KR100899139B1 - Receiver for Frame Synchronization in Wireless Communication Systems and Method thereof - Google Patents

Abstract

The present invention relates to a receiving apparatus and method using a wireless communication system based FFT, and to provide a receiving apparatus and method using a wireless communication system based FFT using a fast Fourier transform to reduce the computational complexity of the receiving end for frame synchronization. will be.

The technical configuration includes an RF processor for down-converting a frequency band by receiving a frame transmitted in an RF band by a wireless communication system based transmitter; An A / D converter converting the received frame into digital; A differential correlation unit for converting a time domain differential correlation operation between a reference signal of the frame converted by the A / D converter and a received signal to which a time error is applied to a multiplication operation of a frequency domain using an FFT module; An amplitude correlation unit for performing amplitude correlation between the reference signal of the frame converted by the A / D converter and the received signal using a moving sum to reduce the amount of calculation; A summing unit for summing a difference between an output of the differential correlation unit and an output of an amplitude correlation unit; A maximum value detector for estimating the time error; Characterized in that it comprises a.

Wireless Communications, Multiple Differential Detection, Frame Sync, Frequency Error, Offset, FFT, DFT

Description

Receiver and Frame Synchronization in Wireless Communication Systems and Method

1 is a block diagram schematically showing a frame according to the present invention;

2 is a block diagram schematically illustrating a wireless communication system to which a receiving apparatus using a FFT based on a wireless communication system according to the present invention is applied.

3 is a flowchart schematically illustrating a driving process of a wireless communication system to which a receiving method using a wireless communication system based FFT according to the present invention is applied.

4 is a block diagram schematically illustrating a receiving apparatus using a FFT based on a wireless communication system according to the present invention.

5 is a flowchart schematically illustrating a receiving method using a wireless communication system based FFT according to the present invention.

Figure 6a is a receiver according to the prior art for comparison with a receiver using a wireless communication system based FFT according to the present invention.

6B is a block diagram schematically illustrating a receiving apparatus using a FFT based on a wireless communication system according to the present invention.

7 is a diagram illustrating a comparison of the size of the FFT and a peak value according to the size of the FFT of the receiving apparatus using the FFT based on the wireless communication system according to the present invention.

8 is a diagram illustrating a comparison of the FFT size of a reception apparatus using a FFT based on a wireless communication system according to the present invention.

FIG. 9 is a diagram illustrating a calculation according to time of a receiving apparatus using a wireless communication system based FFT according to the present invention and a receiving apparatus according to the prior art. FIG.

FIG. 10 is a graph illustrating a comparison of a complex product operation according to a preamble size of a differential correlation unit in a reception apparatus using a wireless communication system-based FFT according to the present invention.

FIG. 11 is a graph illustrating a comparison of a real product according to a preamble size of an amplitude correlation unit in a reception apparatus using a wireless communication system based FFT according to the present invention.

12 is a graph illustrating an error recognition rate according to a reception apparatus using a FFT based on a wireless communication system according to the present invention in comparison with the related art.

The present invention relates to a receiving apparatus and method using a wireless communication system-based FFT, and to reduce the computational complexity of the receiver for frame synchronization by changing the operation of the time domain to the operation of the frequency domain using a fast Fourier transform. The present invention relates to a receiver and a method using a base FFT.

 In general, a wireless communication system (Wireless Communication System) is a system that supports wireless communication, composed of a base station (BS) and a mobile station (MS).

In addition, since the base station and the mobile station support the wireless communication service using the frame, the base station and the mobile station must acquire mutual synchronization for transmitting and receiving the frame. Should be sent.

In order to obtain such synchronization, the wireless communication system detects a frame start time of the received signal, and transmits a preamble at the front end of the frame.

In addition, the preamble is a signal promised between the transmitting and receiving end, and the receiving end performs frame synchronization for detecting the start time of the frame by using a correlation pattern between the received signal and the existing signal.

