KR100997155B1 - OFDM transmitter capable of adjusting size of PN and inserting adjusted PN into OFDM symbol - Google Patents

Abstract

An OMD transmitter capable of adjusting and inserting pseudo noise string information into an OMD symbol is disclosed. The OMD transmitter comprises: an FEC coding unit which performs coding for correcting an error occurring in transmission on an OMD DM symbol, and an IDFT unit which performs inverse discrete Fourier transform on an OFM symbol which has been subjected to error correction coding A GI insertion portion for inserting a guard section for suppressing interference between the UF DM symbols to the UF DM symbol on which the inverse discrete Fourier transform is performed, and a size exceeding 255 symbols for the UF DM symbol into which the guard interval is inserted PN insertion part for inserting pseudo noise string information, pulse molding part for performing pulse shaping filtering on the OMD DM symbol in which pseudo noise string information is inserted, and RF for high frequency amplification of the OSF symbol with pulse shaping filtering performed It has an amplification part. The OMD receiver can more accurately perform the restoration of the OMD signal through synchronization with the received OMD signal and channel estimation.

UFDM, pseudo-noise train, size, adjustment, guard interval

Description

UFDM transmitter capable of adjusting the size of pseudonoise string information to be inserted into the UFDM symbol and a method of transmitting the UFDM signal using the same {OFDM transmitter capable of adjusting size of PN and inserting adjusted PN into OFDM symbol}

The present invention relates to an Orthogonal Frequency Division Multiplexing (OFDM) transmitter and a method for transmitting an OMD signal, and more particularly, Pseudo Noise Sequence (PN) for an OMD signal for transmission. And a guard interval (GI) to insert a time domain synchronous (Time Domain Synchronous (TSS) transmission to perform the transmitter and the OMD signal transmission method.

In general, a broadcasting system of a high definition television (HDTV) can be roughly divided into an image encoder and a modulator. The video encoder compresses digital data of about 1 Gbps obtained from a high quality video source into data of 15 to 18 Mbps. The modulator transmits several tens of Mbps of digital data to the receiver through a limited band channel of 6 to 8 MHz. Digital high-definition television broadcasting adopts a terrestrial simultaneous broadcasting method using a channel of a very high frequency (VHF) / ultra high frequency (UHF) band allocated for conventional television broadcasting.

In Europe, Orthogonal Frequency Division Multiplexing (OFDM), a digital modulation method that achieves a dual effect of improving transmission speed per bandwidth and preventing interference, is adopted as the next generation high-definition television terrestrial broadcasting method.

The OMD method converts a symbol string input in a serial form into parallel data of a predetermined block unit and then multiplexes the parallelized symbols with different subcarrier frequencies. The OMD system uses a multi-carrier, and has a considerable difference from the conventional single carrier. Multiple carriers have orthogonality with each other. Orthogonality means a property in which the product of two carriers becomes '0', which is a requirement for using multiple carriers. The implementation of the UFDM method is accomplished by the Fast Fourier Transform (FFT) and the Inverse Fast Fourier Transform (IFFT). .

On the other hand, the advantages of the OMD method is as follows. The television terrestrial transmission system has channel characteristics in which reflected waves, co-channel interference, and adjacent channel interference affect transmission quality due to signal transmission, and thus design conditions of the transmission system are very demanding. However, the OS has strong characteristics in the multipath. That is, since multiple carriers are used, symbol transmission time can be increased. This is relatively insensitive to the interference signal due to the multipath, so there is little deterioration in performance even for a long time echo signal. In addition, since the existing signal has a strong property, there is little influence on co-channel interference. Due to this characteristic, a single frequency network (SFN) can be constructed. Here, the single frequency network means that one broadcast broadcasts the whole country on one frequency. As a result, co-channel interference becomes very severe, and since the OMD system is strong in such an environment, it can be used. Thus, using a single frequency network can efficiently use a limited frequency resources.

On the other hand, the FM signal is composed of multiple carriers and each carrier has a very small band. Thus, the overall spectral shape is almost square, resulting in a relatively higher frequency efficiency than a single carrier. In addition, the advantages of the UF DM method is that the waveform of the UF DM signal is the same as White Gaussian Noise, so the PAL (Phase Alternation by Line) and SECAM (Sequential Couleur a Memoire) methods are used. Has less interference than other broadcasting services. Accordingly, in the OMD system, the modulation scheme may be different for each carrier, so that hierarchical transmission is possible.

