KR101080968B1 - Digital Broadcasting Terminal and Method for Detection Frame-Synchronization using Guard Interval thereof - Google Patents
Digital Broadcasting Terminal and Method for Detection Frame-Synchronization using Guard Interval thereof Download PDFInfo
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- KR101080968B1 KR101080968B1 KR1020050112949A KR20050112949A KR101080968B1 KR 101080968 B1 KR101080968 B1 KR 101080968B1 KR 1020050112949 A KR1020050112949 A KR 1020050112949A KR 20050112949 A KR20050112949 A KR 20050112949A KR 101080968 B1 KR101080968 B1 KR 101080968B1
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- frequency offset
- frame synchronization
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Abstract
The present invention provides a symbol delay unit for outputting a second received signal which has delayed a first received signal for a predetermined period of time; A multiplier for multiplying the first and second received signals; A time offset determiner configured to calculate a correlation value between the multiplied first and second received signals, and determine a point at which the maximum value of the calculated correlation value is detected as a time offset value; A frequency offset determiner for averaging the resultant signal multiplied by the first and second received signals, and determining a signal-to-noise ratio value of the averaged resultant signal as a frequency offset value; Frame synchronization detection using the protection interval of the digital broadcasting terminal and the digital broadcasting terminal comprising a frame synchronization performing unit performing frame synchronization using the time offset value and the frequency offset value determined by the time offset determination unit and the frequency offset determination unit. The present invention relates to a method for performing frame synchronization using a guard interval, thereby enabling frame synchronization without increasing power, thereby improving reception quality of a digital broadcast signal.
Cyclic Prefix, Guard Interval, Frame Synchronization
Description
1 shows a structure of a conventional digital broadcast signal transmission frame.
2 is a diagram illustrating a synchronization detection method using a conventional null symbol.
3 is a block diagram of an embodiment of a digital broadcasting terminal performing frame synchronization using a guard interval in an OFDM transmission system according to the present invention.
4 is a block diagram illustrating an embodiment of a time offset determiner according to the present invention.
5 is a block diagram illustrating an embodiment of a frequency offset determiner according to the present invention.
6 is a flowchart illustrating a frame synchronization detection method using a protection interval of a digital broadcasting terminal according to the present invention.
DESCRIPTION OF THE RELATED ART [0002]
310: symbol delay unit 320: multiplication unit
330: time offset determiner 340: frequency offset determiner
350: frame synchronization execution unit
The present invention relates to an Orthogonal Frequency Division Multiplexing (OFDM) system, and more particularly, to a digital broadcasting terminal and a digital broadcasting terminal for detecting synchronization using a guard interval at a receiving end of an OFDM system. A frame synchronization detection method using a guard interval.
At present, terrestrial digital broadcasting systems use OFDM.
Since the OFDM method transmits a digital broadcast signal to a plurality of sub-carriers, intersymbol interference (ISI) and intercarrier interference (ICI) are generated and transmitted. It can cause loss.
Therefore, in the case of a digital broadcasting terminal as a receiving end, it is important to find the exact starting position of a symbol in order to reduce the error due to the interference.
In order to find the exact starting position of the symbol, a frame synchronization detection method using a current null symbol is frequently used.
1 shows a structure of a conventional digital broadcast signal transmission frame.
2 is a diagram illustrating a synchronization detection method using a conventional null symbol.
Referring to FIGS. 1 and 2, a transmission channel has a synchronization channel at the beginning, and a Null (signal of all zeros) is placed at the beginning of the transmission frame to use power information measured at the receiver. Time synchronization.
That is, since the null symbol has no signal, the signal power is significantly smaller. Therefore, the receiving end adjusts time synchronization using the power information.
However, the synchronization detection method using the null symbol has difficulty in detecting accurate synchronization when noise or fading occurs in an actual channel environment. Even if the transmitter does not transmit a signal, a signal due to interference may appear in the channel. In this case, the power level of the null symbol portion detected at the receiving end is increased, thereby increasing the probability of failing to detect the correct start position of the frame.
The present invention is to solve the above problems, digital broadcasting terminal and digital to obtain a time offset value and a frequency offset value using a guard interval, and performs frame synchronization using the time offset value and the frequency offset value It is an object of the present invention to provide a frame synchronization detection method using a guard interval of a broadcast terminal.
