HK1109969A - Single carrier transmission system capable of reducing signal distortion and method thereof - Google Patents

Description

Single carrier transmission system capable of reducing signal distortion and method thereof

The present application is a divisional application of an invention patent application having an application date of 30/9/2003, an application number of 03139100.1, entitled "single carrier transmission system and method for reducing signal distortion".

Technical Field

The present invention relates generally to a single carrier transmission system and a method thereof, and more particularly, to a single carrier transmission system and a method thereof capable of improving reliability of a transmitted signal.

Background

In the era of communication multimedia, computers and broadcasting, countries around the world are constantly digitizing analog type broadcasts. Particularly in developed countries such as the united states, europe, and japan, a digital broadcasting system using satellites has been developed and put into practical use. With the rapid development, different standards for digital broadcasting have been proposed in countries, respectively.

On 24.12.1996, the Federal Communications Commission (FCC) in the united states passed the digital television standard of the advanced television systems committee as the broadcast standard for the next generation of TV. All terrestrial broadcast operators must comply with the ATSC standard in relation to the video/audio compression, packet data transmission architecture, modulation and transmission system specifications. Only the specification of the video format is not announced (stated) but is decided by the industry.

According to the ATSC standard, the video compression scheme employs the ISO/IEC IS13812-2 standard for moving Picture experts group-2 (MPEG-2). This standard has been adopted as a standard for all digital broadcasting types around the world. The audio compression scheme employs the digital audio compression-3 (AC-3) standard proposed by Dolby. The ISO/IEC IS13812 standard for MPEG-2 systems has been adopted as a multiplexing method. This multiplexing method is used in european proposals together with video compression schemes. 8-vestigial sideband (8-VSB) is adopted as a method of modulation and transmission. The VSB method is proposed for digital television broadcasting, using a frequency band of 6MHz to obtain a high-band-efficiency data transmission rate of 19.39Mbps with a simple structure. This is also designed to minimize interference with the broadcast channels of the National Television Standards Committee (NTSC) existing broadcast system. This method uses a pilot signal, a segment sync signal, and a field sync signal in order to stably operate even in a noise environment. Further, to avoid errors, the method uses reed-solomon (RS) codes and Trellis (Trellis) coding.

The ATSC digital television standard is for transmitting high quality video, audio and additional data in a 6MHz band using a single carrier VSB method, and supports a simultaneous terrestrial broadcast mode and a high data rate cable broadcast mode. The main aspect of the method is the 8-VSB modulation method, which is a modified form of the existing analog VSB method, and is capable of performing digital signal modulation.

Fig. 1 is a schematic block diagram illustrating a digital broadcasting system according to the ATSC standard. Referring to fig. 1, the digital broadcasting system includes a scrambler 10, a Forward Error Correction (FEC) unit 20, a Multiplexer (MUX)30, a pilot insertion unit 40, a modulation unit 50, and a Radio Frequency (RF) converter 60. The FEC unit 20 includes a reed-solomon (RS) encoder 21, an interleaver 23, and a trellis encoder 25.

The scrambler 10 is called a data randomizer, and performs a randomization operation on a transmitted data signal, thereby preventing a problem of loss of a synchronization signal due to a repeating word such as 00000000b or 11111111b during the transmission of synchronous data. The scrambler 10 changes the bytes of each data signal in a predetermined pattern and this process is reversed so that the exact values are recovered at the receiving end.

The RS encoder 21 is an FEC structure added to the input data stream. FEC is one of the techniques for correcting errors occurring during data transmission. Atmospheric noise, multipath frequencies, signal attenuation, and receiver non-linearities are the causes of bit errors. The RS encoder 21 adds 20 bytes at the end of 187 bytes when the transmitted data is in the MPEG-II transport stream. This added 20 bytes is called the reed-solomon parity bytes. The receiver compares the received 187 bytes with the 20 parity bytes, thereby determining the accuracy of the received data. In case an error is detected, the receiver finds the location of the error and recovers the original signal by correcting the distorted bytes. Errors of up to 10 bytes per stream can be recovered by using this method. However, errors of more than 10 bytes are not recoverable, and thus, the entire stream is discarded.

The interleaver 23 interleaves the order of the data streams, thereby dispersing the transmitted data on a time axis. By doing so, the transmitted data becomes immune (insensitive) to interference. By dispersing the transmitted data, signals in other frequency bands are preserved when noise occurs at a particular location. The receiver reverses the above-described processing, thereby restoring the dispersed transmission signal to exactly the same as the original signal.

Unlike the RS encoder 21, the trellis encoder 25 has a different type of FEC structure. And, unlike the RS encoder 21 constituting the entire MPEG-II stream, the trellis encoder 25 performs encoding in consideration of the influence of time. This is called a convolutional code. The trellis encoder 25 divides the 8-bit byte into 4 2-bit words. The 2-bit word is compared with the previous word and a 3-bit binary code is generated with the purpose of describing the change from the previous word to the current word. The 3-bit code is transmitted to the 8-level symbols of the 8-VSB instead of the original 2-bit word (3-bit-8-level). Accordingly, the 2-bit word input to the trellis encoder 25 is converted and output as a 3-bit signal. Because of this feature, 8-VSB is sometimes referred to as an 2/3 rate encoder. The advantage of trellis coding is that the signal can be tracked in time units, thereby clearing error information.

