,K , and sent to the arrival angle estimation module.

[0037] Figure 3 The circuit diagram of the RF link module is shown in Figure 2. The RF link 200 includes a mixer, an intermediate frequency filter, and an intermediate frequency amplifier. The mixer mixes the received analog beamforming result with the local oscillator signal generated by the local oscillator, and then the intermediate frequency filter filters out the high-frequency signal. After passing through the intermediate frequency amplifier, the analog-to-digital converter converts the signal into a digital signal. m [t]. At this time, the analog beamforming result after signal processing can be stored in the ROM of the arrival angle estimation module.

[0038] Figure 4 The figure is a schematic diagram of the secondary beam scanning result. At this time, the phase shift amount of the digital phase shifter has been determined, and the analog phase shifter performs a secondary scan on the K results generated by the digital beam scanning. Since each subarray has K analog phase shifters, a total of K scans are required. 2 An analog phase shifter. θ m ={θ m,1 ,θ m,2 ,θ m,3 ,…θ m,K},θ m satisfy Where k = 1, 2, ... K; m = 1, 2, ... M; i = 1, 2, ... K. The beam synthesis result obtained by the second scan can be used to search for the final arrival angle.

[0039] In this article, the term "comprises", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that the included series of elements (such as processes, methods, articles or equipment) includes not only those elements, but also other elements not explicitly listed. In the absence of more restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in addition to the included elements.

[0040] In the present invention, the embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Based on the above description, many changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and modify and use it based on the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A hybrid receiving end phased array arrival angle estimation system, characterized in that include: Antenna array, analog beamformer, RF link, analog-to-digital converter, digital beamformer, angle-of-arrival estimation module; The antenna array has a total of N antennas, which are evenly distributed; the antenna array is evenly divided into M analog sub-arrays, each sub-array has K antennas, and N=MK; each analog sub-array corresponds to an analog beam synthesizer, an RF link, and an analog-to-digital converter; each analog beam synthesizer corresponds to K RF phase shifters and an addition synthesizer; the signal of each analog sub-array is subjected to analog beam synthesis by the analog beam synthesizer, and then down-converted to an intermediate frequency signal by the RF link; The analog-to-digital converter converts the analog intermediate frequency signal into a digital signal and sends the analog beamforming result to the arrival angle estimation module for storage; The digital beamforming module performs a second beamforming on the mth signal at this time, m = 1, 2, ..., M, and sends the result to the arrival angle estimation module to calculate the phase shift amount that needs to be corrected by the previous analog beamforming module, and calculate the final arrival angle, thereby realizing low-complexity and high-precision arrival angle estimation for large-scale millimeter-wave antenna arrays.

2. The hybrid receiving end phased array arrival angle estimation system according to claim 1, characterized in that: The analog beamforming module includes a bandpass filter, a low noise amplifier and a radio frequency phase shifter; the bandpass filter and the low noise amplifier of the kth channel of the mth analog subarray receive the antenna signal x n (t), (n=1…N) are filtered and amplitude compensated, and the phase shift of the RF phase shifter is controlled by the arrival angle estimation module to form a simulated beam focused in a specific direction: in, is the phase shift of the kth receiving channel of the mth analog subarray. The RF phase shifter makes the synthetic beam of the subarray point to the angle θ m θ m The angle value of is determined by the M main lobe pointing angles synthesized by the subsequent digital beamforming; m,k (t) is the signal of the kth receiving channel of the mth simulated subarray; for a uniform linear array, x m,k (t) is written as: Where d is the spacing of the uniform linear array, θ0 is the incident angle of the sine wave incident on the uniform linear array, ω c is the carrier angular frequency of the sine wave, and λ is the wavelength.

3. The hybrid receiving end phased array arrival angle estimation system according to claim 2, characterized in that: The RF link includes a mixer, an intermediate frequency filter, and an intermediate frequency amplifier; the mixer mixes the received analog beamforming result with the local oscillator signal generated by the local oscillator, and then the intermediate frequency filter filters out the high-frequency signal, passes through the intermediate frequency amplifier, and is converted into a digital signal by the analog-to-digital converter: At this time, the signal angular frequency has been down-converted by the RF link to ω c -ω LO , which is convenient for subsequent digital baseband processing.

4. The hybrid receiving end phased array arrival angle estimation system according to claim 3, characterized in that: The digital beamforming module includes a digital phase shifter and an adder; the digital phase shifter scans the digital beam under the control of the arrival angle estimation module, and the digital beamforming result is obtained by accumulating and synthesizing through the adder: in, is the digital phase shift of the mth digital channel; so the final beamforming result after analog and digital stages is: The DOA problem is equivalent to scanning θ and θ m , so that the absolute value of z[t] is maximized to solve θ0.

5. The hybrid receiving end phased array arrival angle estimation system according to claim 4, characterized in that: The method to solve θ0 is: First scan the angle θ of the digital phase shifter, then scan the angle θ of the analog phase shifter m That is, let α m,k =1, the results of digital beam synthesis are: According to the above formula, finding the maximum value of |z′[t]| is equivalent to finding The maximum value of θ arrive Scan between, if the scanning step is stepsize, then the number of weights Q is defined as The angle at which the maximum value appears in the beam scanning result is the scanning angle θ of the subsequent simulated phase shifter. m ; Since each of the K RF phase shifters in an analog beamformer can provide a phase shift of [0,2π], solving this equation for the maximum value will produce K arrival angle estimates θ m : i m ={θ m,1 ,i m,2 ,i m,3 ,…θ m,K }, (7) θ m satisfy Wherein, m=1,2,…M;i=1,2,…K; After digital beam scanning, the analog phase shifter of each subarray is set at θ m ={θ m,1 ,θ m,2 ,θ m,3 ,…θ m,K } within the scope of Scanning is performed to obtain the final arrival angle estimate θ m =θ0.

Images