KR100744056B1 - Apparatus and method for transmitting and receiving digital broadcasting signal - Google Patents

Abstract

An apparatus for transmitting and receiving a digital broadcasting signal and a transmitting and receiving method therefor are provided to stably transmit and receive the digital broadcasting signal without the loss of the signal or the error operation of the transmitting and receiving apparatus by calculating a signal deviation of a transmission signal and correcting the calculated signal deviation to be accurately synchronized to a standard time. A standard time input unit(310) receives a standard time. A signal deviation calculating unit(320) calculates a signal deviation of a transmission signal with respect to the standard time. A TDS-OFDM(Time Domain Synchronous-Orthogonal Frequency Division Multiplexing) modulating unit(360) includes certain information in a TDS-OFDM symbol of a frequency domain, and performs the TDS-OFDM modulation of the TDS-OFDM symbol. A signal reconfiguring unit(370) reconfigures the TDS-OFDM modulated signal to be synchronized to the standard time by using the calculated result of the signal deviation calculating unit(320) and the information included in the TDS-OFDM symbol. The certain information is TDS-OFDM symbol length or time information adjusted on the basis of the signal deviation calculation.

Description

Apparatus and method for transmitting and receiving digital broadcasting signal

1 is a diagram illustrating a frame structure according to a DMB-T system.

2 is a diagram schematically illustrating a problem caused by initialization of a transmission signal according to a DMB-T system.

3 is a block diagram schematically showing an apparatus for transmitting a digital broadcast signal according to the present invention;

4 is a diagram illustrating a method of correcting a transmission signal according to an embodiment of the present invention.

5 is a flowchart illustrating a method of transmitting a digital broadcast signal according to the present invention.

* Description of the main parts of the drawings *

310: standard time input unit 320: signal deviation calculation unit

330: Adjusted TDS-OFDM symbol length or time information

340: data 350: MUX

360: TDS-OFDM modulation unit 370: signal reconstruction unit

The present invention relates to a transmission and reception apparatus for a digital broadcast signal, and more particularly, to calculate and correct a signal deviation of a transmission signal so as to be accurately synchronized to a standard time so that a stable transmission and reception without loss of a signal or malfunction of the transmission and reception apparatus is achieved. A transmission and reception apparatus for a digital broadcast signal and a transmission method are provided.

Digital broadcasting has the advantage of system integration and interoperability through digital coding system, unlike analog broadcasting. Therefore, it is equipped with conditions that can be the core of so-called media convergence using computers and networks, and it is becoming an opportunity to change the unilateral and downward analogue broadcasting area to a new phase by gradually adding interactive functions.

Current digital terrestrial broadcasting systems include the United States Advanced Television Systems Committee (ATSC) system using 8-VSB (Vestigial Side Band), European DVB-T system based on Coded Orthogonal Frequency Modulation (COFDM), and BST-OFDM (Bandwidth). Three standards of ISDB-T system in Japan based on Segmented Transmission-OFDM are proposed. Recently, various transmission methods such as Terrestrial Digital Multimedia Television Broadcasting (DMB-T), Advanced Digital Television Broadcast-Terrestrial (ADTB-T), BDB-T, CDTB-T, and Synchronized Multi-Carrier CDMA (SMCC) have been proposed. have.

Among them, DMB-T system has advantages for mobile reception and data broadcasting and uses TDS-OFDM (Time Domain Synchronous-Orthogonal Frequency Division Multiplexing) transmission method.

1 illustrates a frame structure according to the DMB-T system disclosed in International Publication No. WO 02/17615 A2. The frame structure has a hierarchical structure, and the basic frame is called a signal frame. Each signal frame consists of synchronization information (frame sync) and frame segments. Signal frames are gathered to form a frame group, and the first frame of the frame group becomes a frame group header. Frame groups are assembled to form a superframe, and 478 superframes form a superframe group, which is the highest layer. It can be seen that one superframe consists of 512 frame groups and one frame group consists of 255 signal frames.

The superframe group is repeated every day, resetting the frame structure to be synchronized to PST at AM 0: 0: 0 or a predetermined reference time, after which a new superframe group is started. This initialization also includes the initialization of the randomizer associated with the PN sequence generation.

In such a system, the last superframe of the superframe group may not complete at reset time. In this case, if a signal that has been continuously transmitted is suddenly stopped and a new signal synchronized with an external time is transmitted, a loss of the signal occurs and a device for transmitting and receiving the signal is unreasonable.

2 illustrates the problem of the initialization of the transmission signal according to the DMB-T system in detail in terms of the signal. FIG. 2 (a) shows that the existing transmission signal is slowly transmitted based on the time of the initialization time. This is a case where initialization is performed at a predetermined reference time before all are transmitted. In this case, the existing transmission signal is ignored by initialization of the transmission signal and a new signal is transmitted, thereby causing information loss of the existing transmission signal. Since this has occurred in the transmitter, there is no way for the receiver to recover it. Therefore, the signal quality may deteriorate or an error may occur in the entire transmission / reception system.

