EP1938596A1

EP1938596A1 - Apparatus for transmitting and receiving digital multimedia broadcasting for high-quality video service

Info

Publication number: EP1938596A1
Application number: EP06798928A
Authority: EP
Inventors: Jong-Soo Lim; Hyun Lee; Gwang-Soon Lee; Soo-In Lee; Chieteuk Ahn
Original assignee: Electronics and Telecommunications Research Institute ETRI
Current assignee: Electronics and Telecommunications Research Institute ETRI
Priority date: 2005-09-27
Filing date: 2006-09-27
Publication date: 2008-07-02
Also published as: EP1938596A4; WO2007037618A1

Abstract

Provided is a Digital Multimedia Broadcasting (DMB) transmitting/receiving apparatus. The DMB apparatus for a high-quality video service includes: a source encoder for source-encoding audio and video signals into base layer streams and enhancement layer streams, individually; a base layer transmission processor for receiving the base layer streams from the source encoder, performing system encoding, multiplexing encoded base layer streams into transport streams, and outputting base layer transport streams; an enhancement layer transmission processor for receiving the enhancement layer streams from the source encoder, performing system encoding, multiplexing the encoded enhancement layer streams into enhancement layer transport streams, and outputting enhancement layer transport streams; and a layered digital broadcasting transmitter for receiving the base layer transport streams and the enhancement layer transport streams from the base layer transmission processor and the enhancement layer transmission processor, and modulating the base and enhancement layer transport streams into digital broadcasting signals.

Description

APPARATUS FOR TRANSMITTING AND RECEIVING DIGITAL MULTIMEDIA BROADCASTING FOR HIGH- QUALITY VIDEO SERVICE

Technical Field

[1] The present invention relates to a Digital Multimedia Broadcasting (DMB) transmitting/receiving apparatus for a high-quality video service; and, more particularly, to a DMB transmitting/receiving apparatus that can provide a high-quality video service or an additional service while maintaining inverse compatibility with a conventional DMB system.

[2]

Background Art

[3] Fig. 1 is a block view illustrating a conventional digital multimedia broadcasting

(DMB) transmitting apparatus.

[4] As shown in Fig. 1, the conventional DMB transmitting apparatus includes a

Moving Picture Experts Group 4 (MPEG-4) video encoder 111, an MPEG-4 audio encoder 113, an MPEG-4 system encoder 120, an MPEG-2 transport stream (TS) multiplexer 130, a Reed-Solomon (RS) encoder 140, a convolutional interleaver 150, and a Digital Audio Broadcasting (DAB) transmitter 160. The MPEG-4 video encoder 111 and the MPEG-4 audio encoder 113 encode video and audio sources. The MPEG- 4 system encoder 120 objectizes and synchronizes media streams, and the MPEG-2 TS multiplexer 130 multiplexes the media streams. The RS encoder 140 is used as an external encoder for additional error correction encoding, and the convolutional interleaver 150 is used as an external interleaver to remove temporal correlation between adjacent byte units in data stream. The DAB transmitter 160 receives streams outputted from the convolutional interleaver 150 through a stream mode channel, converts the streams into digital broadcasting signals, and outputs the digital broadcasting signals.

[5] Hereinafter, the DAB transmitter 160 will be described in detail by taking a Eureka-

147 DAB transmitter, which is a European digital audio broadcasting system, as an example.

[6] Fig. 2 is a block view describing a digital audio broadcasting (DAB) transmitter of

Fig. 1. The drawing shows a structure of a Eureka-147 DAB system, which is a European DAB system.

[7] As described in Fig. 1, the DAB transmitter 160 used in the conventional DMB transmitting apparatus includes an energy dispersal scrambler 161, a convolutional encoder 162, a time interleaver 163, a symbol mapper 164, a frequency interleaver 165, a differential modulator 166, an Inverse Fast Fourier Transform (IFFT) 167, and a guard interval inserter 168.

[8] Hereinafter, the operation of the constitutional elements of the DAB transmitter 160 will be described according to operation sequence.

[9] First, MPEG-encoded audio data stream or general data stream inputted to the DAB transmitter 160 are inputted to the energy dispersal scrambler 161 to disperse energy of radio frequency (RF) transmitting signals, and inputted to the convolutional encoder 162 to be convolution-encoded into different encoding rates according to Unequal Error Protection (UEP) or Equal Error Protection (EEP) profile.

[10] Each sub-channel data temporally interleaved in the time interleaver 163 with respect to a section of 16 logic frames is multiplexed in a main service multiplexer (MSM) to thereby form a common interleaved frame (CIF). Herein, since each logic frame includes 24ms information in a time domain, it has an interleaving depth of a total of 384ms.

[11] Subsequently, QPSK symbol mapping is performed by forming a sync channel, a fast information channel (FIC), and a main service channel (MSC) for transmitting valid data to compose a 24ms-long DAB transmitting frame in the symbol mapper 164, and frequency interleaving is performed in the frequency interleaver 165 to minimize the influence regarding frequency selective fading.

[12] The differential demodulator 166 generates a phase reference signal and disposes the phase reference signal in a second symbol of a transmission frame, and performs a differential modulation onto an orthogonal frequency division multiplexing (OFDM) symbol that constitutes a fast information channel (FIC) and a main service channel (MSC) based on the transmission frame.

[13] Subsequently, the OFDM symbols that form the transmission frame go through zero-padding for 2N Inverse Fast Fourier Transform (IFFT) and the zero-padded OFDM symbols of the transmission frame are converted into time domain signals through an IFFT in the IFFT unit 167.

