KR100443051B1 - A method for detecting initial signal of Multi carrier receive system and apparatus for performing said method - Google Patents

Abstract

The present invention relates to a method for detecting an initial signal of a multi-carrier reception system and an apparatus for performing the same. The present invention relates to a method for detecting a signal by obtaining a magnitude, autocorrelation, and cross-correlation of a received signal in a time domain. It performs automatic gain control by comparing the magnitude with the reference value and performs symbol synchronization by finding the point where autocorrelation value of symbol period is the minimum value.It detects and automatically detects multi-carrier received signal in shared communication media such as power line. Gain control and symbol synchronization can be performed.

Description

A method for detecting initial signal of Multi carrier receive system and apparatus for performing said method}

The present invention relates to a method for detecting an initial signal of a multi-carrier reception system and an apparatus for performing the same. More particularly, the present invention provides a method for quickly detecting an initial signal when a multi-carrier signal is received through a shared communication medium such as a power line. An initial signal detection method of a multi-carrier reception system capable of processing and an apparatus for performing the same.

In general, a discrete multi-tone (hereinafter, abbreviated as "DMT") system, which is a kind of a multi-carrier system, transmits information by using a plurality of carriers, and sampling at a receiving end. Demodulate the digital signal obtained by using a Fast Fourier Transform (" FFT ").

In such a DMT system, an encoder for encoding input data is usually provided to a transmitting end, an Inverse Fast Fourier Transform ("IFFT") for inverse Fourier transforming a signal encoded by the encoder, and an inverse Cyclic prefix inserter inserts every symbol by setting the length of Cyclic Prefix in the signal converted by Fourier converter, and DAC (Digital to Analog Converter) converts and outputs the signal output from this cyclic prefix inserter And a transmitter for transmitting a signal output from the DAC through a signal line.

In addition, the DMT system includes a receiver for receiving a signal, which is usually transmitted through a signal line, an ADC (Analog to Digital Converter) for A / D converting and outputting a signal received through the receiver, Cyclic Prefix remover for removing Cyclic Prefix from the signal output from ADC, Fourier transformer for Fourier transforming and outputting signal output from this Cyclic Prefix remover, Decoder for decoding the signal output from this Fourier transformer Is provided.

In order to correctly demodulate the signal at the receiving end, a signal detection (Physical Carrier Sense) (hereinafter, abbreviated as "PCS") that detects a received signal before demodulation and an automatic size of the received signal to an appropriate size are used. Automatic Gain Control (hereinafter abbreviated as "AGC") and Symbol Synchronization for Fourier Transform (FFT) must be processed.

Such PCS, AGC, and symbol synchronization may be performed in the time domain before the Fourier transform (FFT) or in the frequency domain after the Fourier transform (FFT).

For example, Asymmetric Digital Subscriber Lines (hereinafter, abbreviated as "ADSL") that communicate using a telephone line in a system using DMT for modulation and demodulation method, a receiver must first perform a PCS for detecting a received signal. In general, tone detection is used to detect specific frequencies in the frequency domain.

If the tone detection is successful, the AGC is performed later, which can be performed in either the time domain or the frequency domain. However, in order to implement an efficient algorithm, a method of calculating the magnitude of the signal in the time domain is commonly used.

After performing AGC, symbol synchronization is performed to find a boundary of a DMT symbol for demodulation of a signal by a Fourier transform (FFT), which may be performed in either the time domain or the frequency domain.

In this case, the time domain algorithm is simple in implementation and weak in narrowband noise, and the frequency domain algorithm is complicated in implementation and in strong in narrowband noise. ADSL uses a lot of frequency domain algorithms.

In ADSL, the most important reason for performing tone detection or symbol synchronization in the frequency domain is that the nature of the ADSL system using a telephone line enables communication between two modems in a point-to-point communication method. Once symbol setup is performed by link synchronization, data transmission can be continued without this process, so that a relatively large amount of time can be allocated to the first link setup, and a digital signal processor ("DSP") can be used. This is because you have time to perform complex calculations using ").

On the other hand, in a shared communication medium such as a power line, since multiple modems use the same medium, PCS, AGC, and symbol synchronization must be performed every time a modem for transmitting and receiving data is changed.

