KR100821921B1 - Inter carrier interference removing algorithm for ofdm system using the repetition coding or deep fade detection - Google Patents

Abstract

A method for removing an ICI(Inter Carrier Interference) in an OFDM(Orthogonal Frequency Division Multiplexing) system using a repetition coding or deep fade detection is provided to improve a performance of a communication system and a broadcasting system by selectively adapting a repetition coding or deep fade detection algorithm to a conventional time domain ICI removing algorithm. A method for removing an ICI in an OFDM(Orthogonal Frequency Division Multiplexing) system using a repetition coding or deep fade detection includes the steps of: copying NS data symbols into M groups of data symbols and generating group symbols for a base band symbol to be assigned and transmitted to a different sub carrier(S210); generating a mapping group symbol by mapping each symbol of the group symbols to the sub carrier(S220); performing an inverse discrete Fourier transform, insertion of a CP(Cyclic Prefix) for the mapping group symbol, and transmitting the mapping group symbol to a receiver(S230); removing the CP of the mapping group symbol and performing a discrete Fourier transform(S240); extracting the group symbols, which are demapped from the sub carrier, from the mapping group symbol(S250); adapting an MRC(Maximum Ratio Combining) to the group symbol(S260); and generating a base band symbol by adapting a time domain ICI removing algorithm to the group symbol using the MRC(S270).

Description

INTER CARRIER INTERFERENCE REMOVING ALGORITHM FOR OFDM SYSTEM USING THE REPETITION CODING OR DEEP FADE DETECTION}

Figure 1 is an experimental diagram showing the error that appears after the application of the Time Domain ICI removal algorithm according to the prior art.

2 is a conceptual diagram illustrating a procedure of a Time Domain ICI removal algorithm.

3 is a conceptual diagram illustrating a procedure of applying a repetition coding algorithm and a time domain ICI removal algorithm according to a first embodiment of the present invention.

Figure 4 is an experimental diagram showing the BER performance of the Repetition Coding based Time Domain ICI removal algorithm.

5 is a conceptual diagram showing an application procedure of a Time Domain ICI removal algorithm based on Deep Fade Detection according to a second embodiment of the present invention.

The present invention relates to a method for eliminating inter-contiguous interference (ICI) that occurs during high-speed movement of a moving object in an OFDM system. The present invention relates to an ICI cancellation method of an OFDM transmission / reception system using a repetition coding and deep fade detection algorithm.

Recently, an orthogonal frequency division multiplexing (OFDM) -based transmission system has been selected and commercialized by various standardization standards. In particular, OFDM-based systems are being actively researched as a multiple access method of next-generation 4G cellular systems. One of the disadvantages of the OFDM-based system is that when the mobile moves at a high speed, inter-channel interference (hereinafter referred to as "ICI") occurs and performance of the system is degraded. The present invention proposes an ICI removal algorithm using repetition coding or deep-fade detection to overcome the disadvantages of the proposed time-domain ICI removal scheme. The repeting coding and deep detection techniques described above are described in the references below.

[1] David Tse and Pramod Viswanath, Fundamentals of Wireless Communication, Cambridge University Press, 2005.

[2] Shaoping Chen and Tianren Yao, "An inter-carrier interference suppression scheme for OFDM systems in time-varying fading channels," ISCAS'04, vol. 3, pp. 337-340, May 2004.

[3] T. Seki, M. Itami, H. Ohta, and K. Itoh, "A study of OFDM system applying frequency diversity," PIMRC, vol. 2, pp. 1385-1389, Sept. 2000.

1 is an experimental diagram illustrating an error that appears even after application of a time domain ICI removal algorithm according to the prior art when deep fade occurs in a single path fading channel (left) and a self-path fading channel (right), and FIG. 2 is a time domain. A conceptual diagram showing the sequence of the ICI elimination algorithm.

1 and 2, as an OFDM system model according to the related art, a channel impulse response (CIR) of a channel during one OFDM symbol period may be expressed by Equation 1 below.

