KR100919110B1 - Method for allocating sub-channels and estimating channels in order to estimate I/Q imbalances in uplink of wireless communication system - Google Patents

Abstract

The present invention relates to a subchannel allocation method and a channel estimation method for estimating an I / Q imbalance (In-Phase / Quadrature Imbalances) component in uplink of a wireless communication system, and more particularly to a subcarrier constituting a subchannel. The present invention relates to a subchannel allocation method and a channel estimation method capable of estimating an I / Q imbalance component generated in an uplink of a wireless communication system using a direct conversion scheme. To this end, the present invention provides a method for allocating a plurality of subcarriers as subchannels in a wireless communication system using at least one subchannel, the method comprising: generating a plurality of tiles including a first number of subcarriers selected from the plurality of subcarriers; And allocating at least one subchannel by tying tiles by a second number of the plurality of tiles, wherein the plurality of subcarriers existing in each subchannel are arranged symmetrically with each other. Provided are a subchannel allocation method for estimating an I / Q imbalance component in uplink.

Wibro, subchannel, tile, allocation method, uplink, subcarrier, I / Q imbalance

Description

Method for allocating sub-channels and estimating channels in order to estimate I / Q imbalances in uplink of wireless communication system}

The present invention relates to a subchannel allocation method and a channel estimation method for estimating I / Q imbalance (In-Phase / Quadrature-Phase Imbalances) generated in the uplink of a wireless communication system using a direct conversion method. In detail, the present invention relates to a subchannel allocation method and a channel estimation method capable of estimating an I / Q imbalance component in uplink of a wireless communication system by symmetrically arranging subcarriers allocated to subchannels.

Next-generation portable Internet service is a high-speed wireless Internet access anytime, anywhere, on the go. Mobile WIMAX (IEEE 802.16e) is in progress as an international standard for broadband wireless access system, and Wibro (Wireless Broadband Internet) system adopting orthogonal frequency division multiple access (OFDMA) is standardized for multiple access in Korea. .

WiBro uplink uses a direct-conversion scheme to implement a small low power RF terminal. However, the direct conversion method has some problems, one of which is the I / Q imbalance. I / Q imbalance occurs due to gain and phase mismatch mismatches between real and imaginary parts in the processing of baseband and RF signals. Since the IQ imbalance acts as mutual interference between symmetric subcarriers in the frequency domain, it causes performance degradation. Therefore, a process of estimating and compensating for this is necessary.

First, a method of improving the reception signal detection performance by suppressing the influence of an interference signal due to an I / Q imbalance component in the time domain and the frequency domain occurring at the RF stage of the receiver has been attempted. A method was attempted to solve the I / Q imbalance problem that occurred. However, even though these methods can suppress the influence of interference, there is a limit of performance improvement due to the power reduction of the corresponding subcarrier due to I / Q imbalance.

The loss of orthogonality between real and imaginary signals due to I / Q imbalance is a factor of performance degradation from the point of view of maintaining orthogonality. When passing through a multi-path fading channel, it is known that using a proper signal detection scheme can provide a better performance improvement than the absence of I / Q imbalance due to the frequency diversity gain effect.

Existing researches have been performed only for the OFDM scheme in which the user uses the entire band. Since this scheme knows each subcarrier that is symmetrical, it is generated in the transceiver using two consecutive preambles in the frequency domain using the Alamouti technique. I / Q imbalance can be estimated. However, in the OFDMA uplink in which the entire band is divided into several subchannels and used simultaneously by multiple users, even if an arbitrary subcarrier is assigned to one user, a subcarrier that is symmetrical to it is not allocated to the same user. It is impossible to estimate the I / Q imbalance component caused by mutual interference. This acts as interference between different subchannels, causing a problem of deterioration of performance and generation of an error floor that does not improve performance even at high SNR.

In order to solve the above problems, the present invention is to solve the performance degradation caused by the I / Q imbalance component by symmetrically arranging subcarriers present in the subchannel under the subchannel allocation scheme currently used in the uplink of a wireless communication system. Its purpose is to provide a new subchannel allocation method and channel estimation method.

