KR20190012532A - Method and Apparatus for Estimating Incidence Angle of Received Signal based on codebook in Multiple-Input Multiple-Output Communication Systems - Google Patents

Abstract

Disclosed are a method and an apparatus for estimating an incidence angle of a received signal based on a codebook in a multiple-input multiple-output (MIMO) communication system. According to an embodiment of the present invention, a method for estimating an incidence angle of a received signal comprises the steps of: quantizing a signal received by a MIMO antenna by using an analog-digital converter (ADC); calculating a correlation value for each of code words of a codebook pre-generated for the quantized received signal and an estimated incidence angle; and estimating an incidence angle of the received signal based on the calculated values, wherein the quantizing step can quantize the received signal in 1-bit by using a 1-bit ADC.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for estimating the angle of incidence of a codebook-based received signal in a multi-antenna communication system,

The present invention relates to a technique for estimating the angle of incidence of a received signal in a multi-antenna system, and more particularly, to a technique for estimating the angle of incidence of a received signal based on a codebook in a multi- A method for estimating a signal incident angle, and a device therefor.

Future communication systems are expected to use the millimeter wave band to use very wideband based on a massive multiple-input multiple-output (MIMO) system with multiple antennas installed in the transceiver. Currently, the MIMO system has about 4 ~ 10 antennas installed in the transceiver, so there is no problem to connect each radio frequency chain with good performance to each antenna.

However, a large MIMO system that installs a large number of antennas in a transceiver has a problem that it is difficult to connect a good performance RF chain to each antenna due to a large power consumption and a price problem.

Recently, there have been a lot of studies to develop a signal reception method on the assumption of a large MIMO system in which an RF chain having low cost and deteriorated performance is connected. Especially, a 1-bit analog digital converter (1-bit ADC) Research on large MIMO systems using low resolution ADCs is underway.

That is, in a large MIMO system, a 1-bit ADC for a real part and an imaginary part for each reception antenna is increasingly used because of its small complexity. However, since a 1-bit ADC does not operate linearly, a multiple-receiving antenna system operating as a 1-bit ADC has a disadvantage that it is not easy to analyze as compared to a multi-receiving antenna system operating with a conventional high resolution ADC have.

Likewise, a large MIMO system operating as a 1-bit ADC is not as easy to estimate the angle of incidence of a received signal as compared to multiple receive antenna systems operating with conventional high resolution ADCs. However, since the angle of incidence is important information of the wireless channel, it is difficult to communicate effectively without knowing it. Therefore, for smooth communication, it is necessary to develop an algorithm that can estimate the angle of incidence. Although a minimum mean square error (MMSE) incidence angle estimation algorithm is known to minimize a mean square error (MSE) in a multi-receiving antenna system operating as a 1-bit ADC, And has a disadvantage in that the versatility is low because of its large complexity.

Therefore, in the present invention, in a line-of-sight (ULA) uniformly linear array (ULA) multiple receive antenna system in which a 1-bit ADC for the real part and the imaginary part is connected for each receive antenna, We propose a low - complexity codebook - based algorithm.

Embodiments of the present invention provide a method and apparatus for estimating a received signal incidence angle that can improve estimation accuracy of an incident angle of a received signal based on a codebook in a multiple receive antenna system that has been subjected to 1-bit quantization.

In particular, embodiments of the present invention are based on a linear-line-of-sight (ULA) uniform array (ULA) with 1-bit quantization in a channel having radio channel fading and AWGN (Additive White Gaussian Noise) A method and apparatus for estimating the angle of incidence of a received signal that can estimate the angle of incidence of a received signal based on a codebook from a quantized received signal when using a multiple receive antenna system.

A method for estimating a received signal angle of incidence according to an exemplary embodiment of the present invention includes quantizing a received signal received through multiple receive antennas using an analog-to-digital converter; Calculating a correlation value for each of the code words of the codebook generated in advance with respect to the quantized received signal and the estimated incident angle; And estimating an incident angle of the received signal based on the calculated correlation values.

The quantizing step may perform 1-bit quantization of the received signal using a 1-bit analog-to-digital converter.

Further, a method for estimating a received signal angle of incidence according to an embodiment of the present invention includes: dividing a predetermined incident angle range into a first section; And generating the codebook for the 1-bit quantized received signal using a code word for each of the divided first incident angular intervals, wherein the step of calculating comprises: And a correlation value for each of the word and the 1-bit quantized received signal.

Furthermore, the method for estimating a received signal angle of incidence according to an embodiment of the present invention includes: dividing a predetermined incident angle range into a first section; Generating a codebook for the 1-bit quantized received signal using a code word for each of the divided first incident angular intervals; And generating an extended codebook by expanding the generated codebook by a predetermined number of times, wherein the step of calculating includes calculating a correlation between each of the code words of the extended codebook and the 1-bit quantized received signal, The value can be calculated.

Wherein the step of generating the codebook comprises the steps of: if there are identical code words among the code words for each of the divided first incident angular intervals, excluding the remaining code words except for one of the same code words, Lt; / RTI > codebook.

The step of estimating the angle of incidence may estimate an estimated angle of incidence of a code word having a maximum value among the calculated correlation values as an angle of incidence of the received signal.