_l,n는 l번째 경로의 n번째 시간에서의 복소 채널이득으로 Jakes 전력 스펙트럼을 갖는 WSSUS(Wide-Sense Stationary Uncorrelated Scattering) 협대역 복소 Gaussian 과정이고, τ_l은 샘플링 간격으로 정규화된 해당 경로의 시간지연이다. L은 페이딩 경로의 총 수를 나타낸다. 복소 채널이득은 다시 평균값과 평균값에 대한 변화량으로 나타낼 수 있으며, 각각 수학식 2와 수학식 3과 같다. here,

_{l, n} is a Wide-Sense Stationary Uncorrelated Scattering (WSSUS) narrowband complex Gaussian process with Jakes power spectrum with complex channel gain at the nth time of the lth path, and τ _l is the time of the path normalized to the sampling interval. It's a delay. L represents the total number of fading paths. The complex channel gain may be expressed as an average value and a change amount with respect to the average value, and are represented by Equations 2 and 3, respectively.

Assuming that the receiver synchronization and channel estimation are perfect, the OFDM received signal in the time domain can be developed using the above two equations as shown in Equation 4 below.

은 N에 의한 modulo 연산을 나타낸다. 수학식 4에 대한 DFT(Discrete Fourier Transform)를 구하면 아래의 수학식 5와 같다.here,

Denotes a modulo operation by N. The Discrete Fourier Transform (DFT) for Equation 4 is obtained as Equation 5 below.

Here, when the first component and the second component of Equation 5 are developed, they may be expressed as Equations 6 and 7 below.

, here

,

,

,

으로 정의한다.

It is defined as

Meanwhile, when the received signal is expressed in the frequency domain by using the above Equations 5 to 7 for the calculation of the conventional Time Domain ICI elimination algorithm, it can be expressed as Equation 8 below.

을 추정하고, 1-탭 등화기로 보상하면, 아래의 수학식 9와 같이 나타낼 수 있으며, 이 심볼을 HD(Hard Decision)에 의해 검출하면 아래의 수학식 10과 같이 나타낼 수 있다. In other words, the channel estimation algorithm estimated

When the equation is estimated and compensated with the 1-tap equalizer, it can be represented by Equation 9 below. When the symbol is detected by HD (Hard Decision), it can be expressed by Equation 10 below.

Where f _{dec , HD} (x) is an arbitrary function that performs HD. The detection signal obtained through Equation 10 is taken as an Inverse Discrete Fourier Transform (hereinafter referred to as "IDFT") to be a time domain signal, and can be represented by Equation 11 below through a channel estimation algorithm.

를 추정하고 수학식 11의 신호와 컨볼류션(convolution)을 취하게 되면 수학식 12와 같은 수신신호를 재생 성할 수 있다. Here, by arbitrary channel estimation algorithm

By estimating and convolution with the signal of Equation 11, a received signal as shown in Equation 12 can be regenerated.

When the regenerated signal value is subtracted from the originally received signal through Equation 11, it may be expressed as Equation 13 below.

If DFT is again performed, Equation 14 from which ICI is removed can be obtained.

과 같이 ICI 성분을 줄여주게 된다.The existing time domain ICI algorithm repeatedly performs the process of Equations 8 to 14,

This reduces the ICI component.

의 값이 deep fade 에 빠져서 작은 값이 될 경우, 수학식 9 및 수학식 10의 과정에서 잘못된 데이터를 검출하게 되어 ICI가 제거되지 않는 문제점이 발생한다. The problem of the conventional scheme is that when a deep fade occurs in a single path fading channel and a multipath fading channel, as shown in FIG. 1, a large number of errors occur even if ICI is removed by the conventional scheme. That is,

If the value of F is reduced to the deep fade and becomes a small value, bad data is detected in the processes of Equations 9 and 10, and thus, ICI is not removed.

An object of the present invention is to solve the above problems, it is possible to remove the inter-channel interference (ICI) by using the Repetition Coding technique or Deep Fade Detrction technique, ICI can be removed even in the channel where the deep-fade occurs The present invention provides a method for removing ICI of an orthogonal frequency division multiplexing system using repetition coding and deep fade detection.