According to an aspect of the present invention, there is provided a digital broadcasting terminal comprising: a symbol delay unit configured to output a second received signal having a delayed first received signal for a predetermined period; A multiplier for multiplying the first and second received signals; A time offset determiner configured to calculate a correlation value between the multiplied first and second received signals, and determine a point at which the maximum value of the calculated correlation value is detected as a time offset value; A frequency offset determiner for averaging the resultant signal multiplied by the first and second received signals, and determining a signal-to-noise ratio value of the averaged resultant signal as a frequency offset value; And a frame synchronization performer which performs frame synchronization using the time offset value and the frequency offset value determined by the time offset determiner and the frequency offset determiner.
According to another aspect of the present invention, there is provided a frame synchronization detection method using a protection interval of a digital broadcasting terminal, comprising: multiplying a first received signal and a second received signal delayed by the first received signal for a predetermined period; Calculating a correlation value between the multiplied first and second received signals; Determining a point at which the maximum value of the calculated correlation value is detected as a time offset value; Averaging the resultant signal obtained by multiplying the first and second received signals; Determining a signal-to-noise ratio value of the averaged resultant signal as a frequency offset value; And performing frame synchronization using the determined time offset value and frequency offset value.
The above-mentioned objects, features and advantages will become more apparent from the following detailed description in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Before describing the present invention, a brief description will be given of the guard interval used in the present invention.
The guard interval means an interval in which a signal after each symbol is copied to the front of the corresponding symbol by extending the symbol period to reduce the intersymbol interference caused by the multipath channel in the OFDM transmission channel.
3 is a block diagram of an embodiment of a digital broadcasting terminal performing frame synchronization using a guard interval in an OFDM transmission system according to the present invention.
Referring to FIG. 3, the
In the following description of the present invention, the OFDM signal before the delay is referred to as a first received signal, and the signal delayed by the
The
The time offset determiner 330 calculates a correlation value between the multiplied first and second received signals, and determines a time offset value at which the maximum value of the calculated correlation value is detected.
Hereinafter, an operation process of the
4 is a block diagram illustrating an embodiment of a time offset determiner according to the present invention.
Referring to FIG. 4, the
The
The
The time offset obtainer 333 determines the point where the maximum value of the correlation value output from the
The frequency offset determiner 340 averages the result signal obtained by multiplying the first received signal and the second received signal, performs an arc tangent process on the signal-to-noise ratio value of the average processed result signal, and performs the arc tangent process. The signal-to-noise ratio value is determined as the frequency offset value.
Hereinafter, an operation process of the
5 is a block diagram illustrating an embodiment of a frequency offset determiner according to the present invention.
Referring to FIG. 5, the
The
That is, since the first received signal is an original OFDM signal, and the second received signal is a delayed signal of the first received signal, a
(Desired Sygnal × Phase) 2 + 2 (Desired Sygnal × Noise) + (Noise) 2
When the three items of signals are input to the
The signal-to-
The arc
The arc tangent
The frequency offset obtainer 344 obtains a phase offset value using a signal-to-noise ratio value input from the
The frame
6 is a flowchart illustrating a frame synchronization detection method using a protection interval of a digital broadcasting terminal according to the present invention.
Referring to FIG. 6, the
In the following description of the present invention, the OFDM signal before the delay is referred to as a first received signal, and the signal delayed by the
The
The
The
The time offset
The
That is, since the first received signal is an original OFDM signal, and the second received signal is a delayed signal of the first received signal, a
(Desired Sygnal × Phase) 2 + 2 (Desired Sygnal × Noise) + (Noise) 2
When the three items of signals are input to the
The signal-to-
The
The
The frequency offset
The frame
The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.
In the frame synchronization detection method using the protection interval of the digital broadcasting terminal and the digital broadcasting terminal according to the present invention, as the frame synchronization is performed using the protection interval, it is possible to perform frame synchronization without increasing the power, and thus digital There is an effect of improving the reception quality of the broadcast signal.
Claims (14)
Priority Applications (1)
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KR1020050112949A KR101080968B1 (en) | 2005-11-24 | 2005-11-24 | Digital Broadcasting Terminal and Method for Detection Frame-Synchronization using Guard Interval thereof |
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KR1020050112949A KR101080968B1 (en) | 2005-11-24 | 2005-11-24 | Digital Broadcasting Terminal and Method for Detection Frame-Synchronization using Guard Interval thereof |
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KR20070054876A KR20070054876A (en) | 2007-05-30 |
KR101080968B1 true KR101080968B1 (en) | 2011-11-08 |
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