KR101670452B1 - Impedance noise robust loading method in load modulating communication system - Google Patents

Abstract

According to the present invention, in a load impedance control in a multi-antenna communication system, when a load modulation transmitter is implemented using a single RF line, an optimum load impedance value capable of generating a signal robustly to the load impedance noise can be obtained.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for adjusting a load impedance in a multi-antenna communication system,

The present invention relates to a multi-antenna communication system, and more particularly, to a multi-antenna communication system capable of generating a signal robust to load impedance noise when a load modulation transmitter is implemented using a single RF line. To a load impedance adjustment method in a multi-antenna communication system that allows a load impedance value to be obtained.

In general, a MIMO system is a technology for transmitting signals by installing two or more antennas in a transmitter and a receiver of a communication system. Since different signals can be transmitted in the same band for each antenna, Of the system.

Meanwhile, in the conventional communication system, a transceiver is constructed by configuring several antennas and several RF lines in order to implement the MIMO (multiple input multiple output) system. For example, to configure a 4x4 MIMO system, a communication system may be configured using four or more antennas and four RF lines.

At this time, each RF line is provided with a modem for modulating / demodulating a signal, a high-performance digital-to-analog converter (DAC) for converting a digital signal into an analog signal, An oscillator for generating a carrier frequency, an amplifier for amplifying a signal, and the like.

Since the RF line uses various devices, the RF line is bulky and expensive. Especially, in N × N MIMO systems, as N increases, the number of RF lines increases, which increases the price and size of the transceiver.

1 shows a MIMO configuration scheme in a conventional communication system. 1, a signal s (t) transmitted in a conventional communication system can be represented by a phaser having a size and an orientation as shown in the following equations (1) and (2) , And these phasors are represented by two independent parameters s1 and s2. That is, two independent parameters are controlled in one RF to generate a signal, which is then added back to the antenna. Therefore, N RFs are required to transmit N signals.

One conventional method to overcome this disadvantage is to place multiple parasitic antennas around one active antenna to adjust the load impedance of each parasitic antenna so that N signals An antenna system using a single RF for transmission is proposed.

FIG. 2 shows a schematic configuration of a single RF MIMO communication system using the conventional load impedance adjustment described above.

In the conventional system as shown in FIG. 2, when the active antenna and the parasitic antenna are disposed at a close distance, mutual coupling is generated. Therefore, the parasitic antenna is transmitted through a mutual coupling matrix The current flowing through each antenna is controlled by adjusting the load impedance applied to the tick antenna.

In addition, by improving the way of reliance on the unstable mutual coupling relation, each antenna is isolated, power is supplied by one amplifier (AMP), and a constant voltage is applied to each antenna using an impedance matching circuit And a loading modulator is provided in each antenna to control the current.

Meanwhile, in the above case, the impedance to be loaded on each antenna should be composed of a lossless element to increase the antenna power efficiency. However, since it can not generate a signal with a real value when it is composed only of a Rossley element, it is configured as a two port network composed of three loading elements.

은 수식 4와 같이 2 포트 네트워크의 3개의 변수에 의해 결정된다(

이기 때문에). 이처럼 2 포트 네트워크를 이용해 전류를 제어하게 되면 만들고자 하는 신호에 대해서 여러 조합의 3개의 변수 세트(set)가 존재하게 된다. 따라서 원하는 신호를 만들기 위해 단순히 랜던 세트(random set)를 선택하게 되면 잡음에 매우 취약한 어드미턴스 세트 또는 임피던스 세트가 선택되어 버릴 수 있다는 문제점이 있다.In this case, if the relationship between the voltage and the current in each antenna is represented by an admittance, it is as shown in FIG. 3 and [Equation 3]. And the current signal to be controlled

Is determined by the three parameters of the two-port network as shown in equation (4)

). When controlling the current using a two-port network, there are three sets of variables for the signal to be generated. Therefore, if a random set is simply selected to generate a desired signal, an admittance set or an impedance set which is very susceptible to noise may be selected.

Korean Registered Patent No. 10-0981571 (registered on September 03, 2010)

Accordingly, in the present invention, when a load modulation transmitter is implemented using a single RF line, a load impedance adjustment method is proposed in a multi-antenna communication system in which an optimum load impedance value capable of generating a signal robustly to a load impedance noise can be obtained do.

