KR101051322B1 - Apparatus and method for transmitting and receiving pilot signals in a communication system using orthogonal frequency division multiplexing - Google Patents

Abstract

The present invention provides a method for transmitting a reference signal for distinguishing each of the cells in a communication system including a plurality of cells identified by a cell identifier. Generating a corresponding block code, generating a first part sequence by interleaving the block code using at least one interleaving scheme, performing an exclusive OR on the interleaved block code, and peak-to-average power Selecting a second part sequence corresponding to the cell identifier among predefined sequences in consideration of a decrease in ratio, and generating a reference signal in a frequency domain using the first part sequence and the second part sequence And inverse fast Fourier transform the reference signal in the frequency domain to a reference signal in the time domain. And converting the reference signal in the time domain in a reference signal transmission interval.

Pilot symbol, PAPR sequence, cell ID, sector ID, block code, Walsh basis, mask sequence, IFHT

Description

APPARATUS AND METHOD FOR TRANSMITTING / RECEIVING PILOT SIGNAL IN A COMMUNICATION SYSTEM USING ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SCHEME}             

1 is a view schematically showing all slopes that can be generated in a pilot pattern in a conventional OFDM communication system

2 illustrates an internal structure of a pilot signal generator of an OFDM communication system according to an embodiment of the present invention.

3 is a diagram illustrating an internal structure of a transmitter of an OFDM communication system according to an embodiment of the present invention.

4 is a diagram illustrating an internal structure of a receiver of an OFDM communication system according to an embodiment of the present invention.

FIG. 5 shows the internal structure of the cell ID / sector ID detector 419 of FIG.

6 is a flowchart illustrating a transmitter operation process in an OFDM communication system according to an embodiment of the present invention.

7 is a flowchart illustrating a receiver operation process in an OFDM communication system according to an embodiment of the present invention.

8 is a diagram schematically illustrating a mapping relationship between subcarriers and pilot symbols when performing an IFFT in an OFDM communication system according to an embodiment of the present invention.

9 illustrates a pilot symbol structure in a time domain of an OFDM communication system according to an embodiment of the present invention.

10 illustrates a pilot symbol structure in a frequency domain of an OFDM communication system according to an embodiment of the present invention.

The present invention relates to a communication system using orthogonal frequency division multiplexing, and more particularly, to an apparatus and method for transmitting and receiving pilot signals for distinguishing a base station and a sector.

In the 4th Generation (hereinafter, referred to as '4G') communication system, users of services having various quality of service (hereinafter referred to as 'QoS') having a high transmission rate are used by users. Active research is underway to provide it. In particular, in 4G communication systems, broadband, such as a wireless local area network (hereinafter referred to as "LAN") system and a wireless metropolitan area network (hereinafter referred to as "MAN") system, are widely used. Researches are being actively conducted to support high-speed services in a form of guaranteeing mobility and QoS in a wireless access (BWA) communication system.

Therefore, in the 4G communication system, orthogonal frequency division multiplexing (OFDM) is actively studied as a method useful for high-speed data transmission in wired and wireless channels. The method uses a multi-carrier to transmit data. A plurality of sub-carriers each having orthogonality to each other by converting serially input symbol strings in parallel. It is a kind of multi-carrier modulation (MCM) that modulates and transmits data.

Broadband spectrum resources are required for the 4G communication system to provide high speed, high quality wireless multimedia services. However, when the broadband spectrum resource is used, fading effects on the radio transmission path due to multipath propagation become serious and frequency selective fading also occurs within the transmission band. Therefore, the OFDM scheme, which is robust against frequency selective fading, has a greater gain than the code division multiple access (CDMA) scheme for high-speed wireless multimedia services. There is a trend that is actively used in the system.

Here, the operation of the transmitter and the receiver of the communication system using the OFDM scheme (hereinafter referred to as 'OFDM communication system') will be briefly described as follows.

In the transmitter of the OFDM communication system, input data is modulated into subcarriers through a scrambler, an encoder, and an interleaver. In this case, the transmitter provides various variable data rates, and has different coding rates, interleaving sizes, and modulation schemes according to the data rates. Typically, the encoder uses coding rates such as 1/2, 3/4, etc., and the size of the interleaver for preventing burst errors is the number of coded bits per OFDM symbol (NCBPS). Bits per Symbol). In addition, the modulation scheme may be a Quadrature Phase Shift Keying (QPSK) scheme, a Phase Shift Keying (8PSK) scheme, a Quadrature Amplitude Modulation (16QAM) scheme, a 64QAM scheme, or the like, depending on the data rate.

On the other hand, a signal modulated with a predetermined number of subcarriers by the above configurations is added to a predetermined number of pilot subcarriers, which is an Inverse Fast Fourier Transform (IFFT). IFFT is performed to generate one OFDM symbol. Thereafter, a guard interval for removing inter symbol interference (ISI) in a multi-path channel environment is inserted into the OFDM symbol, and the OFDM symbol into which the guard interval signal is inserted is inserted. The symbol waveform generator is finally input to a radio frequency (RF) processor. The radio frequency processor wirelessly processes an input signal and transmits the received signal.

Here, the guard interval is inserted to remove intersymbol interference between the OFDM symbol transmitted at the previous OFDM symbol time and the current OFDM symbol to be transmitted at the current OFDM symbol time when transmitting the OFDM symbol. In addition, the guard interval is a 'cyclic prefix' scheme in which the last constant samples of the OFDM symbols in the time domain are copied and inserted into a valid OFDM symbol, or the first constant samples of the OFDM symbols in the time domain. It is inserted in a 'cyclic postfix' manner in which it is copied and inserted into a valid OFDM symbol.

The receiver of the OFDM communication system corresponding to the transmitter as described above performs an inverse process to the process performed by the transmitter, and further performs a synchronization process.

In more detail, first, a process of estimating a frequency offset and a symbol offset using a training symbol preset for a received OFDM symbol should be preceded. Subsequently, the data symbol from which the guard interval is removed is recovered to a predetermined number of subcarriers to which a predetermined number of pilot subcarriers are added through a Fast Fourier Transform (FFT). Also, in order to overcome the path delay phenomenon on the actual radio channel, the equalizer estimates the channel state of the received channel signal to remove the signal distortion on the actual radio channel from the received channel signal. The channel estimated data through the equalizer is converted into a bit stream, passed through a de-interleaver, and then a decoder and descrambler for error correction. The final data is output via

Meanwhile, as described above, in an OFDM communication system, a transmitter such as a base station (BS) transmits pilot subcarrier signals to a receiver such as a mobile station (MS). The base station transmits the data subcarrier signals simultaneously with the pilot subcarrier signals. The reason for transmitting the pilot subcarrier signals is for synchronization acquisition, channel estimation, and base station division. That is, the pilot subcarrier signal is a kind of reference sub-carrier signal. The pilot subcarrier signals operate as a kind of training sequence and enable channel estimation between the transmitter and the receiver. In addition, the terminal may identify the base station to which the terminal belongs by using the pilot subcarrier signals. The position at which the pilot subcarrier signals are transmitted is pre-defined between the transmitter and the receiver. As a result, the pilot subcarrier signals operate as a kind of reference signal.

Next, an operation of identifying a base station to which a terminal belongs by using the pilot subcarrier signals will be described.

First, a base station may reach a cell boundary with a relatively high transmit power compared to the data subcarrier signals while the pilot subcarrier signals have a specific pattern, that is, a pilot pattern. Send it to be. Here, the base station transmits the pilot subcarrier signals to reach a cell radius with a relatively high transmission power while having a specific pilot pattern as follows.

First, when the terminal enters a cell, the terminal does not have any information about the base station to which the terminal currently belongs. The terminal must use the pilot subcarrier signals to detect the base station to which the terminal belongs, so that the base station transmits the pilot subcarrier signals at a relatively high transmit power while having a specific pilot pattern. Allow the terminal to detect the base station to which the terminal belongs.

Meanwhile, the pilot pattern refers to a pattern generated by pilot subcarrier signals transmitted from a base station. That is, the pilot pattern is determined by a slope of the pilot subcarrier signals and a start point at which the pilot subcarrier signals begin to be transmitted. Thus, the OFDM communication system must be designed such that each of the base stations has a different pilot pattern to distinguish each of the base stations constituting the OFDM communication system. In addition, the pilot pattern is generated in consideration of a coherence bandwidth and a coherence time. Next, the coherence bandwidth and the coherence time will be described.