[14] The guard interval inserter 168 inserts data disposed in about a fourth of a valid symbol section in the rear part, which is called a guard interval, into a place before the valid symbols to remove inter-symbol interference (ISI).

[15] In the conventional digital multimedia broadcasting method, the available transmission rate is 1.152Mbps when a convolutional encoding having a 1/2 rate encoding rate is applied. When two video services are applied to one channel, a transmission rate of 576 kbps is assigned to each service.

[16] Therefore, the conventional DMB transmitting apparatus has a limitation in providing a high-quality service, even though a highly efficient source encoding is applied and a transmission rate of 776kbps is provided. [17]

Disclosure of Invention Technical Problem

[18] It is, therefore, an object of the present invention to provide a Digital Multimedia

Broadcasting (DMB) transmitting/receiving apparatus that can provide a high-quality DMB video service and/or additional data service while maintaining compatibility with conventional digital multimedia systems through layered modulation.

[19] It is another object of the present invention to provide a DMB transmitting/ receiving apparatus that can allocate streams to a base layer and an enhancement layer by using a scalable encoding as a source encoding method, and provide a high-quality DMB video service by receiving streams from both base layer and enhancement layer and using a scalable decoding method in a receiver.

[20] Other objects and advantages of the present invention can be understood and become clear by the following description and embodiments of the present invention. Also, it is obvious to those skilled in the art that the objects and advantages of the present invention can be realized by the means as claimed and combinations thereof.

[21]

Technical Solution

[22] In accordance with one aspect of the present invention, there is provided a Digital

Multimedia Broadcasting (DMB) apparatus for a high-quality video service, which includes: a source encoder for performing source encoding onto audio signals and video signals into base layer streams and enhancement layer streams, individually; a base layer transmission processor for receiving the base layer streams from the source encoder, performing system encoding, multiplexing encoded base layer streams into transport streams, and outputting base layer transport streams; an enhancement layer transmission processor for receiving the enhancement layer streams from the source encoder, performing system encoding, multiplexing the encoded enhancement layer streams into enhancement layer transport streams, and outputting enhancement layer transport streams; and a layered digital broadcasting transmitter for receiving the base layer transport streams and the enhancement layer transport streams from the base layer transmission processor and the enhancement layer transmission processor, and modulating the base and enhancement layer transport streams into digital broadcasting signals.

[23] In accordance with another aspect of the present invention, there is provided a

DMB transmitting apparatus for an additional data service, which includes: an additional data source encoder for source-encoding additional data and outputting enhancement layer stream; a base layer source encoder for source-encoding audio signals and video signals and outputting base layer stream; a base layer transmission processor for receiving the base layer stream, performing system encoding, multiplexing encoded base layer stream into transport stream, and outputting base layer transport stream; an enhancement layer transmission processor for receiving the enhancement layer stream, performing system encoding, multiplexing encoded enhancement layer stream into media stream, and outputting enhancement layer transport stream; and a layered digital broadcasting transmitter for receiving the base layer transport streams and the enhancement layer transport streams from the base layer transmission processor and the enhancement layer transmission processor, and modulating the base and enhancement layer transport streams into digital broadcasting signals.

[24] In accordance with another aspect of the present invention, there is provided a

DMB receiving apparatus for a high-quality video service, which includes: a digital broadcasting receiver for receiving digital broadcasting signals, separating the digital broadcasting signals into base layer stream and enhancement layer stream, outputting the enhancement layer stream, and demodulating the base layer stream through symbol de-mapping and outputting the demodulated base layer stream; a base layer reception processor for performing channel decoding onto the demodulated base layer stream to thereby produce transport stream, de-multiplexing the transport stream, performing system decoding, and outputting base layer audio stream and base layer video stream; an enhancement layer reception processor for receiving the enhancement layer stream, demodulating the enhancement layer stream through symbol de-mapping, performing channel decoding to thereby produce transport stream, de-multiplexing the transport stream, performing system decoding, and outputting enhancement layer audio stream and enhancement layer video stream; and a scalable audio/video decoder for performing scalable decoding onto the base layer audio stream, the base layer video stream, the enhancement layer audio stream, and the enhancement layer video stream.

[25] In accordance with another aspect of the present invention, there is provided a

DMB receiving apparatus for an additional data service, which includes: a digital broadcasting receiver for receiving digital broadcasting signals, separating the digital broadcasting signals into base layer stream and enhancement layer stream, outputting the enhancement layer stream, and demodulating the base layer stream through symbol de-mapping and outputting the demodulated base layer stream; a base layer reception processor for performing channel decoding onto the demodulated base layer stream to thereby produce transport stream, de-multiplexing the transport stream, performing system decoding, and outputting base layer audio stream and base layer video stream; an enhancement layer reception processor for receiving the enhancement layer stream, demodulating the enhancement layer stream through symbol de-mapping, performing channel decoding to thereby produce additional data; an audio/video decoder for decoding and outputting the base layer audio stream and the base layer video stream; and an additional data decoder for decoding and outputting the additional data. [26]

Advantageous Effects [27] The present invention provides a high-quality video service and an additional data service while maintaining compatibility with conventional digital multimedia broadcasting networks. [28] Also, the present invention provides a high-quality video service with a higher available transmission rate than conventional DMB systems and simultaneously provides more broadcasting service channels by adding a layered modulation function to a conventional DMB transmitting system. [29]

Brief Description of the Drawings [30] The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which: [31] Fig. 1 is a block view illustrating a conventional digital multimedia broadcasting