After trellis encoding by the trellis encoder 25, the multiplexer 30 inserts a segment sync and a frame sync in the transmission signal. The pilot insertion unit 40 inserts an ATSC pilot into the transmission signal into which the segment sync and the frame sync are inserted. Here, immediately after modulation is completed, 1.25v with a slight dc offset is applied to the 8-VSB baseband signal. When this occurs, a slight residual carrier appears at the zero frequency point of the modulation spectrum. This generated residual carrier is referred to as the "ATSC pilot.

The modulation unit 50 modulates the signal received from the pilot insertion unit 40 by using 8-VSB modulation. Digital modulation is a process of converting one of the phase, amplitude, and frequency of a carrier wave into a digital signal. Among them, Phase Shift Keying (PSK) is a process of changing a phase according to a digital value. The most basic PSK is binary phase shift keying with a phase separation of 180 ° between the '0' and '1' carriers of the 1-bit signal. Quadrature Phase Shift Keying (QPSK) is a process of having a phase interval of 90 ° with 42 bits corresponding to 1 symbol. A value obtained by multiplying the cosine wave by the BPSK signal and a value obtained by multiplying the sine wave by the BPSK signal are added and transmitted. 8-PSK transmits a single symbol with 8-level signals, the 8-level signals having 3 bits and a phase interval of 45 °, respectively. Since 8-PSK transmits three times BPSK's information over the same bandwidth, 8-PSK has much higher frequency efficiency. However, it is susceptible to noise due to the narrow spacing between the respective phases, and therefore requires very high (much) power to maintain the same transmission error rate.

Amplitude keying (ASK) is a process of changing the amplitude of a carrier wave. ASK is almost similar to Amplitude Modulation (AM) except that the modulated signals are not sequential, but rather are in a predetermined number of amplitude levels. For example, the modulated wave has 8 levels through ASK processing of 3-bit information, and the modulated wave has 16 levels through ASK processing of 4-bit information. The modulated wave signal is a double sideband signal.

Amplitude phase keying is a way of transmitting information on both the carrier and the amplitude of the carrier. Quadrature amplitude modulation changes the quadrature relationship of the carriers, combines the carriers, and transmits the carriers. For example, the 16 QAMs may transmit BPSK4 times information over the same bandwidth. However, since the codes are respectively at narrow intervals, high power is required to maintain the same transmission error rate.

The spectrum of the ASK signal is a double sideband signal, and therefore, it cannot be said that the channel is satisfactorily utilized. Clipping these signal bands to vestigial sideband will produce VSB signals. For example, 3 bits of digital information are represented by 8 levels. The 8-VSB signal is then generated by the band slicing operation of ASK processing and VSB filtering. The conclusion is that: the 8-VSB signal is very similar to the analog VSB except that it may have 8 signals.

The rf converter 60 rf-converts the modulated signal and transmits the modulated signal through an antenna.

The ATSC data segment is made up of 187 bytes and 20 bytes of the original MPEG-II data stream. After trellis encoding, 207 bytes of the segment are changed into 828(207 × 4), 8-level symbol stream.

The segment sync signal is 4 1-byte pulses that are repeatedly added to the beginning of the data segment and the sync byte used to replace the original MPEG-II transport stream. The receiver is able to distinguish the repeated pattern of segment sync signals from the completely random data and is also able to accurately recover the clock even when noise and interference are at levels that do not allow the data to recover itself. The segments of the transmission signal to which the segment sync signal (i.e., segment sync) is assigned are shown in fig. 2. As shown, the segment of the transmission signal includes a segment synchronization signal of 4 symbols, 3 Pseudo Noise (PN) sequences of 63 symbols, respectively, a transmission pattern of 24 symbols, 96 reserved symbols, and 12 pre-code symbols. The PN sequence is a synchronization information sequence used for synchronization and channel estimation of the receiver. The PN sequence is generated by a PN sequence generating unit (not shown) and inserted into the transmission signal by the multiplexer 30.

Fig. 3 is a view showing a structure of a frame of ATSC data. Referring to fig. 3, a field of ATSC data includes 313 consecutive data segments, and an ATSC field sync (i.e., field sync) becomes a field data segment. An ATSC data frame is composed of 2 ATSC data fields.

The ATSC data field is repeated at a time interval of 24.2ms, similar to the 16.7ms vertical interval for NTSC. The segment sync has a well-known data symbol pattern and is used in the receiver to remove ghosts. More specifically, ghost removal is achieved by comparing error-containing signals to fields synchronously and using the resulting error vector to adjust the characteristics of a ghost-removing equalizer.

Fig. 4 is a view for comparing constellations (constellations) of single carrier modulation such as ATSC, respectively. When the frequency fs of the samples is 7.14MHz, the VSB modulation divides the digital signal into an in-phase (I) component and a quadrature (Q) component, and transmits data only to the component in the in-phase at a clock of 2fs (═ 14.28 MHz). Unlike VSB modulation, the OQAM modulation alternately transmits data to an (I) component and a (Q) component at a clock of 2fs (═ 14.28 MHz). Fig. 5 shows sample data according to these two modulations, respectively.