In order to achieve the above object, the present invention relates to a method for allocating a plurality of subcarriers as subchannels in a wireless communication system using at least one subchannel, wherein a plurality of tiles including a first number of subcarriers selected from the plurality of subcarriers are selected. Generating; And allocating at least one subchannel by tying tiles by a second number of the plurality of tiles, wherein the plurality of subcarriers existing in each subchannel are arranged symmetrically with each other. Provided are a subchannel allocation method for estimating an I / Q imbalance component in uplink.

Allocating the subchannels includes symmetrically allocating the plurality of tiles; And assigning pilot subcarriers and data subcarriers included in the plurality of subcarriers to each tile.

Within each tile, the pilot subcarrier value and the negative conjugate value of the pilot subcarrier value are arranged to be symmetrical to each other at a diagonal position, wherein the first number is four and the second number is six.

In order to achieve the above object, the present invention provides a method for correcting the distortion of the sub-carrier value transmitted through the sub-channel in a wireless communication system using at least one sub-channel, receiving the sub-carrier transmitted through the sub-channel step; And estimating and correcting distortion of data subcarrier values included in the subcarriers using pilot subcarrier values included in the subcarriers, wherein the plurality of subcarriers existing in each subchannel are arranged symmetrically with each other. A method of correcting distortion of a subcarrier value transmitted through symmetrically arranged subcarriers in an uplink subchannel of a wireless communication system is provided.

The distortion of the data subcarrier value is estimated through linear interpolation of the pilot subcarrier value.

In order to achieve the above object, the present invention provides a device for allocating a plurality of subcarriers to a subchannel in a wireless communication system using at least one subchannel, the plurality of tiles comprising a first number of subcarriers selected from a plurality of subcarriers And a subchannel allocator for allocating at least one subchannel by binding tiles by a second number of the plurality of tiles, wherein the plurality of subcarriers existing in each subchannel are arranged symmetrically with each other. Provided is a subchannel allocation apparatus for estimating an I / Q imbalance component in uplink of a wireless communication system.

The subchannel allocator comprises: a tile allocator configured to symmetrically allocate the plurality of tiles; And

A pilot subcarrier assignment unit for allocating pilot subcarriers included in the plurality of subcarriers to each tile; And a data subcarrier allocator for allocating data subcarriers included in the plurality of subcarriers to each tile.

Within each tile, the pilot subcarrier assignment unit arranges the pilot subcarrier value and the negative conjugate value of the pilot subcarrier value to be symmetrical to each other at a diagonal position.

In order to achieve the above object, the present invention also provides a computer readable recording medium having recorded thereon a program for executing any one of the above methods.

In the case of estimating / compensating I / Q imbalance component by applying a new subchannel allocation method to the uplink of the wireless communication system according to the present invention, performance similar to that when the I / Q imbalance component does not exist can be obtained. It has an effect.

The terminology used in the present invention is a general term that is currently widely used as possible, but in certain cases, the term is arbitrarily selected by the applicant, in which case the meaning of the term is described in the detailed description of the invention. It should be understood that the present invention in terms of terms other than these terms.

Hereinafter, with reference to the accompanying drawings a preferred embodiment of the present invention that can specifically realize the above object, the present invention is not limited or limited by the above embodiments.

1 is a block diagram showing a transmitter structure of a wireless communication system according to an embodiment of the present invention. Referring to FIG. 1, a wireless communication system according to the present invention includes a Wibro (Wireless Broadband) system using an OFDMA scheme, and is not limited to the Wibro system but may be applied to other communication systems. The transmitter includes a subchannel allocator 100, a serial / parallel converter 200, a pilot symbol inserter 300, an inverse fast fourier transform (IFFT) 400, a parallel / serial converter 500, and a guard interval. Insertion unit 600, D / A conversion unit 700, RF processing unit 800 is included.

The subchannel allocator 100 receives a coded signal and allocates a subchannel. A method of allocating subchannels will be described later with reference to FIGS. 4 to 7. The serial / parallel converter 200 receives serial modulation symbols assigned with the subchannels and the bands output from the subchannel allocator 100 and converts the serial modulation symbols into parallel signals. The pilot symbol inserting unit 300 inserts pilot symbols into a parallel signal.