In general, an OPM transmitter which transmits an OFM signal using time domain synchronization, cultivates an OFM signal formed on a frequency axis that provides one service allocated to a predetermined frequency band along a time axis. Degradation performs an inverse discrete Fourier transform. The OPM transmitter is formed by inserting a guard interval (GI) to suppress interference between signals in front of the OFM signal formed along the time axis by an inverse discrete Fourier transform, and inserting synchronization information before the guard period. Send OMD frame.

FIG. 1 is a diagram illustrating an example of a frame structure of an OMD signal formed when an OMD signal is transmitted by using a conventional TDS OMD transmitter.

Looking at the frame structure of the OMD signal, the OMD frame has a form in which the guard interval (GI) and the pseudo noise string (PN) information are inserted into the OFM symbol including data for transmission. The OMD DM symbol is substantially information including data for transmission in an OMD receiver. The guard period (GI) is a period allocated for suppressing interference between the transmitted OMD symbols. PN information is set synchronization information of each of the OMD symbols. This pseudo-noise sequence information is used for synchronization and channel prediction in the OMD receiver.

On the other hand, the ODP symbol included in the frame of the OMD signal transmitted using the conventional OMD transmitter is set such that inverse discrete Fourier transform is performed by multiple subcarriers having 3780 points. In this case, the protection interval GI inserted into the UF DM symbol in which the inverse discrete Fourier transform is performed is 1/6, 1/9, 1/20, of the OMD DM symbol having a size of 3780 points for the inverse discrete Fourier transform. It is inserted into the UF DM symbol in a size corresponding to one of 1/30. In addition, the pseudo noise string (PN) information inserted into the OMD DM inserted with the guard interval is inserted in the size of 255 symbols.

However, the size of the pseudo noise column information of 255 symbols formed in the frame of the conventional OFM signal has a ratio too small compared to the size of the OFM symbol contained in 3780 points of multiple subcarriers. Therefore, in the OMD receiver which receives the OMD signal composed of the frame of the OMD signal of this type, the OMD signal received using the pseudo-noise string information included in the OMD frame is included. There is a difficulty in performing equalization through synchronization and transmission channel estimation. Accordingly, there is a problem that the OMD receiver cannot accurately restore the received OMD signal.

An object of the present invention for solving the above problems, more accurate when performing the synchronization and channel estimation of the OMD signal in the OMD receiver through the pseudo-noise sequence information inserted in the received OMD symbol The present invention provides an OMD transmitter for time domain synchronous transmission that can vary the size of pseudonoise string information inserted into an OFM die symbol so as to recover an FM signal, and a method of transmitting an OMD signal using the same. .

The purpose of the above is to correct the error occurring in the transmission for the OMD DM in the OMD transmitter transmitting and inserting the guard interval and the pseudo-noise sequence information in the OFM symbol for transmission in accordance with the present invention FEC coding unit for performing coding, IDFT unit for performing inverse discrete Fourier transform on the OMD die symbol on which error correction coding is performed, and interference between the OMD die symbols on the ODP DM symbol on which inverse discrete Fourier transform is performed GI insertion section for inserting the guard section to suppress the error, PN insertion section for inserting the pseudo noise string information having a size exceeding 255 symbols into the OSDM symbol inserted with the guard section, and false noise string information inserted. A pulse shaping part for performing pulse shaping filtering on the FDM symbols, and an RF amplifying part for amplifying the RF shaping symbol on which the RF shaping filtering has been performed. It is accomplished by the OFDM transmitter.

Preferably, the GI inserting unit, when inserting the guard interval to the ODP die symbol subjected to the inverse discrete Fourier transform, 1/6, 1/9, 1 / 12, 1/20, 1/30 and 1/12, 1/20, 1/30, 1/36, 1/40 are inserted in the ratio of any one of the modes of the size having the ratio.

Preferably, the PN inserting unit inserts pseudo noise string information having any one size of 500 symbols to 520 symbols and 1000 to 1040 symbols into the OSDM symbol into which the protection interval is inserted. In the present embodiment, the PN insertion unit inserts pseudo-noise string information having any one of 511 symbols and 1023 symbols into the OSDM symbol into which the protection section is inserted.