The coherence bandwidth represents the maximum bandwidth that can be assumed to be constant in the frequency domain. The coherence time represents the maximum time that can be assumed that the channel does not change in the time domain. Since it can be assumed that the channel does not change within the coherence bandwidth and the coherence time, even if only one pilot subcarrier signal is transmitted during the coherence bandwidth and the coherence time, synchronization acquisition and channel estimation and base station Division etc. becomes possible.

Thus, since only one pilot subcarrier signal is transmitted, transmission of data subcarrier signals can be maximized, thereby improving system overall performance. As a result, the maximum frequency interval for transmitting the pilot subcarrier signal is a coherence bandwidth, and the maximum time interval for transmitting the pilot subcarrier signal, that is, the maximum OFDM symbol time interval, is the coherence time.

On the other hand, the number of base stations constituting the OFDM communication system varies depending on the size of the OFDM communication system, but typically increases as the size of the OFDM communication system increases. Therefore, in order to distinguish each of the base stations, pilot patterns having different slopes and starting points must exist as many as the base stations. However, in order to transmit a pilot subcarrier signal in a time-frequency domain in the OFDM communication system, a coherence bandwidth and a coherence time must be considered as described above, and the coherence bandwidth and In consideration of the coherence time, pilot patterns having different slopes and starting points are generated in a limited manner. When generating a pilot pattern without considering the coherence bandwidth and the coherence time, pilot subcarrier signals in pilot patterns representing different base stations are mixed, and in this case, it is necessary to distinguish the base stations using the pilot pattern. impossible.

Next, with reference to FIG. 1, when a pilot subchannel is used in a typical OFDM communication system, a position in which pilot subcarriers are transmitted according to a pilot pattern will be described.

FIG. 1 is a diagram schematically showing locations where pilot subcarriers are transmitted according to a pilot pattern when using one pilot subchannel in a conventional OFDM communication system.

Referring to FIG. 1, the slopes and the number of slopes that can be generated in the pilot pattern, that is, the slopes and the number according to the pilot subcarrier signal transmission are determined according to the coherence bandwidth 100 and the coherence time 110. Limited. In FIG. 1, when the coherence bandwidth 110 is 6 and the coherence time 110 is 1, assuming that the slope of the pilot pattern is an integer, the slope of the pilot pattern that may occur under the above condition is s = There are six numbers from 0 (101) to s = 5 (106). That is, the slope of the pilot pattern that can be generated under the above condition is any integer value from 0 to 5.

In this way, the six possible slopes of the pilot pattern means that the number of base stations that can be distinguished using the pilot pattern in the OFDM communication system satisfying the condition is six. In addition, the diagonally processed circles 107 illustrated in FIG. 1 represent pilot subcarrier signals spaced apart by the coherence bandwidth 100. As a result, the slope of the pilot pattern is limited to the coherence versus bandwidth 100.

As described above, the pilot pattern used to distinguish the base stations constituting the OFDM communication system in the OFDM communication system is generated by being limited to the coherence bandwidth and the coherence time. Occurs. Thus, when the number of base stations constituting the OFDM communication system increases, there is a problem in that a limit occurs in the number of distinguishable base stations due to a limitation in the number of patterns that can be generated.

Accordingly, an object of the present invention is to provide an apparatus and method for transmitting and receiving pilot signals for base station and sector classification in an OFDM communication system.

Another object of the present invention is to provide an apparatus and method for transmitting and receiving pilot signals to minimize mutual interference in an OFDM communication system.

Another object of the present invention is to provide an apparatus and method for transmitting and receiving pilot signals having a variable length in an OFDM communication system.

Another object of the present invention is to provide an apparatus and method for transmitting and receiving pilot signals using a block code generated by using a Walsh basis and a mask sequence in an OFDM communication system.

The method proposed in the present invention; A method for transmitting a reference signal for distinguishing each of the cells in a communication system including a plurality of cells identified by a cell identifier, the method comprising: when a cell identifier is input, a block corresponding to the cell identifier using a block code generation matrix Generating a first part sequence by interleaving the block code using at least one interleaving scheme, performing an exclusive OR on the interleaved block code, and reducing a peak-to-average power ratio. Selecting a second part sequence corresponding to the cell identifier from among predefined sequences, generating a reference signal in a frequency domain using the first part sequence and the second part sequence, and Inverse fast Fourier transform of a reference signal in the frequency domain to a reference signal in the time domain And transmitting a reference signal of the time domain in a reference signal transmission interval.

The device proposed in the present invention; In a communication system including a plurality of cells separated by a cell identifier, the apparatus for transmitting a reference signal for distinguishing each of the cells, if a cell identifier is input, corresponding to the cell identifier using a block code generation matrix A block code encoder for generating a block code, an interleaver for interleaving the block code using at least one interleaving scheme, an adder for exclusively ORing the Walsh codes repeated in the interleaved block code to generate a first part sequence, and A combiner for generating a reference signal in a frequency domain using the first part sequence and a second part sequence selected corresponding to the cell identifier among predetermined sequences; and in the preset reference signal transmission interval, the frequency Inverse fast Fourier transform of the region's reference signal to a reference signal in the time domain After bright, and a transmitter for transmitting a reference signal in the time domain.

Another method proposed by the present invention; Including a plurality of cells separated by cell identifiers In a communication system, a method of receiving a reference signal for distinguishing each of the plurality of cells, the method comprising: extracting a reference signal from a fast Fourier transformed received signal; Exclusive OR of the repeated signals and the repeated Walsh code, deinterleaving the exclusive OR signal using at least one deinterleaving method, and sub-interleaving the deinterleaved signal using a block code generation matrix. Dividing into block signals, performing inverse fast Hadamard transformation using each of the mask sequences on each of the subblock signals, and combining the inverse fast Hadamard transformed signals to generate a combined signal And a maximum correlation value among combined signals corresponding to each of the plurality of cell identifiers. Loss includes detecting the cell identifier corresponding to the block code as the final cell identifier.

Another apparatus proposed by the present invention; In a communication system including a plurality of cells identified by a cell identifier, an apparatus for receiving a reference signal for distinguishing each of the plurality of cells, the apparatus comprising: a fast Fourier transformer for fast Fourier transform the received signal, and the fast Fourier transform A reference signal extractor for extracting a reference signal from a signal, an adder for dividing the reference signal in units of a predetermined number of predetermined intervals, and an exclusive OR of the Walsh codes repeated to the divided signals, and the exclusive OR signal A deinterleaver for deinterleaving using at least one deinterleaving scheme, a subblock divider for dividing the deinterleaved signal into subblock signals corresponding to a predetermined block code generation matrix, and each of the subblock signals Inverse fast Hadamard transform using each of the mask sequences for A code decoder, a combiner for combining the inverse fast Hadamard transformed signals, and a cell identifier corresponding to a block code having a maximum correlation value among combined signals corresponding to each of the plurality of cell-specific identifiers are detected as a final cell identifier. A comparison selector.

Another method proposed by the present invention is; A communication system including a plurality of cells identified by a cell identifier, the method for transmitting a reference signal for distinguishing each of the plurality of cells through at least one transmitting antenna, the method comprising: receiving a cell identifier; Generating a block code corresponding to the cell identifier using a generation matrix, selecting a Walsh code corresponding to the cell identifier among predefined Walsh codes and repeating the block code a predetermined number of times; Interleaving in an interleaving manner, generating an first part sequence by exclusively ORing the interleaved block code and the repeated Walsh code, and selecting a second part sequence corresponding to the cell identifier among predefined sequences And a reference signal in a frequency domain using the first part sequence and the second part sequence One by the reference signal generation process and the frequency domain, an inverse fast Fourier transform conversion to the reference signal in the time domain and then, in a pre-defined reference signal transmission block, and includes the step of transmitting a reference signal in the time domain.

Another method proposed by the present invention is; CLAIMS 1. A method for providing pilot symbols for base station identification in a multiple input multiple output communication system comprising one or more transmit antennas, the method comprising: generating pilot symbols; The pilot symbol includes a first part sequence having cell discrimination characteristics and a second part sequence having reduced peak-to-average power ratio characteristics for all pilot symbols.

Hereinafter, with reference to the accompanying drawings in accordance with the present invention will be described in detail. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

The present invention relates to a base station (BS) in a communication system (hereinafter referred to as an 'OFDM communication system') using an orthogonal frequency division multiplexing (OFDM) scheme. And a method of transmitting and receiving a pilot signal for sector division. In particular, the present invention proposes a method for transmitting and receiving a pilot signal through one or more antennas to minimize the interference while performing the base station and sector classification in an OFDM communication system.

