EP2100450A1

EP2100450A1 - Apparatus and method for digital multimedia broadcasting service

Info

Publication number: EP2100450A1
Application number: EP07851295A
Authority: EP
Inventors: Ju-Yeun Kim; Jae-Hwui Bae; So-Ra Park; Hyoungsoo Lim; Yang-Su Kim; Young-Su Kim; Seomee Choi; Jae-Hyun Seo; Heung-Mook Kim; Jong-Soo Lim; Soo-In Lee; Chieteuk Ahn; Nak-Woong Eum
Original assignee: Electronics and Telecommunications Research Institute ETRI
Current assignee: Electronics and Telecommunications Research Institute ETRI
Priority date: 2006-12-06
Filing date: 2007-12-06
Publication date: 2009-09-16
Also published as: CN101601290A; KR101314249B1; WO2008069600A1; CN101601290B; KR20080052459A; EP2100450A4

Abstract

Provided is an apparatus and method for a digital multimedia broadcasting (DMB) service. The DMB transmitter includes a base layer transmission processor for encoding base layer stream, an enhancement layer transmission processor for encoding enhancement layer stream, and a hierarchical transmitter for transmitting the base layer stream and the enhancement layer stream by allocating a predetermined bit value through encoding the base layer stream outputted from the base layer transmission processor and the enhancement layer stream outputted from the enhancement layer transmission processor based on gray coding and performing hierarchical symbol mapping.

Description

DESCRIPTION

APPARATUS AND METHOD FOR DIGITAL MULTIMEDIA BROADCASTING

SERVICE TECHNICAL FIELD The present invention relates to an apparatus and method for a digital multimedia broadcasting (DMB) service; and, more particularly, to an apparatus and method for providing DMB services with high quality and high transmission-efficiency while maintaining backward compatibility with typical DMB systems.

BACKGROUND ART

Fig. 1 illustrates a digital multimedia broadcasting (DMB) transmitter according to the related art. Referring to Fig. 1, the DMB transmitter according to the related art includes an MPEG-4 video encoder 101 and an MPEG-4 audio encoder 103 for encoding multimedia sources, an MPEG-4 system encoder 105 for objectivating and synchronizing media streams, an MPEG-2 transport stream (TS) multiplexer 107 for multiplexing a media stream, a Reed-Solomon (RS) encoder 109 for additional error control coding, a convolutional interleaver 111 for removing temporal correlation of adjacent unit bytes in a data stream, and a digital audio broadcasting (DAB) transmitter for converting a stream outputted from the convolutional interleaver 111 to a digital broadcasting signal and outputting the digital broadcasting signal.

The DAB transmitter 113 has a structure employing a DAB standard (ETSI EN 300 401 vl.4.1, June, 2006, Radio Broadcasting Systems; Digital Audio Broadcasting (DAB) to mobile, portable and fixed receivers) . Hereinafter, the DAB transmitter 113 will be described in detail.

Fig. 2 is a diagram illustrating the DAB transmitter of Fig. 1. That is, Fig. 2 shows a Eureka 147 DAB transmitter employing a DAB standard. Referring to Fig. 2, the DAB transmitter 113 includes an energy dispersal scrambler 201, a convolutional encoder 203, a time interleaver 205, a symbol mapper 207, a frequency interleaver 209, a differential modulator 211, a inverse fast Fourier transform (IFFT) 213, and a guard interval inserter 215.

The energy dispersal scrambler 201 disperses the energy of a stream outputted from the convolution interleaver 111 and the convolutional encoder 203 performs convolutional encoding on the stream at different coding rates according to unequal error protection (UEP) or equal error protection (EEP) . The stream outputted from the convolutional encoder 203 is formed of logical frames. The time interleaver 205 interleaves a predetermined tame in the stream outputted from the convolutional encoder 230 at every 16 logical unit frames. The interleaved data is multiplexed to form a common interleaved frame (FIC). Then, the symbol mapper 207 performs symbol-mapping by forming a synchronization channel for frames outputted from the time interleaver 205 and a fast information channel (FIC) and a main service channel for transmitting valid data and modulating the frame based on quadrature phase shift keying (QPSK) . Finally, a DAB transmit frame is formed in a 24ms of a unit length.

The frequency interleaver 209 performs frequency interleaving for a signal outputted from the symbol mapper 207. The differential modulator 211 modulates a QPSK-modulated stream outputted from the symbol mapper 207 based on ^T differential QPSK ( ^"Ur DQPSK) . The differential modulator 211 differentially modulates an output signal of the frequency interleaver 209 by an OFDM unit symbol based on a phase reference signal where OFDM stands for orthogonal frequency division multiplexing based on a phase reference signal. Then, the IFFT 213 performs zero-padding and inverse fast Fourier transform (IFFT) for an output signal of the differential modulator 211. The output signal of the

IFFT 213 is a time in a time domain. The guard interval inserter 215 removes inter-symbol interference (ISI) from the output signal of the IFFT 213 by inserting data

(guard interval) corresponding to about 1/4 of an end of a valid symbol interval at the front of a valid symbol.

The available transmit rate of the DMB transmitter according to the related art is about 1.152 Mbps if convolutional coding with 1/2 coding rate is used. That is, 576 kbps of a transmit rate is allocated to each service when two multimedia services are provided through one channel. Therefore, such related technology cannot provide high quality services although multimedia sources are encoded to have high quality because a corresponding transmit rate is not supported.

DISCLOSURE

TECHNICAL PROBLEM

An embodiment of the present invention is directed to providing an apparatus and method for providing a digital multimedia broadcasting (DMB) service with high quality and high transmission efficiency while sustaining backward compatibility with typical DMB system by transmitting multimedia data with a base layer and an enhancement layer divided.

Other objects and advantages of the present invention can be understood by the following description, and become apparent with reference to the embodiments of the present invention. Also, it is obvious to those skilled in the art of the present invention that the objects and advantages of the present invention can be realized by the means as claimed and combinations thereof. TECHNICAL SOLUTION

In accordance with an aspect of the present invention, there is provided a digital multimedia broadcasting (DMB) transmitter including: a base layer transmission processor for encoding base layer stream by encoding a base layer stream; an enhancement layer transmission processor for encoding enhancement layer stream by encoding an enhancement layer stream; and a hierarchical transmitter for encoding the base layer stream outputted from the base layer transmission processor the enhancement layer stream outputted from the enhancement layer transmission processor based on gray coding, allocating a predetermined bit value, performing hierarchical symbol mapping, and transmitting the base layer stream and the enhancement layer stream.

In accordance with another aspect of the present invention, there is provided a DMB receiver including: a hierarchical receiver for separating an encoded base layer stream and an encoded enhancement layer stream from a receiving signal by performing hierarchical symbol de- mapping on the receiving signal where a predetermined bit value is allocated to and hierarchical symbol is mapped to through encoding according to gray coding; a base layer receiving processor for decoding the encoded base layer stream; and an enhancement layer receiving processor for decoding the encoded enhancement layer stream.

ADVANTAGEOUS EFFECTS

According to the present invention, multimedia and supplementary data services can be provided with high quality and high transmission efficiency while sustaining backward compatibility with typical DMB systems. According to the present invention, high quality services can be provided by transmitting further more information than typical DMB systems through hierarchical modulation. Also, high transmission efficient service can be provided by securing further more channels.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 illustrates a digital multimedia broadcasting (DMB) transmitter according to the related art. Fig. 2 shows a DAB transmitter of Fig. 1.

Fig. 3 illustrates a transmitter in accordance with an embodiment of the present invention.

Fig. 4 illustrates the base layer transmission processor of Fig. 3. Fig. 5 illustrates an enhancement layer transmission processor of Fig. 3.

Fig. 6 illustrates a hierarchical DAB transmitter of Fig. 3.

Fig. 7 is a constellation of -4 DQPSK modulated base layer stream symbol.

Figs. 8 and 9 show examples of hierarchical symbol mapping in accordance with an embodiment of the present invention.

Figs. 10 and 11 are examples of hierarchical symbol mapping according to an embodiment of the present invention .

Fig. 12 is a diagram illustrating a transmitter in accordance with an embodiment of the present invention.

Fig. 13 illustrates a receiver in accordance with an embodiment of the present invention.

Fig. 14 illustrates a DAB receiver of Fig. 13. Fig. 15 illustrates a receiving method in accordance with an embodiment of the present invention.

Fig. 16 illustrates a receiver in accordance with an embodiment of the present invention. Fig. 17 illustrates a transmitter in accordance with an embodiment of the present invention.

Fig. 18 illustrates an enhancement layer transmission processor of Fig. 17. Fig. 19 illustrates a hierarchical DMB transmitter of Fig. 17.

Fig. 20 illustrates a hierarchical DMB transmitter of Fig. 17.

Fig. 21 illustrates a receiver in accordance with an embodiment of the present invention.

Fig. 22 illustrates a hierarchical DMB receiver of Fig. 21.

Fig. 23 illustrates a hierarchical DMB receiver of Fig. 21. Fig. 24 illustrates an enhancement layer receiving processor of Fig. 21.

Fig. 25 is constellation of Null signal of a base layer stream.

Fig. 26 is constellation of a phase reference signal of a base layer stream.

Fig. 27 is constellation showing hierarchical symbol mapping performed by a hierarchical symbol mapper when a differential modulator modulates a base layer stream signal based on ^ DQPSK in accordance with an embodiment of the present invention, where a hierarchical symbol mapper maps symbols of an enhancement layer stream signal for (2n+l)^th symbols.

Fig. 28 is constellation describing hierarchical symbol mapping performed by a hierarchical symbol mapper when a differential modulator modulates a base layers

TV stream based on a ^"-*^" DQPSK scheme in accordance with an embodiment of the present invention, where a hierarchical symbol mapper maps symbols of an enhancement layer stream signal for (2n)^th symbols. Fig. 29 is constellation showing hierarchical symbol mapping performed by a hierarchical symbol mapper when a differential modulator modulates a base layers stream based on a ^~^ DQPSK scheme Ln accordance with another embodiment of the present invention, where a hierarchical symbol mapper maps symbols of an enhancement layer stream signal for (2n+l)^th symbols.

Fig. 30 is constellation showing hierarchical symbol mapping performed by a hierarchical symbol mapper when a differential modulator modulates a base layers stream based on a -4 DQPSK scheme in accordance with another embodiment of the present invention, where a hierarchical symbol mapper maps symbols of an enhancement layer stream signal for (2n)^th symbols.

Fig. 31 is constellation showing hierarchical symbol mapping performed by a hierarchical symbol mapper when a differential modulator modulates a base layers stream based on a -* DQPSK scheme Ln accordance with another embodiment of the present invention, where a hierarchical symbol mapper maps symbols of an enhancement layer stream signal for (2n+l)^th symbols.

Fig. 32 is constellation showing hierarchical symbol mapping performed by a hierarchical symbol mapper when a differential modulator modulates a base layers stream based on a -4- DQPSK scheme Ln accordance with another embodiment of the present invention, where a hierarchical symbol mapper maps symbols of an enhancement layer stream signal for (2n)^th symbols.

Fig. 33 illustrates a transmitter in accordance with an embodiment of the present invention. Fig. 34 illustrates an enhancement layer transmission processor of Fig. 33.

Fig. 35 illustrates a receiver in accordance with an embodiment of the present invention.

Fig. 36 illustrates an enhancement layer receiving processor of Fig. 35. BEST MODE FOR THE INVENTION

The advantages, features and aspects of the invention will become apparent from the following description of the embodiments with reference to the accompanying drawings, which is set forth hereinafter. Therefore, those skilled in the field of this art of the present invention can embody the technological concept and scope of the invention easily. Also, all of conditional terms and embodiments in the specification are fundamentally used in a purpose of disclosing the concept of the prevent invention. Thus, the present inventions are not limited by thereof.

Also, all detail descriptions for a specific embodiment as well as fundamentals, aspects, and embodiments of the present invention must be understood as that the detail descriptions include structural and functional equivalents thereof . Such structural and functional equivalents must be understood as known equivalents, equivalents that will be developed in future, and all elements invented to perform the same function regardless of structures thereof.