In a single carrier transmission system having a frame structure in which a PN sequence is combined with data, such as a single carrier transmission system according to the ATSC standard, the PN sequence and the data of a frame or field sync unit are transmitted according to the same modulation method. Such a transmission system uses only one single carrier modulation method and is therefore unreliable for variations caused by burst noise in a channel environment.

In U.S. patent application No. 09/962,263 (publication No. US2002041608), there is disclosed a VSB reception system, comprising: a tuner tuning an RE signal transmitted from the VSB transmitter; a VSB demodulator demodulating a signal output from the tuner; a demultiplexer demultiplexing the demodulated signal into ATSC data and additional data; a decoder for decoding the ATSC data; and a derandomizer for derandomizing the decoded data.

Disclosure of Invention

Accordingly, an object of the present invention is to provide a single carrier transmission system and a method thereof, which can appropriately cope with channel environment variation due to burst noise and can use a plurality of types of single carrier modulation.

To achieve the above object, a single carrier transmission system is provided. The single carrier transmission system includes: a scrambling unit for scrambling a TS (transport stream) to be transmitted; an FEC unit, which is used for carrying out forward error correction on the TS after the scrambling code from the scrambling code unit to form a coded TS; a modulation information generating unit for generating modulation information on a modulation method; a multiplexer unit for receiving the encoded TS, the segment sync information, the field sync information, and the modulation information, and thereby inserting the segment sync information and/or the field sync information and the modulation information to a start position of the encoded TS according to a control signal to form a multiplexed TS including one frame sync region and a data region; a pilot inserting unit for inserting a pilot into the multiplexed TS; a modulation unit for modulating a frame synchronization region and a data region in the pilot-inserted TS output from the pilot insertion unit using corresponding modulation methods, respectively, according to modulation information in the pilot-inserted TS; and a radio frequency converter for performing radio frequency conversion on the modulated TS from the modulation unit.

According to another aspect of the present invention, a single carrier transmission method is provided. The single carrier transmission method comprises the following steps: scrambling a TS (transport stream) to be transmitted; forward error correcting the scrambled TS from the scrambling unit to form a coded TS; generating modulation information on a modulation method; receiving the encoded TS, the segment sync information, the field sync information, and the modulation information, and thereby inserting the segment sync information and/or the field sync information and the modulation information to a start position of the encoded TS according to a control signal to form a multiplexed TS including one frame sync region and a data region; inserting a pilot into said multiplexed TS; modulating a frame synchronization region and a data region in the pilot-inserted TS output from the pilot insertion unit respectively using corresponding modulation methods according to modulation information in the pilot-inserted TS; and performing radio frequency conversion on the modulated TS at the modulating step.

Drawings

The above objects and features of the present invention will become more apparent by describing embodiments of the present invention with reference to the attached drawings, in which:

fig. 1 is a block diagram schematically illustrating a digital broadcast transmission system according to the ATSC standard;

fig. 2 is a view showing a section of a transmission signal in fig. 1;

fig. 3 is a view showing a frame structure of the transmission signal in fig. 1;

fig. 4 is a view for comparing constellations of single carrier modulations;

fig. 5 is a view showing sample data according to respective modulations in fig. 4;

fig. 6 is a block diagram schematically showing a digital broadcast transmission system according to the present invention;

fig. 7 is a flowchart illustrating a single carrier modulation method in fig. 6;

fig. 8 is a view showing sample data according to single carrier modulation performed on the digital broadcast transmission system in fig. 6.

Detailed Description

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

Fig. 6 is a block diagram schematically showing a digital broadcast transmission system according to the present invention. Referring to fig. 6, the digital broadcasting transmission system includes a scrambler 100, a Forward Error Correction (FEC) unit 110, a Multiplexer (MUX)120, a pilot inserting unit 130, a region determining unit 141, a modulating unit 143, a modulation information generating unit 145, and a Radio Frequency (RF) converter 150. The FEC unit 110 includes a reed-solomon (RS) encoder 111, an interleaver 113, and a trellis encoder 115.

During the synchronous data transmission, the scrambler 100 randomly operates on the transmitted data signal in order to prevent problems such as loss of the synchronous signal due to repeated numbers such as 00000000b or 11111111b during the synchronous data transmission. The scrambler 100 changes the bytes of the data signal in a predetermined pattern, which is processed back at the receiver to recover the exact original data.

The FEC unit 110 corrects errors with respect to the input data stream. Since the RS encoder 111, the interleaver 113, and the trellis encoder 115 are constructed and operated in the same manner as in the digital broadcasting system of the ATSC standard, further explanation will be omitted herein.

The modulation information generating unit 145 generates modulation information on a modulation method.

A Pseudo Noise (PN) sequence generating unit (not shown) generates a PN sequence, i.e., it generates synchronization information for synchronization between the transmitter and the receiver, and then transmits the generated PN sequence to the MUX 120. Here, the "transmitter" refers to a receiving end equipped with a digital broadcasting transmission system for transmitting digital broadcasting using a single carrier scheme, and the "receiver" refers to a receiving end for receiving digital broadcasting transmitted using a single carrier scheme.

After trellis encoding performed by the trellis encoder 115, the MUX120 receives a transmission signal (i.e., an encoded TS), segment sync information, field sync information, and modulation information, and inserts segment sync and PN sequences and modulation information generated at the modulation information generation unit 145 to the head portion of the encoded TS. Here, a PN sequence may be used as field synchronization. As another example, the MUX120 inserts segment sync and modulation information into a header portion of the encoded TS. By doing so, the MUX120 forms a multiplexed TS including a frame sync area and a data area.