The IFFT 400 performs an N-point IFFT on a signal having a pilot symbol inserted therein, and the parallel / serial converter 500 converts a signal on which the IFFT is performed into a serial signal. The guard interval inserting part 600 inserts a guard interval signal into the serial signal. When the guard interval signal is transmitted in an OFDMA communication system, the guard interval signal is inserted to remove interference between a previous OFDM symbol transmitted at a previous OFDM symbol time and a current OFDM symbol transmitted at a current OFDM symbol time.

 The D / A converter 700 converts the serial signal into which the guard interval signal is inserted into an analog signal, and the RF processor 800 RF-processes the analog signal to be transmitted in the air. It is transmitted to a wireless network through a transmitting antenna.

2 is a detailed block diagram of a subchannel allocation unit according to an embodiment of the present invention. Referring to FIG. 2, the subchannel allocator 100 includes a tile allocator 110, a pilot subcarrier allocator 120, and a data subcarrier allocator 130.

The tile allocator 110 generates a plurality of tiles by selecting a specific number of subcarriers (hereinafter, referred to as a “first number”) among a plurality of subcarriers and generates a plurality of tiles. Subchannels are generated by tile-by-tile tiles). For example, four of the 210 subcarriers may be selected to generate tiles, and six tiles may be bundled to generate one subchannel. The structure of the tile will be described later with reference to FIG. 4.

The pilot subcarrier assignment unit 120 allocates a pilot subcarrier to the tile. In a subchannel allocation method and apparatus for estimating an I / Q imbalance component in uplink of a wireless communication system according to the present invention, the pilot subcarriers are symmetrically allocated to each other on a subchannel. A method of allocating pilot subcarriers will be described later with reference to FIG. 7. The data carrier allocation unit 130 allocates a data carrier to the tile.

3 is a block diagram illustrating a receiver structure of a wireless communication system according to an embodiment of the present invention. Referring to FIG. 3, the receiver includes an RF processor 900, an A / D converter 1000, a guard interval remover 1100, a serial / parallel converter 1200, an FFT 1300, and channel estimation and compensation. Part 1400 is included.

Since the components of the receiver are the same as or similar to those of the transmitter shown in FIG. 1 except for the channel estimation and compensation unit 1400, those skilled in the art can easily understand the function of each component, Omit.

The channel estimation and compensation unit 1400 estimates a distortion component combined with I / Q imbalance and radio channel characteristics by using the received pilot subcarrier, and applies the distortion component to the received data subcarrier to obtain desired data. . The method of estimating the distortion component and applying it to the subcarrier will be described later with reference to FIG. 8.

Hereinafter, for convenience of description, a subchannel allocation method for estimating an I / Q imbalance component in an uplink of a wireless communication system according to the present invention will be described using the Wibro system as an example.

4 shows a tile structure used in the Wibro uplink subchannel. Wibro uplink supports 35 subchannels for PUSC (Partial Usage of Subchannels) permutation, and several transmitters are allocated to one or more subchannels. At this time, one subchannel is composed of six tiles, wherein one tile is a basic allocation unit that is formed to form a subchannel by collecting four adjacent subcarriers within three consecutive symbol intervals and forming a block.

The frequency band used is divided into a total of 210 tiles, and grouping 35 adjacent tiles to form 6 groups. One subchannel is created by selecting one tile from these six groups in the manner specified in the standard.

5 shows a subchannel allocation process according to an embodiment of the present invention. A method of allocating subchannels by tying a second number of tiles in the plurality of tiles shown in FIG. 5 is used in a conventional Wibro system. Although the method of allocating subchannels is used, the method of configuring subchannels is different. A subchannel allocation method according to the present invention will be described later with reference to FIG.

The conventional subchannel allocation scheme prevents symmetric subcarriers from being assigned to one user, and thus, when the I / Q imbalance occurs, the I / Q imbalance cannot be estimated. If the Wibro uplink transceiver uses both direct conversion schemes at the RF end, I / Q imbalance will be present at both transceivers. In the transceiver of the OFDMA system, the I / Q imbalance model can first model the I / Q imbalance generated in the transceiver and then model the I / Q imbalance of the entire system simultaneously with the effect of the channel.

는 아래의 수학식1 및 수학식2와 같이 표현될 수 있다.6 is an equivalent model of a baseband system combining a frequency selective fading channel and transmit / receive I / Q imbalance. Signal in time domain distorted by transmit I / Q imbalance component in FIG.