(DMB) transmitting apparatus; [32] Fig. 2 is a block view describing a digital audio broadcasting (DAB) transmitter of

Fig. 1; [33] Fig. 3 is a block view showing a DMB transmitting apparatus for a high-quality video service in accordance with an embodiment of the present invention; [34] Fig. 4 is a block view illustrating an enhancement layer transmission processor of

Fig. 3; [35] Fig. 5 is a detailed block view describing the enhancement layer transmission processor of Fig. 3;

[36] Fig. 6 is a block view illustrating a layered DAB transmitter of Fig. 3;

[37] Fig. 7 shows a constellation of a IA Quadrature Phase Shift Keying (QPSK) signal;

[38] Fig. 8 shows a constellation of a signal having one-bit additional information and symbol-mapped in a 2- ASK modulation method in layered symbol mapping in accordance with an embodiment of the present invention; [39] Fig. 9 shows a constellation of a signal having two-bit additional information and symbol-mapped in a QPSK modulation method in layered symbol mapping in accordance with an embodiment of the present invention; [40] Fig. 10 is a block view describing a DMB transmitting apparatus for an additional data service in accordance with an embodiment of the present invention; [41] Fig. 11 is a block view illustrating a DMB receiving apparatus for a high-quality video service in accordance with an embodiment of the present invention;

[42] Fig. 12 is a block view describing a DAB receiver of Fig. 11 ;

[43] Fig. 13 is a flowchart describing a DMB receiving process for a high-quality video service in accordance with an embodiment of the present invention; and

[44] Fig. 14 is a block view showing a DMB receiving apparatus for an additional data service in accordance with an embodiment of the present invention.

[45]

Mode for the Invention

[46] Following description exemplifies only the principles of the present invention. Even if they are not described or illustrated clearly in the present specification, one of ordinary skill in the art can embody the principles of the present invention and invent various apparatuses within the concept and scope of the present invention.

[47] The use of the conditional terms and embodiments presented in the present specification are intended only to make the concept of the present invention understood, and they are not limited to the embodiments and conditions mentioned in the specification.

[48] In addition, all the detailed description on the principles, viewpoints and embodiments and particular embodiments of the present invention should be understood to include structural and functional equivalents to them. The equivalents include not only currently known equivalents but also those to be developed in future, that is, all devices invented to perform the same function, regardless of their structures.

[49] For example, block diagrams of the present invention should be understood to show a conceptual viewpoint of an exemplary circuit that embodies the principles of the present invention. Similarly, all the flowcharts, state conversion diagrams, pseudo codes and the like can be expressed substantially in a computer-readable media, and whether or not a computer or a processor is described distinctively, they should be understood to express various processes operated by a computer or a processor.

[50] Functions of various devices illustrated in the drawings including a functional block expressed as a processor or a similar concept can be provided not only by using hardware dedicated to the functions, but also by using hardware capable of running proper software for the functions. When a function is provided by a processor, the function may be provided by a single dedicated processor, single shared processor, or a plurality of individual processors, part of which can be shared.

[51] The apparent use of a term, processor , control or similar concept, should not be understood to exclusively refer to a piece of hardware capable of running software, but should be understood to include a digital signal processor (DSP), hardware, and ROM, RAM and non- volatile memory for storing software, implicatively. Other known and commonly used hardware may be included therein, too.

[52] Other objects 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. The same reference numeral is given to the same element, although the element appears in different drawings. In addition, if further detailed description on the related prior arts is determined to obscure the point of the present invention, the description will not be provided. Hereafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[53] Fig. 3 is a block view showing a DMB transmitting apparatus for a high-quality video service in accordance with an embodiment of the present invention.

[54] As described in Fig. 3, the DMB transmitting apparatus includes a Moving Picture

Experts Group 4 (MPEG-4) scalable video encoder 211, an MPEG-4 scalable audio encoder 213, an enhancement layer transmission processor 220, a base layer transmission processor 230, and a layered Digital Audio Broadcasting (DAB) transmitter 240.

[55] The MPEG-4 scalable video encoder 211 generates base layer video stream, which is compatible with conventional DMB systems, and enhancement layer video stream for an improved quality out of a video source, and outputs the base layer video stream and the enhancement layer video stream to the base layer transmission processor 230 and the enhancement layer transmission processor 220, respectively.

[56] The MPEG-4 scalable audio encoder 213 generates base layer audio stream, which is compatible with conventional DMB systems, and enhancement layer audio stream for an improved quality out of an audio source, and outputs the base layer audio stream and the enhancement layer audio stream to the base layer transmission processor 230 and the enhancement layer transmission processor 220, respectively.

[57] Herein, the enhancement layer video stream and the enhancement layer audio stream can be generated by using diverse scalable techniques such as time scalability, space scalability, and signal-to-noise ratio (SNR) scalability. Since the scalable techniques are widely known to those skilled in the art to which the present invention pertains, detailed description on them will not be provided herein. A conventional DMB standard document ETSI EN 300 401 may be referred to as a background art of the present invention in connection with the embodiments of the present invention. Hereinafter, while the present invention is described, what is described in the standard document will not be described in the present specification in detail and newly suggested part in addition to the technology of the standard document will be described in detail.

[58] Referring to Fig. 4, the base layer transmission processor 230 includes an MPEG-4 system encoder 120, an MPEG-2 transport stream (TS) multiplexer (MUX) 130, a Reed-Solomon (RS) encoder 140, and a convolutional interleaver 150. The functions of the constituent elements are as described with reference to Fig. 1.