The modulation information represents a modulation method of each region and is transmitted to the receiver through the frame synchronization region. Therefore, the receiver can effectively cope with the variation of the modulation method of the transmitter.

According to one embodiment of the present invention, the frame synchronization region sequence includes: segment sync symbols, field sync symbols, and modulation information symbols, and the data region includes the encoded TS.

According to another embodiment of the present invention, the frame synchronization region sequence comprises: a field synchronization symbol and a modulation information symbol, and the data region includes the encoded TS.

The pilot insertion unit 130 inserts a pilot in the transmission signal into which at least the segment sync and the PN sequence have been inserted. Here, the pilot refers to a residual carrier occurring at a zero frequency point (zero frequency point) of the modulation spectrum.

The region determining unit 141 determines a frame synchronization region and a data region of the transmission signal output from the pilot inserting unit 130 according to control information corresponding to modulation information.

As an example, the single carrier transmission system of the present invention has a frame structure in which the frame synchronization region is merged with the data region. In this system, the frame synchronization region has a series of, for example, 3 PN sequences, each of which is composed of 511 symbols, followed immediately by a control bit and the remaining bits. The series of 3 PN sequences is referred to as a training symbol. Among the bits transmitted through the communication line for data transmission, the control bit is a bit for control, such as a parity bit, a start bit, or an end bit. The remaining bits refer to the areas prepared for time axis variation, bit rate compression and error correction.

The data region includes a payload region and a tail symbol region. The payload is a region for information related to an upper layer and can be used for communication services. The tail symbols are used for extra information and are referred to as 'tail' symbol regions because they are provided at the last node of the frame.

In order to determine the frame synchronization region and the data region, the region determining unit 141 counts symbols of the transmission signal in the frame unit concerned, and compares the counted value with a predetermined number of symbols for the respective regions.

After the frame synchronization region and the data region are determined by region determining section 141, modulating section 143 modulates the regions in accordance with the modulation scheme of the single carrier. For example, VSB modulation may be predetermined for the frame sync region of the transmission signal, and QAM modulation may be predetermined for the modulated data region. In this case, the modulation unit 143 modulates the frame sync region according to VSB modulation, and modulates the data region according to QAM modulation. Further, the modulation unit 143 may use OQAM and QAM, VSB and OQAM, QAM and OQAM, OQAM and VSB, and QAM and VSB modulation for the frame sync region and the data region, respectively. Preferably, the frequency of QAM sampling is half of OQAM, since QAM transmits data to both the I and Q components.

A Radio Frequency (RF) converter 150 converts the modulated transmission signal into a radio frequency and transmits the converted signal through an antenna.

Fig. 7 is a flowchart illustrating a single carrier modulation method in fig. 6.

Referring to fig. 7, a scrambling unit 100 scrambles a TS to be transmitted (step 710).

The FEC unit 110 performs forward error correction on the scrambled TS from the scrambling unit 100 (step 720).

Meanwhile, the modulation information generating unit 145 generates modulation information regarding the modulation method of each region, which can be transmitted to the receiver through the frame synchronization region.

Subsequently, the MUX unit 120 receives the encoded TS, the segment sync information, the field sync information, and the generated modulation information, and thus inserts the segment sync information and/or the field sync information and the modulation information at a head position of the encoded TS according to a control signal to form a multiplexed TS including a frame sync area and a data area (step 730).

Subsequently, the pilot insertion unit 130 performs modulation on the frame synchronization region and the data region of the pilot-inserted TS output from the pilot insertion unit 130 using a corresponding modulation method (e.g., a single carrier modulation method) according to the modulation information in the pilot-inserted TS (step S750).

More specifically, in step S750, the area determination unit 141 determines the frame synchronization area and the data area of the transmission signal output from the pilot insertion unit 130 according to the control signal corresponding to the modulation information.

Finally, the radio frequency converter 150 performs conversion on the modulated TS from the modulation unit 143. (step S760).

For example, the frame sync region may be predetermined VSB modulation for transmission signals, and predetermined QAM modulation for modulation of the data region. In this case, the modulation unit 143 modulates the frame sync region according to VSB modulation, and modulates the data region according to QAM modulation. Further, the modulation unit 143 may use modulation of OQAM and QAM, VSB and OQAM, QAM and OQAM, OQAM and VSB, and QAM and VSB for the frame sync region and the data region, respectively. Preferably, the frequency of QAM sampling is half of OQAM, since QAM transmits data to both the I and Q components.

Fig. 8 shows an example of sample data according to single carrier modulation performed in the digital broadcast transmission system in fig. 6. Although this embodiment depicts two different modulations for the transmission signal in frame units, the data region applies to all three modulations.

According to the present invention, a single carrier transmission system can effectively cope with a variation in channel environment due to burst noise, and can also use a plurality of single carrier modulation methods. In particular, when OQAM and QAM, or VSB and QAM, are used, the clock of the frame synchronization region operates at twice the rate of the data region clock. Therefore, the receiver can improve the efficiency of reception by using an equalizer or the like. When VSB and OQAM are used, most of the signal distortion can be reduced compared to the conventional VSB modulation in a channel environment where burst noise exists in the in-phase component. Further, when OQAM and VSB modulation are used, most of signal distortion can be reduced compared to conventional OQAM in a channel environment in which short burst noise exists in an in-phase component.