However, when this time is longer, the time to transmit data is relatively short, so that efficient communication cannot be performed. Therefore, PCS, AGC, and symbol synchronization must be performed within a short time.

Therefore

The present invention has been made in view of the above-described aspects, and when the multi-carrier signal of a high speed is received through a shared communication medium such as a power line, signal detection, automatic gain control, and symbol synchronization are quickly performed by time domain processing. An object of the present invention is to provide a method for detecting an initial signal of a multi-carrier reception system and an apparatus for performing the same.

1 is a schematic block diagram of a hardware device for performing an initial signal detection method of a multi-carrier reception system according to the present invention;

FIG. 2 is a block diagram illustrating a reception signal size calculator of FIG. 1; FIG.

3 is a block diagram illustrating the reception signal autocorrelation calculation unit shown in FIG. 1;

4 is a block diagram of an AGC controller shown in FIG. 1;

FIG. 5 is a block diagram illustrating a symbol synchronization detector shown in FIG. 1;

6 is a block diagram showing a preamble signal in a received signal for signal detection, automatic gain control, and symbol synchronization according to the present invention;

7 is a flowchart for explaining an initial signal detection method of a multi-carrier reception system according to an embodiment of the present invention;

8 to 14 are signal waveform diagrams for explaining an operation example of the initial signal detection apparatus of the multi-carrier reception system shown in FIG.

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

100: signal detection unit 110: reception signal size calculation unit

120: received signal size comparison unit 130: received signal autocorrelation calculation unit

140: received signal autocorrelation comparison unit 144: received signal cross-correlation value calculation unit

148: received signal cross-correlation comparison unit 150: logical product

160: signal detection signal control unit 200: automatic gain control unit

210: automatic gain controller 220: automatic gain control initial value setter

230: received signal size comparator 240: automatic gain control signal size table memory

250: automatic gain control signal converter 300: symbol synchronization detection unit

310: divider 320: autocorrelation negative reference value comparator

330: peak detector 340: symbol sync time converter

In order to achieve the above object, an initial signal detection method of a multi-carrier reception system according to a preferred embodiment of the present invention obtains a correlation value between a magnitude of a received signal and a time domain and compares the result with each set reference value and according to the comparison result. A signal sensing step for determining whether a signal is detected or not, and when a signal is received in the signal sensing step, comparing the symbol power size with a set reference value at one symbol period of the received signal and adjusting the received signal to a set level according to the comparison result. The automatic gain control step of outputting the automatic gain control signal for the automatic gain control step, and the automatic gain control signal outputted from the automatic gain control step, finds a point in time at which the correlation value of the symbol period is the minimum value, and determines the symbol synchronization and obtains a synchronization signal according to the determined symbol synchronization. Characterized in that it comprises a symbol synchronous detection step to output.

An apparatus for performing an initial signal detection method of a multi-carrier reception system according to a preferred embodiment of the present invention for achieving the above object, obtains the correlation value of the magnitude and time domain of the received signal, and compares it with the respective set reference value The signal detection unit determines whether or not to detect a signal according to the comparison result and outputs a signal detection signal, and when the signal is detected by the signal detection unit, compares the symbol power size with a set reference value at one symbol period of the received signal and compares the result with the reference value. The automatic gain control unit outputs an automatic gain control signal for adjusting the received signal to a set level according to the present invention. When the automatic gain control signal is output from the automatic gain control unit, the symbol synchronization is determined according to the point in time at which the correlation period of the symbol period is the minimum value. And a symbol synchronization detector for outputting a synchronization signal according to the determined symbol synchronization. The.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic block diagram of a hardware device for performing an initial signal detection method of a multi-carrier reception system according to the present invention. As can be seen with reference to the accompanying drawings, a hardware device for performing the present invention includes: Signal detection unit that calculates signal magnitude, autocorrelation value and mutual correlation value and compares them with each set reference value and determines whether to detect the signal according to the comparison result and outputs the signal detection signal (hereinafter, When the signal detection signal is output from the PCS unit 100, the symbol power magnitude is compared with the set reference value at one symbol period of the received signal, and the received signal is converted according to the comparison result. When the automatic gain control signal 200 outputs an automatic gain control signal for adjusting to a set level (hereinafter abbreviated as "AGC control part") and the automatic gain control signal is output from the AGC control part 200, Period of the auto-correlation value is determined according to the minimum of the symbol synchronization timing by the symbol synchronization comprises a detecting section 300 for outputting a synchronous signal based on the determined symbol synchronization.