[59] The base layer transmission processor 230 processes base layer video stream and base layer audio stream supported by conventional DMB systems. The MPEG-4 system encoder 120 objectizes the base layer video stream and the base layer audio stream, which are transmitted from the MPEG-4 scalable video encoder 211 and the MPEG-4 audio scalable encoder 213, respectively, and synchronizes the base layer video and audio streams with each other. Then, the MPEG-2 TS multiplexer 130 multiplexes the base layer video and audio streams into base layer transport stream, and the RS encoder 140 performs error correction coding onto the base layer transport stream. Subsequently, the convolutional interleaver 150 removes time correlation among adjacent byte units within stream and outputs the result to the layered DAB transmitter 240.

[60] The enhancement layer transmitter 220 is a structure for processing the enhancement layer video stream and the enhancement layer audio stream to provide video in a higher quality than the video of the base layer. The enhancement layer transmission processor 220 will be described with reference to Fig. 5 later.

[61] The layered DAB transmitter 240 includes a layered symbol mapper for processing both base layer stream and enhancement layer stream in addition to the structure of the above-described conventional DAB transmitter. The layered DAB transmitter 240 will be described in detail with reference to Fig. 6.

[62] Fig. 5 is a detailed block view describing the enhancement layer transmission processor 220 of Fig. 3. As shown in the drawing, the enhancement layer transmission processor 220 includes an MPEG-4 system encoder 221, an MPEG-2 TS multiplexer 222, an energy dispersal scrambler 223, a channel encoder 224, and a time interleaver 225.

[63] The MPEG-4 system encoder 221 objectizes the enhancement layer video stream and the enhancement layer audio stream, synchronizes the streams, and outputs the synchronized streams to the MPEG-2 TS multiplexer 222.

[64] The MPEG-2 TS multiplexer 222 multiplexes the enhancement layer video stream and the enhancement layer audio stream, which are transmitted from the MPEG-4 system encoder 221 into enhancement layer transport stream and outputs the enhancement layer transport stream.

[65] The energy dispersal scrambler 223 receives the enhancement layer transport stream and performs energy dispersal of a transmitting signal onto the received enhancement layer transport stream. Herein, the energy dispersal may be performed based on a dispersal polynomial expression of the aforementioned standard document ETSI EN 300401. [66] The channel encoder 224 receives the energy dispersed enhancement layer transport stream and encodes a wireless communication channel to have a robust error correction function. Examples of the error correcting channel coding include RS coding, con- volutional coding, Low Density Parity Check (LDPC) coding, turbo coding, and concatenated coding method thereof. The error correcting channel coding is performed by using a Rate Compatible Punctured Code (RCPC) that can provide variable channel coding rates or a structure capable of changing the coding rate of a channel code.

[67] The time interleaver 225 is a structure for dispersing error caused by fading in a wireless transmission channel. In the present embodiment, the time interleaver 225 performs time interleaving by using a time interleaving method defined in the aforementioned standard document, and outputs bit streams. The bit streams outputted from the time interleaver 225 are inputted to the layered symbol mapper 241 of the layered DAB transmitter 240, which will be described later.

[68] Fig. 6 is a block view illustrating the layered DAB transmitter 240 of Fig. 3. As shown in the drawing, the layered DAB transmitter 240 includes the layered symbol mapper 241 in addition to the structure of the conventional DAB transmitter, which is described above with reference to Fig. 2.

[69] To be specific, the layered DAB transmitter 240 includes the layered symbol mapper 241 between the differential modulator 166 and the Inverse Fast Fourier Transform (IFFT) unit 167 in addition to the constituent elements of the conventional DAB transmitter, which includes the energy dispersal scrambler 161, the convolutional encoder 162, the time interleaver 163, the symbol mapper 164, the frequency interleaver 165, the differential modulator 166, the IFFT 167, and the guard interval inserter 168. Hereinafter, the layered symbol mapper, which is newly suggested in the present invention, will be described among the constituent elements of the layered DAB transmitter 240. The conventional constituent elements will not be described herein.

[70] The layered symbol mapper 241 performs symbol mapping onto encoded enhancement layer transport stream transmitted from the enhancement layer transmission processor 220 based on a modulation signal of a base layer transport stream outputted from the differential modulator 166, and outputs the symbol mapping result to the IFFT 167.

[71] The layered symbol mapping process of the present invention is as follows. Two bits are allocated to a base layer transport stream in the symbol mapper 164 by performing Quaternary Phase Shift Keying (QPSK), and a position on a quadrant line is determined based on the two bits in the differential modulator 166. Herein, the quadrants means real-number and imaginary number axes rotated by π/4.

[72] Enhancement layer transport stream goes through any one among 2- Amplitude Shift Keying (2- ASK), Quaternary Phase Shift Keying (QPSK), 16-Quadrature Amplitude Modulation (QAM), and other similar modulation methods. Except the two bits for the base layer, the 2- ASK method can allocate one bit, and the QPSK can allocate two bits to secure additional transmission rates. The 16-QAM can allocate 4 bits to secure additional transmission rates. Symbols of the enhancement layer are mapped by applying constellation based on a modulation method of the enhancement layer to the positions on the quadrants determined in the base layer.

[73]

[74] The layered symbol mapping method of the present invention will be described hereinafter with reference to embodiments.

[75] When a k QPSK symbol of an 1 OFDM symbol obtained by performing frequency interleaving onto base layer transport stream is defined as y , the output z^b of the differential modulator 166 of the base layer transport stream can be defined as Equation 1.