An apparatus for estimating a received signal angle of incidence according to an exemplary embodiment of the present invention includes a quantizer for quantizing a received signal received through multiple receive antennas using an analog-to-digital converter; A calculation unit for calculating a correlation value for each of the code words of the codebook generated in advance with respect to the quantized received signal and the estimated incident angle; And an estimator estimating an incident angle of the received signal based on the calculated correlation values.

The quantizer may 1-bit quantize the received signal using a 1-bit analog-to-digital converter.

Furthermore, an apparatus for estimating a received signal angle of incidence according to an exemplary embodiment of the present invention includes: a division unit for dividing a predetermined incidence angle range into a first section; And a generator for generating the codebook for the 1-bit quantized received signal using a code word for each of the divided first incident angular intervals, wherein the calculator calculates the code word of each of the generated codebooks And a correlation value for the 1-bit quantized received signal.

Furthermore, the apparatus for estimating a received signal angle of incidence according to an embodiment of the present invention includes: a division unit for dividing a predetermined incidence angle range into a first section; And generating a codebook for the 1-bit quantized received signal using the code word for each of the divided first incident angular intervals, and expanding the generated codebook by a predetermined number of times to generate an extended codebook And the calculation unit may calculate a correlation value for each of the code words of the extended codebook and the 1-bit quantized received signal.

The generator generates a second code word by excluding the remaining code words except for one of the same code words, if the same code words among the code words for each of the divided first incident angular intervals exist, The codebook can be generated.

The estimator may estimate an incident angle of a code word having a maximum value among the calculated correlation values as an incident angle of the received signal.

According to another aspect of the present invention, there is provided an apparatus for estimating a received signal angle of incidence in a multi-antenna system. An analog-to-digital converter for quantizing a reception signal received by the multiple reception antennas into a predetermined bit; And a base band processing unit for calculating a correlation value for each of the code words of the codebook generated in advance with respect to the quantized received signal and the estimated incident angle and estimating an incident angle of the received signal based on the calculated correlation values do.

According to embodiments of the present invention, it is possible to improve estimation accuracy of the angle of incidence of a received signal based on a codebook in a multi-receiving antenna system that has been subjected to 1-bit quantization.

In the present invention, a code word is generated for each incident angle within a range of values that an incident angle can have, a codebook is formed by collecting the code word, and a received signal is correlated with each code word, By estimating the angle as the incidence angle of the received signal, the complexity of the algorithm for estimating the incidence angle can be reduced.

That is, the present invention is versatile because it has a lower complexity than the minimum mean square error estimation that minimizes the mean square error, and since the codebook in the present invention can be predetermined according to the range of values that the incident angle can have, The complexity to make is also very low.

Furthermore, since the present invention has a small mean absolute error (MAE), the complexity is low and the accuracy of estimation can be improved.

In addition, since the present invention increases the number of times of reception in a fast fading channel, the estimation error of the incident angle can be further reduced, so that the present invention can be applied to a fast fading channel.

The present invention is also applicable to non-uniform and two-dimensional planar array antenna systems in the same manner.

1 shows a configuration of an embodiment of a multiple receive antenna system.
2 is a flowchart illustrating a method of estimating a received signal incident angle in a MIMO system according to an embodiment of the present invention.
FIG. 3 shows an example of a codebook before eliminating the same code word.
FIG. 4 shows an example of a codebook obtained after removing the same code word in FIG.
FIG. 5 is a graph illustrating an exemplary embodiment in which an average absolute error obtained by estimating the angle of incidence of a received signal according to an embodiment of the present invention is shown according to a signal-to-noise ratio.
FIG. 6 is a graph illustrating an exemplary embodiment in which an average absolute error occurring while estimating an incident angle from a signal received multiple times according to a signal-to-noise ratio according to an embodiment of the present invention.
FIG. 7 illustrates a configuration of an apparatus for estimating a received signal incident angle in a MIMO system according to an embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to or limited by the embodiments. In addition, the same reference numerals shown in the drawings denote the same members.

In general, an algorithm for estimating the angle of incidence in a line-of-sight uniformly linear array (ULA) multiple receive antenna system is well known. However, there is no conventional technique for estimating the angle of incidence from a received signal that has undergone 1-bit quantization instead of being a received signal.

Embodiments of the present invention are intended to improve the estimation accuracy while lowering the complexity by estimating the angle of incidence from a received signal that has been subjected to 1-bit quantization based on a codebook of low complexity.

In this case, the present invention can divide a range of values that the incident angle can have into a certain number of numbers, generate a code word for each incident angle, form a codebook by collecting the code word, and generate a codebook corresponding to a code word most similar to the received signal The angle can be found in the codebook and it can be estimated as the angle of incidence of the received signal.

In the present invention, the degree of resemblance between a received signal and a code word is determined as a value calculated by correlation. Here, the code word most resembling the received signal may mean a code word having the largest value among the calculated values after calculating the correlation with respect to each code word. That is, in the present invention, when the received signal is correlated with an arbitrary code word, when the value is maximized, the incident angle corresponding to the code word can be estimated as the actual incident angle.

Hereinafter, a method and an apparatus for estimating a received signal incident angle using embodiments of the present invention will be described.

1 shows a configuration of an embodiment of a multiple receive antenna system, which shows a configuration for a system in which N receive antennas are present and a receive antenna signal (received signal) is received via an RF chain and 1-bit ADCs will be.