According to an embodiment of the present invention, the PCS unit 100, as shown in Figure 1, the received signal size calculation unit 110 for calculating the size of the received signal, and the received signal size calculation unit 110 A received signal magnitude comparison unit 120 for comparing the magnitude of the received signal calculated by the reference value with a set reference value, a received signal autocorrelation value calculation unit 130 for calculating the autocorrelation value of the received signal, and the received signal autocorrelation A received signal autocorrelation value comparator 140 for comparing the autocorrelation value of the received signal calculated by the value calculator 130 with a set reference value, and a received signal cross-correlation value calculator 144 for calculating the cross-correlation value of the received signal. And a received signal cross-correlation comparison unit 148 for comparing the cross-correlation value of the received signal calculated by the received signal cross-correlation calculation unit 144 with a set reference value.

In addition, the PCS unit 100 performs an AND gate 150 for logically multiplying a value output from the received signal magnitude comparison unit 120 and a value output from the received signal autocorrelation comparison unit 140. And a signal output from the logical product 150, a value output from the cross-correlation comparison unit 148, and a control signal (Virtual Carrier Sense; hereinafter referred to as a "VCS signal") input from a separate upper controller. Accordingly, a signal detection signal controller (hereinafter referred to as "PCS signal controller") 160 for outputting a signal detection signal (hereinafter referred to as "PCS signal") may be configured.

Here, the PCS signal controller 160 sets the number of times (for example, 5 to 5) through the logical multiplication unit 150 within a predetermined time set after the time when the autocorrelation comparison unit 140 determines that a high autocorrelation signal is input. PCS signal is outputted only when a signal is inputted by about 10 times), and the output of the PCS signal is stopped by the VCS signal inputted from the host controller.

In addition, according to an embodiment of the present invention, the received signal magnitude calculating unit 110, as shown in Figure 2, the squarer 111 for squaring the received signal and the value output from the squarer A symbol delay unit 112 for delaying one symbol, a subtractor 113 for subtracting a value output from the symbol delay unit 112 with a symbol delay, and a subtractor 113 for subtracting the value output from the squarer 111; The accumulator 114 may accumulate and output an output value.

In addition, according to an embodiment of the present invention, the received signal autocorrelation calculation unit 130, as shown in Figure 3, the symbol delay unit 131 for delaying the received signal by one symbol, and the received signal And a multiplier 132 for multiplying a received signal delayed by one symbol through a symbol delayer 131, a symbol delayer 133 for delaying a value output from the multiplier 132 by one symbol, and a multiplier 132. A subtractor 134 subtracts the output value and the value output from the symbol delay unit 133, and an accumulator 135 accumulates the value output from the subtractor 134.

In addition, since the cross-correlation calculation unit 144 may be implemented using a general finite impulse response (FIR) filter, a separate description thereof will be omitted. For reference, however, when the cross-correlation calculation unit 144 is implemented as a general type FIR filter, it becomes an FIR filter having a tap number of one symbol length, so that it is difficult to actually implement it as the hardware size becomes too large. In this case, it is preferable to use a simple method such as obtaining a cross-correlation value using only the sign of the received signal.

In addition, according to an embodiment of the present invention, the AGC control unit 200, as shown in Figure 4, the automatic gain controller 210, automatic gain control initial value setter 220 and the received signal size comparator ( 230, the automatic gain control signal size table memory 240, and the automatic gain control signal converter 250.

The automatic gain controller (hereinafter referred to as "AGC controller") 210 instructs the comparison of the magnitude of the received signal when the PCS signal is input from the PCS unit 100, and the automatic gain control signal (hereinafter referred to as "AGC control signal"). And a control signal instructing to output an AGC signal having a value given by a VCS signal input from a separate upper controller (not shown).