[76]

[77]

Z !,k = Z i-i,k - y_{l k} ( 1=2 , 3 , 4 , . . . , L , - KI l ≤ k ≤ K I l )

[78] Eq. 1

[79]

[80] where L denotes the number of OFDM symbols; K denotes the number of multi- carriers; and z^h,,_k is generated in a phase reference symbol generator (not shown).

[81]

[82] The Equation 1 signifies that each carrier is modulated in a π/4 QPSK modulation method. Therefore,

z is any one between

and ι>Λ A _*>-. ,A)

. Herein, the size of a modulated symbol is assumed to be 1. Fig. 7 shows a constellation of a IA QPSK signal. [83] When a k ^th carrier of an

I ^th

OFDM of an enhancement layer transport stream is defined as z^eι,_k

, the output

^Z l ,k of the layered symbol mapper 241 can be defined as Equation 2.

[84] [85]

Z l , k = ζ ( ^z l , k r ^z l , k )

Eq. 2 [86] [87] where denotes a layered symbol mapping function and it is determined based on modulation method and the number of additional information bits of the enhancement layer. [88] According to an embodiment of the layered symbol mapper 241, when the additional information of the enhancement layer is 1 bit and a 2-ASK modulation is used, the layered symbol mapper 241 can be designed as the following Equation 3.

[89]

[90]

- 7i,, Λ «.- - Δ— Ji-Ti-¹L V" A, A ' — i

Eq. 3

[91]

[92] where a is a constant number larger than 0.

[93]

[94] Fig. 8 shows a constellation of a signal having one-bit additional information and symbol-mapped in a 2-ASK modulation method in layered symbol mapping in accordance with an embodiment of the present invention. The constellation shown as black dots in Fig. 4 is a constellation for symbol-mapped signals of the base layer, whereas the constellation shown as white dots is a constellation for symbol-mapped signals of the enhancement layer.

[95] In accordance with another embodiment of the layered symbol mapping, a layered symbol mapping function is as shown in Table 1 below, when the additional information of the enhancement layer is two bits and QPSK modulation is used. A constellation of symbol mapped signals based on the Table 1 is presented in Fig. 9.

[96] [97] Table 1 [98]

[99] [100] where A denotes information bit corresponding to z^eι,_k

; B denotes information bit corresponding to

; and a is a constant number larger than 0.

[101] [102] When the additional information of the enhancement layer is more than three bits, layered symbol mapping constellations can be extended in a similar method based on the base layer information and the enhancement layer information.

[103] Basically, the enhancement layer is supposed to be applied to only a channel through which data are actually transmitted, i.e., MSC, in the structure of a DMB frame. However, if necessary, it is possible to apply the enhancement layer to both MSC and FlC, a channel which provide system information. Also, information on layered modulation, such as whether layer modulation is used, a modulation method used when layer information is used, encoding rate of a channel encoder, and service information related to an enhancement layer, may be transmitted through the FlC so that a DMB receiving apparatus receives information on the enhancement layer.

[104] Fig. 10 is a block view describing a DMB transmitting apparatus for an additional data service in accordance with an embodiment of the present invention.

[105] An enhancement layer may be used as an additional transmission channel for providing an additional service, other than the aforementioned purpose of providing a high-quality service. In other words, an additional video service may be provided by using an additional source encoder for the enhancement layer. The additional video service may be related to the base layer, such as stereoscopic video and multi- viewpoint video, or it may be independent and different service.

[106] As shown in Fig. 10, the DMB transmitting apparatus for providing an additional data service, which is suggested in the present invention, includes an additional data source encoder 115, an enhancement layer transmission processor 220, an MPEG-4 video encoder 111, an MPEG-4 audio encoder 113, a base layer transmission processor 230, and a layered DAB transmitter 240.

[107] The additional data source encoder 115 encodes data for an additional service and outputs the encoded additional data. The enhancement layer transmission processor 220 processes the additional data outputted from the additional data source encoder 115 into above-described enhancement layer signals. The MPEG-4 video and audio encoders 111 and 113 encode video and audio signals of the base layer and outputs base layer video and audio signals, respectively. The base layer transmission processor 230 receives and processes the base layer signals outputted from the MPEG-4 video encoder 111 and the MPEG-4 audio encoder 113. The MPEG-4 video encoder 111, the MPEG-4 audio encoder 113, the enhancement layer transmission processor 220, the base layer transmission processor 230, and the layered DAB transmitter 240 function as described above.

[108] According to the present embodiment where data packets for diverse additional data services are transmitted through the enhancement layer, it is possible to provide an additional data service in connection with diverse services provided in a conventional DMB system or independently from the conventional services.

[109] Fig. 11 is a block view illustrating a DMB receiving apparatus for a high-quality video service in accordance with an embodiment of the present invention, and Fig. 12 is a block view describing a DAB receiver of Fig. 11. [110] As shown in Fig. 11, the DMB receiving apparatus for a high-quality video service includes a DAB receiver 310, a base layer reception processor 320, an enhancement layer reception processor 330, an MPEG-4 scalable video decoder 340, and an MPEG- 4 scalable audio decoder 350.