2B illustrates a case in which the existing transmission signal is quickly transmitted based on the time of the initialization time and ends before the initialization time, and the next signal is already transmitted. In this case, too, when the predetermined reference time is reached, the existing transmission signal is ignored and a new signal is transmitted by the initialization of the transmission signal, resulting in loss of information, thereby causing an error in the transmission signal and causing a malfunction of the transceiver.

The present invention has been made to solve the above problems, by transmitting and receiving a digital broadcast signal transmission and reception device to achieve stable transmission and reception without loss of signal or malfunction of the transmission and reception device by calculating and correcting the signal deviation of the transmission signal to be correctly synchronized in standard time and To provide a transmission and reception method.

In order to achieve the above object, a digital broadcast signal transmitting apparatus according to the present invention comprises a standard time input unit for receiving a standard time; A signal deviation calculator for calculating a signal deviation of the transmission signal with respect to the standard time; A TDS-OFDM modulator for performing TDS-OFDM modulation by including predetermined information in a TDS-OFDM symbol in a frequency domain; And a signal reconstruction unit configured to reconstruct the TDS-OFDM modulated signal to be synchronized in the standard time by using the calculation result of the signal deviation calculator and the information included in the TDS-OFDM symbol, wherein the predetermined information is the signal deviation. It is preferred that it is adjusted TDS-OFDM symbol length or time information based on the calculation.

In addition, the signal reconstruction unit preferably removes the signal deviation of the TDS-OFDM symbol from the TDS-OFDM symbol or inserts it into the TDS-OFDM symbol so as to correct the signal deviation of the transmission signal in units of TDS-OFDM symbols. Do.

In addition, the signal to be removed is preferably a trained training sequence, and the inserted signal is preferably a null signal.

In addition, the method for transmitting a digital broadcast signal according to the present invention comprises the steps of receiving a standard time; Calculating a signal deviation of the transmission signal with respect to the standard time; Performing TDS-OFDM modulation by including predetermined information in a TDS-OFDM symbol in a frequency domain; And reconstructing the TDS-OFDM modulated signal to be synchronized in the standard time by using the signal deviation calculation result and the information included in the TDS-OFDM symbol, wherein the predetermined information is based on the signal deviation calculation. It is preferably the adjusted TDS-OFDM symbol length or time information.

Hereinafter, the present invention will be described in detail with reference to the drawings.

3 is a block diagram schematically showing an apparatus for transmitting a digital broadcast signal according to the present invention. The standard time input unit 310 receives a standard time from the outside. The standard time may be a time arbitrarily set according to the user's intention in addition to the standard time. The standard time is the correct time for each country or region, such as Korea Standard Time, Pacific Standard Time (PST) or Beijing Standard Time.

The signal deviation calculator 320 calculates a signal deviation of the transmission signal with respect to the standard time. The signal transmitted with the time information must have an error with respect to the standard time, which is an accurate time, but the signal deviation indicates the bias due to the inconsistent synchronization of the transmission signal with respect to the standard time. Therefore, it is necessary to transmit the signals in time synchronization by reconstructing the transmission signal based on the calculated result of calculating the signal deviation. A method of reconstructing the transmission signal by calculating the signal deviation will be described with reference to FIG. 4.

The TDS-OFDM symbol length or time information 330 adjusted for each TDS-OFDM symbol may be added to the data 340 through the MUX 350 by referring to the calculation of the signal deviation calculator 320. The signal deviation of each TDS-OFDM symbol can be known with reference to this information, and used for reconstruction of a signal as shown in FIG. This continuously corrects the signal deviation of the transmission signal in units of TDS-OFDM symbols so that the existing transmission signal can be accurately synchronized at the time of initialization. The initialization is generated at a predetermined reference time so that a new transmission signal synchronized with the input standard time is transmitted. The predetermined reference time may be, for example, AM 0: 0: 0 o'clock in Korean standard time, and a new signal synchronized with the standard time is transmitted after the initialization.

The TDS-OFDM modulator 360 modulates data including the TDS-OFDM symbol length or time information 330 adjusted for every TDS-OFDM symbol in a TDS-OFDM manner.

The signal reconstruction unit 370 reconstructs the TDS-OFDM modulated signal based on the calculation result of the signal deviation calculator 320 and the adjusted TDS-OFDM symbol length or time information 330.

4 schematically illustrates a method of correcting a transmission signal according to an embodiment of the present invention in terms of signals.