May be expressed as Equation 1 and Equation 2 below.

와

는 송신기에서의 이득 및 위상 불균형 성분을 나타내고,

는 I/Q 불균형이 발생하지 않은

의 공액 복소수 신호를 나타낸다. 이후, 송신 RF 단에서 왜곡된 송신신호

는 주파수 선택적 페이딩 채널

를 통과한 후,

의 형태로 수신되며, 아래의 수학식3으로 표현될 수 있다.In Equation 2

Wow

Denotes the gain and phase imbalance component at the transmitter,

I / Q imbalance did not occur

Represents a conjugate complex signal. Thereafter, the distorted transmission signal in the transmitting RF stage

Is a frequency selective fading channel

After passing through

It is received in the form of, and can be represented by Equation 3 below.

평균이 0, 분산이

인 복소 백색 부가 잡음 (AWGN Additive White Gaussian Noise)을 나타내고,

는 채널 임펄스 응답,

는 컨벌루션 기호를 나타낸다. 여기서 수신 신호

는 송신기에서와 같이 직접변환에 의한 왜곡이 발생하게 되고 이를 시간영역에서 표현하면 아래의 수학식4 및 수학식5와 같다.In equation (3)

Mean is 0, variance is

AWGN Additive White Gaussian Noise,

Channel impulse response,

Represents a convolutional symbol. Where received signal

Distortion occurs by direct conversion as in the transmitter, and this is expressed in Equations 4 and 5 below.

와

는 수신기에서의 왜곡 성분을 나타내고,

와

는 각각 수신기에서의 이득 및 위상 불균형 값을 나타낸다. 수학식4를 주파수 영역의 신호로 표현하기 위해 FFT를 적용하면 아래의 수학식6과 같다.In Equation 4 and Equation 5

Wow

Denotes the distortion component at the receiver,

Wow

Are the gain and phase imbalance values at the receiver, respectively. If the FFT is applied to express Equation 4 as a signal in the frequency domain, Equation 6 below.

는 OFDM 심볼 내의 부반송파 인덱스,

은 전체 부반송파 수,

는

를 의미한다. 수학식4에서 FFT는 입력신호를 주기신호로 간주하므로

번째 부반송파와

번째 부반송파는 서로 간에 간섭으로 작용한다.In Equation 6

Is the subcarrier index in the OFDM symbol,

Is the total number of subcarriers,

Is

Means. In Equation 4, the FFT regards the input signal as a periodic signal.

The first subcarrier

The subcarriers act as interferences between each other.

Now, by combining Equation 1, Equation 3 and Equation 4, and using the determinant of Equation 6, the effect of I / Q imbalance of the entire system can be expressed as a determinant in the frequency domain as shown in Equation 7a. .

Here, each component in Equation 7a may be represented by the following equations.

,

,

,

는 각각 주파수 영역에서의 왜곡을 겪은 수신신호 행렬, 채널과 결합된 송수신 왜곡 성분 행렬, 송신신호 행렬 그리고 수신기에서 I/Q 불균형에 의해 왜곡된 잡음 성분 행렬을 나타낸다.

은

≤

,

≤

으로 서로 다른 사용자를 나타내고,

은 WiBro 상향링크를 사용하는 전체 사용자 수를 나타낸다. I/Q불균형으로 인한 영향은 아래의 수학식8a 및 수학식8b에서 확인할 수 있다.In the above equations

,

,

,

Denotes a received signal matrix that has undergone distortion in the frequency domain, a transmit / receive distortion component matrix coupled to the channel, a transmit signal matrix, and a noise component matrix distorted by I / Q imbalance at the receiver.

silver

≤

,

≤

Indicates different users,

Represents the total number of users using WiBro uplink. The effects of the I / Q imbalance can be seen in Equations 8a and 8b below.

In order to examine the desired reception signal, Equation 7a may be rearranged so as to be expressed as Equations 8a and 8b below.

Here, each component of Equations 8a and 8b may be represented by the following equations.