Although the preferred embodiments of the present invention have been described, it will be understood by those skilled in the art that the present invention is not limited to the preferred embodiments but various changes and modifications may be made within the spirit and scope of the present invention as defined in the appended claims.

Claims (140)

1. A receiving system for receiving a signal including frame synchronization information, modulation information and payload data, comprising:

an A/D converter converting the received analog signal into digital data;

a modulation information extraction unit that extracts modulation information about a modulation method from the digital data;

a demodulation unit that demodulates a data area of the digital data using a demodulation method corresponding to the modulation information;

an FEC unit performing error correction decoding on the data region;

and a descrambling unit for descrambling the decoded data region to obtain data.

2. The receiving system of claim 1, wherein the demodulating unit further demodulates the frame synchronization region of the digital data using a demodulating method corresponding to the modulation information.

3. The receiving system of claim 1, further comprising:

and a pilot extraction unit for extracting a pilot from the demodulated data.

4. The receiving system of claim 1, wherein the frame synchronization information comprises segment synchronization information and/or field synchronization information.

5. The receiving system of claim 2, wherein the frame synchronization region includes a segment synchronization symbol, a field synchronization symbol, and a modulation information symbol in order, and the data region includes encoded data.

6. The receiving system of claim 2, wherein the frame synchronization region includes field synchronization symbols and modulation information symbols in order, and the data region includes encoded data.

7. The receiving system of claim 5 or 6, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to QAM demodulation.

8. The reception system according to claim 5 or 6, wherein the demodulation unit demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to QAM demodulation.

9. The receiving system of claim 5 or 6, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to OQAM demodulation.

10. The reception system according to claim 5 or 6, wherein the demodulation unit demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to OQAM demodulation.

11. The receiving system of claim 5 or 6, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to VSB demodulation.

12. The receiving system of claim 5 or 6, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to VSB demodulation.

13. The reception system according to claim 5 or 6, wherein the demodulation unit performs demodulation using the same sampling frequency for VSB demodulation and OQAM demodulation, and performs demodulation using a sampling frequency that is half of VSB demodulation and OQAM demodulation for QAM demodulation.

14. A receiving method for processing a signal including frame synchronization information, modulation information and payload data, comprising:

converting an analog signal received from the tuner into digital data;

extracting modulation information about a modulation method from the digital data;

demodulating a data region of the digital data using a demodulation method corresponding to the modulation information;

performing error correction decoding on the data region;

the decoded data region is descrambled to obtain data.

15. The receiving method as claimed in claim 14, wherein the demodulating step further demodulates the frame synchronization region of the digital data using a demodulating method corresponding to the modulation information.

16. The receiving method as claimed in claim 14, further comprising:

a pilot is extracted from the demodulated data.

17. The receiving method as claimed in claim 14, wherein the frame synchronization information comprises segment synchronization information and/or field synchronization information.

18. The receiving method as claimed in claim 15, wherein the frame synchronization region includes a segment synchronization symbol, a field synchronization symbol, and a modulation information symbol in order, and the data region includes encoded data.

19. The receiving method as claimed in claim 15, wherein the frame synchronization region includes field synchronization symbols and modulation information symbols in order, and the data region includes encoded data.

20. The receiving method as claimed in claim 18 or 19, wherein the demodulating step demodulates the frame sync region of the transmission signal according to VSB demodulation and demodulates the data region according to QAM demodulation.

21. The receiving method as claimed in claim 18 or 19, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to QAM demodulation.

22. The receiving method as claimed in claim 18 or 19, wherein the demodulating step demodulates the frame sync region of the transmission signal according to VSB demodulation and demodulates the data region according to OQAM demodulation.

23. The receiving method as claimed in claim 18 or 19, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to OQAM demodulation.

24. The receiving method as claimed in claim 18 or 19, wherein the demodulating step demodulates the frame sync region of the transmission signal according to OQAM demodulation and demodulates the data region according to VSB demodulation.

25. The receiving method as claimed in claim 18 or 19, wherein the demodulating step demodulates the frame sync region of the transmission signal according to QAM demodulation and demodulates the data region according to VSB demodulation.

26. The receiving method of claim 18 or 19, wherein the demodulating step performs demodulation using the same sampling frequency for VSB demodulation and OQAM demodulation, and performs demodulation using a sampling frequency half of VSB demodulation and OQAM demodulation for QAM demodulation.

27. A receiving system for receiving a signal including frame synchronization information, modulation information and payload data, comprising:

an A/D converter converting the received analog signal into digital data;

a modulation information extraction unit that extracts modulation information about a modulation method from the digital data;

a demodulation unit which demodulates a frame synchronization region and a data region of the digital data using at least one demodulation method, respectively;

an FEC unit performing error correction decoding on the data region;

and a descrambling unit for descrambling the decoded data region to obtain data.

28. The receiving system of claim 27, further comprising:

and a pilot extraction unit for extracting a pilot from the demodulated data.

29. The receiving system of claim 27, wherein the frame synchronization information comprises segment synchronization information and/or field synchronization information.

30. The receiving system of claim 27, wherein the frame synchronization region includes a segment synchronization symbol, a field synchronization symbol, and a modulation information symbol in order, and the data region includes encoded data.