2 is a diagram illustrating the internal structure of a pilot generator of an OFDM communication system according to an embodiment of the present invention.

Referring to FIG. 2, the pilot signal generator includes a block code encoder 201, an interleaver 203, and a Walsh code repeater 205. And an adder 207 and a combiner 209.

First, a cell identifier (ID) (hereinafter, referred to as 'ID') is an ID for identifying a cell, that is, a base station (BS), and the cell ID is the block code encoder 201. Is entered. As the cell ID is input, the block code encoder 201 generates a codeword corresponding to the cell ID, that is, a block code, from the generator matrix G, which is already stored, and then the interleaver 203. ) The generation matrix G is generated such that each of the block codes generated corresponding to the cell ID can be clearly distinguished from each other. The generation matrix G will be described with reference to Table 1 below.                     

개의 셀들을 구별할 수 있다. 상기 생성 행렬 G의 N_c개의 열들을 a개의 서브 블록(sub-block)들로 구분되고, 따라서 상기 a개의 서브 블록들 각각은

의 길이를 갖으며, 상기 길이

가 채널의 코히어런스 대역폭(coherence bandwidth) 미만이 되도록 설계된다. 상기 a개의 서브 블록들 각각은

개의 왈쉬 기저(Walsh basis)들과 n개의 마스크 시퀀스(mask sequence)들 로 구성된다. 여기서, 상기 a개의 서브 블록들 각각을 구성하는 왈쉬 기저들은 모두 동일한 왈쉬 기저들이며, 상기 마스크 시퀀스들의 개수 n은

와 같다. 상기 표 1에서 마스크_(p)는 제p마스크 시퀀스를 나타내며, 상기 생성 행렬 G에서 제2서브 블록은 제1서브 블록의 행들이 n-1번 순환 쉬프트(cyclic shift)되어 생성되며, 상기와 같은 방식으로 제m서브 블록은 제1서브 블록의 행들이 n-j번 순환 쉬프트되어 생성된다. 상기 순환 쉬프트 동작은 상기 생성 행렬 G를 사용하여 생성되는 블록 코드의 최소 거리(minimum distance)를 최대화시키는 형태로 수행되는 것이다. First, assuming that the number of rows of the generation matrix G is N _r and the number of columns is N _c , the length N _G of the block code that can be generated using the generation matrix _G is the generation. Equivalent to N _c , the number of columns in the matrix G. In addition, the pilot symbol generated by the block code is the maximum

Cells can be distinguished. N _c columns of the generation matrix G are divided into a sub-blocks, and thus each of the a sub-blocks

Has a length of and the length

Is designed to be less than the coherence bandwidth of the channel. Each of the a sub blocks

It consists of Walsh basis and n mask sequences. Here, the Walsh bases constituting each of the a sub-blocks are all the same Walsh bases, and the number n of the mask sequences is

Same as In Table 1, mask _(p) represents a pth mask sequence, and the second sub block in the generation matrix G is generated by cyclically shifting the rows of the first sub block n-1 times. In this manner, the m-th sub block is generated by shifting the rows of the first sub block nj times. The cyclic shift operation is performed in a form of maximizing a minimum distance of a block code generated using the generation matrix G.

The interleaver 203 inputs a signal output from the block code encoder 201, interleaves the interleaving method in a predetermined interleaving manner, and outputs the signal to the adder 207. Here, the reason why the interleaver 203 interleaves the signal output from the block code encoder 201 is that the block code generated by the block code encoder 201, that is, corresponding to the specific cell ID, is generated in a specific pattern. This is because the peak-to-average power ratio (PAPR) will be high when the numeric string has a feature that is frequently repeated. That is, the interleaver 203 controls to improve the PAPR characteristic of the pilot signal of the OFDM communication system by interleaving all block codes generated by the block code encoder 201.

Next, the internal structure of the interleaver 203 will be described below.                     

First, the interleaver 203 has a internal interleaver (not shown) therein and interleaves a signal generated through each of the a subblocks of the generation matrix G. That is, the block code output from the block code encoder 201 is divided into a sub-codes, and each of the a sub-codes is interleaved differently in each of the a internal interleavers. Since the interleaver 203 performs interleaving on each of the a subcodes of the block code, the receiver will use the Walsh basis to refer to an Inverse Fast Hadamard Transform (IFHT). ), It is possible to decode the information data corresponding to the block code transmitted from the transmitter side.

On the other hand, a sector ID is an ID for identifying a sector, and the sector ID is input to the Walsh code repeater 205. When the sector ID is input, the Walsh code repeater 205 repeats the Walsh code corresponding to the sector ID a predetermined number of times and outputs the Walsh code iterator to the adder 207.

번 반복하여 출력한다. 여기서, 상기 왈쉬 코드 반복기(205)에서 출력하는 신호의 길이는 상기 인터리버(203)에서 출력하는 신호의 길이 N_G와 동일하다. In an embodiment of the present invention, a pilot signal of the OFDM communication system, for example, a pilot symbol length is N _P , a block code length generated by the block code encoder 201 is N _G , and the Walsh code is used. It is assumed that the length of is N _W. In this case, the Walsh code iterator 205 generates a Walsh code corresponding to the sector ID.

Repeat the output once. Here, the length of the signal output from the Walsh code repeater 205 is equal to the length N _G of the signal output from the interleaver 203.

The adder 207 calculates an exclusive OR (XOR) operation of the signal output from the interleaver 203 and the signal output from the Walsh code repeater 205 and outputs the result to the combiner 209.

이 된다.Meanwhile, the PAPR reduction sequence is a sequence for reducing PAPR of pilot symbols in the OFDM communication system, and the length of the PAPR reduction sequence is N _R. Here, it is assumed that the PAPR reduction sequence is predetermined according to the cell ID and sector ID in the OFDM communication system. The PAPR reduction sequence will be described in detail below, and thus a detailed description thereof will be omitted. do. The PAPR reduction sequence having the length N _R is input to the combiner 209, and the combiner 209 generates a pilot symbol by allocating a signal output from the adder 207 and the PAPR sequence to a corresponding subcarrier. Output Here, the length of the pilot symbol output from the combiner 209 is

Becomes

2 illustrates the internal structure of a pilot signal generator of an OFDM communication system according to an embodiment of the present invention. Next, the internal structure of a transmitter of the OFDM communication system according to an embodiment of the present invention will be described with reference to FIG. Shall be.

3 is a diagram illustrating an internal structure of a transmitter of an OFDM communication system according to an embodiment of the present invention.

Referring to FIG. 3, the transmitter includes a modulator 1 (301), a pilot signal generator 303, a modulator 2 (305), a selector 307, and a serial to parallel converter. 309, an Inverse Fast Fourier Transform (IFFT) device 311, a parallel to serial converter 313, and a guard interval. A guard interval inserter 315, a digital to analog converter 317, and a radio frequency (RF) processor 319 ).

First, when data to be transmitted, namely information data bits, is generated, the information data bits are input to the modulator 1 (301). The modulator 1 301 modulates the input information data bits by using a preset modulation method to generate a modulated symbol and outputs the modulated symbols to the selector 307. Here, the modulation scheme may be a quadrature phase shift keying (QPSK) scheme or a 16-array quadrature amplitude modulation (QAM) scheme.

In addition, when a pilot signal, that is, a pilot symbol is to be transmitted, a cell ID of a cell and a sector to which the pilot symbol is to be transmitted, a sector ID, and a PAPR reduction sequence preset in correspondence with the cell ID and the sector ID are pilots. It is input to the signal generator 303. The pilot signal 303 generates the input cell ID, sector ID, and PAPR reduction sequence as pilot symbols, and outputs them to the modulator 2 (305). Here, the internal structure of the pilot signal generator 303 is as described with reference to FIG. The modulator 305 inputs a signal output from the pilot signal generator 303, modulates the modulated signal with a preset modulation scheme, generates a modulated symbol, and outputs the modulated symbol to the selector 307. Here, a binary phase shift keying (BPSK) scheme may be used as the modulation scheme.

The selector 307 controls to output the signal output from the modulator 1 301 to the serial / parallel converter 309 in the data symbol transmission interval in which the transmitter should transmit a current data symbol. In the pilot symbol transmission interval in which the transmitter should transmit the current pilot symbol, the transmitter outputs the signal output from the modulator 305 to the serial / parallel converter 309. The serial / parallel converter 309 receives the serial modulation symbols output from the selector 307, converts them in parallel, and then outputs them to the IFFT unit 311. The IFFT unit 311 inputs a signal output from the serial / parallel converter 309 to perform an N-point IFFT and then outputs it to the parallel / serial converter 313.