On the other hand, the above object, according to the present invention, in the transmission method of the FM signal using the OMD transmitter for inserting and transmitting the guard interval and the pseudo-noise sequence information to the OMD signal for transmission, Performing coding for correcting an error occurring in a transmission for the FDM symbol, performing an inverse discrete Fourier transform on the OMD DM with the error correction coding, and performing an inverse discrete Fourier transform. Inserting a guard interval for suppressing interference between the UF DM symbols in the DM symbol, inserting pseudo noise string information having a size exceeding 255 symbols into the UF DM symbol into which the guard interval is inserted, and a pseudo noise sequence Performing pulse shaping filtering on the OMD symbol in which the information is inserted, and performing high frequency amplification on the OFM symbol on which the pulse shaping filtering is performed. Is achieved by a method of transmitting an OMD signal using an OMD transmitter comprising a step.

Preferably, in the step of inserting the guard interval, when the guard interval is inserted into the OPM PD symbol in which the inverse discrete Fourier transform is performed, 1/6, 1 / 9, 1/12, 1/20, 1/30 and 1/12, 1/20, 1/30, 1/36, 1/40 inserted at the ratio of any one of the modes of the size with the ratio do.

Preferably, in the pseudo-noise sequence information insertion step, pseudo-noise sequence information having any one size of 500 symbols to 520 symbols and 1000 to 1040 symbols is inserted into the UF DM symbol into which the guard interval is inserted. In the present embodiment, in the pseudo-noise sequence information insertion step, pseudo-noise sequence information having any one size of 511 symbols and 1023 symbols is inserted into the UF DM symbol into which the guard interval is inserted.

Therefore, the OMD receiver receives the received noise noise sequence information having the size of 511 symbols or 1023 symbols used for equalization through signal synchronization and channel estimation at the receiving side by inserting them into the OMD receiver. The synchronization and channel estimation of the FDM signal can be performed more accurately. Accordingly, the OMD receiver can more accurately restore the received OMD signal.

In addition, since the pseudo-noise sequence information having the size of 511 symbol or 1023 symbol is inserted into the OS signal, more accurate synchronization and channel estimation of the OS signal can be performed on the receiving side, thereby preventing interference between the OS signals. It is possible to reduce the size of the protective section inserted to suppress it. As a result, the transmission rate of the OSDM symbol can be increased.

According to the present invention, an OFM receiver by inserting and transmitting pseudo-noise sequence information having a size of 511 symbols or 1023 symbols used for equalization through signal synchronization and channel estimation at the receiving side, In this case, synchronization and channel estimation of the received OMD signal can be performed more accurately. Accordingly, the OMD receiver can more accurately restore the received OMD signal.

In addition, since the pseudo-noise sequence information having the size of 511 symbol or 1023 symbol is inserted into the OS signal, more accurate synchronization and channel estimation of the OS signal can be performed on the receiving side, thereby preventing interference between the OS signals. It is possible to reduce the size of the protective section inserted to suppress it. As a result, the transmission rate of the OSDM symbol can be increased.

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

Figure 2 is a block diagram showing a preferred embodiment of the FM transmitter in accordance with the present invention.

The FM transmitter includes a FEC coding unit 100, an inverse discrete fourier transform unit 200, a guard interval unit GI unit 300, and a pseudo noise sequence insert unit (PN). 400, a pulse molding unit 500, and an RF (Radio Frequency) amplifier 600.

The FEC coding unit 100 performs coding for correcting an error occurring in the transmission with respect to the OMD symbol for transmission. The IDFT unit 200 performs an inverse discrete Fourier transform on the OMD DM symbol in which the error correction coding is performed in the FEC coding unit 100.

The GI insertion unit 300 inserts a guard interval (GI) for suppressing the interference between the OMD DM symbols to the ODP DM symbols in which the inverse discrete Fourier transform is performed in the IDFT unit 200. In this case, when the GI inserting unit 300 inserts the protection interval into the OFT DM symbol in which the inverse discrete Fourier transform is performed in the IDFT unit 200, 1/6 of the OMD DM having the inverse discrete Fourier transform is performed; It inserts in the ratio of any one mode of size which has the ratio of 1/9, 1/12, 1/20, 1/30.

In addition, when the GI insertion unit 300 inserts the guard interval into the OMD DM symbol in which the inverse discrete Fourier transform is performed in the IDFT unit 200, 1/12 of the OMD DM having the inverse discrete Fourier transform is performed; It is also possible to insert in the ratio of any one of the modes of the size having the ratio of 1/20, 1/30, 1/36, 1/40. Accordingly, the transmission rate of the OMD DM symbol included in the frame of the OMD signal can be increased.