In order to achieve the above object, the ICI removal method of the orthogonal frequency division multiplexing system using Repetition Coding according to the first embodiment of the present invention,

An interference cancellation method between adjacent channels in an OFDM transmission / reception system applying a repetition coding method to a time domain scheme. In order to transmit the same baseband symbol to different subcarriers, N _s data symbols {c _j | 0 Copying ≤ j ≤ N _s -1} into M groups to generate group symbols {c _{i , j} | 0 ≦ _j ≦ M−1,0 ≦ _j ≦ _s −1}; A second step of mapping each symbol of the group symbols to a subcarrier to generate a mapping group symbol {X _k | 0 ≦ _k ≦ N−1}; A third step of transmitting the mapping group symbol to a receiver through IDFT processing and CP insertion; A fourth step of removing a CP of the mapping group symbol by the receiver and performing a DFT process; A fifth step of extracting the unmapped group symbol from the subcarrier from the CP removal and DFT-processed mapping group symbol; Applying a MRC to the group symbol; And generating a baseband symbol by applying the time domain ICI removal algorithm to the group symbols to which the MRC is applied.

를 이용하는 것을 특징으로 한다.In addition, the second step, a function for generating the mapping group symbol

It characterized by using.

In addition, f _map (i, j) of the above function is an arbitrary function of assigning the j-th symbol of the i-th group to the k-th subcarrier.

를 이용하는 것을 특징으로 한다.In addition, the fifth step may be a function for extracting the group symbols from the mapping group symbols.

It characterized by using.

In addition, f _demap (k) is an inverse function of f _map used in a transmitter as an arbitrary function of allocating a symbol mapped to a k th subcarrier to a j th symbol of an i th group.

는

로 변형되는 것을 특징으로 한다.

Is

Characterized in that the deformation.

In addition, the sixth step, the group symbol is a function for applying the MRC

Characterized by satisfying.

In addition, in order to transmit the same baseband symbol to the subcarrier to increase the modulation index of the transmission signal in order to prevent the degradation of the spectral efficiency is characterized in that the transmission.

In addition, in order to transmit by increasing the modulation index, it is characterized by increasing the QPSK modulation to 16QAM or 64QAM.

In addition, an ICI cancellation method of an orthogonal frequency division multiplexing system using deep fade detection according to a second embodiment of the present invention is a method of canceling interference between adjacent channels in an OFDM transmission / reception system using the deep fade detection method.

A first step in which a baseband symbol is modulated and transmitted at a transmitter; Receiving a modulated baseband symbol at a receiver to obtain an SNR for detecting a deep fade; Obtaining a channel estimate H _{m , m} using an LS channel estimation algorithm; A fourth step of determining the M-th detected baseband symbol as a deep fade generation symbol and excluding the data symbol when the H _{m , m} value of an Mth subcarrier falls below 1 / SNR; And a fifth step of applying a time domain ICI removal algorithm to data symbols except for the deep fade generation symbol.

In addition, the H _{m , m} and SNR,

을 만족시키는 것을 특징으로 한다.Equation

It is characterized by satisfying.

In addition, the SNR is,

를 통해 얻어지는 것을 특징으로 한다.Equation

Characterized in that obtained through.

In order to achieve the above object, the ICI removal method of an orthogonal frequency division multiplexing system using Repetition Coding and Deep fade Detection according to the third embodiment of the present invention, OFDM applied Repetition Coding and Deep Fade Detection technique to Time Domain technique. A method for canceling interference between adjacent channels in a transmission / reception system of a system, in which a transmitter transmits N _s data symbols {c _j | 0 ≦ _j ≦ N _s −1} to allocate and transmit the same baseband symbol to different subcarriers. A first step of generating group symbols {c _{i, j} | 0 ≦ _j ≦ M−1,0 ≦ _j ≦ N _s −1} by copying into M groups; Generating a mapping group symbol {X _k | 0 ≦ _k ≦ N−1} in which each symbol among the group symbols is mapped to a subcarrier; A third step of transmitting the mapping group symbol to a receiver through IDFT processing and CP insertion; A fourth step of removing a CP of the mapping group symbol by the receiver and performing a DFT process; A fifth step of extracting the unmapped group symbol from the subcarrier from the CP removal and DFT-processed mapping group symbol; Obtaining a SNR to receive the group symbol and detect a deep fade; A seventh step of obtaining H _{m, m} which is a channel estimate value using the LS channel estimation algorithm; An eighth step of determining the Mth detected group symbol as a deep fade generating symbol and excluding the corresponding group symbol when the H _{m, m} value of an Mth subcarrier falls below 1 / SNR; And a ninth step of applying a time domain ICI removal algorithm to a group symbol except the deep fade generation symbol.