Therefore, for example, block diagrams of the specification must be understood in a conceptual view point of exemplary circuits that embody the fundamentals of the present invention. Similarly, all flowcharts, state diagrams, and pseudo-codes may be substantially presented at a computer readable medium and represent various processes that may be performed by a computer or a processor regardless of whether a computer or a processor is clearly shown or not.

Functions of various elements in diagrams, such as functional blocks shown as processors or equivalents, may be provided using hardware capable of executing predetermined software or related software as well as dedicated hardware. When it is provided using processors, the functions may be provided by a single dedicated processor, a single shared processor, or a plurality of individual processors where one of the individual processor may be shared.

Also, terms 'processor' , ^Λcontrol' , or similar concepts must not be understood by exclusively citing hardware having capability of executing software. The terms must be understood as digital signal processor (DSP) hardware, and RAM, ROM, and nonvolatile memory for storing software without limitations.

The advantages, features and aspects of the invention will become apparent from the following description of the embodiments with reference to the accompanying drawings, which is set forth hereinafter. Like reference numerals designate like elements throughout the specification and drawings. In addition, if it is considered that detailed description on a related art may obscure the points of the present invention, the detailed description will not be provided herein. The preferred embodiments of the present invention will be described in detail hereinafter with reference to the attached drawings.

Referring to Fig. 3, the transmitter according to the present embodiment includes a scalable video encoder 301, a scalable audio encoder 303, an enhancement layer transmission processor 305, a base layer transmission processor 307, and a hierarchical digital audio broadcasting (DAB) transmitter 309.

The scalable video encoder 301 transforms video sources to an enhancement layer video stream having enhanced quality and a base layer video stream compatible with typical DMB systems. Then, the scalable video encoder 301 outputs the enhancement layer video stream to the enhancement layer transmission processor 307 and the base layer video stream to the base layer transmission processor 305. Similarly, the scalable audio encoder 303 transforms audio sources to an enhancement layer audio stream having enhanced quality and a base layer audio stream compatible with conventional DMB systems. Then, the scalable audio encoder 303 outputs the enhancement layer audio stream to the enhancement layer transmission processor 307 and the base layer audio stream to the; base layer transmission processor 305.

For example, the scalable video encoder 301 and the scalable audio encoder 303 may be an MPEG-4 scalable video encoder and an MPEG-4 scalable audio encoder. The enhancement layer video stream and the enhancement layer audio stream may be generated through well-known various scalable schemes.

Fig. 4 is a diagram illustrating the base layer transmission processor of Fig. 3.

The base layer transmission processor 307 processes base layer video and audio streams which support typical DMB systems. As shown in Fig. 4, the base layer transmission processor 307 includes a system encoder 401, a transmit stream (TS) multiplexer 403, a Reed-Solomon (RS) encoder 109, and a convolutional interleaver 111. For example, the system encoder 401 and the transmit stream multiplexer 403 may correspond to an MPEG-4 system encoder 109 and an MPEG-2 TS multiplexer 107, which are shown in Fig. 1. The RS encoder 109 and the convolution interleaver 111 were already shown in Fig. 1.

The system encoder 401 objectivates and synchronizes base layer multimedia streams outputted from the scalable video encoder 301 and the scalable audio encoder 303. The TS multiplexer 403 multiplexes an output signal of the system encoder 401 to a base layer stream. The RS encoder 109 performs error control coding on an output signal of the TS multiplexer 403. The convolutional interleaver 111 removes temporal correlation of adjacent byte-units in a stream from the output signal of the RF encoder 109 and outputs the temporal correlation-removed signal to the hierarchical DAB transmitter 309.

Fig. 5 is a diagram illustrating an enhancement layer transmission processor of Fig. 3. The enhancement layer transmission processor 305 processes an enhancement layer video stream and an enhancement layer audio stream to provide multimedia with higher quality than a base layer. As shown in Fig. 5, the enhancement layer transmission processor includes a system encoder 401, a transmit stream (TS) multiplexer 403, an energy dispersal scrambler 301, a channel encoder 501, and a time interleaver 205. For example, the system encoder 401 and the TS multiplexer 403 may correspond to an MPEG-4 system encoder 105 and an MPEG-2 TS multiplexer 107 shown in Fig. 1.

The system encoder 401 objectivates and synchronizes an enhancement layer video stream and an enhancement layer audio stream outputted from the scalable video encoder 301 and the scalable audio encoder 303. The transmit stream multiplexer 403 multiplexes an output signal of the system encoder 4OL to the enhancement layer stream. The energy dispersal scrambler 301, as shown in Fig. 2, disperse the energy of the enhancement layer stream outputted from the transmit stream multiplexer 403. The channel encoder 501 performs channel-coding on an enhancement layer stream outputted from the energy dispersal scrambler 201. The channel-coded signal has a strong error correction function in a radio transmit channel. Here, the channel coding may be archived by one of Reed-Solomon (RS) encoding, convolution encoding, low density parity check (LDPC) encoding, turbo encoding, Bose-Chaudhuri-Hocquenghen (BCH) encoding, and concatenated encoding thereof. A channel coding rate may be changed by a rate compatible punctured code (RCPC) . The time interleaver 205 performs temporal interleaving on the stream outputted from the channel encoder 501.

Fig. 6 illustrates a hierarchical DAB transmitter of Fig. 3.

The hierarchical DAB transmitter 309 further includes a hierarchical symbol mapper 601 as well as the constituent elements of the DAB transmitter 113. The hierarchical symbol mapper 601 maps an enhancement layer stream based on a modulated base layer stream signal. As shown in Fig. 6, the hierarchical DAB transmitter 309 includes an energy dispersal scrambler 201, a convolutional encoder 203, a time interleaver 205, a symbol mapper 207, a frequency interleaver 209, a differential modulator 211, an IFFT 213, and a guard interval inserter 215. Each oE the constituent elements corresponds to those shown in E'ig. 2. The symbol mapper 207 encodes an input stream based on QPSK according to gray coding.

The hierarchical symbol mapper 601 performs hierarchical symbol mapping on the enhancement layer stream outputted from the enhancement layer transmission processor 305 based on the differential modulated base layer stream signal from the differential modulator 211.

Hereinafter, hierarchical symbol mapping according to the present embodiment will be described in detail. The symbol mapper 207 allocates a 2-bit value by modulating a base layer stream based on QPSK, and the differential modulator 211 modulates the QPSK-modulated base layer stream based on -S DQPSK. Four quadrant lines denote a real number axis and an imaginary number axis, which are shifted as much as a ^ phase at a complex plane .

The hierarch symbol mapper 601 maps an enhancement layer stream symbol to the DQPSK modulated base layer stream. The hierarchical symbol mapper 601 may allocate supplementary information bits by modulating the enhancement layer stream based on one of 2-amplitude shift keying (2-ASK) , QPSK, and 16 quadrature amplitude modulation (16-QAM) . For example, the number of supplementary information bits may be 1-bit for 2-ASK, 2- bits for QPSK, and 4-bits for 16-QAM. Therefore, a transmit rate is additionally secured by transmitting addition bits.

Hereinafter, the hierarchical symbol mapping according to the present embodiment will be described in more detail.

An output of the differential modulator 211 for the 1^st symbol of a frequency-interleaved base layer stream from the frequency interleaver 209 to the k^th QPSK symbol is defined as Eq. 1.

In Eq. 1, 'Lk denotes the 1^th symbol of the frequency-interleaved base layer stream from the frequency interleaver 209 to the k^th QPSK symbol, L denotes the total number of base stream symbols, and K is the total number of multiple carriers.

Eq. 1 means that a base layer stream signal is modulated based on DQPSK. becomes one of values and _ Here, the size of the modulated symbol is assum s 1.

Fig. 7 is a constellation of a DQPSK modulated base layer stream symbol. That is, Fig. 7 is a constellation of the output of the differential modulator 211.

Meanwhile, when the base layer stream signal is

71 z modulated based on ^- DQPSK, the output '.* of the hierarchical symbol mapper 601 for the 1^th symbol of an enhancement layer stream outputted from the enhancement llaayyeerr ttrraannssmmiissssiioonn pprroocceess,sor 305 to the k^th carrier symbol is defined as Eq. 2.

In Eq. 2, ^zι« denotes the 1^th symbol of an enhancement layer stream to a symbol for the k^th subcarrier. ^'*'is a hierarchical symbol mapping function, which is determined according to the number of supplementary information bits of an enhancement layer and a modulation scheme.

As an example of the hierarchical symbol mapping function, the hierarchical symbol mapper 601 calculates ^zι.κ using Eq. 3 in case of 2-ASK where 1-bit of supplementary information bits is allocated to an enhancement layer stream.

In Eq. 3, a is constant larger than 0.

Figs. 8 and 9 show examples of hierarchical symbol mapping in accordance with an embodiment of the present invention. Figs. 8 and 9 show constellations of an enhancement layer stream signal hierarchically mapped based on 2-ASK with 1 bit of supplementary information bits when a base layer stream signal is modulated based on -* DQPSK. In Fig. white constellation denotes a symbol of a base layer stream, which is the output ^z/,_* of the differential modulator 211. A black constellation denotes the output of the hierarchical symbol mapper 601.

^~JT^~

If a base layer stream is modulated based on -4 DQPSK, the supplementary information bit for an enhancement layer stream is 2-bits, and Table 1 shows a hierarchical symbol mapping function for mapping symbols based on QPSK, as another example of a hierarchical symbol mapping function.

Table 1

In Table 1, A is information bit corresponding to ^zι,k , B is information bit corresponding to ^z/,* , and a is a constant larger than 0.

Figs. 10 and 11 are examples of hierarchical symbol mapping according to an embodiment of the present invention. That is, Figs. 10 and 11 show constellations of a symbol-mapped enhancement layer stream signal by Table 1. In Fig. 9, a white constellation denotes a symbol of a base layer stream, which is the output ^zι _* of the differential modulator 211, and a block constellation denotes the output ^z'.* of the hierarchical symbol mapper 601.

The enhancement layer may be used for providing a supplementary data service as well as providing a high quality service as described above. That is, the supplementary data source encoder 1007 is further included for providing a supplementary data service such as a supplementary multimedia service as shown in Fig. 12. That is, a supplementary data service can be provided by transmitting supplementary data through an enhancement layer stream. The supplementary video service may be a service related to base layer data such as stereo video and multi-view video or an independent additional service,

Hereinafter, the difference between the transmitters shown in Figs. 3 and 12 will be described. The scalable video encoder 301 and the scalable audio encoder 303 are replaced with a video encoder 1001 and an audio encoder 1003. The output signals of the video encoder 1001 and the audio encoder 1003 are input to the base layer transmission processor 307. ALso, a supplementary data source encoder 1007 is additionally included. The output signal of the supplementary data source encoder 1007 is input to the enhancement layer transmission processor 3005. The video encoder 1001 and the audio encoder 1003 may be an MPEG-4 video encoder 101 and an MPEG-4 audio encoder 103 shown in Fig. 1.

The transmitter of Fig. 12 can support not only services that are cooperated with various services supported by typical DMB systems but also supplementary data services which are independently added. Fig. 13 is a diagram illustrating a receiver in accordance with an embodiment of the present invention.

Referring to Fig. 13, the receiver according to the present embodiment includes a hierarchical DAB receiver 1101, a base layer receiving processor 1103, an enhancement layer receiving processor 1105, a scalable video decoder 1107, and a scalable audio decoder 1109.

The hierarchical DAB receiver 1001 removes a guard interval from a receiving signal and performs FFT and differential demodulation. The hierarchical DAB receiver 1101 perform frequency-deinterleaving on the differential-demodulated receiving signal and outputs the deinterleaved signal to the enhancement layer receiving processor 1105 and the base layer receiving processor 1103.

The base layer receiving processor 1103 includes a convolutional deinterleaver 1123, a RF decoder 1125, a transmit stream (TS) demultiplexer 1127, and a system decoder 1129. The base layer receiving processor 1103 processes a base layer stream which is transmitted from the transmitters shown in Figs. 1 and 2 or the transmitters according to the embodiments of the present invention, shown in Figs. 3 and 12. Therefore, the base layer receiving processor 1103 performs decoding corresponding to an encoding scheme performed for a base layer stream in the transmitters of Figs. 3 and 12. The convolutional interleaver 1123 and the RS decoder 1125 perform channel decoding. The convolutional deinterleaver 1123 performs convolutional deinterleaving on a base layer stream which is an output signal of the hierarchical DAB receiver 1101. The RS decoder 1125 performs additional error control decoding on the output signal of the convolutional de Lnterleaver 1123. The TS demultiplexer 1127 demultiplexes the output signal of the RS decoder 1125 to a multimedia and various supplementary information packets. The system decoder 1129 depacketizes the output signal of the TS demultiplexer 1127 and synchronizes streams and outputs the demultiplexed signal to the scalable video decoder 1107 and the scalable audio decoder 1109. For example, the system decoder 1129 may be an MPEG-4 system decoder.