Herein, the automatic gain controller 210 instructs to compare the magnitude of the received signal by a set number of times (for example, 2 to 3 times) for each symbol period to increase the accuracy of the AGC, and to control the output of the automatic gain control signal. It is desirable to output a signal.

The automatic gain control initial value setter 220 automatically controls the AGC initial value of a value given by a VCS signal input from a separate upper controller (not shown) according to a control signal applied from the AGC controller 210. To the signal converter 250.

The received signal size comparator 230 stores the magnitude value of the received signal input from the received signal size calculator 110 of the PCS unit 100 according to a control signal applied from the AGC controller 210. The AGC value, which is set in advance, is applied to the automatic gain control signal converter 250 according to the comparison result compared with the setting reference value stored in the 240.

Here, the setting reference value stored in the table memory 240 can be changed as necessary, thereby increasing flexibility.

The automatic gain control signal converter (hereinafter referred to as an "AGC signal converter") 250 is an AGC initial value or received signal applied from the AGC initial value setter 220 according to a control signal applied from the AGC controller 210. An automatic gain control signal (hereinafter referred to as an "AGC control signal") for adjusting the level of the received signal corresponding to the AGC value applied from the magnitude comparator 230 is output.

In addition, according to an embodiment of the present invention, the symbol synchronization detector 300, as shown in Figure 5, the divider 310, the negative reference value comparator 320 and the peak detector 330 And a symbol sync time converter 340.

The divider 310 obtains the received signal obtained from the received signal magnitude calculating unit 110 of the PCS unit 100 from the autocorrelation value of the received signal obtained from the received signal autocorrelation calculating unit 130 of the PCS unit 100. The reference value comparator 320 of the autocorrelation negative value is output by dividing the value output from the divider 310 according to the PCS signal applied from the PCS unit 100. Compare with the reference value of) and output the comparison result value according to the comparison result.

The peak detector 330 detects a negative peak level from a value output from the divider 310 according to the comparison result value output from the autocorrelation negative reference value comparator 320 and corresponds to the peak value. Outputs a detection signal.

Here, the peak detector 330 detects a negative peak value for a predetermined search period (for example, about 1/2 symbol period).

The symbol synchronization timing converter 340 outputs a synchronization signal for converting the symbol synchronization timing based on the timing at which the peak value detection signal is output from the peak detector 330.

FIG. 6 is a block diagram showing a preamble signal among received signals for signal detection, automatic gain control, and symbol synchronization according to the present invention. FIG. There is a preamble as shown. Here, "N-TRAIN" is a signal in which "TRAIN" is phase-inverted by 180 degrees. In the time domain, "N-TRAIN" is a signal obtained by multiplying "TRAIN" by "-1".

7 is a flowchart illustrating a method for detecting an initial signal of a multi-carrier reception system according to an exemplary embodiment of the present invention. Steps S2 to S40 show the PCS process, and steps S50 to S40. The AGC process is shown up to (S75), and the symbol synchronization process is shown from step S80 to step S110. The method for detecting an initial signal of the multi-carrier reception system according to the present invention is described with reference to FIGS. This will be described with reference to the hardware device.

First, the PCS according to the present invention uses a correlation between the magnitude and autocorrelation of the received signal in the time domain in the preamble section of the received signal in which the same data is transmitted in units of DMT symbols. That is, when the cross-correlation value is greater than or equal to the predetermined reference value, if the signal size is greater than or equal to the predetermined reference value and the autocorrelation value is greater than or equal to the predetermined reference value, the signal is received. However, the signal magnitude and autocorrelation value are calculated based on one symbol period, and when the signal magnitude and autocorrelation value continuously exceed each set reference value by a set number n, it is detected that a signal is received. For example, the setting frequency n is preferably about 5 to 10 times.

In more detail, when a signal is received, the PCS unit 100 calculates the cross-correlation value of the received signal, the auto-correlation value, and the magnitude of the received signal, and compares the obtained cross-correlation value with the set reference value ref0. It is determined whether the cross-correlation value of the received signal is larger than the set reference value ref0 (S2).