31. The receiving system of claim 27, wherein the frame synchronization region includes field synchronization symbols and modulation information symbols in order, and the data region includes encoded data.

32. The receiving system of claim 27, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to QAM demodulation.

33. The reception system of claim 27, wherein the demodulation unit demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to QAM demodulation.

34. The reception system of claim 27, wherein the demodulation unit demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to OQAM demodulation.

35. The reception system of claim 27, wherein the demodulation unit demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to OQAM demodulation.

36. The reception system of claim 27, wherein the demodulation unit demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to VSB demodulation.

37. The reception system of claim 27, wherein the demodulation unit demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to VSB demodulation.

38. A receiving method for processing a signal including frame synchronization information, modulation information and payload data, comprising:

converting the received analog signal into digital data;

extracting modulation information about a modulation method from the digital data;

demodulating a frame synchronization region and a data region of the digital data using at least one demodulation method, respectively;

performing error correction decoding on the data region;

the decoded data region is descrambled to obtain data.

39. The receiving method as claimed in claim 38, further comprising:

a pilot is extracted from the demodulated data.

40. The receiving method as claimed in claim 38, wherein the frame synchronization information comprises segment synchronization information and/or field synchronization information.

41. The receiving method as claimed in claim 38, wherein the frame synchronization region includes a segment synchronization symbol, a field synchronization symbol, and a modulation information symbol in order, and the data region includes encoded data.

42. The receiving method as claimed in claim 38, wherein the frame synchronization region includes field synchronization symbols and modulation information symbols in order, and the data region includes encoded data.

43. The receiving method of claim 38, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to QAM demodulation.

44. The receiving method as claimed in claim 38, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to QAM demodulation.

45. The receiving method as claimed in claim 38, wherein the demodulating step demodulates the frame sync region of the transmission signal according to VSB demodulation and demodulates the data region according to OQAM demodulation.

46. The receiving method as claimed in claim 38, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to OQAM demodulation.

47. The receiving method as claimed in claim 38, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to VSB demodulation.

48. The receiving method as claimed in claim 38, wherein the demodulating step demodulates the frame sync region of the transmission signal according to QAM demodulation and demodulates the data region according to VSB demodulation.

49. A receiving system for receiving a broadcast signal including frame synchronization information, modulation information, and payload data, comprising:

a receiving unit receiving a signal having modulation information and converting the signal into digital data;

a demodulation unit that demodulates a data area of the digital data using a demodulation method corresponding to the modulation information;

and a decoding unit for decoding the demodulated digital data.

50. The receiving system of claim 49, wherein the demodulating unit further demodulates the frame synchronization region of the digital data using a demodulating method corresponding to the modulation information.

51. The receiving system of claim 49, further comprising:

and a pilot extraction unit for extracting a pilot from the demodulated data.

52. The receiving system of claim 49, wherein the frame synchronization information comprises segment synchronization information and/or field synchronization information.

53. The receiving system of claim 50, wherein the frame synchronization region includes a segment synchronization symbol, a field synchronization symbol, and a modulation information symbol in order, and the data region includes encoded data.

54. The receiving system of claim 50, wherein the frame synchronization region includes field synchronization symbols and modulation information symbols in order, and the data region includes encoded data.

55. The receiving system of claim 53 or 54, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to QAM demodulation.

56. The reception system of claim 53 or 54, wherein the demodulation unit demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to QAM demodulation.

57. The receiving system of claim 53 or 54, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to OQAM demodulation.

58. The reception system of claim 53 or 54, wherein the demodulation unit demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to OQAM demodulation.

59. The receiving system of claim 53 or 54, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to VSB demodulation.

60. The receiving system of claim 53 or 54, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to VSB demodulation.

61. The reception system according to claim 53 or 54, wherein the demodulation unit performs demodulation using the same sampling frequency for VSB demodulation and OQAM demodulation, and performs demodulation using a sampling frequency that is half of VSB demodulation and OQAM demodulation for QAM demodulation.

62. A receiving method for processing a broadcast signal including frame synchronization information, modulation information, and payload data transmitted from a transmission end, comprising:

receiving a signal having modulation information and converting the signal into digital data;

demodulating a data region of the digital data using a demodulation method corresponding to the modulation information;

the demodulated digital data is decoded.

63. The receiving method as claimed in claim 62, wherein the demodulating step further demodulates the frame synchronization region of the digital data using a demodulating method corresponding to the modulation information.

64. The receiving method of claim 62, further comprising:

a pilot is extracted from the demodulated data.

65. The receiving method as claimed in claim 62, wherein the frame synchronization information comprises segment synchronization information and/or field synchronization information.

66. The receiving method as claimed in claim 63, wherein the frame synchronization region includes a segment synchronization symbol, a field synchronization symbol, and a modulation information symbol in order, and the data region includes encoded data.

67. The receiving method as claimed in claim 63, wherein the frame synchronization region includes field synchronization symbols and modulation information symbols in order, and the data region includes encoded data.

68. The receiving method as claimed in claim 66 or 67, wherein the demodulating step demodulates the frame sync region of the transmission signal according to VSB demodulation and demodulates the data region according to QAM demodulation.

69. The receiving method as claimed in claim 66 or 67, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to QAM demodulation.