The enhancement layer receiving processor 1105 includes a hierarchical symbol demapper 1111, a time deinterleaver 1113, a channel decoder 1115, an energy dispersal descrambler 1117, a transmit stream (TS) demultiplexer 1119, and a system decoder 1121. The enhancement layer receiving processor 1105 processes an enhancement layer stream transmitted from a transmitter according to the present embodiments such as the transmitters of Figs. 3 and 12. Therefore, the enhancement layer receiving processor 1105 performs a decoding operation corresponding to an encoding scheme used to encode the enhancement layer stream at the transmitter. A receiving signal includes hierarchical modulation information, for example, information about modulation schemes and supplementary information bits for the enhancement layer stream. The hierarchical symbol demapper 1111 separates the enhancement layer stream from an output signal of the hierarchical DAB receiver 1101 based on the hierarchical modulation information included in the receiving signal. The hierarchical symbol demapper 1111 performs demapping by performing decision to detect a base layer signal from the output signal of the hierarchical DAB receiver 1101 and separating an enhancement layer stream from the output signal from the hierarchical DAB receiver 1101 through calculating difference between the detected base layer signal and the receiving signal.

The time deinterleaver 1113, the channel decoder 1115, and the energy dispersal descrambler 1117 performs channel decoding.

The time deinterleaver 1113 deinterleaves the output signal of the hierarchical symbol demapper 1111. The channel decoder 1115 performs channel decoding for error correction of an output signal of the time interleaver 1113. The energy dispersal descrambler 1117 rearranges a signal scrambled for energy dispersion by descrambling an output signal of the channel decoder 1115. The TS demultiplexer 1119 demultiplexes the output signal of the energy dispersal descrambler 1117 to multimedia and various supplementary information packets. The system decoder 1121 depacketizes the output signal of the TS demultiplexer 1119 and synchronizes streams. Then, the system decoder 1121 outputs the depacketized and synchronized signal to the scalable video decoder 1107 and the scalable audio decoder 1109. The system decoder 1121 may be an MPEG-4 system decoder.

The scalable video decoder 1107 and the scalable audio decoder 1109 correspond to the scalable video encoder 301 and the scalable audio encoder 303 of Fig. 3. The scalable video decoder 1107 and the scalable audio decoder 1109 decode multimedia signal. The scalable video decoder 1107 and the scalable audio decoder 1109 perform scalable decoding on a base layer multimedia stream and an enhancement layer multimedia stream, thereby outputting high quality multimedia.

The receiver according to the present embodiment considers a stream transmitted from a conventional transmitter shown in Fig. 1 as a base layer stream and outputs basic quality multimedia.

Fig. 14 is a diagram illustrating a DAB receiver of Fig. 13.

The hierarchical DAB receiver 1101 has a structure corresponding to the hierarchical DAB transmitter 309 of Fig. 6, which is similar to a DAB receiving apparatus employing a DAB standard (ETSI EN 300 401 vl.4.1, June, 2006, Radio Broadcasting Systems; Digital Audio Broadcasting (DAB) to mobile, portable and fixed receivers ) . As shown in Fig. 14, the hierarchical DAB receiver 1101 includes a guard interval remover 1201, a FFT 1203, a differential demodulator 1205, a frequency deinterleaver 1207, a symbol demapper 1209, a time deinterleaver 1211, a convolutional decoder 1213, and an energy dispersal descrambler 1215.

The hierarchical DAB receiver 1101 performs inverse operations corresponding to those of the hierarchical DAB transmitter 309 of Fig. 6.

The guard interval remover 1201 removes a guard interval from a receiving signal. The FFT 1203 performs FFT on an output signal of the guard interval remover 1201. The differential demodulator 1205 demodulates an output signal of the FFT 1203 based on ^~^ DQPSK. An output signal of the differential demodulator 1205 is a base layer stream signal. The frequency deinterleaver 1207 deinterleaves the output signal of the differential demodulator 1205 in a frequency domain and outputs the deinterleaved signal to the enhancement layer receiving processor 1105 and the symbol demapper 1209. The symbol

7T demapper 1209 performs symbol demapping on the ^ DQPSK modulated base layer stream based on QPSK. The time deinterleaver 1211, the convolutional decoder 1213, and the energy dispersal descrambler 1215 perform channel decoding. The time deinterleaver 1211 deinterleaves the output signal of the symbol demapper 1209. The convolutional decoder 1213 performs convolutional decoding on the output signal of the time deinterleaver 1211. The energy dispersal descrambler 1215 rearranges a signal scrambled for energy dispersion by descrambling an output signal of the convolutional decoder 1213. Then, the energy dispersal descrambler 1215 outputs the rearranged scrambled signal to the base layer receiving processor 1103.

Fig. 15 is a flowchart illustrating a receiving method in accordance with an embodiment of the present invention .

At first, when a DMB service signal is received at step SIlO, information about multiplexing and services, which are included in a FIC of a TS frame, are detected at step S120. At step S130, broadcasting channel information is determined by extracting information related to a broadcasting channel, multiplexing, and services. If the broadcasting stream is a high quality and high transmission efficient DMB stream formed of a base layer stream and an enhancement layer stream at step S130, the receiving signal is separated to the base layer stream and the enhancement layer stream and channel decoding and media decoding are individually performed for the base and enhancement layer streams at step S151 and S152, thereby providing the high quality and high transmission efficient service at step S153. If the broadcasting stream is a DMB stream formed only of a typical broadcasting stream, channel decoding and media decoding are performed at steps S141 and S142 by extracting a base layer stream from the receiving signal, thereby providing a basic quality service at step S143.

Fig. 16 is a diagram illustrating a receiver in accordance with an embodiment of the present invention. The receiver of Fig. 16 has a structure corresponding to that of the transmitter of Fig. 12.

As shown in Fig. 16, the DMB receiver for a supplementary data service according the present embodiment includes a hierarchical DAB receiver 1101, a base layer receiving processor 1103, an enhancement layer receiving processor 1105, a video decoder 410, an audio decoder 420, and a supplementary a supplementary data decoder 430.

The hierarchical DAB receiver 1101, the base layer receiving processor 1103, the enhancement layer receiving processor 1105 have the same structures of those included in the receiver of Fig. 13. However, the enhancement layer receiving processor 1105 separates an enhancement layer stream for supplementary data from an output signal of the hierarchical DAB receiver 1101 and outputs the supplementary data. Also, the TS demultiplexer 1119 and the system decoder 1121 may be omitted according to the type of the supplementary data.

The video decoder 410 and the audio decoder 420 have structures corresponding to those of the video decoder 111 and the audio encoder 133 and decode a multimedia signal .

The supplementary data decoder 330 receives the supplementary data from the enhancement layer receiving processor 1105 and decodes the supplementary data according to a type thereof.

Fig. 17 is a diagram illustrating a transmitter in accordance with an embodiment of the present invention.

The DMB service using a base layer stream and an enhancement layer stream may allow broadcast multimedia through an enhancement layer stream, independently from multimedia broadcasted through a base layer stream. Therefore, a high transmission efficient broadcasting system may be provided according to the present invention as well as providing a high quality service. The transmitter of Fig. 17 is different from the transmitter of Fig. 13 as follows. The scalable video encoder 301 and the scalable audio encoder 303 are replaced with a video encoder 1501 and an audio encoder 1503 for encoding a multimedia source to be transmitted through an enhancement layer stream and a video encoder 1501 and an audio decoder 1507 for encoding multimedia source to be transmitted through a base layer stream. Therefore, the output signals of the video encoder 1501 and the audio encoder 1504 are input to the enhancement layer transmission processor 1509, and output signals of the video encoder 1505 and the audio encoder 1507 are input to the base layer transmission processor 307. The output signals of the enhancement layer transmission processor 1509 and the base layer transmission processor are input to the hierarchical DMB transmitter 1511. For example, the video encoders 1501 and 1505 and the audio encoders 1503 and 1507 may be an MPEG-4 video encoder 101 and an MPEG-4 audio encoder 103 of Fig. 1. The base layer transmission processor 307 of Fig. 3 is identical to the base layer transmission processor 307 of Fig. 17. The enhancement layer receiving processor 1509 will be described with reference to Fig. 18 in later. The detail structure of the hierarchical DMB transmitter 1511 will be described with reference to Figs. 19 and 20 in later. Fig. 18 is a diagram illustrating an enhancement layer transmission processor of Fig. 17.

As shown in Fig. 18, the enhancement layer transmission processor 1509 includes a system encoder 401, a transmit stream (TS) multiplexer 403, an external encoder 1601, and a convolutional interleaver 111. The system encoder 401 and the TS multiplexer 403 are identical to the system encoder 401 and the TS multiplexer 403 included in the enhancement layer transmission processor 305 of Fig. 5. The enhancement layer transmission processor 1509 of Fig. 18 uses the external encoder 1601 and the convolutional interleaver 111 unlike the enhancement layer transmission processor 305 of Fig. 5. It is because the hierarchical DMB transmitter 1511 includes an energy dispersal scrambler 201 for an enhancement layer stream as shown in Fig. 19.

The external encoder 611 performs channel encoding on an enhancement layer stream outputted from the TS multiplexer 403. The channel-encoded signal has a strong error control function at a radio transmission channel. Here, the channel encoding may be archived using one of RS encoding, convolutional encoding, low density parity check (LDPC) encoding, turbo encoding, Bose-Chaudhuri- Hocquenghen (BCH) encoding, and concatenated encoding thereof. The channel cording rate may vary according to a rate compatible punctured code (RCPC) . The convolutional interleaver 111 has the same structure of the convolutional interleaver 111 of Fig. 4 and removes temporal correlation of adjacent byte-units in a data stream.

Fig. 19 is a diagram illustrating a hierarchical DMB transmitter of Fig. 17.

As shown in Fig. 19, the hierarchical DMB transmitter 1511 includes an energy dispersal scrambler 201, a convolutional encoder 203, a time interleaver 205, a symbol mapper 207, a frequency interleaver 209, a differential modulator 211, an IFFT 213, and a guard interval inserter 215, which are included in the hierarchical DAB transmitter 309 of Fig. 6. The hierarchical DMB transmitter 1511 performs the operation of processing a base layer stream, which was described with reference to Fig. 6.

Unlike the hierarchical DMB transmitter 309 of Fig. 6, the energy dispersal scrambler 201, the internal encoder 621, the time interleaver 205, the symbol mapper 207, and the frequency interleaver 209 of the hierarchical DMB transmitter 1511 of Fig. 19 process an enhancement layer stream. The enhancement layer stream outputted from the frequency interleaver 209 has tenacity against error. Here, the internal encoder 1701 performs internal encoding on the enhancement layer stream unlike the convolutional encoder 203 that performs convolutional encoding on the base layer stream. As the internal encoder, a turbo encoder, a LDPC encoder, or a convolutional encoder may be used, and it may be decided by the concatenation performance of the external encoder 1601 shown in Fig. 18.

The enhancement layer stream outputted from the frequency interleaver 209 and the base layer stream outputted from the differential demodulator 211 are input to the hierarchical symbol mapper 601. The hierarchical symbol mapper 601 performs hierarchical symbol mapping on the enhancement layer stream outputted from the enhancement layer transmission processor 1509 based on the 4 DQPSK modulated base layer stream signal. The operations of the hierarchical symbol mapper 601 will be described with reference to Figs. 27 to 32.

Fig. 20 is a diagram illustrating a hierarchical DMB transmitter of Fig. 17. Differences between the hierarchical DMB transmitters shown in Figs. 19 and 20 are as follows. The hierarchical symbol mapper 601 hierarchically maps symbols of an enhancement layer stream and a base layer stream outputted from the symbol mapper 207, the frequency interleaver 209 performs frequency interleaving, and the differential modulator 211 performs differential modulations. The differential modulated signal is input to the IFFT 213. That is, it is not necessary to include a frequency interleaver that performs frequency interleaving on an enhancement layer stream which is not hierarchical symbol mapped.