However, in a wireless communication environment, the transmitted signal is distorted in various forms during the transmission process, such as reflected waves, diffraction waves, other noises, and multipath interference caused by high-rise buildings, and frequency errors due to oscillator mismatch between the transmitting and receiving ends. The ML-based multiple differential detection method has a high complexity of the receiver, and performs a high complexity correlation that is proportional to the size of the preamble in every sample unit. As a result, the unit cost increases and power consumption increases. This is a problem, which is inadequate for frame synchronization in a low power and low cost wireless communication system.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. It is an object to provide a receiving apparatus and method used.

Another object of the present invention is to provide a receiving apparatus and method using a wireless communication system based FFT that can reduce the complexity of the receiving end to implement frame synchronization of a low cost, low power wireless communication system.

In order to achieve the above object, the present invention provides an RF processing unit for down-converting a frequency band by receiving a frame transmitted in an RF band by a wireless communication system based transmitter; An A / D converter converting the received frame into digital; A differential correlation unit for converting a time domain differential correlation operation between a reference signal of the frame converted by the A / D converter and a received signal to which a time error is applied to a multiplication operation of a frequency domain using an FFT module; An amplitude correlation unit for performing amplitude correlation between the reference signal of the frame converted by the A / D converter and the received signal using a moving sum to reduce the amount of calculation; A summing unit for summing a difference between an output of the differential correlation unit and an output of an amplitude correlation unit; A maximum value detector for estimating the time error; It includes.

The FFT module of the differential correlation unit converts a reference signal and a received signal into a frequency domain through a discrete Fourier transform.

Here, the differential correlation operation between the reference signal and the received signal converted into the frequency domain may be changed into a multiplication operation of the frequency domain.

The reference signal and the received signal of the frequency domain, which are differentially correlated by the product of the frequency domain, are converted into the reference signal and the received signal of the time domain by a discrete Fourier inverse transform of the inverse FFT module.

The differential correlator may include a first delayer configured to delay the received signal for a predetermined time; A conjugate complexer which conjugate-complexes the received signal of the first delayer; A first multiplier outputting a differential signal between the received signal and a reference signal through a complex product of the output of the A / D converter and the output of the conjugate complexer; An FFT module for converting the differential signal into a frequency domain with discrete Fourier transform for differential correlation operation; A frequency domain multiplier for multiplying the differential signal in a frequency domain by the FFT module; An inverse FFT module for performing a discrete Fourier inverse transform on the differential correlation operation computed by the frequency domain multiplier to transform into a time domain; A first absolute value operator for absolute value processing the result output by the inverse FFT module; It includes.

In addition, a correlation output value for the preamble samples of the plurality of frames may be calculated by frequency domain computation of the FFT module, the frequency domain multiplier, and the inverse FFT module.

Here, the size of the FFT module and the inverse FFT module is twice the size of the preamble of the frame.

At this time, the differential correlation unit is characterized in that the complex multiplication amount is reduced by the FFT module, frequency domain multiplier, inverse FFT module.

The amplitude correlator may further include: a second delayer configured to delay the output of the A / D converter for a predetermined time; A second absolute value calculator for absolute value processing the output of the A / D converter; A third absolute value calculator for absolute value processing the output of the second delayer; A second multiplier for multiplying outputs of the second absolute value calculator and the third absolute value calculator; A move adder for calculating the output of the second multiplier by a move adder; It includes.

Here, the amplitude correlation unit is characterized in that the real product calculation amount is reduced by the mobile summation method of the mobile adder.

In this case, the amount of frame synchronization is reduced by a complex product operation of the differential correlation unit and a real product operation of the amplitude correlation unit.

On the other hand, a first step of receiving a frame transmitted in the RF band by the wireless communication system based transmitter to down-convert the frequency of the signal in the RF processing unit, and converts it to a digital signal in the A / D converter; A second step of calculating, by the differential correlator, a differential correlation operation of a time domain between a reference signal and a received signal to which a time error is applied as a product of a frequency domain using an FFT module; A third step of moving and adding the reference signal and the received signal of the frame converted by the A / D converter so that the amount of calculation is reduced in an amplitude correlation unit; A fourth step of estimating a time error for frame synchronization in the maximum value detector by summing a difference between an output of the differential correlator and an output of an amplitude correlator; It is made, including.