The parallel / serial converter 313 inputs the signal output from the IFFT device 311 and serially converts the signal, and outputs the serial signal to the guard interval inserter 315. The guard interval inserter 315 inputs a signal output from the parallel / serial converter 313 to insert a guard interval signal and then outputs the guard interval signal to the digital / analog converter 317. Here, the guard interval is inserted to remove interference between the OFDM symbol transmitted at the previous OFDM symbol time and the current OFDM symbol transmitted at the current OFDM symbol time when the OFDM symbol is transmitted in the OFDM communication system. . In addition, the guard interval is a 'Cyclic Prefix' method of copying the last predetermined samples of the OFDM symbols in the time domain and inserting them into the valid OFDM symbols, or by copying the first predetermined samples of the OFDM symbols in the time domain. Inserted using any one of the 'Cyclic Postfix' method to insert into the symbol. The signal output from the guard interval inserter 315 results in one OFDM symbol.

The digital-to-analog converter 317 inputs the signal output from the guard interval inserter 315 and converts the signal to the RF processor 319. Here, the RF processor 319 may include components such as a filter and a front end unit. The RF processor 319 may perform an RF processing on a signal output from the digital-to-analog converter 317 and then perform an antenna. Send via

3 illustrates the internal structure of a transmitter of an OFDM communication system according to an embodiment of the present invention. Next, the internal structure of a receiver of an OFDM communication system according to an embodiment of the present invention will be described with reference to FIG. .

4 is a diagram illustrating an internal structure of a receiver of an OFDM communication system according to an embodiment of the present invention.

Referring to FIG. 4, the receiver includes an RF processor 401, an analog / digital converter 403, a guard interval remover 405, and a serial / parallel converter. 407, Fast Fourier Transform (FFT), 409, parallel / serial converter 411, selector 413, and demodulator (de-modulator). 1,2 (415,417) and cell ID / sector ID detector 419.

First, a signal transmitted from a transmitter of the OFDM communication system is received through an antenna of the receiver in the form of a multipath channel and a noise component added thereto. The signal received through the antenna is input to the RF processor 401, and the RF processor 401 down converts the signal received through the antenna to an intermediate frequency (IF) band. After the output to the analog-to-digital converter 403. The analog / digital converter 403 digitally converts the analog signal output from the RF processor 301 and outputs the digital signal to the guard interval remover 405.

The guard interval remover 405 removes the guard interval signal by inputting the signal output from the analog / digital converter 403 and outputs the signal to the serial / parallel converter 407. The serial / parallel converter 407 inputs a serial signal output from the guard interval eliminator 405 to perform parallel conversion and outputs the serial signal to the FFT unit 409. The FFT unit 409 outputs the signal output from the serial / parallel converter 407 to the parallel / serial converter 411 after performing an N-point FFT.

The parallel / serial converter 411 inputs a parallel signal output from the FFT unit 409, serially converts the same, and outputs the serial signal to the selector 413. The selector 413 controls to output the signal output from the FFT unit 409 to the demodulator 1 415 when the receiver is in a data symbol reception interval in which the receiver should receive a current data symbol, and the receiver is present pilot. In the pilot symbol reception period in which the symbol should be received, the control unit outputs the signal output from the FFT unit 409 to the demodulator 2 417. The demodulator 1 415 demodulates the signal output from the FFT unit 409 in accordance with the modulation scheme applied by the transmitter and restores the data, that is, the information data bits.

On the other hand, the demodulator 2 417 demodulates the signal output from the FFT unit 409 in accordance with the modulation scheme applied by the transmitter to restore the pilot and outputs the signal to the cell ID / sector ID detector 419. The cell ID / sector ID detector 419 inputs a pilot signal output from the demodulator 2 417 to detect a cell ID and a sector ID corresponding to the pilot signal. Here, the pilot signal is a signal generated corresponding to the cell ID and the sector ID, and is mutually regulated between the transmitter and the receiver.

In FIG. 4, the internal structure of the receiver of the OFDM communication system according to the embodiment of the present invention has been described. Next, the internal structure of the cell ID / sector ID detector 419 of FIG. 4 will be described with reference to FIG. .

5 is a diagram illustrating an internal structure of the cell ID / sector ID detector 419 of FIG. 4.

Referring to FIG. 5, the cell ID / sector ID detector 419 includes a pilot extractor 501, a Walsh code iterator 503, an adder 505, a de-interleaver 507, And a sub-block segment unit 509, a block code decoder 511, a combiner 523, and a comparison selector 525. The block code decoder 511 includes a multiplier 513, a mask sequence generator 515, an IFHT generator 517, a memory 519, and a controller 521.

First, the signal output from the demodulator 2 417 of FIG. 4 is input to the pilot signal extractor 501, and the pilot signal extractor 501 inputs the signal output from the demodulator 417 to reduce the PAPR sequence. After extracting N _G symbols to extract the output to the adder (505). In addition, the Walsh code repeater 503 repeatedly outputs Walsh codes corresponding to all distinguishable sector IDs, and the receiver sequentially selects one Walsh code among the Walsh codes corresponding to all sector IDs. After repeating the output to the adder 505.

The adder 505 performs an exclusive OR operation on the signal output from the pilot signal extractor 501 and the signal output from the Walsh code repeater 503 and then outputs the deinterleaver 507. The deinterleaver 507 uses a deinterleaving scheme corresponding to an interleaving scheme in which the signal output from the adder 505 is applied by an interleaver inside the pilot signal generator of the transmitter, that is, the interleaver 203 of FIG. 2. After interleaving, the result is output to the subblock divider 509.

The sub block divider 509 inputs the signal output from the deinterleaver 507 and divides the signal into sub blocks such as the block code generation matrix G on the transmitter side as described in Table 1 above. That is, the signal is divided into a subblocks and sequentially output to the block code decoder 511. Here, the sub block divider 509 divides the signal output from the deinterleaver 507 into a sub blocks, stores each of the a sub blocks in an internal memory (not shown). The sub blocks are sequentially delayed from the first sub block among the a sub blocks until the a sub block, which is the last sub block, is output to the block code decoder 511.

The signal output from the sub-block divider 509 is input to the multiplier 513 of the block code decoder 511, and the multiplier 513 outputs the mask sequence and the sub-block output from the mask sequence generator 515. The signal output from the divider 509 is multiplied and then output to the IFHT divider 517. Here, the mask sequence generator 515 sequentially generates each of the mask sequences used in the block code generation matrix G on the transmitter side and outputs them to the multiplier 513 under the control of the controller 521.

The IFHT 517 inputs the signal output from the multiplier 513 to perform an IFHT operation and outputs the signal to the memory 519. The memory 519 stores the signal output from the IFHT device 517 and outputs the signal to the controller 521 again. The controller 521 controls the mask sequence generation operation of the mask sequence generator 515. In addition, the controller 521 stores the deinterleaver 507 stored in the memory 519 after the mask sequence generator 515 generates all mask sequences used in the block code generation matrix G on the transmitter side. The output value of the IFHT group 517 corresponding to the mask sequences of the corresponding sub block of the output signal is controlled to be output to the combiner 523.

The combiner 523 stores the signal output from the controller 521, that is, the controller 521 stores the signals output for each of the sub-blocks of the deinterleaver 507 output signal. The output values output from the IFHT group 517 are combined and output to the comparison selector 525 corresponding to the block code generation matrix G of the transmitter.

The comparison selector 525 selects a correlation value having a maximum value among the output correlation values of the combiner 523 for the block codes corresponding to all the cell IDs and the Walsh codes corresponding to all the sector IDs. The cell ID and sector ID corresponding to the selected maximum correlation value are detected and output as the last cell ID and the last sector ID.

In FIG. 5, the internal structure of the cell ID / sector ID detector 419 of FIG. 4 has been described. Next, a transmitter operation process in an OFDM communication system according to an embodiment of the present invention will be described with reference to FIG. 6. .

6 is a flowchart illustrating a transmitter operation process in an OFDM communication system according to an embodiment of the present invention.

In FIG. 6, only the pilot signal transmission operation of the transmitter will be described. Referring to FIG. 6, in step 611, the transmitter generates a pilot symbol using a cell ID, a sector ID, and a PAPR reduction sequence of the transmitter, and then proceeds to step 613. Since the operation of generating the pilot symbol is the same as described with reference to FIG. 2, the detailed description thereof will be omitted. In step 613, the transmitter modulates the generated pilot symbol into a modulation scheme, such as a BPSK scheme, which is generated in advance.