1, the receiving unit includes a plurality of receiving antennas 110, an RF chain 120, a 1-bit ADCs 130, and a baseband processing unit 140.

The receive antenna 110 receives signals from the air and provides them to the RF chain 120 and the output signal of the RF chain 120 is quantized through the 1-bit ADCs 130.

Here, the RF chain 120 may be composed of various elements, and the RF chain 120 is a technical structure that is known to those skilled in the art, and a detailed description thereof will be omitted.

The 1-bit ADC 130 compares a signal output through the RF chain 120 with a preset threshold value for a magnitude of a received signal, and outputs a quantized value, for example, a value of +1 or -1.

Here, the 1-bit ADC 130 may include a 1-bit ADC for 1-bit quantizing the real part and an 1-bit ADC for 1-bit quantizing the imaginary part in the output signal of the RF chain 120.

The baseband processing unit 140 estimates the angle of incidence of the reception signal received by the reception antenna 110 based on the codebook using the 1-bit quantized reception signal output through the 1-bit ADCs 130.

Here, the baseband processing unit 140 is a means for estimating the incident angle of the received signal through the codebook-based algorithm of the present invention, and a detailed description thereof will be described with reference to FIG. 2 to FIG.

The method and apparatus according to the present invention in such a multiple receive antenna system will be described in detail with reference to Figs. 2 to 7.

Channel model

, 파장은

, 수신 신호는 입사 각도

로 수신되며,

N개의 다중 수신 안테나 사이의 거리는

d라고 가정하고 설명한다.A channel model assumed in the present invention will be described with reference to FIG. 1. In a channel having fading and noise, a line-of-sight (LoS) uniform linear array (ULA)

, The wavelength is

, The received signal is an incident angle

Lt; / RTI >

The distance between the N multiple receive antennas is

d.

는 페이딩

와 송신 신호x, 그리고 잡음

과 빛의 속도 c에 대해 아래 <수학식 1>과 같이 나타낼 수 있다.Received signal

Fading

The transmitted signal x, and the noise

And the speed of light c can be expressed by Equation (1) below.

[Equation 1]

Here, T may mean a transpose matrix.

에 대한 정보가 없다고 가정하면, 1비트 양자화를 거친 수신 신호

는 1-비트 ADC Q(·)에 대해 아래 <수학식 2>와 같이 나타낼 수 있다.The receiving end

Assuming that there is no information on the 1-bit quantized received signal,

Can be represented by Equation (2) below with respect to 1-bit ADC Q (·).

&Quot; (2) &quot;

Here, Q (·) may mean an analog-to-digital converter (ADC) that quantizes the real part and the imaginary part with 1 bit, respectively.

The Q (·) considered in the present invention can be expressed by Equation (3) below.

&Quot; (3) &quot;

는 복소수의 크기(Magnitude)와 위상(Phase)을 의미하고, mod는 나머지 연산자(Modulo Operator)를 의미할 수 있다.Here, r and

Denotes a magnitude and a phase of a complex number, and mod can denote a modulo operator.

The present invention intends to estimate the angle of incidence of the received signal in this channel model on the basis of a low-complexity codebook. Of course, the quantization method described above is one example, and the present invention is not limited to the quantization method described above, and can be applied to other quantization methods that can be used in the present invention.

2 is a flowchart illustrating a method of estimating a received signal incident angle in a MIMO system according to an embodiment of the present invention.

개의 구간으로 분할하고, 분할된

개의 입사 각도 구간 각각에 대한 코드워드를 이용하여 1-비트 양자화된 수신 신호의 코드북을 생성한다(S210, S220).Referring to FIG. 2, a method for estimating a received signal angle of incidence according to an embodiment of the present invention includes:

Divided into &lt; RTI ID = 0.0 &gt;

The codebook of the 1-bit quantized received signal is generated using the code word for each of the incident angle sections (S210, S220).

Here, in step S220, if the same code word among the code words for each incident angle section exists, the code book may be generated using the remaining code words except for the same code word.

The detailed description of steps S210 and S220 will be described using the code book items below.

Codebook

로 가정하면 입사 각도 범위 [l, u]를 미리 설정된 일정 개수 예를 들어,

개의 구간으로 나누거나 분할한다.A method of creating a codebook in the present invention is as follows. The range of possible incidence angles of the received signal is

, The incidence angle range [l, u] is set to a predetermined number, for example,

Divide or divide into two sections.

라고 정의하면 i번째 코드워드

는 아래 <수학식 4>와 같이 나타낼 수 있다.The representative value of the i-th section

, The i < th > codeword

Can be expressed as Equation (4) below.

&Quot; (4) &quot;

는

일 때의 배열 응답 벡터(Array Response Vector)가 1-비트 양자화를 거친 결과와 같다.In other words,

The

The array response vector is the same as the one-bit quantized result.

개의 구간으로 분할한다 가정하고 설명한다. 즉, i번째 구간은

이고,

는 구간의 중간 값인

로 정의할 수 있다.Hereinafter, in the detailed description of the present invention, it is assumed that the incident angle range [l, u]

Let us assume that we divide into two sections. That is, the i-th period

ego,

Is the median value of the interval

.