70. The receiving method as claimed in claim 66 or 67, wherein the demodulating step demodulates the frame sync region of the transmission signal according to VSB demodulation and demodulates the data region according to OQAM demodulation.

71. The receiving method as claimed in claim 66 or 67, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to OQAM demodulation.

72. The receiving method as claimed in claim 66 or 67, wherein the demodulating step demodulates the frame sync region of the transmission signal according to OQAM demodulation and demodulates the data region according to VSB demodulation.

73. The receiving method as claimed in claim 66 or 67, wherein the demodulating step demodulates the frame sync region of the transmission signal according to QAM demodulation and demodulates the data region according to VSB demodulation.

74. The receiving method of claim 66 or 67, wherein the demodulating step performs demodulation using the same sampling frequency for VSB demodulation and OQAM demodulation, and performs demodulation using a sampling frequency half of VSB demodulation and OQAM demodulation for QAM demodulation.

75. A reception system for receiving a broadcast signal including frame synchronization information, modulation information, and payload data transmitted from a transmission end, comprising:

a receiving unit receiving a signal having modulation information and converting the signal into digital data;

a demodulation unit which demodulates a frame synchronization region and a data region of the digital data using at least one demodulation method, respectively;

and a decoding unit for decoding the demodulated digital data.

76. The receiving system of claim 75, further comprising:

and a pilot extraction unit for extracting a pilot from the demodulated data.

77. The receiving system of claim 75, wherein the frame synchronization information comprises segment synchronization information and/or field synchronization information.

78. The receiving system of claim 75, wherein the frame synchronization region includes a segment synchronization symbol, a field synchronization symbol, and a modulation information symbol in order, and the data region includes encoded data.

79. The receiving system of claim 75, wherein the frame synchronization region includes field synchronization symbols and modulation information symbols in order, and the data region includes encoded data.

80. The receiving system of claim 75, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to QAM demodulation.

81. The reception system of claim 75, wherein the demodulation unit demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to QAM demodulation.

82. The receiving system of claim 75, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to OQAM demodulation.

83. The reception system of claim 75, wherein the demodulation unit demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to OQAM demodulation.

84. The receiving system of claim 75, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to VSB demodulation.

85. The receiving system of claim 75, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to VSB demodulation.

86. A receiving method for processing a broadcast signal including frame synchronization information, modulation information, and payload data transmitted from a transmission end, comprising:

receiving a signal having modulation information and converting the signal into digital data;

demodulating a frame synchronization region and a data region of the digital data using at least one demodulation method, respectively;

the demodulated digital data is decoded.

87. The receiving method of claim 86, further comprising:

a pilot is extracted from the demodulated data.

88. The receiving method as claimed in claim 86, wherein the frame synchronization information comprises segment synchronization information and/or field synchronization information.

89. The receiving method as claimed in claim 86, wherein the frame synchronization region includes a segment synchronization symbol, a field synchronization symbol, and a modulation information symbol in order, and the data region includes encoded data.

90. The receiving method as claimed in claim 86, wherein the frame synchronization region includes field synchronization symbols and modulation information symbols in order, and the data region includes encoded data.

91. The receiving method of claim 86, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to QAM demodulation.

92. The receiving method as claimed in claim 86, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to QAM demodulation.

93. The receiving method of claim 86, wherein the demodulating step demodulates the frame sync region of the transmission signal according to VSB demodulation and demodulates the data region according to OQAM demodulation.

94. The receiving method as claimed in claim 86, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to OQAM demodulation.

95. The receiving method of claim 86, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to VSB demodulation.

96. The receiving method of claim 86, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to VSB demodulation.

97. A receiving system for receiving a signal including frame synchronization information, modulation information and payload data, comprising:

an A/D converter converting the received analog signal into digital data;

a demodulation unit that demodulates the converted data;

an FEC unit performing error correction on the demodulated data;

a descrambling unit for descrambling the error-corrected data,

wherein the demodulation unit demodulates the data area of the digital data using a demodulation method corresponding to the modulation information.

98. The receiving system of claim 97, wherein the demodulating unit further demodulates the frame synchronization region of the digital data using a demodulating method corresponding to the modulation information.

99. The receiving system of claim 97, wherein the frame synchronization information comprises segment synchronization information and/or field synchronization information.

100. The receiving system of claim 98, wherein the frame synchronization region includes a segment synchronization symbol, a field synchronization symbol, and a modulation information symbol in order, and the data region includes encoded data.

101. The receiving system of claim 98, wherein the frame synchronization region includes field synchronization symbols and modulation information symbols in order, and the data region includes encoded data.

102. The receiving system of claim 100 or 101, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to QAM demodulation.

103. The reception system of claim 100 or 101, wherein the demodulation unit demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to QAM demodulation.

104. The receiving system of claim 100 or 101, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to OQAM demodulation.

105. The reception system of claim 100 or 101, wherein the demodulation unit demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to OQAM demodulation.

106. The receiving system of claim 100 or 101, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to VSB demodulation.

107. The receiving system of claim 100 or 101, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to VSB demodulation.

108. The reception system of claim 100 or 101, wherein the demodulation unit performs demodulation using the same sampling frequency for VSB demodulation and OQAM demodulation, and performs demodulation using a sampling frequency that is half of VSB demodulation and OQAM demodulation for QAM demodulation.