As shown in FIG. 4, the signal deviation of the existing transmission signal with respect to the standard time input to the standard time input unit 310 is continuously corrected in units of TDS-OFDM. When the existing transmission signal is transmitted later than the standard time, some signals are removed from the TDS-OFDM symbol. When the existing transmission signal is transmitted earlier than the standard time, a null signal or a predetermined signal is inserted into the TDS-OFDM. . The signal to be removed may then be a promised training sequence that does not affect the recovery of the signal, and the inserted signal may be a null signal or a predetermined signal that also does not affect the recovery of the signal.

Therefore, at a predetermined reference time at which a signal deviation is continuously corrected and initialized in units of TDS-OFDM symbols while a signal is transmitted, a signal synchronized with standard time can be transmitted. The adjusted TDS-OFDM symbol length or time information is referred to to determine the amount of signal to be removed or inserted for each TDS-OFDM symbol.

5 is a flowchart illustrating a method of transmitting a digital broadcast signal according to the present invention. As shown in FIG. 5, the method for transmitting a digital broadcast signal according to the present invention first receives a standard time (S510). Next, the signal deviation of the transmission signal with respect to the standard time is calculated (S520). Next, the TDS-OFDM modulated signal includes predetermined information in the TDS-OFDM symbol in the frequency domain (S530), and the TDS-OFDM modulated signal is standardized by using the signal deviation calculation result and the information included in the TDS-OFDM symbol. It is reconfigured to be synchronized in time (S540). At this time, the predetermined information used is adjusted TDS-OFDM symbol length or time information based on the signal deviation calculation.

At this time, in step S540, the signal deviation of the TDS-OFDM symbol is removed from the TDS-OFDM symbol or inserted into the TDS-OFDM symbol so as to correct the signal deviation of the transmission signal in units of TDS-OFDM symbols. The magnitude of the signal deviation of the TDS-OFDM symbol is determined with reference to the adjusted TDS-OFDM symbol length or time information included in the TDS-OFDM symbol. Here, the signal to be removed is a promised training sequence, and the signals to be inserted are null signals or signals that do not affect the restoration of the signal as a predetermined signal.

The present invention provides a receiving apparatus capable of detecting and processing a removed or inserted signal by detecting a reconstructed signal as described above. 6 illustrates an apparatus for receiving a digital broadcast signal according to the present invention. The reconstruction signal determiner 610 receives the signal and determines whether it is a reconstructed signal to be synchronized in standard time. When the TDS-OFDM demodulator 620 is a reconstructed signal as determined by the reconstruction signal determiner 610, the TDS-OFDM demodulator 620 recognizes a signal removed from or inserted into the transmission signal and demodulates the TDS-OFDM. The TDS-OFDM demodulated signal is separated into data 640 and adjusted TDS-OFDM symbol length or time information 650 via DEMUX 630. The present invention also provides a method for receiving a digital broadcast signal corresponding to the apparatus for receiving such a digital broadcast signal.

According to the present invention, there is provided a digital broadcast signal transceiver and a transmission / reception method for stably transmitting and receiving a signal without loss of signal or malfunction of the transmission / reception apparatus by calculating and correcting a signal deviation of a transmission signal so as to be synchronized in standard time accurately.

Although the above has been illustrated and described with respect to preferred embodiments of the present invention, the present invention is not limited to the above-described specific embodiments, and those skilled in the art without departing from the gist of the present invention. Anyone can make various modifications, as well as such modifications or variations are within the scope of the appended claims.

Claims (5)

A standard time input unit for receiving standard time; A signal deviation calculator for calculating a signal deviation of the transmission signal with respect to the standard time; A TDS-OFDM modulator for performing TDS-OFDM modulation by including predetermined information in a TDS-OFDM symbol in a frequency domain; And And a signal reconstructing unit configured to reconstruct the TDS-OFDM modulated signal to be synchronized in the standard time by using the calculation result of the signal deviation calculator and information included in the TDS-OFDM symbol. And the predetermined information is adjusted TDS-OFDM symbol length or time information based on the signal deviation calculation. The method of claim 1, wherein the signal reconstruction unit removes the signal deviation of the TDS-OFDM symbol from the TDS-OFDM symbol or inserts the TDS-OFDM symbol into a TDS-OFDM symbol to correct the signal deviation of the transmission signal in units of TDS-OFDM symbols. Apparatus for transmitting digital broadcast signal. The apparatus of claim 2, wherein the signal to be removed is a promised training sequence. The apparatus of claim 2, wherein the inserted signal is a null signal. Receiving a standard time; Calculating a signal deviation of the transmission signal with respect to the standard time; Performing TDS-OFDM modulation by including predetermined information in a TDS-OFDM symbol in a frequency domain; And Reconstructing the TDS-OFDM modulated signal to be synchronized in the standard time by using the signal deviation calculation result and the information included in the TDS-OFDM symbol, And the predetermined information is adjusted TDS-OFDM symbol length or time information based on the signal deviation calculation.

Images