Hereinafter, an ICI removal method of an orthogonal frequency division multiplexing system using repetition coding and deep fade detection according to an embodiment of the present invention will be described in detail.

The present invention proposes two algorithms to compensate for the shortcomings of the existing time-domain ICI removal algorithm. That is, the receiver first applies a repetition coding algorithm in which the same symbol is allocated to different subcarriers and transmits the same symbol at the transmitter, and then detects the occurrence of the deep fade in the receiver. Repetition coding in the second embodiment of applying the existing time domain ICI elimination algorithm after applying the deep fade detection algorithm using only reliable data by excluding the data of the corresponding subcarrier position from the ICI elimination algorithm A description will be given of the third embodiment in which the algorithm and the deep fade detection algorithm are combined.

The above and other objects and features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a conceptual diagram illustrating a sequence of applying a repetition coding algorithm and a time domain ICI removal algorithm according to a first embodiment of the present invention, and FIG. 4 is an experimental diagram illustrating BER performance of a time domain ICI removal algorithm based on repetition coding. to be.

Referring to FIGS. 3 and 4, the repetition coding scheme refers to transmitting the same symbol to different subcarriers by the transmitter. The receiver detects the same symbol transmitted through different subcarriers by MRC (Maximum Ratio Combining) to obtain frequency diversity gain. At this time, in order to compensate for the disadvantage that the spectral efficiency is lowered by sending the same symbol, the modulation index of the transmission signal is increased. For example, when repetition coding is performed on a signal transmitted by QPSK, it is transmitted by 16QAM or 64QAM. Copy N _s data symbols {c _j | 0≤j≤N _s -1} into M groups and copy the group symbols {c _{i, j} | 0≤j≤M-1,0≤j≤N _s -1} To generate (S210). This group symbol is allocated to a corresponding subcarrier by a subcarrier mapper (S220). M represents the number of groups, and each group is composed of N _s data symbols. Since M and N _s are variables that depend on how to configure subcarriers of an OFDM system, it is not appropriate to limit them to specific values. However, if illustrated the values through a preferred embodiment, when that the total number of data sub-carriers of the OFDM symbol N = 1024, if divided by it into two groups, and the M = 2, data symbol number of each group, N _s = 512 Becomes Equation 15 for obtaining this assigned symbol {X _k | 0 ≦ _k ≦ N−1} may be expressed as follows. Where k is the index of symbol X _k .

Here, f _map (i, j) is an arbitrary function for assigning the j th symbol of the i th group to the k th subcarrier. The function k = f _map (i, j) is for performing X _k = c _{i, j} (i-th group, j-th symbol c _{i, j} to X _k ), which is within the scope of the present invention. It can be implemented in various forms by those skilled in the art to limit to a particular form is not suitable. However, to illustrate this function in a preferred embodiment, the mapping function may be expressed as k = N _s xi + j. The range of i and j is (0 ≦ i ≦ M−1, 0 ≦ j ≦ N _s −1). If M = 2 and N _s = 512, and i = 0, j = 1, then k = 1. These symbols are then transmitted after undergoing IDFT (Inverse Discrete Fourier Transform) processing and CP (Cyclic Prefix) insertion (S230). The receiver removes the CP and performs DFT processing (S240). A reception group symbol is obtained by the subcarrier demapper as shown in Equation 16 below.

Here, f _demap (k) is an inverse process of f _map used by the transmitter as an arbitrary function of allocating a symbol mapped to the k th subcarrier to the j th symbol of the i th group (S250). Since the function (i, j) = f _demap (k) is the inverse of k = f _map (i, j), it is not desirable to limit it to a specific form for the foregoing reasons. However, to illustrate this function through the preferred embodiment, it is assumed that the mapping function k = f _map (i, j) is k = N _s xi + j as described above. Since mapping and demapping functions have a one-to-one correspondence, k = f _demap (k) outputs i = 0 and j = 1 when k = 1.
That is, d _{i, j} = Y _k indicates mapping of the received symbol Y _k to the group symbol d _{i, j} by (i, j) = f _demap (k).
Rewriting the group symbol is shown in Equation 17 below.