Here, the step 2 is characterized in that the FFT module of the differential correlator converts the reference signal and the received signal into Fourier transforms into a frequency domain.

The differential correlation operation between the reference signal and the received signal converted into the frequency domain may be changed by a multiplication operation of the frequency domain.

The reference signal and the received signal of the frequency domain, which are differentially correlated by the product of the frequency domain, are converted into the reference signal and the received signal of the time domain by a discrete Fourier inverse transform of the inverse FFT module.

Hereinafter, according to the present invention Example  It will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically showing a frame according to the present invention. As shown in the figure, as shown in the figure, a frame according to the present invention comprises a preamble and data.

The preamble includes information on a frame and the like to find a starting point in frame synchronization. The preamble is disposed in front of the frame and transmitted.

In addition, the preamble or data is modulated by a single carrier, but can be modulated by an orthogonal frequency division multiplexing (OFDM).

2 is a block diagram schematically illustrating a wireless communication system to which a reception apparatus using a wireless communication system based FFT according to the present invention is applied, and FIG. 3 is a radio to which a receiving method using a wireless communication system based FFT according to the present invention is applied. A flowchart schematically illustrating a driving process of a communication system.

As shown in the drawing, a wireless communication system includes a multiplexer, a transmitter, a transmit antenna (TX antenna), a receive antenna (RX antenna), and a receiver (Receiver), to which a frame is input. And a demultiplexer.

Here, a multiplexing device (multiplexer) is a device capable of dividing a single line or transmission line using a multiplexing technique and transmitting and receiving a plurality of independent signals. Scheme (FDM), time division multiple scheme (TDM), code division multiple scheme (CDM), and the like.

The reference signal and the data signal are simultaneously input and transmitted to the multiplexer for synchronization between the transmitter and the receiver. The reference signal and the data signal are arranged and integrated in a predetermined order and position by the multiplexer.

In addition, the transmitter spreads the integrated signal, loads the signal on a carrier, amplifies the signal, and sends the signal to a transmitting antenna, which amplifies the radio frequency to a receiving antenna and transmits the frequency to the receiving antenna. Up-convert and transmit on the radio channel through the transmit antenna.

The receiver 1 down-converts a radio frequency, which is a frequency up-converted by the transmitter, to an intermediate frequency (IF) or a base band.

In addition, an original signal is generated by despreading the signal spread by the transmitting apparatus, and the code used when spreading by the transmitting apparatus must be known exactly, which is used for synchronization.

 Also, a demultiplexer is a combinational logic circuit that performs the opposite function of the multiplexer, and is also called a divider because it selects one of a plurality of outputs and connects the inputs.

For example, the 1 / N demultiplexer has one input and 2N outputs, and preferably has N select lines for selecting one of the 2N output lines.

Hereinafter, an operation process of the wireless communication system according to the present embodiment will be described.

First, a data signal and a reference signal, which is a reference that can be compared with the data signal, are input for frame synchronization in a multiplexing apparatus of a wireless communication system based transmitter.

In addition, in the multiplexing apparatus, the reference signal and the data signal are arranged in a predetermined order and position for synchronization between the transmitting and receiving terminals, integrated, and transmitted to the transmitting apparatus (S10).

In addition, the transmitting apparatus is configured to spread and modulate the signals for frame synchronization, adjust the frequency upward to use a radio band in an RF band, and amplify the signal through a transmitting antenna to receive the wireless communication system based receiver. Transfer to step (1) (S20).

In addition, the reception device 1 down-converts the frequency up-converted to RF in the transmission device to IF or baseband, converts the analog signal to digital for digital signal processing, and reverses the signal spread in the transmission device. A demodulation process of spreading and restoration is performed and transmitted to the demultiplexing apparatus S30.

In this case, the demultiplexing apparatus separates and outputs a signal into data, a control signal, and the like (S40).

4 is a block diagram schematically illustrating a receiving apparatus using a wireless communication system based FFT according to the present invention, and FIG. 5 is a flowchart schematically showing a receiving method using a wireless communication system based FFT according to the present invention.

