KR20100051602A - Ofdm transmitter, ofdm receiver, and transmitting, receiving method thereof - Google Patents

Abstract

PURPOSE: An OFDM(Orthogonal Frequency Division Multiplexing) transmitter, a receiver, a receiving module and a transceiving method thereof are provided to proceed synchronization/channel estimation about a received OFDM signal in the OFDM receiver more accurately by inserting Pseudo Noise sequence information with a size of 511 symbol or 1023 symbol into an OFDM symbol in the receiving side. CONSTITUTION: An FEC(Forward Error Correction) coding unit(100) proceeds coding about an input data. An IDFT(Inverse Discrete Fourier Transform)(200) converts the coded data into an OFDM symbol. A PN(Pseudo Noise sequence) insertion unit(400) inserts PN sequence into the OFDM symbol. The PN sequence has at least 511 symbol size. A pulse forming unit(500) proceeds pulse forming filtering about the OFDM symbol. An RF(Radio Frequency) up-conversion part(600) converts changes the OFDM symbol into an RF signal.

Description

UFDM transmitter, receiver, receiving module and method for transmitting / receiving the same {OFDM transmitter, OFDM receiver, and transmitting, receiving method}

The present invention relates to an Orthogonal Frequency Division Multiplexing (OFDM) transmitter, a receiver, a method for transmitting the same, and a method for receiving the same. More specifically, the present invention relates to an OMD transmitter and receiver for inserting and transmitting pseudo noise string information into a transmission signal. It relates to a receiving module and a method for transmitting and receiving the same.

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.

By the way, the size of the pseudo-noise sequence information of 255 symbols formed in the frame of the conventional OMD 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, a receiver, a receiving module, and a method for transmitting / receiving the size of pseudonoise string information inserted in an OFM symbol so as to recover an FDM signal.

An OFDM transmitter according to an embodiment of the present invention for achieving the above object, the FEC coding unit for coding the input data, the inverse discrete Fourier transform (IDFT) unit for converting the coded data into OFDM symbols A PN inserter inserting a PN sequence having at least 511 symbol size into the OFDM symbol, a pulse shaping unit performing pulse shaping filtering on the OFDM symbol into which the PN sequence is inserted, and RF shaping the shaping filtered OFDM symbol It includes an RF up-conversion unit for converting into a (radio frequency) signal.

Here, the length of the existing PN sequence may be 511 symbols.

The PN inserter may insert a PN sequence having a size that varies according to a mode and insert a PN sequence having the 511 symbol size in a predetermined mode.

On the other hand, the OFDM transmission method according to an embodiment of the present invention, performing coding on the input data, performing an inverse discrete Fourier transform for converting the coded data into OFDM symbols, at least 511 to the OFDM symbol Inserting a PN sequence having a symbol size, performing pulse shaping filtering on the OFDM symbol into which the PN sequence is inserted, and converting the shaped OFDM symbol into an RF signal.

In this case, the length of the PN sequence may be 511 symbols.

The inserting of the PN sequence may include inserting a PN sequence having a variable size according to a mode, and inserting a PN sequence having the 511 symbol size in a predetermined mode.

An OFDM receiver for receiving a broadcast signal transmitted from a transmitter according to an embodiment of the present invention includes a receiver for receiving a broadcast signal having a PN sequence having at least 511 symbol sizes, and a PN sequence inserted into the broadcast signal. And a demodulator configured to perform symbol timing and frequency synchronization, and a demodulator configured to demodulate the synchronized broadcast signal.

Here, the PN sequence may have a size of 511 symbols.

The receiver may receive a broadcast signal having a PN sequence having a size that varies according to a mode, and receive a broadcast signal having a PN sequence having a 511 symbol size in a predetermined mode.

On the other hand, OFDM reception method for receiving a broadcast signal transmitted from the transmitting side according to an embodiment of the present invention, receiving a broadcast signal having a PN sequence having at least 511 symbol size, PN sequence inserted into the broadcast signal Performing symbol timing and frequency synchronization by using a second terminal; and demodulating the synchronized broadcast signal.

Here, the PN sequence may have a size of 511 symbols.

The receiving of the broadcast signal may include receiving a broadcast signal having a PN sequence having a size varying according to a mode, and receiving a broadcast signal having a PN sequence having a 511 symbol size in a predetermined mode.

On the other hand, the OFDM receiving module for receiving a broadcast signal transmitted from the transmitting side according to an embodiment of the present invention, a receiving unit for receiving a broadcast signal having a PN sequence having at least 511 symbol size, PN inserted into the broadcast signal And a demodulation unit for demodulating the synchronized broadcast signal and a synchronization unit for performing symbol timing and frequency synchronization using a sequence.

Here, the PN sequence may have a size of 511 symbols.

The receiving unit may receive a broadcast signal having a PN sequence having a size varying according to a mode, and receive a broadcast signal having a PN sequence having a 511 symbol size in a predetermined mode.

On the other hand, the transmitter according to an embodiment of the present invention, the FEC coding unit for coding the input data, an inverse discrete Fourier transform (IDFT) unit for converting the coded data into a symbol, at least 511 to the transformed symbol A PN inserting unit for inserting a PN sequence having a symbol size, a pulse molding unit for performing pulse shaping filtering on the symbol into which the PN sequence is inserted, and an RF up-converting unit for transforming the shaping filtered symbol into an RF (radio frequency) signal It includes a conversion unit.

Wherein the PN sequence has a size of 511 symbols.

On the other hand, the receiver receiving the broadcast signal transmitted from the transmitting side, the receiver for receiving a broadcast signal having a PN sequence having at least 511 symbol size, and performs the symbol timing and frequency synchronization using the PN sequence inserted into the broadcast signal And a demodulator for demodulating the synchronized broadcast signal.

