KR102122124B1 - Adaptive beamforming method and apparatus for embodying the same - Google Patents

Abstract

Disclosed is an adaptive beamforming method capable of improving the processing speed by increasing the speed of convergence when performing iteration, and an apparatus for implementing the same. In the adaptive beamforming method, (a) N signal arrival direction processors generate N second signals by multiplying N first signals received through N smart antenna arrays by a weight vector, respectively. And, (b) generating a third signal by receiving the N second signals and multiplying the N second signals by multiplying the coupling constants, and (c) generating the third signal. 2 an adder receiving the third signal, subtracting the third signal from a reference signal projecting the third signal as the nearest signal coordinate, and calculating a common error value, and (d) N The Least Mean Squares receive the common error value, multiply the step size parameter set by the common error value and the N first signals, and add the weight vector to generate a new weight vector, and the new And providing a weight vector to the N signal arrival processors.

Description

ADAPTIVE BEAMFORMING METHOD AND APPARATUS FOR EMBODYING THE SAME

The present invention relates to an adaptive adaptive beamforming method and an apparatus for implementing the same, and more particularly, to an adaptive beamforming method of a receiver having N smart antennas and an apparatus for implementing the same.

Spectral efficiency and reliability are limited by multipath fading, delay spread and co-channel interference in wireless communication systems. In recent years, there has been a lot of research on angular diversity to overcome multipath fading in the spatial domain. In particular, by using a smart antenna in various ways, it is possible to improve the performance of a wireless communication system. Adaptive beamforming is one of the most important smart antenna technologies that can be widely used in the wireless communication field.

The requirements of wireless communication systems are expected to increase explosively in the near future. One of the possible solutions is that an adaptive beamforming system is being requested at the receiver side in order to satisfy the needs for future communication systems.

Republic of Korea Patent Publication No. 10-2013-0017932

The problem to be solved by the present invention is to provide an adaptive beamforming method and an apparatus for realizing the adaptive beamforming method in which the speed of convergence is increased when the repetition is performed, so that the processing speed can be improved.

An adaptive beamforming method according to an exemplary embodiment of the present invention for solving this problem includes: (a) N signal arrival direction processors, N first signals respectively received through N smart antenna arrays Multiplying by a weight vector to generate N second signals, and (b) a first adder receives the N second signals, and multiplies the N second signals by multiplying each combination constant. By doing so, the step of generating a third signal, and (c) the second adder receives the third signal and projects the third signal from the reference signal projecting the third signal as the nearest signal coordinate. Calculating a common error value by subtracting, and (d) N minimum mean squares, respectively, receiving the common error value, multiplying the step size parameter set by the common error value and the N first signals, And summing the weight vectors to generate a new weight vector and providing the new weight vector to the N signal arrival processors.

On the other hand, according to the adaptive beamforming method according to another embodiment of the present invention, the N signal arrival direction processor, the first adder, the second adder, and the N minimum average multiplier, the number of times set using the new weight vector Steps (a) to (d) may be repeated.

On the other hand, according to the adaptive beamforming method according to another embodiment of the present invention, the N signal arrival direction processor, the first adder, the second adder, and the N minimum average squarer, using the new weight vector (a ) To (d) can be repeated until the weight vector converges below a set value.

In addition, the step size parameter may be determined below an inverse of a value twice the trace value of the correlation matrix formed by using the N first signals and its Hermit values.

The adaptive beamforming apparatus according to an exemplary embodiment of the present invention includes N signal arrival direction processors, a first adder, a second adder, and N minimum mean squares. The N signal arrival direction processors generate N second signals, respectively, by multiplying N first signals received through N smart antenna arrays by a weight vector. The first adder generates the third signal by receiving the N second signals and multiplying the N second signals by multiplying the coupling constants. The second adder receives the third signal, and calculates a common error value by subtracting the third signal from a reference signal projecting the third signal as the nearest signal coordinate. Each of the least-squares multipliers receives the common error value, multiplies the step size parameter set by the common error value and the N first signals, and adds the weight vector to generate a new weight vector, and the A new weight vector is provided to the N signal arrival processors.

In this way, the adaptive beamforming method and the adaptive beamforming apparatus according to the present invention have N signal arrival direction processors using the same common error value, compared to N signal arrival direction processors using each error value. In the case of repetition, the speed of convergence increases, so that the processing speed can be improved.

In addition, if repeated the same number of times, accuracy may be improved.