사용자의

번째 수신 부반송파 데이터는

사용자의

번째 부반송파 데이터에 의해

만큼 간섭이 발생하게 된다. 기존의 OFDM 방식과 같이, 전 대역을 한 사용자가 사용하여

와

번째 부반송파 모두를 알고 있다면, 두 부반송파와 Alamouti 기법이 적용된 연속된 2개의 프리엠블을 이용하여 왜곡 행렬의 성분

를 모두 추정할 수 있다. In an OFDMA system, if an I / Q imbalance occurs, as shown in Equation 8a,

Of your

The first received subcarrier data

Of your

By the first subcarrier data

As long as the interference occurs. As with the conventional OFDM method, the entire band is used by a user

Wow

If both subcarriers are known, the components of the distortion matrix are composed of two subcarriers and two consecutive preambles using the Alamouti technique.

We can estimate all of them.

사용자의

번째 부반송파에 파일럿이 실 려도

번째 부반송파는

이라는 다른 사용자에게 할당되므로 I/Q 불균형으로 발생한 왜곡 행렬을 추정할 수 없게 된다. 이는 곧 부채널간 간섭으로 작용하여, 심각한 성능 열화 및 에러 플로어 현상을 초래할 수 있다.However, as described above, in an OFDMA system in which an entire band is divided into several subchannels and assigned to multiple users,

Of your

Even if a pilot is loaded on the first subcarrier

The first subcarrier is

Is assigned to another user, we cannot estimate the distortion matrix resulting from the I / Q imbalance. This soon acts as interchannel interference, which can lead to severe performance degradation and error floors.

In order to estimate the I / Q imbalance occurring in the Wibro uplink, six tiles constituting the subchannel are paired in a symmetrical position in pairs, and the pilot carriers located in the tile must also exist in the symmetrical position. To this end, the present invention can estimate the I / Q imbalance component by arranging subcarriers existing in one subchannel symmetrically with different tile allocation methods constituting the subchannel.

만 그대로 사용하고, 나머지 3개의 타일은 아래의 수학식9a, 수학식9b 및 수학식9c과 같이 할당하여 6개의 타일이 각각 대칭이 되어 하나의 부채널을 생성한다.In order to estimate the I / Q imbalance component in Equation 7a, the limited tile allocation method is based on using the existing allocation method as it is, but the upper three tiles of the six tiles generated

Only the three tiles are used as they are, and the remaining three tiles are allocated as shown in Equations 9a, 9b, and 9c below, and six tiles are symmetrical to generate one subchannel.

를 추정할 수 있다. 즉, 상기 수학식9a, 수학식9b 및 수학식9c를 이용하여 타일을 할당한 후에, 파일럿 부반송파를 서로 대칭되도록 할당하고, 데이터 부반송파를 할당한다. 도 7에서

번째 부반송파와

번째 부반송파가 대칭되며,

번째 부반송파와

번째 부반송파가 서로 대칭되게 배치된다. 이때, 파일럿 부반송파는 부채널 상에서 서도 대각선으로 대칭된다. 즉, 파일럿 부반송파 값과 상기 파일럿 부반송파의 음의 공액 값이 대각선 위치에 배치된다. 예를 들면, 도 7에서

파일럿 부반송파와

의 음의 공액 값(

)이 서 로 대각선 위치에서 배치됨을 알 수 있다. 7 illustrates a new tile allocation method according to an embodiment of the present invention. Referring to FIG. 7, when the tiles allocated to one subchannel are symmetrical, and the pilot using the Alamouti technique is used, the distortion matrix is conventionally used.

Can be estimated. That is, after allocating tiles using Equations 9a, 9b, and 9c, the pilot subcarriers are assigned to be symmetrical to each other, and the data subcarriers are allocated. In Figure 7

The first subcarrier

The first subcarrier is symmetrical,

The first subcarrier

The subcarriers are arranged symmetrically with each other. At this time, the pilot subcarriers are also diagonally symmetrical on the subchannel. That is, a pilot subcarrier value and a negative conjugate value of the pilot subcarrier are disposed at a diagonal position. For example, in FIG.

Pilot subcarriers

Negative conjugate of (

You can see that) are arranged in diagonal positions with each other.

8 illustrates a method of estimating a distortion value due to I / Q imbalance according to an embodiment of the present invention. The tile structure and pilot allocated to one subchannel in the Wibro uplink may be expressed as Equation 9d below.