As shown in the figure, the receiving device 1 using the wireless communication system-based FFT according to the present invention is the RF processor 10, the A / D converter 20, the differential correlator 30 and the amplitude correlation unit 40, an adder 50, and a maximum value detector 50.

In this case, the RF processor 10 down-converts a radio frequency, which is an frequency up-converted by the transmitting apparatus, to an intermediate frequency (IF) or a base band.

The A / D converter 20 processes a signal having a frequency down-converted by the RF processor 10 (DSP: Digital Signal Process), and converts an analog signal into a digital signal. Convert it to a signal.

The differential correlator 30 may include a first delay unit (Delay 1, 31), a conjugate complex (32), a first multiplier (33), an FFT module (34), and a frequency domain multiplier. And an inverse FFT module 36 and a first absolute value calculator 37.

Here, the digital signal output from the A / D converter 20 is time-delayed in the first delay unit 31, passes through the conjugate complexer 32, and the signal output from the conjugate complexer 32. The signal output from the A / D converter 20 is input to the first multiplier 33.

The first multiplier 33 performs a multiplication operation, but performs a complex multiplication operation due to the complex value output through the conjugate complexer 32.

In addition, the FFT module 34 is a differential signal between the reference signal and the received signal output from the first multiplier 33 is a discrete Fourier operation of the FFT module 34, the reference signal and the received signal in the frequency domain (Frequency Domain) Is converted into a differential signal.

The frequency domain multiplier 35 is similar to a multiplier in the time domain, but differs in that it multiplies the signals in the frequency domain, and differs in that it changes the correlation operation into a multiplication operation.

Accordingly, a discrete Fourier inverse transform (IDFT) is performed to multiply the differential signal of the reference signal and the received signal and convert it back to the time domain, which is performed by the inverse FFT module 36.

The signal output from the inverse FFT module 36 is subjected to absolute value processing through the first absolute value calculator 37 and output.

In addition, the amplitude correlator 40 may include a second delayer 41, a second absolute value calculator 42, a third absolute value calculator 43, a second multiplier 44, and a moving totalizer ( 45).

The signal input to the amplitude correlator 40 is a digital signal output from the A / D converter 20, which is input together to the second absolute value calculator 42.

The digital signal input to the amplitude correlator 40 is input to the second delay unit 41 and passes through a third absolute value calculator 43 that gives a predetermined time delay to the digital signal and processes the absolute value.

In addition, the values output from the third absolute value calculator 43 and the second absolute value calculator 42 are multiplied by the second multiplier 44, and the amplitude (magnitude) of the received signal and the time delayed signal. Correlate between amplitude (magnitude).

Here, the signal output from the second multiplier 44 is moved to the moving summer 45 to reduce the complexity of the amplitude correlation by using the moving summery method.

The adder 50 adds a difference between the output value of the amplitude correlation unit 40 and the output value of the differential correlation unit 30.

In addition, the maximum detector 60 estimates an error with respect to a time delay and demodulates the data using the maximum detector 60.

Hereinafter, a reception process using a wireless communication system based FFT according to the present invention will be described.

First, a reference signal and a received signal are received from the transmitter, and are down-converted from the RF band to the IF band or the base band band (S30-1).

In operation S30-2, the A / D converter converts the analog signal into a digital signal for digital signal processing (DSP).

In addition, the differential correlation unit converts the operation of the differential reference signal and the differential receive signal into the frequency domain through the FFT module and the inverse FFT module, thereby reducing the amount of calculation. The discrete Fourier transform is used in the FFT and the discrete FFT module is used. Fourier inverse transform is used (S30-3).

In addition, instead of outputting a correlation operation value for each sample, a correlation operation of a predetermined number, for example, N samples may be output at a time, thereby reducing the amount of calculation.

On the other hand, the amplitude correlation unit performs amplitude correlation to reduce the amount of calculation using the moving summation method of the received signal amplitude and the delayed received signal amplitude output from the A / D converter (S30-4).

Then, the output value of the amplitude correlation unit is differentially summed from the output value of the differential correlator (S30-5), and the maximum time error is estimated for data demodulation among the time errors output from the summing unit in the maximum value detector. Upon completion, the time error is used for data demodulation (S30-6).