개의 코드워드가 만들어지고 동일한 코드워드가 존재한다면 동일한 코드워드 중 하나만 선택하여 코드북 C에 넣을 수 있다. 예를 들어, 만들어진 코드워드 중

은 동일한 코드워드가 없고,

가 동일한 코드워드 이며,

가 동일한 코드워드인 경우 코드북 C는

와 같이 만들 수 있다.At this time,

Code words are created and if the same code word exists, only one of the same code words can be selected and put in the codebook C. For example, of the codewords created

&Lt; / RTI &gt; does not have the same codeword,

Is the same codeword,

Is the same codeword, the codebook C

.

가 되며, c_i에 대응하는 값을

로 정의하면

에 대해

로 나타낼 수 있다.That is, for the i-th code word c _i of the codebook

And the value corresponding to c _i is

If you define

About

.

과 같은 방법으로도 만들 수 있지만 본 발명의 상세한 설명에서는 동일한 코드워드 중 중간에 있는 코드워드를 선택하여 코드북 C에 넣는 것으로 설명한다. 즉,

부터

까지 코드워드가 동일한 경우 코드북 C에 들어가는 코드워드는

가 될 수 있다. 여기서, floor(·)는 내림 함수(floor function)를 의미할 수 있다.Of course, the codebook C

However, in the detailed description of the present invention, it is described that a codeword in the middle of the same codeword is selected and put in the codeword C. In other words,

from

If the code words are the same, the code words entering the codebook C are

. Here, floor (·) may mean a floor function.

개의 코드워드 중 M(<

)개의 코드워드가 선택되면 코드북 C는 아래 <수학식 5>와 같이 나타낼 수 있다.By the method described above

Of the codewords M (<

) Code words are selected, the codebook C can be expressed as Equation (5) below.

&Quot; (5) &quot;

인 경우에 대한 코드북의 예를 나타낸 것이다. 도 3에서 동일한 색의 구간은 동일한 코드워드를 나타낸 것이며, 코드북을 생성하기 위한 조건인 l과 u는 실제 통신 시스템의 셀 세분화(Cell Sectorization)를 고려하여 결정될 수 있다.For example, FIG. 3 shows an example of a codebook before eliminating the same code word,

And the codebook for the case of FIG. In FIG. 3, a section of the same color represents the same codeword, and l and u, which are conditions for generating a codebook, can be determined in consideration of cell segmentation of an actual communication system.

개의 코드워드에서 동일한 코드워드들 중 하나의 코드워드만을 선택하여 만들어진 코드북 C는 도 4와 같이 나타나낼 수 있다. 즉, 도 3에 도시된 256개의 코드워드에서 동일한 코드워드들 중 하나의 코드워드만으로 만들어진 코드북 C는 64(M)개의 코드워드를 가질 수 있다.3

The codebook C generated by selecting only one code word among the same code words in the two code words can be represented as shown in FIG. That is, the codebook C made of only one of the same codewords in the 256 codewords shown in FIG. 3 can have 64 (M) codewords.

에 비해 작기 때문이다. 즉, 다중 수신 안테나의 수 N이 증가하면 수신단에서 수신 신호 입사 각도의 분해 능력이 증가하기 때문에 코드북 C의 코드워드 개수인 M이 줄어드는 것을 막을 수 있다.As can be seen from FIG. 4, as shown in FIG. 3, although there are 256 code words, the number of code words of the codebook C is reduced to 64, while the same code words are abundant. This is because the number N of multiple receive antennas

. That is, if the number N of the multiple receiving antennas increases, the resolving power of the angle of incidence of the received signal at the receiving end increases, thereby preventing the number M of codewords of the codebook C from decreasing.

Referring again to FIG. 2, if a codebook C of step S220 is generated through the above-described procedure and a signal is received through multiple receive antennas, the received signal is quantized using 1-bit ADCs, and 1-bit quantized And a correlation value for each of the code words of the codebook generated in step S220 are calculated (S230, S240).

When the correlation value of the 1-bit quantized received signal and the code word is calculated in step S240, the incident angle of the received signal is estimated based on the calculated correlation value (S250).

Here, the step S250 may estimate the incident angle corresponding to the code word having the largest value among the calculated correlation values as the incident angle of the received signal.

A detailed description of steps S230 to S250 will be described using the following algorithm items.

algorithm

에 대한 정보는 수신 신호 y 그 자체가 아닌 i번째 원소

에서 그 다음 원소

로 넘어갈 때 위상이 변하는 정도에 담겨 있다는 것을 알 수 있다. Ignoring the influence of noise and looking at the received signal y,

Is not the received signal y itself but the i-th element

The next element

It can be seen that the phase is shifted to the extent that it is shifted to.

와 x는 y의 각 원소들의 위상만 동일하게 회전시킬 뿐 y의 i번째 원소에서 그 다음 원소로 넘어갈 때 위상이 변하는 정도에 영향을 주지는 못하기 때문에 y로부터 입사 각도

를 추정하기 위해서는

와 x의 영향을 제거하고 y의 위상이 변하는 정도를 알아야 한다.In other words,

And x do not only affect the degree of phase change when they move from the i-th element to the next element of y, but rotate the phase of each element of y equally. Therefore,

To estimate

And remove the influence of x and know how much the phase of y changes.