Fig. 21 is a diagram illustrating a receiver in accordance with an embodiment of the present invention. The receiver of Fig. 21 has a structure corresponding to that of the transmitter of Fig. 17. As shown in Fig. 21, the receiver according to the present embodiment includes a hierarchical DMB receiver 1901, a base layer receiving processor 1103, an enhancement layer receiving processor 1903, video decoders 1905 and 1909, and audio decoders 1907 and 1911. The video decoders 1905 and J 909 and the audio decoders 1907 and 1911 may be an MPEG-4 video decoder and an MPEG- 4 audio decoder. The video decoder 1909 and the audio decoder 1911 decode a multimedia signal outputted from the base layer receiving processor 1103, and the video decoder 1905 and the audio decoder 1907 decodes a multimedia signal independent from multimedia of a base layer stream, as a multimedia signal outputted from the enhancement layer receiving processor 1903. The base layer receiving processor 1103 is identical to the base layer receiving processor 1103 included in the receiver of Fig. 13. The enhancement layer receiving processor 1903 will be described with reference to Fig. 24. The detail structure of the hierarchical DMB receiver 1901 will be described with reference to F¹IgS. 22 and 23.

Fig. 22 is a diagram illustrating a hierarchical DMB receiver of Fig. 21.

As shown in Fig. 22, the hierarchical DMB receiver 1901 includes a guard interval remover 1201, a FFT 1203, a differential demodulator 1205, a hierarchical symbol demapper 2001, a frequency deinterleaver 1207, a symbol demapper 1209, a time deinterleaver 1211, an internal decoder 2003, a convolutional decoder 1213, and an energy dispersal descrambler 1215.

The hierarchical DMB receiver 1901 performs inverse operations corresponding to those of the hierarchical DMB transmitter 1511 of Fig. 19. The guard interval remover 1201 removes a guard interval from a receiving signal. The FFT 1203 performs FFT on the output signal of the guard interval remover 1201. The output signal of the FFT 1203 is a signal generated by hierarchically mapping the symbols of the enhancement layer signal to the base layer stream. The output signal of the FFT 1203 is a hierarchical symbol mapped signal like constellations shown in Figs. 27 and 32. The hierarchical symbol demapper 2001 separates an enhancement layer stream from the output signal from the FFT 1203. A receiving signal includes hierarchical modulation information, for example, information about modulation for enhancement layer stream and supplementary information bits. The hierarchical symbol demapper 2001 separates an enhancement layer stream from the output signal of the FFT 1203 based on the hierarchical modulation information included in the receiving signal. The hierarchical symbol demapper 2001 performs decision to detect a base layer signal based on the output signal of the FFT 1203 and separates an enhancement layer stream by calculating the detected base layer signal and the receiving signal, thereby performing de-mapping. The differential demodulator 1205 demodulates the output signal of the FFT 1203 based on DQPSK. The output signal of the differential demodulator 1205 is a base layer stream signal. The base layer stream and the enhancement layer stream are input to the frequency deinterleaver 1207. The frequency deinterleaver 1207 deinterleaves the output signal of the differential demodulator 1205 and the output signal of the hierarchical symbol demapper 2001 at frequency domain and outputs the deinterleaved signal to the symbol demapper 1209. The symbol demapper 1209 performs symbol de-mapping based on QPSK for the enhancement layer stream

TV and the 4 DQPSK modulated base layer stream. The time deinterleaver 1211, the internal decoder 2003, the convolutional decoder 1213, and the energy dispersal descrambler 1214 perform channel decoding. The time deinterleaver 1211 deinterleaves the output signal of the symbol demapper 1209 in a time domain. The convolutional decoder 1213 performs convolutional decoding on the base layer stream which is the output signal of the time deinterleaver 1211. The internal decoder 2003 performs channel decoding for error correction of the enhancement layer stream that is the output signal of the time deinterleaver 1211. The energy dispersal descrambler 1215 rearranges a signal scrambled for energy dispersion by descrambling the output signal of the convolutional decoder 1213 and the output signal of the internal decoder 2003 and outputs the rearranged signal to the base layer receiving processor 1103 and the enhancement layer receiving processor 1903. Fig. 23 is a diagram illustrating a hierarchical DMB receiver of Fig. 21. unlike the hierarchical DMB receiver 1901 of Fig. 22, the hierarchical DMB receiver 1901 of Fig. 23 demodulates the output signal of the FFT 1203 based on ^f DQPSK, the frequency deinterleaver 1207 performs frequency deinterleaving on the output signal of the differential demodulator 1205, and the hierarchical symbol demapper 2001 separates a base layer stream and an enhancement layer stream from the output signal of the frequency deinterleaver 1207. Therefore, it is not necessary to include a frequency deinterleaver for performing frequency deinterleaving on a hierarchically de-mapped enhancement layer stream.

Fig. 24 is a diagram illustrating an enhancement layer receiving processor of Fig. 21.

As shown in Fig. 24, the enhancement layer receiving processor 1903 includes a convolutional deinterleaver 2201, an external decoder 2203, a TS demultiplexer 1119, and a system decoder 1121. The enhancement layer receiving processor 1903 of Fig. 24 processes an enhancement layer stream transmitted through the enhancement layer transmission processor 610 of Fig. 18. Therefore, the enhancement layer receiving processor 1903 performs a decoding operation corresponding to an encoding scheme used at the enhancement layer transmission processor 610 of Fig. 18 to encode the enhancement layer stream. The convolutional deinterleaver 2201 and the external decoder 223 perform channel decoding. The convolubional deinterleaver 2201 disperses concatenated error by deinterleaving the output signal of the hierarchical DMB receiver 1091. The external decoder 2203 corrects an error signal by decoding the output signal of the convolutional deinterleaver 2201. The TS demultiplexer 1119 demultiplexes the output signal of the external decoder 2203 to multimedia and various supplementary information packets. The system decoder 1121 depacketizes the output signal of the TS demultiplexer 1119 and synchronizes streams and outputs the depacketized and synchronized signal to the video decoder 1905 and the audio decoder 1907. For example, the system decoder 1121 may be an MPEG-4 system decoder.

Figs. 25 and 26 are constellations for a Null signal of a base layer stream and a Phase reference signal used in a typical DMB system and a DMB system according to the present invention. Like the typical DMB system, hierarchical modulation is not applied to the Null signal of a base layer stream and a phase reference signal because of compatibility with the typical DMB systems. Therefore, a signal with hierarchical modulation applied means a signal excepting the Null signal of the base layer stream and the phase reference signal.

Fig. 27 is constellation showing hierarchical symbol mapping performed by a hierarchical symbol mapper 601 when a differential modulator 211 modulates a base layer stream signal based on -4- DQPSK in accordance with an embodiment of the present invention. That is, Fig. 27 shows constellation illustrating symbols of an enhancement layer stream that are mapped to each of jr 3τr

(2n+l)^th symbols ^\e * ,Θ^~*^~ ,Θ^~* by the hierarchically symbol mapper 601, where n is an integer number. The constellation of Fig. 27 is equivalent to ^z'.κ of Eq. 2.

As shown in Fig. 27, when a symbol of a 4 DQPSK modulated base layer stream is a (2n+l)^th symbol, the hierarchical symbol mapper 601 performs hierarchical symbol mapping on an enhancement layer stream signal, which is encoded based on QPSK by gray coding, with a base layer stream signal. The gray coding is an encoding method for allocating and mapping bits to make a bit difference between adjacent signals to be 1-bit. According to the gray coding, the maximum possible error of adjacent signals is 1-bit. According to the constellation shown in Fig. 27, the hierarchical symbol mapper 601 performs hierarchical symbol mapping on an enhancement layer stream signal, which is QPSK encoded by gray coding, for (2n+l)^th symbols e * ,e ⁴ ,e ⁴ ,e^~* _of _a base layer stream. That is, the hierarchical symbol mapper 601 performs hierarchical symbol mapping to map the (2n+l) symbols &*,&^'* ,& ⁴ ,e' * _of a base layer stream and symbols of an enhancement layer stream, which are hierarchical symbol mapped with 2n+l)^th symbols e ⁴ ,e ⁴ ,e ^Λ ,e ⁴ of a base layer stream, according to gray coding. Also, the hierarchical symbol mapper 601 performs hierarchical symbol mapping to map the 2n+l)^th symbols e^yϊ,e^J;r,e'^x,e^;^ and the symbols of the enhancement layer stream according to the gray coding.

Fig. 28 is constellation showing hierarchical symbol mapping performed by a hierarchical symbol mapper 601 when a differential modulator 211 modulates a base layers stream based on a 4 DQPSK scheme in accordance with an embodiment of the present invention. That is, Fig. 28 shows constellation illustrating symbols of an enhancement layer stream hierarchically mapped to each of j ,_: _j 3 ;,

(2n)^th symbols &^JO,& ^ύ ,e^J7r,& ^z of a base layer stream by the hierarchical symbol mapper 601. The hierarchical symbol mapped constellation of Fig. 28 is ^zι.ι< of Eq. 2.

As shown in Fig. 28, the hierarchical symbol mapper 601 hierarchically maps symbols of an enhancement layer stream signal, which is modulated based on QPSK by gray coding, with a base layer stream signal. According to the embodiment of Fig. 28, the hierarchical symbol mapper 601 hierarchically maps (2n)^th symbols e^jO,e^J^,e^J~ ,e^J * _of _a base layer stream by shifting phases of symbols of an enhancement layer stream, which is QPSK encoded by gray coding, as much as 4. That is, the hierarchical symbol mapper 601 performs hierarchical symbol mapping to map the (2n)^th symbols &^ja,&^'z ,e^J~,e^{J 2} _of _a base layer stream according to gray coding and to map symbols of an enhancement layer stream, which is QPSK encoded by gray

TT coding, to 4- phase shifting as the symbol of the enhancement layer stream where hierarchical symbol mapping is performed with the (2n)^th symbols &^J°.&'*.&'^*•.&' =^■ of a base layer stream.

As described above, the hierarchical symbol mapper 601 may allocate additional information bits by modulating an enhancement layer stream based on 2-ASK, QPSK, or 16-QAM. The number of supplementary information bits may be 1-bit for 2-ASK, 2-bits for QPSK, and 4-bits for 16-QAM. The supplementary information bits are added to 2-bits allocated to a ^ DQPSK modulated base layer stream.

As shown in Figs. 26 and 27, a ratio ( ^"^ ) of a constellation distance a of a base layer stream symbol and a constellation distance b of an enhancement layer stream may be changed by controlling sizes of a base layer stream signal and an enhancement layer stream signal according to receiving conditions. Receiving conditions may be the intensity of a receiving signal, data performance utility of data included an enhancement layer stream such as a bit error rate (BER) and a packet error rate (PER) .

Table 2 shows a symbol mapping function for constellations of Figs. 27 and 28. In Table 2, CC is _a ratio ^^ of a constellation distance a of a base layer stream symbol b.

Table 2

In Table 2, A denotes an information bit corresponding to ^z/,κ , and B denotes an information bit corresponding to ι,t<.