In step 615, the transmitter terminates after transmitting the modulated symbol-converted pilot symbol in a pilot symbol period. Of course, although not separately illustrated in FIG. 6, a frequency offset may be considered in transmitting the pilot symbol. That is, the position at which the pilot symbol starts may be different for each cell and sector.

In FIG. 6, a transmitter operation process in an OFDM communication system according to an embodiment of the present invention has been described. Next, a receiver operation process in an OFDM communication system according to an embodiment of the present invention will be described with reference to FIG. 7. .

7 is a flowchart illustrating a receiver operation process in an OFDM communication system according to an embodiment of the present invention.

In FIG. 7, only the pilot signal reception operation of the receiver will be described. Referring to FIG. 7, first, in step 711, the receiver receives a pilot symbol in a pilot symbol period and then proceeds to step 713. Although not separately illustrated in FIG. 7, when the transmitter transmits the pilot symbol in consideration of the frequency offset as described in FIG. 6, the receiver determines the position according to the frequency offset and then receives the pilot symbol. Of course it can. In step 713, the receiver demodulates the pilot symbols according to the modulation scheme applied by the transmitter, and then proceeds to step 715. In step 715, the receiver correlates the demodulated pilot symbols with block codes corresponding to all cell IDs distinguishable from the receiver and Walsh codes corresponding to all sector IDs, and thereafter, a maximum correlation value among them. The cell ID and the sector ID having are detected as the cell ID and the sector ID of the transmitter and then terminate.

In FIG. 7, a receiver operation process in an OFDM communication system according to an embodiment of the present invention has been described. Next, subcarriers and pilot symbols are performed when performing IFFT in an OFDM communication system according to an embodiment of the present invention. The mapping relationship with will be described.

8 is a diagram illustrating a mapping relationship between subcarriers and pilot symbols when performing an IFFT in an OFDM communication system according to an embodiment of the present invention.

In FIG. 8, when the total number of subcarriers used in the OFDM communication system is 128 and the number of subcarriers actually used among the 128 subcarriers is 108, that is, subcarriers -54 to -1 Assume that 54 subcarriers up to a carrier and 54 subcarriers from subcarriers 1 to 54 are used, that is, 108 subcarriers in total. In FIG. 8, the number k on the top of the input terminal of the IFFT unit represents an index of subcarriers of the OFDM communication system. In addition, since subcarrier # 0 represents a reference point of the pilot symbol in the time domain, that is, a DC component in the time domain after performing the IFFT, null data is inserted into the subcarrier # 0.

Further, the 108 subcarriers actually used, subcarriers except the subcarrier 0, that is, subcarriers from sub-55 subcarrier to sub-64 subcarrier, subcarriers 55 through 63 Null data is also inserted in the subcarriers up to the subcarrier.                     

Here, the reason why null data is inserted into subcarriers from subcarriers -55 to -64 and subcarriers from subcarriers 55 to 63 is described. The subcarriers up to subcarrier 64 and the subcarriers up to subcarrier 55 through 63 are adjacent to the frequency band of another system, so the interference with other systems is minimized. Thus, when a pilot symbol in the frequency domain is input to the IFFT device, the IFFT device maps the pilot symbols in the frequency domain to the corresponding subcarriers to perform IFFT and outputs the pilot symbols in the time domain.

8 illustrates a mapping relationship between subcarriers and pilot symbols when performing an IFFT in an OFDM communication system according to an embodiment of the present invention. Next, an OFDM communication system according to an embodiment of the present invention will be described with reference to FIG. The pilot symbol structure in the time domain will be described.

9 illustrates a pilot symbol structure in a time domain of an OFDM communication system according to an embodiment of the present invention.

길이의 심벌이 2번 반복된 형태를 가지며, OFDM 통신 시스템의 특성상 상기에서 설명한 바와 같은 Cyclic Prefix(CP) 방식으로 삽입된 보호 구간 신호가 상기

길이의 심벌이 2번 반복된 형태의 전단에 첨가되어 있다. 여기서, 상기 N_FFT는 상기 OFDM 통 신 시스템에서 사용하는 IFFT기/FFT기의 포인트 수를 나타낸다. 즉, 상기 도 8에서도 설명한 바와 같이 상기 OFDM 통신 시스템에서 사용하는 IFFT기/FFT기의 포인트 수가 128이므로 상기 p_c의 길이는 64가 되는 것이다. 9, the pilot symbol is of length p _c , that is,

The symbol of length has a form repeated twice, and the guard interval signal inserted in the Cyclic Prefix (CP) method as described above is a characteristic of the OFDM communication system.

A symbol of length is added to the front end of the form repeated twice. Here, the N _FFT represents the number of points of the IFFT / FFT group used in the OFDM communication system. That is, as described in FIG. 8, the length of p _c is 64 since the number of points of the IFFT / FFT group used in the OFDM communication system is 128.

9 illustrates a pilot symbol structure in a time domain of an OFDM communication system according to an embodiment of the present invention. Next, with reference to FIG. 10, a pilot symbol in a frequency domain of an OFDM communication system according to an embodiment of the present invention. The structure will be described.

10 illustrates a pilot symbol structure in a frequency domain of an OFDM communication system according to an embodiment of the present invention.

Referring to FIG. 10, first, guard bands (GB) 1001 and 1007, that is, subcarrier intervals excluding guard intervals, are largely classified into a correlation interval 1003 and a PAPR interval 1005. . The correlation section 1003 includes a sequence having a large correlation value, that is, a sequence generated by combining a block code and Walsh codes, and the PAPR section 1005 corresponds to each of the sequences constituting the correlation section 1003. It consists of a PAPR reduction sequence.

As shown in FIG. 10, the pilot symbol includes a first part sequence, that is, a sequence corresponding to the correlation interval 1003, and a second part sequence, that is, a sequence corresponding to the PAPR interval 1005. Here, a sequence inserted into the correlation section 1003, that is, a sequence output from the adder 207 of FIG. 2 will be referred to as a "correlation sequence". The correlation value calculation using the IFHT described with reference to FIG. 5 is performed only for the correlation section 1003.

은 길이 48의 인터리빙 방식을 나타내며, 상기

에 상응하게 상기 길이 48인 블록 코드가 인터리빙된다. 또한, 상기 도 10에서

은 왈쉬 코드 마스킹(masking)을 나타낸다. In FIG. 10, C represents a block code having a length of 48.

Denotes an interleaving scheme of length 48, and

Correspondingly, the block code of length 48 is interleaved. In addition, in FIG.

Denotes Walsh code masking.

Meanwhile, the pilot symbol is generated by a frequency domain sequence as shown in Equation 1 below.

는 짝수 인덱스를 가지는 서브 캐리 어들에만 상기 수학식 1과 같은 형태로 값이 부여되고 홀수 인덱스를 가지는 서브 캐리어들에는 무조건 0의 값이 부여되므로, IFFT 연산을 수행할 경우 시간 영역에서 동일한 시퀀스가 2회 반복되는 형태를 가지게 된다.In Equation 1, ID _cell represents a cell ID, s represents a sector ID, k represents a subcarrier index, and N _used represents the number of subcarriers actually _used in the OFDM communication system, that is, a DC component and protection. The number of subcarriers excluding the interval component is shown. In the embodiment of the present invention, it is assumed that pilot symbols of all base stations and sectors use the same frequency offset. Sequence of frequency domain as shown in Equation 1 above

Since a value is given only to subcarriers having an even index in the form of Equation 1 above, and a value of 0 is unconditionally given to subcarriers having an odd index, the same sequence in the time domain is 2 when the IFFT operation is performed. It will have a repeated form.

는 파일럿 심벌의 송신 전력 레벨이 상기 파일럿 심벌 구간 이외의 구간, 즉 데이터 심벌 구간에서 송신되는 데이터 심벌의 송신 전력 레벨과 동일한 송신 전력 레벨을 가지도록 하기 위해 설정되는 가중치이며,

은 하기 수학식 2와 같이 정의된다.In addition, in Equation 1

Is a weight set to have a transmit power level of a pilot symbol equal to a transmit power level of a period other than the pilot symbol period, that is, a data symbol transmitted in a data symbol period,

Is defined as in Equation 2 below.

은

보다 크지 않은 최대 정수를 나타낸다. 상기 수학식 2에서

은 하기 수학식 3과 같이 나타낼 수 있다. In Equation 2

silver

Represents the largest integer not greater than. In Equation 2

Can be expressed as Equation 3 below.