에 잡음이 더해진 뒤 양자화를 거친

를 고려해야 하기 때문에 위의 결과를 이용하여 수신 신호의 입사 각도

를 추정할 때 발생하는 오차는 감안해야 한다.In the present invention, a 1-bit quantized received signal Q (y) rather than a received signal y is considered because it assumes a noisy channel and a 1-bit ADC. In other words,

After the noise is added,

It is necessary to take into consideration the angle of incidence of the received signal

The error that occurs when estimating the error rate should be considered.

와 x의 영향을 제거한 뒤 이를 이미 생성된 코드북의 코드워드 각각과 상관을 취해 코드워드 각각과의 상관 값을 계산하고, 계산된 상관 값들 중 가장 큰 값이 나오는 코드워드를 찾아 이에 해당하는

를 수신 신호의 입사 각도로 추정한다.The method according to the embodiment of the present invention is characterized in that the received signal Q (y)

And the correlation value of each code word is calculated by correlating each of the code words of the already generated codebook with the influence of x, and a code word having the largest value of the calculated correlation values is found,

Is estimated as the incident angle of the received signal.

와 같게 하기 위하여, Q(y)에

를 곱한 뒤 상관을 취하여 상관 값을 계산한다. 여기서, *는 공액 복소수(Complex Conjugate)를 의미한다.In other words, this is the first element of the first element of Q (y ₁₎ of Q (y) all c _i

Q (y) &lt; / RTI &gt;

And then the correlation value is calculated. Here, * denotes a complex conjugate.

이라 하면 추정 입사 각도

는 아래 <수학식 6>과 같이 나타낼 수 있다.The estimated incident angle of the received signal is

The estimated incidence angle

Can be expressed as Equation (6) below.

&Quot; (6) &quot;

Here, H denotes a conjugate transpose matrix.

개의 구간으로 나누거나 분할하여

개의 코드워드를 생성하고, 생성된

개의 코드워드로부터 M개의 코드워드를 가지는 코드북

를 생성한다.In other words, the method according to the present invention sets the predetermined incidence angle range [l, u] to a preset predetermined number, for example,

Divide or divide by

Code words are generated, and the generated

Codebooks having M code words from &lt; RTI ID = 0.0 &gt;

.

개의 코드워드로부터 중복된 코드워드를 제거한 M개의 코드워드를 선택함으로써, 생성될 수 있다.Here, the codebook C

Lt; / RTI &gt; code words from which the redundant code words have been removed from the code words.

를 수신 신호의 입사 각도로 추정한다.When a codebook C having M codewords is generated, a correlation value is calculated through correlation for each of the code words of the codebook C and the received signal Q (y) quantized by the 1-bit ADC, and the largest correlation value among the calculated correlation values Find the codeword with the value

Is estimated as the incident angle of the received signal.

를 신호 대 잡음비(SNR; Signal-to-Noise Ratio)에 따라 도시한 일 실시예 그래프를 나타낸 것으로, 입사 각도는

인 분포를 따르고, 다중 수신 안테나의 수 N=128, 코드북의 크기 M을 결정하는

=256, 다중 수신 안테나 사이의 거리

인 경우에 대한 일 예시도를 나타낸 것이다.FIG. 5 is a graph showing an average absolute error (MAE) obtained by estimating the angle of incidence of a received signal according to the method of the present invention.

(SNR) according to an embodiment of the present invention. The angle of incidence is represented by

, The number of multiple receive antennas N = 128, the size M of the codebook is determined

= 256, the distance between multiple receive antennas

In the case of FIG.

As shown in FIG. 5, the method proposed by the present invention shows that although the complexity is not high in the performance of estimating the incident angle, the incident angle estimation error becomes smaller as the signal-to-noise ratio increases. It can be seen that the algorithm of the present invention is very efficient in terms of complexity.

를 추정할 때 베이지안 추정(Bayesian Estimation), 즉 최대 우도 추정(Maximum Likelihood Estimation)이나 최소 평균 제곱 오차 추정을 사용했다면 복잡도는 기하급수적으로 커졌을 것이다. 왜냐하면 베이지안 추정은 복잡한 꼴의 피적분 함수를 최소 이중적분 내지는 삼중적분해야 하는 형태이기 때문이다. 이에 반해 본 발명에서 제안하는 방법은 수신된 신호를 코드북의 각 코드워드들과 상관을 취해 그 값들만 비교하면 되기 때문에 복잡도는 크지 않으면서 도 5를 통해, 성능 열화는 그리 크지 않다는 것을 알 수 있다.If the incidence angle

The complexity would have grown exponentially if Bayesian Estimation, ie Maximum Likelihood Estimation or Minimum Mean Square Error Estimation, was used. This is because Bayesian estimation is a form in which the integral function of a complex shape must be triple integrally or at least double. On the other hand, in the method proposed in the present invention, since the received signal is correlated with each codeword in the codebook and only the values are compared, the complexity is not large, but the performance deterioration is not significant .

와 잡음 n은 각각

과

인 분포를 따르고 송신 신호 x는

라고 가정한 것이며, ρ는 송신 신호의 전력을 의미한다. 송신 신호의 전력과 신호 대 잡음비는 대응적인 관계이기에, 도 5가 송신 신호 전력에 따른 그래프이지만, 신호 대 잡음비에 따른 그래프로 볼 수 있다.Then,

And noise n are

and

And the transmitted signal x is

, And p denotes the power of the transmission signal. Since the power of the transmission signal and the signal-to-noise ratio have a corresponding relationship, FIG. 5 is a graph according to the transmission signal power, but it can be seen as a graph according to the signal-to-noise ratio.