Fig. 29 is constellation showing hierarchical symbol mapping performed by a hierarchical symbol mapper 601 when a differential modulator 211 modulates a base layers stream based on a -4- DQPSK scheme in accordance with another embodiment of the present invention. That is, Fig. 29 is constellation illustrating symbols of an enhancement layer stream signal hierarchically mapped to

(2n+l)^th symbol of a base layer stream by the hierarchical symbol mapper 601. The hierarchical symbol mapped constellation of Fig. 29 is ^z'.* of Eq. 2. As shown in Fig. 29, the hierarchical symbol mapper 601 hierarchically maps symbols of an enhancement layer stream signal, which is QPSK encoded by gray coding by a symbol mappe 207, with a base layer stream signal when symbols of DQPSK base layer stream are (2n+l)^th symbols. Unlike the constellation of Fig. 27, the hierarchical symbol mapper 601 hierarchically maps a symbol of an enhancement layer stream, which is QPSK encoded by gray coding, to a symbol <&^J^ of a base layer stream. Also, the hierarchical symbol mapper 601 hierarchically maps symbols of the enhancement layer stream to of the base layer stream by performing 2 , TT, and hase-shifting based on a phase of the symbol of the enhancement layer stream tha is hierarchically mapped to the symbol corresponding to Fig. 30 is constellation showing hierarchical symbol mapping performed by a hierarchical symbol mapper 601 when a differential modulator 211 modulates a base layer stream signal based on -^- DQPSK in accordance with another embodiment of the present invention. That is, Fig. 27 shows constellation illustrating symbols of an enhancement layer stream that are mapped to each of (2n)^th symbols by the hierarchically symbol mapper 601, where n is an integer number. The constellation of Fig. 30 is equivalent to '.« of Eq. 2. As shown in Fig. 30, the hierarchical symbol mapper 601 hierarchically maps symbols of an enhancement layer stream signal, which is QPSK encoded by gray coding by a symbol mapper 207, with a base layer stream signal when symbols of DQPSK base layer stream are (2n)^th symbols. According to an embodiment of the Fig. 30, the hierarchical symbol mapper 601 hierarchically maps a symbol of an enhancement layer stream by shifting a phase of the symbol of the enhancement layer stream, which is

QPSK encoded by gray coding, as much as 4 for a symbol © ² of a base layer stream and hierarchically maps symbols of the enhancement layer stream signal for symbols ^{&M e 2} -^&J° of the base layer stream by performing

2 , TT , and ^~~2^™ phase shifting based on a phase of the symbol of the enhancement layer stream which is hierarchically mapped to the symbol © ² of the base layer stream.

As described above, the hierarchical symbol mapper 601 may allocate additional information bits by modulating an enhancement layer stream based on 2-ASK, QPSK, or 16-QAM. The number of supplementary information bits may be 1-bit for 2-ASK, 2-bits for QPSK, and 4-bits for 16-QAM. The supplementary information bits are added to 2-bits allocated to a ^- DQPSK modulated base layer stream. Table 3 shows a symbol mapping function for constellation shown in Figs. 29 and 30. In Table 3, OC is a ratio ^2^~ of a constellation distance a of a base layer stream symbol b.

Table 3

In Table 3, A denotes an information bit corresponding to /.*^• , and B denotes an information bit corresponding to ^/,*r.

Fig. 31 is constellation showing hierarchical symbol mapping performed by a hierarchical symbol mapper 601 when a differential modulator 211 modulates a base layer stream signal based on 4 DQPSK in accordance with another embodiment of the present invention. That is, Fig. 27 shows constellation illustrating symbols of an enhancement layer stream that are mapped to each of (2n+l)^th symbols &* ,e ^,e^Jτ,e^y"4" by the hierarchically symbol mapper 601, where n is an integer number. The constellation of Fig. 31 is equivalent to ^z'.^fc of Eq. 2.

As shown in Fig. 31, when symbols of a -^- DQPSK base layer stream are (2n+l)^th symbols, the hierarchically symbol mapper 601 hierarchically maps symbols of an enhancement layer stream signal, which is encoded by the symbol mapper 207 based on QPSK through gray coding, with a base layer stream signal. According to the Fig. 31, the hierarchical symbol mapper 601 hierarchically maps symbols of an enhancement layer stream signal, which is QPSK encoded by gray coding, for a symbol ^eJΛ^Λ of a base layer stream. Here, bit allocation according to gray coding of Fig. 31 is different from bit allocation of Fig. 29. The hierarchical symbol mapper 601 hierarchically maps symbols of an enhancement layer stream signal for symbols <≡*^J^, &^J^^ir, &^J~-* of the base layer stream by performing ^~-Ξ=T , ¹K , ^~=≡>^~ phase shifting based on a phase of the symbol of the enhancement layer stream which is hierarchically symbol mapped for the symbol <≡»^v "* of a base layer stream.

Fig. 32 is constellation showing hierarchical symbol mapping performed by a hierarchical symbol mapper 601 when a differential modulator 211 modulates a base layer stream signal based on ^ DQE³SK in accordance with still another embodiment of the present invention. That is, Fig. 32 shows constellation illustrating symbols of an enhancement layer stream that are mapped for (2n)^th symbols e^J°,&^Jz ,&^Jrr,e^{J 2} by the hierarchically symbol mapper 601, where n is an integer number. The constellation of Fig. 32 is equivalent to ^z'.κ of Eq. 2.

As shown in Fig. 32, the hierarchical symbol mapper 601 hierarchically maps symbols of an enhancement layer stream signal, which is QPSK encoded by gray coding by a symbol mapper 207, with a base layer stream signal when

TT^~ symbols of ^T DQPSK base layer stream are (2n)^th symbols. According to an embodiment of the Fig. 32, the hierarchical symbol mapper 601 hierarchically maps a symbol of an enhancement layer stream by shifting a phase of the symbol of the enhancement layer stream, which is

TC QPSK encoded by gray coding, as much as ^- for a symbol © ² of a base layer stream. Here, bit allocation according to gray coding of Fig. 32 is different from that of Fig. 30. The hierarchical symbol mapper 601 hierarchically maps symbols of an enhancement layer stream for symbols ^eJ">^{e 2} >^eJ of a base layer stream by performing ^ , TT , and 2 phase shifting based on a phase of the symbol of the enhancement layer stream hierarchically mapped for the symbol ^{β 2} of a base layer stream.

As described above, the hierarchical symbol mapper 601 may allocate additional information bits by modulating an enhancement layer stream based on 2-ASK, QPSK, or 16-QAM. The number of supplementary information bits may be 1-bit for 2-ASK, 2-bits for QPSK, and 4-bits for 16-QAM. The supplementary information bits are added to 2-bits allocated to a -*f DQPSK modulated base layer stream.

Table 4 shows a symbol mapping function for constellations of Figs. 31 and 32. In Table 4, OC is a ratio ^~^^~ of a constellation distance a of a base layer stream symbol b.

Table 4

In Table 4, A denotes an information bit corresponding to ^■'.*^■ , and B denotes an information bit corresponding to -1 , K .

37 Fig. 33 is a diagram illustrating a transmitter in accordance with an embodiment of the present invention.

Differences between the transmitters of Figs. 17 and Fig. 33 are an enhancement layer transmission processor 3101 and a hierarchical DAB transmitter 309. The hierarchical DAB transmitter 309 was described with reference to Fig. 6, and the enhancement layer transmission processor 3101 will be described with reference to Fig. 34. Fig. 34 is a diagram illustrating an enhancement layer transmission processor of Fig. 33.

The enhancement layer transmission processor 3101 of Fig. 34 includes a system encoder 401, a TS multiplexer 403, an external encoder 1601, a convolutional interleaver 111, an energy dispersal scrambler 201, an internal encoder 1701, a time interleaver 205, a symbol mapper 207, and a frequency interleaver 209. The constituent elements of the enhancement layer transmission processor 3101 are identical to those included in the enhancement layer transmission processor 1509 and the hierarchical DMB transmitter 1511 shown in Figs. 18 to 20.

Fig. 35 is a diagram ilLustrating a receiver in accordance with an embodiment of the present invention. Differences between the receivers of Figs. 21 and 35 are a hierarchical DAB receiver 1101 and an enhancement layer receiving processor 3301. The hierarchical DAB receiver 1101 was described with reference to Fig. 14, and the enhancement layer receiving processor 3301 will be described with reference to Fig. 36.

Fig. 36 is a diagram illustrating an enhancement layer receiving processor of Fig. 35. That is, the enhancement layer receiving processor of Fig. 36 has a structure corresponding to the structure of the enhancement layer transmission processor 3101 of Fig. 34. As shown in Fig. 36, the enhancement layer receiving processor 3301 includes a hierarchical symbol demapper 2001, a frequency deinterleaver 1207, a symbol demapper 1209, a time deinterleaver 1211, an internal decoder 2003 and an energy dispersal descrambler 1214, a convoluti onal deinterleaver 2201, an external decoder 2203, a TS demultiplexer 1119, and a system decoder 1121. The constituent elements of the enhancement layer receiving processor 3301 are identical to those included in the enhancement layer receiving processor 730 and the hierarchical DMB transmitter 710 shown in Figs. 22 and 24,

As described above, the base layer transmission processor 307 is commonly used in the transmitters shown in Figs. 3, 12, and 17. Similarly, the base layer receiving processor 1103 is commonly used in the receivers shown in Figs. 13, 16, and 21.

Meanwhile, the enhancement layer transmission processor 305 and the hierarchical DAB transmitter 309 included in the transmitters shown in Figs. 3 and 13 can be replaced with the enhancement layer transmission processor 1509 and the hierarchical DMB transmitter 1511 included in the transmitter of Fig. 17. Similarly, the enhancement layer receiving processor 1105 and the hierarchical DAB receiver 1101 included in the receivers of Figs. 13 and 16 may be replaced with the enhancement layer receiving processor 1903 and the hierarchical DMB receiver 1901 included in the Fig. 21.

According to the present invention, a stream of an MSC can be processed to an enhancement layer stream by applying hierarchical modulation. Also, a stream of a FIC providing system information can be processed to an enhancement layer stream by applying hierarchical modulation. Information about hierarchical modulation is transmitted through a FIC. The information about hierarchical modulation may include whether hierarchical modulation is applied or not, a hierarchical modulation scheme, a coding rate of a channel encoder, and information about services related to an enhancement layer. The receiver according to the present invention receives the transmitted enhancement layer information.

Although the present invention was described in a mechanical view point throughout the specification, the operations of the constituent elements of the transmitter and the receiver according to the present invention can be easily understood in a process view point. Therefore, the operations of the constituent elements of the transmitter and the receiver according to the present invention can be understood as steps forming a transmitting method and a receiving method according to the scope of the present invention.

While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.

Claims

WHAT IS CLAIMED IS:

1. A digital multimedia broadcasting (DMB) transmitter, comprising: a base layer transmission processing means for encoding base layer stream; an enhancement layer transmission processing means for encoding enhancement layer stream; and a hierarchical transmitting means for transmitting the base layer stream and the enhancement layer stream by encoding the base layer stream outputted from the base layer transmission processing means and the enhancement layer stream outputted from the enhancement layer transmission processing means based on gray coding, allocating predetermined bit values thereto, and performing hierarchical symbol mapping.

2. The DMB transmitter of claim 1, wherein the hierarchical transmitting means encodes the base layer stream based on 4 differential quadrature phase shift keying (DQPSK) and allocates a predetermined bit value, while encoding the enhancement layer stream based on quadrature phase shift keying (QPSK) according to gray coding and allocating a predetermined bit value, and performs hierarchical symbol mapping on the encoded base layer stream and the encoded enhancement layer stream.

3. The DMB transmitter of claim 2, wherein the hierarchical transmitting means performs hierarchical symbol mapping to map (2n+l)^th symbols <≡>^J* ,*≡>^J~,&^J"-^r,&^J~^ of the encoded base layer stream and symbols of an enhancement layer stream according to gray coding where n is an integer number.

4. The DMB transmitter of claim 3, wherein the hierarchical transmitting means performs hierarchical symbol mapping to map (2n)^th symbols &^jO,&^Jz ,&^{J^}, <≡>^{J 2} of the encoded base layer stream according to gray coding and to map symbols of an enhancement layer stream where hierarchical symbol mapping is performed with the (2n) th

7T symbols to phase shift.

5. The DMB transmittei of claim 4, wherein the hierarchical transmitting means performs hierarchical symbol mapping onto the encoded base layer stream and the encoded enhancement ]ayer stream according to a following table 1:

Table 1

where A denotes bit values corresponding to symbols of the encoded enhancement layer stream and B denotes bit values corresponding symbols of the encoded base layer stream.

6. The DMB transmitter of claim 4, wherein the hierarchical transmitting means includes: an energy dispersal scrambler for dispersing energy of the base layer stream outputted from the base layer transmission processing means and dispersing energy of the enhancement layer stream outputted from the enhancement layer transmission processing means; an internal encoder for performing error correction coding onto an enhancement layer stream outputted from the energy dispersal scrambler; a convolutional encoder for performing convolutional encoding onto a base layer stream outputted from the energy dispersal scrambler; a time interleaver for performing time interleaving onto an enhancement layer stream outputted the internal encoder and a base layer stream outputted from the convolutional encoder; and a symbol mapper for allocating a predetermined bit value by encoding an enhancement layer stream and a base layer stream outputted from the time interleaver based on QPSK according to gray coding.