Figure 6a is a receiving device according to the prior art for comparison with a receiving device using a wireless communication system based FFT according to the present invention, Figure 6b schematically shows a receiving device using a wireless communication system based FFT according to the present invention It is a block diagram.

As shown in the figure, the receiver 1 using the wireless communication system-based FFT according to the present invention has a correlation unit of the receiver according to the prior art FFT module 34, frequency domain multiplier 35 and inverse FFT module It is changed to 36.

Here, the output value of the differential correlator of FIG. 6A is calculated as follows.

First, the RF processor and the A / D converter down-convert the radio frequency, which is the frequency up-converted by the transmitter, to the IF or baseband, and convert the digital frequency into a digital signal for the DSP.

At this time, a time delay is added to the received signal, which is a digital signal, and accordingly a correlation operation is performed on the signal output from the delayer and the conjugate complexer and the signal output from the A / D converter.

And, the absolute value is processed and output, the differential correlator output value according to the prior art is shown in the following equation (1).

Here, N denotes the size of the preamble, s ₁ ^* [n] and r ₁ [n] denote differential signals of a reference signal and a received signal, respectively, and τ denotes a time delay.

On the other hand, the output value of the differential correlator of FIG. 6B is calculated as follows.

First, the RF processor 10 down-converts a radio frequency, which is a frequency up-converted by the transmitter, to an intermediate frequency (IF) or a base band.

The A / D converter 20 processes a signal having a frequency down-converted by the RF processor 10 (DSP: Digital Signal Process), and converts an analog signal into a digital signal. Convert it to a signal.

Here, the digital signal output from the A / D converter 20 is time-delayed in the first delay unit 31, passes through the conjugate complexer 32, and the signal output from the conjugate complexer 32. The signal output from the A / D converter 20 is input to the first multiplier 33.

The first multiplier 33 performs a multiplication operation, but performs a complex multiplication operation due to the complex value output through the conjugate complexer 32.

In addition, the FFT module 34 is a differential signal between the reference signal and the received signal output from the first multiplier 33 is a discrete Fourier operation of the FFT module 34, the reference signal and the received signal in the frequency domain (Frequency Domain) Is converted into a differential signal, which is expressed by Equation 2 below.

The frequency domain multiplication is performed similar to the multiplier in the time domain, except that the signals in the frequency domain are multiplied, and the correlation is changed to multiplication.

The operation on the frequency domain multiplication is expressed by Equation 3 below.

Here, N denotes the size of the preamble, S ₁ ^* [n] and R ₁ [n] denote differential signals of a reference signal and a received signal, respectively, and τ denotes a time delay.

In addition, a discrete Fourier inverse transform (IDFT) is performed to multiply the differential signal of the reference signal and the received signal and convert it back to the time domain, which is performed by the inverse FFT module 36. Same as

The signal output from the inverse FFT module 36 is subjected to absolute value processing through the first absolute value calculator 37 and output.

In the reception apparatus 1 using the wireless communication system-based FFT according to the present invention, the correlation unit of the reception apparatus according to the prior art is changed to the mobile summer 45.

Here, the output value of the amplitude correlator of FIG. 6A is calculated as follows.

First, the digital signal output from the A / D converter is input to the second delay unit to give a predetermined time delay to the digital signal, and passes through a plurality of arithmetic units for absolute value processing.

Then, a correlation between the amplitude (magnitude) of the received signal and the amplitude (magnitude) of the time delayed signal is performed and the output signal passes through a correlator, which is expressed by Equation 5 below.

On the other hand, the output value of the amplitude correlator of FIG. 6B is calculated as follows.

First, the signal input to the amplitude correlator 40 is a digital signal output from the A / D converter 20, which is input together to the second absolute value calculator 42.

The digital signal input to the amplitude correlator 40 is input to the second delay unit 41 and passes through a third absolute value calculator 43 that gives a predetermined time delay to the digital signal and processes the absolute value.

In addition, the values output from the third absolute value calculator 43 and the second absolute value calculator 42 are multiplied by the second multiplier 44, and the amplitude (magnitude) of the received signal and the time delayed signal. Correlate between amplitude (magnitude).