As a result of the determination in step S2, if the correlation value of the received signal is larger than the set reference value ref0, the PCS unit 100 resets the built-in timer (not shown) to count the time (S4). In step S6, it is determined whether the checked current time has passed the set time by checking the counted time. At this time, if the checked current time has passed the set time, it is assumed that no signal is received and the flow returns to the step S2.

If the current time checked as the result of the determination in step S60 does not pass the setting time, the magnitude of the received signal obtained in advance by the PCS unit 100 is compared with a predetermined setting reference value ref1. It is determined whether the magnitude of the received signal is larger than the set reference value ref1 (S10), and the magnitude of the received signal is compared with the predetermined set reference value ref2 by comparing the previously obtained autocorrelation value with the set reference value ref2. It is determined whether it is larger than S20.

Here, the equation for calculating the magnitude of the received signal is as shown in Equation 1 below. In order to implement Equation 1 as hardware, the complexity of the hardware increases, so that Equation 1 is derived from Equation 1 below. Using Equation 2, the size of the received signal can be calculated with a simpler hardware configuration.

For reference, the received signal magnitude calculator shown in FIG. 2 implements Equation 2 below in hardware.

In Equations 1 and 2, P _symbol is a symbol size of a received signal, S _k is a received signal, and N is a number of samples per symbol. .

The equation for calculating the autocorrelation value of the received signal is shown in Equation 3 below.

In Equation 3, C _symbol is an autocorrelation value of a received signal.

The correlation value used for the initial signal detection in the multi-carrier system may be used by selecting one of a) autocorrelation value between two consecutively received symbols and b) cross-correlation value between the received symbol and a preset value. The method of obtaining the correlation value between two consecutively received symbols is strong in channel distortion and white noise (AWGN), while it is weak in narrowband noise such as radio frequency interference (RFI), and the correlation between the received symbol and a predetermined value is obtained. Since the method is strong in narrowband noise but strong in channel distortion and white noise, it can be implemented by selecting any one of the above two methods of obtaining correlations according to the usage environment. However, in the present invention, there is a high possibility that signal detection is incorrect when each correlation value is used, and thus, a case in which both correlation values are obtained and used to solve each problem will be described as an example.

The PCS unit 100 compares the autocorrelation value and the magnitude of the received signal during the set time when the cross-correlation value is equal to or greater than the set reference value. If either of the magnitude of the received signal and the autocorrelation value is less than or equal to the set reference value in steps S10 and S20, the counter value is set to "0" (S25).

In the PCS unit 100, when the magnitude and autocorrelation of the received signal exceed the respective reference values ref1 and ref2 in the steps S10 and S20, the counter value checked by checking the current counter value is n−. It is determined whether it is 1 (S30), and if the current counter value is not n-1 as a result of determination, it increments "1" to the current counter value (S35). Here, "n" is a setting frequency.

In the step S30, when the checked counter value is n-1, since the magnitude of the received signal and the autocorrelation value exceed the respective reference values ref1 and ref2 at the same time by n times, the PCS unit 100 In operation S40, the PCS signal is determined to be detected by the AGC controller 200 and the symbol synchronization detector 300. However, if the condition of step S30 is not satisfied during the set time, it is determined that the autocorrelation value is incorrectly detected, and the PCS unit 100 returns to step S20 for comparing the autocorrelation value again. At this time, it goes without saying that step S35, step S6, and step S10 are performed.

The AGC according to the present invention is performed after the PCS signal is output, and compares the size of one symbol of the received signal with a value of a preset table, and determines the size of the received signal based on the comparison result and determines the received signal. Determine the AGC value according to the size of.

Here, the value of the table is determined in consideration of the distortion of the received signal power.

At this time, it is preferable to perform AGC repetitively as many times as the set number (m) in order to increase the accuracy, and when considering that the power of the symbol should be updated when the AGC value is changed and the wave of the received signal is generated It is desirable to delay the symbol of the signal by one symbol period and compare it with the values in the table.

The initial AGC value before the reception signal is received is a value given according to a control signal from a separate upper controller, and this initial value is preferably changed flexibly according to the channel situation.