7. The DMB transmitter of claim 6, wherein the hierarchical transmitter further includes: a frequency interleaver for performing frequency interleaving onto an enhancement layer stream and a base layer stream outputted from the symbol mapper; a differential modulator for encoding a base layer stream outputted from the frequency interleaver based on ^"5T DQPSK; and a hierarchical symbol mapper for performing the hierarchical symbol mapping onto an enhancement layer stream outputted from the frequency interleaver and a base layer stream outputted from the differential modulator.

8. The DMB transmitter of claim 7, wherein the enhancement layer transmission processing means includes: a system encoder for performing objectivation and synchronization onto an enhancement layer multimedia stream; a transport stream (TS) multiplexer for multiplexing an output signal of the system encoder into an enhancement layer stream; an external encoder for performing channel coding onto an output signal of the TS multiplexer; and a convolutional interleaver for generating a temporal correlation-removed signal by removing temporal correlation between adjacent unit bytes from an output signal of the external encoder and outputting the temporal correlation-removed signal to the hierarchical transmitting means.

9. The DMB transmitter of claim 6, wherein the hierarchical transmitting means further includes: a hierarchical symbol mapper for performing the hierarchical symbol mapping onto an enhancement layer stream and a base layer stream outputted from the symbol mapper; a frequency interleaver for performing frequency interleaving onto an output signal of the hierarchical symbol mapper; and a differential modulator for encoding an output signal of the frequency interleaver based on ^- DQPSK.

10. The DMB transmitter of claim 9, wherein the enhancement layer transmission processing means includes: a system encoder for performing objectivation and synchronization onto an enhancement layer multimedia stream; a TS multiplexer for multiplexing an output signal of the system encoder into an enhancement layer stream; an external encoder for performing channel coding onto an output signal of the TS multiplexer; and a convolutional interleaver for generating a temporal correlation-removed signal by removing temporal correlation between adjacent unit bytes from an output signal of the external encoder and outputting the temporal correlation-removed signal to the hierarchical transmitting means .

11. The DMB transmitter of claim 4, wherein the hierarchical transmitting means includes: an energy dispersal scrambler for dispersing energy of a base layer stream outputted from the base layer transmission processing means; a convolutional encoder for performing convolutional encoding onto a base layer stream outputted from the energy dispersal scrambler; a time interleaver for performing time interleaving onto a base layer stream outputted from the convolutional encoder; a symbol mapper for allocating a predetermined bit value by encoding a base layer stream outputted from the time interleaver based on QPSK according to gray coding; a frequency interleaver for performing frequency interleaving onto a base layer stream outputted from the symbol mapper; a differential modulator for encoding a base layer stream outputted from the frequency interleaver based on ^ DQPSK; and a hierarchical symbol mapper for performing the hierarchical symbol mapping onto a base layer stream outputted from the differential modulator and an enhancement layer stream outputted from the enhancement layer transmission processing means.

12. The DMB transmitter of claim 11, wherein the enhancement layer transmission processing means includes: a system encoder for performing objectivation and synchronization onto an enhancement layer multimedia stream; a TS multiplexer for multiplexing an output signal of the system encoder into an enhancement layer stream; an external encoder for performing channel coding onto an output signal of the TS multiplexer; a convolutional interleaver for removing temporal correlation between adjacent unit bytes from an output signal of the external encoder; an energy dispersal scrambler for dispersing energy of an output signal of the convolutional interleaver; an internal encoder for performing internal encoding onto an output signal of the energy dispersal scrambler; a time interleaver for performing time interleaving onto an output signal of the internal encoder; a symbol mapper for allocating a predetermined bit value by encoding an output signal of the time interleaver based on QPSK according to gray coding; and a frequency interleaver for performing frequency interleaving onto an output signal of the symbol mapper to thereby generate an interleaved signal and outputting the interleaved signal to the hierarchical transmitting means .

13. The DMB transmitter of claim 2, wherein the hierarchical transmitting means performs hierarchical symbol mapping without phase-shifting a symbol of an enhancement layer stream where hierarchical symbol mapping is performed with a symbol corresponding to ^{& 4} of the encoded base layer stream among symbols of the encoded enhancement layer stream.

14. The DMB transmitter of claim 13, wherein the hierarchical transmitting means performs hierarchical symbol mapping by ^"s^" , TT _f and 2 phase-shifting a symbol of an enhancement layer stream where hierarchical symbol mapping is performed with symbols corresponding to

<≡^^^~> o^y^^, <3^J^^~ of the encoded base layer stream among symbols of the encoded enhancement layer stream based on a phase of a symbol of an enhancement layer stream where hierarchical symbol mapping is performed with a symbol corresponding to <s^^* of the encoded base layer stream.

15. The DMB transmitter of claim 14, wherein the hierarchical transmitting means performs hierarchical

TT symbol mapping by -4 phase-shifting a symbol of an enhancement layer stream where hierarchical symbol mapping is performed with a symbol corresponding to e^² of the encoded base layer stream among symbols of the encoded enhancement layer stream.

16. The DMB transmitter of claim 15, wherein the hierarchical transmitting means performs hierarchical

Z∑_ _ ^ZH. symbol mapping by => , 7T , and ^' =≥ phase-shifting symbols of an enhancement layer stream where hierarchical symbol mapping is performed with symbols corresponding to ^&J" -.^{& 2} '^&JO of the encoded base layer stream among symbols of the encoded enhancement layer stream based on a phase of a symbol of an enhancement layer stream where hierarchical symbol mapping is performed with a symbol corresponding to & ² of the encoded base layer stream.

17. The DMB transmitter of claim 16, wherein the hierarchical transmitting means performs hierarchical symbol mapping on the encoded base layer stream and the encoded enhancement layer stream according to a following table 2:

Table 2

where A denotes bit values corresponding to symbols of the encoded enhancement layer stream and B denotes bit values corresponding to symbols of the encoded base layer stream.

18. The DMB transmitter of claim 16, wherein the hierarchical transmitting means performs hierarchical symbol mapping on the encoded base layer stream and the encoded enhancement layer stream according to a following table 3:

Table 3

19. The DMB transmitter of claim 16, wherein the hierarchical transmitting means includes: an energy dispersal scrambler for dispersing energy of a base layer stream outputted from the base layer transmission processing means and dispersing energy of an enhancement layer stream outputted from the enhancement layer transmission processing means; an internal encoder for performing internal encoding onto an enhancement layer stream outputted from the energy dispersal scrambler; a convolutional encoder for performing convolutional encoding onto a base layer stream outputted from the energy dispersal scrambler; a time interleaver for performing time interleaver onto an enhancement layer stream outputted from the internal encoder and a base Layer stream outputted from the convolutional encoder; and a symbol mapper for allocating a predetermined bit value by encoding an enhancement layer stream and a base layer stream outputted from the time interleaver based on QPSK according to gray coding.

20. The DMB transmitter of claim 19, wherein the hierarchical transmitting means further includes: a frequency interleaver for performing frequency interleaving onto an enhancement layer stream and a base layer stream outputted from the symbol mapper; a differential modulator for encoding a base layer stream outputted from the frequency interleaver based on ^~^ DQPSK; and a hierarchical symbol mapper for performing the hxerarchical symbol mapping onto an enhancement layer stream outputted from the frequency interleaver and a base layer stream outputted from the differential modulator.

21. The DMB transmitter of claim 20, wherein the enhancement layer transmission processing means includes: a system encoder for performing objectivation and synchronization onto an enhancement layer multimedia stream; a TS multiplexer for multiplexing an output signal of the system encoder into an enhancement layer stream; an external encoder for performing channel coding onto an output signal of the TS multiplexer; and a convolutional interleaver for removing temporal correlation between adjacent unit bytes from an output signal of the external encoder to thereby generate a temporal correlation-removed signal and outputting the temporal correlation-removed signal to the hierarchical transmitting means.

22. The DMB transmitter of claim 19, wherein the hierarchical transmitting means further includes: a hierarchical symbol mapper for performing the hierarchical symbol mapping onto an enhancement layer stream and a base layer stream outputted from the symbol mapper; a frequency interleaver for performing frequency interleaving onto an output signal of the hierarchical symbol mapper; and a differential modulator for encoding an output

TT signal of the frequency interleaver based on ■«* DQPSK.

23. The DMB transmitter of claim 22, wherein the enhancement layer transmission processing means includes: a system encoder for performing objectivation and synchronization onto an enhancement layer multimedia stream; a TS multiplexer for multiplexing an output signal of the system encoder into an enhancement layer stream; an external encoder for performing channel coding onto an output signal of the TS multiplexer; and a convolutional interleaver for removing temporal correlation between adjacent unit bytes, from an output signal of the external encoder to thereby generate a temporal correlation-removed signal and outputting the temporal correlation-removed signal to the hierarchical transmitting means.

24. The DMB transmitter of claim 16, wherein the hierarchical transmitting means includes: an energy dispersal scrambler for dispersing energy of a base layer stream outputted from the base layer transmission processing means; a convolutional encoder for performing convolutional encoding onto a base layer stream outputted from the energy dispersal scrambler; a time interleaver for performing time interleaving onto a base layer stream outputted from the convolutional encoder; a symbol mapper for allocating a predetermined bit value by encoding a base layer stream outputted from the time interleaver based on QPSK according to gray coding; a frequency interleaver for performing frequency interleaving onto a base layer stream outputted from the symbol mapper; a differential modulator for encoding a base layer stream outputted from the frequency interleaver based on ^~^ DQPSK; and a hierarchical symbol mapper for performing the hierarchical symbol mapping onto a base layer stream outputted from the differential modulator and an enhancement layer stream outputted from the enhancement layer transmission processing means.

25. The DMB transmitter of claim 24, wherein the enhancement layer transmission processing means includes: a system encoder for performing objectivation and synchronization onto an enhancement layer multimedia stream; a TS multiplexer for multiplexing an output signal of the system encoder into an enhancement layer stream; an external encoder for performing channel coding onto an output signal of the TS multiplexer; a convolutional interleaver for removing temporal correlation between adjacent unit bytes from an output signal of the external encoder; an energy dispersal scrambler for dispersing energy of an output signal of the convolutional interleaver; an internal encoder for performing internal encoding onto an output signal of the energy dispersal scrambler; a time interleaver for performing time interleaving onto an output signal of the internal encoder; a symbol mapper for allocating a predetermined bit value by encoding an output signal of the time interleaver based on QPSK according to gray coding; and a frequency interleaver for performing frequency interleaving onto an output signal of the symbol mapper to thereby generate an interleaved signal and outputting the interleaved signal to the hierarchical transmitting means .

26. The DMB transmitter of claim 1, further comprising a scalable multimedia encoder for converting a multimedia source to an enhancement layer stream and a base layers stream, outputting the base layer stream to the base layer transmission processing means, and outputting the enhancement layer stream to the enhancement layer transmission processing means.

27. The DMB transmitter of claim 1, further comprising: a supplementary data source encoder for converting a supplementary data source into an enhancement layer stream and outputting the enhancement layer stream to the enhancement layer transmission processing means; and a multimedia encoder for converting a multimedia source into a base layer stream and outputting the base layer stream to the base layer transmission processing means .

28. The DMB transmitter of claim 1, further comprising : a first multimedia encoder for converting a first multimedia source into a base layer stream and outputting the base layer stream to the base layer transmission processing means; and a second multimedia encoder for converting a second multimedia source independent from the first multimedia source to an enhancement layer stream and outputting the enhancement layer stream to the enhancement layer transmission processing means.

29. The DMB apparatus of claim 1, wherein the base layer transmission processing means includes: a system encoder for performing objectivation and synchronization onto a base layer multimedia stream; a TS multiplexer for multiplexing an output signal of the system encoder into a base layer stream; a Reed-Solomon (RS) encoder for performing additional error control coding onto an output signal of the TS multiplexer; and a convolutional interleaver for removing temporal correlation between adjacent unit bytes from an output signal of the RS encoder to thereby generate a temporal correlation-removed signal and outputting the temporal correlation-removed signal to the hierarchical transmitting means.