은 섹터 ID가 s에 해당하는 길이 8인 왈쉬 코드의 반복을 나타낸다. 또한 임의의 십진수 숫자 k(

)가

의 2 진수로 표현되고, b₆가 MSB(most significant bit)이고, b₀가 LSB(least significant bit)일 경우,

는 행 벡터(row vector)를 나타내며,

이다. 또한, 상기 수학식 3에서

은 블록 코드 생성 행렬

의 제u 열 벡터(column vector)를 나타낸다. 여기서, 상기 블록 코드 생성 행렬 G는 하기 수학식 4에 나타낸 바와 같다.In Equation 3 above

Denotes a repetition of a Walsh code of length 8 whose sector ID corresponds to s. Also, the random decimal number k (

)end

If b ₆ is the most significant bit (MSB) and b ₀ is the least significant bit (LSB),

Represents a row vector,

to be. In addition, in Equation 3

Is a block code generation matrix

Denotes the u-th column vector of. Here, the block code generation matrix G is as shown in Equation 4 below.

As shown in Equation 4, the block code generation matrix G is divided into three subblocks having a length of 16, and the positions of Walsh bases in each of the three subblocks are indicated by dotted lines. Walsh basis and mask sequences used in Equation 4 are shown in Table 2 below.                     

는

행벡터와

열벡터(column vector)의 행렬곱(matrix product)을 나타내며, 상기 행렬곱은 스칼라(scalar) 값으로 나타나는데, 이때 사용되는 연산은 modulo 2 덧셈과 곱셈이다. 상기 수학식 4에서

은 상기 도 2에서 설명한 인터리버(203)의 인터리빙 방식을 나타낸다. 상기 인터리빙 방식은 하기 표 3에 나타낸 바와 같다.Meanwhile, in Equation 4

Is

With row vector

It represents the matrix product of a column vector, which is represented by a scalar value, where the operation used is modulo 2 addition and multiplication. In Equation 4

Denotes an interleaving method of the interleaver 203 described with reference to FIG. 2. The interleaving scheme is as shown in Table 3 below.

은 상기 길이 48인 블록 코드를 구성하는 48개의 엘리먼트(element)들 각각을 상기 표 3에 나타낸 바와 같은 순서대로 그 위치를 변경(permutation)하는 것이다. 상기 표 3에서 각 숫자들은 상기 블록 코드의 엘리먼트들 각각이 일대일 매핑되는 서브 캐리어들의 인덱스들을 나타낸다.That is, the interleaving method

Is a permutation of each of the 48 elements constituting the block code of length 48 in the order shown in Table 3 above. Each number in Table 3 represents indices of subcarriers to which each of the elements of the block code is mapped one-to-one.

Looking at the interleaving scheme shown in Table 3, it can be seen that the interleaving scheme of length 16 is concatenated three times as shown in Table 4 below.                     

Each number in Table 4 represents indices of subcarriers to which elements of each of the three sub codes are mapped one to one.

의 값은 상기 파일럿 심벌의 PAPR을 최소로하는 PAPR 저감 시퀀스로 결정되는 것이다. 상기 셀 ID와 섹터 ID에 대응하는 PAPR 저감 시퀀스와, 상기 셀 ID와 섹터 ID 및 PAPR 저감 시퀀스에 상응하는 파일럿 심벌의 PAPR은 하기 표 5에 나타낸 바와 같다.In addition, the sequence in Equation 2

Is determined by a PAPR reduction sequence that minimizes the PAPR of the pilot symbol. PAPR reduction sequences corresponding to the cell ID and sector ID, and PAPR of the pilot symbols corresponding to the cell ID, sector ID and PAPR reduction sequence are shown in Table 5 below.

On the other hand, the present invention as described above can be used in the generation of a pilot symbol of an OFDM communication system using a plurality of antennas, and does not require sector division. That is, the pilot symbols transmitted through each respective antenna, for example, N _t transmit antennas in an OFDM communication system for example, a transmitter, one of the OFDM communication system using N _t transmit antennas can be expressed by Equation (5) have.

은 하기 수학식 6과 같이 정의된다. In Equation 5, n represents the number of transmit antennas, k represents a subcarrier index,

Is defined as in Equation 6 below.

역시 상기 송신안테나의 개수 N_t와 상기 OFDM 통신 시스템에서 사용하는 FFT의 크기 N_FFT에 따라 다르게 정의된다. In Equation 6, two sequences R (r) and T (k) are defined differently according to the number N _t of transmission antennas and the size N _FFT of the FFT operation used in the OFDM communication system.

It is also defined differently according to the number N _t of the transmission antennas and the size N _FFT of the _FFT used in the OFDM communication system.

에 대해서 살펴보면 다음과 같다. Here, a sequence R (r) and T (k) according to the number N _t of transmit antennas and the size N _FFT of an _FFT used in the OFDM communication system and

Looking at the following.

First, when the number of transmit antennas is two (N _t = 2) and the size of the FFT used in the OFDM communication system is 128 (N _FFT = 128), the R (r) is expressed by Equation 7 below. As shown.

In Equation 7, the block code generation matrix G is equal to Equation 4, and the interleaving scheme is shown in Table 6 below.

은 하기 표 8에 16진수로 나타낸 바와 같다.Meanwhile, T (k) of Equation 6 is as shown in Table 7 below.

Is as shown in Table 8 in hexadecimal.

Next, when the number of transmit antennas is three (N _t = 3) and the size of the FFT used in the OFDM communication system is 128 (N _FFT = 128), the R (r) is expressed by Equation 8 below. As shown in.

In Equation 8, the block code generation matrix G is shown in Equation 9 below, and the interleaving scheme is shown in Table 9 below.

은 하기 표 11에 16진수로 나타낸 바와 같다. Meanwhile, T (k) of Equation 6 is as shown in Table 10 below.

Is as shown in Table 11 in hexadecimal.

Next, when the number of transmit antennas is 4 (N _t = 4) and the size of the FFT used in the OFDM communication system is 512 (N _FFT = 512), the R (r) is represented by Equation 10 below. As shown in.

In Equation 10, the block code generation matrix G is shown in Equation 11 below, and the interleaving scheme is shown in Table 12 below.

은 하기 표 14a 내지 표 14b에 16진수로 나타낸 바와 같다. Meanwhile, T (k) of Equation 6 is as shown in Table 13 below.

Is as shown in hexadecimal in Table 14a to Table 14b.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, the present invention provides a pilot symbol for distinguishing a cell ID and a sector ID using a block code and a Walsh code in an OFDM communication system, thereby determining the number of distinguishable cell ID and sector ID in the OFDM communication system. It has the advantage of increasing. In addition, it is possible to detect the pilot symbol by using the IFHT on the receiver side has the advantage of minimizing the complexity of the receiver. In addition, by generating a pilot symbol using the block code and the Walsh code as well as the PAPR reduction sequence, the PAPR characteristic of the pilot symbol is improved.

Claims (82)

delete delete delete delete A method for transmitting a reference signal for distinguishing each of the cells in a communication system including a plurality of cells identified by a cell identifier, the method comprising: If a cell identifier is input, generating a block code corresponding to the cell identifier using a block code generation matrix; Generating a first part sequence by interleaving the block code using at least one interleaving scheme, and performing an exclusive OR on the interleaved block code; Selecting a second part sequence corresponding to the cell identifier among predefined sequences in consideration of decreasing peak-to-average power ratio; Generating a reference signal in a frequency domain using the first part sequence and the second part sequence; Converting the reference signal in the frequency domain into an inverse fast Fourier transform into a reference signal in the time domain; And transmitting a reference signal of the time domain in a reference signal transmission section. The method of claim 5, The process of converting to the reference signal in the time domain, Inserting null data into each of the subcarriers corresponding to the DC component among the N subcarriers and the interference cancellation component between the N subcarriers; Inserting each of the elements constituting the reference signal in the frequency domain into each of the M subcarriers other than the subcarriers into which the null data is inserted among the N subcarriers; And performing an inverse fast Fourier transform on the signal including the elements and the M subcarriers, and then transmitting the signal. The method of claim 6, And inserting each of the elements constituting the reference signal in the frequency domain using an offset differently set for the cells and each of the sectors constituting each of the cells. delete The method of claim 6, The reference signal of the frequency domain is a reference signal transmission method, characterized in that represented by the following equation. ≪ Equation &

here,

Represents a reference signal in the frequency domain, ID _cell represents the cell identifier, s represents a sector identifier, k represents a subcarrier index, N _used is the same value as M, the number of subcarriers, and N _FFT is inverse Indicates the number of points of a fast Fourier transform operation,

Indicates the setting sequence. 10. The method of claim 9, The setting sequence is, A reference signal transmission method characterized by the following equation. ≪ Equation &

here,

silver

Represents the largest integer not greater than,

Is the same as ≪ Equation &

here,

Denotes a code in which a Walsh code of length 8 corresponding to the sector identifier s is repeated a predetermined number of times, k denotes a value calculated by adding a cell identifier and 1,

(only,

) Represents the k-th row vector of the block code generation matrix,

(

) Represents the u th column vector of the block code generation matrix, and u represents the interleaving scheme.