와

는 첫 번째 심볼에 존재하는 서로 대칭된 위치에 있는 파일럿 신호이고,

와

는 2X2 정칙행렬을 만들기 위해 Alamouti 구조가 적용된 3번째 심볼에 존재하는 대칭된 위치에 있는 파일럿 신호를 나타낸다.In Equation 9d

Wow

Are pilot signals in symmetrical positions with each other in the first symbol,

Wow

Denotes the pilot signal at the symmetrical position present in the 3rd symbol with the Alamouti structure applied to create a 2x2 regular matrix.

The pilot of the first symbol and the pilot of the third symbol are distorted and received by the frequency characteristics of the channel and the transmission / reception I / Q imbalance, and can be represented by Equations 9e and 9f below.

와

는 각각 수신된 첫 번째 심볼의 파일럿과 세 번째 심볼의 파일럿 신호를 주파수 영역에서 나타낸 것이다. 3 심볼 구간 동안 채널의 특성이 동일하게 유지되므로 위의 두 식을 결합하고 수학식7a을 이용하여 왜곡된 파일럿 신호를 아래의 수학식9g과 같이 나타낼 수 있다.here

Wow

Denotes a pilot signal of the first symbol and a pilot signal of the third symbol in the frequency domain, respectively. Since the characteristics of the channel remain the same during the three symbol periods, the above two equations may be combined and the distorted pilot signal may be expressed as Equation 9g using Equation 7a.

를 이용하여 왜곡행렬

를 아래의 수학식9h과 같이 추정할 수 있다.Using the pilot signal that the receiver knows

Using Distortion Matrix

Can be estimated as in Equation 9h below.

의 파일럿 부반송파 위치의 왜곡행렬 값을 추정할 수 있다. 이를 이용하여 나머지 데이터 부반송파의 왜곡행렬 값 추정은 선형 보간법을 이용하여 아래의 수학식들과 같이 계산될 수 있다.If the above process is repeated for six tiles forming one subchannel, as shown in FIG.

The distortion matrix value of the pilot subcarrier position of may be estimated. Estimation of the distortion matrix values of the remaining data subcarriers using the linear interpolation method may be calculated using the following equations.

는

와

를 동시에 통과하게 된다. 그러므로 적당한 수신기 알고리즘을 적용할 경우, 다이버시티 이득을 얻을 수 있으며 기존의 간섭억제 기법에 비해 성능을 향상 시킬 수 있다.When a new tile allocation scheme is applied to a subchannel, when I / Q imbalance occurs in the transceiver from Equation 7a, spreading occurs between symmetric subcarriers, thereby transmitting a signal.

Is

Wow

Will pass simultaneously. Therefore, if the proper receiver algorithm is applied, diversity gain can be obtained and performance can be improved compared to the conventional interference suppression technique.

는 I/Q 불균형에 의한 간섭 신호를 아래의 수학식10과 같이 등화 과정을 통해 복구 할 수 있다.Transmission signal

Can recover an interference signal due to I / Q imbalance through an equalization process as shown in Equation 10 below.

는 ZF(Zero Forcing)을 수행하기 위한 행렬이고,

는 추정된 왜곡행렬,

는 역행렬을 나타낸다. ZF기법으로 수신 신호를 검출 할 경우, I/Q 불균형이 없는 경우의 수신 성능에는 근접하지만, I/Q 불균형으로부터 다이버시티 이득을 획득 할 수 없다.Where equalization matrix

Is a matrix for performing zero forcing (ZF),

Is the estimated distortion matrix,

Denotes the inverse of the matrix. When the received signal is detected by the ZF technique, the reception performance without the I / Q imbalance is close, but the diversity gain cannot be obtained from the I / Q imbalance.

를 이용하여, 아래의 수학식11로 표현되는 ML(Maximum Likelihood) 검출 방식을 통하여 수신 신호를 검출 할 수 있다.Estimated distortion matrix

By using, it is possible to detect the received signal through the ML (Maximum Likelihood) detection method represented by Equation 11 below.

This ML detection method can provide optimal performance and obtain diversity gain in an environment having I / Q imbalance and frequency selective characteristics. However, as the modulation order increases, the amount of computation increases exponentially, making it difficult to implement in higher order modulation.