The PN inserting unit 400 inserts pseudo noise string (PN) information into the OMD DM symbol into which the guard interval of the corresponding size is inserted according to the determined ratio mode. In this case, the PN inserting unit 400 inserts pseudo noise string information having a size exceeding 255 symbols into the OMD DM inserted into the protection section. Preferably, the PN inserting unit 400 inserts pseudo-noise string information having any one size of 511 symbols and 1023 symbols into the OMD DM inserted with the guard interval.

The pulse shaping unit 500 performs pulse shaping filtering according to a roll off factor set for the UF DM symbol in which pseudo noise string information having any one size set among 511 symbols and 1023 symbols is inserted. .

The RF amplification unit 600 amplifies the RF DMP, in which the pulse shaping filtering is performed in the pulse shaping unit 500, to transmit the OMD DM signal through the transmission channel to the OPM receiver through the antenna 700.

Therefore, the OMD receiver receives the received noise noise sequence information having the size of 511 symbols or 1023 symbols used for equalization through signal synchronization and channel estimation at the receiving side by inserting them into the OMD receiver. The synchronization and channel estimation of the FDM signal can be performed more accurately. Accordingly, the OMD receiver can more accurately restore the received OMD signal.

In addition, since the pseudo-noise sequence information having the size of 511 symbol or 1023 symbol is inserted into the OS signal, more accurate synchronization and channel estimation of the OS signal can be performed on the receiving side, thereby preventing interference between the OS signals. It is possible to reduce the size of the protective section inserted to suppress it. As a result, the transmission rate of the OSDM symbol can be increased.

FIG. 3 is a diagram illustrating an example of a frame structure of an OMD signal formed by FIG. 2.

According to the drawing, the frame of the OMD signal comprises an OMD symbol including data for transmission, a guard interval (GI) inserted into the OMD symbol and pseudo noise string (PN) information.

The OMD DM symbol transmitted using the OMD transmitter according to the present embodiment is set such that inverse discrete Fourier transform is performed by multiple subcarriers having 'N' points. At this time, types of 'N' points include 3780 points, 2048 points, 4096 points, and 8192 points. Here, the mode of the multiple subcarriers having 2048 points is called 2K mode, the mode of the multiple subcarriers having 4096 points is 4K mode, and the mode of multiple subcarriers having 8192 points is called 8K mode.

The guard intervals are 1/6, 1/9, 1/12, 1/20, 1/30 of the UF DM symbols according to the size mode for the UF DM symbols included in the multiple subcarriers of 'N' points. It is inserted into any one of the size modes of the mode having the ratio or the mode having the ratio of 1/12, 1/20, 1/30, 1/36, 1/40.

4 is a flowchart illustrating a preferred embodiment of a method of transmitting an OMD signal using an OMD transmitter according to the present invention.

First, the FEC coding unit 100 performs coding for correcting an error occurring in transmission with respect to the OFM symbol for transmission (S100). The IDFT unit 200 performs an inverse discrete Fourier transform on the OSDM symbol on which error correction coding is performed (S120).

The GI insertion unit 300 inserts a guard interval GI for suppressing the interference between the FM DM symbols in the OS DM symbol on which the inverse discrete Fourier transform has been performed (S140). When the GI insertion unit 300 inserts a protection interval into the OSF symbol in which the inverse discrete Fourier transform is performed, 1/6, 1/9, 1/12, of the OSF symbol in which the inverse discrete Fourier transform is performed. It inserts in the ratio of any one mode of the size which has the ratio of 1/20, 1/30 and 1/12, 1/20, 1/30, 1/36, 1/40. Accordingly, the transmission rate of the OMD DM symbol included in the frame of the OMD signal can be increased.

The PN insertion unit 400 inserts pseudo noise string (PN) information having a size exceeding 255 symbols into the OMD DM symbol into which the guard interval of the corresponding size is inserted according to the determined ratio mode (S160). Preferably, the PN inserting unit 400 inserts pseudo-noise string information having any one size of 511 symbols and 1023 symbols into the OMD DM inserted with the guard interval.

The pulse shaping unit 500 performs pulse shaping filtering according to a roll off factor set for the UF DM symbol in which pseudo noise string information having any one size set among 511 symbols and 1023 symbols is inserted. (S180). The RF amplifier 600 amplifies a high frequency in order to transmit the UF DM symbol on which the pulse shaping filtering is performed to the UF DM receiver through a transmission channel (S200).