30. A digital multimedia broadcasting (DMB) transmitter, comprising: a base layer transmission processing means for encoding base layer stream; an enhancement layer transmission processing means for encoding enhancement layer stream; and a hierarchical transmitting means for encoding a base layer stream outputted from the base layer transmission processing means based on 4 DQPSK and allocating a predetermined bit value, while encoding an enhancement layer stream outputted from the enhancement layer transmission processing means based on QPSK and allocating a predetermined bit value, and performing hierarchical symbol mapping onto the encoded base layer stream and the coed enhancement layer stream.

31. The DMB transmitter of claim 30, wherein the hierarchical transmitting means performs hierarchical symbol mapping onto the encoded base layer stream and the encoded enhancement layer stream according to a following table 4:

Table 4

32. The DMB transmitter of claim 30, wherein the hierarchical transmitting means includes: an energy dispersal scrambler for dispersing energy of a base layer stream outputted from the base layer transmission processing means; a convolutional encoder for performing convolutional encoding onto a base layer stream outputted from the energy dispersal scrambler; a time interleaver for performing time interleaving onto a base layer stream outputted from the convolutional encoder; a symbol mapper for encoding a base layer stream outputted from the time interleaver based on QPSK according to gray coding and allocating a predetermined bit value; a frequency interleaver for performing frequency interleaving onto a base layer stream outputted from the symbol mapper; a differential modulator for encoding a base layer stream outputted from the frequency interleaver based on ^"^ DQPSK; and a hierarchical symbol mapper for performing the hierarchical symbol mapping onto a base layer stream outputted from the differential modulator and an enhancement layer stream outputted from the enhancement layer transmission processing means.

33. The DMB transmitter of claim 32, wherein the enhancement layer transmission processing means includes: a system encoder for performing objectivation and synchronization onto an enhancement layer multimedia stream; a TS multiplexer for multiplexing an output signal of the system encoder into an enhancement layer stream; an energy dispersal scrambler for dispersing energy of an enhancement layer stream outputted from the TS multiplexer; a channel encoder for performing channel encoding onto an output signal of the energy dispersal scrambler; and a time interleaver for performing time interleaving onto an output signal of the channel encoder to thereby generate an interleaved signal and outputting the interleaved signal to the hierarchical transmitting means.

34. A digital multimedia broadcasting (DMB) transmitter, comprising: a base layer transmission processing means for encoding base layer stream; an enhancement layer transmission processing means for encoding enhancement layer stream; and a hierarchical transmitting means for encoding a base layer stream outputted from the base layer

7T transmission processing means based on ^- DQPSK and allocating a predetermined bit value, while encoding an enhancement layer stream outputted from the enhancement layer transmission processing means based on 2-amplitude shift keying (2-ASK) and allocating a predetermined bit value, and performing hierarchical symbol mapping onto the encoded base layer stream and the encoded enhancement layer stream.

35. The DMB transmitter of claim 34, wherein the hierarchical transmitting means performs hierarchical symbol mapping onto the encoded base layer stream and the encoded enhancement layer stream using a following equation 1:

where ^zι,κ denotes 1^th to k^th QPSK symbols of the encoded base layer stream, and ^zι.κ denotes 1^th to k^th carriers of the encoded enhancement layer stream.

36. The DMB transmitter of claim 34, wherein the hierarchical transmitting means includes: an energy dispersal scrambler for dispersing energy of a base layer stream outputted from the base layer transmission processing means; a convolutional encoder for performing convolutional encoding onto a base layer stream outputted from the energy dispersal scrambler; a time interleaver for performing time interleaving onto a base layer stream outputted from the convolutional encoder; a symbol mapper for encoding a base layer stream outputted from the time interleaver based on QPSK according to gray coding and allocating a predetermined bit value; a frequency interleaver for performing frequency interleaving onto a base layer stream outputted from the symbol mapper; a differential modulator for encoding a base layer stream outputted from the frequency interleaver based on ^T DQPSK; and a hierarchical symbol mapper for performing the hierarchical symbol mapping on a base layer stream outputted from the differential modulator and an enhancement layer stream outputted from the enhancement layer transmission processing means.

37. The DMB transmitter of claim 36, wherein the enhancement layer transmission processing means includes: a system encoder for performing objectivation and synchronization on an enhancement layer multimedia stream; a TS multiplexer for multiplexing an output signal of the system encoder into an enhancement layer stream; an energy dispersal scrambler for dispersing energy of an enhancement layer stream outputted from the TS multiplexer; a channel encoder for performing channel encoding onto an output signal of the energy dispersal scrambler; and a time interleaver for performing time interleaving onto an output signal of the channel encoder to thereby generate an interleaved signal and outputting the interleaved signal to the hierarchical transmitting means.

38. A digital multimedia broadcasting (DMB) receiver, comprising: a hierarchical receiving means for separating an encoded base layer stream and an encoded enhancement layer stream from a receiving signal by performing hierarchical symbol de-mapping onto the receiving signal where a predetermined bit value is allocated and hierarchical symbol is mapped through encoding according to gray coding; a base layer receiving processing means for decoding the encoded base layer stream; and an enhancement layer receiving processing means for decoding the encoded enhancement layer stream.

39. The DMB receiver of claim 38, wherein the receiving signal is processed by performing hierarchical symbol mapping onto the encoded base layer stream and the encoded enhancement layer stream, and the hierarchical symbol mapping is performed by allocating a predetermined bit value through encoding a base layer stream based on DQPSK and allocating a predetermined bit value through encoding an enhancement layer stream based on QPSK according to gray coding.

40. The DMB receiver of claim 39, wherein the receiving signal is processed by performing hierarchical symbol mapping to map (2n+l)^th symbols _of the encoded base layer stream and symbols of an enhancement layer stream where hierarchical symbol mapping is performed with the (2n+l)^th symbols according to gray coding and to map the

(2n+l)^th symbols ,e'⁷ and the symbols of the enhancement layer stream according to gray coding where n is an integer number.

41. The DMB receiver of claim 40, wherein the receiving signal is processed by performing hierarchical symbol mapping to map (2n)^th symbols _of the coded base layer stream according to gray coding and to map symbols of an enhancement layer stream where hierarchical symbol mapping is performed with the (2n)^th symbols phase shift.

42. The DMB receiver of claim 41, wherein the receiving signal is processed by performing hierarchical symbol mapping for the encoded base layer stream and the encoded enhancement layer stream according to a following table 1:

Table 1

43. The DMB receiver of claim 41, wherein the hierarchical receiving means includes: a symbol demapper for performing symbol de-mapping onto an enhancement layer stream and a base layer stream included in the receiving signal based on QPSK; a time deinterleaver for deinterleaving a base layer stream and an enhancement layer stream outputted from the symbol demapper in a time domain; a convolutional decoder for performing convolutional decoding onto a base layer stream outputted from the time interleaver; an internal decoder foi performing error control decoding onto an enhancement layer stream outputted from the time deinterleaver; and an energy dispersal descrambler for generating a descrambled base layer stream and a descrambled enhancement layer stream by descrambling a base layer stream outputted from the convolutional decoder and an enhancement layer stream outputted from the internal decoder to rearrange a signal scrambled for energy dispersion and outputting the descrambled base layer stream and the descrambled enhancement layer stream to the base layer receiving processing means and the enhancement layer receiving processing means.

44. The DMB receiver of claim 43, wherein the hierarchical receiving means further includes: a hierarchical symbol demapper for separating the enhancement layer stream from the receiving signal; a differential demodulator for outputting the base layer stream by demodulating the receiving signal based

TV on ^"4^" DQPSK; and a frequency deinterleaver for generating a deinterleaved base layer stream and a deinterleaved enhancement layer stream by deinterleaving a base layer stream outputted from the differential demodulator and an enhancement layer stream outputted from the hierarchical symbol demapper in a frequency domain and outputting the deinterleaved base layer stream and the deinterleaved enhancement layer stream to the symbol demapper.

45. The DMB receiver of claim 44, wherein the enhancement layer receiving processing means includes: a convolutional deinterleaver for dispersing concatenated error by deinterleaving an enhancement layer stream outputted from the hierarchical receiving means; an external decoder for correcting an error signal by decoding an output signal of the convolutional deinterleaver; a transmit stream (TS) demultiplexer for demultiplexing an output signa] of the external decoder to a multimedia and various supplementary information packets; and a system decoder for depacketizing an output signal of the TS demultiplexer and synchronizing streams.

46. The DMB receiver of claim 43, wherein the hierarchical receiving means further includes: a differential demodulator for demodulating the receiving signal based on ^- DQPSK; a frequency deinterleaver for deinterleaving an output signal of the differential demodulator in a frequency domain; and a hierarchical symbol demapper for separating the base layer stream and the enhancement layer stream from an output signal of the frequency deinterleaver and outputting the base layer stream and the enhancement layer stream to the symbol demapper.

47. The DMB receiver of claim 46, wherein the enhancement layer receiving processing means includes: a convolutional deinterleaver for dispersing concatenated error by deinterleaving an enhancement layer stream outputted from the hierarchical receiving means; an external decoder for correcting an error signal by decoding an output signal of the convolutional deinterleaver; a TS demultiplexer for demultiplexing an output signal of the external decoder into multimedia and various supplementary information packets; and a system decoder for depacketizing an output signal of the TS demultiplexer and synchronizing streams.

48. The DMB receiver of claim 41, wherein the hierarchical receiving means includes: a differential demodulator for demodulating the receiving signal based on -^ DQPSK; a frequency deinterleaver for deinterleaving an output signal of the differential demodulator in a frequency domain to thereby generate a deinterleaved signal and outputting the deinterleaved signal to the enhancement layer receiving processing means; a symbol demapper for performing symbol de-mapping onto a base layer stream included in an output signal of the frequency deinterleaver based on QPSK; a time deinterleaver for deinterleaving a base layer stream outputted from the symbol demapper in a time domain; a convolutional decoder for performing convolutional decoding onto a base layer stream outputted from the time deinterleaver; and an energy dispersal descrambler for descrambling a base layer stream outputted from the convolutional decoder to rearrange a signal scrambled for energy dispersion and outputting the descrambled base layer stream to the base layer receiving processing means.

49. The DMB receiver of claim 48, wherein the enhancement layer receiving processing means includes: a hierarchical symbol demapper for separating the enhancement layer stream from an output signal of the frequency deinterleaver; a frequency deinterleaver for deinterleaving an enhancement layer stream outputted from the hierarchical symbol demapper in a frequency domain; a symbol demapper for performing symbol de-mapping onto an enhancement layer stream outputted from the frequency deinterleaver based on QPSK; a time deinterleaver for deinterleaving an enhancement layer stream outputted from the symbol demapper in a time domain; an internal decoder for performing error control decoding onto an enhancement layer stream outputted from the time deinterleaver; an energy dispersal descrambler for rearranging a signal scrambled for energy dispersion by descrambling an enhancement layer stream outputted from the internal decoder; a convolutional deinterleaver for dispersing concatenated error by deinterleaving an enhancement layer stream outputted from the energy dispersal descrambler; an external decoder for correcting an error signal by decoding an output signal of the convolutional deinterleaver; a TS demultiplexer for demultiplexing an output signal of the external decoder to multimedia and various supplementary information packets; and a system decoder for depacketizing an output signal of the TS demultiplexer and synchronizing streams.

50. The DMB receiver of claim 39, wherein the receiving signal is processed by performing hierarchical symbol mapping without phase-shifting a symbol of an enhancement layer stream where hierarchical symbol mapping is performed with a symbol corresponding to <=> ^Λ of the encoded base layer stream among symbols of the encoded enhancement layer stream.

51. The DMB receiver of claim 50, wherein the receiving signal is processed by performing hierarchical symbol mapping by 2 , 71 _r and ϊ≥ phase-shifting a symbol of an enhancement layer stream where hierarchical symbol mapping is performed with symbols corresponding to θ⁴ • ^* ^"* " ^{& 4} of the encoded base layer stream among symbols of the encoded enhancement layer stream based on a phase of a symbol of an enhancement layer stream where hierarchical symbol mapping is performed with a symbol corresponding to ^{e Λ} of the encoded base layer stream.