In detail, the AGC controller 200 delays one symbol period with respect to the magnitude value of the received signal calculated by the PCS unit 100 when the PCS signal is input from the PCS unit 100. It compares with the reference value ref3 (S50).

The AGC control unit 200 initially outputs an AGC control signal of an initial value given according to a VCS signal input from a separate upper controller, and uses the comparison result in step S50 to compare the received signal with a suitable preset reception signal. Obtaining the difference with the magnitude and outputs an AGC control signal of a value that can be adjusted (S60).

The AGC controller 200 outputs an AGC control signal and then checks the current counter value to determine whether the checked current counter value is m-1 (S70), and if the current counter value is not m-1, as a result of the determination. After increasing " 1 " to the current counter value (S75), the process returns to step S50, and the above-described steps S50 to S70 are semi-permanently performed until the counter value reaches m-1.

That is, the accuracy of the AGC is increased by m times of setting times.

Next, the symbol synchronization according to the present invention is performed after the end of the AGC, and finds and synchronizes when the autocorrelation value of the symbol becomes a minimum by the preamble of the received signal as shown in FIG. Find out the time.

The autocorrelation value of the received signal gradually increases when the preamble signal is received, maintains a constant value at a positive value, and is negative when one "N-TRAIN" of the preamble is received. It will have the minimum value of.

In order to find the minimum value of the negative (-), a certain search window must be determined. For this, if the autocorrelation value is smaller than the negative reference value, the minimum value of the negative value is started from this point. It continues for a period of time (e.g., about half a symbol period).

The position of the symbol synchronization can be known by the position of the negative minimum value in the search window.

In more detail, the symbol synchronization detector 300 checks whether the PCS signal is output from the PCS unit 100 (S80), and if the PCS signal is not output, symbol synchronization control is not performed. Sets the counter value to "0" to perform signal detection, that is, PCS.

If the PCS signal is output from the PCS unit 100 in the step S80, the symbol synchronization detector 300 sets the autocorrelation value of the received signal calculated and input by the PCS unit 100 in advance. Is compared with a reference value ref4 of step S90.

In this case, the autocorrelation value input to the symbol synchronization detector 300 is normalized by dividing the received signal size to compensate for the change in the received signal size according to the channel condition, and then negative (ref4). ) Is preferably compared to (see the configuration of the symbol synchronization detector of FIG. 5).

If the autocorrelation value of the received signal is smaller than the negative reference value ref4 at step S90, the symbol synchronization detector 300 performs the minimum value of the received signal autocorrelation value for a set time (for example, about 1/2 symbol period). In step S100, the symbol synchronization point is determined according to the point of time when the autocorrelation value of the received signal is minimum within the set time, and the synchronization signal for controlling symbol synchronization is output accordingly (S110).

For reference, FIG. 8 shows an example of a signal received by adding white noise (AWGN) and an actual transmission signal, and it is difficult to distinguish whether a signal is being received when looking at the same figure. However, the autocorrelation thereof shows that a signal is being received. FIG. 9 shows the signal of FIG. 8 as the ratio of the autocorrelation value and the received signal size.

Referring to FIG. 9, the autocorrelation value gradually increases after approximately 1300 samples and reaches a peak at approximately 1900 samples, thereby maintaining a substantially constant value. This indicates that a signal is being received at approximately 1300 sample points, with the value gradually decreasing after approximately 4900 samples, with the sign becoming negative at approximately 5100 samples and the minimum at approximately 5400 samples.

That is, it can be seen that the "N-TRAIN" signal of the preamble signal has been received at about 5400 sample points, and that data will be received thereafter.

FIG. 10 illustrates a received signal having a Signal to Noise Ratio (SNR) of about -3 dB, which is more difficult to distinguish between signals compared to the waveform of FIG. 8. have. This is shown in FIG. 11, which is expressed as a ratio of autocorrelation value and received signal size to the received signal of FIG. 10, to confirm whether a signal is received.

However, when comparing the waveform of FIG. 11 with the waveform of FIG. 9, it can be seen that the waveform of FIG. 11 is more disordered, and that the size of the vertices is also smaller overall.