[Ill] The base layer reception processor 320 is the same constituent element as a conventional DMB receiver and it includes a convolutional decoder 321, an RS decoder 322, a TS de-multiplexer 323, and an MPEG-4 system decoder 324. The enhancement layer reception processor 330 includes a layered symbol de-mapper 331, a time de- interleaver 332, a channel decoder 333, an energy dispersal de-scrambler 334, a TS demultiplexer 335, and an MPEG-4 system decoder 336. The enhancement layer reception processor 330 decodes base layer signals and enhancement layer signals through a process in reverse to the encoding process in the above-described DMB transmitting apparatus for a high-quality video service.

[112] Referring to Fig. 12, the DAB receiver 310 is a Eureka 147 DAB receiving apparatus including an RF tuner 311, an AD converter 312, an FFT 313, a differential demodulator 314, a frequency de-interleaver 315, a symbol de-mapper 316, a time de- interleaver 317, a convolutional decoder 318, and an energy dispersal de-scrambler 319.

[113] The DAB receiver 310 receives broadcasting signals and extracts information for diverse services and data streams through a process in reverse to a process in the above-described DAB transmitter.

[114] Particularly, the frequency de-interleaver 315 of the DAB receiver 310 separates base layer stream and enhancement layer stream. The base layer stream is channel- decoded in the same process as a conventional DMB receiver, and the enhancement layer stream is outputted to the enhancement layer reception processor 330 and channel-decoded through the layered symbol de-mapper 331, the time de-interleaver 332, the channel decoder 333, and the energy dispersal de-scrambler 334.

[115] The channel-decoded streams of the two layers are separated into video, audio, and diverse additional information packets in the TS de-multiplexers 323 and 335 and extracted as video and audio streams of the two layers through de-packetization and synchronization between the streams in the MPEG-4 system decoders 324 and 336.

[116] The MPEG-4 scalable video decoder 340 and the MPEG-4 scalable audio decoder

350 perform scalable decoding onto the video streams and audio stream of the base layer and the enhancement layer based on correlation between the two layers to thereby provide high-quality video and audio to a user.

[117] Meanwhile, when the DMB receiving apparatus of the present invention receives broadcasting signals transmitted from a conventional DMB system, it extracts only the base layer stream and provides basic-quality video and audio through the same decoding process of the conventional DMB receiving system.

[118] Fig. 13 is a flowchart describing a DMB receiving process for a high-quality video service in accordance with an embodiment of the present invention.

[119] At step Sl 10, a Eureka-147 DAB receiving apparatus receives broadcasting signals.

At step S 120, diverse multiplexing and service information transmitted through an FIC of a transmission frame are analyzed. At step S 130, information related to a broadcasting channel, multiplexing, and other information related to the service are extracted to acquire broadcasting channel information.

[120] When the broadcasting channel information indicates that the broadcasting is a high-quality broadcasting composed of base layer information and enhancement layer information, at step S 151, the broadcasting signals are separated into streams for the two layers and go through individual channel decoding processes. At step S 152, media decoding is performed based on MPEG-2 and MPEG-4, and at step S 153, a high- quality service is provided.

[121] Meanwhile, when the acquired broadcasting information indicates a conventional broadcasting, only base layer streams are extracted, and channel decoding and media decoding are performed at steps S 141 and S 142, respectively, just as in the conventional DMB receiving apparatus. Then, at step S153, basic-quality service is provided.

[122] Fig. 14 is a block view showing a DMB receiving apparatus for an additional data service in accordance with an embodiment of the present invention.

[123] As described in Fig. 14, the DMB receiving apparatus includes a DAB receiver 310, a base layer receiving processor 320, an enhancement layer receiving processor 330, an MPEG-4 video decoder 410, an MPEG-4 audio decoder 420, and an additional data decoder 430.

[124] Since the DAB receiver 310, the base layer receiving processor 320, and the enhancement layer receiving processor 330 are the same as described above with reference to Figs. 11 and 12. If any, the enhancement layer receiving processor 330 receives enhancement layer stream and finally outputs additional data, and the TS demultiplexer 335 and the MPEG-4 system decoder 336 may not be provided according to the kind of the additional data.

[125] Since the MPEG-4 video decoder 410 and the MPEG-4 audio decoder 420 receives base layer video stream and base layer audio stream, which are outputted from the base layer reception processor, performs decoding onto the base layer video and audio streams, and outputs decoded base layer streams.

[126] The additional data decoder 330 receives the additional data from the enhancement layer reception processor 330, performs decoding according to the kind of the additional data, and outputs decoded additional data. [127] The present application contains subject matter related to Korean patent application

Nos. 2005-0090067 and 2006-0065109, filed with the Korean Intellectual Property Office on September 27, 2005, and July 11, 2006, the entire contents of which is incorporated herein by reference.

[128] 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.

[129]

Claims

[1] A Digital Multimedia Broadcasting (DMB) apparatus for a high-quality video service, comprising: a source encoding means for performing source encoding onto audio signals and video signals and outputting base layer streams and enhancement layer streams, individually; a base layer transmission processing means for receiving the base layer streams from the source encoding means, performing system encoding, multiplexing encoded base layer streams, and outputting base layer transport streams; an enhancement layer transmission processing means for receiving the enhancement layer streams from the source encoding means, performing system encoding, multiplexing the encoded enhancement layer streams, and outputting enhancement layer transport streams; and a layered digital broadcasting transmitting means for receiving the base layer transport streams and the enhancement layer transport streams from the base layer transmission processing means and the enhancement layer transmission processing means, and modulating the base and enhancement layer transport streams into digital broadcasting signals.

[2] The apparatus as recited in claim 1, wherein the layered digital broadcasting transmitting means modulates the base layer transport streams to thereby produce a base layer stream modulation signal, and then modulates the enhancement layer transport streams by performing symbol mapping based on the base layer stream modulation signal.