Diversity gain can be obtained by ML technique, but it is difficult to implement due to increase of operation amount according to modulation order. Therefore, received signal can be detected by OSIC technique which reduces performance complexity and performance close to ML.

의 각 원소가 달라지며, 채널 계수

와

에 따른 SNR 차가 발생하므로 V-BLAST에서 송신 신호 검출을 위해 사용하는 OSIC 방식을 적용 할 수 있다.I / Q imbalance introduces a non-uniform spread between two symmetric subcarriers, resulting in a channel matrix

Each element of is different, and the channel coefficient

Wow

As the SNR difference occurs, the OSIC method used for V-BLAST for transmission signal detection can be applied.

9 is a graph showing the effect of performance improvement when using the sub-channel allocation method according to an embodiment of the present invention. 9 shows performance when I / Q imbalance occurs in the Wibro uplink when the subchannel is configured by the existing tile allocation method and the subchannel is configured by the new tile allocation method to estimate and compensate for the I / Q imbalance. To compare, we show the result of comparing the compensation of the channel using the existing tile allocation method with no I / Q imbalance.

는 3.1절에서 제안한 새로운 부채널 할당 기법을 적용한 파일럿을 이용하여 추정하였으며, 도 9에서 "No IQ Imbalances"는 I/Q불균형 성분이 존재 하지 않을 때의 통상적인 수신기에서의 채널 추정 성능을 나타낸 것이고, "IQ Imbalances/ZF", "IQ Imbalances/ML", "IQ Imbalances/OSIC"는 본 발명에 따른 새로운 타일 할당 방식을 적용하였을 때, 각각의 수신 신호 검출 기법 하에서의 성능을 나타낸 것이다. 마지막으로 "IQ Imbalances/Conventional"은 I/Q 불균형이 존재할 때, 기존의 타일 할당 방식에서의 I/Q 불균형 성분을 고려하지 않은 통상적인 수신기 성능을 나타낸 것이다.Distortion Matrix to Compensate for Distorted Received Signals

Is estimated using a pilot using the new subchannel allocation scheme proposed in Section 3.1. In FIG. 9, "No IQ Imbalances" shows channel estimation performance in a typical receiver when no I / Q imbalance component is present. , "IQ Imbalances / ZF", "IQ Imbalances / ML", and "IQ Imbalances / OSIC" show performance under each received signal detection technique when the new tile allocation method according to the present invention is applied. Finally, "IQ Imbalances / Conventional" shows typical receiver performance without considering the I / Q imbalance component in the existing tile allocation scheme when I / Q imbalance exists.

When I / Q imbalance occurs in the transceiver in the Wibro uplink, since the I / Q imbalance component cannot be estimated in the conventional tile allocation method, as shown in FIG. When applying the new tile allocation method according to the present invention, the performance detected by the ZF method is almost the same as the performance without the IQ imbalance.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments. However, various modifications and variations can be made by those skilled in the art to which the present invention pertains.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and all the things that are equivalent to or equivalent to the claims as well as the following claims will belong to the scope of the present invention. .

1 is a block diagram showing a transmitter structure of a wireless communication system according to an embodiment of the present invention.

2 is a detailed block diagram of a subchannel allocation unit according to an embodiment of the present invention.

3 is a block diagram showing a receiver structure of a wireless communication system according to an embodiment of the present invention.

4 illustrates a tile structure used in a Wibro uplink subchannel

5 is a diagram illustrating a subchannel allocation process according to an embodiment of the present invention.

6 is a block diagram illustrating an equivalent model of a baseband system combining a frequency selective fading channel and a transmit / receive I / Q imbalance.

7 illustrates a new tile allocation method according to an embodiment of the present invention.