과 동일한데, 이는 수신 안테나의 수 N이

에 비해 작지 않기 때문에 발생한 결과일 수 있다.At this time, the size M of the codebook M = 256,

, Which means that the number N of receiving antennas is

Which is not so small as compared with the case of the first embodiment.

As can be seen from FIG. 5, the method according to the present invention finds that the average absolute error according to the signal-to-noise ratio is low, and thus the estimation accuracy of the incident angle can be improved. Of course, the method according to the present invention can improve the estimation accuracy of the incident angle of the received signal while reducing the complexity.

The method according to the present invention is based on the assumption that a signal is received once in a channel in which fading occurs. If the number of times of reception is increased in the fast fading channel and the signal is received L times in the fast fading channel, same.

An Extended Codebook-Based Algorithm: Channel Model

, 파장은

, 수신 신호는 입사 각도

로 수신되며, N개의 다중 수신 안테나 사이의 거리는d, 신호는 L번 수신된다 가정하고 설명한다.In a fast fading and noisy channel, LoS uniform linear array using multiple receive antennas, the frequency of the carrier is

, The wavelength is

, The received signal is an incident angle

, The distance between the N multiple reception antennas is d, and the signal is received L times.

와 기저 대역 송신 신호 x, 그리고 잡음

와 빛의 속도 c에 대해 아래 <수학식 7>과 같이 나타낼 수 있다.At this time, the i-th received signal y _i is fading

And the baseband transmission signal x, and noise

And the speed of light c can be expressed by Equation (7) below.

&Quot; (7) &quot;

Here, the received signal y received at L times can be expressed as Equation (8) below.

&Quot; (8) &quot;

는 시간 변수 i에 대해 서로 독립적이라 가정하고

도 서로 독립적이라 가정하며, 수신 신호의 입사 각도

는 긴 시간 단위로 변화하기 때문에 시간 변수에 상관없이 고정되어 있다고 가정할 수 있다.here

Are independent of each other for the time variable i

Are assumed to be independent from each other, and the incident angle

Can be assumed to be fixed regardless of the time variable since it changes in a long time unit.

Further, the i-th received signal y _i through the 1-bit quantization can be expressed as Equation (9) with respect to the 1-bit ADC Q (·).

&Quot; (9) &quot;

Using the above Equation (9), the received signal y which has been subjected to 1-bit patterning can be expressed as Equation (10) with respect to 1-bit ADC Q (·).

&Quot; (10) &quot;

Here, Q (·) may be an analog-to-digital converter (ADC) that quantizes the real part and the imaginary part respectively into 1 bit.

Extended Codebook-based Algorithm: Codebook

로 가정하면 입사 각도 범위 [l, u]를 미리 설정된 일정 개수 예를 들어,

개의 구간으로 나누거나 분할한다. 그리고, 상술한 코드북을 생성하는 과정에서 설명한 바와 같은 방법으로 동일한 코드워드를 없애는 과정을 통해 M개의 코드워드를 가지는 코드북

를 생성한다.A method of creating an extended codebook according to the present invention is as follows. The range of possible incidence angles of the received signal is

, The incidence angle range [l, u] is set to a predetermined number, for example,

Divide or divide into two sections. Then, through the process of eliminating the same codeword as described in the above-described process of generating the codebook, a codebook having M codewords

.

At this time, M in the extended codebook may be a value different from M in the codebook generated by the above-described one signal, and the value of M in the codebook may vary depending on the number of the same code word.

Here, the extended codebook C _L C L made after the time can be represented or defined as <Equation 11> below.

&Quot; (11) &quot;

Here, among the M codewords of C _L , the i-th codeword C _Li is the same as the structure in which C _i is made L times, which can be expressed by Equation (12) below.

&Quot; (12) &quot;

In this case, C may be an N x M matrix, and C _L may be an LN x M matrix.

Extended Codebook-Based Algorithm: Algorithm

와 x의 영향을 제거한 뒤 이를 이미 생성된 코드북 C_L의 코드워드 각각과 상관을 취해 코드워드 각각과의 상관 값을 계산하고, 계산된 상관 값들 중 가장 큰 값이 나오는 코드워드를 찾아 이에 해당하는

를 수신 신호의 입사 각도로 추정한다.A method according to another embodiment of the present invention is a method of receiving a 1-bit patterned reception signal Q (y), that is, Q (y) of Equation 10

And a correlation value between each of the code words by correlating each of the code words of the already generated codebook C _L with each other. Then, a code word having the largest value of the calculated correlation values is found,

Is estimated as the incident angle of the received signal.

, 추정 입사 각도를

이라 하면 추정 입사 각도

는 아래 <수학식 13>과 같이 나타낼 수 있다.That is, the extended codebook-based algorithm can also estimate the angle of incidence of the received signal by the method described in the codebook-based algorithm for one received signal,

, The estimated incidence angle

The estimated incidence angle

Can be expressed by Equation (13) below.