In addition, we propose a method to determine the load impedance value that minimizes the real - time resistance noise value in determining the load impedance value in order to make the desired signal in the impedance loading system composed of the Rossless 2 port network.

A method of adjusting a load impedance in a multi-antenna communication system, the method comprising: calculating a first input impedance of an mth modulator connected to an mth antenna; calculating a first input impedance of a mth modulator connected to an mth antenna; The method comprising the steps of: retrieving a set of impedance matrices most resistant to noise having a positive real component; constructing a second input impedance with the sought impedance matrix set; And determining it as an impedance.

The searching may further include calculating a first impedance value of the Mth modulator corresponding to the noise of the first input impedance, calculating a second impedance value not including the noise And examining an impedance matrix set such that the positive real component of the second impedance value among the plurality of impedance matrices constituting the first impedance value is the largest.

Further, in the testing step, each impedance parameter in the impedance matrix set is included in a predetermined impedance value range.

The impedance matrix may be a combination of a plurality of impedance parameters corresponding to a plurality of loseless elements.

The impedance value range is from -500 ohms to +500 ohms.

According to the present invention, in the adjustment of the load impedance in a multi-antenna communication system, when the load modulation transmitter is implemented using a single RF line, an advantage that an optimal load impedance value capable of generating a signal robustly to the load impedance noise can be obtained .

In addition, an impedance loading system composed of a Rossless 2 port network has an advantage in that it can obtain a load impedance value that minimizes the real-time resistance noise value in setting the load impedance value in order to make a desired signal.

값에 따른

의 실수 성분 그래프 예시도,
도 7은 본 발명의 실시예에 따른

값에 따른

의 실수 성분과 잡음 비율 그래프 예시도,
도 8은 본 발명의 실시예에 따른 각각의 임피던스 매트릭스에 따른 에러 크기 그래프 예시도.FIG. 1 is a block diagram of an antenna system for configuring MIMO in a conventional communication system;
2 is a block diagram of a conventional load modulating transmitter,
3 is a diagram illustrating a two-port network model for performing admittance loading,
4 illustrates an exemplary 2-port network model for impedance loading according to an embodiment of the present invention,
5 is a flowchart of a load impedance adjustment process according to an embodiment of the present invention,
Figure 6 is a block diagram of an embodiment of the present invention

Depending on the value

An example of a real component graph of Fig.
Figure 7 is a block diagram of an embodiment of the present invention

Depending on the value

A graph of real component and noise ratio graph of FIG.
8 is an exemplary graph of error magnitudes according to each impedance matrix in accordance with an embodiment of the present invention.

Hereinafter, the operation principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions of the present invention, and these may be changed according to the intention of the user, the operator, or the like. Therefore, the definition should be based on the contents throughout this specification.

The present invention considers two-port impedance loading rather than admittance as in FIG. 4 and (5).

의 세트(set) 중 포지티브 리얼 성분(positive real component)을 갖는 잡음(noise)에 가장 강인한 세트를 찾는다. 로스리스 구성요소(Lossless element)로만 구성된 시스템이라 하더라고 실제 구현에 있어서 이상적인 로스리스 시스템을 기대하기는 어렵기 때문에 회로 선로, 요소(element)의 저항 등에 의해서 예상보다 포지티브한 저항(resistor) 성분이 있을 것이란 것을 예상할 수 있다. 본 시스템이 적용되는 것이 신호제어인 만큼 이러한 잡음을 최대한 줄이는 방안이 필요하다. Also, in the present invention, the impedance matrices of the m-th load modulator (400)

A set that is most robust to noise having a positive real component is searched. Although it is difficult to expect an ideal rossless system in actual implementation even if it is a system composed only of a lossless element, there is a more positive resistor component than expected due to the resistance of the circuit line and the element Can be expected. Since this system is applied to the signal control, it is necessary to reduce the noise as much as possible.

5 shows a flow of the load impedance adjustment process according to the embodiment of the present invention. The load impedance control process flow may be calculated and applied by a separate computer device or may be calculated by a load modulator determination device (not shown) connected between the matching circuit and the load modulator in the antenna system configuration of FIG. 4, Modulator 400 as shown in FIG.