The r-th element of the interleaving pattern according to R, denotes the first part sequence, and T () denotes the second part sequence. The method of claim 10, The block code generation matrix is A reference signal transmission method characterized by the following equation. ≪ Equation &

The method of claim 11, When the N _used is 108, the interleaving scheme

The reference signal transmission method, characterized in that determined in the manner as shown in the following table.

Wherein each number represents indices of subcarriers to which each of the elements of the block code is mapped one-to-one. An apparatus for transmitting a reference signal for distinguishing each of the cells in a communication system including a plurality of cells identified by a cell identifier, A block code encoder for generating a block code corresponding to the cell identifier using a block code generation matrix when a cell identifier is input; An interleaver for interleaving the block code using at least one interleaving scheme; An adder for generating a first part sequence by performing an exclusive OR on the Walsh code repeated to the interleaved block code; A combiner for generating a reference signal in a frequency domain using the first part sequence and a second part sequence selected corresponding to the cell identifier among predetermined sequences; And a transmitter for transmitting a reference signal in the time domain after converting the reference signal in the frequency domain into a reference signal in the time domain in a predetermined reference signal transmission period. The method of claim 13, The block code generation matrix is A preset b subblocks, each of the b subblocks including c Walsh basis and d mask sequences, wherein the b subblocks mutually maximize each other to maximize the minimum distance of the block code. And a first sub block to a b sub block having a cyclic shift relationship. delete The method of claim 14, The interleaver, And dividing the block code into b subcodes, and interleaving each of the b subcodes using each of the b interleaving schemes differently set. The method of claim 13, The transmitter; Null data is inserted into each of the subcarriers corresponding to the DC component among the N subcarriers and the interference cancellation component between the N subcarriers, and other than the subcarriers into which the null data is inserted among the N subcarriers. Inserting each of the elements constituting the reference signal in the frequency domain into each of the M subcarriers, and performing an inverse fast Fourier transform on the elements constituting the reference signal in the frequency domain and a signal including the M subcarriers With a fast Fourier transformer, And a radio frequency processor for radio frequency processing and transmitting the inverse fast Fourier transformed signal. The method of claim 13, The transmitter; Null data is inserted into each of the subcarriers corresponding to the DC component among the N subcarriers and the interference cancellation component between the subcarriers, and the null data of the N subcarriers is inserted using a predefined offset. Insert each of the elements constituting the reference signal in the frequency domain into each of the M subcarriers other than the subcarriers, and invert the signal including the elements constituting the reference signal in the frequency domain and the M subcarriers. An inverse fast Fourier converter to convert fast Fourier, And a radio frequency processor for radio frequency processing and transmitting the inverse fast Fourier transformed signal. The method of claim 18, The offset is, And a set value different for each of the cells and the sectors constituting each of the cells. The method of claim 17, The reference signal in the frequency domain, Reference signal transmission apparatus, characterized in that defined by the following equation. ≪ Equation &

here,

Represents a reference signal in the frequency domain, ID _cell represents the cell identifier, s represents a sector identifier, k represents the subcarrier index, N _used is the same value as M, the number of subcarriers,

Indicates the setting sequence. 21. The method of claim 20, The setting sequence is, Reference signal transmission apparatus, characterized in that expressed as the following equation. ≪ Equation &

here,

silver

Represents the largest integer not greater than,

Is defined as ≪ Equation &

here,

Denotes a code in which a Walsh code of length 8 corresponding to sector identifier s is repeated a predetermined number of times, k denotes a value calculated by adding the cell identifier and 1,

(only,

) Represents the k-th row vector of the generation matrix of the block code,

(

) Represents the u th column vector of the block code generation matrix, and u represents the interleaving scheme.

Where r () represents the r-th element of the living pattern, R () represents the first part sequence, and T () represents the second part sequence. The method of claim 21, The block code generation matrix is Reference signal transmission apparatus, characterized in that expressed as the following equation. ≪ Equation &

The method of claim 22, When the N _used is 108, the

Reference signal transmission apparatus, characterized in that determined in the manner as shown in the following table. <Table>

Here, each number represents an index of a subcarrier to which each of the elements of the block code is mapped one to one. Including a plurality of cells separated by cell identifiers In a communication system, a method for receiving a reference signal for distinguishing each of the plurality of cells, Extracting a reference signal from the fast Fourier transformed received signal, Dividing the reference signal by a predetermined interval unit and performing exclusive OR on the divided signals and the repeated Walsh code; Deinterleaving the exclusive OR signal using at least one deinterleaving scheme; Dividing the deinterleaved signal into sub-block signals using a block code generation matrix; Performing inverse fast Hadamard transform using each of the mask sequences on each of the subblock signals; Generating a combined signal by combining the inverse fast Hadamard transformed signals; And detecting a cell identifier corresponding to a block code having a maximum correlation value among combined signals corresponding to each of the plurality of cell identifiers as a final cell identifier. The method of claim 24, Extracting the reference signal; Receiving a reference signal comprising the step of removing a predefined sequence from the signal received through the M sub-carriers other than the sub-carriers corresponding to the DC component of the N sub-carriers and the interference cancellation component between the N sub-carriers Way. The method of claim 25, The process of removing, And performing offset using different offsets for the cells and each of the sectors constituting each of the cells. delete The method of claim 26, The reference signal is a reference signal receiving method, characterized in that defined in the frequency domain as shown in the following equation. &Lt; Equation &

here,

Denotes a reference signal in the frequency domain, ID _cell denotes the cell identifier, s denotes a sector identifier, k denotes a subcarrier index, N _FFT denotes the number of points of an FFT operation, and N _used denotes a sub Is equal to M, the number of carriers,

Indicates the setting sequence. The method of claim 28, The setting sequence is, Reference signal receiving method characterized in that expressed as the following equation. &Lt; Equation &

here,

silver

Represents the largest integer not greater than,

Is the same as &Lt; Equation &

here,

Denotes a code in which a Walsh code having a length of 8 corresponding to the sector identifier s is repeated a predetermined number of times,

(only,

) Represents a k-th row vector of the block code generation matrix, k represents a value calculated by adding the cell identifier and 1,

(

) Represents a u-th column vector of the block code generation matrix, and u represents a deinterleaving scheme.

Represents the r-th element of the interleaving pattern according to. 30. The method of claim 29, The block code generation matrix is Reference signal receiving method characterized in that expressed as the following equation. &Lt; Equation &

30. The method of claim 29, When the N _used is 108

The reference signal receiving method, characterized in that determined in the manner as shown in the following table. <Table>

Here, each number represents an index of a subcarrier to which each of the elements of the block code is mapped one to one. The method of claim 31, wherein The setting sequence is a reference signal receiving method, characterized in that the peak to average power ratio for the reference signal is set to a sequence having a minimum value. In a communication system including a plurality of cells separated by a cell identifier, an apparatus for receiving a reference signal for distinguishing each of the plurality of cells, A fast Fourier transformer for converting a received signal to a fast Fourier transform, A reference signal extractor for extracting a reference signal from the fast Fourier transformed signal; An adder for dividing the reference signal into units of a predetermined number of preset intervals and performing an exclusive OR on the Walsh code repeated to the divided signals; A deinterleaver for deinterleaving the exclusive OR signal using at least one deinterleaving scheme; A sub block divider for dividing the deinterleaved signal into sub block signals corresponding to a predetermined block code generation matrix; A block code decoder for inverse fast Hadamard transform using each of the mask sequences for each of the sub-block signals; A combiner for combining the inverse fast Hadamard transformed signals; And a comparison selector for detecting a cell identifier corresponding to a block code having a maximum correlation value among combined signals corresponding to each of the plurality of cell identifiers as a final cell identifier. 34. The method of claim 33, The reference signal extractor, And extracting a predetermined sequence from a signal received through M subcarriers other than the subcarriers corresponding to the DC component among the N subcarriers and the interference cancellation component between the subcarriers, thereby extracting the reference signal. Reference signal receiving device. The method of claim 34, wherein The reference signal extractor, And extracting the reference signal using offsets differently set for the cells and the sectors constituting each of the cells. delete 36. The method of claim 35 wherein The reference signal receiving apparatus, characterized in that expressed in the following equation in the frequency domain. &Lt; Equation &

here,

Represents a reference signal in the frequency domain, ID _cell represents the cell identifier, s represents a sector identifier, k represents a subcarrier index, N _used is the same value as M, the number of subcarriers, and N _FFT is Indicates the number of points in the FFT operation,

Indicates the setting sequence. The method of claim 37, The setting sequence is, Reference signal receiving apparatus characterized in that expressed as the following equation. &Lt; Equation &

here,

silver

Represents the largest integer not greater than,

Is defined as &Lt; Equation &

here,

Denotes a code in which a Walsh code having a length of 8 corresponding to the sector identifier s is repeated a predetermined number of times,

(only,

) Represents a k-th row vector of the generation matrix of the block code, k represents a value calculated by adding the cell identifier and 1,

(

) Represents the u th column vector of the block code generation matrix, and u represents the deinterleaving scheme.