Fig. 1 is a flow chart showing an adaptive beamforming method according to an exemplary embodiment of the present invention.
Fig. 2 is a flow chart showing an adaptive beamforming method according to another exemplary embodiment of the present invention.
3 is a diagram illustrating the adaptive beamforming apparatus and method illustrated in FIGS. 1 and 2.
FIG. 4 is for comparing the method in which the conventional N signal arrival direction processors use each error value and the method in which the N signal arrival direction processors according to the present invention use the same common error value. It is a graph showing the relationship of square error.
FIG. 5 is a method for comparing a method in which N conventional signal arrival direction processors use each error value and a method in which N signal arrival direction processors according to the present invention use the same common error value. It is a graph showing the relationship between Eit Error Ratio.

The present invention can be applied to various changes and may have various forms, and specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosure form, and it should be understood that it includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing each drawing, similar reference numerals are used for similar components. In the accompanying drawings, the dimensions of the structures may be exaggerated than actual in order to clarify the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

The terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as “include” or “have” are intended to indicate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, or one or more other features or It should be understood that the existence or addition possibilities of numbers, steps, actions, components, parts or combinations thereof are not excluded in advance. Also, A and B means'connected' and'joined', in addition to A and B being directly connected or joined, other components C are included between A and B so that A and B are connected or joined. It includes things.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Terms such as those defined in a commonly used dictionary should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not. Also, in the claims of a method invention, unless each step is clearly bound to the order, the order of each step may be reversed.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

1 is a flow chart showing an adaptive beamforming method according to an exemplary embodiment of the present invention, and FIG. 2 is a flow chart showing an adaptive beamforming method according to another exemplary embodiment of the present invention.

1 and 2, according to an adaptive beamforming method according to an exemplary embodiment of the present invention, first, N signal arrival direction processors, each N received through N smart antenna arrays The first signals are multiplied by a weight vector to generate N second signals, respectively (steps S110 and S210).

Thereafter, the first adder receives the N second signals and multiplies the N second signals by multiplying and combining them, thereby generating a third signal (steps S120 and S220).

Thereafter, the second adder receives the third signal and calculates a common error value by subtracting the third signal from the reference signal projecting the third signal as the nearest signal coordinate (step S130, S230).

Subsequently, the N least-squares multipliers receive the common error value, multiply the step size parameter set by the common error value and the N first signals, and add the weight vector to generate a new weight vector, , The new weight vector is provided to the N signal arrival processors (steps S140 and S240).

Thereafter, in one embodiment of the present invention illustrated in FIG. 1, the N signal arrival direction processors may repeatedly perform steps S110 to S140 as many times as set by using the new weight vector.

Alternatively, in another embodiment of the present invention shown in FIG. 2, the N signal arrival direction processors use the new weight vector (step S110 to step S140, the size of the common error value is a set value) It can be repeated until the following.

This process will be described in more detail with reference to FIG. 3 below.

3 is a diagram illustrating the adaptive beamforming apparatus and method illustrated in FIGS. 1 and 2.

Referring to Figure 3, the adaptive beamforming apparatus according to the present invention, N signal arrival direction processor (Processor of DoA 1 ~ Processor of DoA N), the first adder (A1), the second adder (A2) and N Includes the minimum mean squares of dogs (LMS 1 to LMS N).

The N signal arrival direction processors (Processor of DoA 1 to Processor of DoA N) are N first signals (x(k)) respectively received through N smart antenna arrays as shown in Equation 1 below. Multiplied by a weight vector (w) to generate N second signals (y ₁ (k) to y _N (k)).

Thereafter, the first adder A1 receives the N second signals (y ₁ (k) to y _N (k)) and, as shown in Equation 2 below, the N second signals (y ₁ (k) to y _N (k)) is multiplied by the sum of each of the coupling constants (c ₁ to c _N ) to generate a third signal (y _c (k)).

Thereafter, the second adder A2 receives the third signal y _c (k) and, as shown in Equation 3 below, the third signal y _c (k) is the nearest signal coordinate. The common error value e(k) is calculated by subtracting the third signal y _c (k) from the projection reference signal d(k).

In Equation 3, τ _i denotes a time delay value along each path.

Subsequently, the N Least Mean Squares (LMS 1 to LMS N) respectively receive the common error value (e(k)) and, as shown in Equation 4 below, the common error value (e(k)) ), multiplying the step size parameter (μ) and the N first signals, and adding the weight vector (w(k)) to generate a new weight vector (w(k+1)), and the new weight vector (w(k+1)) is provided to the N signal arrival direction processors (Processor of DoA 1 to Processor of DoA N).

On the other hand, the step size parameter (μ), as shown in Equation 5 below, the correlation matrix R formed using the N first signals and its Hermit values (Equation below) It can be determined below the reciprocal of the value twice the trace value of (see 6).

In Equation 6, τ _i denotes a time delay value along each path.