[3] The apparatus as recited in claim 1, wherein the source encoding means includes: a scalable video encoder for generating base layer video stream, which is compatible with a conventional DMB system, and enhancement layer video stream for a high-quality video service from a video source by using a scalability technique; and a scalable audio encoder for generating base layer audio stream, which is compatible with a conventional DMB system, and enhancement layer audio stream for a high-quality audio service from a audio source by using a scalability technique.

[4] The apparatus as recited in claim 1, wherein the base layer transmission processing means includes: a system encoder for objectizing and synchronizing the base layer stream; a transport stream multiplexer for multiplexing output streams of the system encoder into MPEG-2 transport stream (TS) and outputs base layer transport stream; an external encoder for performing additional error correction encoding onto the base layer transport stream outputted from the transport stream multiplexer; and an external interleaver for removing time correlation between adjacent byte units within stream outputted from the external encoder.

[5] The apparatus as recited in claim 4, wherein the external encoder is a Reed-

Solomon (RS) encoder.

[6] The apparatus as recited in claim 4, wherein the external interleaver is a con- volutional interleaver.

[7] The apparatus as recited in claim 1, wherein the enhancement layer transmission processing means includes: a system encoder for objectizing and synchronizing the enhancement layer stream; a transport stream multiplexer for multiplexing the streams outputted from the system encoder into enhancement layer transport stream; an energy dispersal scrambler for performing energy dispersal onto the enhancement layer transport stream; a channel encoder for performing channel encoding onto the energy-dispersed enhancement layer transport stream to have a robust error correction function with respect to a wireless transmission channel; and a time interleaver for performing time interleaving to disperse an error caused by fading of the wireless transmission channel and outputting enhancement layer bit stream.

[8] The apparatus as recited in claim 7, wherein the enhancement layer transport stream is MPEG-2 transport stream.

[9] The apparatus as recited in claim 7, wherein the channel encoder performs the channel encoding by using any one selected from the group consisting of an RS code, a convolutional code, a low-density parity check (LDPC) code, a turbo code, and concatenated codes thereof.

[10] The apparatus as recited in claim 1, wherein the layered digital broadcasting transmitting means includes: a symbol mapper for performing symbol mapping onto the base layer transport stream to thereby produce a symbol-mapped signal; a frequency interleaver for performing frequency interleaving onto the symbol- mapped signal to thereby produce a frequency-interleaved signal; a differential modulator for differentially modulating the frequency-interleaved signal; and a layered symbol mapper for performing symbol mapping onto the enhancement layer transport stream based on the base layer modulation signal transmitted from the differential modulator.

[11] The apparatus as recited in claim 10, wherein the symbol mapper performs

Quadrature Phase Shift Keying (QPSK) symbol mapping onto the base layer transport stream, and the differential modulator generates a phase reference signal and differentially modulates an Orthogonal Frequency Division Multiplexing (OFDM) symbol constituting an fast information channel (FIC) and an main service channel (MSC).

[12] The apparatus as recited in claim 10, wherein the layered symbol mapper performs 2- ASK modulation onto enhancement layer transport stream based on the symbol-mapped modulation signal of the base layer transport stream.

[13] The apparatus as recited in claim 12, wherein the layered symbol mapper performs symbol mapping onto the enhancement layer transport stream based on an equation expressed as:

^•7,

' Ji- Λ-SΛ. V~ J^ Λ ?

where a is a constant number larger than 0; z^b is a modulation signal of base l,k layer transport stream; z^eι,_k is a symbol for a k* carrier of an 1^th OFDM symbol of enhancement layer transport stream; 1=2,3,4,..., L; -K/2≤k≤K/2; L denotes the number of OFDM symbols; and K denotes the number of multi-carriers.

[14] The apparatus as recited in claim 10, wherein the layered symbol mapper performs QPSK modulation onto the enhancement layer transport stream based on the symbol-mapped modulation signal of the base layer transport stream.

[15] The apparatus as recited in claim 10, wherein the layered symbol mapper performs 16-QAM modulation onto the enhancement layer transport stream based on the symbol-mapped modulation signal of the base layer transport stream.

[16] A Digital Multimedia Broadcasting (DMB) transmitting apparatus for an additional data service, comprising: an additional data source encoding means for source-encoding additional data and outputting enhancement layer stream; a base layer source encoding means for source-encoding audio signals and video signals and outputting base layer stream; a base layer transmission processing means for receiving the base layer stream, performing system encoding, multiplexing encoded base layer stream into transport stream, and outputting base layer transport stream; an enhancement layer transmission processing means for receiving the enhancement layer stream, performing system encoding, multiplexing encoded enhancement layer stream into media stream, and outputting enhancement layer transport stream; and a layered digital broadcasting transmitting means for receiving the base layer transport streams and the enhancement layer transport streams from the base layer transmission processing means and the enhancement layer transmission processing means, and modulating the base and enhancement layer transport streams into digital broadcasting signals.

[17] The apparatus as recited in claim 16, wherein the layered digital broadcasting transmitting means modulates the base layer transport streams to thereby produce a base layer stream modulation signal, and then modulates the enhancement layer transport streams by performing symbol mapping based on the base layer stream modulation signal.

[18] The apparatus as recited in claim 16, wherein the base layer transmission processing means includes: a system encoder for objectizing and synchronizing the base layer stream; a transport stream multiplexer for multiplexing output streams of the system encoder into MPEG-2 transport stream (TS) and outputs base layer transport stream; an external encoder for performing additional error correction coding onto the base layer transport stream outputted from the transport stream multiplexer; and an external interleaver for removing time correlation between adjacent byte units within stream outputted from the external encoder.