Hereinafter, the flow of the load impedance adjustment process of the present invention will be described in detail with reference to FIG.

을 산출한다(S500). 이때, 포지티브 리얼 잡음(Positive real noise)이 발생했을 때의 m번째 로드 모듈레이터(load modulator)의 입력 임피던스(input impedance),

은 아래의 [수학식 6]과 같이 표현되며, 발생한 포지티브 리얼 잡음(positive real noise)

은

에 더해진 형태로 나타난다고 할 수 있다. 이와 같은 특성을 이용하여 포지티브 리얼 잡음에 강한 임피던스 매트릭스(impedance matrix)를 찾을 수 있다.First, the input impedance of the m-th load modulator 400

(S500). In this case, the input impedance of the m-th load modulator when positive real noise occurs,

Is expressed as Equation (6) below, and the generated positive real noise is expressed by Equation (6)

silver

In the form of a combination of the two. Using these characteristics, we can find an impedance matrix that is strong against positive real noise.

는 아래의 [수학식 7]과 같이

와

로 구성된 형태로 바꾸어 표현할 수 있다.At this time, the component constituting the impedance matrix

Is expressed by Equation (7) below

Wow

As shown in Fig.

,

)를 산출한다(S502). 이때 포지티브 리얼 잡음을 포함하지 않는 m번째 로드 모듈레이터(400)의 출력(output) 전류

과 포지티브 리얼 잡음을 포함하는 m번째 로드 모듈레이터(400)의 출력 전류

은 아래의 [수학식 8]처럼

와 포지티브 리얼 잡음이 존재하지 않을 경우의 m번째 로드 모듈레이터(400)의 입력 임피던스

로 표현 가능하다(S504).Next, the output current of the Mth load modulator

,

(S502). At this time, the output current of the m-th rod modulator 400, which does not include positive real noise,

And the output current of the mth load modulator 400 including the positive real noise

Is expressed by Equation (8) below

And the input impedance of the m-th load modulator 400 when there is no positive real noise

(S504).

을 만들 수 있는 임피던스 매트릭스는 수없이 많은데 그 중 포지티브 리얼 잡음의 영향을 가장 적게 받는 임피던스 매트릭스를 찾아내고자 한다. 잡음에 의한 왜곡을 가장 최소화 할 수 있는 방법은

의 리얼 성분(real component)이 가장 크도록 하는 것인데 이를 만족하는 최적의 임피던스 매트릭스(optimal impedance matrix)는 아래의 [수학식 9]에서와 같이 optimization problem을 통해 찾을 수 있다. As can be inferred from equation (8) above, one

There are a number of impedance matrices that can be made, and we want to find an impedance matrix that is least affected by positive real noise. A way to minimize noise distortion

The optimal impedance matrix satisfying this condition can be found through an optimization problem as shown in Equation (9) below. ≪ EMI ID = 9.0 >

항을 [수학식 7]을 이용해서

와

으로 이루어진 관계식으로 치환하면 [수학식 10]처럼

와

으로만 표현된다.

을

에 대해서 정리하면 [수학식 10]과 같은 결과가 나온다. 따라서 [수학식 11]처럼

의 실수부를

로 나타낼 수 있다. 즉, [수학식 9]의 optimization 문제가

라는 1개의 변수로 이루어진 함수로 표현되었다. In the above constraint 1 of Equation 9,

(7) < RTI ID = 0.0 >

Wow

(10) as shown in Equation (10)

Wow

.

of

, The result is as shown in Equation (10). Therefore, as in Equation (11)

The real part of

. That is, the optimization problem of [Equation 9]

As a function of one variable.

로 미분한 결과이다. [수학식 13]에서 [수학식 12]의 값이 0이 되도록 하는 값

를 찾는다(S506).

와 [수학식 11]의 제약조건 1에 따라 variable

의 양 끝 값인 ㅁ500 중 [수학식 11]의 objective function을 최대화하는 값이 optimization problem의 optimal solution

가 된다(S508). 이때, variable

값은 예를 들어 -500오옴∼+500오옴으로 설정될 수 있으나, 이에 한정되는 것은 아니다.Equation (12) represents the objective function of Equation (11)

. In Equation (13), a value such that the value of [Equation (12)] becomes 0

(S506).