In addition, the symbol of Equation 17 may obtain a symbol shown in Equation 18 below through MRC (Maximum Ratio Combining) (S270).

이다. 심볼 d_j를 검파한 후 이것을 앞서 설명한 time-domain ICI 제거 알고리즘에서 사용한다(S270). Frequency diversity 이득을 얻을 수 있으므로 deep fade가 발생하더라도 심볼의 에너지를 크게 유지할 수 있다. 따라서 보다 정확한 재생성 신호를 얻게 되어 ICI 제거 효과가 증가하게 된다.
도 3은 제안한 repetition coding 기반의 time-domain ICI 제거 알고리즘을 보여주고 있다. 도 4는 제안한 알고리즘의 BER(Bit Error Rate) 성능을 보여준다. FD는 frequency diversity, 즉 repetition coding을 사용하였음을 나타내고, ICIM은 time-domain ICI 제거 알고리즘을 사용하였음을 나타낸다. FD+ICIM은 둘 모두를 사용하였음을 의미하며 제안한 알고리즘을 말한다. FD(x)의 숫자 x는 repetition을 x번 하였음을 나타낸다. ICIM(x)의 숫자 x는 iteration 횟수를 나타낸다. Repetition coding에 의한 spectral efficiency 저하를 막기 위해 변조지수를 높였다. 즉 QPSK 변조를16QAM 또는 64QAM으로 증가시켰다. here,

to be. After detecting the symbol d _j , it is used in the time-domain ICI elimination algorithm described above (S270). Since frequency diversity gain can be obtained, the energy of a symbol can be largely maintained even when a deep fade occurs. Thus, a more accurate regeneration signal is obtained, which increases the effect of removing ICI.
3 shows a time-domain ICI removal algorithm based on the proposed repetition coding. 4 shows the Bit Error Rate (BER) performance of the proposed algorithm. FD indicates that frequency diversity, that is, repetition coding is used, and ICIM indicates that a time-domain ICI removal algorithm is used. FD + ICIM means that both are used and the proposed algorithm. The number x of FD (x) indicates that the repetition has been performed x times. The number x of ICIM (x) represents the number of iterations. The modulation index is increased to prevent spectral efficiency degradation caused by repetition coding. That is, the QPSK modulation is increased to 16QAM or 64QAM.

Hereinafter, as a second embodiment of the present invention, a time domain ICI removal algorithm based on deep fade detection will be described.

5 is a conceptual diagram illustrating an application procedure of a Time Domain ICI removal algorithm based on Deep Fade Detection according to a second embodiment of the present invention.

Referring to FIG. 5, the deep fade detection method refers to a method of using only reliable data by detecting occurrence of a deep fade in a receiver and excluding data of a corresponding subcarrier location from an ICI interference cancellation algorithm. In the OFDM transmitter / receiver structure to which the deep fade detection algorithm is applied according to the second embodiment of the present invention, the transmitter structure follows a general OFDM transmitter. The difference is that in the receiver architecture, deep-fade detection is performed before the time-domain ICI cancellation algorithm. To do this, Equation 19 below is used.

은 신호대 잡음 전력비를 나타내고 H_m,m은 LS(Least Square) 채널추정 알고리즘에 의해 구한 채널 추정값이다. SNR을 구하기 위해 훈련심볼이나 검출한 데이터 심볼 등을 사용할 수 있다. 우선 신호대 잡음비 즉 SNR이 구해지고(S352), H_m,m이 측정됨으로써(S355) 수학식 19를 이용하여 m번째 부반송파의 채널 추정값이 (1/SNR) 이하로 떨어지면 m번째 감출한 데이터 심볼은 time-domain ICI 제거 알고리즘에서 제외된다(S357). 여기서 m은 0≤m≤N-1 범위의 정수이다.here,

Is the signal-to-noise power ratio and H _{m, m} is the channel estimate obtained by the LS (Least Square) channel estimation algorithm. In order to obtain the SNR, a training symbol or a detected data symbol can be used. First, the signal-to-noise ratio, i.e., SNR, is obtained (S352), and Hm _{, m} is measured (S355). When the channel estimation value of the mth subcarrier falls below (1 / SNR) using Equation 19, It is excluded from the time-domain ICI removal algorithm (S357). Where m is an integer in the range 0 ≦ m ≦ N-1.