[19] The apparatus as recited in claim 16, wherein the enhancement layer transmission processing means includes: a system encoder for objectizing and synchronizing the enhancement layer stream; a transport stream multiplexer for multiplexing the streams outputted from the system encoder into enhancement layer transport stream; an energy dispersal scrambler for performing energy dispersal onto the enhancement layer transport stream; a channel encoder for performing channel encoding onto the energy-dispersed enhancement layer transport stream to have a robust error correction function with respect to a wireless transmission channel; and a time interleaver for performing time interleaving to disperse an error caused by fading of the wireless transmission channel and outputting enhancement layer bit stream.

[20] The apparatus as recited in claim 16, wherein the layered digital broadcasting transmitting means includes: a symbol mapper for performing symbol mapping onto the base layer transport stream to thereby produce a symbol-mapped signal; a frequency interleaver for performing frequency interleaving onto the symbol- mapped signal to thereby produce a frequency-interleaved signal; a differential modulator for differentially modulating the frequency-interleaved signal; and a layered symbol mapper for performing symbol mapping onto the enhancement layer transport stream based on the base layer modulation signal transmitted from the differential modulator.

[21] The apparatus as recited in claim 20, wherein the symbol mapper performs

[22] The apparatus as recited in claim 20, wherein the layered symbol mapper performs 2- ASK modulation onto enhancement layer transport stream based on the symbol-mapped modulation signal of the base layer transport stream.

[23] The apparatus as recited in claim 22, wherein the layered symbol mapper performs symbol mapping onto the enhancement layer transport stream based on an equation expressed as:

— ¹^ f_Ψ* J¹ \ ¹ ^' Ik

where a is a constant number larger than 0; z^b is a modulation signal of base l,k layer transport stream; z^et,k is a symbol for a k ^th carrier of an OFDM symbol of enhancement layer transport stream; 1=2,3,4,..., L; -KIl≤k≤KI 2; L denotes the number of OFDM symbols; and K denotes the number of multi- carriers.

[24] The apparatus as recited in claim 20, wherein the layered symbol mapper performs QPSK modulation onto the enhancement layer transport stream based on the symbol-mapped modulation signal of the base layer transport stream.

[25] The apparatus as recited in claim 20, wherein the layered symbol mapper performs 16-QAM modulation onto the enhancement layer transport stream based on the symbol-mapped modulation signal of the base layer transport stream.

[26] A Digital Multimedia Broadcasting (DMB) receiving apparatus for a high- quality video service, comprising: a digital broadcasting receiver for receiving digital broadcasting signals, separating the digital broadcasting signals into base layer stream and enhancement layer stream, outputting the enhancement layer stream, and demodulating the base layer stream through symbol de-mapping and outputting the demodulated base layer stream; a base layer reception processor for performing channel decoding onto the demodulated base layer stream to thereby produce transport stream, demultiplexing the transport stream, performing system decoding, and outputting base layer audio stream and base layer video stream; an enhancement layer reception processor for receiving the enhancement layer stream, demodulating the enhancement layer stream through symbol de- mapping, performing channel decoding to thereby produce transport stream, demultiplexing the transport stream, performing system decoding, and outputting enhancement layer audio stream and enhancement layer video stream; and a scalable audio/video decoder for performing scalable decoding onto the base layer audio stream, the base layer video stream, the enhancement layer audio stream, and the enhancement layer video stream.

[27] The DMB receiving apparatus as recited in claim 26, wherein the digital broadcasting receiver uses a Eureka 147 Digital Audio Broadcasting (DAB) receiver.

[28] The DMB receiving apparatus as recited in claim 27, wherein the base layer stream and the enhancement layer stream are separated from a frequency de- interleaver of the Eureka 147 DAB receiver.

[29] The DMB receiving apparatus as recited in claim 26, wherein the enhancement layer reception processor includes: a layered symbol de-mapper for performing symbol de-mapping onto the enhancement layer stream; a channel decoder for performing channel decoding onto the symbol de-mapped enhancement layer stream; a de-multiplexer for separating the channel-decoded enhancement layer stream into video packets and audio packets and performing de-multiplexing; and a system decoder for de-packetizing the de-multiplexed audio and video packets, performing synchronization between streams, and outputting enhancement layer audio stream and enhancement layer video stream.

[30] A Digital Multiplexing Broadcasting (DMB) receiving apparatus for an additional data service, comprising: a digital broadcasting receiver for receiving digital broadcasting signals, separating the digital broadcasting signals into base layer stream and enhancement layer stream, outputting the enhancement layer stream, and demodulating the base layer stream through symbol de-mapping and outputting the demodulated base layer stream; a base layer reception processor for performing channel decoding onto the demodulated base layer stream to thereby produce transport stream, demultiplexing the transport stream, performing system decoding, and outputting base layer audio stream and base layer video stream; an enhancement layer reception processor for receiving the enhancement layer stream, demodulating the enhancement layer stream through symbol de- mapping, performing channel decoding to thereby produce additional data; an audio/video decoder for decoding and outputting the base layer audio stream and the base layer video stream; and an additional data decoder for decoding and outputting the additional data.

[31] The DMB receiving apparatus as recited in claim 30, wherein the digital broadcasting receiver uses a Eureka 147 Digital Audio Broadcasting (DAB) receiver.