And the constraint 1 of Equation (11)

The optimal value of the objective function of Equation (11) among the ㅁ 500 values at the both ends of the optimization solution

(S508). At this time, variable

The value may be set to, for example, -500 ohms to +500 ohms, but is not limited thereto.

Next, the load impedance of the mth load modulator is configured with the impedance matrix selected as described above (S510).

값에 대하여

에 따른 리얼 성분 값의 변화를 확인할 수 있으며 [수학식 11]의 솔루션(solution)인 최적의 임피던스 매트릭스를 찾을 수 있다. 도 7에서 optimal problem을 통해 찾아낸 솔루션에서 포지티브 리얼 잡음에 대한

의 리얼 성분 값이 가장 큰 것을 보아 [수학식 11]을 통해 찾아낸 임피던스 매트릭스가 포지티브 리얼 잡음에 가장 강인한 것을 확인할 수 있다.6,

About the value

And the optimal impedance matrix, which is a solution of Equation (11), can be found. In Figure 7, the solution found through the optimal problem is that for positive real noise

It can be seen that the impedance matrix found through Equation (11) is most robust to the positive real noise.

중 하나의 (

)에 대하여 앞서 설명한 optimal한 임피던스 매트릭스

를 사용한 경우와 랜덤하게 고른 두 가지 임피던스 매트릭스

와

를 사용한 경우 각각의 출력 전류의 에러(error)를 도 8에서 비교하였다. The output currents of the three m-th rod modulators 400 used in Figs. 6 and 7

One of the (

The optimal impedance matrix < RTI ID = 0.0 >

And two randomly selected impedance matrices

Wow

The error of each output current is compared in FIG.

의 범위 내에서 포지티브 리얼 잡음의 영향을 받아 나타나는 출력 전류의 평균 에러값을 도 8에서 확인할 수 있다. 제안한 최적화 방법을 통해 선택된 임피던스 매트릭스를 이용하는 경우 전류 신호값에서 확연히 적은 에러가 발생하는 것을 확인할 수 있다.Also, according to the constraint 1 of [Equation 9], variable

The average error value of the output current which is affected by the positive real noise within the range of " 0 " If the selected impedance matrix is used through the proposed optimization method, it can be confirmed that a considerably small error occurs in the current signal value.

As described above, according to the present invention, in a load impedance control in a multi-antenna communication system, when a load modulation transmitter is implemented using a single RF line, an optimum load impedance value capable of generating a signal robustly to a load impedance noise Can be obtained. Also, to determine the load impedance value to make the desired signal in an impedance loading system consisting of a Rossless 2 port network, the load impedance value that minimizes the signal-to-real-value resistance noise value can be obtained.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should not be limited by the described embodiments but should be defined by the appended claims.

400: m-th load modulator

Claims (7)

A method of adjusting a load impedance in a multi-antenna communication system,
calculating a first input impedance of an mth modulator connected to the mth antenna,
Searching for a set of impedance matrices most resistant to noise having a positive real component among the plurality of impedance matrices constituting the first input impedance,
Configuring a second input impedance with the searched impedance matrix set;
And determining the second input impedance as the load impedance of the mth antenna,
Wherein the searching comprises:
Calculating a first impedance value of the m-th modulator corresponding to the noise of the first input impedance,
Calculating a second impedance value that does not include the noise;
Inspecting a set of impedance matrices such that the positive real component of the second impedance value among the plurality of impedance matrices constituting the first impedance value is largest
And adjusting the impedance of the load.
delete The method according to claim 1,
In the inspecting step,
Wherein each impedance parameter in the impedance matrix set is included in a predetermined impedance value range.
The method according to claim 1,
Wherein the impedance matrix comprises:
And a plurality of impedance parameters corresponding to a plurality of loseless elements.
The method of claim 3,
The impedance value range may be,
Wherein the load impedance is adjusted to -500 ohms to +500 ohms.
The method according to claim 1,
The m < th >
And a two-port network.
The method according to claim 1,
The first input impedance of the m-th modulator (

),
Wherein the load impedance is calculated according to the following equation.
[Mathematical Expression]

: Positive real noise,

: Input impedance of the mth modulator without noise

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