8 is a diagram illustrating a method of estimating a distortion value due to I / Q imbalance according to an embodiment of the present invention

9 is a graph showing the effect of the performance improvement when using the sub-channel allocation method according to an embodiment of the present invention

<Description of the symbols for the main parts of the drawings>

100: sub-channel allocation unit 110: tile allocation unit

120: pilot carrier allocation unit 130: data carrier carrier allocation unit

200: serial / parallel conversion unit 300: pilot symbol insertion unit

400: IFFT 500: Parallel / Serial Conversion

600: protection section insertion part 700: D / A conversion part

800, 900: RF processor 1000: A / D converter

1100: protection section removal unit 1200: serial / parallel conversion unit

1300: FFT 1400: Channel Estimation and Compensation Section

Claims (13)

A method for allocating a plurality of subcarriers as subchannels in a wireless communication system using at least one subchannel, Generating a plurality of tiles including a first number of subcarriers selected from the plurality of subcarriers; And Allocating at least one subchannel by tying tiles by a second number of the plurality of tiles; A plurality of subcarriers present in each of the subchannels in which the tiles are bundled by the second number are each one of a first subcarrier to an Nth subcarrier included in one subchannel, and the K th subcarrier is symmetric with the NK-1 subcarrier. Subchannel allocation method in the uplink of the wireless communication system, characterized in that arranged to be. 2. The method of claim 1, wherein allocating the subchannels Allocating the plurality of tiles such that the K-th tile is symmetrical with the M-K-1 tile among the first to Mth tiles included in one subchannel; Allocating each pilot subcarrier included in the first to Mth tiles symmetrically so that a pilot subcarrier included in the K-th tile is symmetric with a pilot subcarrier included in the M-K-1 tile; And Allocating data subcarriers included in the plurality of subcarriers; and a subchannel allocation method in an uplink of a wireless communication system. The method of claim 2, The plurality of tiles are allocated to the sub-channel in the uplink of the wireless communication system, characterized in that assigned using the following equation (1). [Equation 1]

The method of claim 2, A pilot subcarrier included in the MK-1 tile symmetrical to a pilot subcarrier included in the K-th tile among the first to Mth tiles included in the one subchannel is a pilot subcarrier included in the K-th tile. The subchannel allocation method in the uplink of a wireless communication system, characterized in that it has a negative conjugate value of. The method of claim 1, And wherein the first number is four and the second number is six. A method of correcting distortion of a subcarrier value transmitted through the subchannel in a wireless communication system using at least one subchannel, Receiving a subcarrier transmitted through a subchannel; And Estimating and correcting a distortion of data subcarrier values included in the subcarriers through linear interpolation of pilot subcarrier values included in the subcarriers; The plurality of subcarriers present in the subchannels are symmetric in the wireless communication system, wherein among the first subcarriers to the Nth subcarriers included in the subchannels, the Kth subcarrier is arranged to be symmetrical with the NK-1 subcarriers. A method for correcting distortion of subcarrier values transmitted through subchannels that are arranged in such a way. delete An apparatus for allocating a plurality of subcarriers as subchannels in a wireless communication system using at least one subchannel, A subchannel allocator configured to generate a plurality of tiles including a first number of subcarriers selected from a plurality of subcarriers, and allocate at least one subchannel by grouping tiles by a second number of the plurality of tiles. A plurality of subcarriers present in each of the subchannels in which the tiles are bundled by the second number are each one of a first subcarrier to an Nth subcarrier included in one subchannel, and the K th subcarrier is symmetric with the NK-1 subcarrier. Subchannel allocation apparatus of a radio communication system uplink, characterized in that arranged to be. The method of claim 8, wherein the subchannel allocation unit A tile allocator for allocating the plurality of tiles such that the K-th tile is symmetrical with the M-K-1 tile among the first to Mth tiles included in one subchannel; A pilot subcarrier assignment unit for symmetrically assigning each pilot subcarrier included in the first to Mth tiles so that a pilot subcarrier included in the K-th tile is symmetrical with a pilot subcarrier included in the M-K-1 tile; And And a data subcarrier allocator for allocating data subcarriers included in the plurality of subcarriers to each tile. The method of claim 9, The tile allocator assigns the plurality of tiles to each other by using Equation 1 below. [Equation 1]

The method of claim 9, The pilot subcarrier assignment unit may include a pilot subcarrier included in the MK-1 tile symmetrical to a pilot subcarrier included in the K-th tile among the first to Mth tiles included in the one subchannel. And a pilot subcarrier included in each of the first tile to the M-th tile so as to have a negative conjugate value of the pilot subcarrier included in the tile. The method of claim 8, And wherein the first number is four and the second number is six. A computer-readable recording medium having recorded thereon a program for executing the method according to any one of claims 1 to 6.

Images