Here, the signal output from the second multiplier 44 is moved to the moving summer 45 to reduce the complexity of the amplitude correlation by using the moving summery method.

Therefore, the output value of the amplitude correlation unit 40 is as shown in Equation 6 below.

7 is a diagram illustrating a comparison of FFT sizes and peak values according to FFT sizes in a reception apparatus using a wireless communication system based FFT according to the present invention, and FIG. 8 is a diagram illustrating reception using a wireless communication system based FFT according to the present invention. This is a diagram comparing the FFT size of the device.

As shown in the figure, FIG. 7 illustrates a case in which the size of the FFT is formed to be the same as the preamble.

(A) is τ = 0, and the maximum correlation value of the differential reference signal (DPS) and the differential received signal (DRS) appears without error.

(B) is a case where τ ≠ 0, and a part of the differential received signal is excluded from the FFT interval, causing a decrease in the maximum correlation value, and a decrease in the maximum correlation value causes performance degradation of frame synchronization.

8 illustrates a case where the size of the FFT is determined to be twice the size of the preamble.

(A) is the case of τ = 0 and (b) is the case of τ ≠ 0, when the FFT is determined to be 2N, which is twice the size of the preamble, in all cases, the entire interval of the differential received signal is always the FFT interval. Since contained within, no reduction in the maximum correlation value occurs.

In other words, if the FFT size is set to twice the preamble size, the performance deterioration factor can be eliminated.

9 is a diagram illustrating a calculation according to time of a receiving apparatus using a wireless communication system based FFT according to the present invention and a receiving apparatus according to the related art. As shown in the figure, the prior art has an N size correlator buffer and performs correlation of samples per sample.

On the other hand, the present invention performs the correlation of blocks per block using an FFT of 2N size.

FIG. 10 is a graph illustrating a comparison of a complex-numbered operation according to a preamble size of a differential correlation unit in a reception apparatus using a FFT based on a wireless communication system according to the present invention, and FIG. 11 is a wireless communication system based FFT according to the present invention. It is a graph showing a comparison between the real number operation according to the preamble size of the amplitude correlation unit in the receiving apparatus using the prior art.

As shown in the figure, comparing the computational complexity with respect to the preamble size N compares the prior art with the prior art of the differential correlator, and compares the prior art with the present invention of the amplitude correlator, according to the present invention. It can be seen that the calculation and complexity of the differential correlation unit and the amplitude correlation unit are lower.

Here, the simulation for verifying the performance of the frame synchronization structure according to the present invention was performed by repeating the AWGN (Additive White Gaussian Noise), which is arbitrarily changed, and recording statistical performance figures.

12 is a graph illustrating an error recognition rate according to a reception apparatus using a FFT based on a wireless communication system according to the present invention in comparison with the related art. As shown in the figure, an error recognition rate (False Acquisition) is compared according to Eb / No.

Here, the frequency error is a value obtained by normalizing the actual frequency error to the inverse of one sample interval, and the frequency error is randomly determined in the range of -0.1 to 0.1.

In addition, in the case of D = 15, it has a performance of about 3 * 10-3 at Eb / No of 2dB, and excellent performance in both D = 1, 15.

Therefore, it can be seen that the frame synchronizer proposed in the present invention has the same performance as the prior art and has a reduced complexity.

Although the preferred embodiments of the present invention have been described above by way of example, the scope of the present invention is not limited to such specific embodiments, and those skilled in the art are appropriate within the scope described in the claims of the present invention. It will be possible to change.

As described above, according to the present invention having the configuration described above, the frame synchronizer can improve performance by reducing the frame synchronization complexity of the receiver in a wireless communication system in which frequency error exists. Easy to use, FFT and IFFT can reduce the complexity of the algorithm and increase the processing speed.