Meanwhile, although not shown in the drawings as the third embodiment of the present invention, the first embodiment and the second embodiment may be combined. That is, the same symbol is allocated to different subcarriers in an OFDM transmitter by a repetition coding method and transmitted. In the OFDM receiver, the deep domain detection is used to apply a time domain ICI elimination algorithm to the remaining symbols except for a symbol in which a deep fade is generated. Could be. Detailed operations thereof are similar to those described above in the second and third embodiments, and thus detailed description thereof will be omitted.

On the other hand, as described above, by applying a repetition coding or deep fade detection algorithm to the existing time domain ICI removal algorithm, reliable data can be provided even when deep fade occurs.

Although the configuration of the present invention has been described in detail, it is only for illustrating the present invention, and the protection scope of the present invention is not limited thereto, and the protection scope of the present invention is defined through the description of the claims.

As described above, the ICI cancellation method of an orthogonal frequency division multiplexing system using repetition coding and deep fade detection according to an embodiment of the present invention eliminates adjacent channel interference (ICI) in an OFDM transmission / reception system for high speed transmission. By selectively applying the Repetition Coding or Deep Fade Detection algorithm to the communication environment according to the characteristics of the conventional Time Domain ICI elimination algorithm, it effectively removes ICI even in the case of deep fade and provides reliable data. Can improve.

In addition, the ICI cancellation method of the orthogonal frequency division multiplexing system using Repetition Coding and Deep fade Detection according to an embodiment of the present invention, by increasing the modulation index of the transmission signal to compensate for the spectral efficiency caused by Repetition Coding It is possible to provide reliable data by preventing problems that may occur in incorporating Repetition Coding into the Time Domain ICI removal algorithm.

Claims (20)

An interference cancellation method between adjacent channels in an OFDM transmission / reception system applying a repetition coding method to a time domain method, In order for the transmitter to allocate and transmit the same baseband symbol to different subcarriers, N _s data symbols {c _j | 0 ≦ _j ≦ N _s −1} are copied into M groups and group symbols {c _{i, j} | A first step of generating 0 ≦ j ≦ M−1,0 ≦ j ≦ N _s −1}; A second step of mapping each symbol of the group symbols to a subcarrier to generate a mapping group symbol {X _k | 0 ≦ _k ≦ N−1}; A third step of transmitting the mapping group symbol to a receiver through IDFT processing and CP insertion; A fourth step of removing and CPing the CP of the mapping group symbol at the receiver; A fifth step of extracting the unmapped group symbol from the subcarrier from the CP removal and DFT-processed mapping group symbol; Applying a MRC to the group symbol; And And generating a baseband symbol by applying a time domain ICI removal algorithm to the group symbols to which the MRC has been applied. 12. The method of claim 1, wherein the baseband symbols are generated using repetition coding. The method of claim 1, wherein the second step, Function to generate the mapping group symbol

ICI removal method of orthogonal frequency division multiplexing system using Repetition Coding. The method of claim 2, wherein f _map (i, j) of the function, ICI cancellation method of an orthogonal frequency division multiplexing system using repetition coding, characterized in that the j-th symbol of the i-th group is assigned to the k-th subcarrier. The method of claim 1, wherein the fifth step, Function for extracting the group symbols from the mapping group symbols

ICI removal method of orthogonal frequency division multiplexing system using Repetition Coding. The method according to claim 3 or 4, Among these functions, f _demap (k) is an arbitrary function of allocating symbols mapped to the k th subcarrier to the j th symbol of the i th group, which is an inverse process of f _map used by the transmitter.