52. The DMB receiver of claim 51, wherein the receiving signal is processed by performing hierarchical symbol mapping by 4^" phase-shifting a symbol of an enhancement layer stream where hierarchical symbol mapping is performed with a symbol corresponding to e ² of the encoded base layer stream among symbols of the encoded enhancement layer stream.

53. The DMB receiver of claim 52, wherein the receiving signal is processed by performing hierarchical

-π- i³'^ symbol mapping by s , TT, and ^~zT phase-shifting symbols of an enhancement layer stream where hierarchical symbol mapping is performed with symbols corresponding to o^{y^} » ^ ² > ^&J of the encoded base layer stream among symbols of the encoded enhancement layer stream based on a phase of a symbol of an enhancement layer stream where hierarchical symbol mapping is performed with a symbol corresponding to © ² of the encoded base layer stream.

54. The DMB receiver of claim 53, wherein the receiving signal is processed by performing hierarchical symbol mapping onto the encoded base layer stream and the encoded enhancement layer stream according to a following table 2:

Table 2

where A denotes bit values; corresponding to symbols of the encoded enhancement layer stream and B denotes bit values corresponding to symbols of the encoded base layer stream.

55. The DMB receiver of claim 53, wherein the receiving signal is processed by performing hierarchical symbol mapping onto the encoded base layer stream and the encoded enhancement layer stream according to a following table 3:

Table 3

56. The DMB receiver of claim 53, wherein the hierarchical receiving means includes: a symbol demapper for performing symbol de-mapping onto an enhancement layer stream and a base layer stream included in the receiving signal based on QPSK; a time deinterleaver for deinterleaving a base layer stream and an enhancement layer stream outputted from the symbol demapper in a time domain; a convolutional decoder for convolutional-decoding a base layer stream outputted from the time deinterleaver; an internal decoder for performing error control decoding onto an enhancement layer stream outputted from the time deinterleaver; and an energy dispersal descrambler for generating descrambled base layer stream and a descrambled enhancement layer stream by descrambling a base layer stream outputted from the convolutional decoder and an enhancement layer stream outputted from the internal decoder to rearrange a signal scrambled for energy dispersion and outputting the descrambled base layer stream and the descrambled enhancement layer stream to the base layer receiving processing means and the enhancement layer receiving processing means.

57. The DMB receiver of claim 56, wherein the hierarchical receiving means further includes: a hierarchical symbol demapper for separating the enhancement layer stream from the receiving signal; a differential demodulator for outputting the base layer stream by demodulating the receiving signal based on 4^~ DQPSK; and a frequency deinterleaver for generating a deinterleaved base layer stream and a deinterleaved enhancement layer stream by deinterleaving a base layer stream outputted from the differential demodulator and an enhancement layer stream outputted from the hierarchical symbol demapper in a frequency domain and outputting the deinterleaved base layer stream and the deinterleaved enhancement layer stream to the symbol demapper.

58. The DMB receiver of claim 57, wherein the enhancement layer receiving processing means includes: a convolutional deinterleaver for dispersing concatenated error by deinterleaving an enhancement layer stream outputted from the hierarchical receiving means; an external decoder for correcting an error signal by decoding an output signal of the convolutional deinterleaver; a TS demultiplexer for demultiplexing an output singal of the external decoder into multimedia and various supplementary information packets; and a system decoder for depacketizing an output signal of the TS demultiplexer and synchronizing streams.

59. The DMB receiver of claim 56, wherein the hierarchical receiving means includes: a differential demodulator for demodulating the

TC receiving signal based on 4 DQPSK; a frequency deinterleaver for deinterleaving an output signal of the differential demodulator in a frequency domain; and a hierarchical symbol demapper for separating the base layer stream and the enhancement layer stream from an output signal of the frequency deinterleaver and outputting the base layer stream and the enhancement layer stream to the symbol demapper.

60. The DMB receiver of claim 59, wherein the enhancement layer receiving processor includes: a convolutional deinterleaver for dispersing concatenated error by deinterleaving an enhancement layer stream outputted from the hierarchical receiving means; an external decoder for correcting an error signal by decoding an output signal of the convolutional deinterleaver; a TS multiplexer for demultiplexing an output signal of the external decoder into multimedia and various supplementary information packets; and a system decoder for depacketizing an output signal of the TS demultiplexer and synchronizing streams.

61. The DMB receiver of claim 53, wherein the hierarchical receiving means includes: a differential demodulator for demodulating the receiving signal based on ^"-4-^" DQPSK; a frequency deinterleaver for generating a deinterleaved signal by deinterleaving an output signal of the differential demodulator in a frequency domain and outputting the deinterleaved signal to the enhancement layer receiving processing means; a symbol demapper for performing symbol de-mapping onto a base layer stream included in an output signal of the frequency deinterleaver based on QPSK; a time deinterleaver for deinterleaving a base layer stream outputted from the symbol demapper in a time domain; a convolutional decoder for convolution-decoding a base layer stream outputted from the time deinterleaver; and an energy dispersal descrambler for generating a descrambled base layer stream by descrambling a base layer stream outputted from the convolutional decoder to rearrange a signal scrambled for energy dispersion and outputting the descrambled base layer stream to the base layer receiving processing means.

62. The DMB receiver of claim 61, wherein the enhancement layer receiving processing means includes: a hierarchical symbol demapper for separating the enhancement layer stream from an output signal of the frequency deinterleaver; a frequency deinterleaver for deinterleaving an enhancement layer stream outputted from the hierarchical symbol demapper in a frequency domain; a symbol demapper for performing symbol de-mapping onto an enhancement layer stream outputted from the frequency deinterleaver based on QPSK; a time deinterleaver for deinterleaving an enhancement layer stream outputted from the symbol demapper in a time domain; an internal decoder for performing error control decoding onto an enhancement Layer stream outputted from the time deinterleaver; an energy dispersal desciambler for rearranging a signal scrambled for energy dispersion by descrambling an enhancement layer stream outputted from the internal decoder; a convolutional deinterleaver for dispersing concatenated error by deinterleaving an enhancement layer stream outputted from the energy dispersal descrambler; an external decoder for correcting an error signal by decoding an output signal of the convolutional deinterleaver; a TS demultiplexer for demultiplexing an output signal of the external decoder into multimedia and various supplementary information packets; and a system decoder for depacketizing an output signal of the TS demultiplexer and synchronizing streams.

63. The DMB receiver of claim 38, further comprising a scalable multimedia decoder for decoding multimedia data included in the decoded base layer stream and enhancement layer stream.

64. The DMB receiver of claim 38, further comprising: a supplementary data decoder for decoding supplementary data included in the decoded enhancement layer stream; and a multimedia decoder for decoding multimedia data included in the decoded base layer stream.

65. The DMB receiver of claim 38, further comprising: a first multimedia decoder for decoding first multimedia data included in the decoded base layer stream; and a second multimedia decoder for decoding second multimedia data, which is independent from the first multimedia data, as data included in the decoded enhancement layer stream.

66. The DMB receiver of claim 38, wherein the base layer receiving processing means includes: a convolutional deinterleaver for performing convolutional deinterleaving onto a base layer stream outputted from the hierarchical receiving means; a Reed-Solomon decoder for performing additional error control decoding onto an output signal of the convolutional deinterleaver; a TS demultiplexer for demultiplexing an output signal of the RS decoder into multimedia and various supplementary information packets; and a system decoder for depacketizing an output signal of the TS demultiplexer and synchronizing streams.

67. A digital multimedia broadcasting (DMB) receiver, comprising: a hierarchical receiving means for separating an encoded base layer stream and an encoded enhancement layer stream from a receiving signal by performing hierarchical symbol de-mapping onto the receiving signal which is hierarchically symbol mapped by allocating a predeterm bit value by encoding a base layer stream based on DQPSK and allocating a predetermined bit value by encoding an enhancement layer stream based on QPSK; a base layer receiving processing means for decoding the encoded base layer stream; and an enhancement layer receiving processing means for decoding the encoded enhancement layer stream.

68. The DMB receiver of claim 67, wherein the receiving signal is processed by performing hierarchical symbol mapping onto the encoded base layer stream and the encoded enhancement layer stream according to a following table 4 :

Table 4

69. The DMB receiver of claim 67, wherein the hierarchical receiving means includes: a differential demodulator for demodulating the receiving signal based on 4 DQPSK; a frequency deinterleave n for deinterleaving an output signal of the differential demodulator in a frequency domain to thereby generate a deinterleaved signal and outputting the deinterleaved signal to the enhancement layer receiving processing means; a symbol demapper for performing symbol de-mapping onto a base layer stream included in an output signal of the frequency deinterleaver based on QPSK; a time deinterleaver for deinterleaving a base layer stream outputted from the symbol demapper in a time domain; a conventional decoder for performing convolutional decoding onto a base layer stream outputted from the time deinterleaver; and an energy dispersal descrambler for generating a descrambled base layer stream by descrambling a base layer stream outputted from the: convolutional decoder to rearrange a signal scrambled for energy dispersion and outputting the descrambled base layer stream to the base layer receiving processing means.

70. The DMB receiver of claim 69, wherein the enhancement layer receiving processing means includes: a hierarchical symbol demapper for separating the enhancement layer stream from an output signal of the frequency deinterleaver; a time deinterleaver for deinterleaving an enhancement layer stream outputted from the hierarchical symbol demapper in a time domain; a channel decoder for performing error control decoding onto an enhancement layer stream outputted from the time deinterleaver; an energy dispersal descrambler for rearranging a signal scrambled for energy dispersion by descrambling an enhancement layer stream outputted from the channel decoder; a TS demultiplexer for demultiplexing an output signal of the energy dispersal descrambler into multimedia and various supplementary information packets; and a system decoder for depacketizing an output signal of the TS demultiplexer and synchronizing streams.

71. A digital multimedia broadcasting (DMB) receiver, comprising: a hierarchical receiving means for separating an encoded base layer stream and an encoded enhancement layer stream from a receiving signal by performing hierarchical symbol de-mapping onto the receiving signal which is hierarchical symbol mapped for the encoded base layer stream and the encoded enhancement layer stream by allocating a predetermine bit value through encoding a vr base layer stream based on -4 DQPSK and by allocating a predetermined bit value through encoding an enhancement layer stream based on 2-ASK; a base layer receiving processing means for decoding the encoded base layer stream; and an enhancement layer receiving processing means for decoding the enhancement layer stream.

72. The DMB receiver of claim 71, wherein the receiving signal is processed by performing hierarchical symbol mapping onto the encoded base layer stream and the encoded enhancement layer stream using an equation 1:

,£> where ^t. K denotes l ,t^zh to k ,,th QPSK symbols of the encoded base layer stream, and ^zι,κ denotes 1^th to k^th carriers of the encoded enhancement layer stream.

73. The DMB receiver of claim 71, wherein the hierarchical receiving means includes: a differential demodulator for demodulating the receiving signal based on -4 DQPSK; a frequency deinterleaver for deinterleaving an output signal of the differential demodulator in a frequency domain to thereby generate a deinterleaved signal and outputting the deinterleaved signal to the enhancement layer receiving processing means; a symbol demapper for performing symbol de-mapping onto a base layer stream included in an output signal of the frequency deinterleaver based on QPSK; a time deinterleaver for deinterleaving a base layer stream outputted from the symbol demapper in a time domain; a convolutional decoder for performing convolutional decoding onto a base layer stream outputted from the time deinterleaver; and an energy dispersal descrambler for generating a descrambled base layer stream by descrambling a base layer stream outputted from the convolutional decoder to rearrange a signal scrambled for energy dispersion and outputting the descrambled base layer stream to the base layer receiving processing means.

74. The DMB receiver of claim 73, wherein the enhancement layer receiving processing means includes: a hierarchical symbol demapper for separating the enhancement layer stream from an output signal of the frequency deinterleaver; a time deinterleaver for deinterleaving an enhancement layer stream outputted from the hierarchical symbol demapper in a time domain; a channel decoder for performing error control decoding onto an enhancement layer stream outputted from the time deinterleaver; an energy dispersal descrambler for rearranging a signal scrambled for energy dispersion by descrambling an enhancement layer stream outputted from the channel decoder; a TS demultiplexer for demultiplexing an output signal of the energy dispersal descrambler to multimedia and various supplementary information packets; and a system decoder for depacketizing an output signal of the TS demultiplexer and synchronizing streams.