Therefore, the OMD receiver receives the received noise noise sequence information having the size of 511 symbols or 1023 symbols used for equalization through signal synchronization and channel estimation at the receiving side by inserting them into the OMD receiver. The synchronization and channel estimation of the FDM signal can be performed more accurately. Accordingly, the OMD receiver can more accurately restore the received OMD signal.

In the above described and illustrated with respect to the preferred embodiment of the present invention, the present invention is not limited to the specific preferred embodiment described above, without departing from the gist of the invention claimed in the claims in the art Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

1 is a diagram illustrating an example of a frame structure of an OMD signal formed when an OMD signal is transmitted using a conventional time domain synchronous OMD transmitter;

Figure 2 is a block diagram showing a preferred embodiment of the FM transmitter in accordance with the present invention,

FIG. 3 is a diagram showing an example of a frame structure of an OFM signal formed by FIG. 2; and

4 is a flowchart illustrating a preferred embodiment of a method of transmitting an OMD signal using an OMD transmitter according to the present invention.

Explanation of symbols on the main parts of the drawings

100: FEC coding part 200: IDFT part

300: GI insert 400: PN insert

500: pulse molding part 600: RF amplification part

700: antenna

Claims (11)

In the OPM transmitter, An FEC coding unit which performs coding on input data for transmission; An inverse discrete Fourier transform unit (IDFT unit) for performing an Inverse Discrete Fourier Transform for converting the coded data into OFM die symbols; A PN insertion unit for inserting pseudo-noise string information having a variable size according to a mode into the OMD DM symbol on which the inverse discrete Fourier transform is performed; A pulse shaping unit for performing pulse shaping filtering on the OMD DM symbols into which the pseudo noise string information is inserted; And It includes; RF up-conversion unit for RF conversion of the molded-filtered FM signal, including; And the PN inserting unit inserts pseudo-noise sequence information having a size of at least 511 symbols in a predetermined mode in the OMD DM symbol. delete The method of claim 1, The PN insert portion, And inserting the pseudo-noise sequence information having any one size from 1000 symbols to 1040 symbols in a predetermined mode. The method of claim 1, The PN insert portion, And the pseudo-noise sequence information having a size of 511 symbols in a predetermined mode is inserted into the OMD DM symbol. In a receiving system for receiving a broadcast signal transmitted from the transmitting side, A receiver configured to receive a broadcast signal including a PN sequence; A synchronization unit for performing symbol timing and frequency synchronization using the PN sequence; And And a demodulator for demodulating the synchronized broadcast signal. The PN sequence has a size that varies with mode and has a size of at least 511 symbols in a given mode. The method of claim 5, The transmitting side, An FEC coding unit which performs coding on input data for transmission; An inverse discrete Fourier transform unit (IDFT unit) for performing an Inverse Discrete Fourier Transform for converting the coded data into OFM die symbols; A PN insertion unit for inserting pseudo-noise string information into the UF DM symbol on which the inverse discrete Fourier transform is performed; A pulse shaping unit for performing pulse shaping filtering on the OMD DM symbols into which the pseudo noise string information is inserted; And And a RF up-conversion unit for RF converting the molded-filtered FM signal. The method of claim 6, The PN sequence is Receiving system having a size of 511 symbols in a predetermined mode. delete In an OFDM receiver, An ADC unit for converting a signal received from the tuner into a digital signal; A down conversion unit for down converting the signal or signal received from the ADC unit into a baseband signal; A synchronization unit for performing symbol timing and frequency synchronization using the PN sequence inserted into the received signal; A demultiplexer for separating and outputting the signal received from the synchronizer into the PN sequence and the data block; An FFT unit configured to perform fast Fourier transform on the data block output from the demultiplexer and output the converted data block; And And an FEC unit for detecting and correcting an error of the converted data block according to a preset error detection method. Wherein the PN sequence has a size that varies with mode and has a size of at least 511 symbols in a given mode. 10. The method of claim 9, The PN sequence is The OMD receiver having a size of 511 symbols in a predetermined mode. In the OFDM receiving module, An ADC unit for converting a signal received from the tuner into a digital signal; A synchronization unit for performing symbol timing and frequency synchronization using the PN sequence inserted into the received signal; A demultiplexer for separating and outputting the signal received from the synchronizer into the PN sequence and the data block; An FFT unit configured to perform fast Fourier transform on the data block output from the demultiplexer and output the converted data block; And And an FEC unit for detecting and correcting an error of the converted data block according to a preset error detection method. And the PN sequence has a size that varies with mode and has a size of at least 511 symbols in a given mode.

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