Is

ICI removal method of orthogonal frequency division multiplexing system using Repetition Coding The method of claim 1, wherein the sixth step is The group symbol is a function for applying the MRC

ICI removal method of orthogonal frequency division multiplexing system using Repetition Coding The method of claim 1, ICI cancellation method of orthogonal frequency division multiplexing system using repetition coding, characterized in that to transmit the same baseband symbol to the sub-carrier to increase the modulation index of the transmission signal in order to prevent the degradation of the spectrum Efficieny. The method of claim 7, wherein ICI removal method of orthogonal frequency division multiplexing system using Repetition Coding, characterized in that for transmitting by increasing the modulation index to increase the QPSK modulation to 16QAM or 64QAM. An interference cancellation method between adjacent channels in an OFDM transmission / reception system using the deep domain detection method in a time domain method, A first step in which a baseband symbol is modulated and transmitted at a transmitter; Receiving a modulated baseband symbol at a receiver to obtain an SNR for detecting a deep fade; A third step of obtaining a channel estimate H _{m, m} using an LS channel estimation algorithm; a fourth step of determining the m-th detected baseband symbol as a deep fade generation symbol and excluding the baseband symbol when the H _{m, m} value of an _mth subcarrier falls below 1 / SNR; And And a fifth step of applying a time domain ICI elimination algorithm to baseband symbols other than the deep fade generation symbol. 2. The method according to claim 9, wherein H _{m , m} and SNR, Equation

ICI removal method of orthogonal frequency division multiplexing system using deep fade detection The method of claim 10, wherein the SNR, Equation

ICI removal method of orthogonal frequency division multiplexing system using deep fade detection, characterized in that obtained through.  An interference cancellation method between adjacent channels in an OFDM transmission / reception system using a repetition coding and deep fade detection technique in a time domain technique, In order for the transmitter to allocate and transmit the same baseband symbol to different subcarriers, N _s data symbols {c _j | 0 ≦ _j ≦ N _s −1} are copied into M groups and group symbols {c _{i , j} | A first step of generating 0 ≦ j ≦ M−1,0 ≦ j ≦ _s −1}; A second step of mapping each symbol of the group symbols to a subcarrier to generate a mapping group symbol {X _k | 0 ≦ _k ≦ N−1}; A third step of transmitting the mapping group symbol to a receiver through IDFT processing and CP insertion; A fourth step of removing a CP of the mapping group symbol by the receiver and performing a DFT process; A fifth step of extracting the unmapped group symbol from the subcarrier from the CP removal and DFT-processed mapping group symbol; Obtaining a SNR to receive the group symbol and detect a deep fade; A seventh step of obtaining a channel estimation value H _{m , m} using an LS channel estimation algorithm; An eighth step of determining the Mth detected group symbol as a deep fade generating symbol and excluding the corresponding group symbol when the H _{m , m} value of the Mth subcarrier falls below 1 / SNR; And And a ninth step of applying a time domain ICI removal algorithm to the group symbols except for the deep fade generation symbol; and removing the ICI of the orthogonal frequency division multiplexing system using repetition coding and deep fade detection. The method of claim 12, wherein the second step, Function to generate the mapping group symbol

ICI removal method of orthogonal frequency division multiplexing system using Repetition Coding and Deep fade Detection The method of claim 12, wherein f _map (i, j) of the function, ICI cancellation method of an orthogonal frequency division multiplexing system using repetition coding and deep fade detection, which is an arbitrary function of assigning the j-th symbol of the i-th group to the k-th subcarrier. The method of claim 12, wherein the fifth step, Function for extracting the group symbols from the mapping group symbols

ICI removal method of orthogonal frequency division multiplexing system using Repetition Coding and Deep fade Detection The method according to claim 14 or 15, Among these functions, f _demap (k) is an arbitrary function of allocating symbols mapped to the k th subcarrier to the j th symbol of the i th group, which is an inverse process of f _map used by the transmitter.

Is

ICI removal method of orthogonal frequency division multiplexing system using repetition coding and deep fade detection The method of claim 12, ICI elimination method of orthogonal frequency division multiplexing system using repetition coding and deep fade detection, characterized by increasing modulation index of transmission signal to prevent deterioration of spectral equality in allocating the same baseband symbol to subcarrier . The method of claim 17, ICI removal method of orthogonal frequency division multiplexing system using repetition coding and deep fade detection, characterized by increasing the modulation index to transmit QPSK modulation to 16QAM or 64QAM. The method according to claim 12, wherein H _{m , m} and SNR, Equation

ICI removal method of orthogonal frequency division multiplexing system using Repetition Coding and Deep fade Detection The method of claim 19, wherein the SNR is,

ICI removal method of orthogonal frequency division multiplexing system using repetition coding and deep fade detection, characterized in that obtained through.

Images