Thereafter, NN processors (Processor of DoA 1 to Processor of DoA N), first adder (A1), second adder (A2), and N minimum mean squares (LMS 1 to LMS N) are performed in advance. Iterate the old process.

At this time, the number of repetitions may be set by the user such as 100 times, 200 times, or the like, and may be repeatedly performed until the weight vector converges below a set value.

FIG. 4 is for comparing the method in which the conventional N signal arrival direction processors use the respective error values and the method in which the N signal arrival direction processors according to the present invention use the same common error value. It is a graph showing the relationship of a square error, and FIG. 5 shows a method in which conventional N signal arrival direction processors use each error value and N signal arrival direction processors according to the present invention have the same common error value. To compare the method using, it is a graph showing the relationship between the signal-to-noise ratio (SNR) and the bit error rate (Eit Error Ratio).

For the simulations of FIGS. 4 and 5, it was assumed that the main signal propagates along four paths with angles of 20°, 0°, -20° and 40°. In addition, the receiver has a uniform linear array (ULA) with an element spacing of λ/2. ULA is connected to four parallel beamforming processors to process the signals separately. In this simulation, BPSK modulation and up to 500 iterations were used.

Simulations were performed to identify performance differences using general error feedback and individual error feedback. 4 and 5 indicate that "scheme A" is a method using conventional individual error feedback and "scheme B" is a method using feedback using a common error value according to the present invention.

4, it can be seen that the convergence speed of the method (scheme B) according to the present invention is superior to that of the conventional method (scheme A). That is, using normal error feedback, stability can be obtained faster than individual ones.

5 shows the bit error rate (BER) performance when the system uses 200 iterations. BER performance of the method according to the invention (scheme B) is BER = 10 ^- is 4dB better than the conventional methods (scheme A) ^5. Therefore, these results can clearly confirm the advantages of the method according to the present invention (scheme B) compared to the conventional method (scheme A).

In this way, the adaptive beamforming method and the adaptive beamforming apparatus according to the present invention have N signal arrival direction processors using the same common error value, compared to N signal arrival direction processors using each error value. In the case of repetition, the speed of convergence increases, so that the processing speed can be improved.

In addition, if repeated the same number of times, accuracy may be improved.

In the detailed description of the present invention described above, it has been described with reference to preferred embodiments of the present invention, but those skilled in the art or those skilled in the art will appreciate the spirit of the present invention as set forth in the claims below. And it will be understood that various modifications and changes can be made to the present invention without departing from the technical scope.

Processor of DoA (Direction of Arrival): Processor of signal arrival direction
LMS: Least Mean Square
A1: first adder A2: second adder
x(k): first signal
y ₁ (k) ~ y _N (k): second signal
y _c (k): 3rd signal
d(k): Reference signal
e(k): Error value

Claims (5)

(a) N signal arrival direction processors, generating N second signals by multiplying N first signals received through N smart antenna arrays by a weight vector;
(b) generating a third signal by the first adder receiving the N second signals and multiplying the N second signals by multiplying the respective combination constants;
(c) a second adder receiving the third signal and subtracting the third signal from a reference signal projecting the third signal as the nearest signal coordinate to calculate a common error value; And
(d) N minimum mean squares, each receiving the common error value, multiplying the step size parameter set by the common error value and the N first signals, and adding the weight vector to generate a new weight vector And providing the new weight vector to the N signal arrival processors;
Adaptive beamforming method comprising a.
According to claim 1,
The N signal arrival direction processor, the first adder, the second adder and the N least average squarer, the adaptive characterized in that iteratively repeats the process (a) to (d) a set number of times using the new weight vector Beamforming method.
According to claim 1,
When the N signal arrival direction processor, the first adder, the second adder, and the N least average squarer process (a) to (d) using the new weight vector, when the weight vector converges below a set value Adaptive beamforming method characterized by repeating until.
According to claim 1,
The step size parameter,
Adaptive beamforming method characterized in that it is determined below the reciprocal of twice the value of the trace value of the correlation matrix formed by using the N first signals and its Hermit values.
N signal arrival direction processors that respectively generate N second signals by multiplying N first signals received through N smart antenna arrays by a weight vector;
A first adder for receiving the N second signals and multiplying the N second signals by multiplying the combination constants to generate a third signal;
A second adder for receiving the third signal and subtracting the third signal from a reference signal projecting the third signal as the nearest signal coordinate to calculate a common error value; And
Each receives the common error value, multiplies the step size parameter set by the common error value and the N first signals, adds the weight vector, generates a new weight vector, and adds the new weight vector to the N signals. N minimum mean squares provided to the arrival processor;
Adaptive beamforming apparatus comprising a.

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