Here, the PN sequence may have a size of 511 symbols.

In addition, the receiving module for receiving a broadcast signal transmitted from the transmitting side according to an embodiment of the present invention, a receiving unit for receiving a broadcast signal having a PN sequence having at least 511 symbol size, PN sequence inserted into the broadcast signal It includes a synchronization unit for performing symbol timing and frequency synchronization using a demodulation unit for demodulating the synchronized broadcast signal.

Here, the PN sequence may have a size of 511 symbols.

According to the present invention, in the OMD receiver by inserting and transmitting pseudo-noise string information having a size of 511 symbols or 1023 symbols used for equalization through signal synchronization and channel estimation at the receiving side, It is possible to more accurately perform synchronization and channel estimation on the received OMD signal. 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.

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.

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 OSDM symbol transmitted using the OSDM transmitter according to the present embodiment is set such that an 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.

100: FEC coding part 200: IDFT part
300: GI insert 400: PN insert
500: pulse molding part 600: RF amplification part
700: antenna

Claims (21)

An FEC coding unit which performs coding on input data;
An inverse discrete Fourier transform (IDFT) unit for converting the coded data into OFDM symbols;
A PN inserter inserting a PN sequence having at least 511 symbol size into the OFDM symbol;
A pulse shaping unit performing pulse shaping filtering on the OFDM symbol into which the PN sequence is inserted; And
And an RF up-conversion unit for converting the molded-filtered OFDM symbol into a radio frequency (RF) signal. The method of claim 1,
And the length of the PN sequence is 511 symbols. The method of claim 1,
The PN insertion unit,
Insert a PN sequence with a size that varies with mode,
And a PN sequence having the 511 symbol size in a predetermined mode. In the OFDM transmission method,
Performing coding on input data;
Performing an Inverse Discrete Fourier Transform to transform the coded data into OFDM symbols;
Inserting a PN sequence having at least 511 symbol size into the OFDM symbol;
Performing pulse shaping filtering on the OFDM symbol into which the PN sequence is inserted; And
And converting the shaped OFDM symbol into an RF signal. The method of claim 4, wherein
And a length of the PN sequence is 511 symbols. The method of claim 4, wherein
Inserting the PN sequence,
Insert a PN sequence with a size that varies with mode,
And a PN sequence having the 511 symbol size is inserted in a predetermined mode. An OFDM receiver for receiving a broadcast signal transmitted from a transmitting side,
A receiver configured to receive a broadcast signal having a PN sequence having at least 511 symbol sizes;
A synchronization unit for performing symbol timing and frequency synchronization using the PN sequence inserted into the broadcast signal; And
And a demodulator for demodulating the synchronized broadcast signal. The method of claim 7, wherein
And the PN sequence has a size of 511 symbols. The method of claim 7, wherein
The receiving unit,
Receives a broadcast signal with a PN sequence having a variable size according to the mode,
And a broadcast signal having a PN sequence having the 511 symbol size in a predetermined mode. In the OFDM receiving method for receiving a broadcast signal transmitted from the transmitting side,
Receiving a broadcast signal having a PN sequence having at least 511 symbol size;
Performing symbol timing and frequency synchronization using a PN sequence inserted into the broadcast signal; And
Demodulating the synchronized broadcast signal. The method of claim 10,
And the PN sequence has a size of 511 symbols. The method of claim 10,
Receiving the broadcast signal,
Receives a broadcast signal with a PN sequence having a variable size according to the mode,
And a broadcast signal having a PN sequence having the 511 symbol size in a predetermined mode. In the OFDM receiving module for receiving a broadcast signal transmitted from the transmitting side,
A receiving unit for receiving a broadcast signal having a PN sequence having at least 511 symbol sizes;
A synchronization unit for performing symbol timing and frequency synchronization using the PN sequence inserted into the broadcast signal; And
And a demodulation unit for demodulating the synchronized broadcast signal. The method of claim 13,
And the PN sequence has a size of 511 symbols. The method of claim 13,
The receiving unit,
Receives a broadcast signal with a PN sequence having a variable size according to the mode,
And a broadcast signal having a PN sequence having the 511 symbol size in a predetermined mode. An FEC coding unit which performs coding on input data;
An Inverse Discrete Fourier Transform (IDFT) unit for converting the coded data into symbols;
A PN insertion unit inserting a PN sequence having at least 511 symbol sizes into the converted symbols;
A pulse shaping unit performing pulse shaping filtering on the PN sequence-embedded symbol; And
And an RF up-conversion unit for converting the shaped-filtered symbol into a radio frequency (RF) signal. 17. The method of claim 16,
Wherein the PN sequence has a size of 511 symbols. A receiver for receiving a broadcast signal transmitted from a transmitting side,
A receiver configured to receive a broadcast signal having a PN sequence having at least 511 symbol sizes;
A synchronization unit for performing symbol timing and frequency synchronization using the PN sequence inserted into the broadcast signal; And
And a demodulator for demodulating the synchronized broadcast signal. 19. The method of claim 18,
And the PN sequence has a size of 511 symbols. In the receiving module for receiving a broadcast signal transmitted from the transmitting side,
A receiving unit for receiving a broadcast signal having a PN sequence having at least 511 symbol sizes;
A synchronization unit for performing symbol timing and frequency synchronization using the PN sequence inserted into the broadcast signal; And
And a demodulation unit for demodulating the synchronized broadcast signal. The method of claim 20,
The receiving module, characterized in that the PN sequence has a size of 511 symbols.

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