In other words, it can be seen that if the reference value for the magnitude and autocorrelation of the received signal is fixed, PCS may be incorrectly set or symbol synchronization may not be found when a large noise is added to the received signal. In the PCS process and the symbol synchronization process, each reference value is appropriately changed to prevent the case where the PCS is incorrectly determined or the symbol synchronization is not found.

FIG. 12 shows waveforms in the time domain of the received signal to which the RFI noise is added. FIG. 13 shows waveforms in the frequency domain obtained by fast Fourier transforming the received signal of FIG. 12. FIG. 14 shows the waveforms in the received signal of FIG. The autocorrelation for this is the normalized value of the signal.

It can be seen that the negative vertex of the waveform of FIG. 14 is smaller than that of the waveforms of FIGS. 9 and 11, which may occur when symbol synchronization is not found according to the frequency and magnitude of the RFI noise. It represents. Accordingly, in the present invention, by appropriately changing the reference value in the symbol synchronization process according to the channel situation, it is possible to prevent the case that the symbol synchronization is not found for the received signal to which the RFI noise is added.

The present invention is described above by illustrating specific embodiments, but the present invention is not limited to the above embodiments. Those skilled in the art can easily make various changes and modifications to the present invention, and it should be noted that such variations or modifications are included within the scope of the present invention as long as the features of the present invention are used.

As described above, the present invention obtains the signal and the correlation value of the received signal in the time domain, and performs automatic gain control by comparing the magnitude of the received signal with the reference value in the time domain, and the autocorrelation value of the symbol period is the minimum value. It is configured to perform symbol synchronization by finding the point, and can quickly perform deep detection, automatic gain control, and symbol synchronization on a multicarrier received signal in a shared communication medium such as a power line.

In addition, the present invention can be strengthened in narrowband noise characteristics by appropriately changing the reference values used in signal detection and symbol synchronization.

Claims (19)