Represents the r-th element of the interleaving pattern according to. 39. The method of claim 38, The block code generation matrix is Reference signal receiving apparatus characterized in that expressed as the following equation. &Lt; Equation &

The method of claim 37, When the N _used is 108, the

Reference signal receiving apparatus, characterized in that determined in the manner as shown in the following table. <Table>

Here, each number represents an index of a subcarrier to which each of the elements of the block code is mapped one-to-one. 39. The method of claim 38, The setting sequence is, And a peak-to-average power ratio for the reference signal is set in a sequence having a minimum value. In a communication system including a plurality of cells separated by a cell identifier, a method for transmitting a reference signal for distinguishing each of the plurality of cells through at least one transmitting antenna, Receiving a cell identifier, Generating a block code corresponding to the cell identifier using a block code generation matrix, selecting a Walsh code corresponding to the cell identifier among predefined Walsh codes, and repeating the predetermined number of times; Interleaving the block code in at least one interleaving scheme, and generating an first part sequence by performing exclusive OR on the interleaved block code and the repeated Walsh code; Selecting a second part sequence corresponding to the cell identifier among predefined sequences; Generating a reference signal in a frequency domain using the first part sequence and the second part sequence; And converting the reference signal of the frequency domain into an inverse fast Fourier transform to a reference signal of the time domain, and then transmitting the reference signal of the time domain in a predefined reference signal transmission interval. The method of claim 42, wherein The block code generation matrix is and b subblocks, wherein each of the b subblocks consists of c Walsh basis and d mask sequences. The method of claim 43, Each of the b sub-blocks includes a first sub block to a b sub block having a cyclic shift relationship therebetween to maximize a minimum distance of the block code generated using the block code generation matrix. A reference signal transmission method. The method of claim 43, Interleaving the block code in the interleaving scheme; Dividing the block code into b subcodes; Interleaving using each of the b interleaving schemes differently set for each of the b subcodes. The method of claim 45, Inverse fast Fourier transform the reference signal in the frequency domain; Null data is inserted into each of the subcarriers corresponding to the DC component among the N subcarriers and the interference cancellation component between the N subcarriers, and other than the subcarriers into which the null data is inserted among the N subcarriers. And inserting each of the elements constituting the reference signal in the frequency domain into each of the M subcarriers of the inverse fast Fourier transform. The method of claim 45, Inverse fast Fourier transform the reference signal in the frequency domain; Insert null data into each of the subcarriers corresponding to a DC component among the N subcarriers and an interference cancellation component between the N subcarriers, and use the predefined offset and the null data of the N subcarriers. And inserting each of the elements constituting the reference signal into each of the M subcarriers other than the inserted subcarriers, and then transmitting by inverse fast Fourier transform. 49. The method of claim 47, The offset is, And a different value for each of the cells and the sectors constituting the cells. 47. The method of claim 46 wherein The reference signal in the frequency domain, A reference signal transmission method, characterized in that defined as the following equation. &Lt; Equation &

here,

Denotes a reference signal in the frequency domain, ID _cell denotes the cell identifier, n denotes the number of transmit antennas, k denotes the subcarrier index, and N _FFT denotes the points of the inverse fast Fourier transform operation. N _used represents the number of subcarriers, N _t represents the number of transmit antennas, and

Indicates the setting sequence. The method of claim 49, The setting sequence is, A reference signal transmission method characterized by the following equation. &Lt; Equation &

here,

silver

The largest integer not greater than, R () represents the first part sequence, and T () represents the second part sequence. 51. The method of claim 50, remind

silver, A reference signal transmission method characterized by the following equation. &Lt; Equation &

Here, the number of transmit antennas is two, the size of the fast Fourier transform operation is 128,

(

) Represents the u th column vector of the block code generation matrix, and u represents the interleaving scheme.

Represents the r-th element of the interleaving pattern according to. The method of claim 51, The block code generation matrix is A reference signal transmission method characterized by the following equation. &Lt; Equation &

The method of claim 51, remind

silver, The reference signal transmission method, characterized in that determined in the manner as shown in the table below. <Table>

Here, each number represents an index of a subcarrier to which each of the elements of the block code is mapped one-to-one. 51. The method of claim 50, The T (k) is a reference signal transmission method, characterized in that determined in the manner as shown in the following table. <Table>

51. The method of claim 50, remind

The reference signal transmission method, characterized in that determined in the manner as shown in the following table. <Table>

51. The method of claim 50, remind

silver, A reference signal transmission method characterized by the following equation. &Lt; Equation &

Here, the number of transmit antennas is three, and the size of the fast Fourier transform operation is 128,

(

) Represents a u th column vector of the block code generation matrix, and u is an interleaving scheme.

Represents the r-th element of the interleaving pattern according to. The method of claim 56, wherein The block code generation matrix is A reference signal transmission method characterized by the following equation. &Lt; Equation &

The method of claim 56, wherein remind

silver, The reference signal transmission method, characterized in that determined in the manner as shown in the table below. <Table>

Here, each number represents a subcarrier index to which each of the elements of the block code is mapped one-to-one. The method of claim 51, The T (k) is, The reference signal transmission method, characterized in that determined in the manner as shown in the table below. <Table>

51. The method of claim 50, remind

The reference signal transmission method, characterized in that determined in the manner as shown in the following table. <Table>

The method of claim 60, remind

silver, A reference signal transmission method characterized by the following equation. &Lt; Equation &

Here, the number of transmit antennas is four, the size of the fast Fourier transform operation is 512,

(

) Represents a u th column vector of the block code generation matrix, and u is an interleaving scheme.

Represents the r-th element of the interleaving pattern according to. 62. The method of claim 61, The block code generation matrix is A reference signal transmission method characterized by the following equation. &Lt; Equation &

62. The method of claim 61, remind

silver, The reference signal transmission method, characterized in that determined in the manner as shown in the table below. <Table>

Here, each number represents a subcarrier index to which each of the elements of the block code is mapped one-to-one. 62. The method of claim 61, The T (k) is, The reference signal transmission method, characterized in that determined in the manner as shown in the table below. <Table>

51. The method of claim 50, remind

The reference signal transmission method, characterized in that determined in the manner as shown in the following table. <Table>

A method for providing a pilot symbol for base station identification in a multiple input multiple output communication system including one or more transmit antennas, the method comprising: Generating a pilot symbol; And the pilot symbol comprises a first part sequence having cell discrimination characteristics and a second part sequence having reduced peak to average power ratio characteristics for all pilot symbols. The method of claim 66, The first part sequence is, Generated by block coding information to be transmitted by the base station to the terminal; The information to be transmitted by the base station to the terminal, the pilot symbol providing method characterized in that it comprises a cell identifier. The method of claim 66, The second part sequence is, And generating the second part sequence in consideration of a first part sequence of a predefined reference table. The method of claim 67, And when the number of transmit antennas is 2 and the size of the fast Fourier transform operation is 128, the first part sequence is defined by the following equation. &Lt; Equation &

Where R () represents the first part sequence,

silver

Represents a maximum integer not greater than, and ID _cell represents a cell identifier. The method of claim 66, The pilot symbol is, A pilot symbol providing method characterized by the following equation.  &Lt; Equation &

Where R () represents the first part sequence, T () represents the second part sequence, N _used represents the number of subcarriers actually _used in the multiple input multiple output communication system, and N _t represents Indicate the number of the transmitting antenna. delete delete delete delete delete delete delete delete delete delete delete delete

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