109. A receiving method for processing a signal including frame synchronization information, modulation information and payload data, comprising:

an a/D conversion step of converting the received analog signal into digital data;

a demodulation step of demodulating the converted data;

a decoding step of correcting errors of the demodulated data;

a descrambling step of descrambling the error-corrected data,

wherein the demodulating step demodulates the data area of the digital data using a demodulation method corresponding to the modulation information.

110. The receiving method of claim 109, wherein the demodulating step further demodulates the frame synchronization region of the digital data using a demodulating method corresponding to the modulation information.

111. The receiving method of claim 109, wherein the frame synchronization information comprises segment synchronization information and/or field synchronization information.

112. The receiving method as claimed in claim 110, wherein the frame synchronization region includes a segment synchronization symbol, a field synchronization symbol, and a modulation information symbol in order, and the data region includes encoded data.

113. The receiving method as claimed in claim 110, wherein the frame synchronization region includes field synchronization symbols and modulation information symbols in order, and the data region includes encoded data.

114. The receiving method as claimed in claim 112 or 113, wherein the demodulating step demodulates the frame sync region of the transmission signal according to VSB demodulation and demodulates the data region according to QAM demodulation.

115. The receiving method as claimed in claim 112 or 113, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to QAM demodulation.

116. The receiving method as claimed in claim 112 or 113, wherein the demodulating step demodulates the frame sync region of the transmission signal according to VSB demodulation and demodulates the data region according to OQAM demodulation.

117. The receiving method as claimed in claim 112 or 113, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to OQAM demodulation.

118. The receiving method as claimed in claim 112 or 113, wherein the demodulating step demodulates the frame sync region of the transmission signal according to OQAM demodulation and demodulates the data region according to VSB demodulation.

119. The receiving method as claimed in claim 112 or 113, wherein the demodulating step demodulates the frame sync region of the transmission signal according to QAM demodulation and demodulates the data region according to VSB demodulation.

120. The receiving method of claim 112 or 113, wherein the demodulating step performs demodulation using the same sampling frequency for VSB demodulation and OQAM demodulation, and performs demodulation using a sampling frequency half of VSB demodulation and OQAM demodulation for QAM demodulation.

121. A receiving system for receiving a signal including frame synchronization information, modulation information and payload data, comprising:

an A/D converter converting the received analog signal into digital data;

a demodulation unit that demodulates the converted data;

an FEC unit performing error correction on the demodulated data;

a descrambling unit for descrambling the error-corrected data,

wherein the demodulation unit demodulates a frame synchronization region and a data region of the digital data using at least one demodulation method, respectively.

122. The receiving system of claim 121, wherein the frame synchronization information comprises segment synchronization information and/or field synchronization information.

123. The receiving system of claim 121, wherein the frame synchronization region includes a segment synchronization symbol, a field synchronization symbol, and a modulation information symbol in order, and the data region includes encoded data.

124. The receiving system of claim 121, wherein the frame synchronization region includes field synchronization symbols and modulation information symbols in order, and the data region includes encoded data.

125. The receiving system of claim 121, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to QAM demodulation.

126. The receiving system of claim 121, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to QAM demodulation.

127. The receiving system of claim 121, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to VSB demodulation and demodulates the data region according to OQAM demodulation.

128. The receiving system of claim 121, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to OQAM demodulation.

129. The receiving system of claim 121, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to VSB demodulation.

130. The receiving system of claim 121, wherein the demodulating unit demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to VSB demodulation.

131. A receiving method for processing a signal including frame synchronization information, modulation information and payload data, comprising:

an a/D conversion step of converting the received analog signal into digital data;

a demodulation step of demodulating the converted data;

a decoding step of correcting errors of the demodulated data;

a descrambling step of descrambling the error-corrected data,

wherein the demodulating step demodulates the frame synchronization region and the data region of the digital data using at least one demodulation method, respectively.

132. The receiving method of claim 131, wherein the frame synchronization information comprises segment synchronization information and/or field synchronization information.

133. The receiving method as claimed in claim 131, wherein the frame synchronization region includes a segment synchronization symbol, a field synchronization symbol, and a modulation information symbol in order, and the data region includes encoded data.

134. The receiving method as claimed in claim 131, wherein the frame synchronization region includes field synchronization symbols and modulation information symbols in order, and the data region includes encoded data.

135. The receiving method of claim 131, wherein the demodulating step demodulates the frame sync region of the transmission signal according to VSB demodulation and demodulates the data region according to QAM demodulation.

136. The receiving method of claim 131, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to OQAM demodulation and demodulates the data region according to QAM demodulation.

137. The receiving method of claim 131, wherein the demodulating step demodulates the frame sync region of the transmission signal according to VSB demodulation and demodulates the data region according to OQAM demodulation.

138. The receiving method of claim 131, wherein the demodulating step demodulates the frame synchronization region of the transmission signal according to QAM demodulation and demodulates the data region according to OQAM demodulation.

139. The receiving method of claim 131, wherein the demodulating step demodulates the frame sync region of the transmission signal according to OQAM demodulation and demodulates the data region according to VSB demodulation.

140. The receiving method of claim 131, wherein the demodulating step demodulates the frame sync region of the transmission signal according to QAM demodulation and demodulates the data region according to VSB demodulation.