In the method for detecting an initial signal in a multi-carrier signal receiving system, A signal sensing step of obtaining a correlation value between the magnitude of the received signal and the time domain, comparing the result with each set reference value, and determining whether the signal is detected based on the comparison result; When the signal is detected in the signal detection step, the automatic gain control outputs an automatic gain control signal for adjusting the received signal to the set level according to the comparison result by comparing the symbol power size with a set reference value at one symbol period of the received signal. Step, When the automatic gain control signal is output in the automatic gain control step, the multi-carrier characterized in that it consists of a symbol synchronization detection step for determining the symbol synchronization to find the point of time when the correlation value of the symbol period is the minimum value and outputs a synchronization signal according to the determined symbol synchronization Initial signal detection method of receiving system. 2. The method of claim 1, wherein in the signal detection step, an autocorrelation value between two consecutively received symbols is obtained. The method of claim 1, wherein in the signal detection step, a correlation value between a predetermined value and a symbol of a received signal is obtained. The signal detection step according to claim 1, wherein in the signal detection step, reception of a signal is detected when the number of times that the cross-correlation value and the auto-correlation value of the time domain and the auto-correlation value simultaneously exceeds the set number n is greater than or equal to the set number (n). Initial signal detection method of a multi-carrier receiving system, characterized in that determined to. 2. The method of claim 1, wherein in the automatic gain control step, the set reference value is stored in a signal size table memory and can be arbitrarily varied. The method of claim 1, wherein the automatic gain control step is performed by a set number (m) every one symbol period. The method of claim 1, wherein in the automatic gain control step, an automatic gain control signal having an initial value given by a control signal applied from a separate upper level controller is initially output. . The method of claim 1, wherein in the symbol synchronization detection step, a process of normalizing by dividing a correlation value of a received signal by a magnitude of a received signal is further performed. The method of claim 1, wherein the symbol synchronization detecting step further includes a step of comparing a correlation value with a preset negative reference value, and finding a minimum value for a predetermined search period when the correlation value is less than the negative reference value. Initial signal detection method of a multi-carrier receiving system. An apparatus for performing an initial signal detection method for outputting a signal detection signal, an automatic gain control signal and a synchronization signal in a multi-carrier signal receiving system, A signal detection unit for obtaining a correlation value of a received signal and a time domain, comparing the result with each set reference value, determining whether the signal is detected according to the comparison result, and outputting a signal detection signal; An automatic gain control unit for outputting an automatic gain control signal for adjusting a received signal to a set level according to a result of the comparison by comparing a symbol power size with a set reference value when a signal is detected by the signal detector; , When the automatic gain control signal is output from the automatic gain control unit, a multi-carrier reception system comprising a symbol synchronization detector for outputting a synchronization signal according to the symbol synchronization determined by symbol synchronization according to the point of time that the correlation value of the symbol period is the minimum value Apparatus for performing the initial signal detection method of the. The method of claim 10, wherein the signal detection unit, A received signal size calculating unit calculating a magnitude of a received signal; A received signal size comparison unit which compares a magnitude of the received signal with a set reference value; A received signal correlation value calculating unit calculating a correlation value of the received signal; A received signal correlation value comparing unit for comparing the correlation value of the received signal with a set reference value; A logical multiplication unit for performing an AND operation on the value output from the received signal magnitude comparison unit and the value output from the received signal correlation comparison unit; And a signal detection signal control unit for outputting a signal detection signal according to the signal output from the logical multiplication unit. 12. The method of claim 11, wherein the signal detection signal controller further performs a control operation of outputting a signal detection signal according to a control signal input from a separate upper controller. Device for performing. The method of claim 11, wherein the received signal size calculation unit, A squarer that squares the received signal, A symbol delayer for delaying a value output from the squarer by one symbol; A subtractor for subtracting a value output from the squarer and a value delayed by one symbol from the symbol delayer; And an accumulator for accumulating and outputting a value output from the subtractor. The method of claim 11, wherein the received signal correlation calculation unit, A first symbol delayer for delaying the received signal by one symbol; A multiplier for multiplying a received signal by a symbol delayed received signal through the symbol delayer; A second symbol delayer for delaying a value output from the multiplier by one symbol; A subtractor for subtracting the value output from the multiplier and the value output from the second symbol delayer; And an accumulator for accumulating a value output from the subtractor. The method of claim 10, wherein the automatic gain control unit, An automatic gain controller for instructing a comparison of the magnitude of a received signal and outputting a control signal for instructing the output of the automatic gain control signal when the signal sensing signal is output from the signal sensing unit; A table memory in which a set signal size value is stored; A received signal size comparator for comparing the magnitude of the received signal with a set signal size value stored in the table memory according to a control signal applied from the automatic gain controller and outputting a preset auto gain control value according to the comparison result; And an automatic gain control signal converter converting the automatic gain control value output from the received signal magnitude comparator into an automatic gain control signal corresponding to the control signal applied from the automatic gain controller. An apparatus for performing an initial signal detection method of a carrier receiving system. The multi-carrier according to claim 15, wherein the automatic gain controller instructs a comparison of the magnitude of the received signal by a set number (m) every one symbol period and outputs a control signal instructing the output of the automatic gain control signal. Apparatus for performing the initial signal detection method of the receiving system. 17. The automatic gain control signal according to claim 10, 15, or 16, wherein the automatic gain control unit outputs an automatic gain control value of an initial value given according to a control signal input to the automatic gain controller from a separate host controller. And an automatic gain control initial value setter applied to a converter. 11. The apparatus of claim 10, wherein the symbol synchronization detector comprises: a divider for dividing a correlation value of a received signal obtained by the signal detector by a magnitude of a received signal obtained by the signal detector; A correlation value negative reference value comparator for outputting a comparison result value comparing the value output from the divider with a preset negative reference value according to the signal detection signal applied from the signal detection unit; A peak detector for detecting a negative peak value from a value output from the divider according to a comparison result value output from the negative reference value comparator and outputting a corresponding detection signal; Performing an initial signal detection method of a multi-carrier receiving system, characterized in that it comprises a symbol synchronization time converter for outputting a synchronization signal for converting a symbol synchronization time point on the basis of the time point when the peak value detection signal is output from the peak detector Device for. 19. The apparatus of claim 18, wherein the peak detector detects a negative peak value for a predetermined search period.