Claims (15)

An RF processor for down-converting a frequency band by receiving a frame transmitted from the wireless communication system based transmitter in an RF band; An A / D converter converting the received frame into digital; A differential correlation unit for converting a time domain differential correlation operation between a reference signal of the frame converted by the A / D converter and a received signal to which a time error is applied to a multiplication operation of a frequency domain using an FFT module; An amplitude correlation unit for performing amplitude correlation between the reference signal of the frame converted by the A / D converter and the received signal using a moving sum to reduce the amount of calculation; A summing unit for summing a difference between an output of the differential correlation unit and an output of an amplitude correlation unit; A maximum value detector for estimating the time error; Receiver using a wireless communication system based FFT comprising a. The method according to claim 1, And the FFT module of the differential correlation unit converts the reference signal and the received signal into a frequency domain through a discrete Fourier transform. The method according to claim 2, And a differential correlation operation between the reference signal and the received signal converted into the frequency domain is changed into a multiplication operation of the frequency domain. The method according to claim 3, The reference signal and the received signal of the frequency domain, which are differentially correlated by the product of the frequency domain, are converted into the reference signal and the received signal of the time domain by a discrete Fourier inverse transform of the inverse FFT module. Receiving device using. The method according to claim 1, The differential correlation unit A first delayer delaying the received signal for a predetermined time; A conjugate complexer which conjugate-complexes the received signal of the first delayer; A first multiplier outputting a differential signal between the received signal and a reference signal through a complex product of the output of the A / D converter and the output of the conjugate complexer; An FFT module for converting the differential signal into a frequency domain with discrete Fourier transform for differential correlation operation; A frequency domain multiplier for multiplying the differential signal in a frequency domain by the FFT module; An inverse FFT module for performing a discrete Fourier inverse transform on the differential correlation operation computed by the frequency domain multiplier to transform into a time domain; A first absolute value operator for absolute value processing the result output by the inverse FFT module; Receiving device using a wireless communication system based FFT, comprising a. The method according to claim 5, And a correlation output value for the preamble samples of the plurality of frames is calculated by frequency domain computation of the FFT module, the frequency domain multiplier, and the inverse FFT module. The method according to claim 5, And a size of the FFT module and the inverse FFT module is twice the size of the preamble of the frame. The method according to claim 5, The differential correlator is a reception apparatus using a wireless communication system based FFT, characterized in that the complex multiplication amount is reduced by the FFT module, frequency domain multiplier, inverse FFT module. The method according to claim 1, The amplitude correlation unit A second delayer for delaying the output of the A / D converter for a predetermined time; A second absolute value calculator for absolute value processing the output of the A / D converter; A third absolute value calculator for absolute value processing the output of the second delayer; A second multiplier for multiplying outputs of the second absolute value calculator and the third absolute value calculator; A move adder for calculating the output of the second multiplier by a move adder; Receiving device using a wireless communication system based FFT, comprising a. The method according to claim 9, The amplitude correlator is a reception apparatus using a wireless communication system based FFT, characterized in that the amount of the real product is reduced by the mobile summation method of the mobile adder. The method according to claim 8 or 10, And a frame synchronization operation amount is reduced by a complex product operation of the differential correlation unit and a real product operation of an amplitude correlation unit. A first step of receiving a frame transmitted in an RF band by a wireless communication system based transmitter, down converting a frequency of a signal by an RF processor, and converting the frequency of the signal into a digital signal by an A / D converter; A second step of calculating, by the differential correlator, a differential correlation operation of a time domain between a reference signal and a received signal to which a time error is applied as a product of a frequency domain using an FFT module; A third step of moving and adding the reference signal and the received signal of the frame converted by the A / D converter so that the amount of calculation is reduced in an amplitude correlation unit; A fourth step of estimating a time error for frame synchronization in the maximum value detector by summing a difference between an output of the differential correlator and an output of an amplitude correlator; Receiving method using a wireless communication system based FFT comprising a. The method according to claim 12, In the step 2, the FFT module of the differential correlation unit converts a reference signal and a received signal into Fourier transforms and converts the received signals into a frequency domain. The method according to claim 13, And a differential correlation operation between the reference signal and the received signal converted into the frequency domain is changed into a multiplication operation of the frequency domain. The method according to claim 14, The reference signal and the received signal of the frequency domain, which are differentially correlated by the product of the frequency domain, are converted into the reference signal and the received signal of the time domain by a discrete Fourier inverse transform of the inverse FFT module. Receiving method using.

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