&Quot; (13) &quot;

개의 구간으로 나누거나 분할하여

개의 코드워드를 생성하고, 생성된

개의 코드워드로부터 M개의 코드워드를 가지는 코드북

를 생성한 후 코드북 C를 L번 이어 만든 확장된 코드북

을 생성한다.In other words, the method according to another embodiment of the present invention may set the predetermined incidence angle range [l, u] to a preset predetermined number, for example,

Divide or divide by

Code words are generated, and the generated

Codebooks having M code words from &lt; RTI ID = 0.0 &gt;

And then generates an extended codebook C

.

를 수신 신호의 입사 각도로 추정한다.When a codebook C _L having M codewords is generated, a correlation value is calculated through correlation with each of the code words of the codebook C _L and the received signal Q (y) quantized by the 1-bit ADC, Find the codeword with the largest value

Is estimated as the incident angle of the received signal.

를 신호 대 잡음비에 따라 도시한 일 실시예 그래프를 나타낸 것으로, 고속 페이딩 채널에서 수신 신호를 L번 수신하고, 입사 각도

는

인 분포를 따르며, 다중 수신 안테나의 수 N=128, 코드북의 크기 M을 결정하는

=256, 다중 수신 안테나 사이의 거리

인 경우에 대한 일 예시도를 나타낸 것이다.FIG. 6 shows an example of an average absolute error generated by estimating the angle of incidence from a signal received many times with the thus-

To-noise ratio, in which a received signal is received L times in a fast fading channel, and an incident angle &lt; RTI ID = 0.0 &gt;

The

, The number of multiple receive antennas N = 128, the size M of the codebook is determined

= 256, the distance between multiple receive antennas

In the case of FIG.

와 잡음

은

과

인 분포를 따르고, 송신 신호 x는

라고 가정한 것일 수 있다.Here, the size of the codebook is M = 256,

And noise

silver

and

, And the transmission signal x follows

.

As can be seen from FIG. 6, as the number L of received signals increases in the fast fading channel, the estimation error for the incident angle of the received signal decreases. That is, the method according to the present invention can be applied to a fast fading channel because the estimation error of the incident angle can be further reduced by increasing the number of times of reception in the fast fading channel.

As described above, the method according to embodiments of the present invention can improve estimation accuracy of the angle of incidence of a received signal based on a codebook in a multiple-receiving antenna system that has been subjected to 1-bit quantization.

The method according to the embodiments of the present invention creates a code word for each incident angle within a range of values that an incident angle can have, collects the code word to create a codebook, calculates a correlation between the received signal and each code word By estimating the angle corresponding to the largest value as the angle of incidence of the received signal, the complexity of the algorithm for estimating the angle of incidence can be reduced.

That is, the present invention is versatile because it has a lower complexity than the minimum mean square error estimation that minimizes the mean square error, and since the codebook in the present invention can be predetermined according to the range of values that the incident angle can have, The complexity to make is also very low.

Also, since the method according to the embodiments of the present invention has a small average absolute error (MAE), the complexity is low and the accuracy of estimation can be improved.

Also, the method according to embodiments of the present invention can be applied to a fast fading channel because it can further reduce the estimation error of the incident angle by increasing the number of reception in the fast fading channel.

However, the present invention is not limited to this. The codebook may be generated by quantizing the size of the received signal using a low-resolution ADC, It is also possible to estimate the incident angle of the received signal based on the correlation value between the word and the received signal quantized by the low resolution ADC.

FIG. 7 illustrates a configuration of an apparatus for estimating a received signal incident angle in a MIMO system according to an exemplary embodiment of the present invention. Referring to FIG. 7, there is shown a configuration of an apparatus for performing the method described with reference to FIGS.

7, an apparatus 700 according to the present invention includes a division unit 710, a generation unit 720, a quantization unit 730, a calculation unit 740, and an estimation unit 750. The quantization unit 730 may correspond to the configuration of the analog-to-digital conversion unit (ADC) shown in FIG. 1 and may include a division unit 710, a generation unit 720, a calculation unit 740, May correspond to the baseband processing unit shown in Fig.

개의 구간으로 분할한다.The division unit 710 divides the incident angle range previously set for the received signal into a first range,

.

Herein, the division unit 710 can divide the incident angle range at which the reception signal can be received in the multiple reception antenna system into a predetermined number of intervals, and can divide the division interval evenly.

개의 입사 각도 구간 각각에 대한 코드워드를 이용하여 1-비트 양자화된 수신 신호의 코드북을 생성한다.The generating unit 720 generates the divided

And generates a codebook of a 1-bit quantized received signal using code words for each of the incident angle sections.

개의 입사 각도 구간 각각에 대한 코드워드 중 동일한 코드워드를 제거한 일정 개수 예를 들어, M개의 코드워드를 포함하는 코드북을 생성할 수 있다.At this time, the generation unit 720 generates

For example, a codebook including M code words can be generated from the code words for each of the incident angular intervals, from which the same code word is removed.

The generator 720 may generate a codebook including M codewords for a 1-bit quantized received signal, and may further generate an extended codebook according to the number of receiving times by increasing the number of receiving times in a fast fading channel . Of course, the generator can generate the codebook from which the same code word is removed by removing the same code word even when generating the extended codebook.

The quantization unit 730 outputs a 1-bit quantized reception signal using a 1-bit ADC, that is, a signal received through multiple reception antennas.

At this time, the quantization unit 730 can quantize 1-bit quantized real and imaginary parts of the reception signal passed through the RF chain and output the 1-bit quantized signals.

The calculation unit 740 calculates the correlation value by correlating the 1-bit quantized received signal by the quantization unit 730 and the code word of the codebook already generated by the generation unit.

The estimator 750 estimates the angle of incidence of the received signal based on the correlation value of the 1-bit quantized received signal and the code word, respectively.

Here, the estimation unit 750 may estimate the incident angle corresponding to the code word having the largest value among the calculated correlation values as the incident angle of the received signal received by the multiple receive antennas.

It should be apparent to those skilled in the art that although the description of the received signal incident angle estimation apparatus of FIG. 7 is omitted, it may include all the contents described in FIGS. 2 to 6.

The system or apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the systems, devices, and components described in the embodiments may be implemented in various forms such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array ), A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to embodiments may be implemented in the form of a program instruction that may be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI &gt; or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (17)

Quantizing a received signal received through multiple receive antennas using an analog-to-digital converter;
Calculating a correlation value for each of the code words of the codebook generated in advance with respect to the quantized received signal and the estimated incident angle; And
Estimating an incident angle of the received signal based on the calculated correlation values
And estimating the angle of incidence of the received signal.
The method according to claim 1,
The quantizing step
Wherein the received signal is 1-bit quantized using a 1-bit analog-to-digital converter.
3. The method of claim 2,
Dividing a predetermined incidence angle range into a first section; And
Generating the codebook for the 1-bit quantized received signal using a code word for each of the divided first incident angular intervals;
Further comprising:
The step of calculating
And calculating a correlation value for each of the code words of the generated codebook and the 1-bit quantized received signal.
3. The method of claim 2,
Dividing a predetermined incidence angle range into a first section;
Generating a codebook for the 1-bit quantized received signal using a code word for each of the divided first incident angular intervals; And
Expanding the generated codebook by a predetermined number of times to generate an extended codebook
Further comprising:
The step of calculating
And calculating a correlation value for each of the code words of the extended codebook and the 1-bit quantized received signal.
The method of claim 3,
The step of generating the codebook
If there are the same code words among the code words for each of the divided first incident angular intervals, excluding the remaining code words except for one of the same code words, the code book including the second code word And generating the received signal.
The method according to claim 1,
The step of estimating the angle of incidence
And estimating an estimated angle of incidence for a code word having a maximum value among the calculated correlation values as an angle of incidence of the received signal.
A quantizer for quantizing a received signal received through multiple receive antennas using an analog-to-digital converter;
A calculation unit for calculating a correlation value for each of the code words of the codebook generated in advance with respect to the quantized received signal and the estimated incident angle; And
Estimating an incident angle of the received signal based on the calculated correlation values;
And a reception signal estimating unit for estimating a reception signal.
8. The method of claim 7,
The quantization unit
And the received signal is subjected to 1-bit quantization using a 1-bit analog-to-digital converter.
9. The method of claim 8,
A dividing unit dividing a predetermined incident angle range into a first section; And
And a generator for generating the codebook for the 1-bit quantized received signal using a code word for each of the divided first incident angular intervals,
Further comprising:
The calculation unit
And calculates a correlation value for each of the code words of the generated codebook and the 1-bit quantized received signal.
9. The method of claim 8,
A dividing unit dividing a predetermined incident angle range into a first section; And
Generates a codebook for the 1-bit quantized received signal using the code word for each of the divided first incident angular intervals, and generates the extended codebook by expanding the generated codebook by a predetermined number of times Generating unit
Further comprising:
The calculation unit
And calculating a correlation value for each of the code words of the extended codebook and the 1-bit quantized received signal.
10. The method of claim 9,
The generating unit
If there are the same code words among the code words for each of the divided first incident angular intervals, excluding the remaining code words except for one of the same code words, the code book including the second code word Wherein the reception signal angle estimator generates the reception signal incidence angle estimator.
8. The method of claim 7,
The estimation unit
And estimates an estimated incident angle for a code word having a maximum value among the calculated correlation values as an incident angle of the received signal.
An apparatus for estimating a received signal incident angle in a multi-antenna system,
Multiple receive antennas;
An analog-to-digital converter for quantizing a reception signal received by the multiple reception antennas into a predetermined bit; And
Calculating a correlation value for each of the code words of the codebook generated in advance with respect to the quantized received signal and the estimated incident angle, and estimating an incident angle of the received signal based on the calculated correlation values,
And a reception signal estimating unit for estimating a reception signal.
14. The method of claim 13,
The analog-to-
Wherein a 1-bit quantized value of the magnitude of the received signal is output using a 1-bit analog-to-digital converter (ADC).
15. The method of claim 14,
The baseband processor
Dividing a predetermined incidence angle range into a first section and generating the codebook for the 1-bit quantized received signal using a code word for each of the divided first incident angle sections, And calculating a correlation value for each of the code words of the codebook and the 1-bit quantized received signal.
15. The method of claim 14,
The baseband processor
Dividing a predetermined incidence angle range into a first section, generating a codebook for the 1-bit quantized received signal using a code word for each of the divided first incident angle sections, Is expanded by a preset number of reception times to generate an extended codebook, and a correlation value for each of the code words of the extended codebook and the 1-bit quantized received signal is calculated.
14. The method of claim 13,
The baseband processor
And estimates an estimated incident angle for a code word having a maximum value among the calculated correlation values as an incident angle of the received signal.

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